using System;
using System.Collections.Generic;
using System.Text;
/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace iTextSharp.text.pdf.qrcode {

    /**
     * @author satorux@google.com (Satoru Takabayashi) - creator
     * @author dswitkin@google.com (Daniel Switkin) - ported from C++
     */
    public sealed class Encoder {

        // The original table is defined in the table 5 of JISX0510:2004 (p.19).
        private static readonly int[] ALPHANUMERIC_TABLE = {
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  // 0x00-0x0f
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  // 0x10-0x1f
            36, -1, -1, -1, 37, 38, -1, -1, -1, -1, 39, 40, -1, 41, 42, 43,  // 0x20-0x2f
            0,   1,  2,  3,  4,  5,  6,  7,  8,  9, 44, -1, -1, -1, -1, -1,  // 0x30-0x3f
            -1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,  // 0x40-0x4f
            25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, -1, -1, -1, -1, -1   // 0x50-0x5f
        };

        private const String DEFAULT_BYTE_MODE_ENCODING = "ISO-8859-1";

        private Encoder() {
        }

        // The mask penalty calculation is complicated.  See Table 21 of JISX0510:2004 (p.45) for details.
        // Basically it applies four rules and summate all penalties.
        private static int CalculateMaskPenalty(ByteMatrix matrix) {
            int penalty = 0;
            penalty += MaskUtil.ApplyMaskPenaltyRule1(matrix);
            penalty += MaskUtil.ApplyMaskPenaltyRule2(matrix);
            penalty += MaskUtil.ApplyMaskPenaltyRule3(matrix);
            penalty += MaskUtil.ApplyMaskPenaltyRule4(matrix);
            return penalty;
        }

        /**
         *  Encode "bytes" with the error correction level "ecLevel". The encoding mode will be chosen
         * internally by ChooseMode(). On success, store the result in "qrCode".
         *
         * We recommend you to use QRCode.EC_LEVEL_L (the lowest level) for
         * "getECLevel" since our primary use is to show QR code on desktop screens. We don't need very
         * strong error correction for this purpose.
         *
         * Note that there is no way to encode bytes in MODE_KANJI. We might want to add EncodeWithMode()
         * with which clients can specify the encoding mode. For now, we don't need the functionality.
         */
        public static void Encode(String content, ErrorCorrectionLevel ecLevel, QRCode qrCode) {
            Encode(content, ecLevel, null, qrCode);
        }

        public static void Encode(String content, ErrorCorrectionLevel ecLevel, IDictionary<EncodeHintType, Object> hints,
            QRCode qrCode) {

            String encoding = null;
            if (hints != null && hints.ContainsKey(EncodeHintType.CHARACTER_SET))
                encoding = (string)hints[EncodeHintType.CHARACTER_SET];
            if (encoding == null) {
                encoding = DEFAULT_BYTE_MODE_ENCODING;
            }

            // Step 1: Choose the mode (encoding).
            Mode mode = ChooseMode(content, encoding);

            // Step 2: Append "bytes" into "dataBits" in appropriate encoding.
            BitVector dataBits = new BitVector();
            AppendBytes(content, mode, dataBits, encoding);
            // Step 3: Initialize QR code that can contain "dataBits".
            int numInputBytes = dataBits.SizeInBytes();
            InitQRCode(numInputBytes, ecLevel, mode, qrCode);

            // Step 4: Build another bit vector that contains header and data.
            BitVector headerAndDataBits = new BitVector();

            // Step 4.5: Append ECI message if applicable
            if (mode == Mode.BYTE && !DEFAULT_BYTE_MODE_ENCODING.Equals(encoding)) {
                CharacterSetECI eci = CharacterSetECI.GetCharacterSetECIByName(encoding);
                if (eci != null) {
                    AppendECI(eci, headerAndDataBits);
                }
            }

