deer-flow/backend/app/gateway/routers/auth.py

"""Authentication endpoints."""

import asyncio
import logging
import os
import re
import socket
import time
import urllib.parse
from ipaddress import ip_address, ip_network

from fastapi import APIRouter, Depends, Form, HTTPException, Request, Response, status
from fastapi.security import OAuth2PasswordRequestForm
from pydantic import BaseModel, EmailStr, Field, field_validator
from starlette.responses import RedirectResponse

from app.gateway.auth import (
    UserResponse,
    create_access_token,
    login_throttle,
)
from app.gateway.auth.config import get_auth_config
from app.gateway.auth.errors import AuthErrorCode, AuthErrorResponse
from app.gateway.auth.oidc import OIDCError, OIDCService
from app.gateway.auth.oidc_state import (
    OIDCStatePayload,
    compute_code_challenge,
    delete_state_cookie,
    generate_code_verifier,
    generate_nonce,
    generate_oidc_state,
    get_state_cookie,
    set_state_cookie,
)
from app.gateway.auth.pat import PAT_MAX_NAME_LENGTH
from app.gateway.auth.session_cookie import ACCESS_TOKEN_COOKIE_NAME, SESSION_PERSISTENCE_COOKIE_NAME, set_session_cookie
from app.gateway.auth.session_cookie_state import SKIP_AUTH_CSRF_COOKIE_STATE_ATTR
from app.gateway.auth.user_provisioning import get_or_provision_oidc_user
from app.gateway.csrf_middleware import CSRF_COOKIE_NAME, _request_origin, auth_csrf_cookie_settings, generate_csrf_token, is_secure_request
from app.gateway.deps import get_current_user_from_request, get_local_provider
from app.gateway.utils import constant_time_equals
from deerflow.config.auth_config import OIDCAuthConfig, OIDCProviderConfig
from deerflow.persistence.login_throttle import LoginThrottleStore

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/api/v1/auth", tags=["auth"])


# ── Request/Response Models ──────────────────────────────────────────────


class LoginResponse(BaseModel):
    """Response model for login — token only lives in HttpOnly cookie."""

    expires_in: int  # seconds
    needs_setup: bool = False


# Top common-password blocklist. Drawn from the public SecLists "10k worst
# passwords" set, lowercased + length>=8 only (shorter ones already fail
# the min_length check). Kept tight on purpose: this is the **lower bound**
# defense, not a full HIBP / passlib check, and runs in-process per request.
_COMMON_PASSWORDS: frozenset[str] = frozenset(
    {
        "password",
        "password1",
        "password12",
        "password123",
        "password1234",
        "12345678",
        "123456789",
        "1234567890",
        "qwerty12",
        "qwertyui",
        "qwerty123",
        "abc12345",
        "abcd1234",
        "iloveyou",
        "letmein1",
        "welcome1",
        "welcome123",
        "admin123",
        "administrator",
        "passw0rd",
        "p@ssw0rd",
        "monkey12",
        "trustno1",
        "sunshine",
        "princess",
        "football",
        "baseball",
        "superman",
        "batman123",
        "starwars",
        "dragon123",
        "master123",
        "shadow12",
        "michael1",
        "jennifer",
        "computer",
    }
)


def _password_is_common(password: str) -> bool:
    """Case-insensitive blocklist check.

    Lowercases the input so trivial mutations like ``Password`` /
    ``PASSWORD`` are also rejected. Does not normalize digit substitutions
    (``p@ssw0rd`` is included as a literal entry instead) — keeping the
    rule cheap and predictable.
    """
    return password.lower() in _COMMON_PASSWORDS


def _validate_strong_password(value: str) -> str:
    """Pydantic field-validator body shared by Register + ChangePassword.

    Constraint = function, not type-level mixin. The two request models
    have no "is-a" relationship; they only share the password-strength
    rule. Lifting it into a free function lets each model bind it via
    ``@field_validator(field_name)`` without inheritance gymnastics.
    """
    if _password_is_common(value):
        raise ValueError("Password is too common; choose a stronger password.")
    return value


class RegisterRequest(BaseModel):
    """Request model for user registration."""

    email: EmailStr
    password: str = Field(..., min_length=8)
    remember_me: bool = True

    _strong_password = field_validator("password")(classmethod(lambda cls, v: _validate_strong_password(v)))


class ChangePasswordRequest(BaseModel):
    """Request model for password change (also handles setup flow)."""

    current_password: str
    new_password: str = Field(..., min_length=8)
    new_email: EmailStr | None = None
    remember_me: bool | None = None

    _strong_password = field_validator("new_password")(classmethod(lambda cls, v: _validate_strong_password(v)))


class MessageResponse(BaseModel):
    """Generic message response."""

    message: str


# ── Helpers ───────────────────────────────────────────────────────────────


def _set_session_cookie(response: Response, token: str, request: Request, *, remember_me: bool | None = None) -> None:
    """Set the access_token HttpOnly cookie on the response."""
    set_session_cookie(response, request, token, remember_me=remember_me)


