/*
 * 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 org.akvo.caddisfly.sensor.striptest.qrdetector;

import java.util.Arrays;

/**
 * <p>Represents a 2D matrix of bits. In function arguments below, and throughout the common
 * module, x is the column position, and y is the row position. The ordering is always x, y.
 * The origin is at the top-left.</p>
 * <p>
 * <p>Internally the bits are represented in a 1-D array of 32-bit ints. However, each row begins
 * with a new int. This is done intentionally so that we can copy out a row into a BitArray very
 * efficiently.</p>
 * <p>
 * <p>The ordering of bits is row-major. Within each int, the least significant bits are used first,
 * meaning they represent lower x values. This is compatible with BitArray's implementation.</p>
 *
 * @author Sean Owen
 * @author dswitkin@google.com (Daniel Switkin)
 */
public final class BitMatrix implements Cloneable {

    private final int width;
    private final int height;
    private final int rowSize;
    private final int[] bits;

    // A helper to construct a square matrix.
    public BitMatrix(int dimension) {
        this(dimension, dimension);
    }

    public BitMatrix(int width, int height) {
        if (width < 1 || height < 1) {
            throw new IllegalArgumentException("Both dimensions must be greater than 0");
        }
        this.width = width;
        this.height = height;
        this.rowSize = (width + 31) / 32;
        bits = new int[rowSize * height];
    }

    private BitMatrix(int width, int height, int rowSize, int[] bits) {
        this.width = width;
        this.height = height;
        this.rowSize = rowSize;
        this.bits = bits;
    }

    public static BitMatrix parse(String stringRepresentation, String setString, String unsetString) {
        if (stringRepresentation == null) {
            throw new IllegalArgumentException();
        }

        boolean[] bits = new boolean[stringRepresentation.length()];
        int bitsPos = 0;
        int rowStartPos = 0;
        int rowLength = -1;
        int nRows = 0;
        int pos = 0;
        while (pos < stringRepresentation.length()) {
            if (stringRepresentation.charAt(pos) == '\n' ||
                    stringRepresentation.charAt(pos) == '\r') {
                if (bitsPos > rowStartPos) {
                    if (rowLength == -1) {
                        rowLength = bitsPos - rowStartPos;
                    } else if (bitsPos - rowStartPos != rowLength) {
                        throw new IllegalArgumentException("row lengths do not match");
                    }
                    rowStartPos = bitsPos;
                    nRows++;
                }
                pos++;
            } else if (stringRepresentation.substring(pos, pos + setString.length()).equals(setString)) {
                pos += setString.length();
                bits[bitsPos] = true;
                bitsPos++;
            } else if (stringRepresentation.substring(pos, pos + unsetString.length()).equals(unsetString)) {
                pos += unsetString.length();
                bits[bitsPos] = false;
                bitsPos++;
            } else {
                throw new IllegalArgumentException(
                        "illegal character encountered: " + stringRepresentation.substring(pos));
            }
        }

        // no EOL at end?
        if (bitsPos > rowStartPos) {
            if (rowLength == -1) {
                rowLength = bitsPos - rowStartPos;
            } else if (bitsPos - rowStartPos != rowLength) {
                throw new IllegalArgumentException("row lengths do not match");
            }
            nRows++;
        }

        BitMatrix matrix = new BitMatrix(rowLength, nRows);
        for (int i = 0; i < bitsPos; i++) {
            if (bits[i]) {
                matrix.set(i % rowLength, i / rowLength);
            }
        }
        return matrix;
    }

    /**
     * <p>Gets the requested bit, where true means black.</p>
     *
     * @param x The horizontal component (i.e. which column)
     * @param y The vertical component (i.e. which row)
     * @return value of given bit in matrix
     */
    public boolean get(int x, int y) {
        int offset = y * rowSize + (x >> 5); /* divides by 32 */
        return ((bits[offset] >>> (x & 0x1f)) & 1) != 0;
    }

    /**
     * <p>Sets the given bit to true.</p>
     *
     * @param x The horizontal component (i.e. which column)
     * @param y The vertical component (i.e. which row)
     */
    public void set(int x, int y) {
        int offset = y * rowSize + (x >> 5); /* divides by 32 */
        bits[offset] |= 1 << (x & 0x1f);
    }

    public void unset(int x, int y) {
        int offset = y * rowSize + (x >> 5); /* divides by 32 */
        bits[offset] &= ~(1 << (x & 0x1f));
    }