            AppendModeInfo(mode, headerAndDataBits);

            int numLetters = mode.Equals(Mode.BYTE) ? dataBits.SizeInBytes() : content.Length;
            AppendLengthInfo(numLetters, qrCode.GetVersion(), mode, headerAndDataBits);
            headerAndDataBits.AppendBitVector(dataBits);

            // Step 5: Terminate the bits properly.
            TerminateBits(qrCode.GetNumDataBytes(), headerAndDataBits);

            // Step 6: Interleave data bits with error correction code.
            BitVector finalBits = new BitVector();
            InterleaveWithECBytes(headerAndDataBits, qrCode.GetNumTotalBytes(), qrCode.GetNumDataBytes(),
                qrCode.GetNumRSBlocks(), finalBits);

            // Step 7: Choose the mask pattern and set to "qrCode".
            ByteMatrix matrix = new ByteMatrix(qrCode.GetMatrixWidth(), qrCode.GetMatrixWidth());
            qrCode.SetMaskPattern(ChooseMaskPattern(finalBits, qrCode.GetECLevel(), qrCode.GetVersion(),
                matrix));

            // Step 8.  Build the matrix and set it to "qrCode".
            MatrixUtil.BuildMatrix(finalBits, qrCode.GetECLevel(), qrCode.GetVersion(),
                qrCode.GetMaskPattern(), matrix);
            qrCode.SetMatrix(matrix);
            // Step 9.  Make sure we have a valid QR Code.
            if (!qrCode.IsValid()) {
                throw new WriterException("Invalid QR code: " + qrCode.ToString());
            }
        }

        /**
         * @return the code point of the table used in alphanumeric mode or
         *  -1 if there is no corresponding code in the table.
         */
        static int GetAlphanumericCode(int code) {
            if (code < ALPHANUMERIC_TABLE.Length) {
                return ALPHANUMERIC_TABLE[code];
            }
            return -1;
        }

        public static Mode ChooseMode(String content) {
            return ChooseMode(content, null);
        }

        /**
         * Choose the best mode by examining the content. Note that 'encoding' is used as a hint;
         * if it is Shift_JIS, and the input is only double-byte Kanji, then we return {@link Mode#KANJI}.
         */
        public static Mode ChooseMode(String content, String encoding) {
            if ("Shift_JIS".Equals(encoding)) {
                // Choose Kanji mode if all input are double-byte characters
                return IsOnlyDoubleByteKanji(content) ? Mode.KANJI : Mode.BYTE;
            }
            bool hasNumeric = false;
            bool hasAlphanumeric = false;
            for (int i = 0; i < content.Length; ++i) {
                char c = content[i];
                if (c >= '0' && c <= '9') {
                    hasNumeric = true;
                }
                else if (GetAlphanumericCode(c) != -1) {
                    hasAlphanumeric = true;
                }
                else {
                    return Mode.BYTE;
                }
            }
            if (hasAlphanumeric) {
                return Mode.ALPHANUMERIC;
            }
            else if (hasNumeric) {
                return Mode.NUMERIC;
            }
            return Mode.BYTE;
        }

        private static bool IsOnlyDoubleByteKanji(String content) {
            byte[] bytes;
            try {
                bytes = Encoding.GetEncoding("Shift_JIS").GetBytes(content);
            }
            catch {
                return false;
            }
            int length = bytes.Length;
            if (length % 2 != 0) {
                return false;
            }
            for (int i = 0; i < length; i += 2) {
                int byte1 = bytes[i] & 0xFF;
                if ((byte1 < 0x81 || byte1 > 0x9F) && (byte1 < 0xE0 || byte1 > 0xEB)) {
                    return false;
                }
            }
            return true;
        }

        private static int ChooseMaskPattern(BitVector bits, ErrorCorrectionLevel ecLevel, int version,
            ByteMatrix matrix) {

            int minPenalty = int.MaxValue;  // Lower penalty is better.
            int bestMaskPattern = -1;
            // We try all mask patterns to choose the best one.
            for (int maskPattern = 0; maskPattern < QRCode.NUM_MASK_PATTERNS; maskPattern++) {
                MatrixUtil.BuildMatrix(bits, ecLevel, version, maskPattern, matrix);
                int penalty = CalculateMaskPenalty(matrix);
                if (penalty < minPenalty) {
                    minPenalty = penalty;
                    bestMaskPattern = maskPattern;
                }
            }
            return bestMaskPattern;
        }

