# Copyright (c) 2017-present, Facebook, Inc.
#
# 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.
##############################################################################

"""Functions for evaluating results computed for a json dataset."""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

import json
import logging
import numpy as np
import os
import uuid

from pycocotools.cocoeval import COCOeval

from core.config import cfg
from utils.io import save_object
import utils.boxes as box_utils

logger = logging.getLogger(__name__)


def evaluate_masks(
    json_dataset,
    all_boxes,
    all_segms,
    output_dir,
    use_salt=True,
    cleanup=False
):
    res_file = os.path.join(
        output_dir, 'segmentations_' + json_dataset.name + '_results'
    )
    if use_salt:
        res_file += '_{}'.format(str(uuid.uuid4()))
    res_file += '.json'
    _write_coco_segms_results_file(
        json_dataset, all_boxes, all_segms, res_file)
    # Only do evaluation on non-test sets (annotations are undisclosed on test)
    if json_dataset.name.find('test') == -1:
        coco_eval = _do_segmentation_eval(json_dataset, res_file, output_dir)
    else:
        coco_eval = None
    # Optionally cleanup results json file
    if cleanup:
        os.remove(res_file)
    return coco_eval


def _write_coco_segms_results_file(
    json_dataset, all_boxes, all_segms, res_file
):
    # [{"image_id": 42,
    #   "category_id": 18,
    #   "segmentation": [...],
    #   "score": 0.236}, ...]
    results = []
    for cls_ind, cls in enumerate(json_dataset.classes):
        if cls == '__background__':
            continue
        if cls_ind >= len(all_boxes):
            break
        cat_id = json_dataset.category_to_id_map[cls]
        results.extend(_coco_segms_results_one_category(
            json_dataset, all_boxes[cls_ind], all_segms[cls_ind], cat_id))
    logger.info(
        'Writing segmentation results json to: {}'.format(
            os.path.abspath(res_file)))
    with open(res_file, 'w') as fid:
        json.dump(results, fid)


def _coco_segms_results_one_category(json_dataset, boxes, segms, cat_id):
    results = []
    image_ids = json_dataset.COCO.getImgIds()
    image_ids.sort()
    assert len(boxes) == len(image_ids)
    assert len(segms) == len(image_ids)
    for i, image_id in enumerate(image_ids):
        dets = boxes[i]
        rles = segms[i]

        if isinstance(dets, list) and len(dets) == 0:
            continue

        dets = dets.astype(np.float)
        scores = dets[:, -1]

        results.extend(
            [{'image_id': image_id,
              'category_id': cat_id,
              'segmentation': rles[k],
              'score': scores[k]}
              for k in range(dets.shape[0])])

    return results


def _do_segmentation_eval(json_dataset, res_file, output_dir):
    coco_dt = json_dataset.COCO.loadRes(str(res_file))
    coco_eval = COCOeval(json_dataset.COCO, coco_dt, 'segm')
    coco_eval.evaluate()
    coco_eval.accumulate()
    _log_detection_eval_metrics(json_dataset, coco_eval)
    eval_file = os.path.join(output_dir, 'segmentation_results.pkl')
    save_object(coco_eval, eval_file)
    logger.info('Wrote json eval results to: {}'.format(eval_file))
    return coco_eval


def evaluate_boxes(
    json_dataset, all_boxes, output_dir, use_salt=True, cleanup=False
):
    res_file = os.path.join(
        output_dir, 'bbox_' + json_dataset.name + '_results'
    )
    if use_salt:
        res_file += '_{}'.format(str(uuid.uuid4()))
    res_file += '.json'
    _write_coco_bbox_results_file(json_dataset, all_boxes, res_file)
    # Only do evaluation on non-test sets (annotations are undisclosed on test)
    if json_dataset.name.find('test') == -1:
        coco_eval = _do_detection_eval(json_dataset, res_file, output_dir)
    else:
        coco_eval = None
    # Optionally cleanup results json file
    if cleanup:
        os.remove(res_file)
    return coco_eval


