from dataclasses import dataclass, asdict

from texture import ImageTextureImmichAsset

@dataclass
class Album:
    id: str
    range_start: int
    range_end: int
    assets_list: list[str] = None

    @property
    def assets_count(self):
        return end - start


@dataclass
class CallbackStateData:
    asset_index: int
    movement: int
    assets: list[str]

    @classmethod
    def from_lctl(cls, l):
        si = (l.asset_index - 5) % l.asset_count
        ei = (l.asset_index + 6) % l.asset_count
        sa = l.assets[si:ei] if si < ei else l.assets[si:] + l.assets[:ei]
        assets = [ a["id"] for a in sa ]
        return cls(
            asset_index=l.asset_index,
            movement=l.last_movement,
            assets=assets,
        )


class LazyCachingTextureList():
    def __init__(self, immich_connector, album_ids, max_cache_items=100, change_callback=None):
        self.immich_connector = immich_connector
        assert max_cache_items >= 20, "Minimum cache items is 20"  # Double small radius

        # Ring buffer
        self.cache_length = max_cache_items
        self.cache = [None] * max_cache_items
        self.radius_small = 10
        self.radius_large = int(max_cache_items / 2)
        self.cache_items_behind = 0
        self.cache_items_ahead = 0
        self.cache_index = 0
        self.asset_index = 0
        self.asset_count = 0
        self.last_movement = 0

        self.cached_items = 0

        self.album_keys = album_ids
        # TODO simplify album handling, dont need classes, etc.
        self.albums = self._get_albums()
        self.assets = self._get_album_assets()

        self.change_callback = change_callback

    def index_in_cache_range(self, index):
        index_range_low  = (self.asset_index - self.cache_items_behind) % self.asset_count
        index_range_high = (self.asset_index + self.cache_items_ahead ) % self.asset_count
        if index_range_low > index_range_high:
            return index_range_low <= index or index <= index_range_high
        return index_range_low <= index <= index_range_high

    def _get_albums(self):
        albums = []
        self.asset_count = i = 0
        albums_info = self.immich_connector.load_all_albums()
        for album_info in albums_info:
            id = album_info["id"]
            if id not in self.album_keys:
                continue
            asset_count = album_info["assetCount"]
            albums.append(Album(id, i, i + asset_count))
            i += asset_count + 1
            self.asset_count += asset_count
        return albums

    def _get_album_assets(self):
        assets = []
        for album in self.albums:
            assets += self.immich_connector.load_album_assets(album.id)
        return assets

    def _fill_cache(self, current_radius, final_radius, step):
        if current_radius >= final_radius:
            return current_radius

        for i in range(current_radius * step, final_radius * step, step):
            cache_index = (self.cache_index + i) % self.cache_length
            asset_index = (self.asset_index + i) % self.asset_count
            if self.cache[cache_index]:
                self.cache[cache_index].free()  # Since this is a ring buffer, textures outside of range can just get free'd here
            asset = self.assets[asset_index]
            tex = ImageTextureImmichAsset(asset, asset_index)
            self.immich_connector.load_texture_async(self, tex)
            self.cache[cache_index] = tex
            self.cached_items += 1

        return max(current_radius, final_radius)

    def _update_cache_get_item(self, asset_index):
        prev_asset_index = self.asset_index
        self.asset_index = asset_index % self.asset_count
        #if prev_asset_index == asset_index:
        #    return self.cache[self.cache_index]
        # Movement is the distance between the previous and current index in the assets list
        # Since the list wraps around, fastest method is just to get the abs min of the 3 cases
        movement = min(
            asset_index - prev_asset_index,       # No list wrap
            asset_index - self.asset_count,       # Wrap backwards (0  -> -1)
            self.asset_count - prev_asset_index,  # Wrap forwards  (-1 ->  0)
        key=abs)
        self.last_movement = movement
        self.cache_index = (self.cache_index + movement) % self.cache_length

        ahead  = max(0, self.cache_items_ahead  - movement)
        behind = max(0, self.cache_items_behind + movement)

        if ahead + behind > self.cache_length:
            if movement < 0:
                ahead += movement
            else:
                behind -= movement

        #print("AHEAD/BEHIND/CACHE_I/ASSET_I/MOVEMENT:", ahead, behind, self.cache_index, self.asset_index, movement)
        # TODO if ahead is 0 then clear queue

        ahead  = self._fill_cache(ahead,  self.radius_small, +1)  # Fill small radius ahead of cache_index
        behind = self._fill_cache(behind, self.radius_small, -1)  # Fill small radius behind cache_index
        ahead  = self._fill_cache(ahead,  self.radius_large, +1)  # Fill large radius ahead of cache_index

        self.cache_items_ahead = ahead
        self.cache_items_behind = behind

        # Perform callback
        if prev_asset_index != asset_index and self.change_callback:
            self.change_callback(asdict(CallbackStateData.from_lctl(self)))

        return self.cache[self.cache_index]

    def __len__(self):
        return self.asset_count

    def __getitem__(self, index):
        i = index % self.asset_count
        if abs(index) > i:
            raise IndexError("Index out of bounds")
        return self._update_cache_get_item(index)