#!/bin/sh
":" //# -*- mode: js -*-; exec /usr/bin/env TMPDIR=/tmp node --max-old-space-size=2000 --stack-size=42000 "$0" "$@"

"use strict";

/*

MIT License

Copyright (c) 2016 Vadim Shlyakhov

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

*/

const packageInfo = require('./package.json');
const os = require( 'os' )
const osPath = require( 'path' )
const osProcess = require( 'process' )
const url = require( 'url' )
const crypto = require( "crypto" )

const command = require('commander')
const fs = require( 'fs-extra' )
const expandHomeDir = require( 'expand-home-dir' )
const lzma = require( 'lzma-native' )
const cheerio = require('cheerio')

const uuidv4 = require( "uuid/v4" )
const csvParse = require( 'csv-parse' )
const csvParseSync = require( 'csv-parse/lib/sync' )
const zlib = require( 'mz/zlib' )
const sqlite = require( 'sqlite' )
const sharp = require( 'sharp' )

const genericPool = require( 'generic-pool' )
const mozjpeg = require( 'mozjpeg' )
const childProcess = require('child_process')
const isAnimated = require('animated-gif-detector')

const mimeDb = require( 'mime-db' )
const mimeTypes = require( 'mime-types' )
const mmmagic = require( 'mmmagic' )
const mimeMagic = new mmmagic.Magic( mmmagic.MAGIC_MIME_TYPE )

const moment = require("moment")
require("moment-duration-format")

const cpuCount = os.cpus().length

const startTime = Date.now()

function elapsedStr( from , to = Date.now()) {
    return moment.duration( to - from ).format('d[d]hh:mm:ss.SSS',{ stopTrim: "h" })
}

function print ( ...args ) {
    console.log( ... args )
}

const tick = (( slow ) => {
    let ping = 0
    return () => {
        if (( ping++ ) % slow == 0 )
            osProcess.stdout.write( '.' )
    }
}) ( 100 )

function log ( ...args ) {
    if ( command.quiet )
        return
    else if ( command.verbose )
        console.log( elapsedStr( startTime ), ... args )
    else
        tick()
}

function warning ( ...args ) {
    log( elapsedStr( startTime ), ...args )
}

function fatal ( ...args ) {
    console.trace( elapsedStr( startTime ), ... args )
    osProcess.exit( 1 )
}

var srcPath
var outPath
var out // output file writer

var wikiDb
var dirQueue
var clusterWriter

var mainPage = {}

// -    layout, eg. the LayoutPage, CSS, favicon.png (48x48), JavaScript and images not related to the articles
// A    articles - see Article Format
// B    article meta data - see Article Format
// I    images, files - see Image Handling
// J    images, text - see Image Handling
// M    ZIM metadata - see Metadata
// U    categories, text - see Category Handling
// V    categories, article list - see Category Handling
// W    categories per article, category list - see Category Handling
// X    fulltext index - see ZIM Index Format

var headerLength = 80
var header = {
    magicNumber: 72173914,  //    integer      0  4   Magic number to recognise the file format, must be 72173914
    // version                    integer      4  4   ZIM=5, bytes 1-2: major, bytes 3-4: minor version of the ZIM file format
    versionMajor: 5,
    versionMinor: 0,
    uuid: uuidv4( {}, Buffer.alloc( 16 )), // integer 8 16   unique id of this zim file
    articleCount: 0,     //    integer     24  4   total number of articles
    clusterCount: 0,     //    integer     28  4   total number of clusters
    urlPtrPos: null,        //    integer     32  8   position of the directory pointerlist ordered by URL
    titlePtrPos: null,      //    integer     40  8   position of the directory pointerlist ordered by Title
    clusterPtrPos: null,    //    integer     48  8   position of the cluster pointer list
    mimeListPos: headerLength, // integer     56  8   position of the MIME type list (also header size)
    mainPage: 0xffffffff,   //    integer     64  4   main page or 0xffffffff if no main page
    layoutPage: 0xffffffff, //    integer     68  4   layout page or 0xffffffffff if no layout page
    checksumPos: null,      //    integer     72  8   pointer to the md5checksum of this file without the checksum itself. This points always 16 bytes before the end of the file.
    //~ geoIndexPos: null,  //    integer     80  8   pointer to the geo index (optional). Present if mimeListPos is at least 80.
}

function fullPath ( path ) {
    return osPath.join( srcPath, path )
}

function mimeFromPath ( path ) {
    var mType = mimeTypes.lookup( path )
    if ( mType == null ) {
        console.error( 'No mime type found', path )
    }
    return mType
}

function mimeFromData ( data ) {
    return new Promise(( resolve, reject ) =>
        mimeMagic.detect( data, ( error, mimeType ) => {
            if ( error )
                return reject( error )
            return resolve( mimeType )
        })
    )
}

var REDIRECT_MIME = '@REDIRECT@'
var LINKTARGET_MIME = '@LINKTARGET@'
var DELETEDENTRY_MIME = '@DELETEDENTRY@'

var mimeTypeList = []

var maxMimeLength = 512

function mimeFromIndex ( idx ) {
    return mimeTypeList[ idx ]
}

function mimeTypeIndex ( mimeType ) {
    if ( mimeType == null ) {
        console.trace( 'No mime type found', mimeType )
        osProcess.exit( 1 )
    }
    if ( mimeType == REDIRECT_MIME )
        return 0xffff
    if ( mimeType == LINKTARGET_MIME )
        return 0xfffe
    if ( mimeType == DELETEDENTRY_MIME )
        return 0xfffd
    let idx = mimeTypeList.indexOf( mimeType )
    if ( idx == -1 ) {
        idx = mimeTypeList.length
        mimeTypeList.push( mimeType )
    }
    return idx
}

function getNameSpace ( mimeType ) {
    if ( command.uniqueNamespace )
        return 'A'
    if ( !mimeType )
        return null
    if ( mimeType == 'text/html' )
        return 'A'
    else if ( mimeType.split( '/' )[ 0 ] == 'image' )
        return 'I'
    return '-'
}

function mimeFromData ( data ) {
    return new Promise(( resolve, reject ) =>
        mimeMagic.detect( data, ( error, mimeType ) => {
            if ( error )
                return reject( error )
            return resolve( mimeType )
        })
    )
}