    /**
     * <p>Flips the given bit.</p>
     *
     * @param x The horizontal component (i.e. which column)
     * @param y The vertical component (i.e. which row)
     */
    public void flip(int x, int y) {
        int offset = y * rowSize + (x / 32);
        bits[offset] ^= 1 << (x & 0x1f);
    }

    /**
     * Exclusive-or (XOR): Flip the bit in this {@code BitMatrix} if the corresponding
     * mask bit is set.
     *
     * @param mask XOR mask
     */
    public void xor(BitMatrix mask) {
        if (width != mask.getWidth() || height != mask.getHeight()
                || rowSize != mask.getRowSize()) {
            throw new IllegalArgumentException("input matrix dimensions do not match");
        }
        BitArray rowArray = new BitArray(width / 32 + 1);
        for (int y = 0; y < height; y++) {
            int offset = y * rowSize;
            int[] row = mask.getRow(y, rowArray).getBitArray();
            for (int x = 0; x < rowSize; x++) {
                bits[offset + x] ^= row[x];
            }
        }
    }

    /**
     * Clears all bits (sets to false).
     */
    public void clear() {
        int max = bits.length;
        for (int i = 0; i < max; i++) {
            bits[i] = 0;
        }
    }

    /**
     * <p>Sets a square region of the bit matrix to true.</p>
     *
     * @param left   The horizontal position to begin at (inclusive)
     * @param top    The vertical position to begin at (inclusive)
     * @param width  The width of the region
     * @param height The height of the region
     */
    public void setRegion(int left, int top, int width, int height) {
        if (top < 0 || left < 0) {
            throw new IllegalArgumentException("Left and top must be non-negative");
        }
        if (height < 1 || width < 1) {
            throw new IllegalArgumentException("Height and width must be at least 1");
        }
        int right = left + width;
        int bottom = top + height;
        if (bottom > this.height || right > this.width) {
            throw new IllegalArgumentException("The region must fit inside the matrix");
        }
        for (int y = top; y < bottom; y++) {
            int offset = y * rowSize;
            for (int x = left; x < right; x++) {
                bits[offset + (x / 32)] |= 1 << (x & 0x1f);
            }
        }
    }

    /**
     * A fast method to retrieve one row of data from the matrix as a BitArray.
     *
     * @param y   The row to retrieve
     * @param row An optional caller-allocated BitArray, will be allocated if null or too small
     * @return The resulting BitArray - this reference should always be used even when passing
     * your own row
     */
    public BitArray getRow(int y, BitArray row) {
        if (row == null || row.getSize() < width) {
            row = new BitArray(width);
        } else {
            row.clear();
        }
        int offset = y * rowSize;
        for (int x = 0; x < rowSize; x++) {
            row.setBulk(x * 32, bits[offset + x]);
        }
        return row;
    }

    /**
     * @param y   row to set
     * @param row {@link BitArray} to copy from
     */
    public void setRow(int y, BitArray row) {
        System.arraycopy(row.getBitArray(), 0, bits, y * rowSize, rowSize);
    }

    /**
     * Modifies this {@code BitMatrix} to represent the same but rotated 180 degrees
     */
    public void rotate180() {
        int width = getWidth();
        int height = getHeight();
        BitArray topRow = new BitArray(width);
        BitArray bottomRow = new BitArray(width);
        for (int i = 0; i < (height + 1) / 2; i++) {
            topRow = getRow(i, topRow);
            bottomRow = getRow(height - 1 - i, bottomRow);
            topRow.reverse();
            bottomRow.reverse();
            setRow(i, bottomRow);
            setRow(height - 1 - i, topRow);
        }
    }

