"""
Tests for backend/api/auth.py (Plan 02-02, Task 1).

Covers: register, login (TOTP, backup codes, password_must_change), refresh,
logout, me, change-password, per-account rate limiting, Origin validation,
and CSP headers.

Uses the async_client fixture from conftest.py.

Note on mock Redis: app.state.redis is set to a FakeRedis-like dict-based
mock so that per-account rate limiting can be exercised in isolation.
"""
from __future__ import annotations

import hashlib
import uuid
from datetime import datetime, timezone
from unittest.mock import AsyncMock, MagicMock, patch

import pytest
import pytest_asyncio
from httpx import ASGITransport, AsyncClient
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from db.models import BackupCode, Quota, User


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

async def _register(async_client, handle="testuser", email="t@example.com", password="ValidPass12!"):
    """Register a user and return the response."""
    return await async_client.post(
        "/api/auth/register",
        json={"handle": handle, "email": email, "password": password},
    )


async def _login(async_client, email="t@example.com", password="ValidPass12!", **extra):
    body = {"email": email, "password": password}
    body.update(extra)
    return await async_client.post("/api/auth/login", json=body)


# ── Fake Redis for per-account rate limiting ──────────────────────────────────

class FakeRedis:
    """In-memory fake Redis for testing rate limits and TOTP replay prevention."""

    def __init__(self):
        self._store: dict = {}

    async def get(self, key):
        entry = self._store.get(key)
        if entry is None:
            return None
        val, exp = entry
        if exp is not None and datetime.now(timezone.utc).timestamp() > exp:
            del self._store[key]
            return None
        return val

    async def incr(self, key):
        entry = self._store.get(key)
        if entry is None:
            self._store[key] = (1, None)
            return 1
        val, exp = entry
        new_val = val + 1
        self._store[key] = (new_val, exp)
        return new_val

    async def expire(self, key, seconds):
        if key in self._store:
            val, _ = self._store[key]
            deadline = datetime.now(timezone.utc).timestamp() + seconds
            self._store[key] = (val, deadline)

    async def set(self, key, value, ex=None):
        deadline = None
        if ex is not None:
            deadline = datetime.now(timezone.utc).timestamp() + ex
        self._store[key] = (value, deadline)

    async def close(self):
        pass


@pytest_asyncio.fixture
async def authed_client(db_session: AsyncSession):
    """Async HTTP test client with DB override AND fake Redis on app.state.redis.

    Each test gets a fresh FakeRedis instance (reset state). The slowapi
    in-memory rate limiter is also reset between tests so that IP-level
    counts from one test don't bleed into the next.
    """
    from deps.db import get_db
    from main import app
    from api.auth import limiter as auth_limiter

    app.dependency_overrides[get_db] = lambda: db_session
    fake_redis = FakeRedis()
    app.state.redis = fake_redis

    # Reset slowapi's in-memory storage so previous test IP counters don't
    # interfere with the current test's rate limit assertions.
    try:
        auth_limiter._storage.reset()
    except Exception:
        try:
            # Fallback: clear internal storage dict directly
            storage_obj = auth_limiter._storage
            if hasattr(storage_obj, "_storage"):
                storage_obj._storage.clear()
        except Exception:
            pass

    async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as c:
        yield c

    app.dependency_overrides.clear()
    # Reset redis to avoid leaking state between test files
    app.state.redis = None


# ── Tests — register ──────────────────────────────────────────────────────────

@pytest.mark.asyncio
async def test_register_success(authed_client):
    """POST /api/auth/register with valid data returns 201 with id and handle."""
    resp = await _register(authed_client)
    assert resp.status_code == 201, resp.text
    data = resp.json()
    assert "id" in data
    assert data["handle"] == "testuser"
    assert data["email"] == "t@example.com"


@pytest.mark.asyncio
async def test_register_weak_password(authed_client):
    """POST /api/auth/register with a short password returns 422."""
    resp = await authed_client.post(
        "/api/auth/register",
        json={"handle": "u", "email": "u@example.com", "password": "short"},
    )
    assert resp.status_code == 422


@pytest.mark.asyncio
async def test_register_duplicate_email(authed_client):
    """Registering the same email twice returns 409."""
    await _register(authed_client, handle="u1", email="dup@example.com")
    resp = await _register(authed_client, handle="u2", email="dup@example.com")
    assert resp.status_code == 409
    assert "already in use" in resp.json()["detail"].lower()


# ── Tests — login ─────────────────────────────────────────────────────────────

@pytest.mark.asyncio
async def test_login_wrong_password(authed_client):
    """POST /api/auth/login with wrong password returns 401."""
    await _register(authed_client)
    resp = await _login(authed_client, password="WrongPass99!")
    assert resp.status_code == 401
    assert "Incorrect email or password" in resp.json()["detail"]


