package clientapi_test

import (
	"bytes"
	"encoding/json"
	"io"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"path/filepath"
	"testing"

	"github.com/dariuszjaniak/warp/server/internal/clientapi"
	"github.com/dariuszjaniak/warp/server/internal/config"
	"github.com/dariuszjaniak/warp/server/internal/federation"
	"github.com/dariuszjaniak/warp/server/internal/httputil"
	"github.com/dariuszjaniak/warp/server/internal/matrix/signing"
	"github.com/dariuszjaniak/warp/server/internal/roomserver"
	"github.com/dariuszjaniak/warp/server/internal/settings"
	"github.com/dariuszjaniak/warp/server/internal/storage"
	_ "github.com/dariuszjaniak/warp/server/internal/storage/drivers"
	"github.com/dariuszjaniak/warp/server/internal/userapi"
)

const testServerName = "warp.example"

// testServer is a Client-Server API on a throwaway SQLite database.
//
// It is built from the real components rather than fakes: the point of these
// tests is the behaviour a client sees, and a fake userapi would only prove
// that the handlers call the methods the fake expects.
type testServer struct {
	t        *testing.T
	handler  http.Handler
	users    *userapi.API
	rooms    *roomserver.API
	settings *settings.Service
	fedGate  *federation.Gate
}

// newTestServer builds a server. tweak adjusts the options before the
// component is created, which is how a test turns on registration tokens or
// rate limiting.
func newTestServer(t *testing.T, tweak func(*clientapi.Options)) *testServer {
	t.Helper()

	path := filepath.ToSlash(filepath.Join(t.TempDir(), "warp.db"))
	db, err := storage.Open(t.Context(), storage.Config{
		Driver:           storage.DriverSQLite,
		ConnectionString: "file:" + path + "?_pragma=busy_timeout(5000)",
	}, slog.New(slog.DiscardHandler))
	if err != nil {
		t.Fatalf("open storage: %v", err)
	}
	t.Cleanup(func() { _ = db.Close() })
	if err := db.Migrate(t.Context()); err != nil {
		t.Fatalf("migrate: %v", err)
	}

	users, err := userapi.New(userapi.Options{
		ServerName: testServerName,
		Store:      db.Users(),
		Logger:     slog.New(slog.DiscardHandler),
	})
	if err != nil {
		t.Fatalf("userapi.New: %v", err)
	}

	// Registration is on and the limiter is off by default: almost every
	// test needs an account, and almost none is about rate limiting.
	settingsService, err := settings.New(t.Context(), db.Settings(), settings.Defaults{
		RegistrationEnabled:            true,
		RegistrationAllowRuntimeToggle: true,
		FederationAllowRuntimeToggle:   true,
	}, slog.New(slog.DiscardHandler))
	if err != nil {
		t.Fatalf("settings.New: %v", err)
	}
	gate := federation.NewGate(settingsService.FederationEnabled, nil)

	// A throwaway signing key: the roomserver signs every event it builds,
	// and the room endpoints are not registered without one.
	key, err := signing.Generate("test")
	if err != nil {
		t.Fatalf("signing.Generate: %v", err)
	}
	rooms, err := roomserver.New(roomserver.Options{
		ServerName:        testServerName,
		Store:             db.Rooms(),
		Profiles:          users,
		SigningKey:        key,
		FederationEnabled: settingsService.FederationEnabled,
		Logger:            slog.New(slog.DiscardHandler),
	})
	if err != nil {
		t.Fatalf("roomserver.New: %v", err)
	}

	opts := clientapi.Options{
		ServerName: testServerName,
		Users:      users,
		Rooms:      rooms,
		Settings:   settingsService,
		Federation: gate,
		Logger:     slog.New(slog.DiscardHandler),
	}
	if tweak != nil {
		tweak(&opts)
	}

	api, err := clientapi.New(opts)
	if err != nil {
		t.Fatalf("clientapi.New: %v", err)
	}
	router := httputil.NewRouter(nil)
	api.RegisterRoutes(router)

	return &testServer{
		t:        t,
		handler:  router,
		users:    users,
		rooms:    rooms,
		settings: settingsService,
		fedGate:  gate,
	}
}

// request is one HTTP call under test.
type request struct {
	method string
	path   string
	body   any
	token  string
	remote string
}

// do performs a request. A nil body sends none at all, which is what the
// endpoints whose body is optional have to cope with.
func (ts *testServer) do(req request) *httptest.ResponseRecorder {
	ts.t.Helper()

	var reader io.Reader
	if req.body != nil {
		raw, err := json.Marshal(req.body)
		if err != nil {
			ts.t.Fatalf("marshalling the request body: %v", err)
		}
		reader = bytes.NewReader(raw)
	}

	httpReq := httptest.NewRequest(req.method, req.path, reader)
	if req.body != nil {
		httpReq.Header.Set("Content-Type", "application/json")
	}
	if req.token != "" {
		httpReq.Header.Set("Authorization", "Bearer "+req.token)
	}
	if req.remote != "" {
		httpReq.RemoteAddr = req.remote
	}
	rec := httptest.NewRecorder()
	ts.handler.ServeHTTP(rec, httpReq)
	return rec
}

