from fastapi import FastAPI, HTTPException, Depends
from fastapi.staticfiles import StaticFiles
from pydantic import BaseModel
from typing import Optional
import hashlib
import secrets
import os
import threading
import time as _time

from backend.database import get_db, init_db, log_audit
from backend.auth import get_current_user, require_role, require_login

app = FastAPI(title="App API")


# ── Periodic WAL checkpoint ───────────────────────────
def _wal_checkpoint_loop():
    while True:
        _time.sleep(300)
        try:
            conn = get_db()
            conn.execute("PRAGMA wal_checkpoint(TRUNCATE)")
            conn.close()
        except:
            pass

threading.Thread(target=_wal_checkpoint_loop, daemon=True).start()


# ── Models ────────────────────────────────────────────
class LoginRequest(BaseModel):
    username: str
    password: str

class RegisterRequest(BaseModel):
    username: str
    password: str
    display_name: str = ""


# ── Health & Version ──────────────────────────────────
APP_VERSION = "0.1.0"

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

@app.get("/api/version")
def version():
    return {"version": APP_VERSION}


# ── Auth endpoints ────────────────────────────────────
def _hash_password(pw: str) -> str:
    return hashlib.sha256(pw.encode()).hexdigest()

@app.get("/api/me")
def get_me(user=Depends(get_current_user)):
    return {
        "id": user.get("id"),
        "username": user["username"],
        "role": user["role"],
        "display_name": user.get("display_name", ""),
    }

@app.post("/api/login")
def login(body: LoginRequest):
    conn = get_db()
    user = conn.execute(
        "SELECT id, username, token, password, role, display_name FROM users WHERE username = ?",
        (body.username,),
    ).fetchone()
    conn.close()
    if not user:
        raise HTTPException(401, "用户名或密码错误")
    user = dict(user)
    if user.get("password") and user["password"] != _hash_password(body.password):
        raise HTTPException(401, "用户名或密码错误")
    return {"token": user["token"]}

@app.post("/api/register", status_code=201)
def register(body: RegisterRequest):
    conn = get_db()
    existing = conn.execute("SELECT id FROM users WHERE username = ?", (body.username,)).fetchone()
    if existing:
        conn.close()
        raise HTTPException(409, "用户名已存在")
    token = secrets.token_hex(24)
    pw_hash = _hash_password(body.password)
    conn.execute(
        "INSERT INTO users (username, password, token, role, display_name) VALUES (?, ?, ?, ?, ?)",
        (body.username, pw_hash, token, "viewer", body.display_name or body.username),
    )
    conn.commit()
    conn.close()
    return {"token": token}


# ── User management (admin) ──────────────────────────
@app.get("/api/users")
def list_users(user=Depends(require_role("admin"))):
    conn = get_db()
    rows = conn.execute("SELECT id, username, role, display_name, token, created_at FROM users ORDER BY id").fetchall()
    conn.close()
    return [dict(r) for r in rows]


# ── Static files (frontend) ──────────────────────────
@app.on_event("startup")
def on_startup():
    init_db()
    frontend_dir = os.environ.get("FRONTEND_DIR", "frontend/dist")
    if os.path.isdir(frontend_dir):
        app.mount("/", StaticFiles(directory=frontend_dir, html=True), name="frontend")