        /**
         * Initialize "qrCode" according to "numInputBytes", "ecLevel", and "mode". On success,
         * modify "qrCode".
         */
        private static void InitQRCode(int numInputBytes, ErrorCorrectionLevel ecLevel, Mode mode,
            QRCode qrCode) {
            qrCode.SetECLevel(ecLevel);
            qrCode.SetMode(mode);

            // In the following comments, we use numbers of Version 7-H.
            for (int versionNum = 1; versionNum <= 40; versionNum++) {
                Version version = Version.GetVersionForNumber(versionNum);
                // numBytes = 196
                int numBytes = version.GetTotalCodewords();
                // getNumECBytes = 130
                Version.ECBlocks ecBlocks = version.GetECBlocksForLevel(ecLevel);
                int numEcBytes = ecBlocks.GetTotalECCodewords();
                // getNumRSBlocks = 5
                int numRSBlocks = ecBlocks.GetNumBlocks();
                // getNumDataBytes = 196 - 130 = 66
                int numDataBytes = numBytes - numEcBytes;
                // We want to choose the smallest version which can contain data of "numInputBytes" + some
                // extra bits for the header (mode info and length info). The header can be three bytes
                // (precisely 4 + 16 bits) at most. Hence we do +3 here.
                if (numDataBytes >= numInputBytes + 3) {
                    // Yay, we found the proper rs block info!
                    qrCode.SetVersion(versionNum);
                    qrCode.SetNumTotalBytes(numBytes);
                    qrCode.SetNumDataBytes(numDataBytes);
                    qrCode.SetNumRSBlocks(numRSBlocks);
                    // getNumECBytes = 196 - 66 = 130
                    qrCode.SetNumECBytes(numEcBytes);
                    // matrix width = 21 + 6 * 4 = 45
                    qrCode.SetMatrixWidth(version.GetDimensionForVersion());
                    return;
                }
            }
            throw new WriterException("Cannot find proper rs block info (input data too big?)");
        }

        /**
         * Terminate bits as described in 8.4.8 and 8.4.9 of JISX0510:2004 (p.24).
         */
        static void TerminateBits(int numDataBytes, BitVector bits) {
            int capacity = numDataBytes << 3;
            if (bits.Size() > capacity) {
                throw new WriterException("data bits cannot fit in the QR Code" + bits.Size() + " > " +
                    capacity);
            }
            // Append termination bits. See 8.4.8 of JISX0510:2004 (p.24) for details.
            // TODO: srowen says we can remove this for loop, since the 4 terminator bits are optional if
            // the last byte has less than 4 bits left. So it amounts to padding the last byte with zeroes
            // either way.
            for (int i = 0; i < 4 && bits.Size() < capacity; ++i) {
                bits.AppendBit(0);
            }
            int numBitsInLastByte = bits.Size() % 8;
            // If the last byte isn't 8-bit aligned, we'll add padding bits.
            if (numBitsInLastByte > 0) {
                int numPaddingBits = 8 - numBitsInLastByte;
                for (int i = 0; i < numPaddingBits; ++i) {
                    bits.AppendBit(0);
                }
            }
            // Should be 8-bit aligned here.
            if (bits.Size() % 8 != 0) {
                throw new WriterException("Number of bits is not a multiple of 8");
            }
            // If we have more space, we'll fill the space with padding patterns defined in 8.4.9 (p.24).
            int numPaddingBytes = numDataBytes - bits.SizeInBytes();
            for (int i = 0; i < numPaddingBytes; ++i) {
                if (i % 2 == 0) {
                    bits.AppendBits(0xec, 8);
                }
                else {
                    bits.AppendBits(0x11, 8);
                }
            }
            if (bits.Size() != capacity) {
                throw new WriterException("Bits size does not equal capacity");
            }
        }

