/*
 * Copyright 2007 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.
 */

package com.google.zxing.datamatrix.decoder;

import com.google.zxing.FormatException;
import com.google.zxing.common.BitMatrix;

/**
 * @author bbrown@google.com (Brian Brown)
 */
final class BitMatrixParser {

  private final BitMatrix mappingBitMatrix;
  private final BitMatrix readMappingMatrix;
  private final Version version;

  /**
   * @param bitMatrix {@link BitMatrix} to parse
   * @throws FormatException if dimension is < 8 or > 144 or not 0 mod 2
   */
  BitMatrixParser(BitMatrix bitMatrix) throws FormatException {
    int dimension = bitMatrix.getHeight();
    if (dimension < 8 || dimension > 144 || (dimension & 0x01) != 0) {
      throw FormatException.getFormatInstance();
    }

    version = readVersion(bitMatrix);
    this.mappingBitMatrix = extractDataRegion(bitMatrix);
    this.readMappingMatrix = new BitMatrix(this.mappingBitMatrix.getWidth(), this.mappingBitMatrix.getHeight());
  }

  Version getVersion() {
    return version;
  }

  /**
   * <p>Creates the version object based on the dimension of the original bit matrix from 
   * the datamatrix code.</p>
   *
   * <p>See ISO 16022:2006 Table 7 - ECC 200 symbol attributes</p>
   *
   * @param bitMatrix Original {@link BitMatrix} including alignment patterns
   * @return {@link Version} encapsulating the Data Matrix Code's "version"
   * @throws FormatException if the dimensions of the mapping matrix are not valid
   * Data Matrix dimensions.
   */
  private static Version readVersion(BitMatrix bitMatrix) throws FormatException {
    int numRows = bitMatrix.getHeight();
    int numColumns = bitMatrix.getWidth();
    return Version.getVersionForDimensions(numRows, numColumns);
  }

  /**
   * <p>Reads the bits in the {@link BitMatrix} representing the mapping matrix (No alignment patterns)
   * in the correct order in order to reconstitute the codewords bytes contained within the
   * Data Matrix Code.</p>
   *
   * @return bytes encoded within the Data Matrix Code
   * @throws FormatException if the exact number of bytes expected is not read
   */
  byte[] readCodewords() throws FormatException {

    byte[] result = new byte[version.getTotalCodewords()];
    int resultOffset = 0;

    int row = 4;
    int column = 0;

    int numRows = mappingBitMatrix.getHeight();
    int numColumns = mappingBitMatrix.getWidth();

    boolean corner1Read = false;
    boolean corner2Read = false;
    boolean corner3Read = false;
    boolean corner4Read = false;

    // Read all of the codewords
    do {
      // Check the four corner cases
      if ((row == numRows) && (column == 0) && !corner1Read) {
        result[resultOffset++] = (byte) readCorner1(numRows, numColumns);
        row -= 2;
        column += 2;
        corner1Read = true;
      } else if ((row == numRows - 2) && (column == 0) && ((numColumns & 0x03) != 0) && !corner2Read) {
        result[resultOffset++] = (byte) readCorner2(numRows, numColumns);
        row -= 2;
        column += 2;
        corner2Read = true;
      } else if ((row == numRows + 4) && (column == 2) && ((numColumns & 0x07) == 0) && !corner3Read) {
        result[resultOffset++] = (byte) readCorner3(numRows, numColumns);
        row -= 2;
        column += 2;
        corner3Read = true;
      } else if ((row == numRows - 2) && (column == 0) && ((numColumns & 0x07) == 4) && !corner4Read) {
        result[resultOffset++] = (byte) readCorner4(numRows, numColumns);
        row -= 2;
        column += 2;
        corner4Read = true;
      } else {
        // Sweep upward diagonally to the right
        do {
          if ((row < numRows) && (column >= 0) && !readMappingMatrix.get(column, row)) {
            result[resultOffset++] = (byte) readUtah(row, column, numRows, numColumns);
          }
          row -= 2;
          column += 2;
        } while ((row >= 0) && (column < numColumns));
        row += 1;
        column += 3;

        // Sweep downward diagonally to the left
        do {
          if ((row >= 0) && (column < numColumns) && !readMappingMatrix.get(column, row)) {
             result[resultOffset++] = (byte) readUtah(row, column, numRows, numColumns);
          }
          row += 2;
          column -= 2;
        } while ((row < numRows) && (column >= 0));
        row += 3;
        column += 1;
      }
    } while ((row < numRows) || (column < numColumns));

    if (resultOffset != version.getTotalCodewords()) {
      throw FormatException.getFormatInstance();
    }
    return result;
  }

  /**
   * <p>Reads a bit of the mapping matrix accounting for boundary wrapping.</p>
   *
   * @param row Row to read in the mapping matrix
   * @param column Column to read in the mapping matrix
   * @param numRows Number of rows in the mapping matrix
   * @param numColumns Number of columns in the mapping matrix
   * @return value of the given bit in the mapping matrix
   */
  private boolean readModule(int row, int column, int numRows, int numColumns) {
    // Adjust the row and column indices based on boundary wrapping
    if (row < 0) {
      row += numRows;
      column += 4 - ((numRows + 4) & 0x07);
    }
    if (column < 0) {
      column += numColumns;
      row += 4 - ((numColumns + 4) & 0x07);
    }
    readMappingMatrix.set(column, row);
    return mappingBitMatrix.get(column, row);
  }