function writeUIntLE( buf, value, offset, byteLength ) {
    if ( byteLength == 8 ) {
        value = BigInt( value )
        var low = value & 0xffffffffn
        var high = ( value - low ) / 0x100000000n
        buf.writeUInt32LE( Number( low ), offset )
        buf.writeUInt32LE( Number( high ), offset + 4 )
        return offset + byteLength
    } else {
        return buf.writeUIntLE( Number( value ), offset, byteLength )
    }
}

function toBuffer( value, byteLength ) {
    const buf = Buffer.allocUnsafe( byteLength )
    writeUIntLE( buf, value, 0, byteLength )
    return buf
}

function chunksToBuffer( list ) {
    const chunks = []
    for ( const item of list ) {
        let buf
        if ( Array.isArray( item )) {
             buf = toBuffer( ...item )
        } else {
            buf = Buffer.from( item )
        }
        chunks.push( buf )
    }
    return Buffer.concat( chunks )
}

async function spawn ( command, args, input ) { // after https://github.com/panosoft/spawn-promise
    var child = childProcess.spawn( command, args )

    // Capture errors
    var errors = {}
    child.on( 'error', error => errors.spawn = error )
    child.stdin.on( 'error', error => errors.stdin = error )
    child.stdout.on( 'error', error => errors.stdout = error )
    child.stderr.setEncoding( 'utf8' )
    child.stderr.on( 'error', error => errors.stderr = error )
    child.stderr.on( 'data', data => {
        if ( !errors.process ) errors.process = ''
        errors.process += data
    })

    // Capture output
    var buffers = []
    child.stdout.on( 'data', data => buffers.push( data ))

    // input
    child.stdin.write( input )
    child.stdin.end()

    // Run
    await new Promise(( resolve, reject ) => {
        child.on( 'close', ( code, signal ) => {
            if ( code !== 0 ) {
                reject( new Error( `Command failed: ${ code } ${ JSON.stringify( errors ) }` ))
            } else {
                resolve()
            }
        })
        child.stdin.end( input )
    })

    //~ if ( Object.keys( errors ).length !== 0 )
        //~ return Promise.reject( new Error( JSON.stringify( errors )))

    return Buffer.concat( buffers )
}

function cvsReader ( path, options ) {
    let finished = false
    const inp = fs.createReadStream( path )
    const parser = csvParse( options )

    parser.on( 'error', function ( err ) {
        console.error( 'cvsReader ' + err.message )
        throw err
    })
    parser.on( 'end', function () {
        log( 'cvsReader end', path )
        finished = true
        parser.emit( 'readable' )
    })

    log( 'cvsReader start', path )
    inp.pipe( parser )

    function getRow () {
        return new Promise( resolve => {
            const row = parser.read()
            if ( row || finished ) {
                resolve( row )
            } else {
                parser.once( 'readable', () => resolve( getRow()))
            }
        })
    }

    return getRow
}

//
// Writer
//
class Writer {
    constructor ( path ) {
        this.position = BigInt( 0 )
        this.stream = fs.createWriteStream( path, { highWaterMark: 1024*1024*10 })
        this.stream.once( 'open', fd => { })
        this.stream.on( 'error', err => {
            fatal( 'Writer error', this.stream.path, err )
        })

        this.queue = genericPool.createPool(
            {
                async create () { return Symbol() },
                async destroy ( resource ) { return true },
            },
            {}
        )
    }

    async write ( data ) {
        const token = await this.queue.acquire()
        const startPosition =  this.position
        this.position += BigInt( data.length )

        const saturated = ! this.stream.write( data )
        if ( saturated ) {
            this.stream.once( 'drain', () => this.queue.release( token ))
        } else {
            this.queue.release( token )
        }
        return startPosition
    }

    async close () {
        await this.queue.drain()
        return await new Promise( resolve => {
            this.queue.clear()
            this.stream.once( 'close', () => {
                log( this.stream.path, 'closed', this.position, this.stream.bytesWritten )
                resolve( this.position )
            })
            log( 'closing', this.stream.path )
            this.stream.end()
        })
    }
}

//
// Cluster
//

// var ClusterSizeThreshold = 8 * 1024 * 1024
//~ var ClusterSizeThreshold = 4 * 1024 * 1024
var ClusterSizeThreshold = 1 * 1024 * 1024
// var ClusterSizeThreshold = 2 * 1024 * 1024

class Cluster {
    constructor ( compressible ) {
        this.id = header.clusterCount ++
        this.compressible = compressible
        this.blobs = []
        this.size = 0
    }

    append ( data ) {
        var id = this.id
        var blobNum = this.blobs.length
        if ( blobNum != 0 && this.size + data.length > ClusterSizeThreshold )
            return false

        this.blobs.push( data )
        this.size += data.length
        return blobNum
    }

    // Cluster
    // Field Name          Type    Offset  Length  Description
    // compression type    integer     0   1   0: default (no compression), 1: none (inherited from Zeno), 4: LZMA2 compressed
    // The following data bytes have to be uncompressed!
    // <1st Blob>          integer     1   4   offset to the <1st Blob>
    // <2nd Blob>          integer     5   4   offset to the <2nd Blob>
    // <nth Blob>          integer     (n-1)*4+1   4   offset to the <nth Blob>
    // ...                 integer     ...     4   ...
     // <last blob / end>   integer     n/a     4   offset to the end of the cluster
    // <1st Blob>          data        n/a     n/a     data of the <1st Blob>
    // <2nd Blob>          data        n/a     n/a     data of the <2nd Blob>
    // ...                 data        ...     n/a     ...

    async getData () {
        //~ log( 'Cluster.prototype.save', this.compressible, this.blobs )