        /**
         * Get number of data bytes and number of error correction bytes for block id "blockID". Store
         * the result in "numDataBytesInBlock", and "numECBytesInBlock". See table 12 in 8.5.1 of
         * JISX0510:2004 (p.30)
         */
        static void GetNumDataBytesAndNumECBytesForBlockID(int numTotalBytes, int numDataBytes,
            int numRSBlocks, int blockID, int[] numDataBytesInBlock,
            int[] numECBytesInBlock) {
            if (blockID >= numRSBlocks) {
                throw new WriterException("Block ID too large");
            }
            // numRsBlocksInGroup2 = 196 % 5 = 1
            int numRsBlocksInGroup2 = numTotalBytes % numRSBlocks;
            // numRsBlocksInGroup1 = 5 - 1 = 4
            int numRsBlocksInGroup1 = numRSBlocks - numRsBlocksInGroup2;
            // numTotalBytesInGroup1 = 196 / 5 = 39
            int numTotalBytesInGroup1 = numTotalBytes / numRSBlocks;
            // numTotalBytesInGroup2 = 39 + 1 = 40
            int numTotalBytesInGroup2 = numTotalBytesInGroup1 + 1;
            // numDataBytesInGroup1 = 66 / 5 = 13
            int numDataBytesInGroup1 = numDataBytes / numRSBlocks;
            // numDataBytesInGroup2 = 13 + 1 = 14
            int numDataBytesInGroup2 = numDataBytesInGroup1 + 1;
            // numEcBytesInGroup1 = 39 - 13 = 26
            int numEcBytesInGroup1 = numTotalBytesInGroup1 - numDataBytesInGroup1;
            // numEcBytesInGroup2 = 40 - 14 = 26
            int numEcBytesInGroup2 = numTotalBytesInGroup2 - numDataBytesInGroup2;
            // Sanity checks.
            // 26 = 26
            if (numEcBytesInGroup1 != numEcBytesInGroup2) {
                throw new WriterException("EC bytes mismatch");
            }
            // 5 = 4 + 1.
            if (numRSBlocks != numRsBlocksInGroup1 + numRsBlocksInGroup2) {
                throw new WriterException("RS blocks mismatch");
            }
            // 196 = (13 + 26) * 4 + (14 + 26) * 1
            if (numTotalBytes !=
                ((numDataBytesInGroup1 + numEcBytesInGroup1) *
                    numRsBlocksInGroup1) +
                    ((numDataBytesInGroup2 + numEcBytesInGroup2) *
                        numRsBlocksInGroup2)) {
                throw new WriterException("Total bytes mismatch");
            }

            if (blockID < numRsBlocksInGroup1) {
                numDataBytesInBlock[0] = numDataBytesInGroup1;
                numECBytesInBlock[0] = numEcBytesInGroup1;
            }
            else {
                numDataBytesInBlock[0] = numDataBytesInGroup2;
                numECBytesInBlock[0] = numEcBytesInGroup2;
            }
        }

        /**
         * Interleave "bits" with corresponding error correction bytes. On success, store the result in
         * "result". The interleave rule is complicated. See 8.6 of JISX0510:2004 (p.37) for details.
         */
        static void InterleaveWithECBytes(BitVector bits, int numTotalBytes,
            int numDataBytes, int numRSBlocks, BitVector result) {

            // "bits" must have "getNumDataBytes" bytes of data.
            if (bits.SizeInBytes() != numDataBytes) {
                throw new WriterException("Number of bits and data bytes does not match");
            }