# ── Rate Limiting ────────────────────────────────────────────────────────
# Failed logins are counted per client IP in a ``LoginThrottleStore``
# (``deerflow.persistence.login_throttle``). The store is resolved once per
# process by ``app.gateway.auth.login_throttle`` — the Gateway lifespan
# installs it from the startup config and the persistence engine, a bare app
# resolves it lazily on the first throttle call — and ``auth.local.
# throttle_storage`` picks the implementation: the shared ``login_throttle``
# table whenever an application database exists (every replica sharing that
# database enforces one lockout per IP), otherwise the historical in-process
# counter (per process: N replicas give an attacker N × max_login_attempts
# guesses; ``deps._validate_login_throttle_storage`` warns about that).
#
# The policy values are operator-configurable via auth.local.max_login_attempts /
# auth.local.lockout_seconds (read live per call, matching _local_registration_enabled,
# so a config reload applies to the next login without a Gateway restart). The
# no-config.yaml fallback is the LocalAuthConfig model defaults — a single source
# of truth, not a second copy of the numbers.
#
# A lock's stored duration always matches the policy the lock was last
# evaluated under (its creation counts as an evaluation, and every check that
# leaves the lock active commits the then-current duration, decreases
# included): a lowered lockout_seconds releases an active lock early, a raised
# one extends it — and a sentence that already served the last-evaluated
# duration is never resurrected. The stores implement that contract
# (``deerflow/persistence/login_throttle/base.py``); this module only sequences
# the calls and keeps the config read off the event loop.


async def _login_throttle_store() -> LoginThrottleStore:
    """The process-wide store, resolving it off the loop on first use in a bare app."""
    store = login_throttle.installed_login_throttle_store()
    if store is None:
        # Resolution reads config.yaml (stat + hash); never on the loop.
        store = await asyncio.to_thread(login_throttle.resolve_and_install_from_live_config)
    return store


def _login_throttle_policy() -> tuple[int, float]:
    """(max_login_attempts, lockout_seconds) from auth.local config, read live.

    Only ``FileNotFoundError`` falls back to the model defaults, matching
    ``_local_registration_enabled``: ``config.yaml`` is absent in bare-app
    contexts that never load it (tests build the gateway without one), and the
    throttle must keep its pre-config-era behavior there. A malformed config
    propagates instead — like every other config consumer, and so an operator
    who tightened the policy never silently gets the more permissive defaults.

    Callers on request paths resolve this at most once per helper invocation;
    ``get_app_config`` re-hashes the config file on every call, and the login
    endpoint is unauthenticated.
    """
    from deerflow.config.app_config import get_app_config
    from deerflow.config.auth_config import LocalAuthConfig

    try:
        local = get_app_config().auth.local
    except FileNotFoundError:
        local = LocalAuthConfig()
    return local.max_login_attempts, local.lockout_seconds


# Hostname entries (e.g. the compose service ``nginx``) are re-resolved at most
# this often: a restarted proxy container comes back on a new address, and
# nginx's own resolver uses the same validity (docker/nginx/nginx.conf).
_TRUSTED_PROXY_HOST_TTL_SECONDS = 10.0
_HOSTNAME_LABEL = re.compile(r"[A-Za-z0-9](?:[A-Za-z0-9-]{0,61}[A-Za-z0-9])?")
# hostname -> (monotonic expiry, resolved addresses). Failed lookups are cached
# as an empty set too, so unauthenticated requests cannot drive a lookup storm.
_trusted_proxy_host_cache: dict[str, tuple[float, frozenset]] = {}
# hostname -> the lookup in progress. Concurrent cache misses (a burst of
# setup-status / login requests when the entry expires) join it, so a refresh
# costs one resolver call however many requests arrive while DNS is slow.
_trusted_proxy_host_inflight: dict[str, asyncio.Task[frozenset]] = {}


def _is_hostname(entry: str) -> bool:
    """RFC 1123 hostname whose last label is not numeric (so ``10.0.0`` is not one)."""
    labels = entry.split(".")
    return len(entry) <= 253 and all(_HOSTNAME_LABEL.fullmatch(label) for label in labels) and not labels[-1].isdigit()


def _trusted_proxies() -> tuple[list, list[str]]:
    """Parse ``AUTH_TRUSTED_PROXIES`` into (ip_network objects, hostnames).

    Comma-separated CIDR, single-IP or hostname entries. Empty / unset = no
    proxy is trusted (direct mode). A hostname stands for every address it
    resolves to, so a proxy without a fixed address (the compose ``nginx``
    service) can still be named. Invalid entries are skipped with a logger
    warning. The variable is read live so env-var overrides take effect
    immediately and tests can ``monkeypatch.setenv``; only the addresses a
    hostname resolves to are cached (``_trusted_proxy_host_addresses``).
    """
    raw = os.getenv("AUTH_TRUSTED_PROXIES", "").strip()
    if not raw:
        return [], []
    nets = []
    hostnames = []
    for entry in raw.split(","):
        entry = entry.strip()
        if not entry:
            continue
        try:
            nets.append(ip_network(entry, strict=False))
        except ValueError:
            if _is_hostname(entry):
                hostnames.append(entry)
            else:
                logger.warning("AUTH_TRUSTED_PROXIES: ignoring invalid entry %r", entry)
    return nets, hostnames


async def _resolve_trusted_proxy_host(hostname: str) -> frozenset:
    """Resolve ``hostname`` in the loop's executor and cache the result (or the failure)."""
    try:
        infos = await asyncio.get_running_loop().getaddrinfo(hostname, None, type=socket.SOCK_STREAM)
        addresses = frozenset(ip_address(info[4][0]) for info in infos)
    except (OSError, ValueError) as exc:
        logger.warning("AUTH_TRUSTED_PROXIES: could not resolve %r (%s); not trusting it for %.0fs", hostname, exc, _TRUSTED_PROXY_HOST_TTL_SECONDS)
        addresses = frozenset()
    _trusted_proxy_host_cache[hostname] = (time.monotonic() + _TRUSTED_PROXY_HOST_TTL_SECONDS, addresses)
    return addresses


async def _trusted_proxy_host_addresses(hostname: str) -> frozenset:
    """Addresses ``hostname`` resolves to, cached for ``_TRUSTED_PROXY_HOST_TTL_SECONDS``.

