import os
import requests

YT_API_KEY = os.getenv("YT_API_KEY")


def get_latest_video_id(channel_id, device_name=None, playlist_id=None):
    """
    Return the videoId of the most recently published video from either:
      - a specific playlist (if playlist_id is provided or can be resolved from device_name), or
      - the channel (if only channel_id is provided).

    This does NOT rely on playlist UI ordering; it walks the whole playlist and
    picks the newest item by snippet.publishedAt.
    """
    if device_name is None and playlist_id is None:
        raise ValueError("Must specify either device_name or playlist_id")

    if device_name is not None and playlist_id is not None:
        # Keep existing behavior
        print("Both device_name and playlist_id entered.. device_name will be ignored.")

    # ------------------------------------------------------------------
    # 1) If we only know the device_name, resolve playlist_id from channel
    # ------------------------------------------------------------------
    if playlist_id is None:
        playlists_url = "https://www.googleapis.com/youtube/v3/playlists"
        playlists_params = {
            "part": "snippet",
            "channelId": channel_id,
            "maxResults": 50,
            "key": YT_API_KEY,
        }

        res = requests.get(playlists_url, params=playlists_params)
        res.raise_for_status()
        playlists = res.json().get("items", [])

        for p in playlists:
            title = p["snippet"]["title"].lower()
            if device_name.lower() in title:
                playlist_id = p["id"]
                break

        if not playlist_id:
            raise Exception(f"No playlist found matching device name '{device_name}'")

    # ------------------------------------------------------------------
    # 2) If we have a playlist_id, walk ALL pages and find newest item
    # ------------------------------------------------------------------
    if playlist_id:
        playlist_url = "https://www.googleapis.com/youtube/v3/playlistItems"
        latest_video_id = None
        latest_published_at = None
        page_token = None

        while True:
            playlist_params = {
                "part": "snippet,contentDetails",
                "playlistId": playlist_id,
                "maxResults": 50,  # API max
                "key": YT_API_KEY,
            }
            if page_token:
                playlist_params["pageToken"] = page_token

            playlist_res = requests.get(playlist_url, params=playlist_params)
            playlist_res.raise_for_status()
            data = playlist_res.json()

            for item in data.get("items", []):
                snippet = item.get("snippet", {})
                published_at = snippet.get("publishedAt")
                if not published_at:
                    continue

                # For playlistItems, videoId lives in contentDetails.videoId
                video_id = item.get("contentDetails", {}).get("videoId")
                if not video_id:
                    # Fallback to snippet.resourceId if needed
                    video_id = (
                        snippet.get("resourceId", {}) or {}
                    ).get("videoId")

                if not video_id:
                    continue

                if latest_published_at is None or published_at > latest_published_at:
                    latest_published_at = published_at
                    latest_video_id = video_id

            page_token = data.get("nextPageToken")
            if not page_token:
                break

        return latest_video_id

    # ------------------------------------------------------------------
    # 3) Fallback: no playlist, just get latest video on the channel
    # ------------------------------------------------------------------
    search_url = "https://www.googleapis.com/youtube/v3/search"
    search_params = {
        "part": "snippet",
        "channelId": channel_id,
        "maxResults": 1,
        "order": "date",  # newest first
        "type": "video",
        "key": YT_API_KEY,
    }

    res = requests.get(search_url, params=search_params)
    res.raise_for_status()
    items = res.json().get("items", [])

    if not items:
        return None

    return items[0]["id"]["videoId"]