  /**
   * <p>Reads the 8 bits of the standard Utah-shaped pattern.</p>
   *
   * <p>See ISO 16022:2006, 5.8.1 Figure 6</p>
   *
   * @param row Current row in the mapping matrix, anchored at the 8th bit (LSB) of the pattern
   * @param column Current column in the mapping matrix, anchored at the 8th bit (LSB) of the pattern
   * @param numRows Number of rows in the mapping matrix
   * @param numColumns Number of columns in the mapping matrix
   * @return byte from the utah shape
   */
  private int readUtah(int row, int column, int numRows, int numColumns) {
    int currentByte = 0;
    if (readModule(row - 2, column - 2, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(row - 2, column - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(row - 1, column - 2, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(row - 1, column - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(row - 1, column, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(row, column - 2, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(row, column - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(row, column, numRows, numColumns)) {
      currentByte |= 1;
    }
    return currentByte;
  }

  /**
   * <p>Reads the 8 bits of the special corner condition 1.</p>
   *
   * <p>See ISO 16022:2006, Figure F.3</p>
   *
   * @param numRows Number of rows in the mapping matrix
   * @param numColumns Number of columns in the mapping matrix
   * @return byte from the Corner condition 1
   */
  private int readCorner1(int numRows, int numColumns) {
    int currentByte = 0;
    if (readModule(numRows - 1, 0, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(numRows - 1, 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(numRows - 1, 2, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(0, numColumns - 2, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(0, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(1, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(2, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(3, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    return currentByte;
  }

  /**
   * <p>Reads the 8 bits of the special corner condition 2.</p>
   *
   * <p>See ISO 16022:2006, Figure F.4</p>
   *
   * @param numRows Number of rows in the mapping matrix
   * @param numColumns Number of columns in the mapping matrix
   * @return byte from the Corner condition 2
   */
  private int readCorner2(int numRows, int numColumns) {
    int currentByte = 0;
    if (readModule(numRows - 3, 0, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(numRows - 2, 0, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(numRows - 1, 0, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(0, numColumns - 4, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(0, numColumns - 3, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(0, numColumns - 2, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(0, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(1, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    return currentByte;
  }

  /**
   * <p>Reads the 8 bits of the special corner condition 3.</p>
   *
   * <p>See ISO 16022:2006, Figure F.5</p>
   *
   * @param numRows Number of rows in the mapping matrix
   * @param numColumns Number of columns in the mapping matrix
   * @return byte from the Corner condition 3
   */
  private int readCorner3(int numRows, int numColumns) {
    int currentByte = 0;
    if (readModule(numRows - 1, 0, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(numRows - 1, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(0, numColumns - 3, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(0, numColumns - 2, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(0, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(1, numColumns - 3, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(1, numColumns - 2, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(1, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    return currentByte;
  }

  /**
   * <p>Reads the 8 bits of the special corner condition 4.</p>
   *
   * <p>See ISO 16022:2006, Figure F.6</p>
   *
   * @param numRows Number of rows in the mapping matrix
   * @param numColumns Number of columns in the mapping matrix
   * @return byte from the Corner condition 4
   */
  private int readCorner4(int numRows, int numColumns) {
    int currentByte = 0;
    if (readModule(numRows - 3, 0, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(numRows - 2, 0, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(numRows - 1, 0, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(0, numColumns - 2, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(0, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(1, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(2, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    currentByte <<= 1;
    if (readModule(3, numColumns - 1, numRows, numColumns)) {
      currentByte |= 1;
    }
    return currentByte;
  }

  /**
   * <p>Extracts the data region from a {@link BitMatrix} that contains
   * alignment patterns.</p>
   *
   * @param bitMatrix Original {@link BitMatrix} with alignment patterns
   * @return BitMatrix that has the alignment patterns removed
   */
  private BitMatrix extractDataRegion(BitMatrix bitMatrix) {
    int symbolSizeRows = version.getSymbolSizeRows();
    int symbolSizeColumns = version.getSymbolSizeColumns();

    if (bitMatrix.getHeight() != symbolSizeRows) {
      throw new IllegalArgumentException("Dimension of bitMatrix must match the version size");
    }

    int dataRegionSizeRows = version.getDataRegionSizeRows();
    int dataRegionSizeColumns = version.getDataRegionSizeColumns();

    int numDataRegionsRow = symbolSizeRows / dataRegionSizeRows;
    int numDataRegionsColumn = symbolSizeColumns / dataRegionSizeColumns;

    int sizeDataRegionRow = numDataRegionsRow * dataRegionSizeRows;
    int sizeDataRegionColumn = numDataRegionsColumn * dataRegionSizeColumns;

    BitMatrix bitMatrixWithoutAlignment = new BitMatrix(sizeDataRegionColumn, sizeDataRegionRow);
    for (int dataRegionRow = 0; dataRegionRow < numDataRegionsRow; ++dataRegionRow) {
      int dataRegionRowOffset = dataRegionRow * dataRegionSizeRows;
      for (int dataRegionColumn = 0; dataRegionColumn < numDataRegionsColumn; ++dataRegionColumn) {
        int dataRegionColumnOffset = dataRegionColumn * dataRegionSizeColumns;
        for (int i = 0; i < dataRegionSizeRows; ++i) {
          int readRowOffset = dataRegionRow * (dataRegionSizeRows + 2) + 1 + i;
          int writeRowOffset = dataRegionRowOffset + i;
          for (int j = 0; j < dataRegionSizeColumns; ++j) {
            int readColumnOffset = dataRegionColumn * (dataRegionSizeColumns + 2) + 1 + j;
            if (bitMatrix.get(readColumnOffset, readRowOffset)) {
              int writeColumnOffset = dataRegionColumnOffset + j;
              bitMatrixWithoutAlignment.set(writeColumnOffset, writeRowOffset);
            }
          }
        }
      }
    }
    return bitMatrixWithoutAlignment;
  }

}