    The lookup runs in the loop's executor (``getaddrinfo`` blocks). A failed
    lookup trusts nothing until the entry expires, which is the direct-mode
    behavior, not an error for the request. One lookup per hostname runs at a
    time: the cache check and the in-flight registration happen without a
    yield in between, and later callers join that task. Callers wait through
    ``asyncio.shield``, so one cancelled request (a client disconnect) cannot
    cancel the lookup the others joined; the task caches its own result, so
    it is kept even if every caller went away.
    """
    cached = _trusted_proxy_host_cache.get(hostname)
    if cached is not None and time.monotonic() < cached[0]:
        return cached[1]
    task = _trusted_proxy_host_inflight.get(hostname)
    if task is None:
        task = asyncio.get_running_loop().create_task(_resolve_trusted_proxy_host(hostname))
        _trusted_proxy_host_inflight[hostname] = task

        def _release(done: asyncio.Task[frozenset]) -> None:
            if _trusted_proxy_host_inflight.get(hostname) is done:
                del _trusted_proxy_host_inflight[hostname]

        task.add_done_callback(_release)
    return await asyncio.shield(task)


async def _is_trusted_proxy(peer_ip) -> bool:
    nets, hostnames = _trusted_proxies()
    if any(peer_ip in net for net in nets):
        return True
    for hostname in hostnames:
        if peer_ip in await _trusted_proxy_host_addresses(hostname):
            return True
    return False


async def _get_client_ip(request: Request) -> str:
    """Extract the real client IP for rate limiting.

    Trust model:

    - The TCP peer (``request.client.host``) is always the baseline. It is
      whatever the kernel reports as the connecting socket — unforgeable
      by the client itself.
    - ``X-Real-IP`` is **only** honored if the TCP peer is in the
      ``AUTH_TRUSTED_PROXIES`` allowlist (set via env var, comma-separated
      CIDR, single IPs or hostnames). When set, the gateway is assumed to be
      behind a reverse proxy (nginx, Cloudflare, ALB, …) that overwrites
      ``X-Real-IP`` with the original client address. The compose files
      name their bundled ``nginx`` service here by default.
    - With no ``AUTH_TRUSTED_PROXIES`` set, ``X-Real-IP`` is silently
      ignored — closing the bypass where any client could rotate the
      header to dodge per-IP rate limits in dev / direct-gateway mode.

    ``X-Forwarded-For`` is intentionally NOT used because it is naturally
    client-controlled at the *first* hop and the trust chain is harder to
    audit per-request. A request without ``X-Real-IP`` never resolves a
    hostname entry.
    """
    peer_host = request.client.host if request.client else None
    real_ip = request.headers.get("x-real-ip", "").strip()

    if peer_host and real_ip:
        try:
            peer_ip = ip_address(peer_host)
        except ValueError:
            # peer_host wasn't a parseable IP (e.g. "unknown") — fall through
            peer_ip = None
        if peer_ip is not None and await _is_trusted_proxy(peer_ip):
            return real_ip

    return peer_host or "unknown"


async def _check_rate_limit(ip: str) -> None:
    """Raise 429 if the IP is currently locked out.

    The policy is handed to the store as an async callable and resolved
    lazily, inside the store's single session: a clean IP (no failed attempts
    recorded — the overwhelming majority of logins) never pays the config
    read, and ``get_app_config`` re-hashes config.yaml on every call while
    this endpoint is unauthenticated. A recorded IP — including an
    already-locked attacker flooding the endpoint — resolves it exactly once,
    off the event loop via ``asyncio.to_thread`` (the stat + hash must not
    block the loop), and the SQL store serves the probe, the resolution and
    the decision from one connection-pool checkout instead of two.

    The policy read is a yield point: another request for the same IP may
    delete or replace the record meanwhile, so the store decides on a fresh
    read taken after it and guards its own mutations against that snapshot —
    a record replaced mid-flight (e.g. a successful login followed by a new
    failure) is never clobbered by a stale decision.
    """
    store = await _login_throttle_store()

    async def policy() -> tuple[int, float]:
        return await asyncio.to_thread(_login_throttle_policy)

    remaining = await store.check(ip, policy=policy, now=time.time())
    if remaining > 0.0:
        raise HTTPException(
            status_code=429,
            detail="Too many login attempts. Try again later.",
        )


async def _record_login_failure(ip: str) -> None:
    """Record a failed login attempt for the given IP.

    Policy resolution runs off the event loop (see ``_check_rate_limit``):
    this is the first config read for a previously clean IP, and the login
    endpoint is unauthenticated.
    """
    store = await _login_throttle_store()
    try:
        max_attempts, lockout_seconds = await asyncio.to_thread(_login_throttle_policy)
    except Exception:
        # A malformed config keeps failing loudly, but dropping the failure
        # here would leave the IP clean — and a clean IP skips the config
        # read in _check_rate_limit, so every subsequent wrong password would
        # reach authenticate() again: unlimited password verification for as
        # long as the file stays broken. Count under the model defaults so
        # the throttle fails closed (the next check reads the broken config
        # before authenticate), then re-raise.
        from deerflow.config.auth_config import LocalAuthConfig

        fallback = LocalAuthConfig()
        await store.record_failure(ip, max_attempts=fallback.max_login_attempts, lockout_seconds=fallback.lockout_seconds, now=time.time())
        raise
    await store.record_failure(ip, max_attempts=max_attempts, lockout_seconds=lockout_seconds, now=time.time())


async def _record_login_success(ip: str) -> None:
    """Clear the failure counter for the given IP on successful login."""
    store = await _login_throttle_store()
    await store.reset(ip)


