/*
 * 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.
 */

/*namespace com.google.zxing.qrcode.detector {*/

import DecodeHintType from './../../DecodeHintType';
import ResultPoint from './../../ResultPoint';
import ResultPointCallback from './../../ResultPointCallback';
import BitMatrix from './../../common/BitMatrix';
import FinderPattern from './FinderPattern';
import FinderPatternInfo from './FinderPatternInfo';
import Exception from './../../Exception';

/*import java.io.Serializable;*/
/*import java.util.ArrayList;*/
/*import java.util.Collections;*/
/*import java.util.Comparator;*/
/*import java.util.List;*/
/*import java.util.Map;*/

/**
 * <p>This class attempts to find finder patterns in a QR Code. Finder patterns are the square
 * markers at three corners of a QR Code.</p>
 *
 * <p>This class is thread-safe but not reentrant. Each thread must allocate its own object.
 *
 * @author Sean Owen
 */
export default class FinderPatternFinder {

    private static CENTER_QUORUM = 2;
    protected static MIN_SKIP = 3; // 1 pixel/module times 3 modules/center
    protected static MAX_MODULES = 57; // support up to version 10 for mobile clients

    private possibleCenters: FinderPattern[];
    private hasSkipped: boolean;
    private crossCheckStateCount: Int32Array;

    /**
     * <p>Creates a finder that will search the image for three finder patterns.</p>
     *
     * @param image image to search
     */
    // public constructor(image: BitMatrix) {
    //   this(image, null)
    // }

    public constructor(private image: BitMatrix, private resultPointCallback: ResultPointCallback) {
        this.possibleCenters = [];
        this.crossCheckStateCount = new Int32Array(5);
        this.resultPointCallback = resultPointCallback;
    }

    protected getImage(): BitMatrix {
        return this.image;
    }

    protected getPossibleCenters(): FinderPattern[] {
        return this.possibleCenters;
    }

    public find(hints: Map<DecodeHintType, any>): FinderPatternInfo /*throws NotFoundException */ {
        const tryHarder: boolean = (hints !== null && hints !== undefined) && undefined !== hints.get(DecodeHintType.TRY_HARDER);
        const pureBarcode: boolean = (hints !== null && hints !== undefined) && undefined !== hints.get(DecodeHintType.PURE_BARCODE);
        const image = this.image;
        const maxI = image.getHeight();
        const maxJ = image.getWidth();
        // We are looking for black/white/black/white/black modules in
        // 1:1:3:1:1 ratio; this tracks the number of such modules seen so far

        // Let's assume that the maximum version QR Code we support takes up 1/4 the height of the
        // image, and then account for the center being 3 modules in size. This gives the smallest
        // number of pixels the center could be, so skip this often. When trying harder, look for all
        // QR versions regardless of how dense they are.
        let iSkip = Math.floor((3 * maxI) / (4 * FinderPatternFinder.MAX_MODULES));
        if (iSkip < FinderPatternFinder.MIN_SKIP || tryHarder) {
            iSkip = FinderPatternFinder.MIN_SKIP;
        }

        let done: boolean = false;
        const stateCount = new Int32Array(5);
        for (let i = iSkip - 1; i < maxI && !done; i += iSkip) {
            // Get a row of black/white values
            stateCount[0] = 0;
            stateCount[1] = 0;
            stateCount[2] = 0;
            stateCount[3] = 0;
            stateCount[4] = 0;
            let currentState = 0;
            for (let j = 0; j < maxJ; j++) {
                if (image.get(j, i)) {
                    // Black pixel
                    if ((currentState & 1) === 1) { // Counting white pixels
                        currentState++;
                    }
                    stateCount[currentState]++;
                } else { // White pixel
                    if ((currentState & 1) === 0) { // Counting black pixels
                        if (currentState === 4) { // A winner?
                            if (FinderPatternFinder.foundPatternCross(stateCount)) { // Yes
                                const confirmed: boolean = this.handlePossibleCenter(stateCount, i, j, pureBarcode);
                                if (confirmed === true) {
                                    // Start examining every other line. Checking each line turned out to be too
                                    // expensive and didn't improve performance.
                                    iSkip = 2;
                                    if (this.hasSkipped === true) {
                                        done = this.haveMultiplyConfirmedCenters();
                                    } else {
                                        const rowSkip = this.findRowSkip();
                                        if (rowSkip > stateCount[2]) {
                                            // Skip rows between row of lower confirmed center
                                            // and top of presumed third confirmed center
                                            // but back up a bit to get a full chance of detecting
                                            // it, entire width of center of finder pattern

