"""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 json
import secrets
from datetime import datetime, timezone, timedelta

from quart import (
    Blueprint,
    request,
    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, hash_token
from shared.infrastructure.urls import account_url, app_url
from shared.infrastructure.cart_identity import current_cart_identity
from shared.infrastructure.rate_limit import rate_limit, check_poll_backoff
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", "orders", "test", "artdag", "artdag_l2"}


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=None,
                    token_hash=hash_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=None,
                    code_hash=hash_token(code),
                    user_id=g.user.id,
                    client_id=client_id,
                    redirect_uri=redirect_uri,
                    expires_at=expires,
                    grant_token=None,
                    grant_token_hash=hash_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}&grant_token={grant_token}"
        )

    # --- 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)

        code_h = hash_token(code)
        async with get_session() as s:
            async with s.begin():
                # Look up by hash first (new grants), fall back to plaintext (migration)
                result = await s.execute(
                    select(OAuthCode)
                    .where(
                        (OAuthCode.code_hash == code_h) | (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

        token_h = hash_token(token)
        async with get_session() as s:
            grant = await s.scalar(
                select(OAuthGrant).where(
                    (OAuthGrant.token_hash == token_h) | (OAuthGrant.token == token)
                )
            )
            if not grant or grant.revoked_at is not None:
                return jsonify({"valid": False}), 200
            user = await s.get(User, grant.user_id)
            return jsonify({
                "valid": True,
                "user_id": grant.user_id,
                "username": user.email if user else "",
                "display_name": user.name if user else "",
            }), 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:
            import re
            # Validate cart_sid is a hex token (32 chars from token_hex(16))
            if re.fullmatch(r"[0-9a-f]{32}", cross_cart_sid):
                qsession["cart_sid"] = cross_cart_sid
        if g.get("user"):
            redirect_url = pop_login_redirect_target()
            return redirect(redirect_url)

        from shared.sx.page import get_template_context
        from sx.sx_components import render_login_page
        ctx = await get_template_context()
        return await render_login_page(ctx)

    @rate_limit(
        key_func=lambda: request.headers.get("X-Forwarded-For", request.remote_addr),
        max_requests=10, window_seconds=900, scope="magic_ip",
    )
    @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:
            from shared.sx.page import get_template_context
            from sx.sx_components import render_login_page
            ctx = await get_template_context(error="Please enter a valid email address.", email=email_input)
            return await render_login_page(ctx), 400

        # Per-email rate limit: 5 magic links per 15 minutes
        from shared.infrastructure.rate_limit import _check_rate_limit
        try:
            allowed, _ = await _check_rate_limit(f"magic_email:{email}", 5, 900)
            if not allowed:
                from shared.sx.page import get_template_context
                from sx.sx_components import render_check_email_page
                ctx = await get_template_context(email=email, email_error=None)
                return await render_check_email_page(ctx), 200
        except Exception:
            pass  # Redis down — allow the request

        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."
            )

        from shared.sx.page import get_template_context
        from sx.sx_components import render_check_email_page
        ctx = await get_template_context(email=email, email_error=email_error)
        return await render_check_email_page(ctx)

    @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:
                        from shared.sx.page import get_template_context
                        from sx.sx_components import render_login_page
                        ctx = await get_template_context(error=error)
                        return await render_login_page(ctx), 400
                    user_id = user.id

        except Exception:
            from shared.sx.page import get_template_context
            from sx.sx_components import render_login_page
            ctx = await get_template_context(error="Could not sign you in right now. Please try again.")
            return await render_login_page(ctx), 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.infrastructure.auth_redis import get_auth_redis
            import time as _time
            _auth_r = await get_auth_redis()
            await _auth_r.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.infrastructure.auth_redis import get_auth_redis
            _auth_r = await get_auth_redis()
            await _auth_r.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.infrastructure.auth_redis import get_auth_redis
            _auth_r = await get_auth_redis()
            await _auth_r.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