# ── Endpoints ─────────────────────────────────────────────────────────────


@router.post("/login/local", response_model=LoginResponse)
async def login_local(
    request: Request,
    response: Response,
    form_data: OAuth2PasswordRequestForm = Depends(),
    remember_me: bool = Form(default=True),
):
    """Local email/password login."""
    client_ip = await _get_client_ip(request)
    await _check_rate_limit(client_ip)

    user = await get_local_provider().authenticate({"email": form_data.username, "password": form_data.password})

    if user is None:
        await _record_login_failure(client_ip)
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail=AuthErrorResponse(code=AuthErrorCode.INVALID_CREDENTIALS, message="Incorrect email or password").model_dump(),
        )

    await _record_login_success(client_ip)
    token = create_access_token(str(user.id), token_version=user.token_version)
    _set_session_cookie(response, token, request, remember_me=remember_me)

    return LoginResponse(
        expires_in=get_auth_config().token_expiry_days * 24 * 3600,
        needs_setup=user.needs_setup,
    )


def _local_registration_enabled() -> bool:
    """Whether visitors may self-register a local account.

    Local registration bypasses the OIDC provisioning policy entirely
    (allowed_email_domains, require_verified_email, auto_create_users are only
    enforced in the SSO callback), so SSO-provisioned deployments need a way to
    close this path.

    ``config.yaml`` is absent in bare-app contexts that never load it (tests build the
    gateway without one). Registration was unconditionally open before this gate existed,
    so an absent config file falls back to that same default rather than turning these two
    endpoints into a hard dependency on the file. Only ``FileNotFoundError`` is caught:
    a malformed config must not silently re-open a closed deployment, so it propagates.

    ``/register`` reads this fresh on every request (``get_app_config`` reloads on file
    change); ``/setup-status`` may serve it up to 60s stale via its per-IP result cache.
    Both are unauthenticated and ``get_app_config`` stats and re-hashes the config
    files on every call, so they run this through ``asyncio.to_thread``.
    """
    from deerflow.config.app_config import get_app_config

    try:
        return get_app_config().auth.local.allow_registration
    except FileNotFoundError:
        return True


@router.post("/register", response_model=UserResponse, status_code=status.HTTP_201_CREATED)
async def register(request: Request, response: Response, body: RegisterRequest):
    """Register a new user account (always 'user' role).

    The first admin is created explicitly through /initialize. This endpoint creates regular users.
    Auto-login by setting the session cookie.

    Returns 403 when ``auth.local.allow_registration`` is false.
    """
    if not await asyncio.to_thread(_local_registration_enabled):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail=AuthErrorResponse(code=AuthErrorCode.REGISTRATION_DISABLED, message="Self-registration is disabled on this deployment").model_dump(),
        )

    try:
        user = await get_local_provider().create_user(email=body.email, password=body.password, system_role="user")
    except ValueError:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=AuthErrorResponse(code=AuthErrorCode.EMAIL_ALREADY_EXISTS, message="Email already registered").model_dump(),
        )

    token = create_access_token(str(user.id), token_version=user.token_version)
    _set_session_cookie(response, token, request, remember_me=body.remember_me)

    return UserResponse(id=str(user.id), email=user.email, system_role=user.system_role, oauth_provider=user.oauth_provider)


@router.post("/logout", response_model=MessageResponse)
async def logout(request: Request, response: Response):
    """Logout current user by clearing the cookie."""
    is_https = is_secure_request(request)
    response.delete_cookie(key=ACCESS_TOKEN_COOKIE_NAME, secure=is_https, samesite="lax")
    response.delete_cookie(key=CSRF_COOKIE_NAME, secure=is_https, samesite="strict")
    response.delete_cookie(key=SESSION_PERSISTENCE_COOKIE_NAME, secure=is_https, samesite="lax")
    setattr(request.state, SKIP_AUTH_CSRF_COOKIE_STATE_ATTR, True)
    return MessageResponse(message="Successfully logged out")


@router.post("/change-password", response_model=MessageResponse)
async def change_password(request: Request, response: Response, body: ChangePasswordRequest):
    """Change password for the currently authenticated user.

    Also handles the first-boot setup flow:
    - If new_email is provided, updates email (checks uniqueness)
    - If user.needs_setup is True and new_email is given, clears needs_setup
    - Always increments token_version to invalidate old sessions
    - Re-issues session cookie with new token_version
    """
    from app.gateway.auth.password import hash_password_async, verify_password_async
    from app.gateway.auth_disabled import AUTH_SOURCE_AUTH_DISABLED, AUTH_SOURCE_PAT

    user = await get_current_user_from_request(request)

    if getattr(request.state, "auth_source", None) in {AUTH_SOURCE_PAT, AUTH_SOURCE_AUTH_DISABLED}:
        # PAT-authenticated callers must not alter auth state (#4849 point 6);
        # auth-disabled mode has no passwords to change.
        if getattr(request.state, "auth_source", None) == AUTH_SOURCE_PAT:
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="Password changes require interactive session authentication",
            )
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=AuthErrorResponse(
                code=AuthErrorCode.INVALID_CREDENTIALS,
                message="Password changes are not available when DEER_FLOW_AUTH_DISABLED=1.",
            ).model_dump(),
        )

    if user.password_hash is None:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=AuthErrorResponse(code=AuthErrorCode.INVALID_CREDENTIALS, message="OAuth users cannot change password").model_dump())

    if not await verify_password_async(body.current_password, user.password_hash):
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=AuthErrorResponse(code=AuthErrorCode.INVALID_CREDENTIALS, message="Current password is incorrect").model_dump())

    provider = get_local_provider()

    # Update email if provided
    if body.new_email is not None:
        existing = await provider.get_user_by_email(body.new_email)
        if existing and str(existing.id) != str(user.id):
            raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=AuthErrorResponse(code=AuthErrorCode.EMAIL_ALREADY_EXISTS, message="Email already in use").model_dump())
        user.email = body.new_email

