import os
import pathlib
import subprocess
import urllib.parse
from typing import List, Optional

from fastapi import FastAPI, HTTPException, Response, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import FileResponse

MEDIA_DIR = pathlib.Path(os.getenv("MEDIA_VIDEOS_DIR", "/mnt/videos")).resolve()
THUMBS_DIR = pathlib.Path(os.getenv("MEDIA_THUMBS_DIR", MEDIA_DIR / ".thumbnails")).resolve()

app = FastAPI(title="Media API", version="0.1.0")

# CORS for dashboard at exp-dash:8080 (and localhost for convenience)
app.add_middleware(
    CORSMiddleware,
    allow_origins=["http://exp-dash:8080", "http://localhost:8080"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"]
)


def list_video_files() -> List[pathlib.Path]:
    exts = {".mp4", ".avi", ".mov", ".mkv"}
    files: List[pathlib.Path] = []
    for root, _, fnames in os.walk(MEDIA_DIR):
        # skip thumbnails dir
        if THUMBS_DIR.as_posix() in pathlib.Path(root).as_posix():
            continue
        for f in fnames:
            p = pathlib.Path(root) / f
            if p.suffix.lower() in exts:
                files.append(p)
    return sorted(files, key=lambda p: p.stat().st_mtime, reverse=True)


def file_id_from_path(p: pathlib.Path) -> str:
    return urllib.parse.quote_plus(p.relative_to(MEDIA_DIR).as_posix())


def path_from_file_id(fid: str) -> pathlib.Path:
    rel = urllib.parse.unquote_plus(fid)
    p = (MEDIA_DIR / rel).resolve()
    if not p.is_file() or MEDIA_DIR not in p.parents:
        raise HTTPException(status_code=404, detail="Video not found")
    return p


def ensure_thumbnail(p: pathlib.Path, width: int = 320, height: int = 180) -> pathlib.Path:
    THUMBS_DIR.mkdir(parents=True, exist_ok=True)
    thumb_name = file_id_from_path(p) + f"_{width}x{height}.jpg"
    out = THUMBS_DIR / thumb_name
    if out.exists():
        return out
    # generate from 1s offset or 0 if too short
    cmd = [
        "ffmpeg", "-y",
        "-ss", "1",
        "-i", str(p),
        "-vframes", "1",
        "-vf", f"scale='min({width},iw)':-2,scale={width}:{height}:force_original_aspect_ratio=decrease,pad={width}:{height}:(ow-iw)/2:(oh-ih)/2",
        str(out)
    ]
    try:
        subprocess.run(cmd, check=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    except subprocess.CalledProcessError:
        raise HTTPException(status_code=500, detail="Failed to generate thumbnail")
    return out


@app.get("/health")
def health() -> dict:
    return {"status": "ok"}


@app.get("/videos/")
def list_videos(camera_name: Optional[str] = None, start_date: Optional[str] = None, end_date: Optional[str] = None,
                limit: int = 24, page: int = 1) -> dict:
    files = list_video_files()
    # basic filtering placeholder (camera_name can be inferred from path segments)
    if camera_name:
        files = [p for p in files if camera_name in p.as_posix()]
    total = len(files)
    start = max(0, (page - 1) * limit)
    slice_ = files[start:start + limit]
    items = []
    for p in slice_:
        stat = p.stat()
        items.append({
            "file_id": file_id_from_path(p),
            "camera_name": p.parent.name,
            "filename": p.name,
            "file_size_bytes": stat.st_size,
            "format": p.suffix.lstrip('.'),
            "status": "completed",
            "created_at": int(stat.st_mtime),
            "is_streamable": True,
            "needs_conversion": False,
        })
    total_pages = (total + limit - 1) // limit if limit else 1
    return {
        "videos": items,
        "total_count": total,
        "page": page,
        "total_pages": total_pages,
    }


@app.get("/videos/{file_id:path}/thumbnail")
def get_thumbnail(file_id: str, width: int = 320, height: int = 180):
    p = path_from_file_id(file_id)
    thumb = ensure_thumbnail(p, width, height)
    return FileResponse(thumb, media_type="image/jpeg")

# Convenience endpoint: pass file_id via query instead of path (accepts raw or URL-encoded)
@app.get("/videos/thumbnail")
def get_thumbnail_q(file_id: str, width: int = 320, height: int = 180):
    p = path_from_file_id(file_id)
    thumb = ensure_thumbnail(p, width, height)
    return FileResponse(thumb, media_type="image/jpeg")


def open_file_range(path: pathlib.Path, start: int, end: Optional[int]):
    file_size = path.stat().st_size
    if end is None or end >= file_size:
        end = file_size - 1
    length = end - start + 1
    with open(path, 'rb') as f:
        f.seek(start)
        chunk = f.read(length)
    return chunk, file_size, start, end


@app.get("/videos/{file_id:path}/stream")
def stream_file(request: Request, file_id: str):
    p = path_from_file_id(file_id)
    range_header = request.headers.get("range")
    if not range_header:
        return FileResponse(p, media_type="video/mp4")
    # parse bytes=START-END
    range_value = range_header.strip().lower().replace("bytes=", "")
    start_str, _, end_str = range_value.partition("-")
    try:
        start = int(start_str) if start_str else 0
        end = int(end_str) if end_str else None
    except ValueError:
        raise HTTPException(status_code=400, detail="Bad Range header")
    chunk, size, start, end = open_file_range(p, start, end)
    headers = {
        "Content-Range": f"bytes {start}-{end}/{size}",
        "Accept-Ranges": "bytes",
        "Content-Length": str(len(chunk)),
        "Content-Type": "video/mp4",
        "Cache-Control": "no-cache, no-store, must-revalidate",
        "Access-Control-Allow-Origin": "*",
    }
    return Response(content=chunk, status_code=206, headers=headers)

# Convenience endpoint: pass file_id via query instead of path (accepts raw or URL-encoded)
@app.get("/videos/stream")
def stream_file_q(request: Request, file_id: str):
    return stream_file(request, file_id)