"""Authentication routes for the account app.

Account is the OAuth authorization server. Owns magic link login/logout,
OAuth2 authorize endpoint, grant verification, and SSO logout.
"""
from __future__ import annotations

import secrets
from datetime import datetime, timezone, timedelta

from quart import (
    Blueprint,
    request,
    render_template,
    redirect,
    url_for,
    session as qsession,
    g,
    current_app,
    jsonify,
)
from sqlalchemy import select, update
from sqlalchemy.exc import SQLAlchemyError

from shared.db.session import get_session
from shared.models import User
from shared.models.oauth_code import OAuthCode
from shared.models.oauth_grant import OAuthGrant
from shared.infrastructure.urls import account_url, app_url
from shared.infrastructure.cart_identity import current_cart_identity
from shared.events import emit_activity

from .services import (
    pop_login_redirect_target,
    store_login_redirect_target,
    send_magic_email,
    find_or_create_user,
    create_magic_link,
    validate_magic_link,
    validate_email,
)

SESSION_USER_KEY = "uid"
ACCOUNT_SESSION_KEY = "account_sid"

ALLOWED_CLIENTS = {"blog", "market", "cart", "events", "federation", "artdag"}


def register(url_prefix="/auth"):
    auth_bp = Blueprint("auth", __name__, url_prefix=url_prefix)

    # --- OAuth2 authorize endpoint -------------------------------------------

    @auth_bp.get("/oauth/authorize")
    @auth_bp.get("/oauth/authorize/")
    async def oauth_authorize():
        client_id = request.args.get("client_id", "")
        redirect_uri = request.args.get("redirect_uri", "")
        state = request.args.get("state", "")
        device_id = request.args.get("device_id", "")
        prompt = request.args.get("prompt", "")

        if client_id not in ALLOWED_CLIENTS:
            return "Invalid client_id", 400

        expected_redirect = app_url(client_id, "/auth/callback")
        if redirect_uri != expected_redirect:
            return "Invalid redirect_uri", 400

        # Account's own device id — always available via factory hook
        account_did = g.device_id

        # Not logged in
        if not g.get("user"):
            if prompt == "none":
                # Silent check — pass account_did so client can watch for future logins
                sep = "&" if "?" in redirect_uri else "?"
                return redirect(
                    f"{redirect_uri}{sep}error=login_required"
                    f"&state={state}&account_did={account_did}"
                )
            authorize_path = request.full_path
            store_login_redirect_target()
            return redirect(url_for("auth.login_form", next=authorize_path))

        # Logged in — create grant + authorization code
        account_sid = qsession.get(ACCOUNT_SESSION_KEY)
        if not account_sid:
            account_sid = secrets.token_urlsafe(32)
            qsession[ACCOUNT_SESSION_KEY] = account_sid

        grant_token = secrets.token_urlsafe(48)
        code = secrets.token_urlsafe(48)
        now = datetime.now(timezone.utc)
        expires = now + timedelta(minutes=5)

        async with get_session() as s:
            async with s.begin():
                grant = OAuthGrant(
                    token=grant_token,
                    user_id=g.user.id,
                    client_id=client_id,
                    issuer_session=account_sid,
                    device_id=device_id or None,
                )
                s.add(grant)

                oauth_code = OAuthCode(
                    code=code,
                    user_id=g.user.id,
                    client_id=client_id,
                    redirect_uri=redirect_uri,
                    expires_at=expires,
                    grant_token=grant_token,
                )
                s.add(oauth_code)

        sep = "&" if "?" in redirect_uri else "?"
        return redirect(
            f"{redirect_uri}{sep}code={code}&state={state}"
            f"&account_did={account_did}"
        )

    # --- OAuth2 token exchange (for external clients like artdag) -------------

    from shared.browser.app.csrf import csrf_exempt

    @csrf_exempt
    @auth_bp.post("/oauth/token")
    @auth_bp.post("/oauth/token/")
    async def oauth_token():
        """Exchange an authorization code for user info + grant token.

        Used by clients that don't share the coop database (e.g. artdag).
        Accepts JSON: {code, client_id, redirect_uri}
        Returns JSON: {user_id, username, display_name, grant_token}
        """
        data = await request.get_json()
        if not data:
            return jsonify({"error": "invalid_request"}), 400

        code = data.get("code", "")
        client_id = data.get("client_id", "")
        redirect_uri = data.get("redirect_uri", "")

        if client_id not in ALLOWED_CLIENTS:
            return jsonify({"error": "invalid_client"}), 400

        now = datetime.now(timezone.utc)

        async with get_session() as s:
            async with s.begin():
                result = await s.execute(
                    select(OAuthCode)
                    .where(OAuthCode.code == code)
                    .with_for_update()
                )
                oauth_code = result.scalar_one_or_none()

