"""Integration tests for the admin usage dashboard routes (U7).

Uses FastAPI TestClient with a test app that mounts only the
``admin_router`` from ``routes.admin``. The ``_require_admin``
dependency is overridden via ``app.dependency_overrides`` so the tests
don't need real JWTs — they can simulate admin and non-admin callers
directly.

The LLM gateway is replaced with a stub that exposes a
``_usage_tracker.store`` attribute pointing at an
:class:`InMemoryUsageStore` pre-populated with test records.
"""

from __future__ import annotations

import csv
import io
import json
from pathlib import Path
from typing import Any

import pytest
from fastapi import FastAPI, HTTPException
from fastapi.testclient import TestClient

from agentkit.llm.protocol import TokenUsage
from agentkit.llm.providers.usage_store import InMemoryUsageStore
from agentkit.server.admin.usage_service import set_usage_service
from agentkit.server.auth.models import init_auth_db
from agentkit.server.routes import admin as admin_routes_module


# ---------------------------------------------------------------------------
# Fixtures
# ---------------------------------------------------------------------------


class _StubTracker:
    """Minimal stub matching the UsageTracker surface used by routes."""

    def __init__(self, store: InMemoryUsageStore) -> None:
        self.store = store


class _StubGateway:
    """Minimal stub matching the LLMGateway surface used by routes."""

    def __init__(self, store: InMemoryUsageStore) -> None:
        self._usage_tracker = _StubTracker(store)


@pytest.fixture
def store() -> InMemoryUsageStore:
    return InMemoryUsageStore()


@pytest.fixture
def populated_store() -> InMemoryUsageStore:
    """Pre-populated store with a mix of records across users/depts/models."""
    s = InMemoryUsageStore()
    s.record(
        "agent1",
        "gpt-4o",
        TokenUsage(prompt_tokens=60, completion_tokens=40),
        cost=0.05,
        latency_ms=200,
        user_id="u1",
        department_id="d1",
    )
    s.record(
        "agent1",
        "claude",
        TokenUsage(prompt_tokens=120, completion_tokens=80),
        cost=0.10,
        latency_ms=300,
        user_id="u1",
        department_id="d1",
    )
    s.record(
        "agent2",
        "gpt-4o",
        TokenUsage(prompt_tokens=30, completion_tokens=20),
        cost=0.02,
        latency_ms=100,
        user_id="u2",
        department_id="d2",
    )
    s.record(
        "agent3",
        "gpt-4o",
        TokenUsage(prompt_tokens=300, completion_tokens=200),
        cost=0.50,
        latency_ms=400,
        user_id="u3",
        department_id="d1",
    )
    return s


@pytest.fixture(autouse=True)
def _reset_singletons():
    set_usage_service(None)
    yield
    set_usage_service(None)


@pytest.fixture
async def tmp_auth_db(tmp_path: Path) -> Path:
    db_path = tmp_path / "usage_routes.db"
    await init_auth_db(db_path)
    return db_path


def _make_admin_app(store: InMemoryUsageStore, tmp_auth_db: Path) -> FastAPI:
    """Build a FastAPI app with admin router + stub gateway."""
    app = FastAPI()
    app.state.auth_db_path = str(tmp_auth_db)
    app.state.llm_gateway = _StubGateway(store)
    app.include_router(admin_routes_module.admin_router, prefix="/api/v1")
    # Default: allow admin access.
    app.dependency_overrides[admin_routes_module._require_admin] = lambda: _make_admin_user()
    return app


def _make_admin_user() -> dict[str, Any]:
    return {"user_id": "admin-1", "username": "admin", "role": "admin"}


def _raise_forbidden() -> dict[str, Any]:
    raise HTTPException(status_code=403, detail="Admin permission required")


# ---------------------------------------------------------------------------
# /admin/usage/summary
# ---------------------------------------------------------------------------


class TestUsageSummaryRoute:
    def test_returns_200_with_data(self, populated_store: InMemoryUsageStore, tmp_auth_db: Path):
        app = _make_admin_app(populated_store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/summary")
        assert resp.status_code == 200
        body = resp.json()
        assert body["total_tokens"] == 850
        assert abs(body["total_cost"] - 0.67) < 1e-6
        assert body["total_requests"] == 4
        assert "gpt-4o" in body["by_model"]
        assert "u1" in body["by_user"]
        assert "d1" in body["by_department"]

    def test_with_department_filter(self, populated_store: InMemoryUsageStore, tmp_auth_db: Path):
        app = _make_admin_app(populated_store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/summary", params={"department_id": "d2"})
        assert resp.status_code == 200
        body = resp.json()
        assert body["total_tokens"] == 50
        assert body["total_requests"] == 1

    def test_empty_store_returns_200_with_zeros(self, store: InMemoryUsageStore, tmp_auth_db: Path):
        app = _make_admin_app(store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/summary")
        assert resp.status_code == 200
        body = resp.json()
        assert body["total_tokens"] == 0
        assert body["total_cost"] == 0.0
        assert body["total_requests"] == 0

    def test_non_admin_returns_403(self, populated_store: InMemoryUsageStore, tmp_auth_db: Path):
        app = _make_admin_app(populated_store, tmp_auth_db)
        app.dependency_overrides[admin_routes_module._require_admin] = _raise_forbidden
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/summary")
        assert resp.status_code == 403