    # Update password + bump version
    user.password_hash = await hash_password_async(body.new_password)
    user.token_version += 1

    # Clear setup flag if this is the setup flow
    if user.needs_setup and body.new_email is not None:
        user.needs_setup = False

    await provider.update_user(user)

    # Re-issue cookie with new token_version
    token = create_access_token(str(user.id), token_version=user.token_version)
    _set_session_cookie(response, token, request, remember_me=body.remember_me)
    _set_csrf_cookie(response, request)

    return MessageResponse(message="Password changed successfully")


@router.get("/me", response_model=UserResponse)
async def get_me(request: Request):
    """Get current authenticated user info, including effective permissions."""
    user = await get_current_user_from_request(request)
    auth = getattr(getattr(request, "state", None), "auth", None)
    if auth is not None:
        # AuthMiddleware already resolved the per-request permission set (with
        # PAT-scope intersection and internal-caller semantics applied) — reuse
        # it instead of evaluating the provider a second time.
        permissions: list[str] = list(auth.permissions)
    else:
        # Middleware-less composition: resolve exactly as _authenticate does.
        from app.gateway.authz import resolve_route_permissions_for_request

        permissions = await resolve_route_permissions_for_request(request, user)
    return UserResponse(
        id=str(user.id),
        email=user.email,
        system_role=user.system_role,
        needs_setup=user.needs_setup,
        oauth_provider=user.oauth_provider,
        permissions=permissions,
    )


# ── Personal Access Tokens (#4849) ────────────────────────────────────────


def require_session_source(request: Request) -> None:
    """Reject non-session credentials from auth-state-altering routes.

    PAT-authenticated callers must not manage PATs or change passwords
    (#4849 point 6): a leaked automation token could otherwise mint fresh
    long-lived credentials or lock out the human owner.
    """
    from app.gateway.auth_disabled import AUTH_SOURCE_SESSION

    if getattr(request.state, "auth_source", None) != AUTH_SOURCE_SESSION:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="This endpoint requires interactive session authentication")


class PATCreateRequest(BaseModel):
    name: str = Field(min_length=1, max_length=PAT_MAX_NAME_LENGTH)
    scopes: list[str] = Field(min_length=1)
    expires_in_days: int | None = Field(default=None, ge=1, le=365)  # None = never expires

    @field_validator("name")
    @classmethod
    def _strip_and_require_non_empty_name(cls, value: str) -> str:
        # A whitespace-only name passes min_length but would persist as an
        # empty label; the trimmed value is what gets stored and shown.
        stripped = value.strip()
        if not stripped:
            raise ValueError("PAT name must contain at least one non-whitespace character")
        return stripped


class PATCreatedResponse(BaseModel):
    """Create response — ``token`` is the raw show-once credential."""

    id: str
    name: str
    scopes: list[str]
    expires_at: str | None
    created_at: str
    token: str


class PATSummaryResponse(BaseModel):
    id: str
    name: str
    scopes: list[str]
    expires_at: str | None
    last_used_at: str | None
    created_at: str
    revoked_at: str | None


def _pat_summary(record: dict) -> PATSummaryResponse:
    return PATSummaryResponse(
        id=str(record["id"]),
        name=str(record["name"]),
        scopes=list(record.get("scopes") or []),
        expires_at=str(record["expires_at"]) if record.get("expires_at") else None,
        last_used_at=str(record["last_used_at"]) if record.get("last_used_at") else None,
        created_at=str(record["created_at"]),
        revoked_at=str(record["revoked_at"]) if record.get("revoked_at") else None,
    )


@router.post("/pats", status_code=status.HTTP_201_CREATED, response_model=PATCreatedResponse, dependencies=[Depends(require_session_source)])
async def create_pat(request: Request, body: PATCreateRequest):
    """Create a personal access token for the session user.

    The raw token is returned exactly once and cannot be retrieved again;
    only its SHA-256 digest is persisted.
    """
    from datetime import UTC, datetime, timedelta

    from app.gateway.auth.pat import generate_pat_token, pat_token_digest, validate_scopes
    from app.gateway.deps import get_pat_repo

    user = await get_current_user_from_request(request)
    try:
        scopes = validate_scopes(body.scopes)
    except ValueError as exc:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(exc)) from exc

    token = generate_pat_token()
    expires_at = datetime.now(UTC) + timedelta(days=body.expires_in_days) if body.expires_in_days is not None else None
    record = await get_pat_repo(request).create(
        user_id=str(user.id),
        name=body.name.strip(),
        scopes=scopes,
        token_digest=pat_token_digest(token),
        expires_at=expires_at,
    )
    return PATCreatedResponse(
        id=str(record["id"]),
        name=str(record["name"]),
        scopes=list(record.get("scopes") or []),
        expires_at=str(record["expires_at"]) if record.get("expires_at") else None,
        created_at=str(record["created_at"]),
        token=token,
    )


@router.get("/pats", response_model=list[PATSummaryResponse], dependencies=[Depends(require_session_source)])
async def list_pats(request: Request):
    """List the session user's tokens. Never returns digests or raw tokens."""
    from app.gateway.deps import get_pat_repo

    user = await get_current_user_from_request(request)
    records = await get_pat_repo(request).list_for_user(str(user.id))
    return [_pat_summary(record) for record in records]


@router.delete("/pats/{pat_id}", response_model=MessageResponse, dependencies=[Depends(require_session_source)])
async def revoke_pat(request: Request, pat_id: str):
    """Revoke one of the session user's tokens. Revocation is immediate."""
    from app.gateway.deps import get_pat_repo

    user = await get_current_user_from_request(request)
    revoked = await get_pat_repo(request).revoke(pat_id, str(user.id))
    if not revoked:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Token not found")
    return MessageResponse(message="Token revoked")


