/**
 * unrar.js
 *
 * Copyright(c) 2011 Google Inc.
 * Copyright(c) 2011 antimatter15
 *
 * Reference Documentation:
 *
 * http://kthoom.googlecode.com/hg/docs/unrar.html
 */
/* global bitjs, importScripts */

// This file expects to be invoked as a Worker (see onmessage below).
importScripts("io.js");
importScripts("archive.js");

// Progress variables.
var currentFilename = "";
var currentFileNumber = 0;
var currentBytesUnarchivedInFile = 0;
var currentBytesUnarchived = 0;
var totalUncompressedBytesInArchive = 0;
var totalFilesInArchive = 0;

// Helper functions.
var info = function(str) {
    postMessage(new bitjs.archive.UnarchiveInfoEvent(str));
};
var err = function(str) {
    postMessage(new bitjs.archive.UnarchiveErrorEvent(str));
};
var postProgress = function() {
    postMessage(new bitjs.archive.UnarchiveProgressEvent(
        currentFilename,
        currentFileNumber,
        currentBytesUnarchivedInFile,
        currentBytesUnarchived,
        totalUncompressedBytesInArchive,
        totalFilesInArchive));
};

// shows a byte value as its hex representation
var nibble = "0123456789ABCDEF";
var byteValueToHexString = function(num) {
    return nibble[num >> 4] + nibble[num & 0xF];
};
var twoByteValueToHexString = function(num) {
    return nibble[(num >> 12) & 0xF] + nibble[(num >> 8) & 0xF] + nibble[(num >> 4) & 0xF] + nibble[num & 0xF];
};


// Volume Types
// MARK_HEAD      = 0x72;
var MAIN_HEAD      = 0x73,
    FILE_HEAD      = 0x74,
    // COMM_HEAD      = 0x75,
    // AV_HEAD        = 0x76,
    // SUB_HEAD       = 0x77,
    // PROTECT_HEAD   = 0x78,
    // SIGN_HEAD      = 0x79,
    // NEWSUB_HEAD    = 0x7a,
    ENDARC_HEAD    = 0x7b;

// bstream is a bit stream
var RarVolumeHeader = function(bstream) {

    var headPos = bstream.bytePtr;
    // byte 1,2
    info("Rar Volume Header @" + bstream.bytePtr);

    this.crc = bstream.readBits(16);
    info("  crc=" + this.crc);

    // byte 3
    this.headType = bstream.readBits(8);
    info("  headType=" + this.headType);

    // Get flags
    // bytes 4,5
    this.flags = {};
    this.flags.value = bstream.peekBits(16);
  
    info("  flags=" + twoByteValueToHexString(this.flags.value));
    switch (this.headType) {
        case MAIN_HEAD:
            this.flags.MHD_VOLUME = !!bstream.readBits(1);
            this.flags.MHD_COMMENT = !!bstream.readBits(1);
            this.flags.MHD_LOCK = !!bstream.readBits(1);
            this.flags.MHD_SOLID = !!bstream.readBits(1);
            this.flags.MHD_PACK_COMMENT = !!bstream.readBits(1);
            this.flags.MHD_NEWNUMBERING = this.flags.MHD_PACK_COMMENT;
            this.flags.MHD_AV = !!bstream.readBits(1);
            this.flags.MHD_PROTECT = !!bstream.readBits(1);
            this.flags.MHD_PASSWORD = !!bstream.readBits(1);
            this.flags.MHD_FIRSTVOLUME = !!bstream.readBits(1);
            this.flags.MHD_ENCRYPTVER = !!bstream.readBits(1);
            bstream.readBits(6); // unused
            break;
        case FILE_HEAD:
            this.flags.LHD_SPLIT_BEFORE = !!bstream.readBits(1); // 0x0001
            this.flags.LHD_SPLIT_AFTER = !!bstream.readBits(1); // 0x0002
            this.flags.LHD_PASSWORD = !!bstream.readBits(1); // 0x0004
            this.flags.LHD_COMMENT = !!bstream.readBits(1); // 0x0008
            this.flags.LHD_SOLID = !!bstream.readBits(1); // 0x0010
            bstream.readBits(3); // unused
            this.flags.LHD_LARGE = !!bstream.readBits(1); // 0x0100
            this.flags.LHD_UNICODE = !!bstream.readBits(1); // 0x0200
            this.flags.LHD_SALT = !!bstream.readBits(1); // 0x0400
            this.flags.LHD_VERSION = !!bstream.readBits(1); // 0x0800
            this.flags.LHD_EXTTIME = !!bstream.readBits(1); // 0x1000
            this.flags.LHD_EXTFLAGS = !!bstream.readBits(1); // 0x2000
            bstream.readBits(2); // unused
            info("  LHD_SPLIT_BEFORE = " + this.flags.LHD_SPLIT_BEFORE);
            break;
        default:
            bstream.readBits(16);
    }
  
