#  Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserve.
#
#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 numpy as np
import pandas as pd
import multiprocessing as mp
import json
import os
import math


def iou_with_anchors(anchors_min, anchors_max, box_min, box_max):
    """Compute jaccard score between a box and the anchors.
    """
    len_anchors = anchors_max - anchors_min
    int_xmin = np.maximum(anchors_min, box_min)
    int_xmax = np.minimum(anchors_max, box_max)
    inter_len = np.maximum(int_xmax - int_xmin, 0.)
    union_len = len_anchors - inter_len + box_max - box_min
    jaccard = np.divide(inter_len, union_len)
    return jaccard


def ioa_with_anchors(anchors_min, anchors_max, box_min, box_max):
    """Compute intersection between score a box and the anchors.
    """
    len_anchors = anchors_max - anchors_min
    int_xmin = np.maximum(anchors_min, box_min)
    int_xmax = np.minimum(anchors_max, box_max)
    inter_len = np.maximum(int_xmax - int_xmin, 0.)
    scores = np.divide(inter_len, len_anchors)
    return scores


def boundary_choose(score_list):
    max_score = max(score_list)
    mask_high = (score_list > max_score * 0.5)
    score_list = list(score_list)
    score_middle = np.array([0.0] + score_list + [0.0])
    score_front = np.array([0.0, 0.0] + score_list)
    score_back = np.array(score_list + [0.0, 0.0])
    mask_peak = ((score_middle > score_front) & (score_middle > score_back))
    mask_peak = mask_peak[1:-1]
    mask = (mask_high | mask_peak).astype('float32')
    return mask


def soft_nms(df, alpha, t1, t2):
    '''
    df: proposals generated by network;
    alpha: alpha value of Gaussian decaying function;
    t1, t2: threshold for soft nms.
    '''
    df = df.sort_values(by="score", ascending=False)
    tstart = list(df.xmin.values[:])
    tend = list(df.xmax.values[:])
    tscore = list(df.score.values[:])

    rstart = []
    rend = []
    rscore = []

    while len(tscore) > 1 and len(rscore) < 101:
        max_index = tscore.index(max(tscore))
        tmp_iou_list = iou_with_anchors(
            np.array(tstart),
            np.array(tend), tstart[max_index], tend[max_index])
        for idx in range(0, len(tscore)):
            if idx != max_index:
                tmp_iou = tmp_iou_list[idx]
                tmp_width = tend[max_index] - tstart[max_index]
                if tmp_iou > t1 + (t2 - t1) * tmp_width:
                    tscore[idx] = tscore[idx] * np.exp(-np.square(tmp_iou) /
                                                       alpha)

        rstart.append(tstart[max_index])
        rend.append(tend[max_index])
        rscore.append(tscore[max_index])
        tstart.pop(max_index)
        tend.pop(max_index)
        tscore.pop(max_index)

    newDf = pd.DataFrame()
    newDf['score'] = rscore
    newDf['xmin'] = rstart
    newDf['xmax'] = rend
    return newDf


def video_process(video_list,
                  video_dict,
                  output_path,
                  result_dict,
                  snms_alpha=0.4,
                  snms_t1=0.55,
                  snms_t2=0.9):

    for video_name in video_list:
        print("Processing video........" + video_name)
        df = pd.read_csv(os.path.join(output_path, video_name + ".csv"))
        if len(df) > 1:
            df = soft_nms(df, snms_alpha, snms_t1, snms_t2)

        video_duration = video_dict[video_name]["duration_second"]
        proposal_list = []
        for idx in range(min(100, len(df))):
            tmp_prop={"score":df.score.values[idx], \
                      "segment":[max(0,df.xmin.values[idx])*video_duration, \
                                 min(1,df.xmax.values[idx])*video_duration]}
            proposal_list.append(tmp_prop)
        result_dict[video_name[2:]] = proposal_list


def bmn_post_processing(video_dict, subset, output_path, result_path):
    video_list = video_dict.keys()
    video_list = list(video_dict.keys())
    global result_dict
    result_dict = mp.Manager().dict()
    pp_num = 12

    num_videos = len(video_list)
    num_videos_per_thread = int(num_videos / pp_num)
    processes = []
    for tid in range(pp_num - 1):
        tmp_video_list = video_list[tid * num_videos_per_thread:(tid + 1) *
                                    num_videos_per_thread]
        p = mp.Process(
            target=video_process,
            args=(tmp_video_list, video_dict, output_path, result_dict))
        p.start()
        processes.append(p)
    tmp_video_list = video_list[(pp_num - 1) * num_videos_per_thread:]
    p = mp.Process(
        target=video_process,
        args=(tmp_video_list, video_dict, output_path, result_dict))
    p.start()
    processes.append(p)
    for p in processes:
        p.join()

    result_dict = dict(result_dict)
    output_dict = {
        "version": "VERSION 1.3",
        "results": result_dict,
        "external_data": {}
    }
    outfile = open(
        os.path.join(result_path, "bmn_results_%s.json" % subset), "w")

    json.dump(output_dict, outfile)
    outfile.close()