# Ultralytics YOLO 🚀, AGPL-3.0 license

import copy

import cv2
import numpy as np

from ultralytics.yolo.utils import LOGGER


class GMC:

    def __init__(self, method='sparseOptFlow', downscale=2, verbose=None):
        """Initialize a video tracker with specified parameters."""
        super().__init__()

        self.method = method
        self.downscale = max(1, int(downscale))

        if self.method == 'orb':
            self.detector = cv2.FastFeatureDetector_create(20)
            self.extractor = cv2.ORB_create()
            self.matcher = cv2.BFMatcher(cv2.NORM_HAMMING)

        elif self.method == 'sift':
            self.detector = cv2.SIFT_create(nOctaveLayers=3, contrastThreshold=0.02, edgeThreshold=20)
            self.extractor = cv2.SIFT_create(nOctaveLayers=3, contrastThreshold=0.02, edgeThreshold=20)
            self.matcher = cv2.BFMatcher(cv2.NORM_L2)

        elif self.method == 'ecc':
            number_of_iterations = 5000
            termination_eps = 1e-6
            self.warp_mode = cv2.MOTION_EUCLIDEAN
            self.criteria = (cv2.TERM_CRITERIA_EPS | cv2.TERM_CRITERIA_COUNT, number_of_iterations, termination_eps)

        elif self.method == 'sparseOptFlow':
            self.feature_params = dict(maxCorners=1000,
                                       qualityLevel=0.01,
                                       minDistance=1,
                                       blockSize=3,
                                       useHarrisDetector=False,
                                       k=0.04)
            # self.gmc_file = open('GMC_results.txt', 'w')

        elif self.method in ['file', 'files']:
            seqName = verbose[0]
            ablation = verbose[1]
            if ablation:
                filePath = r'tracker/GMC_files/MOT17_ablation'
            else:
                filePath = r'tracker/GMC_files/MOTChallenge'

            if '-FRCNN' in seqName:
                seqName = seqName[:-6]
            elif '-DPM' in seqName or '-SDP' in seqName:
                seqName = seqName[:-4]
            self.gmcFile = open(f'{filePath}/GMC-{seqName}.txt')

            if self.gmcFile is None:
                raise ValueError(f'Error: Unable to open GMC file in directory:{filePath}')
        elif self.method in ['none', 'None']:
            self.method = 'none'
        else:
            raise ValueError(f'Error: Unknown CMC method:{method}')

        self.prevFrame = None
        self.prevKeyPoints = None
        self.prevDescriptors = None

        self.initializedFirstFrame = False

    def apply(self, raw_frame, detections=None):
        """Apply object detection on a raw frame using specified method."""
        if self.method in ['orb', 'sift']:
            return self.applyFeatures(raw_frame, detections)
        elif self.method == 'ecc':
            return self.applyEcc(raw_frame, detections)
        elif self.method == 'sparseOptFlow':
            return self.applySparseOptFlow(raw_frame, detections)
        elif self.method == 'file':
            return self.applyFile(raw_frame, detections)
        elif self.method == 'none':
            return np.eye(2, 3)
        else:
            return np.eye(2, 3)

    def applyEcc(self, raw_frame, detections=None):
        """Initialize."""
        height, width, _ = raw_frame.shape
        frame = cv2.cvtColor(raw_frame, cv2.COLOR_BGR2GRAY)
        H = np.eye(2, 3, dtype=np.float32)

        # Downscale image (TODO: consider using pyramids)
        if self.downscale > 1.0:
            frame = cv2.GaussianBlur(frame, (3, 3), 1.5)
            frame = cv2.resize(frame, (width // self.downscale, height // self.downscale))
            width = width // self.downscale
            height = height // self.downscale

        # Handle first frame
        if not self.initializedFirstFrame:
            # Initialize data
            self.prevFrame = frame.copy()