    // byte 6,7
    this.headSize = bstream.readBits(16);
    info("  headSize=" + this.headSize);
    switch (this.headType) {
        case MAIN_HEAD:
            this.highPosAv = bstream.readBits(16);
            this.posAv = bstream.readBits(32);
            if (this.flags.MHD_ENCRYPTVER) {
                this.encryptVer = bstream.readBits(8);
            }
            info("Found MAIN_HEAD with highPosAv=" + this.highPosAv + ", posAv=" + this.posAv);
            break;
        case FILE_HEAD:
            this.packSize = bstream.readBits(32);
            this.unpackedSize = bstream.readBits(32);
            this.hostOS = bstream.readBits(8);
            this.fileCRC = bstream.readBits(32);
            this.fileTime = bstream.readBits(32);
            this.unpVer = bstream.readBits(8);
            this.method = bstream.readBits(8);
            this.nameSize = bstream.readBits(16);
            this.fileAttr = bstream.readBits(32);

            if (this.flags.LHD_LARGE) {
                info("Warning: Reading in LHD_LARGE 64-bit size values");
                this.HighPackSize = bstream.readBits(32);
                this.HighUnpSize = bstream.readBits(32);
            } else {
                this.HighPackSize = 0;
                this.HighUnpSize = 0;
                if (this.unpackedSize === 0xffffffff) {
                    this.HighUnpSize = 0x7fffffff;
                    this.unpackedSize = 0xffffffff;
                }
            }
            this.fullPackSize = 0;
            this.fullUnpackSize = 0;
            this.fullPackSize |= this.HighPackSize;
            this.fullPackSize <<= 32;
            this.fullPackSize |= this.packSize;

            // read in filename

            this.filename = bstream.readBytes(this.nameSize);
            var _s = ""
            for (var _i = 0; _i < this.filename.length ; _i++) {
                _s += String.fromCharCode(this.filename[_i]);
            }

            this.filename = _s;

            if (this.flags.LHD_SALT) {
                info("Warning: Reading in 64-bit salt value");
                this.salt = bstream.readBits(64); // 8 bytes
            }

            if (this.flags.LHD_EXTTIME) {
                // 16-bit flags
                var extTimeFlags = bstream.readBits(16);

                // this is adapted straight out of arcread.cpp, Archive::ReadHeader()
                for (var I = 0; I < 4; ++I) {
                    var rmode = extTimeFlags >> ((3 - I) * 4);
                    if ((rmode & 8) === 0) {
                        continue;
                    }
                    if (I !== 0) {
                        bstream.readBits(16);
                    }
                    var count = (rmode & 3);
                    for (var J = 0; J < count; ++J) {
                        bstream.readBits(8);
                    }
                }
            }

            if (this.flags.LHD_COMMENT) {
                info("Found a LHD_COMMENT");
            }


            while (headPos + this.headSize > bstream.bytePtr) bstream.readBits(1);

            info("Found FILE_HEAD with packSize=" + this.packSize + ", unpackedSize= " + this.unpackedSize + ", hostOS=" + this.hostOS + ", unpVer=" + this.unpVer + ", method=" + this.method + ", filename=" + this.filename);

            break;
        default:
            info("Found a header of type 0x" + byteValueToHexString(this.headType));
            // skip the rest of the header bytes (for now)
            bstream.readBytes( this.headSize - 7 );
            break;
    }
};