            // Step 1.  Divide data bytes into blocks and generate error correction bytes for them. We'll
            // store the divided data bytes blocks and error correction bytes blocks into "blocks".
            int dataBytesOffset = 0;
            int maxNumDataBytes = 0;
            int maxNumEcBytes = 0;

            // Since, we know the number of reedsolmon blocks, we can initialize the vector with the number.
            List<BlockPair> blocks = new List<BlockPair>(numRSBlocks);

            for (int i = 0; i < numRSBlocks; ++i) {
                int[] numDataBytesInBlock = new int[1];
                int[] numEcBytesInBlock = new int[1];
                GetNumDataBytesAndNumECBytesForBlockID(
                    numTotalBytes, numDataBytes, numRSBlocks, i,
                    numDataBytesInBlock, numEcBytesInBlock);

                ByteArray dataBytes = new ByteArray();
                dataBytes.Set(bits.GetArray(), dataBytesOffset, numDataBytesInBlock[0]);
                ByteArray ecBytes = GenerateECBytes(dataBytes, numEcBytesInBlock[0]);
                blocks.Add(new BlockPair(dataBytes, ecBytes));

                maxNumDataBytes = Math.Max(maxNumDataBytes, dataBytes.Size());
                maxNumEcBytes = Math.Max(maxNumEcBytes, ecBytes.Size());
                dataBytesOffset += numDataBytesInBlock[0];
            }
            if (numDataBytes != dataBytesOffset) {
                throw new WriterException("Data bytes does not match offset");
            }

            // First, place data blocks.
            for (int i = 0; i < maxNumDataBytes; ++i) {
                for (int j = 0; j < blocks.Count; ++j) {
                    ByteArray dataBytes = blocks[j].GetDataBytes();
                    if (i < dataBytes.Size()) {
                        result.AppendBits(dataBytes.At(i), 8);
                    }
                }
            }
            // Then, place error correction blocks.
            for (int i = 0; i < maxNumEcBytes; ++i) {
                for (int j = 0; j < blocks.Count; ++j) {
                    ByteArray ecBytes = blocks[j].GetErrorCorrectionBytes();
                    if (i < ecBytes.Size()) {
                        result.AppendBits(ecBytes.At(i), 8);
                    }
                }
            }
            if (numTotalBytes != result.SizeInBytes()) {  // Should be same.
                throw new WriterException("Interleaving error: " + numTotalBytes + " and " +
                    result.SizeInBytes() + " differ.");
            }
        }

        static ByteArray GenerateECBytes(ByteArray dataBytes, int numEcBytesInBlock) {
            int numDataBytes = dataBytes.Size();
            int[] toEncode = new int[numDataBytes + numEcBytesInBlock];
            for (int i = 0; i < numDataBytes; i++) {
                toEncode[i] = dataBytes.At(i);
            }
            new ReedSolomonEncoder(GF256.QR_CODE_FIELD).Encode(toEncode, numEcBytesInBlock);

            ByteArray ecBytes = new ByteArray(numEcBytesInBlock);
            for (int i = 0; i < numEcBytesInBlock; i++) {
                ecBytes.Set(i, toEncode[numDataBytes + i]);
            }
            return ecBytes;
        }

        /**
         * Append mode info. On success, store the result in "bits".
         */
        static void AppendModeInfo(Mode mode, BitVector bits) {
            bits.AppendBits(mode.GetBits(), 4);
        }


        /**
         * Append length info. On success, store the result in "bits".
         */
        static void AppendLengthInfo(int numLetters, int version, Mode mode, BitVector bits) {
            int numBits = mode.GetCharacterCountBits(Version.GetVersionForNumber(version));
            if (numLetters > ((1 << numBits) - 1)) {
                throw new WriterException(numLetters + "is bigger than" + ((1 << numBits) - 1));
            }
            bits.AppendBits(numLetters, numBits);
        }