            # Initialization done
            self.initializedFirstFrame = True

            return H

        # Run the ECC algorithm. The results are stored in warp_matrix.
        # (cc, H) = cv2.findTransformECC(self.prevFrame, frame, H, self.warp_mode, self.criteria)
        try:
            (cc, H) = cv2.findTransformECC(self.prevFrame, frame, H, self.warp_mode, self.criteria, None, 1)
        except Exception as e:
            LOGGER.warning(f'WARNING: find transform failed. Set warp as identity {e}')

        return H

    def applyFeatures(self, raw_frame, detections=None):
        """Initialize."""
        height, width, _ = raw_frame.shape
        frame = cv2.cvtColor(raw_frame, cv2.COLOR_BGR2GRAY)
        H = np.eye(2, 3)

        # Downscale image (TODO: consider using pyramids)
        if self.downscale > 1.0:
            # frame = cv2.GaussianBlur(frame, (3, 3), 1.5)
            frame = cv2.resize(frame, (width // self.downscale, height // self.downscale))
            width = width // self.downscale
            height = height // self.downscale

        # Find the keypoints
        mask = np.zeros_like(frame)
        # mask[int(0.05 * height): int(0.95 * height), int(0.05 * width): int(0.95 * width)] = 255
        mask[int(0.02 * height):int(0.98 * height), int(0.02 * width):int(0.98 * width)] = 255
        if detections is not None:
            for det in detections:
                tlbr = (det[:4] / self.downscale).astype(np.int_)
                mask[tlbr[1]:tlbr[3], tlbr[0]:tlbr[2]] = 0

        keypoints = self.detector.detect(frame, mask)

        # Compute the descriptors
        keypoints, descriptors = self.extractor.compute(frame, keypoints)

        # Handle first frame
        if not self.initializedFirstFrame:
            # Initialize data
            self.prevFrame = frame.copy()
            self.prevKeyPoints = copy.copy(keypoints)
            self.prevDescriptors = copy.copy(descriptors)

            # Initialization done
            self.initializedFirstFrame = True

            return H

        # Match descriptors.
        knnMatches = self.matcher.knnMatch(self.prevDescriptors, descriptors, 2)

        # Filtered matches based on smallest spatial distance
        matches = []
        spatialDistances = []

        maxSpatialDistance = 0.25 * np.array([width, height])

        # Handle empty matches case
        if len(knnMatches) == 0:
            # Store to next iteration
            self.prevFrame = frame.copy()
            self.prevKeyPoints = copy.copy(keypoints)
            self.prevDescriptors = copy.copy(descriptors)

            return H

        for m, n in knnMatches:
            if m.distance < 0.9 * n.distance:
                prevKeyPointLocation = self.prevKeyPoints[m.queryIdx].pt
                currKeyPointLocation = keypoints[m.trainIdx].pt

                spatialDistance = (prevKeyPointLocation[0] - currKeyPointLocation[0],
                                   prevKeyPointLocation[1] - currKeyPointLocation[1])

                if (np.abs(spatialDistance[0]) < maxSpatialDistance[0]) and \
                        (np.abs(spatialDistance[1]) < maxSpatialDistance[1]):
                    spatialDistances.append(spatialDistance)
                    matches.append(m)

        meanSpatialDistances = np.mean(spatialDistances, 0)
        stdSpatialDistances = np.std(spatialDistances, 0)

        inliers = (spatialDistances - meanSpatialDistances) < 2.5 * stdSpatialDistances

        goodMatches = []
        prevPoints = []
        currPoints = []
        for i in range(len(matches)):
            if inliers[i, 0] and inliers[i, 1]:
                goodMatches.append(matches[i])
                prevPoints.append(self.prevKeyPoints[matches[i].queryIdx].pt)
                currPoints.append(keypoints[matches[i].trainIdx].pt)

        prevPoints = np.array(prevPoints)
        currPoints = np.array(currPoints)

