# Copyright (c) 2021 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 os
import numpy as np
import copy
import motmetrics as mm
mm.lap.default_solver = 'lap'

__all__ = [
    'read_mot_results',
    'unzip_objs',
    'MOTEvaluator',
]


def read_mot_results(filename, is_gt=False, is_ignore=False):
    valid_labels = {1}
    ignore_labels = {2, 7, 8, 12}
    results_dict = dict()
    if os.path.isfile(filename):
        with open(filename, 'r') as f:
            for line in f.readlines():
                linelist = line.split(',')
                if len(linelist) < 7:
                    continue
                fid = int(linelist[0])
                if fid < 1:
                    continue
                results_dict.setdefault(fid, list())

                box_size = float(linelist[4]) * float(linelist[5])

                if is_gt:
                    if 'MOT16-' in filename or 'MOT17-' in filename:
                        label = int(float(linelist[7]))
                        mark = int(float(linelist[6]))
                        if mark == 0 or label not in valid_labels:
                            continue
                    score = 1
                elif is_ignore:
                    if 'MOT16-' in filename or 'MOT17-' in filename:
                        label = int(float(linelist[7]))
                        vis_ratio = float(linelist[8])
                        if label not in ignore_labels and vis_ratio >= 0:
                            continue
                    else:
                        continue
                    score = 1
                else:
                    score = float(linelist[6])

                tlwh = tuple(map(float, linelist[2:6]))
                target_id = int(linelist[1])

                results_dict[fid].append((tlwh, target_id, score))
    return results_dict


"""
labels={'ped', ...			    % 1
        'person_on_vhcl', ...	% 2
        'car', ...				% 3
        'bicycle', ...			% 4
        'mbike', ...			% 5
        'non_mot_vhcl', ...		% 6
        'static_person', ...	% 7
        'distractor', ...		% 8
        'occluder', ...			% 9
        'occluder_on_grnd', ...	% 10
        'occluder_full', ...	% 11
        'reflection', ...		% 12
        'crowd' ...			    % 13
};
"""


def unzip_objs(objs):
    if len(objs) > 0:
        tlwhs, ids, scores = zip(*objs)
    else:
        tlwhs, ids, scores = [], [], []
    tlwhs = np.asarray(tlwhs, dtype=float).reshape(-1, 4)
    return tlwhs, ids, scores


class MOTEvaluator(object):
    def __init__(self, data_root, seq_name, data_type):
        self.data_root = data_root
        self.seq_name = seq_name
        self.data_type = data_type

        self.load_annotations()
        self.reset_accumulator()

    def load_annotations(self):
        assert self.data_type == 'mot'
        gt_filename = os.path.join(self.data_root, self.seq_name, 'gt',
                                   'gt.txt')
        self.gt_frame_dict = read_mot_results(gt_filename, is_gt=True)
        self.gt_ignore_frame_dict = read_mot_results(
            gt_filename, is_ignore=True)

    def reset_accumulator(self):
        self.acc = mm.MOTAccumulator(auto_id=True)

    def eval_frame(self, frame_id, trk_tlwhs, trk_ids, rtn_events=False):
        # results
        trk_tlwhs = np.copy(trk_tlwhs)
        trk_ids = np.copy(trk_ids)

        # gts
        gt_objs = self.gt_frame_dict.get(frame_id, [])
        gt_tlwhs, gt_ids = unzip_objs(gt_objs)[:2]

        # ignore boxes
        ignore_objs = self.gt_ignore_frame_dict.get(frame_id, [])
        ignore_tlwhs = unzip_objs(ignore_objs)[0]

        # remove ignored results
        keep = np.ones(len(trk_tlwhs), dtype=bool)
        iou_distance = mm.distances.iou_matrix(
            ignore_tlwhs, trk_tlwhs, max_iou=0.5)
        if len(iou_distance) > 0:
            match_is, match_js = mm.lap.linear_sum_assignment(iou_distance)
            match_is, match_js = map(lambda a: np.asarray(a, dtype=int), [match_is, match_js])
            match_ious = iou_distance[match_is, match_js]

            match_js = np.asarray(match_js, dtype=int)
            match_js = match_js[np.logical_not(np.isnan(match_ious))]
            keep[match_js] = False
            trk_tlwhs = trk_tlwhs[keep]
            trk_ids = trk_ids[keep]

        # get distance matrix
        iou_distance = mm.distances.iou_matrix(gt_tlwhs, trk_tlwhs, max_iou=0.5)

        # acc
        self.acc.update(gt_ids, trk_ids, iou_distance)

        if rtn_events and iou_distance.size > 0 and hasattr(self.acc,
                                                            'last_mot_events'):
            events = self.acc.last_mot_events  # only supported by https://github.com/longcw/py-motmetrics
        else:
            events = None
        return events

    def eval_file(self, filename):
        self.reset_accumulator()

        result_frame_dict = read_mot_results(filename, is_gt=False)
        frames = sorted(list(set(result_frame_dict.keys())))
        for frame_id in frames:
            trk_objs = result_frame_dict.get(frame_id, [])
            trk_tlwhs, trk_ids = unzip_objs(trk_objs)[:2]
            self.eval_frame(frame_id, trk_tlwhs, trk_ids, rtn_events=False)

        return self.acc

    @staticmethod
    def get_summary(accs,
                    names,
                    metrics=('mota', 'num_switches', 'idp', 'idr', 'idf1',
                             'precision', 'recall')):
        names = copy.deepcopy(names)
        if metrics is None:
            metrics = mm.metrics.motchallenge_metrics
        metrics = copy.deepcopy(metrics)

        mh = mm.metrics.create()
        summary = mh.compute_many(
            accs, metrics=metrics, names=names, generate_overall=True)
        return summary

    @staticmethod
    def save_summary(summary, filename):
        import pandas as pd
        writer = pd.ExcelWriter(filename)
        summary.to_excel(writer)
        writer.save()
