# Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
#
# 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.

import motmetrics as mm
from pptracking.python.mot.visualize import plot_tracking
import os
import re
import cv2
import gc
import numpy as np
from sklearn import preprocessing
from sklearn.cluster import AgglomerativeClustering
import pandas as pd
from tqdm import tqdm
from functools import reduce
import warnings
warnings.filterwarnings("ignore")


def gen_restxt(output_dir_filename, map_tid, cid_tid_dict):
    pattern = re.compile(r'c(\d)_t(\d)')
    f_w = open(output_dir_filename, 'w')
    for key, res in cid_tid_dict.items():
        cid, tid = pattern.search(key).groups()
        cid = int(cid) + 1
        rects = res["rects"]
        frames = res["frames"]
        for idx, bbox in enumerate(rects):
            bbox[0][3:] -= bbox[0][1:3]
            fid = frames[idx] + 1
            rect = [max(int(x), 0) for x in bbox[0][1:]]
            if key in map_tid:
                new_tid = map_tid[key]
                f_w.write(
                    str(cid) + ' ' + str(new_tid) + ' ' + str(fid) + ' ' +
                    ' '.join(map(str, rect)) + '\n')
    print('gen_res: write file in {}'.format(output_dir_filename))
    f_w.close()


def get_mtmct_matching_results(pred_mtmct_file, secs_interval=0.5,
                               video_fps=20):
    res = np.loadtxt(pred_mtmct_file)  # 'cid, tid, fid, x1, y1, w, h, -1, -1'
    camera_ids = list(map(int, np.unique(res[:, 0])))

    res = res[:, :7]
    # each line in res: 'cid, tid, fid, x1, y1, w, h'

    camera_tids = []
    camera_results = dict()
    for c_id in camera_ids:
        camera_results[c_id] = res[res[:, 0] == c_id]
        tids = np.unique(camera_results[c_id][:, 1])
        tids = list(map(int, tids))
        camera_tids.append(tids)

    # select common tids throughout each video
    common_tids = reduce(np.intersect1d, camera_tids)

    # get mtmct matching results by cid_tid_fid_results[c_id][t_id][f_id]
    cid_tid_fid_results = dict()
    cid_tid_to_fids = dict()
    interval = int(secs_interval * video_fps)  # preferably less than 10
    for c_id in camera_ids:
        cid_tid_fid_results[c_id] = dict()
        cid_tid_to_fids[c_id] = dict()
        for t_id in common_tids:
            tid_mask = camera_results[c_id][:, 1] == t_id
            cid_tid_fid_results[c_id][t_id] = dict()

            camera_trackid_results = camera_results[c_id][tid_mask]
            fids = np.unique(camera_trackid_results[:, 2])
            fids = fids[fids % interval == 0]
            fids = list(map(int, fids))
            cid_tid_to_fids[c_id][t_id] = fids

            for f_id in fids:
                st_frame = f_id
                ed_frame = f_id + interval

                st_mask = camera_trackid_results[:, 2] >= st_frame
                ed_mask = camera_trackid_results[:, 2] < ed_frame
                frame_mask = np.logical_and(st_mask, ed_mask)
                cid_tid_fid_results[c_id][t_id][f_id] = camera_trackid_results[
                    frame_mask]

    return camera_results, cid_tid_fid_results


def save_mtmct_vis_results(camera_results, captures, output_dir):
    # camera_results: 'cid, tid, fid, x1, y1, w, h'
    camera_ids = list(camera_results.keys())

    import shutil
    save_dir = os.path.join(output_dir, 'mtmct_vis')
    if os.path.exists(save_dir):
        shutil.rmtree(save_dir)
    os.makedirs(save_dir)

    for idx, video_file in enumerate(captures):
        capture = cv2.VideoCapture(video_file)
        cid = camera_ids[idx]
        basename = os.path.basename(video_file)
        video_out_name = "vis_" + basename
        print("Start visualizing output video: {}".format(video_out_name))
        out_path = os.path.join(save_dir, video_out_name)