//var BLOCK_LZ  = 0;

var rLDecode = [0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, 24, 28, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224], 
    rLBits = [0, 0, 0, 0, 0, 0, 0, 0, 1,  1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4,  4,  5,  5,  5,  5],
    rDBitLengthCounts = [4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 14, 0, 12],
    rSDDecode = [0, 4, 8, 16, 32, 64, 128, 192],
    rSDBits = [2, 2, 3, 4, 5, 6,  6,  6];
  
var rDDecode = [0, 1, 2, 3, 4, 6, 8, 12, 16, 24, 32,
    48, 64, 96, 128, 192, 256, 384, 512, 768, 1024, 1536, 2048, 3072,
    4096, 6144, 8192, 12288, 16384, 24576, 32768, 49152, 65536, 98304,
    131072, 196608, 262144, 327680, 393216, 458752, 524288, 589824,
    655360, 720896, 786432, 851968, 917504, 983040];

var rDBits = [0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5,
    5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14,
    15, 15, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16];

var rLowDistRepCount = 16;

var rNC = 299,
    rDC = 60,
    rLDC = 17,
    rRC = 28,
    rBC = 20,
    rHuffTableSize = (rNC + rDC + rRC + rLDC);

//var UnpBlockType = BLOCK_LZ;
var UnpOldTable = new Array(rHuffTableSize);

var BD = { //bitdecode
    DecodeLen: new Array(16),
    DecodePos: new Array(16),
    DecodeNum: new Array(rBC)
};
var LD = { //litdecode
    DecodeLen: new Array(16),
    DecodePos: new Array(16),
    DecodeNum: new Array(rNC)
};
var DD = { //distdecode
    DecodeLen: new Array(16),
    DecodePos: new Array(16),
    DecodeNum: new Array(rDC)
};
var LDD = { //low dist decode
    DecodeLen: new Array(16),
    DecodePos: new Array(16),
    DecodeNum: new Array(rLDC)
};
var RD = { //rep decode
    DecodeLen: new Array(16),
    DecodePos: new Array(16),
    DecodeNum: new Array(rRC)
};

var rBuffer;

// read in Huffman tables for RAR
function RarReadTables(bstream) {
    var BitLength = new Array(rBC),
        Table = new Array(rHuffTableSize);
    var i;
    // before we start anything we need to get byte-aligned
    bstream.readBits( (8 - bstream.bitPtr) & 0x7 );
  
    if (bstream.readBits(1)) {
        info("Error!  PPM not implemented yet");
        return;
    }
  
    if (!bstream.readBits(1)) { //discard old table
        for (i = UnpOldTable.length; i--;) UnpOldTable[i] = 0;
    }

    // read in bit lengths
    for (var I = 0; I < rBC; ++I) {

        var Length = bstream.readBits(4);
        if (Length === 15) {
            var ZeroCount = bstream.readBits(4);
            if (ZeroCount === 0) {
                BitLength[I] = 15;
            } else {
                ZeroCount += 2;
                while (ZeroCount-- > 0 && I < rBC) {
                    BitLength[I++] = 0;
                }
                --I;
            }
        } else {
            BitLength[I] = Length;
        }
    }

    // now all 20 bit lengths are obtained, we construct the Huffman Table:

    rarMakeDecodeTables(BitLength, 0, BD, rBC);
  
    var TableSize = rHuffTableSize;
    //console.log(DecodeLen, DecodePos, DecodeNum);
    for (i = 0; i < TableSize;) {
        var N;
        var num = RarDecodeNumber(bstream, BD);
        if (num < 16) {
            Table[i] = (num + UnpOldTable[i]) & 0xf;
            i++;
        } else if (num < 18) {
            N = (num === 16) ? (bstream.readBits(3) + 3) : (bstream.readBits(7) + 11);

            while (N-- > 0 && i < TableSize) {
                Table[i] = Table[i - 1];
                i++;
            }
        } else {
            N = (num === 18) ? (bstream.readBits(3) + 3) : (bstream.readBits(7) + 11);

            while (N-- > 0 && i < TableSize) {
                Table[i++] = 0;
            }
        }
    }
  
    rarMakeDecodeTables(Table, 0, LD, rNC);
    rarMakeDecodeTables(Table, rNC, DD, rDC);
    rarMakeDecodeTables(Table, rNC + rDC, LDD, rLDC);
    rarMakeDecodeTables(Table, rNC + rDC + rLDC, RD, rRC);
  
    for (i = UnpOldTable.length; i--;) {
        UnpOldTable[i] = Table[i];
    }
    return true;
}