        // generate blob offsets
        const byteLength = 4
        let blobOffset = ( this.blobs.length + 1 ) * byteLength
        const offsetIndex = this.blobs.map(( blob, i, arr ) => {
            const val = [ blobOffset, byteLength ]
            blobOffset += blob.length
            return val
        })
        offsetIndex.push([ blobOffset, byteLength ]) // final offset

        const chunks = offsetIndex.concat( this.blobs )

        let data = chunksToBuffer( chunks )

        if ( this.compressible ) {
            // https://tukaani.org/lzma/benchmarks.html
            // https://catchchallenger.first-world.info/wiki/Quick_Benchmark:_Gzip_vs_Bzip2_vs_LZMA_vs_XZ_vs_LZ4_vs_LZO
            data = await lzma.compress( data, 5 ) // 3 | lzma.PRESET_EXTREME )
            log( 'Cluster lzma compressed' )
        }

        const compression = toBuffer( this.compressible ? 4 : 0, 1 )

        return Buffer.concat([ compression, data ])
    }
}

//
// ClusterPool
//
class ClusterPool {
    constructor () {
        this.holder = {}
        this.savePrefix = outPath + '.tmp'
        this.pool = genericPool.createPool(
            {
                async create () { return Symbol() },
                async destroy ( resource ) { return true },
            },
            { max: 8, }
        )
    }

    removeCluster ( type ) {
        delete this.holder[ type ]
    }

    getCluster ( type ) {
        let cluster = this.holder[ type ]
        if ( ! cluster )
            cluster = this.holder[ type ] = new Cluster( type )
        return cluster
    }

    async save ( cluster ) {
        const data = await cluster.getData()
        const row = [ cluster.id ]
        if ( ! command.zimlib4Fix ) { 
            const offset = await out.write( data )
            row.push( offset.toString() ) // convert BigInt to String
        } else { // zimlib4Fix stores clusters in separate files
            await fs.outputFile( osPath.join( this.savePrefix, `${cluster.id}` ), data )
            row.push( data.length ) // cluster sizes instead of offsets
        }
        await wikiDb.run( 'INSERT INTO clusters ( id, offset ) VALUES ( ?,? )', row )
        log( 'Cluster saved', row )
    }

    async append ( mimeType, data, path /* for debugging */ ) {
        var compressible = this.isCompressible( mimeType, data, path )
        var cluster = this.getCluster( compressible )
        var clusterNum = cluster.id
        var blobNum = cluster.append( data )

        if ( blobNum === false ) { // save current cluster, create and store into a new cluster
            this.removeCluster( compressible )
            const token = await this.pool.acquire()

            await this.save( cluster )
            this.pool.release( token )

            return this.append( mimeType, data, path )
        }

        log( 'ClusterWriter.append', compressible, clusterNum, blobNum, data.length, path )
        return [ clusterNum, blobNum ]
    }

    isCompressible ( mimeType, data, id ) {
        if ( ! command.compress )
            return false
        if ( data == null || data.length == 0 )
            return false
        if ( !mimeType ) {
            fatal( 'isCompressible !mimeType', mimeType, data, id )
        }
        if ( mimeType == 'image/svg+xml' || mimeType.split( '/' )[ 0 ] == 'text' )
            return true
        return !! ( mimeDb[ mimeType ] && mimeDb[ mimeType ].compressible )
    }

    // The cluster pointer list is a list of 8 byte offsets which point to all data clusters in a ZIM file.
    // Field Name  Type    Offset  Length  Description
    // <1st Cluster>   integer     0   8   pointer to the <1st Cluster>
    // <1st Cluster>   integer     8   8   pointer to the <2nd Cluster>
    // <nth Cluster>   integer     (n-1)*8     8   pointer to the <nth Cluster>
    // ...     integer     ...     8   ...

    async storeIndex () {
        const byteLength = 8
        const count = header.clusterCount        
        let rowCb = ( row, index ) => BigInt( row.offset )
        
        if ( command.zimlib4Fix ) {
            let offsetZimlib4 = await out.write( Buffer.alloc( 0 )) + BigInt( count * byteLength )                
            rowCb = ( row, index ) => { 
                    const val = offsetZimlib4
                    offsetZimlib4 += BigInt( row.offset )
                    return val
                }
        }

        header.clusterPtrPos = await saveIndex ({
            query:`
                SELECT
                    CAST( offset AS TEXT ) AS offset -- to prevent casting to JS Number
                FROM clusters
                ORDER BY id
                ;`,
            byteLength,
            count,
            logPrefix: 'storeClusterIndex',
            rowCb,
        })
    }

    async storeClusters () {
        if ( command.zimlib4Fix ) { // zimlib4Fix stores clusters in separate files
            for ( let i = 0; i < header.clusterCount; i++ ) {
                const fname = osPath.join( this.savePrefix, `${i}` )
                const data = await fs.readFile( fname )
                const pos = await out.write( data )
                log( 'storeClusters', i, pos )
                await fs.remove( fname )
            }
            await fs.remove( this.savePrefix )
        }
    }

    async finish () {
        //~ log( 'ClusterWriter.finish', ClusterWriter )
        for ( let i in this.holder ) { // save last clusters
            await this.save( this.holder[ i ] )
        }
        await this.pool.drain()
        await this.pool.clear()
        await this.storeIndex()
        await this.storeClusters()
        return
    }
}

class NoProcessingRequired extends Error {
    // For non-error promise rejection
}

//
// Item
//
class Item {
    constructor ( params ) {
        Object.assign( this, {
            nameSpace: null,
            path: null,
            title: '',
            mimeType: null,
            revision: 0,
            dirEntry: null,
            id: null,
        })
        Object.assign( this, params )
    }

    process () {
        //~ log( 'Item process', this.path )

        return this.storeDirEntry()
    }

    urlKey () {
        return this.nameSpace + this.path
    }

    titleKey () {
        return this.nameSpace + ( this.title || this.path )
    }

    mimeId () {
        return mimeTypeIndex( this.mimeType )
    }

    async getId () {
        if ( ! this.id )
            this.id = this.saveItemIndex()
        return await this.id
    }

    async saveItemIndex () {
        if ( ! this.path ) {
            fatal( 'Item no url', this )
        }
        const row = [
            this.urlKey(),
            this.titleKey(),
            this.revision,
            this.mimeId(),
        ]
        const result = await wikiDb.run(
            'INSERT INTO articles ( urlKey, titleKey, revision, mimeId ) VALUES ( ?,?,?,? )',
            row
        )
        const id = result.stmt.lastID
        log( 'saveItemIndex', id, this )
        return id
    }

