var Utils = require("./util"),
    Headers = require("./headers"),
    Constants = Utils.Constants,
    Methods = require("./methods");

module.exports = function (/*Buffer*/input) {

    var _entryHeader = new Headers.EntryHeader(),
        _entryName = Buffer.alloc(0),
        _comment = Buffer.alloc(0),
        _isDirectory = false,
        uncompressedData = null,
        _extra = Buffer.alloc(0);

    function getCompressedDataFromZip() {
        if (!input || !Buffer.isBuffer(input)) {
            return Buffer.alloc(0);
        }
        _entryHeader.loadDataHeaderFromBinary(input);
        return input.slice(_entryHeader.realDataOffset, _entryHeader.realDataOffset + _entryHeader.compressedSize)
    }

    function crc32OK(data) {
        // if bit 3 (0x08) of the general-purpose flags field is set, then the CRC-32 and file sizes are not known when the header is written
        if ((_entryHeader.flags & 0x8) !== 0x8) {
           if (Utils.crc32(data) !== _entryHeader.dataHeader.crc) {
               return false;
           }
        } else {
            // @TODO: load and check data descriptor header
            // The fields in the local header are filled with zero, and the CRC-32 and size are appended in a 12-byte structure
            // (optionally preceded by a 4-byte signature) immediately after the compressed data:
        }
        return true;
    }

    function decompress(/*Boolean*/async, /*Function*/callback, /*String*/pass) {
        if(typeof callback === 'undefined' && typeof async === 'string') {
            pass=async;
            async=void 0;
        }
        if (_isDirectory) {
            if (async && callback) {
                callback(Buffer.alloc(0), Utils.Errors.DIRECTORY_CONTENT_ERROR); //si added error.
            }
            return Buffer.alloc(0);
        }

        var compressedData = getCompressedDataFromZip();

        if (compressedData.length === 0) {
            // File is empty, nothing to decompress.
            if (async && callback) callback(compressedData);
            return compressedData;
        }

        var data = Buffer.alloc(_entryHeader.size);

        switch (_entryHeader.method) {
            case Utils.Constants.STORED:
                compressedData.copy(data);
                if (!crc32OK(data)) {
                    if (async && callback) callback(data, Utils.Errors.BAD_CRC);//si added error
                    throw new Error(Utils.Errors.BAD_CRC);
                } else {//si added otherwise did not seem to return data.
                    if (async && callback) callback(data);
                    return data;
                }
            case Utils.Constants.DEFLATED:
                var inflater = new Methods.Inflater(compressedData);
                if (!async) {
                    var result = inflater.inflate(data);
                    result.copy(data, 0);
                    if (!crc32OK(data)) {
                        throw new Error(Utils.Errors.BAD_CRC + " " + _entryName.toString());
                    }
                    return data;
                } else {
                    inflater.inflateAsync(function(result) {
                        result.copy(data, 0);
                        if (!crc32OK(data)) {
                            if (callback) callback(data, Utils.Errors.BAD_CRC); //si added error
                        } else { //si added otherwise did not seem to return data.
                            if (callback) callback(data);
                        }
                    })
                }
                break;
            default:
                if (async && callback) callback(Buffer.alloc(0), Utils.Errors.UNKNOWN_METHOD);
                throw new Error(Utils.Errors.UNKNOWN_METHOD);
        }
    }

    function compress(/*Boolean*/async, /*Function*/callback) {
        if ((!uncompressedData || !uncompressedData.length) && Buffer.isBuffer(input)) {
            // no data set or the data wasn't changed to require recompression
            if (async && callback) callback(getCompressedDataFromZip());
            return getCompressedDataFromZip();
        }

        if (uncompressedData.length && !_isDirectory) {
            var compressedData;
            // Local file header
            switch (_entryHeader.method) {
                case Utils.Constants.STORED:
                    _entryHeader.compressedSize = _entryHeader.size;

                    compressedData = Buffer.alloc(uncompressedData.length);
                    uncompressedData.copy(compressedData);

                    if (async && callback) callback(compressedData);
                    return compressedData;
                default:
                case Utils.Constants.DEFLATED:

                    var deflater = new Methods.Deflater(uncompressedData);
                    if (!async) {
                        var deflated = deflater.deflate();
                        _entryHeader.compressedSize = deflated.length;
                        return deflated;
                    } else {
                        deflater.deflateAsync(function(data) {
                            compressedData = Buffer.alloc(data.length);
                            _entryHeader.compressedSize = data.length;
                            data.copy(compressedData);
                            callback && callback(compressedData);
                        })
                    }
                    deflater = null;
                    break;
            }
        } else {
            if (async && callback) {
                callback(Buffer.alloc(0));
            } else {
                return Buffer.alloc(0);
            }
        }
    }

    function readUInt64LE(buffer, offset) {
        return (buffer.readUInt32LE(offset + 4) << 4) + buffer.readUInt32LE(offset);
    }

    function parseExtra(data) {
        var offset = 0;
        var signature, size, part;
        while(offset<data.length) {
            signature = data.readUInt16LE(offset);
            offset += 2;
            size = data.readUInt16LE(offset);
            offset += 2;
            part = data.slice(offset, offset+size);
            offset += size;
            if(Constants.ID_ZIP64 === signature) {
                parseZip64ExtendedInformation(part);
            }
        }
    }