        # Draw the keypoint matches on the output image
        # if False:
        #     import matplotlib.pyplot as plt
        #     matches_img = np.hstack((self.prevFrame, frame))
        #     matches_img = cv2.cvtColor(matches_img, cv2.COLOR_GRAY2BGR)
        #     W = np.size(self.prevFrame, 1)
        #     for m in goodMatches:
        #         prev_pt = np.array(self.prevKeyPoints[m.queryIdx].pt, dtype=np.int_)
        #         curr_pt = np.array(keypoints[m.trainIdx].pt, dtype=np.int_)
        #         curr_pt[0] += W
        #         color = np.random.randint(0, 255, 3)
        #         color = (int(color[0]), int(color[1]), int(color[2]))
        #
        #         matches_img = cv2.line(matches_img, prev_pt, curr_pt, tuple(color), 1, cv2.LINE_AA)
        #         matches_img = cv2.circle(matches_img, prev_pt, 2, tuple(color), -1)
        #         matches_img = cv2.circle(matches_img, curr_pt, 2, tuple(color), -1)
        #
        #     plt.figure()
        #     plt.imshow(matches_img)
        #     plt.show()

        # Find rigid matrix
        if (np.size(prevPoints, 0) > 4) and (np.size(prevPoints, 0) == np.size(prevPoints, 0)):
            H, inliers = cv2.estimateAffinePartial2D(prevPoints, currPoints, cv2.RANSAC)

            # Handle downscale
            if self.downscale > 1.0:
                H[0, 2] *= self.downscale
                H[1, 2] *= self.downscale
        else:
            LOGGER.warning('WARNING: not enough matching points')

        # Store to next iteration
        self.prevFrame = frame.copy()
        self.prevKeyPoints = copy.copy(keypoints)
        self.prevDescriptors = copy.copy(descriptors)

        return H

    def applySparseOptFlow(self, raw_frame, detections=None):
        """Initialize."""
        # t0 = time.time()
        height, width, _ = raw_frame.shape
        frame = cv2.cvtColor(raw_frame, cv2.COLOR_BGR2GRAY)
        H = np.eye(2, 3)

        # Downscale image
        if self.downscale > 1.0:
            # frame = cv2.GaussianBlur(frame, (3, 3), 1.5)
            frame = cv2.resize(frame, (width // self.downscale, height // self.downscale))

        # Find the keypoints
        keypoints = cv2.goodFeaturesToTrack(frame, mask=None, **self.feature_params)

        # Handle first frame
        if not self.initializedFirstFrame:
            # Initialize data
            self.prevFrame = frame.copy()
            self.prevKeyPoints = copy.copy(keypoints)

            # Initialization done
            self.initializedFirstFrame = True

            return H

        # Find correspondences
        matchedKeypoints, status, err = cv2.calcOpticalFlowPyrLK(self.prevFrame, frame, self.prevKeyPoints, None)

        # Leave good correspondences only
        prevPoints = []
        currPoints = []

        for i in range(len(status)):
            if status[i]:
                prevPoints.append(self.prevKeyPoints[i])
                currPoints.append(matchedKeypoints[i])

        prevPoints = np.array(prevPoints)
        currPoints = np.array(currPoints)

        # Find rigid matrix
        if (np.size(prevPoints, 0) > 4) and (np.size(prevPoints, 0) == np.size(prevPoints, 0)):
            H, inliers = cv2.estimateAffinePartial2D(prevPoints, currPoints, cv2.RANSAC)

            # Handle downscale
            if self.downscale > 1.0:
                H[0, 2] *= self.downscale
                H[1, 2] *= self.downscale
        else:
            LOGGER.warning('WARNING: not enough matching points')

        # Store to next iteration
        self.prevFrame = frame.copy()
        self.prevKeyPoints = copy.copy(keypoints)

        # gmc_line = str(1000 * (time.time() - t0)) + "\t" + str(H[0, 0]) + "\t" + str(H[0, 1]) + "\t" + str(
        #     H[0, 2]) + "\t" + str(H[1, 0]) + "\t" + str(H[1, 1]) + "\t" + str(H[1, 2]) + "\n"
        # self.gmc_file.write(gmc_line)

        return H

    def applyFile(self, raw_frame, detections=None):
        """Return the homography matrix based on the GCPs in the next line of the input GMC file."""
        line = self.gmcFile.readline()
        tokens = line.split('\t')
        H = np.eye(2, 3, dtype=np.float_)
        H[0, 0] = float(tokens[1])
        H[0, 1] = float(tokens[2])
        H[0, 2] = float(tokens[3])
        H[1, 0] = float(tokens[4])
        H[1, 1] = float(tokens[5])
        H[1, 2] = float(tokens[6])

        return H