    // Article Entry
    // Field Name      Type    Offset  Length  Description
    // mimetype        integer     0   2   MIME type number as defined in the MIME type list
    // parameter       len byte    2   1   (not used) length of extra paramters
    // namespace       char        3   1   defines to which namespace this directory entry belongs
    // revision        integer     4   4   (optional) identifies a revision of the contents of this directory entry, needed to identify updates or revisions in the original history
    // cluster number  integer     8   4   cluster number in which the data of this directory entry is stored
    // blob number     integer     12  4   blob number inside the compressed cluster where the contents are stored
    // url             string      16  zero terminated     string with the URL as refered in the URL pointer list
    // title           string      n/a     zero terminated     string with an title as refered in the Title pointer list or empty; in case it is empty, the URL is used as title
    // parameter       data        see parameter len   (not used) extra parameters

    async storeDirEntry ( clusterIdx, blobIdx, redirectTarget ) {
        if ( clusterIdx == null ) {
            fatal( 'storeDirEntry error: clusterIdx == null', this )
            return
        }
        header.articleCount++
        const mimeId = this.mimeId()
        log( 'storeDirEntry', mimeId, this )
        const chunks = [
            [ mimeId, 2 ],
            [ 0, 1 ], // parameters length
            this.nameSpace,
            [ this.revision, 4 ],
            [ clusterIdx || redirectTarget || 0, 4 ], // or redirect target article index
            redirectTarget == null ? [ blobIdx, 4 ] : '', // if not a redirect
            this.path + '\0',
            this.title + '\0',
        ]

        this.dirEntryOffset = await out.write( chunksToBuffer( chunks ))
        log( 'storeDirEntry done', this.dirEntryOffset, this.path )
        return await this.saveDirEntryIndex()
    }

    async saveDirEntryIndex ( ) {
        const id = await this.getId()
        try {
            log( 'saveDirEntryIndex', id, this.dirEntryOffset, this.path )
            return await wikiDb.run(
                'INSERT INTO dirEntries (id, offset) VALUES (?,?)',
                [
                    id,
                    this.dirEntryOffset.toString(), // BigInt -> String
                ]
            )
        } catch ( err ) {
            fatal( 'saveDirEntryIndex error', err, this )
        }
    }
}

//
// class LinkTarget
//
class LinkTarget extends Item {
    constructor ( id, path, nameSpace, title ) {
        super({
            id,
            path,
            nameSpace,
            title,
            mimeType: LINKTARGET_MIME,
        })
        log( 'LinkTarget', nameSpace, path, this )
    }

    storeDirEntry () {
        return super.storeDirEntry( 0, 0 )
    }
}

//
// class DeletedEntry
//
class DeletedEntry extends Item {
    constructor ( id, path, nameSpace, title ) {
        super({
            id,
            path,
            nameSpace,
            title,
            mimeType: DELETEDENTRY_MIME,
        })
        log( 'DeletedEntry', nameSpace, path, this )
    }
    storeDirEntry () {
        return super.storeDirEntry( 0, 0 )
    }
}

//
// class TargetItem
//
class TargetItem extends Item {
    constructor ( params ) {
        params.fragment = params.fragment === undefined ? null : params.fragment;
        super( params )
    }
}

//
// class Redirect
//
class Redirect extends Item {
    constructor ( params ) {
        // params: path, nameSpace, title, to, revision
        // to: path, nameSpace, fragment
        let to = params.to
        delete params.to

        params.mimeType = REDIRECT_MIME

        super( params )

        if ( typeof to == 'string' )
            to = { path: to }
        to.nameSpace = to.nameSpace || this.nameSpace

        this.target = new TargetItem( to )
        log( 'Redirect', this.nameSpace, this.path, to, this )
    }

    process () {
        return this.saveRedirectIndex()
    }

    async saveRedirectIndex () {
        const id = await this.getId()
        return wikiDb.run(
            'INSERT INTO redirects (id, targetKey, fragment) VALUES (?,?,?)',
            [
                id,
                this.target.urlKey(),
                this.target.fragment,
            ]
        )
    }
}

//
// class ResolvedRedirect
//
class ResolvedRedirect extends Item {
    constructor ( id, nameSpace, path, title, target, revision ) {
        super({
            path,
            nameSpace,
            title,
            mimeType: REDIRECT_MIME,
            revision,
        })
        this.target = target
        this.id = id
    }

    storeDirEntry () {
        // Redirect Entry
        // Field Name      Type    Offset  Length  Description
        // mimetype        integer 0       2       0xffff for redirect
        // parameter len   byte    2       1       (not used) length of extra paramters
        // namespace       char    3       1       defines which namespace this directory entry belongs to
        // revision        integer 4       4       (optional) identifies a revision of the contents of this directory entry, needed to identify updates or revisions in the original history
        // redirect index  integer 8       4       pointer to the directory entry of the redirect target
        // url             string  12      zero terminated     string with the URL as refered in the URL pointer list
        // title           string  n/a     zero terminated     string with an title as refered in the Title pointer list or empty; in case it is empty, the URL is used as title
        // parameter       data    see parameter len   (not used) extra parameters

        // redirect dirEntry shorter on 4 byte field
        return super.storeDirEntry( 0, 0, this.target )
    }
}

//
// DataItem
//
class DataItem extends Item {
    constructor ( params ) {
        params.data = params.data === undefined ? null : params.data;
        super( params )
    }

    async process () {
        //~ log( 'DataItem process', this.path )
        try {
            await this.store()
            await super.process()
        } catch ( err ) {
            if ( err instanceof NoProcessingRequired )
                return
            fatal( 'Item process error', this.path, err )
        }
    }

    async store () {
        let data = await this.getData()
        if ( data == null ) {
            fatal( 'DataItem.store error: data == null', this )
        }
        if ( !( data instanceof Buffer )) {
            data = Buffer.from( data )
        }
        const [ clusterIdx, blobIdx ] = await clusterWriter.append( this.mimeType, data, this.path )
        Object.assign( this, { clusterIdx, blobIdx })
    }

    async getData () {
        return await this.data
    }

    storeDirEntry () {
        return super.storeDirEntry( this.clusterIdx, this.blobIdx )
    }
}