@pytest.mark.asyncio
async def test_login_success(authed_client):
    """Register then login returns 200 with access_token; Set-Cookie has HttpOnly + SameSite."""
    await _register(authed_client)
    resp = await _login(authed_client)
    assert resp.status_code == 200, resp.text
    data = resp.json()
    assert "access_token" in data
    cookie_header = resp.headers.get("set-cookie", "")
    assert "HttpOnly" in cookie_header or "httponly" in cookie_header.lower()
    assert "SameSite=Strict" in cookie_header or "samesite=strict" in cookie_header.lower()


@pytest.mark.asyncio
async def test_me_requires_auth(authed_client):
    """GET /api/auth/me without Bearer token returns 403 (HTTPBearer default)."""
    resp = await authed_client.get("/api/auth/me")
    # HTTPBearer raises 403 when no Authorization header present
    assert resp.status_code in (401, 403)


@pytest.mark.asyncio
async def test_login_password_must_change(authed_client, db_session: AsyncSession):
    """Login for user with password_must_change=True returns 200 with requires_password_change=True, no Set-Cookie."""
    await _register(authed_client, handle="pmcu", email="pmc@example.com")
    # Flip the flag in the DB
    result = await db_session.execute(select(User).where(User.email == "pmc@example.com"))
    user = result.scalar_one()
    user.password_must_change = True
    await db_session.commit()

    resp = await _login(authed_client, email="pmc@example.com")
    assert resp.status_code == 200
    data = resp.json()
    assert data.get("requires_password_change") is True
    assert "access_token" not in data
    # No Set-Cookie header
    assert "set-cookie" not in resp.headers


@pytest.mark.asyncio
async def test_change_password_breach(authed_client):
    """POST /api/auth/change-password with breached new password returns 422."""
    await _register(authed_client, handle="cpb", email="cpb@example.com")
    login_resp = await _login(authed_client, email="cpb@example.com")
    token = login_resp.json()["access_token"]

    with patch("services.auth.check_hibp", return_value=True) as mock_hibp:
        resp = await authed_client.post(
            "/api/auth/change-password",
            json={"current_password": "ValidPass12!", "new_password": "StrongNew99!@"},
            headers={"Authorization": f"Bearer {token}"},
        )

    assert resp.status_code == 422
    assert "breach" in resp.json()["detail"].lower()


@pytest.mark.asyncio
async def test_change_password_wrong_current(authed_client):
    """POST /api/auth/change-password with wrong current_password returns 401."""
    await _register(authed_client, handle="cpw", email="cpw@example.com")
    login_resp = await _login(authed_client, email="cpw@example.com")
    token = login_resp.json()["access_token"]

    resp = await authed_client.post(
        "/api/auth/change-password",
        json={"current_password": "WrongCurrent9!", "new_password": "NewStrong99!@"},
        headers={"Authorization": f"Bearer {token}"},
    )
    assert resp.status_code == 401


@pytest.mark.asyncio
async def test_change_password_success(authed_client):
    """POST /api/auth/change-password with correct current + strong new password returns 200."""
    await _register(authed_client, handle="cps", email="cps@example.com")
    login_resp = await _login(authed_client, email="cps@example.com")
    token = login_resp.json()["access_token"]

    with patch("services.auth.check_hibp", return_value=False):
        resp = await authed_client.post(
            "/api/auth/change-password",
            json={"current_password": "ValidPass12!", "new_password": "NewStrong99!@"},
            headers={"Authorization": f"Bearer {token}"},
        )
    assert resp.status_code == 200
    assert resp.json()["message"] == "Password updated"


# ── Tests — Origin validation middleware ──────────────────────────────────────

@pytest.mark.asyncio
async def test_origin_rejected(authed_client):
    """POST /api/auth/login with a cross-origin Origin header returns 403."""
    resp = await authed_client.post(
        "/api/auth/login",
        json={"email": "x@x.com", "password": "any"},
        headers={"Origin": "https://evil.example"},
    )
    assert resp.status_code == 403


@pytest.mark.asyncio
async def test_origin_allowed(authed_client):
    """POST /api/auth/login with an allowed Origin proceeds to auth (not 403)."""
    resp = await authed_client.post(
        "/api/auth/login",
        json={"email": "nobody@example.com", "password": "any"},
        headers={"Origin": "http://localhost:5173"},
    )
    # Not 403 — may be 401 (wrong credentials) or 200
    assert resp.status_code != 403


# ── Tests — per-account rate limiting ────────────────────────────────────────

@pytest.mark.asyncio
async def test_per_account_rate_limit(authed_client):
    """11 consecutive login attempts with the same email returns 429 on the 11th."""
    email = "ratelimit@example.com"
    for i in range(10):
        resp = await authed_client.post(
            "/api/auth/login",
            json={"email": email, "password": "WrongPass99!"},
        )
        assert resp.status_code in (401, 200), f"Unexpected {resp.status_code} on attempt {i+1}"