                if not oauth_code:
                    return jsonify({"error": "invalid_grant"}), 400

                if oauth_code.used_at is not None:
                    return jsonify({"error": "invalid_grant"}), 400

                if oauth_code.expires_at < now:
                    return jsonify({"error": "invalid_grant"}), 400

                if oauth_code.client_id != client_id:
                    return jsonify({"error": "invalid_grant"}), 400

                if oauth_code.redirect_uri != redirect_uri:
                    return jsonify({"error": "invalid_grant"}), 400

                oauth_code.used_at = now
                user_id = oauth_code.user_id
                grant_token = oauth_code.grant_token

                user = await s.get(User, user_id)
                if not user:
                    return jsonify({"error": "invalid_grant"}), 400

                return jsonify({
                    "user_id": user_id,
                    "username": user.email or "",
                    "display_name": user.name or "",
                    "grant_token": grant_token,
                })

    # --- Grant verification (internal endpoint) ------------------------------

    @auth_bp.get("/internal/verify-grant")
    async def verify_grant():
        """Called by client apps to check if a grant is still valid."""
        token = request.args.get("token", "")
        if not token:
            return jsonify({"valid": False}), 200

        async with get_session() as s:
            grant = await s.scalar(
                select(OAuthGrant).where(OAuthGrant.token == token)
            )
            if not grant or grant.revoked_at is not None:
                return jsonify({"valid": False}), 200
            return jsonify({"valid": True}), 200

    @auth_bp.get("/internal/check-device")
    async def check_device():
        """Called by client apps to check if a device has an active auth.

        Looks up the most recent grant for (device_id, client_id).
        If the grant is active → {active: true}.
        If revoked but user has logged in since → {active: true} (re-auth needed).
        Otherwise → {active: false}.
        """
        device_id = request.args.get("device_id", "")
        app_name = request.args.get("app", "")
        if not device_id or not app_name:
            return jsonify({"active": False}), 200

        async with get_session() as s:
            # Find the most recent grant for this device + app
            result = await s.execute(
                select(OAuthGrant)
                .where(OAuthGrant.device_id == device_id)
                .where(OAuthGrant.client_id == app_name)
                .order_by(OAuthGrant.created_at.desc())
                .limit(1)
            )
            grant = result.scalar_one_or_none()

            if not grant:
                return jsonify({"active": False}), 200

            # Grant still active
            if grant.revoked_at is None:
                return jsonify({"active": True}), 200

            # Grant revoked — check if user logged in since
            user = await s.get(User, grant.user_id)
            if user and user.last_login_at and user.last_login_at > grant.revoked_at:
                return jsonify({"active": True}), 200

            return jsonify({"active": False}), 200

    # --- Magic link login flow -----------------------------------------------

    @auth_bp.get("/login/")
    async def login_form():
        store_login_redirect_target()
        cross_cart_sid = request.args.get("cart_sid")
        if cross_cart_sid:
            qsession["cart_sid"] = cross_cart_sid
        if g.get("user"):
            redirect_url = pop_login_redirect_target()
            return redirect(redirect_url)
        return await render_template("auth/login.html")

    @auth_bp.post("/start/")
    async def start_login():
        form = await request.form
        email_input = form.get("email") or ""

        is_valid, email = validate_email(email_input)
        if not is_valid:
            return (
                await render_template(
                    "auth/login.html",
                    error="Please enter a valid email address.",
                    email=email_input,
                ),
                400,
            )

        user = await find_or_create_user(g.s, email)
        token, expires = await create_magic_link(g.s, user.id)

        from shared.utils import host_url
        magic_url = host_url(url_for("auth.magic", token=token))

        email_error = None
        try:
            await send_magic_email(email, magic_url)
        except Exception as e:
            current_app.logger.error("EMAIL SEND FAILED: %r", e)
            email_error = (
                "We couldn't send the email automatically. "
                "Please try again in a moment."
            )

        return await render_template(
            "auth/check_email.html",
            email=email,
            email_error=email_error,
        )

    @auth_bp.get("/magic/<token>/")
    async def magic(token: str):
        now = datetime.now(timezone.utc)
        user_id: int | None = None

        try:
            async with get_session() as s:
                async with s.begin():
                    user, error = await validate_magic_link(s, token)

                    if error:
                        return (
                            await render_template("auth/login.html", error=error),
                            400,
                        )
                    user_id = user.id

        except Exception:
            return (
                await render_template(
                    "auth/login.html",
                    error="Could not sign you in right now. Please try again.",
                ),
                502,
            )

        assert user_id is not None

        ident = current_cart_identity()
        anon_session_id = ident.get("session_id")