//
// class File
//
class File extends DataItem {
    //~ id ,
    //~ mimeId ,
    //~ revision ,
    //~ urlKey ,
    //~ titleKey
    async getData () {
        if ( this.data == null ) {
            this.data = fs.readFile( this.srcPath())
        }
        const data = await this.data
        return await this.preProcess( data )
    }

    srcPath () {
        return fullPath( this.nameSpace + '/' + this.path )
    }

    preProcess ( data ) {
        switch ( this.mimeType ) {
            case 'image/jpeg':
                return this.processJpeg( data )
            //~ case 'image/gif':
            case 'image/png':
                return this.processImage( data )
            default:
                return data
        }
    }

    async processJpeg ( data ) {
        if ( ! command.optimg )
            return data
        this.mimeType = 'image/jpeg'
        try {
            return await spawn(
                mozjpeg,
                [ '-quality', command.jpegquality, data.length < 20000 ? '-baseline' : '-progressive' ],
                data
            )
        } catch ( err ) {
            log( 'Error otimizing jpeg', err, this )
            return data
        }
    }

    async processImage ( data ) {
        if ( ! command.optimg )
            return data
        try {
            const image = sharp( data )
            const metadata = await image.metadata()
            if ( metadata.format == 'gif' && isAnimated( data )) {
                return data
            }
            if ( metadata.hasAlpha && metadata.channels == 1 ) {
                log( 'metadata.channels == 1', this.path )
            } else if ( metadata.hasAlpha && metadata.channels > 1 ) {
                if ( data.length > 20000 ) {
                    // Is this rather opaque?
                    const alpha = await image
                        .clone()
                        .extractChannel( metadata.channels - 1 )
                        .raw()
                        .toBuffer()

                    const opaqueAlpha = Buffer.alloc( alpha.length, 0xff )
                    const isOpaque = alpha.equals( opaqueAlpha )

                    if ( isOpaque ) { // convert to JPEG
                        log( 'isOpaque', this.path )
                        if ( metadata.format == 'gif' )
                            data = await image.toBuffer()
                        return this.processJpeg ( data )
                    }
                }
            }
            if ( metadata.format == 'gif' )
                return data
            return await image.toBuffer() // so to catch an error
        } catch ( err ) {
            log( 'Error otimizing image', err, this )
            return data
        }
    }
}

//
// class RawFile
//
class RawFile extends File {
    constructor ( path ) {
        const mimeType = mimeFromPath( path )
        const nameSpace = getNameSpace( mimeType )
        super({
            path,
            mimeType,
            nameSpace,
        })
    }

    srcPath () {
        return fullPath( this.path )
    }

    async preProcess ( data ) {
        if ( ! this.mimeType ) {
            this.mimeType = await mimeFromData( data )
            this.nameSpace = this.nameSpace || getNameSpace( this.mimeType )
        }
        if ( command.inflateHtml && this.mimeType == 'text/html' ) {
            data = await zlib.inflate( data ) // inflateData
        }
        await this.preProcessHtml( data )
        return super.preProcess( data )
    }

    async preProcessHtml ( data ) {
        const dom = ( this.mimeType == 'text/html' ) && cheerio.load( data.toString())
        if ( dom ) {
            const title = dom( 'title' ).text()
            this.title = this.title || title
            const redirectTarget = this.isRedirect( dom )
            if ( redirectTarget ) { // convert to redirect
                const redirect = new Redirect({
                    path: this.path,
                    nameSpace: this.nameSpace,
                    title: this.title,
                    to: redirectTarget,
                })
                await redirect.process()
                return Promise.reject( new NoProcessingRequired())
            }
            if ( this.alterLinks( dom ))
                data = Buffer.from( dom.html())
        }
        return data
    }

    alterLinks ( dom ) {
        var base = '/' + this.path
        var nsBase = '/' + this.nameSpace + base
        var baseSplit = nsBase.split( '/' )
        var baseDepth = baseSplit.length - 1
        var changes = 0

        function toRelativeLink ( elem, attr ) {
            try {
                var link = url.parse( elem.attribs[ attr ], true, true )
            } catch ( err ) {
                console.warn( 'alterLinks error', err.message, elem.attribs[ attr ], 'at', base )
                return
            }
            var path = link.pathname
            if ( link.protocol || link.host || ! path )
                return
            var nameSpace = getNameSpace( mimeFromPath( path ))
            if ( ! nameSpace )
                return

            // convert to relative path
            var absPath = '/' + nameSpace + url.resolve( base, path )
            var to = absPath.split( '/' )
            var i = 0
            for ( ; baseSplit[ i ] === to[ 0 ] && i < baseDepth; i++ ) {
                to.shift()
            }
            for ( ; i < baseDepth; i++ ) {
                to.unshift( '..' )
            }
            var relPath = to.join( '/' )
            //~ log( 'alterLinks', nsBase, decodeURI( path ), decodeURI( absPath ), decodeURI( relPath ))

            link.pathname = relPath
            elem.attribs[ attr ] = url.format( link )

            changes ++
            return
        }

        ['src', 'href'].map( attr => {
            dom( '['+attr+']' ).each( (index, elem) => toRelativeLink ( elem, attr ))
        })

        log( 'alterLinks', changes )

        return changes > 0
    }

    isRedirect ( dom ) {
        var content = dom( 'meta[http-equiv="refresh"]' ).attr( 'content' )
        if ( content == null )
            return null
        var splited = content.split( ';' )
        if ( ! splited[ 1 ] )
            return null

        log( 'File.prototype.getRedirect', this.path, splited)
        var link = url.parse( splited[ 1 ].split( '=', 2 )[ 1 ], true, true )
        if ( link.protocol || link.host || ! link.pathname || link.pathname[ 0 ] =='/' )
            return null

        var target = {
            path: decodeURIComponent( link.pathname ),
            fragment: link.hash,
        }
        return target
    }
}

//
// General functions
//

// Keys
// Key             Mandatory   Description     Example
//
// Name         yes     A human readable identifier for the resource. It's the same across versions (should be stable across time). MUST be prefixed by the packager name.  kiwix.wikipedia_en.nopics
// Title        yes     title of zim file   English Wikipedia
// Creator      yes     creator(s) of the ZIM file content  English speaking Wikipedia contributors
// Publisher    yes     creator of the ZIM file itself  Wikipedia user Foobar
// Date         yes     create date (ISO - YYYY-MM-DD)  2009-11-21
// Description  yes     description of content  This ZIM file contains all articles (without images) from the english Wikipedia by 2009-11-10.
// Language     yes     ISO639-3 language identifier (if many, comma separated)     eng
// Tags         no      A list of tags  nopic;wikipedia
// Relation     no      URI of external related ressources
// Source       no      URI of the original source  http://en.wikipedia.org/
// Counter      no      Number of non-redirect entries per mime-type    image/jpeg=5;image/gif=3;image/png=2;...
//
// Favicon a favicon (48x48) is also mandatory and should be located at /-/favicon