# ---------------------------------------------------------------------------
# /admin/usage/timeseries
# ---------------------------------------------------------------------------


class TestUsageTimeseriesRoute:
    def test_returns_200_with_data(self, populated_store: InMemoryUsageStore, tmp_auth_db: Path):
        app = _make_admin_app(populated_store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/timeseries")
        assert resp.status_code == 200
        body = resp.json()
        assert isinstance(body, list)
        assert len(body) >= 1
        assert "timestamp" in body[0]
        assert "tokens" in body[0]
        assert body[0]["tokens"] == 850

    def test_invalid_interval_returns_400(
        self, populated_store: InMemoryUsageStore, tmp_auth_db: Path
    ):
        app = _make_admin_app(populated_store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/timeseries", params={"interval": "week"})
        assert resp.status_code == 400

    def test_empty_store_returns_200_empty_list(self, store: InMemoryUsageStore, tmp_auth_db: Path):
        app = _make_admin_app(store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/timeseries")
        assert resp.status_code == 200
        assert resp.json() == []


# ---------------------------------------------------------------------------
# /admin/usage/by-model
# ---------------------------------------------------------------------------


class TestUsageByModelRoute:
    def test_returns_200_with_breakdown(
        self, populated_store: InMemoryUsageStore, tmp_auth_db: Path
    ):
        app = _make_admin_app(populated_store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/by-model")
        assert resp.status_code == 200
        body = resp.json()
        assert isinstance(body, list)
        models = {row["model"] for row in body}
        assert models == {"gpt-4o", "claude"}

    def test_empty_store_returns_200_empty_list(self, store: InMemoryUsageStore, tmp_auth_db: Path):
        app = _make_admin_app(store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/by-model")
        assert resp.status_code == 200
        assert resp.json() == []


# ---------------------------------------------------------------------------
# /admin/usage/top-users
# ---------------------------------------------------------------------------


class TestTopUsersRoute:
    def test_returns_200_sorted_by_tokens(
        self, populated_store: InMemoryUsageStore, tmp_auth_db: Path
    ):
        app = _make_admin_app(populated_store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/top-users")
        assert resp.status_code == 200
        body = resp.json()
        assert len(body) == 3
        # u3 (500), u1 (300), u2 (50)
        assert body[0]["user_id"] == "u3"
        assert body[0]["tokens"] == 500
        assert body[1]["user_id"] == "u1"
        assert body[2]["user_id"] == "u2"

    def test_limit_param_respected(self, populated_store: InMemoryUsageStore, tmp_auth_db: Path):
        app = _make_admin_app(populated_store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/top-users", params={"limit": 2})
        assert resp.status_code == 200
        body = resp.json()
        assert len(body) == 2

    def test_empty_store_returns_200_empty_list(self, store: InMemoryUsageStore, tmp_auth_db: Path):
        app = _make_admin_app(store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/top-users")
        assert resp.status_code == 200
        assert resp.json() == []


# ---------------------------------------------------------------------------
# /admin/usage/export
# ---------------------------------------------------------------------------


class TestUsageExportRoute:
    def test_csv_export_returns_200(self, populated_store: InMemoryUsageStore, tmp_auth_db: Path):
        app = _make_admin_app(populated_store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/export", params={"format": "csv"})
        assert resp.status_code == 200
        assert resp.headers["content-type"].startswith("text/csv")
        reader = csv.DictReader(io.StringIO(resp.text))
        rows = list(reader)
        assert len(rows) == 4
        assert "timestamp" in rows[0]
        assert "user_id" in rows[0]
        assert "department_id" in rows[0]

    def test_json_export_returns_200(self, populated_store: InMemoryUsageStore, tmp_auth_db: Path):
        app = _make_admin_app(populated_store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/export", params={"format": "json"})
        assert resp.status_code == 200
        # PlainTextResponse returns text/plain or application/json depending on media_type.
        body = json.loads(resp.text)
        assert isinstance(body, list)
        assert len(body) == 4

    def test_invalid_format_returns_400(
        self, populated_store: InMemoryUsageStore, tmp_auth_db: Path
    ):
        app = _make_admin_app(populated_store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/export", params={"format": "xml"})
        assert resp.status_code == 400

    def test_empty_store_csv_returns_header_only(
        self, store: InMemoryUsageStore, tmp_auth_db: Path
    ):
        app = _make_admin_app(store, tmp_auth_db)
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/export", params={"format": "csv"})
        assert resp.status_code == 200
        reader = csv.DictReader(io.StringIO(resp.text))
        rows = list(reader)
        assert rows == []
        # Header should still be present.
        assert "timestamp" in resp.text


# ---------------------------------------------------------------------------
# Missing gateway
# ---------------------------------------------------------------------------


class TestMissingGateway:
    def test_summary_returns_500_without_gateway(self, tmp_auth_db: Path):
        app = FastAPI()
        app.state.auth_db_path = str(tmp_auth_db)
        # No llm_gateway on app.state.
        app.include_router(admin_routes_module.admin_router, prefix="/api/v1")
        app.dependency_overrides[admin_routes_module._require_admin] = lambda: _make_admin_user()
        client = TestClient(app)
        resp = client.get("/api/v1/admin/usage/summary")
        assert resp.status_code == 500