// get is the common read-only case.
func (ts *testServer) get(path, token string) *httptest.ResponseRecorder {
	ts.t.Helper()
	return ts.do(request{method: http.MethodGet, path: path, token: token})
}

// decode parses a response body as JSON.
func decode[T any](t *testing.T, rec *httptest.ResponseRecorder) T {
	t.Helper()
	var out T
	body := rec.Body.Bytes()
	if err := json.Unmarshal(body, &out); err != nil {
		t.Fatalf("response is not JSON (%s): %v", body, err)
	}
	return out
}

// jsonBody parses a response into a generic map.
func jsonBody(t *testing.T, rec *httptest.ResponseRecorder) map[string]any {
	t.Helper()
	return decode[map[string]any](t, rec)
}

// expectStatus fails unless the response has the given status.
func expectStatus(t *testing.T, rec *httptest.ResponseRecorder, want int) {
	t.Helper()
	if rec.Code != want {
		t.Fatalf("status = %d, want %d (body: %s)", rec.Code, want, rec.Body.String())
	}
}

// expectError fails unless the response is the given Matrix error.
func expectError(t *testing.T, rec *httptest.ResponseRecorder, status int, errcode string) {
	t.Helper()
	expectStatus(t, rec, status)
	body := jsonBody(t, rec)
	if got, _ := body["errcode"].(string); got != errcode {
		t.Errorf("errcode = %q, want %q (body: %s)", got, errcode, rec.Body.String())
	}
	if msg, _ := body["error"].(string); msg == "" {
		t.Error("the error envelope must carry a human-readable message")
	}
}

// account is a registered user plus its first session, which is what most
// tests need before they can do anything.
type account struct {
	UserID      string
	Localpart   string
	DeviceID    string
	AccessToken string
	Password    string
}

// register walks the full two-step registration flow, as a client does.
func (ts *testServer) register(localpart, password string) account {
	ts.t.Helper()

	rec := ts.do(request{
		method: http.MethodPost,
		path:   "/_matrix/client/v3/register",
		body:   map[string]any{"username": localpart, "password": password},
	})
	expectStatus(ts.t, rec, http.StatusUnauthorized)
	session, _ := jsonBody(ts.t, rec)["session"].(string)
	if session == "" {
		ts.t.Fatalf("the challenge carried no session: %s", rec.Body.String())
	}

	rec = ts.do(request{
		method: http.MethodPost,
		path:   "/_matrix/client/v3/register",
		body: map[string]any{
			"username": localpart,
			"password": password,
			"auth":     map[string]any{"type": "m.login.dummy", "session": session},
		},
	})
	expectStatus(ts.t, rec, http.StatusOK)

	body := jsonBody(ts.t, rec)
	acc := account{Password: password}
	acc.UserID, _ = body["user_id"].(string)
	acc.AccessToken, _ = body["access_token"].(string)
	acc.DeviceID, _ = body["device_id"].(string)
	acc.Localpart = userapi.NormaliseLocalpart(localpart)
	if acc.AccessToken == "" || acc.DeviceID == "" {
		ts.t.Fatalf("registration returned no session: %s", rec.Body.String())
	}
	return acc
}

// login creates a second session for an existing account.
func (ts *testServer) login(acc account, deviceID string) account {
	ts.t.Helper()

	body := map[string]any{
		"type":       "m.login.password",
		"identifier": map[string]any{"type": "m.id.user", "user": acc.UserID},
		"password":   acc.Password,
	}
	if deviceID != "" {
		body["device_id"] = deviceID
	}
	rec := ts.do(request{method: http.MethodPost, path: "/_matrix/client/v3/login", body: body})
	expectStatus(ts.t, rec, http.StatusOK)

	parsed := jsonBody(ts.t, rec)
	out := acc
	out.AccessToken, _ = parsed["access_token"].(string)
	out.DeviceID, _ = parsed["device_id"].(string)
	return out
}

// makeAdmin grants the admin flag to an existing account.
func (ts *testServer) makeAdmin(acc account) {
	ts.t.Helper()
	if err := ts.users.SetAdmin(ts.t.Context(), acc.Localpart, true); err != nil {
		ts.t.Fatalf("SetAdmin: %v", err)
	}
}

// withRateLimit is a tweak that turns on the limiter with a given policy.
func withRateLimit(limit config.RateLimit) func(*clientapi.Options) {
	return func(o *clientapi.Options) { o.RateLimit = limit }
}