function fillInMetadata () {
    const outParsed = osPath.parse( outPath )
    const metadata = [
        [ 'Name', outParsed.base ],
        [ 'Title', command.title ],
        [ 'Creator', command.creator ],
        [ 'Publisher', command.publisher ],
        [ 'Date', new Date().toISOString().split( 'T' )[ 0 ]],
        [ 'Description', command.description ],
        [ 'Language', command.language ],
        [ 'logo', command.favicon ],
        //~ [ 'mainpage', command.welcome ],
    ]

    const done = []
    metadata.forEach( item => {
        var article
        var name = item[ 0 ]
        var val = item[ 1 ]
        switch ( name ) {
            case 'mainpage':
                article  = mainPage = new Redirect({
                    path: 'mainpage',
                    nameSpace: '-',
                    to: { path: val, nameSpace: 'A' }
                })
                break
            case 'logo':
                article  = new Redirect({
                    path: 'favicon',
                    nameSpace: '-',
                    to: { path: val, nameSpace: 'I' }
                })
                break
            default:
                article = new DataItem({
                    path: name,
                    mimeType: 'text/plain',
                    nameSpace: 'M',
                    data: val
                })
        }
        done.push( article.process())
    })

    return Promise.all( done )
}

async function openWikiDb( dbName ) {
    wikiDb = await sqlite.open( dbName )
    return wikiDb.exec(`
        PRAGMA synchronous = OFF;
        PRAGMA journal_mode = WAL;
        DROP INDEX IF EXISTS articleUrlKey ;
        DROP INDEX IF EXISTS urlSortedArticleId ;
        DROP INDEX IF EXISTS articleTitleKey ;

        DROP TABLE IF EXISTS urlSorted ;
        DROP TABLE IF EXISTS dirEntries ;
        DROP TABLE IF EXISTS clusters ;

        CREATE TABLE dirEntries (
            id INTEGER PRIMARY KEY,
            offset INTEGER
            );
        CREATE TABLE clusters (
            id INTEGER PRIMARY KEY,
            offset INTEGER
            );
        `
    )
}

async function newWikiDb() {
    var dbName = ''
    if ( command.verbose ) {
        var parsed = osPath.parse( outPath )
        dbName = osPath.join( parsed.dir, parsed.base + '.db' )
    }
    try {
        await fs.unlink( dbName )
    } catch ( err ) {
    }
    wikiDb = await sqlite.open( dbName )
    return wikiDb.exec(
        'PRAGMA synchronous = OFF;' +
        'PRAGMA journal_mode = OFF;' +
        //~ 'PRAGMA journal_mode = WAL;' +
        'CREATE TABLE articles (' + [
                'id INTEGER PRIMARY KEY',
                'mimeId INTEGER',
                'revision INTEGER',
                'mwId INTEGER',
                'urlKey TEXT',
                'titleKey TEXT',
            ].join(',') +
            ');' +
        'CREATE TABLE redirects (' +
            'id INTEGER PRIMARY KEY,' +
            'targetKey TEXT, ' +
            'fragment TEXT ' +
            ');' +
        'CREATE TABLE dirEntries (' +
            'id INTEGER PRIMARY KEY,' +
            'offset INTEGER' +
            ');' +
        'CREATE TABLE clusters (' +
            'id INTEGER PRIMARY KEY,' +
            'offset INTEGER ' +
            ');'
    )
}

function sortArticles () {
    return wikiDb.exec(`
        CREATE INDEX articleUrlKey ON articles (urlKey);

        CREATE TABLE urlSorted AS
            SELECT
                id,
                urlKey
            FROM articles
            ORDER BY urlKey;

        CREATE INDEX urlSortedArticleId ON urlSorted (id);

        CREATE INDEX articleTitleKey ON articles (titleKey);
        `
    )
}

async function csvRedirects () {
    const csv = command.redirects ? 
        expandHomeDir( command.redirects ) :
        osPath.join( srcPath, 'redirects.csv' )

    if ( ! await fs.exists( csv )) 
        return

    const getRow = cvsReader( csv, {
        columns:[ 'nameSpace', 'path', 'title', 'to' ],
        delimiter: '\t',
        relax_column_count: true
    })

    let row
    while ( row = await getRow() ) {
        log( 'csvRedirects', row )
        await new Redirect( row ).process()
    }
}

async function resolveRedirects () {
    var stmt = await wikiDb.prepare( `
        SELECT
            src.id AS id,
            src.urlKey AS urlKey,
            src.titleKey AS titleKey,
            src.revision AS revision,
            targetKey,
            targetRow,
            targetId
        FROM (
            SELECT
                *,
                urlSorted.rowid AS targetRow
            FROM (
                SELECT
                    redirects.id AS id,
                    redirects.targetKey AS targetKey,
                    dst.id AS targetId
                FROM redirects
                LEFT OUTER JOIN articles AS dst
                ON redirects.targetKey = dst.urlKey
            ) AS fromTo
            LEFT OUTER JOIN urlSorted
            ON fromTo.targetId = urlSorted.id
        ) AS dstResolved
        JOIN articles AS src
        USING (id)
        -- WHERE targetId IS NOT NULL
        ;`)
    let row
    while ( row = await stmt.get() ) {
        const nameSpace = row.urlKey[ 0 ]
        const path = row.urlKey.substr( 1 )
        const title = ( row.titleKey == row.urlKey ) ? '' : row.titleKey.substr( 1 )
        if ( row.targetRow == null ) { // unresolved redirect
            await new DeletedEntry( row.id, path, nameSpace, title ).process() // Linktarget
        } else {
            await new ResolvedRedirect ( row.id, nameSpace, path, title, row.targetRow - 1, row.revision ).process()
        }
    }
    return stmt.finalize()
}

async function saveIndex ( params ) {
    const logPrefix = params.logPrefix || 'saveIndex'
    const stmt = await wikiDb.prepare( params.query )
    let startOffset
    let i = 0
    for ( let row; row = await stmt.get(); i++ ) {
        const val = params.rowCb( row, i )
        log( logPrefix, i, val, row )
        const offset = await out.write( toBuffer( val, params.byteLength ))
        if ( ! startOffset )
            startOffset = offset
    }
    await stmt.finalize()

    log( logPrefix, 'done', i, params.count, startOffset )
    return startOffset
}

// URL Pointer List (urlPtrPos)

// The URL pointer list is a list of 8 byte offsets to the directory entries.