        # Get Video info : resolution, fps, frame count
        width = int(capture.get(cv2.CAP_PROP_FRAME_WIDTH))
        height = int(capture.get(cv2.CAP_PROP_FRAME_HEIGHT))
        fps = int(capture.get(cv2.CAP_PROP_FPS))
        frame_count = int(capture.get(cv2.CAP_PROP_FRAME_COUNT))
        fourcc = cv2.VideoWriter_fourcc(* 'mp4v')
        writer = cv2.VideoWriter(out_path, fourcc, fps, (width, height))
        frame_id = 0
        while (1):
            if frame_id % 50 == 0:
                print('frame id: ', frame_id)
            ret, frame = capture.read()
            frame_id += 1
            if not ret:
                if frame_id == 1:
                    print("video read failed!")
                break
            frame_results = camera_results[cid][camera_results[cid][:, 2] ==
                                                frame_id]
            boxes = frame_results[:, -4:]
            ids = frame_results[:, 1]
            image = plot_tracking(frame, boxes, ids, frame_id=frame_id, fps=fps)
            writer.write(image)
        writer.release()


def get_euclidean(x, y, **kwargs):
    m = x.shape[0]
    n = y.shape[0]
    distmat = (np.power(x, 2).sum(axis=1, keepdims=True).repeat(
        n, axis=1) + np.power(y, 2).sum(axis=1, keepdims=True).repeat(
            m, axis=1).T)
    distmat -= np.dot(2 * x, y.T)
    return distmat


def cosine_similarity(x, y, eps=1e-12):
    """
    Computes cosine similarity between two tensors.
    Value == 1 means the same vector
    Value == 0 means perpendicular vectors
    """
    x_n, y_n = np.linalg.norm(
        x, axis=1, keepdims=True), np.linalg.norm(
            y, axis=1, keepdims=True)
    x_norm = x / np.maximum(x_n, eps * np.ones_like(x_n))
    y_norm = y / np.maximum(y_n, eps * np.ones_like(y_n))
    sim_mt = np.dot(x_norm, y_norm.T)
    return sim_mt


def get_cosine(x, y, eps=1e-12):
    """
    Computes cosine distance between two tensors.
    The cosine distance is the inverse cosine similarity
    -> cosine_distance = abs(-cosine_distance) to make it
    similar in behaviour to euclidean distance
    """
    sim_mt = cosine_similarity(x, y, eps)
    return sim_mt


def get_dist_mat(x, y, func_name="euclidean"):
    if func_name == "cosine":
        dist_mat = get_cosine(x, y)
    elif func_name == "euclidean":
        dist_mat = get_euclidean(x, y)
    print("Using {} as distance function during evaluation".format(func_name))
    return dist_mat


def intracam_ignore(st_mask, cid_tids):
    count = len(cid_tids)
    for i in range(count):
        for j in range(count):
            if cid_tids[i][1] == cid_tids[j][1]:
                st_mask[i, j] = 0.
    return st_mask


def get_sim_matrix_new(cid_tid_dict, cid_tids):
    # Note: camera independent get_sim_matrix function,
    # which is different from the one in camera_utils.py.
    count = len(cid_tids)

    q_arr = np.array(
        [cid_tid_dict[cid_tids[i]]['mean_feat'] for i in range(count)])
    g_arr = np.array(
        [cid_tid_dict[cid_tids[i]]['mean_feat'] for i in range(count)])
    #compute distmat
    distmat = get_dist_mat(q_arr, g_arr, func_name="cosine")