                                            // Skip by rowSkip, but back off by stateCount[2] (size of last center
                                            // of pattern we saw) to be conservative, and also back off by iSkip which
                                            // is about to be re-added
                                            i += rowSkip - stateCount[2] - iSkip;
                                            j = maxJ - 1;
                                        }
                                    }
                                } else {
                                    stateCount[0] = stateCount[2];
                                    stateCount[1] = stateCount[3];
                                    stateCount[2] = stateCount[4];
                                    stateCount[3] = 1;
                                    stateCount[4] = 0;
                                    currentState = 3;
                                    continue;
                                }
                                // Clear state to start looking again
                                currentState = 0;
                                stateCount[0] = 0;
                                stateCount[1] = 0;
                                stateCount[2] = 0;
                                stateCount[3] = 0;
                                stateCount[4] = 0;
                            } else { // No, shift counts back by two
                                stateCount[0] = stateCount[2];
                                stateCount[1] = stateCount[3];
                                stateCount[2] = stateCount[4];
                                stateCount[3] = 1;
                                stateCount[4] = 0;
                                currentState = 3;
                            }
                        } else {
                            stateCount[++currentState]++;
                        }
                    } else { // Counting white pixels
                        stateCount[currentState]++;
                    }
                }
            }
            if (FinderPatternFinder.foundPatternCross(stateCount)) {
                const confirmed: boolean = this.handlePossibleCenter(stateCount, i, maxJ, pureBarcode);
                if (confirmed === true) {
                    iSkip = stateCount[0];
                    if (this.hasSkipped) {
                        // Found a third one
                        done = this.haveMultiplyConfirmedCenters();
                    }
                }
            }
        }

        const patternInfo: FinderPattern[] = this.selectBestPatterns();
        ResultPoint.orderBestPatterns(patternInfo);

        return new FinderPatternInfo(patternInfo);
    }

    /**
     * Given a count of black/white/black/white/black pixels just seen and an end position,
     * figures the location of the center of this run.
     */
    private static centerFromEnd(stateCount: Int32Array, end: number /*int*/): number/*float*/ {
        return (end - stateCount[4] - stateCount[3]) - stateCount[2] / 2.0;
    }

    /**
     * @param stateCount count of black/white/black/white/black pixels just read
     * @return true iff the proportions of the counts is close enough to the 1/1/3/1/1 ratios
     *         used by finder patterns to be considered a match
     */
    protected static foundPatternCross(stateCount: Int32Array): boolean {
        let totalModuleSize = 0;
        for (let i = 0; i < 5; i++) {
            const count = stateCount[i];
            if (count === 0) {
                return false;
            }
            totalModuleSize += count;
        }
        if (totalModuleSize < 7) {
            return false;
        }
        const moduleSize: number /*float*/ = totalModuleSize / 7.0;
        const maxVariance: number /*float*/ = moduleSize / 2.0;
        // Allow less than 50% variance from 1-1-3-1-1 proportions
        return Math.abs(moduleSize - stateCount[0]) < maxVariance &&
            Math.abs(moduleSize - stateCount[1]) < maxVariance &&
            Math.abs(3.0 * moduleSize - stateCount[2]) < 3 * maxVariance &&
            Math.abs(moduleSize - stateCount[3]) < maxVariance &&
            Math.abs(moduleSize - stateCount[4]) < maxVariance;
    }

    private getCrossCheckStateCount(): Int32Array {
        const crossCheckStateCount = this.crossCheckStateCount;
        crossCheckStateCount[0] = 0;
        crossCheckStateCount[1] = 0;
        crossCheckStateCount[2] = 0;
        crossCheckStateCount[3] = 0;
        crossCheckStateCount[4] = 0;
        return crossCheckStateCount;
    }