    //Override header field values with values from the ZIP64 extra field
    function parseZip64ExtendedInformation(data) {
        var size, compressedSize, offset, diskNumStart;

        if(data.length >= Constants.EF_ZIP64_SCOMP) {
            size = readUInt64LE(data, Constants.EF_ZIP64_SUNCOMP);
            if(_entryHeader.size === Constants.EF_ZIP64_OR_32) {
                _entryHeader.size = size;
            }
        }
        if(data.length >= Constants.EF_ZIP64_RHO) {
            compressedSize = readUInt64LE(data, Constants.EF_ZIP64_SCOMP);
            if(_entryHeader.compressedSize === Constants.EF_ZIP64_OR_32) {
                _entryHeader.compressedSize = compressedSize;
            }
        }
        if(data.length >= Constants.EF_ZIP64_DSN) {
            offset = readUInt64LE(data, Constants.EF_ZIP64_RHO);
            if(_entryHeader.offset === Constants.EF_ZIP64_OR_32) {
                _entryHeader.offset = offset;
            }
        }
        if(data.length >= Constants.EF_ZIP64_DSN+4) {
            diskNumStart = data.readUInt32LE(Constants.EF_ZIP64_DSN);
            if(_entryHeader.diskNumStart === Constants.EF_ZIP64_OR_16) {
                _entryHeader.diskNumStart = diskNumStart;
            }
        }
    }


    return {
        get entryName () { return _entryName.toString(); },
        get rawEntryName() { return _entryName; },
        set entryName (val) {
            _entryName = Utils.toBuffer(val);
            var lastChar = _entryName[_entryName.length - 1];
            _isDirectory = (lastChar === 47) || (lastChar === 92);
            _entryHeader.fileNameLength = _entryName.length;
        },

        get extra () { return _extra; },
        set extra (val) {
            _extra = val;
            _entryHeader.extraLength = val.length;
            parseExtra(val);
        },

        get comment () { return _comment.toString(); },
        set comment (val) {
            _comment = Utils.toBuffer(val);
            _entryHeader.commentLength = _comment.length;
        },

        get name () { var n = _entryName.toString(); return _isDirectory ? n.substr(n.length - 1).split("/").pop() : n.split("/").pop(); },
        get isDirectory () { return _isDirectory },

        getCompressedData : function() {
            return compress(false, null)
        },

        getCompressedDataAsync : function(/*Function*/callback) {
            compress(true, callback)
        },

        setData : function(value) {
            uncompressedData = Utils.toBuffer(value);
            if (!_isDirectory && uncompressedData.length) {
                _entryHeader.size = uncompressedData.length;
                _entryHeader.method = Utils.Constants.DEFLATED;
                _entryHeader.crc = Utils.crc32(value);
                _entryHeader.changed = true;
            } else { // folders and blank files should be stored
                _entryHeader.method = Utils.Constants.STORED;
            }
        },

        getData : function(pass) {
            if (_entryHeader.changed) {
				return uncompressedData;
			} else {
				return decompress(false, null, pass);
            }
        },

        getDataAsync : function(/*Function*/callback, pass) {
			if (_entryHeader.changed) {
				callback(uncompressedData)
			} else {
				decompress(true, callback, pass)
            }
        },

        set attr(attr) { _entryHeader.attr = attr; },
        get attr() { return _entryHeader.attr; },

        set header(/*Buffer*/data) {
            _entryHeader.loadFromBinary(data);
        },

        get header() {
            return _entryHeader;
        },

        packHeader : function() {
            var header = _entryHeader.entryHeaderToBinary();
            // add
            _entryName.copy(header, Utils.Constants.CENHDR);
            if (_entryHeader.extraLength) {
                _extra.copy(header, Utils.Constants.CENHDR + _entryName.length)
            }
            if (_entryHeader.commentLength) {
                _comment.copy(header, Utils.Constants.CENHDR + _entryName.length + _entryHeader.extraLength, _comment.length);
            }
            return header;
        },

        toString : function() {
            return '{\n' +
                '\t"entryName" : "' + _entryName.toString() + "\",\n" +
                '\t"name" : "' + (_isDirectory ? _entryName.toString().replace(/\/$/, '').split("/").pop() : _entryName.toString().split("/").pop()) + "\",\n" +
                '\t"comment" : "' + _comment.toString() + "\",\n" +
                '\t"isDirectory" : ' + _isDirectory + ",\n" +
                '\t"header" : ' + _entryHeader.toString().replace(/\t/mg, "\t\t").replace(/}/mg, "\t}")  + ",\n" +
                '\t"compressedData" : <' + (input && input.length  + " bytes buffer" || "null") + ">\n" +
                '\t"data" : <' + (uncompressedData && uncompressedData.length  + " bytes buffer" || "null") + ">\n" +
                '}';
        }
    }
};