def _write_coco_bbox_results_file(json_dataset, all_boxes, res_file):
    # [{"image_id": 42,
    #   "category_id": 18,
    #   "bbox": [258.15,41.29,348.26,243.78],
    #   "score": 0.236}, ...]
    results = []
    for cls_ind, cls in enumerate(json_dataset.classes):
        if cls == '__background__':
            continue
        if cls_ind >= len(all_boxes):
            break
        cat_id = json_dataset.category_to_id_map[cls]
        results.extend(_coco_bbox_results_one_category(
            json_dataset, all_boxes[cls_ind], cat_id))
    logger.info(
        'Writing bbox results json to: {}'.format(os.path.abspath(res_file)))
    with open(res_file, 'w') as fid:
        json.dump(results, fid)


def _coco_bbox_results_one_category(json_dataset, boxes, cat_id):
    results = []
    image_ids = json_dataset.COCO.getImgIds()
    image_ids.sort()
    assert len(boxes) == len(image_ids)
    for i, image_id in enumerate(image_ids):
        dets = boxes[i]
        if isinstance(dets, list) and len(dets) == 0:
            continue
        dets = dets.astype(np.float)
        scores = dets[:, -1]
        xywh_dets = box_utils.xyxy_to_xywh(dets[:, 0:4])
        xs = xywh_dets[:, 0]
        ys = xywh_dets[:, 1]
        ws = xywh_dets[:, 2]
        hs = xywh_dets[:, 3]
        results.extend(
            [{'image_id': image_id,
              'category_id': cat_id,
              'bbox': [xs[k], ys[k], ws[k], hs[k]],
              'score': scores[k]} for k in range(dets.shape[0])])
    return results


def _do_detection_eval(json_dataset, res_file, output_dir):
    coco_dt = json_dataset.COCO.loadRes(str(res_file))
    coco_eval = COCOeval(json_dataset.COCO, coco_dt, 'bbox')
    coco_eval.evaluate()
    coco_eval.accumulate()
    _log_detection_eval_metrics(json_dataset, coco_eval)
    eval_file = os.path.join(output_dir, 'detection_results.pkl')
    save_object(coco_eval, eval_file)
    logger.info('Wrote json eval results to: {}'.format(eval_file))
    return coco_eval


def _log_detection_eval_metrics(json_dataset, coco_eval):
    def _get_thr_ind(coco_eval, thr):
        ind = np.where((coco_eval.params.iouThrs > thr - 1e-5) &
                       (coco_eval.params.iouThrs < thr + 1e-5))[0][0]
        iou_thr = coco_eval.params.iouThrs[ind]
        assert np.isclose(iou_thr, thr)
        return ind

    IoU_lo_thresh = 0.5
    IoU_hi_thresh = 0.95
    ind_lo = _get_thr_ind(coco_eval, IoU_lo_thresh)
    ind_hi = _get_thr_ind(coco_eval, IoU_hi_thresh)
    # precision has dims (iou, recall, cls, area range, max dets)
    # area range index 0: all area ranges
    # max dets index 2: 100 per image
    precision = coco_eval.eval['precision'][ind_lo:(ind_hi + 1), :, :, 0, 2]
    ap_default = np.mean(precision[precision > -1])
    logger.info(
        '~~~~ Mean and per-category AP @ IoU=[{:.2f},{:.2f}] ~~~~'.format(
            IoU_lo_thresh, IoU_hi_thresh))
    logger.info('{:.1f}'.format(100 * ap_default))
    for cls_ind, cls in enumerate(json_dataset.classes):
        if cls == '__background__':
            continue
        # minus 1 because of __background__
        precision = coco_eval.eval['precision'][
            ind_lo:(ind_hi + 1), :, cls_ind - 1, 0, 2]
        ap = np.mean(precision[precision > -1])
        logger.info('{:.1f}'.format(100 * ap))
    logger.info('~~~~ Summary metrics ~~~~')
    coco_eval.summarize()