    # 11th attempt should be rate limited
    resp = await authed_client.post(
        "/api/auth/login",
        json={"email": email, "password": "WrongPass99!"},
    )
    assert resp.status_code == 429, f"Expected 429 on 11th attempt, got {resp.status_code}: {resp.text}"


# ── Tests — backup codes ──────────────────────────────────────────────────────

@pytest.mark.asyncio
async def test_login_backup_code_success(authed_client, db_session: AsyncSession):
    """Login with a valid backup code returns 200 + access_token and invalidates the code."""
    await _register(authed_client, handle="bcu", email="bcu@example.com")

    result = await db_session.execute(select(User).where(User.email == "bcu@example.com"))
    user = result.scalar_one()

    # Enable TOTP on the user (so the backup code path is exercised)
    user.totp_enabled = True
    user.totp_secret = "JBSWY3DPEHPK3PXP"  # dummy secret

    # Store a backup code
    plaintext_code = "ABCD1234"
    from services.auth import hash_password
    backup_code_row = BackupCode(
        id=uuid.uuid4(),
        user_id=user.id,
        code_hash=hash_password(plaintext_code),
        used_at=None,
    )
    db_session.add(backup_code_row)
    await db_session.commit()

    resp = await _login(authed_client, email="bcu@example.com", backup_code=plaintext_code)
    assert resp.status_code == 200, resp.text
    data = resp.json()
    assert "access_token" in data

    # Verify the code was marked used
    await db_session.refresh(backup_code_row)
    assert backup_code_row.used_at is not None


@pytest.mark.asyncio
async def test_login_backup_code_reuse(authed_client, db_session: AsyncSession):
    """Using the same backup code a second time returns 401."""
    await _register(authed_client, handle="bcr", email="bcr@example.com")

    result = await db_session.execute(select(User).where(User.email == "bcr@example.com"))
    user = result.scalar_one()
    user.totp_enabled = True
    user.totp_secret = "JBSWY3DPEHPK3PXP"

    plaintext_code = "EFGH5678"
    from services.auth import hash_password
    backup_code_row = BackupCode(
        id=uuid.uuid4(),
        user_id=user.id,
        code_hash=hash_password(plaintext_code),
        used_at=None,
    )
    db_session.add(backup_code_row)
    await db_session.commit()

    # First use: should succeed
    resp1 = await _login(authed_client, email="bcr@example.com", backup_code=plaintext_code)
    assert resp1.status_code == 200, resp1.text

    # Second use: should fail
    resp2 = await _login(authed_client, email="bcr@example.com", backup_code=plaintext_code)
    assert resp2.status_code == 401
    assert "Invalid or already used code" in resp2.json()["detail"]


@pytest.mark.asyncio
async def test_login_backup_code_invalid(authed_client, db_session: AsyncSession):
    """POST /api/auth/login with an unknown backup code returns 401."""
    await _register(authed_client, handle="bci", email="bci@example.com")

    result = await db_session.execute(select(User).where(User.email == "bci@example.com"))
    user = result.scalar_one()
    user.totp_enabled = True
    user.totp_secret = "JBSWY3DPEHPK3PXP"
    await db_session.commit()

    resp = await _login(authed_client, email="bci@example.com", backup_code="XXXXXXXX")
    assert resp.status_code == 401
    assert "Invalid or already used code" in resp.json()["detail"]


@pytest.mark.asyncio
async def test_login_totp_takes_precedence(authed_client, db_session: AsyncSession):
    """When both totp_code and backup_code are provided, the TOTP path is used (not backup)."""
    await _register(authed_client, handle="ttp", email="ttp@example.com")

    result = await db_session.execute(select(User).where(User.email == "ttp@example.com"))
    user = result.scalar_one()
    user.totp_enabled = True
    user.totp_secret = "JBSWY3DPEHPK3PXP"

    # Store a valid backup code
    plaintext_code = "TOTP1234"
    from services.auth import hash_password
    backup_code_row = BackupCode(
        id=uuid.uuid4(),
        user_id=user.id,
        code_hash=hash_password(plaintext_code),
        used_at=None,
    )
    db_session.add(backup_code_row)
    await db_session.commit()

    # Use both fields — totp_code is wrong, backup_code is valid
    # If TOTP takes precedence, the wrong totp_code should cause 401
    with patch("services.auth.verify_totp", return_value=False) as mock_totp:
        resp = await _login(
            authed_client,
            email="ttp@example.com",
            totp_code="000000",
            backup_code=plaintext_code,
        )
        # verify_totp was called (TOTP path taken)
        mock_totp.assert_called_once()

    # The backup code path was NOT taken — code remains unused
    await db_session.refresh(backup_code_row)
    assert backup_code_row.used_at is None, "Backup code should NOT have been consumed when totp_code is provided"
    assert resp.status_code == 401