    /**
     * After a vertical and horizontal scan finds a potential finder pattern, this method
     * "cross-cross-cross-checks" by scanning down diagonally through the center of the possible
     * finder pattern to see if the same proportion is detected.
     *
     * @param startI row where a finder pattern was detected
     * @param centerJ center of the section that appears to cross a finder pattern
     * @param maxCount maximum reasonable number of modules that should be
     *  observed in any reading state, based on the results of the horizontal scan
     * @param originalStateCountTotal The original state count total.
     * @return true if proportions are withing expected limits
     */
    private crossCheckDiagonal(startI: number /*int*/, centerJ: number /*int*/, maxCount: number /*int*/, originalStateCountTotal: number /*int*/): boolean {
        const stateCount: Int32Array = this.getCrossCheckStateCount();

        // Start counting up, left from center finding black center mass
        let i = 0;
        const image = this.image;
        while (startI >= i && centerJ >= i && image.get(centerJ - i, startI - i)) {
            stateCount[2]++;
            i++;
        }

        if (startI < i || centerJ < i) {
            return false;
        }

        // Continue up, left finding white space
        while (startI >= i && centerJ >= i && !image.get(centerJ - i, startI - i) &&
            stateCount[1] <= maxCount) {
            stateCount[1]++;
            i++;
        }

        // If already too many modules in this state or ran off the edge:
        if (startI < i || centerJ < i || stateCount[1] > maxCount) {
            return false;
        }

        // Continue up, left finding black border
        while (startI >= i && centerJ >= i && image.get(centerJ - i, startI - i) &&
            stateCount[0] <= maxCount) {
            stateCount[0]++;
            i++;
        }
        if (stateCount[0] > maxCount) {
            return false;
        }

        const maxI = image.getHeight();
        const maxJ = image.getWidth();

        // Now also count down, right from center
        i = 1;
        while (startI + i < maxI && centerJ + i < maxJ && image.get(centerJ + i, startI + i)) {
            stateCount[2]++;
            i++;
        }

        // Ran off the edge?
        if (startI + i >= maxI || centerJ + i >= maxJ) {
            return false;
        }

        while (startI + i < maxI && centerJ + i < maxJ && !image.get(centerJ + i, startI + i) &&
            stateCount[3] < maxCount) {
            stateCount[3]++;
            i++;
        }

        if (startI + i >= maxI || centerJ + i >= maxJ || stateCount[3] >= maxCount) {
            return false;
        }

        while (startI + i < maxI && centerJ + i < maxJ && image.get(centerJ + i, startI + i) &&
            stateCount[4] < maxCount) {
            stateCount[4]++;
            i++;
        }

        if (stateCount[4] >= maxCount) {
            return false;
        }

        // If we found a finder-pattern-like section, but its size is more than 100% different than
        // the original, assume it's a false positive
        const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];
        return Math.abs(stateCountTotal - originalStateCountTotal) < 2 * originalStateCountTotal &&
            FinderPatternFinder.foundPatternCross(stateCount);
    }

    /**
     * <p>After a horizontal scan finds a potential finder pattern, this method
     * "cross-checks" by scanning down vertically through the center of the possible
     * finder pattern to see if the same proportion is detected.</p>
     *
     * @param startI row where a finder pattern was detected
     * @param centerJ center of the section that appears to cross a finder pattern
     * @param maxCount maximum reasonable number of modules that should be
     * observed in any reading state, based on the results of the horizontal scan
     * @return vertical center of finder pattern, or {@link Float#NaN} if not found
     */
    private crossCheckVertical(startI: number /*int*/, centerJ: number /*int*/, maxCount: number /*int*/,
        originalStateCountTotal: number /*int*/): number/*float*/ {
        const image: BitMatrix = this.image;

        const maxI = image.getHeight();
        const stateCount: Int32Array = this.getCrossCheckStateCount();