    /**
     * This is useful in detecting the enclosing rectangle of a 'pure' barcode.
     *
     * @return {@code left,top,width,height} enclosing rectangle of all 1 bits, or null if it is all white
     */
    public int[] getEnclosingRectangle() {
        int left = width;
        int top = height;
        int right = -1;
        int bottom = -1;

        for (int y = 0; y < height; y++) {
            for (int x32 = 0; x32 < rowSize; x32++) {
                int theBits = bits[y * rowSize + x32];
                if (theBits != 0) {
                    if (y < top) {
                        top = y;
                    }
                    if (y > bottom) {
                        bottom = y;
                    }
                    if (x32 * 32 < left) {
                        int bit = 0;
                        while ((theBits << (31 - bit)) == 0) {
                            bit++;
                        }
                        if ((x32 * 32 + bit) < left) {
                            left = x32 * 32 + bit;
                        }
                    }
                    if (x32 * 32 + 31 > right) {
                        int bit = 31;
                        while ((theBits >>> bit) == 0) {
                            bit--;
                        }
                        if ((x32 * 32 + bit) > right) {
                            right = x32 * 32 + bit;
                        }
                    }
                }
            }
        }

        int width = right - left;
        int height = bottom - top;

        if (width < 0 || height < 0) {
            return null;
        }

        return new int[]{left, top, width, height};
    }

    /**
     * This is useful in detecting a corner of a 'pure' barcode.
     *
     * @return {@code x,y} coordinate of top-left-most 1 bit, or null if it is all white
     */
    public int[] getTopLeftOnBit() {
        int bitsOffset = 0;
        while (bitsOffset < bits.length && bits[bitsOffset] == 0) {
            bitsOffset++;
        }
        if (bitsOffset == bits.length) {
            return null;
        }
        int y = bitsOffset / rowSize;
        int x = (bitsOffset % rowSize) * 32;

        int theBits = bits[bitsOffset];
        int bit = 0;
        while ((theBits << (31 - bit)) == 0) {
            bit++;
        }
        x += bit;
        return new int[]{x, y};
    }

    public int[] getBottomRightOnBit() {
        int bitsOffset = bits.length - 1;
        while (bitsOffset >= 0 && bits[bitsOffset] == 0) {
            bitsOffset--;
        }
        if (bitsOffset < 0) {
            return null;
        }

        int y = bitsOffset / rowSize;
        int x = (bitsOffset % rowSize) * 32;

        int theBits = bits[bitsOffset];
        int bit = 31;
        while ((theBits >>> bit) == 0) {
            bit--;
        }
        x += bit;

        return new int[]{x, y};
    }

    /**
     * @return The width of the matrix
     */
    public int getWidth() {
        return width;
    }

    /**
     * @return The height of the matrix
     */
    public int getHeight() {
        return height;
    }

    /**
     * @return The row size of the matrix
     */
    public int getRowSize() {
        return rowSize;
    }

    @Override
    public boolean equals(Object o) {
        if (!(o instanceof BitMatrix)) {
            return false;
        }
        BitMatrix other = (BitMatrix) o;
        return width == other.width && height == other.height && rowSize == other.rowSize &&
                Arrays.equals(bits, other.bits);
    }

    @Override
    public int hashCode() {
        int hash = width;
        hash = 31 * hash + width;
        hash = 31 * hash + height;
        hash = 31 * hash + rowSize;
        hash = 31 * hash + Arrays.hashCode(bits);
        return hash;
    }

    /**
     * @return string representation using "X" for set and " " for unset bits
     */
    @Override
    public String toString() {
        return toString("X ", "  ");
    }

    /**
     * @param setString   representation of a set bit
     * @param unsetString representation of an unset bit
     * @return string representation of entire matrix utilizing given strings
     */
    public String toString(String setString, String unsetString) {
        return toString(setString, unsetString, "\n");
    }

    /**
     * @param setString     representation of a set bit
     * @param unsetString   representation of an unset bit
     * @param lineSeparator newline character in string representation
     * @return string representation of entire matrix utilizing given strings and line separator
     * @deprecated call {@link #toString(String, String)} only, which uses \n line separator always
     */
    @Deprecated
    public String toString(String setString, String unsetString, String lineSeparator) {
        StringBuilder result = new StringBuilder(height * (width + 1));
        for (int y = 0; y < height; y++) {
            for (int x = 0; x < width; x++) {
                result.append(get(x, y) ? setString : unsetString);
            }
            result.append(lineSeparator);
        }
        return result.toString();
    }

    @Override
    public BitMatrix clone() {
        return new BitMatrix(width, height, rowSize, bits.clone());
    }

}