        try:
            async with get_session() as s:
                async with s.begin():
                    u2 = await s.get(User, user_id)
                    if u2:
                        u2.last_login_at = now
                    if anon_session_id:
                        await emit_activity(
                            s,
                            activity_type="rose:Login",
                            actor_uri="internal:system",
                            object_type="Person",
                            object_data={
                                "user_id": user_id,
                                "session_id": anon_session_id,
                            },
                        )
                    # Notify external services of device login
                    await emit_activity(
                        s,
                        activity_type="rose:DeviceAuth",
                        actor_uri="internal:system",
                        object_type="Device",
                        object_data={
                            "device_id": g.device_id,
                            "action": "login",
                        },
                    )
        except SQLAlchemyError:
            current_app.logger.exception(
                "[auth] non-fatal DB update for user_id=%s", user_id
            )

        qsession[SESSION_USER_KEY] = user_id
        # Fresh account session ID for grant tracking
        qsession[ACCOUNT_SESSION_KEY] = secrets.token_urlsafe(32)

        # Signal login for this device so client apps can detect it
        try:
            from shared.browser.app.redis_cacher import get_redis
            import time as _time
            _redis = get_redis()
            if _redis:
                await _redis.set(
                    f"did_auth:{g.device_id}",
                    str(_time.time()).encode(),
                    ex=30 * 24 * 3600,
                )
        except Exception:
            current_app.logger.exception("[auth] failed to set did_auth in Redis")

        redirect_url = pop_login_redirect_target()
        return redirect(redirect_url, 303)

    @auth_bp.post("/logout/")
    async def logout():
        # Revoke all grants issued by this account session
        account_sid = qsession.get(ACCOUNT_SESSION_KEY)
        if account_sid:
            try:
                async with get_session() as s:
                    async with s.begin():
                        await s.execute(
                            update(OAuthGrant)
                            .where(OAuthGrant.issuer_session == account_sid)
                            .where(OAuthGrant.revoked_at.is_(None))
                            .values(revoked_at=datetime.now(timezone.utc))
                        )
            except SQLAlchemyError:
                current_app.logger.exception("[auth] failed to revoke grants")

        # Clear login signal for this device
        try:
            from shared.browser.app.redis_cacher import get_redis
            _redis = get_redis()
            if _redis:
                await _redis.delete(f"did_auth:{g.device_id}")
        except Exception:
            pass

        # Notify external services of device logout
        try:
            async with get_session() as s:
                async with s.begin():
                    await emit_activity(
                        s,
                        activity_type="rose:DeviceAuth",
                        actor_uri="internal:system",
                        object_type="Device",
                        object_data={
                            "device_id": g.device_id,
                            "action": "logout",
                        },
                    )
        except Exception:
            current_app.logger.exception("[auth] failed to emit DeviceAuth logout")

        qsession.pop(SESSION_USER_KEY, None)
        qsession.pop(ACCOUNT_SESSION_KEY, None)
        from shared.infrastructure.urls import blog_url
        return redirect(blog_url("/"))

    @auth_bp.get("/sso-logout/")
    async def sso_logout():
        """SSO logout called by client apps: revoke grants, clear session."""
        account_sid = qsession.get(ACCOUNT_SESSION_KEY)
        if account_sid:
            try:
                async with get_session() as s:
                    async with s.begin():
                        await s.execute(
                            update(OAuthGrant)
                            .where(OAuthGrant.issuer_session == account_sid)
                            .where(OAuthGrant.revoked_at.is_(None))
                            .values(revoked_at=datetime.now(timezone.utc))
                        )
            except SQLAlchemyError:
                current_app.logger.exception("[auth] failed to revoke grants")

        # Clear login signal for this device
        try:
            from shared.browser.app.redis_cacher import get_redis
            _redis = get_redis()
            if _redis:
                await _redis.delete(f"did_auth:{g.device_id}")
        except Exception:
            pass

        # Notify external services of device logout
        try:
            async with get_session() as s:
                async with s.begin():
                    await emit_activity(
                        s,
                        activity_type="rose:DeviceAuth",
                        actor_uri="internal:system",
                        object_type="Device",
                        object_data={
                            "device_id": g.device_id,
                            "action": "logout",
                        },
                    )
        except Exception:
            current_app.logger.exception("[auth] failed to emit DeviceAuth logout")

        qsession.pop(SESSION_USER_KEY, None)
        qsession.pop(ACCOUNT_SESSION_KEY, None)
        from shared.infrastructure.urls import blog_url
        return redirect(blog_url("/"))

    @auth_bp.get("/clear/")
    async def clear():
        """One-time migration helper: clear all session cookies."""
        qsession.clear()
        resp = redirect(account_url("/"))
        resp.delete_cookie("blog_session", domain=".rose-ash.com", path="/")
        return resp

    return auth_bp