        // Start counting up from center
        let i = startI;
        while (i >= 0 && image.get(centerJ, i)) {
            stateCount[2]++;
            i--;
        }
        if (i < 0) {
            return NaN;
        }
        while (i >= 0 && !image.get(centerJ, i) && stateCount[1] <= maxCount) {
            stateCount[1]++;
            i--;
        }
        // If already too many modules in this state or ran off the edge:
        if (i < 0 || stateCount[1] > maxCount) {
            return NaN;
        }
        while (i >= 0 && image.get(centerJ, i) && stateCount[0] <= maxCount) {
            stateCount[0]++;
            i--;
        }
        if (stateCount[0] > maxCount) {
            return NaN;
        }

        // Now also count down from center
        i = startI + 1;
        while (i < maxI && image.get(centerJ, i)) {
            stateCount[2]++;
            i++;
        }
        if (i === maxI) {
            return NaN;
        }
        while (i < maxI && !image.get(centerJ, i) && stateCount[3] < maxCount) {
            stateCount[3]++;
            i++;
        }
        if (i === maxI || stateCount[3] >= maxCount) {
            return NaN;
        }
        while (i < maxI && image.get(centerJ, i) && stateCount[4] < maxCount) {
            stateCount[4]++;
            i++;
        }
        if (stateCount[4] >= maxCount) {
            return NaN;
        }

        // If we found a finder-pattern-like section, but its size is more than 40% different than
        // the original, assume it's a false positive
        const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
            stateCount[4];
        if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal) {
            return NaN;
        }

        return FinderPatternFinder.foundPatternCross(stateCount) ? FinderPatternFinder.centerFromEnd(stateCount, i) : NaN;
    }

    /**
     * <p>Like {@link #crossCheckVertical(int, int, int, int)}, and in fact is basically identical,
     * except it reads horizontally instead of vertically. This is used to cross-cross
     * check a vertical cross check and locate the real center of the alignment pattern.</p>
     */
    private crossCheckHorizontal(startJ: number /*int*/, centerI: number /*int*/, maxCount: number /*int*/,
        originalStateCountTotal: number /*int*/): number/*float*/ {
        const image: BitMatrix = this.image;

        const maxJ = image.getWidth();
        const stateCount: Int32Array = this.getCrossCheckStateCount();

        let j = startJ;
        while (j >= 0 && image.get(j, centerI)) {
            stateCount[2]++;
            j--;
        }
        if (j < 0) {
            return NaN;
        }
        while (j >= 0 && !image.get(j, centerI) && stateCount[1] <= maxCount) {
            stateCount[1]++;
            j--;
        }
        if (j < 0 || stateCount[1] > maxCount) {
            return NaN;
        }
        while (j >= 0 && image.get(j, centerI) && stateCount[0] <= maxCount) {
            stateCount[0]++;
            j--;
        }
        if (stateCount[0] > maxCount) {
            return NaN;
        }

        j = startJ + 1;
        while (j < maxJ && image.get(j, centerI)) {
            stateCount[2]++;
            j++;
        }
        if (j === maxJ) {
            return NaN;
        }
        while (j < maxJ && !image.get(j, centerI) && stateCount[3] < maxCount) {
            stateCount[3]++;
            j++;
        }
        if (j === maxJ || stateCount[3] >= maxCount) {
            return NaN;
        }
        while (j < maxJ && image.get(j, centerI) && stateCount[4] < maxCount) {
            stateCount[4]++;
            j++;
        }
        if (stateCount[4] >= maxCount) {
            return NaN;
        }

        // If we found a finder-pattern-like section, but its size is significantly different than
        // the original, assume it's a false positive
        const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
            stateCount[4];
        if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {
            return NaN;
        }

        return FinderPatternFinder.foundPatternCross(stateCount) ? FinderPatternFinder.centerFromEnd(stateCount, j) : NaN;
    }

