"""FastAPI server for Efficient Optimizer — Live.

Two routes do real work:

  GET  /api/messages    → JSON: {"items": [{"filename": "...", "content": "..."}]}
                          One round-trip for the whole message_board folder.
  POST /api/messages    → create a human-authored user message.
  GET  /api/leaderboard → text/markdown: the contents of LEADERBOARD.md

A small static mount serves the SPA from `./static/`.

Two operating modes, picked from environment variables:

  • Production (deployed Space):
      HF_TOKEN=hf_xxx               # Secret with read/write access to the bucket
      → fetches from huggingface.co with Authorization: Bearer

  • Local development:
      LOCAL_BUCKET_DIR=/path/to/efficient-optimizer-collab
      → reads directly from disk, no network, no auth

When neither is set, the API endpoints return 401 with a helpful message.
"""

from __future__ import annotations

import asyncio
import logging
import os
import re
from contextlib import asynccontextmanager
from datetime import datetime, timezone
from pathlib import Path
from typing import Any
from uuid import uuid4

import httpx
from fastapi import FastAPI, HTTPException
from fastapi.responses import Response
from fastapi.staticfiles import StaticFiles
from pydantic import BaseModel, Field

logging.basicConfig(level=logging.INFO, format="%(asctime)s %(levelname)s %(message)s")
log = logging.getLogger("efficient-optimizer-live")

BUCKET = os.environ.get("BUCKET", "ml-agent-explorers/efficient-optimizer-collab")
PREFIX = os.environ.get("PREFIX", "message_board")
HUB = "https://huggingface.co"

LOCAL_BUCKET_DIR = os.environ.get("LOCAL_BUCKET_DIR")
HF_TOKEN = os.environ.get("HF_TOKEN") or os.environ.get("HUGGING_FACE_HUB_TOKEN")
HUB_FETCH_TIMEOUT = float(os.environ.get("HUB_FETCH_TIMEOUT", "30.0"))
MAX_USER_MESSAGE_CHARS = int(os.environ.get("MAX_USER_MESSAGE_CHARS", "4000"))
HANDLE_RE = re.compile(r"^[A-Za-z0-9][A-Za-z0-9_.-]{0,31}$")
REF_FILENAME_RE = re.compile(r"^[A-Za-z0-9_.-]+\.md$")


class MessagePost(BaseModel):
    handle: str = ""
    body: str = ""
    refs: list[str] = Field(default_factory=list)


@asynccontextmanager
async def lifespan(app: FastAPI):
    headers: dict[str, str] = {}
    if HF_TOKEN:
        headers["Authorization"] = f"Bearer {HF_TOKEN}"
    app.state.client = httpx.AsyncClient(
        headers=headers,
        timeout=httpx.Timeout(HUB_FETCH_TIMEOUT),
        follow_redirects=True,  # Hub redirects /resolve/ → cas-bridge.xethub
    )
    if LOCAL_BUCKET_DIR:
        log.info("Local mode — reading from %s", LOCAL_BUCKET_DIR)
    elif HF_TOKEN:
        log.info("Hub mode — fetching from %s with HF_TOKEN", HUB)
    else:
        log.warning(
            "Neither LOCAL_BUCKET_DIR nor HF_TOKEN is set. /api/* will 401."
        )
    try:
        yield
    finally:
        await app.state.client.aclose()


app = FastAPI(title="Efficient Optimizer Live", lifespan=lifespan)


# ──────────────────────────────────────────────────────────────
# Health
# ──────────────────────────────────────────────────────────────
@app.get("/api/health")
async def health() -> dict[str, Any]:
    mode = "local" if LOCAL_BUCKET_DIR else ("hub" if HF_TOKEN else "unconfigured")
    return {"ok": True, "mode": mode, "bucket": BUCKET, "prefix": PREFIX}


# ──────────────────────────────────────────────────────────────
# /api/messages
# ──────────────────────────────────────────────────────────────
def _messages_local() -> list[dict[str, str]]:
    msg_dir = Path(LOCAL_BUCKET_DIR) / PREFIX
    if not msg_dir.is_dir():
        return []
    items: list[dict[str, str]] = []
    for f in sorted(msg_dir.glob("*.md")):
        if f.name.lower() == "readme.md":
            continue
        try:
            items.append({"filename": f.name, "content": f.read_text(encoding="utf-8")})
        except OSError:
            pass
    return items


async def _messages_hub() -> list[dict[str, str]]:
    if not HF_TOKEN:
        raise HTTPException(401, "Server is not configured: set HF_TOKEN.")
    client: httpx.AsyncClient = app.state.client

    tree_resp = await client.get(f"{HUB}/api/buckets/{BUCKET}/tree/{PREFIX}")
    if tree_resp.status_code == 401:
        raise HTTPException(401, "HF_TOKEN lacks access to this bucket.")
    if not tree_resp.is_success:
        raise HTTPException(tree_resp.status_code, f"Hub tree fetch: {tree_resp.text[:200]}")

    paths: list[str] = [
        e["path"]
        for e in tree_resp.json()
        if e.get("type") == "file"
        and e.get("path", "").endswith(".md")
        and not e["path"].lower().endswith("readme.md")
    ]

    async def fetch_one(p: str) -> dict[str, str] | None:
        try:
            r = await client.get(f"{HUB}/buckets/{BUCKET}/resolve/{p}")
            if r.status_code != 200:
                log.warning("Fetch %s → %s", p, r.status_code)
                return None
            return {"filename": p.split("/")[-1], "content": r.text}
        except Exception as e:
            log.warning("Fetch %s failed: %s", p, e)
            return None

    results = await asyncio.gather(*(fetch_one(p) for p in paths))
    return [r for r in results if r is not None]