function RarDecodeNumber(bstream, dec) {
    var DecodeLen = dec.DecodeLen, DecodePos = dec.DecodePos, DecodeNum = dec.DecodeNum;
    var bitField = bstream.getBits() & 0xfffe;
    //some sort of rolled out binary search
    var bits = ((bitField < DecodeLen[8]) ?
        ((bitField < DecodeLen[4]) ?
            ((bitField < DecodeLen[2]) ?
                ((bitField < DecodeLen[1]) ? 1 : 2)
                : ((bitField < DecodeLen[3]) ? 3 : 4))
            : (bitField < DecodeLen[6]) ?
                ((bitField < DecodeLen[5]) ? 5 : 6)
                : ((bitField < DecodeLen[7]) ? 7 : 8))
        : ((bitField < DecodeLen[12]) ?
            ((bitField < DecodeLen[10]) ?
                ((bitField < DecodeLen[9]) ? 9 : 10)
                : ((bitField < DecodeLen[11]) ? 11 : 12))
            : (bitField < DecodeLen[14]) ?
                ((bitField < DecodeLen[13]) ? 13 : 14)
                : 15));
    bstream.readBits(bits);
    var N = DecodePos[bits] + ((bitField - DecodeLen[bits -1]) >>> (16 - bits));
  
    return DecodeNum[N];
}


function rarMakeDecodeTables(BitLength, offset, dec, size) {
    var DecodeLen = dec.DecodeLen, DecodePos = dec.DecodePos, DecodeNum = dec.DecodeNum;
    var LenCount = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
        TmpPos = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
        N = 0, M = 0;
    for (var i = DecodeNum.length; i--;) DecodeNum[i] = 0;
    for (var i = 0; i < size; i++) {
        LenCount[BitLength[i + offset] & 0xF]++;
    }
    LenCount[0] = 0;
    TmpPos[0] = 0;
    DecodePos[0] = 0;
    DecodeLen[0] = 0;
  
    for (var I = 1; I < 16; ++I) {
        N = 2 * (N + LenCount[I]);
        M = (N << (15-I));
        if (M > 0xFFFF)
            M = 0xFFFF;
        DecodeLen[I] = M;
        DecodePos[I] = DecodePos[I-1] + LenCount[I-1];
        TmpPos[I] = DecodePos[I];
    }
    for (I = 0; I < size; ++I) {
        if (BitLength[I + offset] != 0) {
            DecodeNum[ TmpPos[ BitLength[offset + I] & 0xF ]++] = I;
        }
    }
}

// TODO: implement
function Unpack15(bstream, Solid) {
    info("ERROR!  RAR 1.5 compression not supported");
}

function Unpack20(bstream, Solid) {
    var destUnpSize = rBuffer.data.length;
    var oldDistPtr = 0;
  
    RarReadTables20(bstream);
    while (destUnpSize > rBuffer.ptr) {
        var num = RarDecodeNumber(bstream, LD);
        if (num < 256) {
            rBuffer.insertByte(num);
            continue;
        }
        if (num > 269) {
            var Length = rLDecode[num -= 270] + 3;
            if ((Bits = rLBits[num]) > 0) {
                Length += bstream.readBits(Bits);
            }
            var DistNumber = RarDecodeNumber(bstream, DD);
            var Distance = rDDecode[DistNumber] + 1;
            if ((Bits = rDBits[DistNumber]) > 0) {
                Distance += bstream.readBits(Bits);
            }
            if (Distance >= 0x2000) {
                Length++;
                if(Distance >= 0x40000) Length++;
            }
            lastLength = Length;
            lastDist = rOldDist[oldDistPtr++ & 3] = Distance;
            RarCopyString(Length, Distance);
            continue;
        }
        if (num === 269) {
            RarReadTables20(bstream);

            RarUpdateProgress()

            continue;
        }
        if (num === 256) {
            lastDist = rOldDist[oldDistPtr++ & 3] = lastDist;
            RarCopyString(lastLength, lastDist);
            continue;
        }
        if (num < 261) {
            var Distance = rOldDist[(oldDistPtr - (num - 256)) & 3];
            var LengthNumber = RarDecodeNumber(bstream, RD);
            var Length = rLDecode[LengthNumber] +2;
            if ((Bits = rLBits[LengthNumber]) > 0) {
                Length += bstream.readBits(Bits);
            }
            if (Distance >= 0x101) {
                Length++;
                if (Distance >= 0x2000) {
                    Length++
                    if (Distance >= 0x40000) Length++;
                }
            }
            lastLength = Length;
            lastDist = rOldDist[oldDistPtr++ & 3] = Distance;
            RarCopyString(Length, Distance);
            continue;
        }
        if (num < 270) {
            var Distance = rSDDecode[num -= 261] + 1;
            if ((Bits = rSDBits[num]) > 0) {
                Distance += bstream.readBits(Bits);
            }
            lastLength = 2;
            lastDist = rOldDist[oldDistPtr++ & 3] = Distance;
            RarCopyString(2, Distance);
            continue;
        }
    }
    RarUpdateProgress()
}

