"""自动准备官方 scrcpy-server（与 vendor/scrcpy-server.version 版本一致），供 Web 真流 adb push 使用。"""
from __future__ import annotations

import os
import sys
import time
import urllib.error
import urllib.request
from pathlib import Path

# 官方发行资产名：scrcpy-server-v{version}（无扩展名，实为 JAR）
_GITHUB_DL = "https://github.com/Genymobile/scrcpy/releases/download/v{tag}/scrcpy-server-v{tag}"
_MIN_BYTES = 8_000
_PER_URL_ATTEMPTS = 3
_PER_URL_DELAY_S = 2.0


def _read_version(repo_root: Path) -> str:
    env = (os.environ.get("SCRCPY_SERVER_VERSION") or "").strip().lstrip("v")
    if env:
        return env
    vf = repo_root / "vendor" / "scrcpy-server.version"
    if vf.is_file():
        line = vf.read_text(encoding="utf-8").splitlines()[0].strip().lstrip("v")
        if line:
            return line
    return "3.3.3"


def _expand_download_url(template: str, tag: str) -> str:
    return template.replace("{tag}", tag).replace("{version}", tag)


def _download_urls_to_try(tag: str) -> list[str]:
    """顺序：SCRCPY_SERVER_DOWNLOAD_URL → SCRCPY_SERVER_DOWNLOAD_URLS →（默认可选）GitHub。"""
    urls: list[str] = []
    single = (os.environ.get("SCRCPY_SERVER_DOWNLOAD_URL") or "").strip()
    if single:
        urls.append(_expand_download_url(single, tag))
    raw = (os.environ.get("SCRCPY_SERVER_DOWNLOAD_URLS") or "").strip()
    if raw:
        for part in raw.split(","):
            u = part.strip()
            if not u:
                continue
            uu = _expand_download_url(u, tag)
            if uu not in urls:
                urls.append(uu)
    no_github = os.environ.get("SCRCPY_SERVER_DOWNLOAD_NO_GITHUB", "").strip().lower() in (
        "1",
        "true",
        "yes",
        "on",
    )
    gh = _GITHUB_DL.format(tag=tag)
    if not no_github and gh not in urls:
        urls.append(gh)
    seen: set[str] = set()
    out: list[str] = []
    for u in urls:
        if u not in seen:
            seen.add(u)
            out.append(u)
    return out


def _fetch_url(url: str) -> tuple[bool, bytes | None, str]:
    req = urllib.request.Request(
        url,
        headers={"User-Agent": "douyinyoutube-live-hub/scrcpy-bootstrap"},
        method="GET",
    )
    last_err = ""
    for attempt in range(1, _PER_URL_ATTEMPTS + 1):
        try:
            with urllib.request.urlopen(req, timeout=120) as resp:
                data = resp.read()
            return True, data, ""
        except (urllib.error.HTTPError, urllib.error.URLError, TimeoutError, OSError) as e:
            last_err = str(e)
            if attempt < _PER_URL_ATTEMPTS:
                time.sleep(_PER_URL_DELAY_S)
    return False, None, last_err


def ensure_scrcpy_jar(repo_root: Path) -> tuple[bool, str]:
    """
    若 vendor/scrcpy-server.jar 不存在或过小，则按 URL 列表下载。
    环境变量：
      SKIP_SCRCPY_SERVER_FETCH=1 — 跳过
      SCRCPY_SERVER_DOWNLOAD_URL — 优先下载地址，可用 {tag}/{version}
      SCRCPY_SERVER_DOWNLOAD_URLS — 逗号分隔多条，先于 GitHub
      SCRCPY_SERVER_DOWNLOAD_NO_GITHUB=1 — 仅用上面自定义 URL，不回退 GitHub
    """
    if os.environ.get("SKIP_SCRCPY_SERVER_FETCH", "").strip().lower() in ("1", "true", "yes", "on"):
        return True, "skip fetch (SKIP_SCRCPY_SERVER_FETCH)"

    vendor_dir = repo_root / "vendor"
    dest = vendor_dir / "scrcpy-server.jar"
    env_jar = (os.environ.get("SCRCPY_SERVER_JAR") or "").strip()
    if env_jar:
        p = Path(env_jar).expanduser()
        if p.is_file() and p.stat().st_size >= _MIN_BYTES:
            return True, "using SCRCPY_SERVER_JAR"

    if dest.is_file() and dest.stat().st_size >= _MIN_BYTES:
        return True, "vendor/scrcpy-server.jar ok"

    tag = _read_version(repo_root)
    urls = _download_urls_to_try(tag)
    if not urls:
        return False, "未配置任何下载源（SCRCPY_SERVER_DOWNLOAD_NO_GITHUB=1 且未设置 SCRCPY_SERVER_DOWNLOAD_URL(S)）"
    vendor_dir.mkdir(parents=True, exist_ok=True)
    tmp = dest.with_suffix(".jar.part")

    last_fail = ""
    for url in urls:
        ok, data, err = _fetch_url(url)
        if not ok or data is None:
            last_fail = f"{url}: {err}"
            continue
        if len(data) < _MIN_BYTES:
            last_fail = f"{url}: too small ({len(data)} bytes)"
            continue
        if not data.startswith(b"PK"):
            last_fail = f"{url}: not a JAR (missing PK header)"
            continue
        try:
            tmp.write_bytes(data)
            os.replace(tmp, dest)
        except OSError as e:
            return False, f"write vendor/scrcpy-server.jar failed: {e}"
        return True, f"fetched scrcpy-server v{tag} -> vendor/scrcpy-server.jar (via {url})"

    return False, f"download failed after {len(urls)} source(s): {last_fail}"


def main() -> int:
    root = Path(__file__).resolve().parent.parent
    ok, msg = ensure_scrcpy_jar(root)
    print(msg, file=sys.stderr if not ok else sys.stdout)
    return 0 if ok else 1


if __name__ == "__main__":
    raise SystemExit(main())