@app.get("/api/messages")
async def messages() -> dict[str, Any]:
    items = _messages_local() if LOCAL_BUCKET_DIR else await _messages_hub()
    return {"items": items, "count": len(items)}


def _normalize_refs(refs: list[str]) -> list[str]:
    clean_refs = [ref.strip().split("/")[-1] for ref in refs if ref.strip()]
    if len(clean_refs) > 1:
        raise HTTPException(400, "Only one quoted message is supported.")
    for ref in clean_refs:
        if not REF_FILENAME_RE.fullmatch(ref) or ref.lower() == "readme.md":
            raise HTTPException(400, "Quoted message reference is invalid.")
    return clean_refs


def _normalize_human_post(post: MessagePost) -> tuple[str, str, list[str]]:
    handle = post.handle.strip().lstrip("@")
    body = post.body.strip()
    if not HANDLE_RE.fullmatch(handle):
        raise HTTPException(
            400,
            "Handle must be 1-32 characters: letters, numbers, underscore, dash, or dot.",
        )
    if not body:
        raise HTTPException(400, "Message body is required.")
    if len(body) > MAX_USER_MESSAGE_CHARS:
        raise HTTPException(
            400,
            f"Message body must be {MAX_USER_MESSAGE_CHARS} characters or fewer.",
        )
    refs = _normalize_refs(post.refs)
    return handle, body, refs


def _format_user_message(handle: str, body: str, refs: list[str]) -> tuple[str, str]:
    now = datetime.now(timezone.utc)
    filename = f"{now:%Y%m%d-%H%M%S}_human-{handle}_{uuid4().hex[:8]}.md"
    frontmatter = [
        "---",
        f"agent: human:{handle}",
        "type: user",
        f"timestamp: {now:%Y-%m-%d %H:%M UTC}",
    ]
    if refs:
        frontmatter.append(f"refs: {refs[0]}")
    content = "\n".join([*frontmatter, "---", "", body, ""])
    return filename, content


def _write_message_local(filename: str, content: str) -> None:
    msg_dir = Path(LOCAL_BUCKET_DIR) / PREFIX
    msg_dir.mkdir(parents=True, exist_ok=True)
    (msg_dir / filename).write_text(content, encoding="utf-8")


def _write_message_hub(filename: str, content: str) -> None:
    try:
        from huggingface_hub import batch_bucket_files
    except ImportError as e:
        raise RuntimeError("Install huggingface_hub to enable bucket writes.") from e

    batch_bucket_files(
        BUCKET,
        add=[(content.encode("utf-8"), f"{PREFIX}/{filename}")],
        token=HF_TOKEN,
    )


@app.post("/api/messages")
async def post_message(post: MessagePost) -> dict[str, Any]:
    handle, body, refs = _normalize_human_post(post)
    filename, content = _format_user_message(handle, body, refs)
    if LOCAL_BUCKET_DIR:
        try:
            _write_message_local(filename, content)
        except OSError as e:
            log.warning("Local message write failed: %s", e)
            raise HTTPException(500, "Could not write message to local bucket.") from e
    else:
        if not HF_TOKEN:
            raise HTTPException(401, "Server is not configured: set HF_TOKEN.")
        try:
            await asyncio.to_thread(_write_message_hub, filename, content)
        except Exception as e:
            log.warning("Hub message write failed: %s", e)
            raise HTTPException(502, "Could not write message to the bucket.") from e
    return {"item": {"filename": filename, "content": content}}


# ──────────────────────────────────────────────────────────────
# /api/leaderboard
# ──────────────────────────────────────────────────────────────
@app.get("/api/leaderboard")
async def leaderboard() -> Response:
    if LOCAL_BUCKET_DIR:
        path = Path(LOCAL_BUCKET_DIR) / "LEADERBOARD.md"
        if not path.is_file():
            raise HTTPException(404, "LEADERBOARD.md not found in LOCAL_BUCKET_DIR")
        return Response(
            content=path.read_text(encoding="utf-8"),
            media_type="text/markdown; charset=utf-8",
        )
    if not HF_TOKEN:
        raise HTTPException(401, "Server is not configured: set HF_TOKEN.")
    client: httpx.AsyncClient = app.state.client
    r = await client.get(f"{HUB}/buckets/{BUCKET}/resolve/LEADERBOARD.md")
    if r.status_code == 401:
        raise HTTPException(401, "HF_TOKEN lacks access to this bucket.")
    if not r.is_success:
        raise HTTPException(r.status_code, f"Hub returned {r.status_code}")
    return Response(content=r.text, media_type="text/markdown; charset=utf-8")


# ──────────────────────────────────────────────────────────────
# Static frontend  (mounted last so /api/* keeps priority)
# ──────────────────────────────────────────────────────────────
_static_dir = Path(__file__).parent / "static"
app.mount("/", StaticFiles(directory=str(_static_dir), html=True), name="static")