# Per-IP cache: ip → (timestamp, result_dict).
# Returns the cached result within the TTL instead of 429, because
# the answer (whether an admin exists) rarely changes and returning
# 429 breaks multi-tab / post-restart reconnection storms.
_SETUP_STATUS_CACHE: dict[str, tuple[float, dict]] = {}
_SETUP_STATUS_CACHE_TTL_SECONDS = 60
_MAX_TRACKED_SETUP_STATUS_IPS = 10000
_SETUP_STATUS_INFLIGHT: dict[str, asyncio.Task[dict]] = {}
_SETUP_STATUS_INFLIGHT_GUARD = asyncio.Lock()


@router.get("/setup-status")
async def setup_status(request: Request):
    """Check if an admin account exists. Returns needs_setup=True when no admin exists."""
    client_ip = await _get_client_ip(request)
    now = time.time()

    # Return cached result when within TTL — avoids 429 on multi-tab reconnection.
    cached = _SETUP_STATUS_CACHE.get(client_ip)
    if cached is not None:
        cached_time, cached_result = cached
        if now - cached_time < _SETUP_STATUS_CACHE_TTL_SECONDS:
            return cached_result

    async with _SETUP_STATUS_INFLIGHT_GUARD:
        # Recheck cache after waiting for the inflight guard.
        now = time.time()
        cached = _SETUP_STATUS_CACHE.get(client_ip)
        if cached is not None:
            cached_time, cached_result = cached
            if now - cached_time < _SETUP_STATUS_CACHE_TTL_SECONDS:
                return cached_result

        task = _SETUP_STATUS_INFLIGHT.get(client_ip)
        if task is None:
            # Evict stale entries when dict grows too large to bound memory usage.
            if len(_SETUP_STATUS_CACHE) >= _MAX_TRACKED_SETUP_STATUS_IPS:
                cutoff = now - _SETUP_STATUS_CACHE_TTL_SECONDS
                stale = [k for k, (t, _) in _SETUP_STATUS_CACHE.items() if t < cutoff]
                for k in stale:
                    del _SETUP_STATUS_CACHE[k]
                if len(_SETUP_STATUS_CACHE) >= _MAX_TRACKED_SETUP_STATUS_IPS:
                    by_time = sorted(_SETUP_STATUS_CACHE.items(), key=lambda entry: entry[1][0])
                    for k, _ in by_time[: len(by_time) // 2]:
                        del _SETUP_STATUS_CACHE[k]

            async def _compute_setup_status() -> dict:
                admin_count = await get_local_provider().count_admin_users()
                registration_enabled = await asyncio.to_thread(_local_registration_enabled)
                return {"needs_setup": admin_count == 0, "registration_enabled": registration_enabled}

            task = asyncio.create_task(_compute_setup_status())
            _SETUP_STATUS_INFLIGHT[client_ip] = task

    try:
        result = await task
    finally:
        async with _SETUP_STATUS_INFLIGHT_GUARD:
            if _SETUP_STATUS_INFLIGHT.get(client_ip) is task:
                del _SETUP_STATUS_INFLIGHT[client_ip]

    # Cache only the stable "initialized" result to avoid stale setup redirects.
    if result["needs_setup"] is False:
        _SETUP_STATUS_CACHE[client_ip] = (time.time(), result)
    else:
        _SETUP_STATUS_CACHE.pop(client_ip, None)
    return result


class InitializeAdminRequest(BaseModel):
    """Request model for first-boot admin account creation."""

    email: EmailStr
    password: str = Field(..., min_length=8)
    remember_me: bool = True

    _strong_password = field_validator("password")(classmethod(lambda cls, v: _validate_strong_password(v)))


@router.post("/initialize", response_model=UserResponse, status_code=status.HTTP_201_CREATED)
async def initialize_admin(request: Request, response: Response, body: InitializeAdminRequest):
    """Create the first admin account on initial system setup.

    Only callable when no admin exists. Returns 409 Conflict if an admin
    already exists, including when a concurrent first-boot request won the
    claim: the account is created through an atomic check-and-insert rather
    than a count followed by a create.

    On success, the admin account is created with ``needs_setup=False`` and
    the session cookie is set.
    """
    already_initialized = HTTPException(
        status_code=status.HTTP_409_CONFLICT,
        detail=AuthErrorResponse(code=AuthErrorCode.SYSTEM_ALREADY_INITIALIZED, message="System already initialized").model_dump(),
    )

    # Fast path only: an initialized system answers without hashing a
    # password. The claim below is what actually decides, because a count
    # read here cannot exclude a request already in flight.
    if await get_local_provider().count_admin_users() > 0:
        raise already_initialized

    try:
        user = await get_local_provider().create_first_admin(email=body.email, password=body.password)
    except ValueError:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=AuthErrorResponse(code=AuthErrorCode.EMAIL_ALREADY_EXISTS, message="Email already registered").model_dump(),
        )

    if user is None:
        raise already_initialized

    token = create_access_token(str(user.id), token_version=user.token_version)
    _set_session_cookie(response, token, request, remember_me=body.remember_me)

    return UserResponse(id=str(user.id), email=user.email, system_role=user.system_role, oauth_provider=user.oauth_provider)