    /**
     * <p>This is called when a horizontal scan finds a possible alignment pattern. It will
     * cross check with a vertical scan, and if successful, will, ah, cross-cross-check
     * with another horizontal scan. This is needed primarily to locate the real horizontal
     * center of the pattern in cases of extreme skew.
     * And then we cross-cross-cross check with another diagonal scan.</p>
     *
     * <p>If that succeeds the finder pattern location is added to a list that tracks
     * the number of times each location has been nearly-matched as a finder pattern.
     * Each additional find is more evidence that the location is in fact a finder
     * pattern center
     *
     * @param stateCount reading state module counts from horizontal scan
     * @param i row where finder pattern may be found
     * @param j end of possible finder pattern in row
     * @param pureBarcode true if in "pure barcode" mode
     * @return true if a finder pattern candidate was found this time
     */
    protected handlePossibleCenter(stateCount: Int32Array, i: number /*int*/, j: number /*int*/, pureBarcode: boolean): boolean {
        const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
            stateCount[4];
        let centerJ: number /*float*/ = FinderPatternFinder.centerFromEnd(stateCount, j);
        let centerI: number /*float*/ = this.crossCheckVertical(i, /*(int) */Math.floor(centerJ), stateCount[2], stateCountTotal);
        if (!isNaN(centerI)) {
            // Re-cross check
            centerJ = this.crossCheckHorizontal(/*(int) */Math.floor(centerJ), /*(int) */Math.floor(centerI), stateCount[2], stateCountTotal);
            if (!isNaN(centerJ) &&
                (!pureBarcode || this.crossCheckDiagonal(/*(int) */Math.floor(centerI), /*(int) */Math.floor(centerJ), stateCount[2], stateCountTotal))) {
                const estimatedModuleSize: number /*float*/ = stateCountTotal / 7.0;
                let found: boolean = false;
                const possibleCenters = this.possibleCenters;
                for (let index = 0, length = possibleCenters.length; index < length; index++) {
                    const center: FinderPattern = possibleCenters[index];
                    // Look for about the same center and module size:
                    if (center.aboutEquals(estimatedModuleSize, centerI, centerJ)) {
                        possibleCenters[index] = center.combineEstimate(centerI, centerJ, estimatedModuleSize);
                        found = true;
                        break;
                    }
                }
                if (!found) {
                    const point: FinderPattern = new FinderPattern(centerJ, centerI, estimatedModuleSize);
                    possibleCenters.push(point);
                    if (this.resultPointCallback !== null && this.resultPointCallback !== undefined) {
                        this.resultPointCallback.foundPossibleResultPoint(point);
                    }
                }
                return true;
            }
        }
        return false;
    }

    /**
     * @return number of rows we could safely skip during scanning, based on the first
     *         two finder patterns that have been located. In some cases their position will
     *         allow us to infer that the third pattern must lie below a certain point farther
     *         down in the image.
     */
    private findRowSkip(): number /*int*/ {
        const max = this.possibleCenters.length;
        if (max <= 1) {
            return 0;
        }
        let firstConfirmedCenter: ResultPoint = null;
        for (const center of this.possibleCenters) {
            if (center.getCount() >= FinderPatternFinder.CENTER_QUORUM) {
                if (firstConfirmedCenter == null) {
                    firstConfirmedCenter = center;
                } else {
                    // We have two confirmed centers
                    // How far down can we skip before resuming looking for the next
                    // pattern? In the worst case, only the difference between the
                    // difference in the x / y coordinates of the two centers.
                    // This is the case where you find top left last.
                    this.hasSkipped = true;
                    return /*(int) */Math.floor((Math.abs(firstConfirmedCenter.getX() - center.getX()) -
                        Math.abs(firstConfirmedCenter.getY() - center.getY())) / 2);
                }
            }
        }
        return 0;
    }

