import os
import numpy as np
import copy
from .base_dataset import BaseDataset
from ltr.data.image_loader import jpeg4py_loader
import torch
from pycocotools.coco import COCO
from collections import OrderedDict
from ltr.admin.environment import env_settings


class MSCOCOSeq(BaseDataset):
    """ The COCO dataset. COCO is an image dataset. Thus, we treat each image as a sequence of length 1.

    Publication:
        Microsoft COCO: Common Objects in Context.
        Tsung-Yi Lin, Michael Maire, Serge J. Belongie, Lubomir D. Bourdev, Ross B. Girshick, James Hays, Pietro Perona,
        Deva Ramanan, Piotr Dollar and C. Lawrence Zitnick
        ECCV, 2014
        https://arxiv.org/pdf/1405.0312.pdf

    Download the images along with annotations from http://cocodataset.org/#download. The root folder should be
    organized as follows.
        - coco_root
            - annotations
                - instances_train2014.json
            - images
                - train2014

    Note: You also have to install the coco pythonAPI from https://github.com/cocodataset/cocoapi.
    """

    def __init__(self, root=None, image_loader=jpeg4py_loader):
        root = env_settings().coco_dir if root is None else root
        super().__init__(root, image_loader)

        self.img_pth = os.path.join(root, 'train2014/')
        self.anno_path = os.path.join(root, 'annotations/instances_train2014.json')

        # Load the COCO set.
        self.coco_set = COCO(self.anno_path)

        self.cats = self.coco_set.cats

        self.class_list = self.get_class_list()     # the parent class thing would happen in the sampler

        self.sequence_list = self._get_sequence_list()

        self.seq_per_class = self._build_seq_per_class()

    def _get_sequence_list(self):
        ann_list = list(self.coco_set.anns.keys())
        seq_list = [a for a in ann_list if self.coco_set.anns[a]['iscrowd'] == 0]

        return seq_list

    def is_video_sequence(self):
        return False

    def get_num_classes(self):
        return len(self.class_list)

    def get_name(self):
        return 'coco'

    def has_class_info(self):
        return True

    def get_class_list(self):
        class_list = []
        for cat_id in self.cats.keys():
            class_list.append(self.cats[cat_id]['name'])
        return class_list

    def has_segmentation_info(self):
        return True

    def get_num_sequences(self):
        return len(self.sequence_list)

    def _build_seq_per_class(self):
        seq_per_class = {}
        for i, seq in enumerate(self.sequence_list):
            class_name = self.cats[self.coco_set.anns[seq]['category_id']]['name']
            if class_name not in seq_per_class:
                seq_per_class[class_name] = [i]
            else:
                seq_per_class[class_name].append(i)

        return seq_per_class

    def get_sequences_in_class(self, class_name):
        return self.seq_per_class[class_name]

    def get_sequence_info(self, seq_id):
        anno = self._get_anno(seq_id)

        bbox = torch.Tensor(anno['bbox']).view(1, 4)

        mask = self.coco_set.annToMask(anno)
        mask = np.array(mask)
        mask = mask.reshape(1, mask.shape[0], mask.shape[1], 1)

        valid = (bbox[:, 2] > 0) & (bbox[:, 3] > 0)
        visible = valid.clone()

        return {'bbox': bbox, 'mask': mask, 'valid': valid, 'visible': visible}

    def _get_anno(self, seq_id):
        anno = self.coco_set.anns[self.sequence_list[seq_id]]

        return anno

    def _get_frames(self, seq_id):
        path = self.coco_set.loadImgs([self.coco_set.anns[self.sequence_list[seq_id]]['image_id']])[0]['file_name']
        img = self.image_loader(os.path.join(self.img_pth, path))
        return img

    def get_meta_info(self, seq_id):
        try:
            cat_dict_current = self.cats[self.coco_set.anns[self.sequence_list[seq_id]]['category_id']]
            object_meta = OrderedDict({'object_class': cat_dict_current['name'],
                                       'motion_class': None,
                                       'major_class': cat_dict_current['supercategory'],
                                       'root_class': None,
                                       'motion_adverb': None})
        except:
            object_meta = OrderedDict({'object_class': None,
                                       'motion_class': None,
                                       'major_class': None,
                                       'root_class': None,
                                       'motion_adverb': None})
        return object_meta

    def get_frames(self, seq_id=None, frame_ids=None, anno=None):
        # COCO is an image dataset. Thus we replicate the image denoted by seq_id len(frame_ids) times, and return a
        # list containing these replicated images.
        frame = self._get_frames(seq_id)

        frame_list = [frame.copy() for _ in frame_ids]

        if anno is None:
            anno = self.get_sequence_info(seq_id)

        anno_frames = {}
        for key, value in anno.items():
            anno_frames[key] = [value[0, ...] for _ in frame_ids]

        object_meta = self.get_meta_info(seq_id)

        return frame_list, anno_frames, object_meta