# ── OIDC / SSO Endpoints ────────────────────────────────────────────────

_OIDC_PROVIDER_KEY_RE = re.compile(r"^[a-zA-Z0-9_-]+$")


def _get_oidc_service() -> OIDCService:
    """Get (or create) the singleton OIDC service instance."""
    if not hasattr(_get_oidc_service, "_instance"):
        _get_oidc_service._instance = OIDCService()  # type: ignore[attr-defined]
    return _get_oidc_service._instance  # type: ignore[attr-defined]


async def close_oidc_service() -> None:
    service = getattr(_get_oidc_service, "_instance", None)
    if service is not None:
        await service.close()
        delattr(_get_oidc_service, "_instance")


def _set_csrf_cookie(response: Response, request: Request) -> None:
    """Set the CSRF double-submit cookie (needed for GET-based OIDC callback)."""
    csrf_token = generate_csrf_token()
    secure, max_age = auth_csrf_cookie_settings(request)
    response.set_cookie(
        key=CSRF_COOKIE_NAME,
        value=csrf_token,
        httponly=False,  # Must be JS-readable for Double Submit Cookie pattern
        secure=secure,
        samesite="strict",
        # Persist for the same lifetime as the access_token (see _set_session_cookie)
        # so the double-submit pair is evicted together, never leaving a logged-in
        # session whose csrf_token was dropped (e.g. iOS Safari PWA termination).
        max_age=max_age,
    )


def _live_oidc_config() -> OIDCAuthConfig:
    from deerflow.config.app_config import get_app_config

    return get_app_config().auth.oidc


async def _oidc_config() -> OIDCAuthConfig:
    """The live ``auth.oidc`` config, read off the event loop.

    The SSO routes are unauthenticated, and ``get_app_config`` stats and
    re-hashes the config files on every call.
    """
    return await asyncio.to_thread(_live_oidc_config)


def _resolve_oidc_redirect_uri(request: Request, provider_id: str, provider_config: OIDCProviderConfig) -> str:
    """Resolve the redirect URI for an OIDC provider.

    Prefers the explicitly configured ``redirect_uri``. Falls back to
    constructing one from the request's own base URL for development.
    """
    if provider_config.redirect_uri:
        return provider_config.redirect_uri

    # Development fallback: build from the request's proxy-aware origin (honors
    # Forwarded / X-Forwarded-* the same way CSRF origin checks do) rather than
    # the raw Host header, so a spoofed Host cannot steer the IdP redirect_uri
    # and the scheme reflects the real client-facing protocol behind a proxy.
    origin = _request_origin(request)
    if not origin:
        origin = f"{request.url.scheme}://{request.headers.get('host', 'localhost:8001')}"
    return f"{origin}/api/v1/auth/callback/{provider_id}"


@router.get("/providers")
async def list_auth_providers():
    """List enabled SSO providers for the login page.

    Returns only safe frontend metadata — no secrets, endpoints, or
    internal configuration.
    """
    oidc_config = await _oidc_config()

    if not oidc_config.enabled:
        return {"providers": []}

    providers = []
    for provider_id, provider_cfg in oidc_config.providers.items():
        providers.append(
            {
                "id": provider_id,
                "display_name": provider_cfg.display_name,
                "type": "oidc",
            }
        )
    return {"providers": providers}


@router.get("/oauth/{provider}")
async def oauth_login(
    request: Request,
    provider: str,
    next: str | None = None,  # noqa: A002 (shadowing built-in is intentional — this is the query param name)
    remember_me: bool = True,
):
    """Initiate OIDC login flow.

    Redirects to the OIDC provider's authorization URL with state, nonce,
    and PKCE parameters. The ``next`` query parameter specifies where to
    redirect after successful login (default: /workspace).
    """
    oidc_config = await _oidc_config()

    if not oidc_config.enabled:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="SSO authentication is not enabled")

    if not _OIDC_PROVIDER_KEY_RE.match(provider):
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Invalid provider ID")

    provider_config = oidc_config.providers.get(provider)
    if not provider_config:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=f"Unknown SSO provider: {provider}")

    # Validate `next` / open redirect prevention
    redirect_path = validate_next_param(next) or "/workspace"

    # Resolve redirect URI
    redirect_uri = _resolve_oidc_redirect_uri(request, provider, provider_config)

    # Generate state, nonce, PKCE
    state_value = generate_oidc_state()
    nonce_value = generate_nonce() if provider_config.nonce_enabled else None
    code_verifier = generate_code_verifier() if provider_config.pkce_enabled else None
    code_challenge = compute_code_challenge(code_verifier) if code_verifier else None

    # Get provider metadata via discovery
    overrides = {
        "authorization_endpoint": provider_config.authorization_endpoint,
        "token_endpoint": provider_config.token_endpoint,
        "userinfo_endpoint": provider_config.userinfo_endpoint,
        "jwks_uri": provider_config.jwks_uri,
    }
    service = _get_oidc_service()
    try:
        metadata = await service.discover(provider_config.issuer, overrides)
    except OIDCError as exc:
        logger.error("OIDC discovery failed for provider %s: %s", provider, exc)
        raise HTTPException(status_code=status.HTTP_502_BAD_GATEWAY, detail="Failed to connect to SSO provider")

    auth_url = service.build_authorization_url(
        metadata=metadata,
        client_id=provider_config.client_id,
        redirect_uri=redirect_uri,
        scopes=provider_config.scopes,
        state=state_value,
        nonce=nonce_value,
        code_challenge=code_challenge,
    )

    # Set signed state cookie
    state_payload = OIDCStatePayload(
        provider=provider,
        state=state_value,
        nonce=nonce_value,
        code_verifier=code_verifier,
        next_path=redirect_path,
        remember_me=remember_me,
    )
    redirect_response = RedirectResponse(url=auth_url, status_code=status.HTTP_302_FOUND)
    set_state_cookie(redirect_response, request, state_payload)

    return redirect_response


@router.get("/callback/{provider}")
async def oauth_callback(
    request: Request,
    provider: str,
    code: str | None = None,
    state: str | None = None,
    error: str | None = None,
    error_description: str | None = None,
):
    """OIDC callback endpoint.

