"""OAuth + JWT auth routes (mounted at /api/auth and /api/me)."""
import os
from datetime import datetime, timedelta, timezone

from authlib.integrations.base_client import OAuthError
from fastapi import APIRouter, Depends, HTTPException, Request, status
from pydantic import BaseModel
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.auth import (
    create_access_token,
    email_domain_allowed,
    find_or_create_google_user,
    get_current_user,
    hash_refresh_token,
    issue_refresh_token,
    oauth,
)
from app.database import get_db
from app.models import (
    ActivityLog,
    DiscoveryConversation,
    DiscoveryProfile,
    RefreshToken,
    User,
)
from sqlalchemy import func

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


# -- response shapes ----------------------------------------------------------

class UserOut(BaseModel):
    id: str
    email: str
    display_name: str
    avatar_url: str | None = None
    role: str

    @classmethod
    def from_orm_user(cls, user: User) -> "UserOut":
        return cls(
            id=user.id,
            email=user.email,
            display_name=user.display_name,
            avatar_url=user.avatar_url,
            role=user.role,
        )


class TokenBundle(BaseModel):
    access_token: str
    refresh_token: str
    token_type: str = "bearer"
    user: UserOut


class RefreshIn(BaseModel):
    refresh_token: str


class AccessOut(BaseModel):
    access_token: str
    token_type: str = "bearer"


class DisplayNamePatch(BaseModel):
    display_name: str


class SessionOut(BaseModel):
    id: str
    device: str | None
    created_at: datetime
    expires_at: datetime


# -- OAuth flow ---------------------------------------------------------------


@router.get("/auth/login")
async def login(request: Request):
    """Kick off the OAuth dance: 302 to Google's consent screen."""
    redirect_uri = os.getenv("OAUTH_REDIRECT_URI") or str(
        request.url_for("auth_callback")
    )
    return await oauth.google.authorize_redirect(request, redirect_uri)


@router.get("/auth/callback", name="auth_callback")
async def auth_callback(request: Request, db: AsyncSession = Depends(get_db)):
    """Google redirects here with `code`; exchange it, mint our tokens."""
    try:
        token = await oauth.google.authorize_access_token(request)
    except OAuthError as exc:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"OAuth error: {exc.error or exc}",
        ) from exc

    user_info = token.get("userinfo")
    if not user_info or not user_info.get("email") or not user_info.get("sub"):
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="Google did not return email/sub",
        )
    if user_info.get("email_verified") is False:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Email not verified by Google",
        )
    if not email_domain_allowed(user_info["email"]):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Email domain not allowed",
        )

    user = await find_or_create_google_user(db, user_info)
    access = create_access_token(user.id, user.email)
    refresh = await issue_refresh_token(
        db, user, request.headers.get("user-agent")
    )
    return TokenBundle(
        access_token=access,
        refresh_token=refresh,
        user=UserOut.from_orm_user(user),
    )


@router.post("/auth/refresh", response_model=AccessOut)
async def refresh_access_token(
    body: RefreshIn, db: AsyncSession = Depends(get_db)
):
    stmt = select(RefreshToken).where(
        RefreshToken.token_hash == hash_refresh_token(body.refresh_token)
    )
    row = (await db.execute(stmt)).scalar_one_or_none()
    now = datetime.now(timezone.utc)
    if row is None or row.revoked_at is not None or _expired(row.expires_at, now):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Refresh token invalid or expired",
        )
    user = await db.get(User, row.user_id)
    if user is None:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="User no longer exists",
        )
    access = create_access_token(user.id, user.email)
    return AccessOut(access_token=access)


def _expired(expires_at: datetime, now: datetime) -> bool:
    # SQLite stores naive datetimes; compare in UTC.
    if expires_at.tzinfo is None:
        expires_at = expires_at.replace(tzinfo=timezone.utc)
    return expires_at < now


@router.post("/auth/logout")
async def logout(
    body: RefreshIn, db: AsyncSession = Depends(get_db)
):
    """Revoke a single refresh token. Idempotent — unknown token returns 200."""
    stmt = select(RefreshToken).where(
        RefreshToken.token_hash == hash_refresh_token(body.refresh_token)
    )
    row = (await db.execute(stmt)).scalar_one_or_none()
    if row is not None and row.revoked_at is None:
        row.revoked_at = datetime.now(timezone.utc)
        await db.commit()
    return {"status": "ok"}


# -- profile / sessions -------------------------------------------------------


@router.get("/auth/me", response_model=UserOut)
@router.get("/me", response_model=UserOut)
async def get_me(user: User = Depends(get_current_user)):
    return UserOut.from_orm_user(user)


@router.patch("/me", response_model=UserOut)
async def patch_me(
    body: DisplayNamePatch,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    new_name = body.display_name.strip()
    if not new_name:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="display_name cannot be empty",
        )
    user.display_name = new_name
    await db.commit()
    await db.refresh(user)
    return UserOut.from_orm_user(user)


class MeStats(BaseModel):
    conversations: int
    profiles: int
    locked_profiles: int
    activity_last_30d: int
    last_login_at: datetime | None


@router.get("/me/stats", response_model=MeStats)
async def my_stats(
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    convo_count = (await db.execute(
        select(func.count())
        .select_from(DiscoveryConversation)
        .where(DiscoveryConversation.user_id == user.id)
    )).scalar_one()
    profile_count = (await db.execute(
        select(func.count())
        .select_from(DiscoveryProfile)
        .where(DiscoveryProfile.user_id == user.id)
    )).scalar_one()
    locked_count = (await db.execute(
        select(func.count())
        .select_from(DiscoveryProfile)
        .where(DiscoveryProfile.user_id == user.id)
        .where(DiscoveryProfile.locked.is_(True))
    )).scalar_one()
    since = datetime.now(timezone.utc) - timedelta(days=30)
    activity_count = (await db.execute(
        select(func.count())
        .select_from(ActivityLog)
        .where(ActivityLog.user_id == user.id)
        .where(ActivityLog.created_at >= since)
    )).scalar_one()
    return MeStats(
        conversations=int(convo_count or 0),
        profiles=int(profile_count or 0),
        locked_profiles=int(locked_count or 0),
        activity_last_30d=int(activity_count or 0),
        last_login_at=user.last_login_at,
    )


@router.get("/me/sessions", response_model=list[SessionOut])
async def list_sessions(
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    stmt = (
        select(RefreshToken)
        .where(RefreshToken.user_id == user.id)
        .where(RefreshToken.revoked_at.is_(None))
        .order_by(RefreshToken.created_at.desc())
    )
    rows = (await db.execute(stmt)).scalars().all()
    return [
        SessionOut(
            id=r.id,
            device=r.device,
            created_at=r.created_at,
            expires_at=r.expires_at,
        )
        for r in rows
    ]


@router.delete("/me/sessions/{session_id}")
async def revoke_session(
    session_id: str,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    row = await db.get(RefreshToken, session_id)
    if row is None or row.user_id != user.id:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Session not found",
        )
    if row.revoked_at is None:
        row.revoked_at = datetime.now(timezone.utc)
        await db.commit()
    return {"status": "revoked"}