from fastapi import APIRouter, Depends, HTTPException, Request
from sqlalchemy import func, select
from sqlalchemy.orm import Session

from app.auth import current_user, has_read_scope, has_write_scope, is_allowed
from app.db import get_db
from app.models import Invite, User

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


@router.get("/accounts")
def my_accounts(
    request: Request,
    user: User = Depends(current_user),
    db: Session = Depends(get_db),
) -> list[dict]:
    """The accounts that have authenticated in this browser session (switchable without a
    new Google sign-in). The active one is flagged."""
    ids = request.session.get("account_ids") or [user.id]
    rows = {u.id: u for u in db.query(User).filter(User.id.in_(ids)).all()}
    out = []
    for uid in ids:  # preserve recency order from the session
        u = rows.get(uid)
        if u is not None:
            out.append(
                {
                    "id": u.id,
                    "email": u.email,
                    "display_name": u.display_name,
                    "avatar_url": u.avatar_url,
                    "active": u.id == user.id,
                }
            )
    return out


@router.post("/switch")
def switch_account(
    payload: dict,
    request: Request,
    user: User = Depends(current_user),
    db: Session = Depends(get_db),
) -> dict:
    """Switch the active account to another one already authenticated in this browser. No
    Google round-trip — but only accounts present in the session list (proof they signed in
    here) are allowed, and access is re-checked in case the invite was revoked since."""
    target = payload.get("user_id")
    if target not in (request.session.get("account_ids") or []):
        raise HTTPException(status_code=403, detail="Not an account you've signed into here.")
    u = db.get(User, target)
    if u is None:
        raise HTTPException(status_code=404, detail="That account no longer exists.")
    if not is_allowed(db, u.email):
        raise HTTPException(status_code=403, detail="That account no longer has access.")
    request.session["user_id"] = target
    return {"ok": True, "user_id": target}


@router.get("")
def get_me(
    user: User = Depends(current_user), db: Session = Depends(get_db)
) -> dict:
    pending_invites = 0
    if user.role == "admin":
        pending_invites = (
            db.scalar(
                select(func.count())
                .select_from(Invite)
                .where(Invite.status == "pending")
            )
            or 0
        )
    return {
        "id": user.id,
        "email": user.email,
        "display_name": user.display_name,
        "avatar_url": user.avatar_url,
        "role": user.role,
        "can_read": has_read_scope(user),
        "can_write": has_write_scope(user),
        "pending_invites": pending_invites,
        "preferences": user.preferences or {},
    }


@router.put("/preferences")
def update_preferences(
    preferences: dict,
    user: User = Depends(current_user),
    db: Session = Depends(get_db),
) -> dict:
    # Merge so partial updates don't wipe other keys.
    merged = dict(user.preferences or {})
    merged.update(preferences)
    user.preferences = merged
    db.add(user)
    db.commit()
    return {"preferences": merged}