        /**
         * Append "bytes" in "mode" mode (encoding) into "bits". On success, store the result in "bits".
         */
        static void AppendBytes(String content, Mode mode, BitVector bits, String encoding) {
            if (mode.Equals(Mode.NUMERIC)) {
                AppendNumericBytes(content, bits);
            }
            else if (mode.Equals(Mode.ALPHANUMERIC)) {
                AppendAlphanumericBytes(content, bits);
            }
            else if (mode.Equals(Mode.BYTE)) {
                Append8BitBytes(content, bits, encoding);
            }
            else if (mode.Equals(Mode.KANJI)) {
                AppendKanjiBytes(content, bits);
            }
            else {
                throw new WriterException("Invalid mode: " + mode);
            }
        }

        static void AppendNumericBytes(String content, BitVector bits) {
            int length = content.Length;
            int i = 0;
            while (i < length) {
                int num1 = content[i] - '0';
                if (i + 2 < length) {
                    // Encode three numeric letters in ten bits.
                    int num2 = content[i + 1] - '0';
                    int num3 = content[i + 2] - '0';
                    bits.AppendBits(num1 * 100 + num2 * 10 + num3, 10);
                    i += 3;
                }
                else if (i + 1 < length) {
                    // Encode two numeric letters in seven bits.
                    int num2 = content[i + 1] - '0';
                    bits.AppendBits(num1 * 10 + num2, 7);
                    i += 2;
                }
                else {
                    // Encode one numeric letter in four bits.
                    bits.AppendBits(num1, 4);
                    i++;
                }
            }
        }

        static void AppendAlphanumericBytes(String content, BitVector bits) {
            int length = content.Length;
            int i = 0;
            while (i < length) {
                int code1 = GetAlphanumericCode(content[i]);
                if (code1 == -1) {
                    throw new WriterException();
                }
                if (i + 1 < length) {
                    int code2 = GetAlphanumericCode(content[i + 1]);
                    if (code2 == -1) {
                        throw new WriterException();
                    }
                    // Encode two alphanumeric letters in 11 bits.
                    bits.AppendBits(code1 * 45 + code2, 11);
                    i += 2;
                }
                else {
                    // Encode one alphanumeric letter in six bits.
                    bits.AppendBits(code1, 6);
                    i++;
                }
            }
        }

        static void Append8BitBytes(String content, BitVector bits, String encoding) {
            byte[] bytes;
            try {
                bytes = Encoding.GetEncoding(encoding).GetBytes(content);
            }
            catch (Exception uee) {
                throw new WriterException(uee.Message);
            }
            for (int i = 0; i < bytes.Length; ++i) {
                bits.AppendBits(bytes[i], 8);
            }
        }

        static void AppendKanjiBytes(String content, BitVector bits) {
            byte[] bytes;
            try {
                bytes = Encoding.GetEncoding("Shift_JIS").GetBytes(content);
            }
            catch (Exception uee) {
                throw new WriterException(uee.Message);
            }
            int length = bytes.Length;
            for (int i = 0; i < length; i += 2) {
                int byte1 = bytes[i] & 0xFF;
                int byte2 = bytes[i + 1] & 0xFF;
                int code = (byte1 << 8) | byte2;
                int subtracted = -1;
                if (code >= 0x8140 && code <= 0x9ffc) {
                    subtracted = code - 0x8140;
                }
                else if (code >= 0xe040 && code <= 0xebbf) {
                    subtracted = code - 0xc140;
                }
                if (subtracted == -1) {
                    throw new WriterException("Invalid byte sequence");
                }
                int encoded = ((subtracted >> 8) * 0xc0) + (subtracted & 0xff);
                bits.AppendBits(encoded, 13);
            }
        }

        private static void AppendECI(CharacterSetECI eci, BitVector bits) {
            bits.AppendBits(Mode.ECI.GetBits(), 4);
            // This is correct for values up to 127, which is all we need now.
            bits.AppendBits(eci.GetValue(), 8);
        }
    }
}