    # --- Device Authorization Flow (RFC 8628) ---------------------------------

    _DEVICE_ALPHABET = "ABCDEFGHJKMNPQRSTVWXYZ"
    _DEVICE_CODE_TTL = 900  # 15 minutes
    _DEVICE_POLL_INTERVAL = 5

    def _generate_user_code() -> str:
        """Generate an unambiguous 8-char user code like KBMN-TWRP."""
        chars = [secrets.choice(_DEVICE_ALPHABET) for _ in range(8)]
        return "".join(chars[:4]) + "-" + "".join(chars[4:])

    async def _approve_device(device_code: str, user) -> bool:
        """Approve a pending device flow and create an OAuthGrant."""
        from shared.infrastructure.auth_redis import get_auth_redis

        r = await get_auth_redis()
        raw = await r.get(f"devflow:{device_code}")
        if not raw:
            return False

        blob = json.loads(raw)
        if blob.get("status") != "pending":
            return False

        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)

        async with get_session() as s:
            async with s.begin():
                grant = OAuthGrant(
                    token=None,
                    token_hash=hash_token(grant_token),
                    user_id=user.id,
                    client_id=blob["client_id"],
                    issuer_session=account_sid,
                )
                s.add(grant)

        # Update Redis blob
        blob["status"] = "approved"
        blob["user_id"] = user.id
        blob["grant_token"] = grant_token
        user_code = blob["user_code"]

        ttl = await r.ttl(f"devflow:{device_code}")
        if ttl and ttl > 0:
            await r.set(f"devflow:{device_code}", json.dumps(blob).encode(), ex=ttl)
        else:
            await r.set(f"devflow:{device_code}", json.dumps(blob).encode(), ex=_DEVICE_CODE_TTL)

        # Remove reverse lookup (code already used)
        normalized_uc = user_code.replace("-", "").upper()
        await r.delete(f"devflow_uc:{normalized_uc}")

        return True

    @rate_limit(
        key_func=lambda: request.headers.get("X-Forwarded-For", request.remote_addr),
        max_requests=10, window_seconds=3600, scope="dev_auth",
    )
    @csrf_exempt
    @auth_bp.post("/device/authorize")
    @auth_bp.post("/device/authorize/")
    async def device_authorize():
        """RFC 8628 — CLI requests a device code."""
        data = await request.get_json(silent=True) or {}
        client_id = data.get("client_id", "")

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

        device_code = secrets.token_urlsafe(32)
        user_code = _generate_user_code()

        from shared.infrastructure.auth_redis import get_auth_redis

        r = await get_auth_redis()

        blob = json.dumps({
            "client_id": client_id,
            "user_code": user_code,
            "status": "pending",
            "user_id": None,
            "grant_token": None,
        }).encode()

        normalized_uc = user_code.replace("-", "").upper()
        pipe = r.pipeline()
        pipe.set(f"devflow:{device_code}", blob, ex=_DEVICE_CODE_TTL)
        pipe.set(f"devflow_uc:{normalized_uc}", device_code.encode(), ex=_DEVICE_CODE_TTL)
        await pipe.execute()

        verification_uri = account_url("/auth/device")

        return jsonify({
            "device_code": device_code,
            "user_code": user_code,
            "verification_uri": verification_uri,
            "expires_in": _DEVICE_CODE_TTL,
            "interval": _DEVICE_POLL_INTERVAL,
        })

    @csrf_exempt
    @auth_bp.post("/device/token")
    @auth_bp.post("/device/token/")
    async def device_token():
        """RFC 8628 — CLI polls for the grant token."""
        data = await request.get_json(silent=True) or {}
        device_code = data.get("device_code", "")
        client_id = data.get("client_id", "")

