"""Download media URLs from ThreadData via stdlib urllib into a local directory."""
from __future__ import annotations
import argparse
import json
import sys
from pathlib import Path
from urllib.request import urlopen
from urllib.error import URLError
from urllib.parse import urlparse, parse_qs
try:
 from scripts.twitter_threads.error_types import ErrorInfo, make_error, Result, PostData, ThreadData, thread_from_dict
except ImportError:
 from error_types import ErrorInfo, make_error, Result, PostData, ThreadData, thread_from_dict

def _classify(url: str) -> tuple[str, str]:
 parsed = urlparse(url)
 path = parsed.path
 if "video.twimg.com" in parsed.netloc or path.endswith(".mp4"):
  if "tweet_video" in path:
   return ("gif", "mp4")
  return ("vid", "mp4")
 qs = parse_qs(parsed.query)
 fmt = qs.get("format", [""])[0]
 if fmt:
  return ("img", fmt)
 if "." in path:
  return ("img", path.rsplit(".", 1)[-1])
 return ("img", "jpg")

def media_names_for_post(post: PostData) -> list[str]:
 counters: dict[str, int] = {}
 names: list[str] = []
 for url in post.media_urls:
  kind, ext = _classify(url)
  counters[kind] = counters.get(kind, 0) + 1
  names.append(f"{post.post_id}_{kind}{counters[kind]}.{ext}")
 return names

def download_media(thread: ThreadData, output_dir: Path) -> Result[list[Path]]:
 try:
  output_dir.mkdir(parents=True, exist_ok=True)
 except OSError as e:
  return Result.err(make_error("WriteError", "download_media", str(e)))
 paths: list[Path] = []
 for post in thread.posts:
  names = media_names_for_post(post)
  for url, name in zip(post.media_urls, names):
   target = output_dir / name
   if target.exists() and target.stat().st_size > 0:
    paths.append(target)
    continue
   try:
    with urlopen(url) as resp:
     data = resp.read()
   except URLError as e:
    return Result.err(make_error("HttpError", "download_media", str(e)))
   try:
    target.write_bytes(data)
   except OSError as e:
    return Result.err(make_error("WriteError", "download_media", str(e)))
   paths.append(target)
 return Result.ok(paths)

def main(argv: list[str] | None = None) -> int:
 parser = argparse.ArgumentParser(description="Download media for a Twitter/X thread_data.json.")
 parser.add_argument("--input", type=Path, required=True, help="thread_data.json path")
 parser.add_argument("--output", type=Path, required=True, help="media output directory")
 args = parser.parse_args(argv)
 try:
  raw = args.input.read_text(encoding="utf-8")
 except OSError as e:
  sys.stderr.write(f"error: ReadError: {e}\n")
  return 1
 try:
  data = json.loads(raw)
 except json.JSONDecodeError as e:
  sys.stderr.write(f"error: JsonParseError: {e}\n")
  return 1
 thread = thread_from_dict(data)
 result = download_media(thread, args.output)
 if not result.is_ok:
  sys.stderr.write(f"error: {result.error.kind}: {result.error.detail}\n")
  return 1
 print(f"downloaded {len(result.data)} file(s) to {args.output}")
 return 0


if __name__ == "__main__":
 sys.exit(main())