/* jslint node: true */
'use strict';

//  ENiGMA½
const Config            = require('./config.js').get;
const stringFormat      = require('./string_format.js');
const Errors            = require('./enig_error.js').Errors;
const resolveMimeType   = require('./mime_util.js').resolveMimeType;
const Events            = require('./events.js');

//  base/modules
const fs        = require('graceful-fs');
const _         = require('lodash');
const pty       = require('node-pty');
const paths     = require('path');

let archiveUtil;

class Archiver {
    constructor(config) {
        this.compress   = config.compress;
        this.decompress = config.decompress;
        this.list       = config.list;
        this.extract    = config.extract;
    }

    ok() {
        return this.canCompress() && this.canDecompress();
    }

    can(what) {
        if(!_.has(this, [ what, 'cmd' ]) || !_.has(this, [ what, 'args' ])) {
            return false;
        }

        return _.isString(this[what].cmd) && Array.isArray(this[what].args) && this[what].args.length > 0;
    }

    canCompress() { return this.can('compress'); }
    canDecompress() { return this.can('decompress'); }
    canList() { return this.can('list'); }  //  :TODO: validate entryMatch
    canExtract() { return this.can('extract'); }
}

module.exports = class ArchiveUtil {

    constructor() {
        this.archivers = {};
        this.longestSignature = 0;
    }

    //  singleton access
    static getInstance(hotReload = true) {
        if(!archiveUtil) {
            archiveUtil = new ArchiveUtil();
            archiveUtil.init(hotReload);
        }
        return archiveUtil;
    }

    init(hotReload = true) {
        this.reloadConfig();
        if(hotReload) {
            Events.on(Events.getSystemEvents().ConfigChanged, () => {
                this.reloadConfig();
            });
        }
    }

    reloadConfig() {
        const config = Config();
        if(_.has(config, 'archives.archivers')) {
            Object.keys(config.archives.archivers).forEach(archKey => {

                const archConfig    = config.archives.archivers[archKey];
                const archiver      = new Archiver(archConfig);

                if(!archiver.ok()) {
                    //  :TODO: Log warning - bad archiver/config
                }

                this.archivers[archKey] = archiver;
            });
        }

        if(_.isObject(config.fileTypes)) {
            const updateSig = (ft) => {
                ft.sig      = Buffer.from(ft.sig, 'hex');
                ft.offset   = ft.offset || 0;

                //  :TODO: this is broken: sig is NOT this long, it's sig.length long; offset needs to allow for -negative values as well
                const sigLen = ft.offset + ft.sig.length;
                if(sigLen > this.longestSignature) {
                    this.longestSignature = sigLen;
                }
            };

            Object.keys(config.fileTypes).forEach(mimeType => {
                const fileType = config.fileTypes[mimeType];
                if(Array.isArray(fileType)) {
                    fileType.forEach(ft => {
                        if(ft.sig) {
                            updateSig(ft);
                        }
                    });
                } else if(fileType.sig) {
                    updateSig(fileType);
                }
            });
        }
    }

    getArchiver(mimeTypeOrExtension, justExtention) {
        const mimeType = resolveMimeType(mimeTypeOrExtension);

        if(!mimeType) { //  lookup returns false on failure
            return;
        }

        const config = Config();
        let fileType = _.get(config, [ 'fileTypes', mimeType ] );

        if(Array.isArray(fileType)) {
            if(!justExtention) {
                //  need extention for lookup; ambiguous as-is :(
                return;
            }
            //  further refine by extention
            fileType = fileType.find(ft => justExtention === ft.ext);
        }

        if(!_.isObject(fileType)) {
            return;
        }

        if(fileType.archiveHandler) {
            return _.get( config, [ 'archives', 'archivers', fileType.archiveHandler ] );
        }
    }

    haveArchiver(archType) {
        return this.getArchiver(archType) ? true : false;
    }

    //  :TODO: implement me:
    /*
    detectTypeWithBuf(buf, cb) {
    }
    */

    detectType(path, cb) {
        const closeFile = (fd) => {
            fs.close(fd, () => { /* sadface */ });
        };

        fs.open(path, 'r', (err, fd) => {
            if(err) {
                return cb(err);
            }

            const buf = Buffer.alloc(this.longestSignature);
            fs.read(fd, buf, 0, buf.length, 0, (err, bytesRead) => {
                if(err) {
                    closeFile(fd);
                    return cb(err);
                }

                const archFormat = _.findKey(Config().fileTypes, fileTypeInfo => {
                    const fileTypeInfos = Array.isArray(fileTypeInfo) ? fileTypeInfo : [ fileTypeInfo ];
                    return fileTypeInfos.find(fti => {
                        if(!fti.sig || !fti.archiveHandler) {
                            return false;
                        }

                        const lenNeeded = fti.offset + fti.sig.length;

                        if(bytesRead < lenNeeded) {
                            return false;
                        }