function RarUpdateProgress() {
    var change = rBuffer.ptr - currentBytesUnarchivedInFile;
    currentBytesUnarchivedInFile = rBuffer.ptr;
    currentBytesUnarchived += change;
    postProgress();
}


var rNC20 = 298,
    rDC20 = 48,
    rRC20 = 28,
    rBC20 = 19,
    rMC20 = 257;

var UnpOldTable20 = new Array(rMC20 * 4);

function RarReadTables20(bstream) {
    var BitLength = new Array(rBC20);
    var Table = new Array(rMC20 * 4);
    var TableSize, N, I;
    var AudioBlock = bstream.readBits(1);
    if (!bstream.readBits(1))
        for (var i = UnpOldTable20.length; i--;) UnpOldTable20[i] = 0;
    TableSize = rNC20 + rDC20 + rRC20;
    for (var I = 0; I < rBC20; I++)
    BitLength[I] = bstream.readBits(4);
    rarMakeDecodeTables(BitLength, 0, BD, rBC20);
    I = 0;
    while (I < TableSize) {
        var num = RarDecodeNumber(bstream, BD);
        if (num < 16) {
          Table[I] = num + UnpOldTable20[I] & 0xf;
          I++;
        } else if(num === 16) {
            N = bstream.readBits(2) + 3;
            while (N-- > 0 && I < TableSize) {
                Table[I] = Table[I - 1];
                I++;
            }
        } else {
            if (num === 17) {
                N = bstream.readBits(3) + 3;
            } else {
                N = bstream.readBits(7) + 11;
            }
            while (N-- > 0 && I < TableSize) {
                Table[I++] = 0;
            }
        }
    }
    rarMakeDecodeTables(Table, 0, LD, rNC20);
    rarMakeDecodeTables(Table, rNC20, DD, rDC20);
    rarMakeDecodeTables(Table, rNC20 + rDC20, RD, rRC20);
    for (var i = UnpOldTable20.length; i--;) UnpOldTable20[i] = Table[i];
}

var lowDistRepCount = 0, prevLowDist = 0;

var rOldDist = [0,0,0,0];
var lastDist;
var lastLength;


function Unpack29(bstream, Solid) {
    // lazy initialize rDDecode and rDBits

    var DDecode = new Array(rDC);
    var DBits = new Array(rDC);

    var Dist=0,BitLength=0,Slot=0;

    for (var I = 0; I < rDBitLengthCounts.length; I++,BitLength++) {
        for (var J = 0; J < rDBitLengthCounts[I]; J++,Slot++,Dist+=(1<<BitLength)) {
            DDecode[Slot]=Dist;
            DBits[Slot]=BitLength;
        }
    }
  
    var Bits;
    //tablesRead = false;

    rOldDist = [0,0,0,0]

    lastDist = 0;
    lastLength = 0;

    for (var i = UnpOldTable.length; i--;) UnpOldTable[i] = 0;
    
    // read in Huffman tables
    RarReadTables(bstream);
 
    while (true) {
        var num = RarDecodeNumber(bstream, LD);
    
        if (num < 256) {
            rBuffer.insertByte(num);
            continue;
        }
        if (num >= 271) {
            var Length = rLDecode[num -= 271] + 3;
            if ((Bits = rLBits[num]) > 0) {
                Length += bstream.readBits(Bits);
            }
            var DistNumber = RarDecodeNumber(bstream, DD);
            var Distance = DDecode[DistNumber]+1;
            if ((Bits = DBits[DistNumber]) > 0) {
                if (DistNumber > 9) {
                    if (Bits > 4) {
                        Distance += ((bstream.getBits() >>> (20 - Bits)) << 4);
                        bstream.readBits(Bits - 4);
                        //todo: check this
                    }
                    if (lowDistRepCount > 0) {
                        lowDistRepCount--;
                        Distance += prevLowDist;
                    } else {
                        var LowDist = RarDecodeNumber(bstream, LDD);
                        if (LowDist === 16) {
                            lowDistRepCount = rLowDistRepCount - 1;
                            Distance += prevLowDist;
                        } else {
                            Distance += LowDist;
                            prevLowDist = LowDist;
                        }
                    }
                } else {
                    Distance += bstream.readBits(Bits);
                }
            }
            if (Distance >= 0x2000) {
                Length++;
                if (Distance >= 0x40000) {
                    Length++;
                }
            }
            RarInsertOldDist(Distance);
            RarInsertLastMatch(Length, Distance);
            RarCopyString(Length, Distance);
            continue;
        }
        if (num === 256) {
            if (!RarReadEndOfBlock(bstream)) break;
            continue;
        }
        if (num === 257) {
            //console.log("READVMCODE");
            if (!RarReadVMCode(bstream)) break;
                continue;
        }
        if (num === 258) {
            if (lastLength != 0) {
                RarCopyString(lastLength, lastDist);
            }
            continue;
        }
        if (num < 263) {
            var DistNum = num - 259;
            var Distance = rOldDist[DistNum];

