import os
import tqdm
import pickle
import numpy as np
from scipy.io import loadmat
import cv2 as cv


def get_gt_boxes(gt_dir):
    """ gt dir: (wider_face_val.mat, wider_easy_val.mat, wider_medium_val.mat, wider_hard_val.mat)"""

    gt_mat = loadmat(os.path.join(gt_dir, 'wider_face_val.mat'))
    hard_mat = loadmat(os.path.join(gt_dir, 'wider_hard_val.mat'))
    medium_mat = loadmat(os.path.join(gt_dir, 'wider_medium_val.mat'))
    easy_mat = loadmat(os.path.join(gt_dir, 'wider_easy_val.mat'))

    facebox_list = gt_mat['face_bbx_list']
    event_list = gt_mat['event_list']
    file_list = gt_mat['file_list']

    hard_gt_list = hard_mat['gt_list']
    medium_gt_list = medium_mat['gt_list']
    easy_gt_list = easy_mat['gt_list']

    return facebox_list, event_list, file_list, hard_gt_list, medium_gt_list, easy_gt_list


def get_gt_boxes_from_txt(gt_path, cache_dir):
    cache_file = os.path.join(cache_dir, 'gt_cache.pkl')
    if os.path.exists(cache_file):
        f = open(cache_file, 'rb')
        boxes = pickle.load(f)
        f.close()
        return boxes

    f = open(gt_path, 'r')
    state = 0
    lines = f.readlines()
    lines = list(map(lambda x: x.rstrip('\r\n'), lines))
    boxes = {}
    print(len(lines))
    f.close()
    current_boxes = []
    current_name = None
    for line in lines:
        if state == 0 and '--' in line:
            state = 1
            current_name = line
            continue
        if state == 1:
            state = 2
            continue

        if state == 2 and '--' in line:
            state = 1
            boxes[current_name] = np.array(current_boxes).astype('float32')
            current_name = line
            current_boxes = []
            continue

        if state == 2:
            box = [float(x) for x in line.split(' ')[:4]]
            current_boxes.append(box)
            continue

    f = open(cache_file, 'wb')
    pickle.dump(boxes, f)
    f.close()
    return boxes


def norm_score(pred):
    """ norm score
    pred {key: [[x1,y1,x2,y2,s]]}
    """

    max_score = 0
    min_score = 1

    for _, k in pred.items():
        for _, v in k.items():
            if len(v) == 0:
                continue
            _min = np.min(v[:, -1])
            _max = np.max(v[:, -1])
            max_score = max(_max, max_score)
            min_score = min(_min, min_score)

    diff = max_score - min_score
    for _, k in pred.items():
        for _, v in k.items():
            if len(v) == 0:
                continue
            v[:, -1] = (v[:, -1] - min_score) / diff


def bbox_overlaps(a, b):
    """
    return iou of a and b, numpy version for data augenmentation
    """
    lt = np.maximum(a[:, np.newaxis, 0:2], b[:, 0:2])
    rb = np.minimum(a[:, np.newaxis, 2:4], b[:, 2:4])

    area_i = np.prod(rb - lt + 1, axis=2) * (lt < rb).all(axis=2)
    area_a = np.prod(a[:, 2:4] - a[:, 0:2] + 1, axis=1)
    area_b = np.prod(b[:, 2:4] - b[:, 0:2] + 1, axis=1)
    return area_i / (area_a[:, np.newaxis] + area_b - area_i)


def image_eval(pred, gt, ignore, iou_thresh):
    """ single image evaluation
    pred: Nx5
    gt: Nx4
    ignore:
    """

    _pred = pred.copy()
    _gt = gt.copy()
    pred_recall = np.zeros(_pred.shape[0])
    recall_list = np.zeros(_gt.shape[0])
    proposal_list = np.ones(_pred.shape[0])

    _pred[:, 2] = _pred[:, 2] + _pred[:, 0]
    _pred[:, 3] = _pred[:, 3] + _pred[:, 1]
    _gt[:, 2] = _gt[:, 2] + _gt[:, 0]
    _gt[:, 3] = _gt[:, 3] + _gt[:, 1]

    overlaps = bbox_overlaps(_pred[:, :4], _gt)

    for h in range(_pred.shape[0]):

        gt_overlap = overlaps[h]
        max_overlap, max_idx = gt_overlap.max(), gt_overlap.argmax()
        if max_overlap >= iou_thresh:
            if ignore[max_idx] == 0:
                recall_list[max_idx] = -1
                proposal_list[h] = -1
            elif recall_list[max_idx] == 0:
                recall_list[max_idx] = 1

        r_keep_index = np.where(recall_list == 1)[0]
        pred_recall[h] = len(r_keep_index)
    return pred_recall, proposal_list


def img_pr_info(thresh_num, pred_info, proposal_list, pred_recall):
    pr_info = np.zeros((thresh_num, 2)).astype('float')
    for t in range(thresh_num):

        thresh = 1 - (t + 1) / thresh_num
        r_index = np.where(pred_info[:, 4] >= thresh)[0]
        if len(r_index) == 0:
            pr_info[t, 0] = 0
            pr_info[t, 1] = 0
        else:
            r_index = r_index[-1]
            p_index = np.where(proposal_list[:r_index + 1] == 1)[0]
            pr_info[t, 0] = len(p_index)
            pr_info[t, 1] = pred_recall[r_index]
    return pr_info


def dataset_pr_info(thresh_num, pr_curve, count_face):
    _pr_curve = np.zeros((thresh_num, 2))
    for i in range(thresh_num):
        _pr_curve[i, 0] = pr_curve[i, 1] / pr_curve[i, 0]
        _pr_curve[i, 1] = pr_curve[i, 1] / count_face
    return _pr_curve


def voc_ap(rec, prec):
    # correct AP calculation
    # first append sentinel values at the end
    mrec = np.concatenate(([0.], rec, [1.]))
    mpre = np.concatenate(([0.], prec, [0.]))

