import json
import random
from pathlib import Path

import cv2
import numpy as np

from isegm.data.base import ISDataset
from isegm.data.sample import DSample


class CocoDataset(ISDataset):
    def __init__(self, dataset_path, split="train", stuff_prob=0.0, **kwargs):
        super(CocoDataset, self).__init__(**kwargs)
        self.split = split
        self.dataset_path = Path(dataset_path)
        self.stuff_prob = stuff_prob

        self.load_samples()

    def load_samples(self):
        annotation_path = (
            self.dataset_path / "annotations" / f"panoptic_{self.split}.json"
        )
        self.labels_path = self.dataset_path / "annotations" / f"panoptic_{self.split}"
        self.images_path = self.dataset_path / self.split

        with open(annotation_path, "r") as f:
            annotation = json.load(f)

        self.dataset_samples = annotation["annotations"]

        self._categories = annotation["categories"]
        self._stuff_labels = [x["id"] for x in self._categories if x["isthing"] == 0]
        self._things_labels = [x["id"] for x in self._categories if x["isthing"] == 1]
        self._things_labels_set = set(self._things_labels)
        self._stuff_labels_set = set(self._stuff_labels)

    def get_sample(self, index) -> DSample:
        dataset_sample = self.dataset_samples[index]

        image_path = self.images_path / self.get_image_name(dataset_sample["file_name"])
        label_path = self.labels_path / dataset_sample["file_name"]

        image = cv2.imread(str(image_path))
        image = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
        label = cv2.imread(str(label_path), cv2.IMREAD_UNCHANGED).astype(np.int32)
        label = 256 * 256 * label[:, :, 0] + 256 * label[:, :, 1] + label[:, :, 2]

        instance_map = np.full_like(label, 0)
        things_ids = []
        stuff_ids = []

        for segment in dataset_sample["segments_info"]:
            class_id = segment["category_id"]
            obj_id = segment["id"]
            if class_id in self._things_labels_set:
                if segment["iscrowd"] == 1:
                    continue
                things_ids.append(obj_id)
            else:
                stuff_ids.append(obj_id)

            instance_map[label == obj_id] = obj_id

        if self.stuff_prob > 0 and random.random() < self.stuff_prob:
            instances_ids = things_ids + stuff_ids
        else:
            instances_ids = things_ids

            for stuff_id in stuff_ids:
                instance_map[instance_map == stuff_id] = 0

        return DSample(image, instance_map, objects_ids=instances_ids)

    @classmethod
    def get_image_name(cls, panoptic_name):
        return panoptic_name.replace(".png", ".jpg")