    /**
     * @return true iff we have found at least 3 finder patterns that have been detected
     *         at least {@link #CENTER_QUORUM} times each, and, the estimated module size of the
     *         candidates is "pretty similar"
     */
    private haveMultiplyConfirmedCenters(): boolean {
        let confirmedCount = 0;
        let totalModuleSize: number /*float*/ = 0.0;
        const max = this.possibleCenters.length;
        for (const pattern of this.possibleCenters) {
            if (pattern.getCount() >= FinderPatternFinder.CENTER_QUORUM) {
                confirmedCount++;
                totalModuleSize += pattern.getEstimatedModuleSize();
            }
        }
        if (confirmedCount < 3) {
            return false;
        }
        // OK, we have at least 3 confirmed centers, but, it's possible that one is a "false positive"
        // and that we need to keep looking. We detect this by asking if the estimated module sizes
        // vary too much. We arbitrarily say that when the total deviation from average exceeds
        // 5% of the total module size estimates, it's too much.
        const average: number /*float*/ = totalModuleSize / max;
        let totalDeviation: number /*float*/ = 0.0;
        for (const pattern of this.possibleCenters) {
            totalDeviation += Math.abs(pattern.getEstimatedModuleSize() - average);
        }
        return totalDeviation <= 0.05 * totalModuleSize;
    }

    /**
     * @return the 3 best {@link FinderPattern}s from our list of candidates. The "best" are
     *         those that have been detected at least {@link #CENTER_QUORUM} times, and whose module
     *         size differs from the average among those patterns the least
     * @throws NotFoundException if 3 such finder patterns do not exist
     */
    private selectBestPatterns(): FinderPattern[] /*throws NotFoundException */ {

        const startSize = this.possibleCenters.length;
        if (startSize < 3) {
            // Couldn't find enough finder patterns
            throw new Exception(Exception.NotFoundException);
        }

        const possibleCenters = this.possibleCenters;

        let average: number; /*float*/
        // Filter outlier possibilities whose module size is too different
        if (startSize > 3) {
            // But we can only afford to do so if we have at least 4 possibilities to choose from
            let totalModuleSize: number /*float*/ = 0.0;
            let square: number /*float*/ = 0.0;
            for (const center of this.possibleCenters) {
                const size: number /*float*/ = center.getEstimatedModuleSize();
                totalModuleSize += size;
                square += size * size;
            }
            average = totalModuleSize / startSize;
            let stdDev: number /*float*/ = /*(float) */Math.sqrt(square / startSize - average * average);

            possibleCenters.sort(
                /**
                 * <p>Orders by furthest from average</p>
                 */
                // FurthestFromAverageComparator implements Comparator<FinderPattern>
                (center1: FinderPattern, center2: FinderPattern) => {
                    const dA: number /*float*/ = Math.abs(center2.getEstimatedModuleSize() - average);
                    const dB: number /*float*/ = Math.abs(center1.getEstimatedModuleSize() - average);
                    return dA < dB ? -1 : dA > dB ? 1 : 0;
                });

            const limit: number /*float*/ = Math.max(0.2 * average, stdDev);

            for (let i = 0; i < possibleCenters.length && possibleCenters.length > 3; i++) {
                const pattern: FinderPattern = possibleCenters[i];
                if (Math.abs(pattern.getEstimatedModuleSize() - average) > limit) {
                    possibleCenters.splice(i, 1);
                    i--;
                }
            }
        }

        if (possibleCenters.length > 3) {
            // Throw away all but those first size candidate points we found.

            let totalModuleSize: number /*float*/ = 0.0;
            for (const possibleCenter of possibleCenters) {
                totalModuleSize += possibleCenter.getEstimatedModuleSize();
            }

            average = totalModuleSize / possibleCenters.length;

            possibleCenters.sort(
                /**
                 * <p>Orders by {@link FinderPattern#getCount()}, descending.</p>
                 */
                // CenterComparator implements Comparator<FinderPattern>
                (center1: FinderPattern, center2: FinderPattern) => {
                    if (center2.getCount() === center1.getCount()) {
                        const dA: number /*float*/ = Math.abs(center2.getEstimatedModuleSize() - average);
                        const dB: number /*float*/ = Math.abs(center1.getEstimatedModuleSize() - average);
                        return dA < dB ? 1 : dA > dB ? -1 : 0;
                    } else {
                        return center2.getCount() - center1.getCount();
                    }
                });

            possibleCenters.splice(3); // this is not realy necessary as we only return first 3 anyway
        }

        return [
            possibleCenters[0],
            possibleCenters[1],
            possibleCenters[2]
        ];
    }
}