            for (var I = DistNum; I > 0; I--) {
                rOldDist[I] = rOldDist[I-1];
            }
            rOldDist[0] = Distance;

            var LengthNumber = RarDecodeNumber(bstream, RD);
            var Length = rLDecode[LengthNumber] + 2;
            if ((Bits = rLBits[LengthNumber]) > 0) {
                Length += bstream.readBits(Bits);
            }
            RarInsertLastMatch(Length, Distance);
            RarCopyString(Length, Distance);
            continue;
        }
        if (num < 272) {
            var Distance = rSDDecode[num -= 263] + 1;
            if ((Bits = rSDBits[num]) > 0) {
                Distance += bstream.readBits(Bits);
            }
            RarInsertOldDist(Distance);
            RarInsertLastMatch(2, Distance);
            RarCopyString(2, Distance);
            continue;
        }
    }
    RarUpdateProgress()
}

function RarReadEndOfBlock(bstream) {
  
    RarUpdateProgress()

    var NewTable = false, NewFile = false;
    if (bstream.readBits(1)) {
        NewTable = true;
    } else {
        NewFile = true;
        NewTable = !!bstream.readBits(1);
    }
    //tablesRead = !NewTable;
    return !(NewFile || NewTable && !RarReadTables(bstream));
}


function RarReadVMCode(bstream) {
    var FirstByte = bstream.readBits(8);
    var Length = (FirstByte & 7) + 1;
    if (Length === 7) {
        Length = bstream.readBits(8) + 7;
    } else if(Length === 8) {
        Length = bstream.readBits(16);
    }
    var vmCode = [];
    for(var I = 0; I < Length; I++) {
        //do something here with cheking readbuf
        vmCode.push(bstream.readBits(8));
    }
    return RarAddVMCode(FirstByte, vmCode, Length);
}

function RarAddVMCode(firstByte, vmCode, length) {
    //console.log(vmCode);
    if (vmCode.length > 0) {
        info("Error! RarVM not supported yet!");
    }
    return true;
}

function RarInsertLastMatch(length, distance) {
    lastDist = distance;
    lastLength = length;
}

function RarInsertOldDist(distance) {
    rOldDist.splice(3,1);
    rOldDist.splice(0,0,distance);
}

//this is the real function, the other one is for debugging
function RarCopyString(length, distance) {
    var destPtr = rBuffer.ptr - distance;
    if(destPtr < 0){
        var l = rOldBuffers.length;
        while(destPtr < 0){
            destPtr = rOldBuffers[--l].data.length + destPtr;
        }
        //TODO: lets hope that it never needs to read beyond file boundaries
        while(length--) rBuffer.insertByte(rOldBuffers[l].data[destPtr++]);
    }
    if (length > distance) {
        while(length--) rBuffer.insertByte(rBuffer.data[destPtr++]);
    } else {
        rBuffer.insertBytes(rBuffer.data.subarray(destPtr, destPtr + length));
    }
}

var rOldBuffers = []
// v must be a valid RarVolume
function unpack(v) {

  // TODO: implement what happens when unpVer is < 15
    var Ver = v.header.unpVer <= 15 ? 15 : v.header.unpVer,
        Solid = v.header.LHD_SOLID,
        bstream = new bitjs.io.BitStream(v.fileData.buffer, true /* rtl */, v.fileData.byteOffset, v.fileData.byteLength );
  
    rBuffer = new bitjs.io.ByteBuffer(v.header.unpackedSize);

    info("Unpacking " + v.filename+" RAR v" + Ver);
    
    switch(Ver) {
        case 15: // rar 1.5 compression
            Unpack15(bstream, Solid);
            break;
        case 20: // rar 2.x compression
        case 26: // files larger than 2GB
            Unpack20(bstream, Solid);
            break;
        case 29: // rar 3.x compression
        case 36: // alternative hash
            Unpack29(bstream, Solid);
            break;
    } // switch(method)
  
    rOldBuffers.push(rBuffer);
    //TODO: clear these old buffers when there's over 4MB of history
    return rBuffer.data;
}