    #mask the element which belongs to same video
    st_mask = np.ones((count, count), dtype=np.float32)
    st_mask = intracam_ignore(st_mask, cid_tids)

    sim_matrix = distmat * st_mask
    np.fill_diagonal(sim_matrix, 0.)
    return 1. - sim_matrix


def get_match(cluster_labels):
    cluster_dict = dict()
    cluster = list()
    for i, l in enumerate(cluster_labels):
        if l in list(cluster_dict.keys()):
            cluster_dict[l].append(i)
        else:
            cluster_dict[l] = [i]
    for idx in cluster_dict:
        cluster.append(cluster_dict[idx])
    return cluster


def get_cid_tid(cluster_labels, cid_tids):
    cluster = list()
    for labels in cluster_labels:
        cid_tid_list = list()
        for label in labels:
            cid_tid_list.append(cid_tids[label])
        cluster.append(cid_tid_list)
    return cluster


def get_labels(cid_tid_dict, cid_tids):
    #compute cost matrix between features
    cost_matrix = get_sim_matrix_new(cid_tid_dict, cid_tids)

    #cluster all the features
    cluster1 = AgglomerativeClustering(
        n_clusters=None,
        distance_threshold=0.5,
        affinity='precomputed',
        linkage='complete')
    cluster_labels1 = cluster1.fit_predict(cost_matrix)
    labels = get_match(cluster_labels1)

    sub_cluster = get_cid_tid(labels, cid_tids)
    return labels


def sub_cluster(cid_tid_dict):
    '''
    cid_tid_dict: all camera_id and track_id
    '''
    #get all keys
    cid_tids = sorted([key for key in cid_tid_dict.keys()])

    #cluster all trackid
    clu = get_labels(cid_tid_dict, cid_tids)

    #relabel every cluster groups
    new_clu = list()
    for c_list in clu:
        new_clu.append([cid_tids[c] for c in c_list])
    cid_tid_label = dict()
    for i, c_list in enumerate(new_clu):
        for c in c_list:
            cid_tid_label[c] = i + 1
    return cid_tid_label


def distill_idfeat(mot_res):
    qualities_list = mot_res["qualities"]
    feature_list = mot_res["features"]
    rects = mot_res["rects"]

    qualities_new = []
    feature_new = []
    #filter rect less than 100*20
    for idx, rect in enumerate(rects):
        conf, xmin, ymin, xmax, ymax = rect[0]
        if (xmax - xmin) * (ymax - ymin) and (xmax > xmin) > 2000:
            qualities_new.append(qualities_list[idx])
            feature_new.append(feature_list[idx])
    #take all features if available rect is less than 2
    if len(qualities_new) < 2:
        qualities_new = qualities_list
        feature_new = feature_list

    #if available frames number is more than 200, take one frame data per 20 frames
    skipf = 1
    if len(qualities_new) > 20:
        skipf = 2
    quality_skip = np.array(qualities_new[::skipf])
    feature_skip = np.array(feature_new[::skipf])

    #sort features with image qualities, take the most trustworth features
    topk_argq = np.argsort(quality_skip)[::-1]
    if (quality_skip > 0.6).sum() > 1:
        topk_feat = feature_skip[topk_argq[quality_skip > 0.6]]
    else:
        topk_feat = feature_skip[topk_argq]

    #get final features by mean or cluster, at most take five
    mean_feat = np.mean(topk_feat[:5], axis=0)
    return mean_feat


def res2dict(multi_res):
    cid_tid_dict = {}
    for cid, c_res in enumerate(multi_res):
        for tid, res in c_res.items():
            key = "c" + str(cid) + "_t" + str(tid)
            if key not in cid_tid_dict:
                cid_tid_dict[key] = res
                cid_tid_dict[key]['mean_feat'] = distill_idfeat(res)
    return cid_tid_dict


def mtmct_process(multi_res, captures, mtmct_vis=True, output_dir="output"):
    cid_tid_dict = res2dict(multi_res)
    map_tid = sub_cluster(cid_tid_dict)

    if not os.path.exists(output_dir):
        os.mkdir(output_dir)
    pred_mtmct_file = os.path.join(output_dir, 'mtmct_result.txt')
    gen_restxt(pred_mtmct_file, map_tid, cid_tid_dict)

    if mtmct_vis:
        camera_results, cid_tid_fid_res = get_mtmct_matching_results(
            pred_mtmct_file)

        save_mtmct_vis_results(camera_results, captures, output_dir=output_dir)