                        const comp = buf.slice(fti.offset, fti.offset + fti.sig.length);
                        return (fti.sig.equals(comp));
                    });
                });

                closeFile(fd);
                return cb(archFormat ? null : Errors.General('Unknown type'), archFormat);
            });
        });
    }

    spawnHandler(proc, action, cb) {
        //  pty.js doesn't currently give us a error when things fail,
        //  so we have this horrible, horrible hack:
        let err;
        proc.once('data', d => {
            if(_.isString(d) && d.startsWith('execvp(3) failed.')) {
                err = Errors.ExternalProcess(`${action} failed: ${d.trim()}`);
            }
        });

        proc.once('exit', exitCode => {
            return cb(exitCode ? Errors.ExternalProcess(`${action} failed with exit code: ${exitCode}`) : err);
        });
    }

    compressTo(archType, archivePath, files, workDir, cb) {
        const archiver = this.getArchiver(archType, paths.extname(archivePath));

        if(!archiver) {
            return cb(Errors.Invalid(`Unknown archive type: ${archType}`));
        }

        if (!cb && _.isFunction(workDir)) {
            cb = workDir;
            workDir = null;
        }

        const fmtObj = {
            archivePath : archivePath,
            fileList    : files.join(' '),  //  :TODO: probably need same hack as extractTo here!
        };

        //  :TODO: DRY with extractTo()
        const args = archiver.compress.args.map( arg => {
            return '{fileList}' === arg ? arg : stringFormat(arg, fmtObj);
        });

        const fileListPos = args.indexOf('{fileList}');
        if(fileListPos > -1) {
            //  replace {fileList} with 0:n sep file list arguments
            args.splice.apply(args, [fileListPos, 1].concat(files));
        }

        let proc;
        try {
            proc = pty.spawn(archiver.compress.cmd, args, this.getPtyOpts(workDir));
        } catch(e) {
            return cb(Errors.ExternalProcess(
                `Error spawning archiver process "${archiver.compress.cmd}" with args "${args.join(' ')}": ${e.message}`)
            );
        }

        return this.spawnHandler(proc, 'Compression', cb);
    }

    extractTo(archivePath, extractPath, archType, fileList, cb) {
        let haveFileList;

        if(!cb && _.isFunction(fileList)) {
            cb = fileList;
            fileList = [];
            haveFileList = false;
        } else {
            haveFileList = true;
        }

        const archiver = this.getArchiver(archType, paths.extname(archivePath));

        if(!archiver) {
            return cb(Errors.Invalid(`Unknown archive type: ${archType}`));
        }

        const fmtObj = {
            archivePath     : archivePath,
            extractPath     : extractPath,
        };

        let action = haveFileList ? 'extract' : 'decompress';
        if('extract' === action && !_.isObject(archiver[action])) {
            //  we're forced to do a full decompress
            action = 'decompress';
            haveFileList = false;
        }

        //  we need to treat {fileList} special in that it should be broken up to 0:n args
        const args = archiver[action].args.map( arg => {
            return '{fileList}' === arg ? arg : stringFormat(arg, fmtObj);
        });

        const fileListPos = args.indexOf('{fileList}');
        if(fileListPos > -1) {
            //  replace {fileList} with 0:n sep file list arguments
            args.splice.apply(args, [fileListPos, 1].concat(fileList));
        }

        let proc;
        try {
            proc = pty.spawn(archiver[action].cmd, args, this.getPtyOpts(extractPath));
        } catch(e) {
            return cb(Errors.ExternalProcess(
                `Error spawning archiver process "${archiver[action].cmd}" with args "${args.join(' ')}": ${e.message}`)
            );
        }

        return this.spawnHandler(proc, (haveFileList ? 'Extraction' : 'Decompression'), cb);
    }

    listEntries(archivePath, archType, cb) {
        const archiver = this.getArchiver(archType, paths.extname(archivePath));

        if(!archiver) {
            return cb(Errors.Invalid(`Unknown archive type: ${archType}`));
        }

        const fmtObj = {
            archivePath     : archivePath,
        };

        const args  = archiver.list.args.map( arg => stringFormat(arg, fmtObj) );

        let proc;
        try {
            proc = pty.spawn(archiver.list.cmd, args, this.getPtyOpts());
        } catch(e) {
            return cb(Errors.ExternalProcess(
                `Error spawning archiver process "${archiver.list.cmd}" with args "${args.join(' ')}": ${e.message}`)
            );
        }

        let output = '';
        proc.on('data', data => {
            //  :TODO: hack for: execvp(3) failed.: No such file or directory

            output += data;
        });

        proc.once('exit', exitCode => {
            if(exitCode) {
                return cb(Errors.ExternalProcess(`List failed with exit code: ${exitCode}`));
            }

            const entryGroupOrder = archiver.list.entryGroupOrder || { byteSize : 1, fileName : 2 };

            const entries = [];
            const entryMatchRe = new RegExp(archiver.list.entryMatch, 'gm');
            let m;
            while((m = entryMatchRe.exec(output))) {
                entries.push({
                    byteSize    : parseInt(m[entryGroupOrder.byteSize]),
                    fileName    : m[entryGroupOrder.fileName].trim(),
                });
            }

            return cb(null, entries);
        });
    }

    getPtyOpts(cwd) {
        const opts = {
            name    : 'enigma-archiver',
            cols    : 80,
            rows    : 24,
            env     : process.env,
        };
        if(cwd) {
            opts.cwd = cwd;
        }
        //  :TODO: set cwd to supplied temp path if not sepcific extract
        return opts;
    }
};