// The directory entries are always ordered by URL (including the namespace prefix). Ordering is simply done by comparing the URL strings in binary.

// Since directory entries have variable sizes this is needed for random access.
// Field Name  Type    Offset  Length  Description
// <1st URL>   integer     0   8   pointer to the directory entry of <1st URL>
// <2nd URL>   integer     8   8   pointer to the directory entry of <2nd URL>
// <nth URL>   integer     (n-1)*8     8   pointer to the directory entry of <nth URL>
// ...     integer     ...     8   ...

async function storeUrlIndex () {
    header.urlPtrPos = await saveIndex ({
        query:`
            SELECT
                urlSorted.rowid,
                id,
                urlKey,
                CAST( offset AS TEXT ) AS offset -- to prevent casting to JS Number
            FROM urlSorted
            LEFT OUTER JOIN dirEntries
            USING (id)
            ORDER BY urlSorted.rowid
            ;`,
        byteLength: 8,
        count: header.articleCount,
        logPrefix: 'storeUrlIndex',
        rowCb: ( row, index ) => {
            return BigInt( row.offset )
        }
    })
}

// Title Pointer List (titlePtrPos)

// The title pointer list is a list of article indices ordered by title. The title pointer list actually points to entries in the URL pointer list. Note that the title pointers are only 4 bytes. They are not offsets in the file but article numbers. To get the offset of an article from the title pointer list, you have to look it up in the URL pointer list.
// Field Name      Type        Offset  Length  Description
// <1st Title>     integer     0       4       pointer to the URL pointer of <1st Title>
// <2nd Title>     integer     4       4       pointer to the URL pointer of <2nd Title>
// <nth Title>     integer     (n-1)*4 4       pointer to the URL pointer of <nth Title>
// ...             integer     ...     4       ...

async function storeTitleIndex () {
    header.titlePtrPos = await saveIndex ({
        query: `
            SELECT
                titleKey,
                urlSorted.rowid - 1 AS urlIndex
            FROM urlSorted
            JOIN articles
            USING (id)
            ORDER BY titleKey
            ;`,
        byteLength: 4,
        count: header.articleCount,
        logPrefix: 'storeTitleIndex',
        rowCb: ( row, index ) => {
            if ( row.titleKey == mainPage.titleKey )
                mainPage.index = row.urlIndex
            return row.urlIndex
        }
    })
}

// MIME Type List (mimeListPos)

// The MIME type list always follows directly after the header, so the mimeListPos also defines the end and size of the ZIM file header.

// The MIME types in this list are zero terminated strings. An empty string marks the end of the MIME type list.
// Field Name          Type    Offset  Length  Description
// <1st MIME Type>     string  0       zero terminated     declaration of the <1st MIME Type>
// <2nd MIME Type>     string  n/a     zero terminated     declaration of the <2nd MIME Type>
// ...                 string  ...     zero terminated     ...
// <last entry / end>  string  n/a     zero terminated     empty string - end of MIME type list

function getMimeTypes () {
    var buf = Buffer.from( mimeTypeList.join( '\0' ) + '\0\0' )
    log( 'MimeTypes', mimeTypeList.length, buf.length )

    if ( buf.length > maxMimeLength ) {
        fatal( 'Error: mime type list length >', maxMimeLength )
    }
    return buf
}

function getHeader () {
    header.mainPage = mainPage.index || header.mainPage

    //~ log( 'Header', 'articleCount', header.articleCount, 'clusterCount', header.clusterCount, 'mainPage', mainPage )
    log( 'Header', header )

    const chunks = [
        [ header.magicNumber,    4 ],
        [ header.versionMajor,   2 ],
        [ header.versionMinor,   2 ],

        header.uuid,

        [ header.articleCount,   4 ],
        [ header.clusterCount,   4 ],

        [ header.urlPtrPos,      8 ],
        [ header.titlePtrPos,    8 ],
        [ header.clusterPtrPos,  8 ],
        [ header.mimeListPos,    8 ],

        [ header.mainPage,       4 ],
        [ header.layoutPage,     4 ],

        [ header.checksumPos,    8 ],
    ]

    return chunksToBuffer( chunks )
}

async function storeHeader() {
    var buf = Buffer.concat([ getHeader(), getMimeTypes() ])
    var fd = await fs.open( outPath, 'r+' )
    await fs.write( fd, buf, 0, buf.length, 0 )
    return fs.close( fd )
}

function calculateFileHash () {
    var outHash
    var hash = crypto.createHash( 'md5' )
    var stream = fs.createReadStream( outPath )

    stream.on( 'data', data => hash.update( data ))

    return new Promise( (resolve, reject ) => stream.on( 'end', async () => {
        outHash = hash.digest()
        await fs.appendFile( outPath, outHash )
        log( 'outHash', outHash )
        resolve()
    }))
}

async function initialise () {
    clusterWriter = new ClusterPool

    var stat = await fs.stat( srcPath )
    if ( ! stat.isDirectory() ) {
        throw new Error( srcPath + ' is not a directory' )
    }

    out = new Writer( outPath ); // create output file
    log( 'reserving space for header and mime type list' )
    await out.write( Buffer.alloc( headerLength + maxMimeLength ))
    
    if ( command.main ) {
        mainPage.titleKey = 'A' + command.main
    } 

    var dbPath = osPath.join( srcPath, 'metadata.db' )
    let preProcessed = false
    if ( await fs.exists( dbPath )) {
        preProcessed = true
        try {
            mainPage.titleKey = mainPage.titleKey ||
                ( 'A' + ( await fs.readFile( osPath.join( srcPath, 'M', 'mainpage' ))).toString())
        } catch ( err ) {
            warning( 'mainpage error', err )
        }
        await openWikiDb( dbPath )
        await loadMimeTypes()
    } else {
        await newWikiDb()
        await fillInMetadata()
    }
    return preProcessed
}

async function rawLoader () {
    const dirs = [ '' ]

    async function parseDirEntry ( path ) {
        if ( path == 'metadata.csv' || path == 'redirects.csv' )
            return

        const stats = await fs.lstat( fullPath( path ))
        if ( stats.isDirectory())
            return dirs.push( path )
        if ( stats.isFile() || stats.isSymbolicLink()) {
            return new RawFile( path ).process()
        }
        throw new Error( 'Invalid dir entry ' + absPath )
    }