def evaluate_box_proposals(
    json_dataset, roidb, thresholds=None, area='all', limit=None
):
    """Evaluate detection proposal recall metrics. This function is a much
    faster alternative to the official COCO API recall evaluation code. However,
    it produces slightly different results.
    """
    # Record max overlap value for each gt box
    # Return vector of overlap values
    areas = {
        'all': 0,
        'small': 1,
        'medium': 2,
        'large': 3,
        '96-128': 4,
        '128-256': 5,
        '256-512': 6,
        '512-inf': 7}
    area_ranges = [
        [0**2, 1e5**2],    # all
        [0**2, 32**2],     # small
        [32**2, 96**2],    # medium
        [96**2, 1e5**2],   # large
        [96**2, 128**2],   # 96-128
        [128**2, 256**2],  # 128-256
        [256**2, 512**2],  # 256-512
        [512**2, 1e5**2]]  # 512-inf
    assert area in areas, 'Unknown area range: {}'.format(area)
    area_range = area_ranges[areas[area]]
    gt_overlaps = np.zeros(0)
    num_pos = 0
    for entry in roidb:
        gt_inds = np.where(
            (entry['gt_classes'] > 0) & (entry['is_crowd'] == 0))[0]
        gt_boxes = entry['boxes'][gt_inds, :]
        gt_areas = entry['seg_areas'][gt_inds]
        valid_gt_inds = np.where(
            (gt_areas >= area_range[0]) & (gt_areas <= area_range[1]))[0]
        gt_boxes = gt_boxes[valid_gt_inds, :]
        num_pos += len(valid_gt_inds)
        non_gt_inds = np.where(entry['gt_classes'] == 0)[0]
        boxes = entry['boxes'][non_gt_inds, :]
        if boxes.shape[0] == 0:
            continue
        if limit is not None and boxes.shape[0] > limit:
            boxes = boxes[:limit, :]
        overlaps = box_utils.bbox_overlaps(
            boxes.astype(dtype=np.float32, copy=False),
            gt_boxes.astype(dtype=np.float32, copy=False))
        _gt_overlaps = np.zeros((gt_boxes.shape[0]))
        for j in range(min(boxes.shape[0], gt_boxes.shape[0])):
            # find which proposal box maximally covers each gt box
            argmax_overlaps = overlaps.argmax(axis=0)
            # and get the iou amount of coverage for each gt box
            max_overlaps = overlaps.max(axis=0)
            # find which gt box is 'best' covered (i.e. 'best' = most iou)
            gt_ind = max_overlaps.argmax()
            gt_ovr = max_overlaps.max()
            assert gt_ovr >= 0
            # find the proposal box that covers the best covered gt box
            box_ind = argmax_overlaps[gt_ind]
            # record the iou coverage of this gt box
            _gt_overlaps[j] = overlaps[box_ind, gt_ind]
            assert _gt_overlaps[j] == gt_ovr
            # mark the proposal box and the gt box as used
            overlaps[box_ind, :] = -1
            overlaps[:, gt_ind] = -1
        # append recorded iou coverage level
        gt_overlaps = np.hstack((gt_overlaps, _gt_overlaps))

    gt_overlaps = np.sort(gt_overlaps)
    if thresholds is None:
        step = 0.05
        thresholds = np.arange(0.5, 0.95 + 1e-5, step)
    recalls = np.zeros_like(thresholds)
    # compute recall for each iou threshold
    for i, t in enumerate(thresholds):
        recalls[i] = (gt_overlaps >= t).sum() / float(num_pos)
    # ar = 2 * np.trapz(recalls, thresholds)
    ar = recalls.mean()
    return {'ar': ar, 'recalls': recalls, 'thresholds': thresholds,
            'gt_overlaps': gt_overlaps, 'num_pos': num_pos}
