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

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

//	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() {
		if(!archiveUtil) {
			archiveUtil = new ArchiveUtil();
			archiveUtil.init();
		}
		return archiveUtil;
	}

	init() {
		//
		//	Load configuration
		//
		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;
		}

		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) {
		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) {
					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));
					});
				});

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

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

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

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

		let proc;
		try {
			proc = pty.spawn(archiver.compress.cmd, args, this.getPtyOpts());
		} catch(e) {
			return cb(e);
		}

		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(e);
		}

		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(e);
		}

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