    log( 'rawLoader start' )
    // scan Directories
    for ( let path; ( path = dirs.shift()) != null; ) {
        log( 'scanDirectory', path )

        const dirlist = await fs.readdir( fullPath( path ))
        for ( let fname of dirlist ) {
            await parseDirEntry( osPath.join( path, fname ))
        }
    }

    log( 'rawLoader finished !!!!!!!!!' )
}

async function loadPreProcessedArticles () {
    var stmt = await wikiDb.prepare( `
        SELECT
            id ,
            mimeId ,
            revision ,
            urlKey ,
            titleKey
        FROM articles
        WHERE mimeId IS NOT 0xffff
        ;`)
    while ( true ) {
        const row = await stmt.get()
        if ( ! row ) {
            break
        }
        var nameSpace = row.urlKey[ 0 ]
        var path = row.urlKey.substr( 1 )
        var title = ( row.titleKey == row.urlKey ) ? '' : row.titleKey.substr( 1 )
        await new File( {
            nameSpace,
            path,
            title,
            mimeType: mimeFromIndex( row.mimeId ),
            id: row.id,
            revision: row.revision,
        } )
        .process()
    }
    return stmt.finalize()
}

async function loadMimeTypes () {
    var stmt = await wikiDb.prepare( `
        SELECT
            id ,
            value
        FROM mimeTypes
        ORDER BY id
        ;`)
    while ( true ) {
        const row = await stmt.get()
        if ( ! row ) {
            break
        }
        mimeTypeList.push( row.value )
    }
    return stmt.finalize()
}

async function loadRawArticles () {
    await rawLoader()
    return csvRedirects()
}

async function postProcess () {
    await sortArticles()
    await resolveRedirects()
    await storeUrlIndex()
    await storeTitleIndex()
    await clusterWriter.finish()
    return
}

async function finalise () {
    header.checksumPos = await out.close() // close the output stream
    await wikiDb.close()
    await storeHeader()
    return calculateFileHash()
}

async function core () {
    const preProcessed = await initialise()
    await ( preProcessed ? loadPreProcessedArticles() : loadRawArticles() )
    await postProcess()
    await finalise()
}

// Mandatory arguments:
// -w, --welcome           path of default/main HTML page. The path must be relative to HTML_DIRECTORY.
// -f, --favicon           path of ZIM file favicon. The path must be relative to HTML_DIRECTORY and the image a 48x48 PNG.
// -l, --language          language code of the content in ISO639-3
// -t, --title             title of the ZIM file
// -d, --description       short description of the content
// -c, --creator           creator(s) of the content
// -p, --publisher         creator of the ZIM file itself

// HTML_DIRECTORY          is the path of the directory containing the HTML pages you want to put in the ZIM file,
// ZIM_FILE                is the path of the ZIM file you want to obtain.

// Optional arguments:
// -v, --verbose           print processing details on STDOUT
// -h, --help              print this help
// -m, --minChunkSize      number of bytes per ZIM cluster (defaul: 2048)
// -x, --inflateHtml       try to inflate HTML files before packing (*.html, *.htm, ...)
// -u, --uniqueNamespace   put everything in the same namespace 'A'. Might be necessary to avoid problems with dynamic/javascript data loading.
// -r, --redirects         path to the CSV file with the list of redirects (url, title, target_url tab separated).
// -i, --withFullTextIndex index the content and add it to the ZIM.

async function main () {

    command
    .version( packageInfo.version )
    .arguments( '<source-directory> [<output-file>]' )
    .description( `Pack a directory into a zim file

  Where:
    source-directory \t path to the directory with HTML pages to pack into a ZIM file
    zim-file \t\t optional path for the output` )
    // zimmer options:
    .option( '--optimg', 'optimise images' )
    .option( '--jpegquality <factor>', 'JPEG quality', parseInt, 60 )
    .option( '--no-compress', "do not compress clusters" )
    .option( '--main <page-title>', 'title of the "home" page' )
    .option( '--no-zimlib4-fix', 'no workaround for zimlib v4.0.4' )
    // zimwriterfs "Mandatory" arguments:
    .option( '-w, --welcome <page>', 'path of default/main HTML page. The path must be relative to HTML_DIRECTORY', 'index.htm' )
    .option( '-f, --favicon <file>', 'path of ZIM file favicon. The path must be relative to HTML_DIRECTORY and the image a 48x48 PNG', 'favicon.png' )
    .option( '-l, --language <id>', 'language code of the content in ISO639-3', 'eng' )
    .option( '-t, --title <title>', 'title of the ZIM file', '' )
    .option( '-d, --description <text>', 'short description of the content', '' )
    .option( '-c, --creator  <text>', 'creator(s) of the content', '' )
    .option( '-p, --publisher  <text>', 'creator of the ZIM file itself', '' )
    // zimwriterfs "Optional" arguments:
    .option( '-v, --verbose', 'print processing details on STDOUT' )
    .option( '-q, --quiet', 'do not print on STDOUT' )
    .option( '-m, --minChunkSize <size>', 'number of bytes per ZIM cluster (default: 2048)', parseInt, 2048 )
    .option( '-x, --inflateHtml', 'try to inflate HTML files before packing (*.html, *.htm, ...)' )
    .option( '-u, --uniqueNamespace', 'put everything in the same namespace "A". Might be necessary to avoid problems with dynamic/javascript data loading' )
    .option( '-r, --redirects <path>', 'path to the CSV file with the list of redirects (url, title, target_url tab separated)', '' )
    // Not implemented
    //~ .option( '-i, --withFullTextIndex', 'index the content and add it to the ZIM' )
    .parse( osProcess.argv )

    log( command )

    const args = command.args

    while ( args[ 0 ] == '' ) // if mwoffliner prepends with empty extra parameter(s)
        args.shift()

    srcPath = expandHomeDir( args[ 0 ])
    if ( args[ 1 ])
        outPath = expandHomeDir( args[ 1 ])
    else {
        var parsed = osPath.parse( srcPath )
        outPath = parsed.base + '.zim'
    }

    //~ if ( command.minChunkSize ) {
        //~ ClusterSizeThreshold = command.minChunkSize * 1024
    //~ }

    await core ()
    print( 'Done' )
}

main ()
;