// bstream is a bit stream
var RarLocalFile = function(bstream) {
  
    this.header = new RarVolumeHeader(bstream);
    this.filename = this.header.filename;
  
    if (this.header.headType != FILE_HEAD && this.header.headType != ENDARC_HEAD) {
        this.isValid = false;
        info("Error! RAR Volume did not include a FILE_HEAD header ");
    } else {
        // read in the compressed data
        this.fileData = null;
        if (this.header.packSize > 0) {
            this.fileData = bstream.readBytes(this.header.packSize);
            this.isValid = true;
        }
    }
};

RarLocalFile.prototype.unrar = function() {

    if (!this.header.flags.LHD_SPLIT_BEFORE) {
        // unstore file
        if (this.header.method === 0x30) {
            info("Unstore " + this.filename);
            this.isValid = true;
      
            currentBytesUnarchivedInFile += this.fileData.length;
            currentBytesUnarchived += this.fileData.length;

            // Create a new buffer and copy it over.
            var len = this.header.packSize;
            var newBuffer = new bitjs.io.ByteBuffer(len);
            newBuffer.insertBytes(this.fileData);
            this.fileData = newBuffer.data;
        } else {
            this.isValid = true;
            this.fileData = unpack(this);
        }
    }
}

var unrar = function(arrayBuffer) {
    currentFilename = "";
    currentFileNumber = 0;
    currentBytesUnarchivedInFile = 0;
    currentBytesUnarchived = 0;
    totalUncompressedBytesInArchive = 0;
    totalFilesInArchive = 0;

    postMessage(new bitjs.archive.UnarchiveStartEvent());
    var bstream = new bitjs.io.BitStream(arrayBuffer, false /* rtl */);

    var header = new RarVolumeHeader(bstream);
    if (header.crc === 0x6152 &&
        header.headType === 0x72 &&
        header.flags.value === 0x1A21 &&
        header.headSize === 7)
    {
        info("Found RAR signature");

        var mhead = new RarVolumeHeader(bstream);
        if (mhead.headType != MAIN_HEAD) {
            info("Error! RAR did not include a MAIN_HEAD header");
        } else {
            var localFiles = [],
            localFile = null;
            do {
                try {
                    localFile = new RarLocalFile(bstream);
                    info("RAR localFile isValid=" + localFile.isValid + ", volume packSize=" + localFile.header.packSize);
                    if (localFile && localFile.isValid && localFile.header.packSize > 0) {
                        totalUncompressedBytesInArchive += localFile.header.unpackedSize;
                        localFiles.push(localFile);
                    } else if (localFile.header.packSize === 0 && localFile.header.unpackedSize === 0) {
                            localFile.isValid = true;
                    }
                } catch(err) {
                    break;
                }
                //info("bstream" + bstream.bytePtr+"/"+bstream.bytes.length);
            } while( localFile.isValid );
            totalFilesInArchive = localFiles.length;

            // now we have all information but things are unpacked
            // TODO: unpack
            localFiles = localFiles.sort(function(a,b) {
                var aname = a.filename.toLowerCase();
                var bname = b.filename.toLowerCase();
                return aname > bname ? 1 : -1;
            });

            info(localFiles.map(function(a){return a.filename}).join(', '));
            for (var i = 0; i < localFiles.length; ++i) {
                var localfile = localFiles[i];

                // update progress
                currentFilename = localfile.header.filename;
                currentBytesUnarchivedInFile = 0;

                // actually do the unzipping
                localfile.unrar();

                if (localfile.isValid) {
                    postMessage(new bitjs.archive.UnarchiveExtractEvent(localfile));
                    postProgress();
                }
            }

            postProgress();
        }
    }
    else {
        err("Invalid RAR file");
    }
    postMessage(new bitjs.archive.UnarchiveFinishEvent());
};

// event.data.file has the ArrayBuffer.
onmessage = function(event) {
    var ab = event.data.file;
    unrar(ab, true);
};