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

        # Enforce polling backoff per RFC 8628
        try:
            poll_ok, interval = await check_poll_backoff(device_code)
            if not poll_ok:
                return jsonify({"error": "slow_down", "interval": interval}), 400
        except Exception:
            pass  # Redis down — allow the request

        from shared.infrastructure.auth_redis import get_auth_redis

        r = await get_auth_redis()
        raw = await r.get(f"devflow:{device_code}")
        if not raw:
            return jsonify({"error": "expired_token"}), 400

        blob = json.loads(raw)

        if blob.get("client_id") != client_id:
            return jsonify({"error": "invalid_request"}), 400

        if blob["status"] == "pending":
            return jsonify({"error": "authorization_pending"}), 428

        if blob["status"] == "denied":
            return jsonify({"error": "access_denied"}), 400

        if blob["status"] == "approved":
            async with get_session() as s:
                user = await s.get(User, blob["user_id"])
                if not user:
                    return jsonify({"error": "access_denied"}), 400

            # Clean up Redis
            await r.delete(f"devflow:{device_code}")

            return jsonify({
                "access_token": blob["grant_token"],
                "token_type": "bearer",
                "user_id": blob["user_id"],
                "username": user.email or "",
                "display_name": user.name or "",
            })

        return jsonify({"error": "invalid_request"}), 400

    @auth_bp.get("/device")
    @auth_bp.get("/device/")
    async def device_form():
        """Browser form where user enters the code displayed in terminal."""
        from shared.sx.page import get_template_context
        from sx.sx_components import render_device_page
        code = request.args.get("code", "")
        ctx = await get_template_context(code=code)
        return await render_device_page(ctx)

    @auth_bp.post("/device")
    @auth_bp.post("/device/")
    async def device_submit():
        """Browser submit — validates code, approves if logged in."""
        form = await request.form
        user_code = (form.get("code") or "").strip().replace("-", "").upper()

        if not user_code or len(user_code) != 8:
            from shared.sx.page import get_template_context
            from sx.sx_components import render_device_page
            ctx = await get_template_context(error="Please enter a valid 8-character code.", code=form.get("code", ""))
            return await render_device_page(ctx), 400

        from shared.infrastructure.auth_redis import get_auth_redis

        r = await get_auth_redis()
        device_code = await r.get(f"devflow_uc:{user_code}")
        if not device_code:
            from shared.sx.page import get_template_context
            from sx.sx_components import render_device_page
            ctx = await get_template_context(error="Code not found or expired. Please try again.", code=form.get("code", ""))
            return await render_device_page(ctx), 400

        if isinstance(device_code, bytes):
            device_code = device_code.decode()

        # Not logged in — redirect to login, then come back to complete
        if not g.get("user"):
            complete_url = url_for("auth.device_complete", code=device_code)
            store_login_redirect_target()
            return redirect(url_for("auth.login_form", next=complete_url))

        # Logged in — approve immediately
        ok = await _approve_device(device_code, g.user)
        if not ok:
            from shared.sx.page import get_template_context
            from sx.sx_components import render_device_page
            ctx = await get_template_context(error="Code expired or already used.")
            return await render_device_page(ctx), 400

        from shared.sx.page import get_template_context
        from sx.sx_components import render_device_approved_page
        ctx = await get_template_context()
        return await render_device_approved_page(ctx)

    @auth_bp.get("/device/complete")
    @auth_bp.get("/device/complete/")
    async def device_complete():
        """Post-login redirect — completes approval after magic link auth."""
        from shared.sx.page import get_template_context
        from sx.sx_components import render_device_page, render_device_approved_page

        device_code = request.args.get("code", "")

        if not device_code:
            return redirect(url_for("auth.device_form"))

        if not g.get("user"):
            store_login_redirect_target()
            return redirect(url_for("auth.login_form"))

        ok = await _approve_device(device_code, g.user)
        if not ok:
            ctx = await get_template_context(
                error="Code expired or already used. Please start the login process again in your terminal.",
            )
            return await render_device_page(ctx), 400

        ctx = await get_template_context()
        return await render_device_approved_page(ctx)

    return auth_bp