from fastapi import APIRouter, HTTPException, Depends
from pydantic import BaseModel
from typing import Optional
import structlog
import time

from auth import get_db, get_current_user

logger = structlog.get_logger(__name__)

router = APIRouter(prefix="/api", tags=["friends"])

def init_friends_db():
    with get_db() as conn:
        conn.executescript("""
            CREATE TABLE IF NOT EXISTS friendships (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                requester_id INTEGER NOT NULL,
                target_id INTEGER NOT NULL,
                status TEXT NOT NULL DEFAULT 'pending',
                created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
                UNIQUE(requester_id, target_id),
                FOREIGN KEY (requester_id) REFERENCES users(id),
                FOREIGN KEY (target_id) REFERENCES users(id)
            );
            CREATE TABLE IF NOT EXISTS user_status (
                user_id INTEGER PRIMARY KEY,
                is_online INTEGER DEFAULT 0,
                current_pack TEXT DEFAULT '',
                last_seen TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
                FOREIGN KEY (user_id) REFERENCES users(id)
            );
            CREATE INDEX IF NOT EXISTS idx_friendships_requester ON friendships(requester_id);
            CREATE INDEX IF NOT EXISTS idx_friendships_target ON friendships(target_id);
        """)

class AddFriendRequest(BaseModel):
    username: str

class RemoveFriendRequest(BaseModel):
    user_id: int

class AcceptFriendRequest(BaseModel):
    user_id: int

class StatusUpdateRequest(BaseModel):
    online: bool = True
    current_pack: Optional[str] = None

@router.post("/friends/add")
async def add_friend(
    req: AddFriendRequest,
    current_user: dict = Depends(get_current_user)
):
    with get_db() as conn:
        cursor = conn.execute("SELECT id FROM users WHERE username = ?", (req.username,))
        target = cursor.fetchone()
        if not target:
            raise HTTPException(404, "User not found")
        target_id = target[0]

        if target_id == current_user["id"]:
            raise HTTPException(400, "Cannot add yourself")

        cursor = conn.execute(
            "SELECT status FROM friendships WHERE requester_id = ? AND target_id = ?",
            (current_user["id"], target_id)
        )
        existing = cursor.fetchone()
        if existing:
            if existing[0] == "accepted":
                raise HTTPException(400, "Already friends")
            raise HTTPException(400, f"Friend request already {existing[0]}")

        conn.execute(
            "INSERT INTO friendships (requester_id, target_id, status) VALUES (?, ?, 'pending')",
            (current_user["id"], target_id)
        )
        logger.info("Friend request sent", from_user=current_user["id"], to_user=target_id)
        return {"message": "Friend request sent"}

@router.post("/friends/accept")
async def accept_friend(
    req: AcceptFriendRequest,
    current_user: dict = Depends(get_current_user)
):
    with get_db() as conn:
        cursor = conn.execute(
            "SELECT id, requester_id FROM friendships WHERE target_id = ? AND requester_id = ? AND status = 'pending'",
            (current_user["id"], req.user_id)
        )
        row = cursor.fetchone()
        if not row:
            raise HTTPException(404, "No pending friend request from this user")
        conn.execute("UPDATE friendships SET status = 'accepted' WHERE id = ?", (row[0],))
        logger.info("Friend request accepted", from_user=req.user_id, to_user=current_user["id"])
        return {"message": "Friend request accepted"}

@router.post("/friends/remove")
async def remove_friend(
    req: RemoveFriendRequest,
    current_user: dict = Depends(get_current_user)
):
    with get_db() as conn:
        cursor = conn.execute(
            "SELECT id FROM friendships WHERE (requester_id = ? AND target_id = ?) OR (requester_id = ? AND target_id = ?)",
            (current_user["id"], req.user_id, req.user_id, current_user["id"])
        )
        row = cursor.fetchone()
        if not row:
            raise HTTPException(404, "Not friends")
        conn.execute("DELETE FROM friendships WHERE id = ?", (row[0],))
        logger.info("Friend removed", user=current_user["id"], target=req.user_id)
        return {"message": "Friend removed"}

@router.get("/friends/list")
async def list_friends(current_user: dict = Depends(get_current_user)):
    friends = []
    with get_db() as conn:
        rows = conn.execute("""
            SELECT u.id, u.username, u.role,
                   COALESCE(us.is_online, 0) as online,
                   COALESCE(us.current_pack, '') as current_pack,
                   us.last_seen
            FROM friendships f
            JOIN users u ON (CASE WHEN f.requester_id = ? THEN f.target_id ELSE f.requester_id END) = u.id
            LEFT JOIN user_status us ON u.id = us.user_id
            WHERE (f.requester_id = ? OR f.target_id = ?) AND f.status = 'accepted'
        """, (current_user["id"], current_user["id"], current_user["id"]))

        for row in rows:
            friends.append({
                "id": row[0],
                "username": row[1],
                "role": row[2],
                "online": bool(row[3]),
                "current_pack": row[4],
                "last_seen": row[5].isoformat() if row[5] else None
            })

    return {"friends": friends}

@router.get("/friends/requests")
async def list_friend_requests(current_user: dict = Depends(get_current_user)):
    requests = []
    with get_db() as conn:
        rows = conn.execute("""
            SELECT u.id, u.username, u.role, f.created_at
            FROM friendships f
            JOIN users u ON f.requester_id = u.id
            WHERE f.target_id = ? AND f.status = 'pending'
        """, (current_user["id"],))
        for row in rows:
            requests.append({
                "id": row[0],
                "username": row[1],
                "role": row[2],
                "created_at": row[3].isoformat() if row[3] else None
            })
    return {"requests": requests}

@router.post("/friends/status")
async def update_status(
    req: StatusUpdateRequest,
    current_user: dict = Depends(get_current_user)
):
    with get_db() as conn:
        conn.execute("""
            INSERT INTO user_status (user_id, is_online, current_pack, last_seen)
            VALUES (?, ?, ?, CURRENT_TIMESTAMP)
            ON CONFLICT(user_id) DO UPDATE SET
                is_online = excluded.is_online,
                current_pack = COALESCE(excluded.current_pack, user_status.current_pack),
                last_seen = CURRENT_TIMESTAMP
        """, (current_user["id"], int(req.online), req.current_pack or ""))
    return {"status": "ok"}