    # compute the precision envelope
    for i in range(mpre.size - 1, 0, -1):
        mpre[i - 1] = np.maximum(mpre[i - 1], mpre[i])

    # to calculate area under PR curve, look for points
    # where X axis (recall) changes value
    i = np.where(mrec[1:] != mrec[:-1])[0]

    # and sum (\Delta recall) * prec
    ap = np.sum((mrec[i + 1] - mrec[i]) * mpre[i + 1])
    return ap


def evaluation(pred, gt_path, iou_thresh=0.5):
    norm_score(pred)
    facebox_list, event_list, file_list, hard_gt_list, medium_gt_list, easy_gt_list = get_gt_boxes(gt_path)
    event_num = len(event_list)
    thresh_num = 1000
    settings = ['easy', 'medium', 'hard']
    setting_gts = [easy_gt_list, medium_gt_list, hard_gt_list]
    aps = []
    for setting_id in range(3):
        # different setting
        gt_list = setting_gts[setting_id]
        count_face = 0
        pr_curve = np.zeros((thresh_num, 2)).astype('float')
        # [hard, medium, easy]
        pbar = tqdm.tqdm(range(event_num))
        for i in pbar:
            pbar.set_description('Processing {}'.format(settings[setting_id]))
            event_name = str(event_list[i][0][0])
            img_list = file_list[i][0]
            pred_list = pred[event_name]
            sub_gt_list = gt_list[i][0]
            # img_pr_info_list = np.zeros((len(img_list), thresh_num, 2))
            gt_bbx_list = facebox_list[i][0]

            for j in range(len(img_list)):
                pred_info = pred_list[str(img_list[j][0][0])]

                gt_boxes = gt_bbx_list[j][0].astype('float')
                keep_index = sub_gt_list[j][0]
                count_face += len(keep_index)

                if len(gt_boxes) == 0 or len(pred_info) == 0:
                    continue
                ignore = np.zeros(gt_boxes.shape[0])
                if len(keep_index) != 0:
                    ignore[keep_index - 1] = 1
                pred_recall, proposal_list = image_eval(pred_info, gt_boxes, ignore, iou_thresh)

                _img_pr_info = img_pr_info(thresh_num, pred_info, proposal_list, pred_recall)

                pr_curve += _img_pr_info
        pr_curve = dataset_pr_info(thresh_num, pr_curve, count_face)

        propose = pr_curve[:, 0]
        recall = pr_curve[:, 1]

        ap = voc_ap(recall, propose)
        aps.append(ap)
    return aps


class WIDERFace:
    def __init__(self, root, split='val'):
        self.aps = []
        self.widerface_root = root
        self._split = split

        self.widerface_img_paths = {
            'val': os.path.join(self.widerface_root, 'WIDER_val', 'images'),
            'test': os.path.join(self.widerface_root, 'WIDER_test', 'images')
        }

        self.widerface_split_fpaths = {
            'val': os.path.join(self.widerface_root, 'wider_face_split', 'wider_face_val.mat'),
            'test': os.path.join(self.widerface_root, 'wider_face_split', 'wider_face_test.mat')
        }
        self.img_list, self.num_img = self.load_list()

    @property
    def name(self):
        return self.__class__.__name__

    def load_list(self):
        n_imgs = 0
        flist = []

        split_fpath = self.widerface_split_fpaths[self._split]
        img_path = self.widerface_img_paths[self._split]

        anno_data = loadmat(split_fpath)
        event_list = anno_data.get('event_list')
        file_list = anno_data.get('file_list')

        for event_idx, event in enumerate(event_list):
            event_name = event[0][0]
            for f_idx, f in enumerate(file_list[event_idx][0]):
                f_name = f[0][0]
                f_path = os.path.join(img_path, event_name, f_name + '.jpg')
                flist.append(f_path)
                n_imgs += 1

        return flist, n_imgs

    def __getitem__(self, index):
        img = cv.imread(self.img_list[index])
        event, name = self.img_list[index].split(os.sep)[-2:]
        return event, name, img

    def eval(self, model):
        results_list = dict()
        pbar = tqdm.tqdm(self)
        pbar.set_description_str("Evaluating {} with {} val set".format(model.name, self.name))
        # forward
        for event_name, img_name, img in pbar:
            img_shape = [img.shape[1], img.shape[0]]
            model.setInputSize(img_shape)
            det = model.infer(img)

            if not results_list.get(event_name):
                results_list[event_name] = dict()

            if det is None:
                det = np.array([[10, 10, 20, 20, 0.002]])
            else:
                det = np.append(np.around(det[:, :4], 1), np.around(det[:, -1], 3).reshape(-1, 1), axis=1)

            results_list[event_name][img_name.rstrip('.jpg')] = det

        self.aps = evaluation(results_list, os.path.join(self.widerface_root, 'eval_tools', 'ground_truth'))

    def print_result(self):
        print("==================== Results ====================")
        print("Easy   Val AP: {}".format(self.aps[0]))
        print("Medium Val AP: {}".format(self.aps[1]))
        print("Hard   Val AP: {}".format(self.aps[2]))
        print("=================================================")