    Handles the OIDC provider's redirect after user authorization.
    Validates the state cookie, exchanges the code for tokens, validates
    the ID token, provisions/links the DeerFlow user, and sets the
    session cookie.
    """
    oidc_config = await _oidc_config()

    # ── Provider error ───────────────────────────────────────────────
    if error:
        logger.warning("OIDC provider returned error for %s: %s (description: %s)", provider, error, error_description)
        redirect = _build_error_redirect(oidc_config.frontend_base_url, "sso_failed")
        return RedirectResponse(url=redirect, status_code=status.HTTP_302_FOUND)

    if not oidc_config.enabled:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="SSO authentication is not enabled")

    if not _OIDC_PROVIDER_KEY_RE.match(provider):
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Invalid provider ID")

    provider_config = oidc_config.providers.get(provider)
    if not provider_config:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=f"Unknown SSO provider: {provider}")

    if not code or not state:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Missing code or state parameter")

    # ── Verify state cookie ──────────────────────────────────────────
    state_payload = get_state_cookie(request, provider)
    if not state_payload:
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Missing or expired OIDC state cookie")

    if not constant_time_equals(state_payload.state, state):
        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="OIDC state mismatch")

    # ── Resolve redirect URI ─────────────────────────────────────────
    redirect_uri = _resolve_oidc_redirect_uri(request, provider, provider_config)

    # ── Get metadata ─────────────────────────────────────────────────
    overrides = {
        "authorization_endpoint": provider_config.authorization_endpoint,
        "token_endpoint": provider_config.token_endpoint,
        "userinfo_endpoint": provider_config.userinfo_endpoint,
        "jwks_uri": provider_config.jwks_uri,
    }
    service = _get_oidc_service()
    try:
        metadata = await service.discover(provider_config.issuer, overrides)
    except OIDCError as exc:
        logger.error("OIDC discovery failed for provider %s during callback: %s", provider, exc)
        raise HTTPException(status_code=status.HTTP_502_BAD_GATEWAY, detail="Failed to connect to SSO provider")

    # ── Authenticate ─────────────────────────────────────────────────
    try:
        identity = await service.authenticate_callback(
            provider_id=provider,
            metadata=metadata,
            client_id=provider_config.client_id,
            client_secret=provider_config.client_secret,
            code=code,
            redirect_uri=redirect_uri,
            code_verifier=state_payload.code_verifier,
            nonce=state_payload.nonce,
            auth_method=provider_config.token_endpoint_auth_method,
        )
    except OIDCError as exc:
        logger.error("OIDC callback authentication failed for %s: %s", provider, exc)
        redirect = _build_error_redirect(oidc_config.frontend_base_url, "sso_failed")
        return RedirectResponse(url=redirect, status_code=status.HTTP_302_FOUND)

    # ── Provision / link user ────────────────────────────────────────
    try:
        result = await get_or_provision_oidc_user(provider, provider_config, identity, get_local_provider())
    except HTTPException as exc:
        error_map = {
            status.HTTP_403_FORBIDDEN: "sso_not_allowed",
            status.HTTP_409_CONFLICT: "sso_account_exists",
        }
        error_code = error_map.get(exc.status_code, "sso_failed")
        logger.warning("OIDC user provisioning failed for %s (%s): %s", identity.email, provider, exc.detail)
        redirect = _build_error_redirect(oidc_config.frontend_base_url, error_code)
        return RedirectResponse(url=redirect, status_code=status.HTTP_302_FOUND)

    user = result["user"]

    # ── Issue DeerFlow session ───────────────────────────────────────
    token = create_access_token(str(user.id), token_version=user.token_version)

    # Revalidate as defense-in-depth if future state writers populate this target.
    redirect_target = validate_next_param(state_payload.next_path) or "/workspace"
    frontend_base = oidc_config.frontend_base_url or ""
    callback_redirect = f"{frontend_base}/auth/callback?next={urllib.parse.quote(redirect_target)}"

    redirect_response = RedirectResponse(url=callback_redirect, status_code=status.HTTP_302_FOUND)

    # Set session cookie (reuse existing helper)
    _set_session_cookie(redirect_response, token, request, remember_me=state_payload.remember_me)

    # Set CSRF cookie (callback is a GET, so CSRF middleware won't set it)
    _set_csrf_cookie(redirect_response, request)

    # Delete state cookie
    delete_state_cookie(redirect_response, request, provider)

    return redirect_response


def _build_error_redirect(frontend_base_url: str | None, error_code: str) -> str:
    """Build a frontend redirect URL with an error parameter."""
    base = frontend_base_url or ""
    return f"{base}/login?error={error_code}"


def validate_next_param(next_param: str | None) -> str | None:
    """Validate and sanitize the ``next`` redirect parameter.

    Only allows relative paths starting with ``/``. Rejects protocol-relative
    URLs (``//``), absolute URLs, URLs with embedded protocols, backslashes
    that URL parsers may reinterpret as forward slashes, and control
    characters: browsers delete tab, LF and CR before parsing a URL, so
    ``/\\n//evil.example`` would otherwise reach the frontend as ``//evil.example``.
    """
    if not next_param:
        return None
    if not next_param.startswith("/"):
        return None
    if next_param.startswith("//") or next_param.startswith("http://") or next_param.startswith("https://"):
        return None
    if "\\" in next_param:
        return None
    if ":" in next_param:
        return None
    if any(ord(char) < 0x20 or ord(char) == 0x7F for char in next_param):
        return None
    return next_param