package httpapi

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/http/httptest"
	"os"
	"strings"
	"testing"
	"time"

	"github.com/golang-migrate/migrate/v4"
	_ "github.com/golang-migrate/migrate/v4/database/postgres"
	"github.com/golang-migrate/migrate/v4/source/iofs"
	"github.com/google/uuid"
	"github.com/jackc/pgx/v5/pgxpool"

	"github.com/mitbringsl/backend/internal/config"
	"github.com/mitbringsl/backend/migrations"
)

// End-to-end tests over the real HTTP stack (router + middleware + auth +
// stores) against a throwaway Postgres. Skipped unless TEST_DATABASE_URL is
// set; see internal/store/liststore_test.go for the Docker recipe.

var testPool *pgxpool.Pool

func TestMain(m *testing.M) {
	dsn := os.Getenv("TEST_DATABASE_URL")
	if dsn == "" {
		fmt.Println("TEST_DATABASE_URL not set – skipping httpapi integration tests")
		os.Exit(0)
	}
	src, err := iofs.New(migrations.FS, ".")
	if err != nil {
		fmt.Fprintf(os.Stderr, "create source: %v\n", err)
		os.Exit(1)
	}
	mg, err := migrate.NewWithSourceInstance("iofs", src, dsn)
	if err != nil {
		fmt.Fprintf(os.Stderr, "create migrate instance: %v\n", err)
		os.Exit(1)
	}
	defer mg.Close()
	if err := mg.Up(); err != nil && !errors.Is(err, migrate.ErrNoChange) {
		fmt.Fprintf(os.Stderr, "migrate up: %v\n", err)
		os.Exit(1)
	}
	pool, err := pgxpool.New(context.Background(), dsn)
	if err != nil {
		fmt.Fprintf(os.Stderr, "connect: %v\n", err)
		os.Exit(1)
	}
	testPool = pool
	code := m.Run()
	pool.Close()
	os.Exit(code)
}

func newTestServer(t *testing.T) *httptest.Server {
	t.Helper()
	cfg := &config.Config{
		HTTPAddr:          ":0",
		AppEnv:            "development",
		SessionTokenBytes: 32,
		SessionTokenTTL:   time.Hour,
		SessionCookieName: "test_session",
	}
	ts := httptest.NewServer(NewAPI(cfg, testPool).Handler())
	t.Cleanup(ts.Close)
	return ts
}

// registerUser creates an account via the public API and returns its bearer token.
func registerUser(t *testing.T, ts *httptest.Server) string {
	t.Helper()
	body := fmt.Sprintf(`{"email":%q,"password":"test-password-1"}`,
		fmt.Sprintf("%s@test.example", uuid.NewString()))
	status, data := doRequest(t, ts, http.MethodPost, "/auth/register", "", body)
	if status != http.StatusCreated {
		t.Fatalf("register: status = %d, body = %s", status, data)
	}
	var out struct {
		Token string `json:"token"`
	}
	if err := json.Unmarshal(data, &out); err != nil || out.Token == "" {
		t.Fatalf("register: no token in response (%v): %s", err, data)
	}
	return out.Token
}

// doRequest performs a JSON request with an optional bearer token and returns
// the status code and response body.
func doRequest(t *testing.T, ts *httptest.Server, method, path, token, body string) (int, []byte) {
	t.Helper()
	var rd io.Reader
	if body != "" {
		rd = strings.NewReader(body)
	}
	req, err := http.NewRequest(method, ts.URL+path, rd)
	if err != nil {
		t.Fatalf("build request: %v", err)
	}
	if token != "" {
		req.Header.Set("Authorization", "Bearer "+token)
	}
	if body != "" {
		req.Header.Set("Content-Type", "application/json")
	}
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("%s %s: %v", method, path, err)
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	if err != nil {
		t.Fatalf("read response: %v", err)
	}
	return resp.StatusCode, data
}

// TestSharedLists_InviteJoinAndSyncAccess covers the full sharing flow:
// the owner creates a list and shares the invite code, another user joins,
// both can sync ops on the shared list, and a third user without membership
// is locked out of every endpoint.
func TestSharedLists_InviteJoinAndSyncAccess(t *testing.T) {
	ts := newTestServer(t)
	alice := registerUser(t, ts)
	bob := registerUser(t, ts)
	carol := registerUser(t, ts)

	// Alice creates a list; the response already carries the invite code.
	status, data := doRequest(t, ts, http.MethodPost, "/api/lists", alice, `{"name":"Wocheneinkauf"}`)
	if status != http.StatusCreated {
		t.Fatalf("create list: status = %d, body = %s", status, data)
	}
	var created struct {
		ID         string `json:"id"`
		InviteCode string `json:"invite_code"`
	}
	if err := json.Unmarshal(data, &created); err != nil {
		t.Fatalf("create list: decode: %v (%s)", err, data)
	}
	if created.ID == "" || created.InviteCode == "" {
		t.Fatalf("create list: missing id or invite_code: %s", data)
	}
	listPath := "/api/lists/" + created.ID

	// The invite endpoint returns the same code for the owner.
	status, data = doRequest(t, ts, http.MethodPost, listPath+"/invite", alice, `{}`)
	if status != http.StatusOK {
		t.Fatalf("invite: status = %d, body = %s", status, data)
	}
	var inv struct {
		InviteCode string `json:"invite_code"`
	}
	if err := json.Unmarshal(data, &inv); err != nil || inv.InviteCode != created.InviteCode {
		t.Fatalf("invite: unexpected code (%v): %s", err, data)
	}

	// Bob joins via the invite code, typed lowercase.
	status, _ = doRequest(t, ts, http.MethodPost, "/api/lists/join", bob,
		fmt.Sprintf(`{"invite_code":%q}`, strings.ToLower(created.InviteCode)))
	if status != http.StatusOK {
		t.Fatalf("join: status = %d", status)
	}

	// Bob now sees the list in his overview and can open the detail view.
	status, data = doRequest(t, ts, http.MethodGet, "/api/lists", bob, "")
	if status != http.StatusOK || !strings.Contains(string(data), created.ID) {
		t.Fatalf("bob GET /api/lists: status = %d, body = %s", status, data)
	}
	status, data = doRequest(t, ts, http.MethodGet, listPath, bob, "")
	if status != http.StatusOK {
		t.Fatalf("bob GET detail: status = %d, body = %s", status, data)
	}

	// Bob pushes an op; Alice pulls it – sync works across members.
	pushBody := fmt.Sprintf(
		`{"client_id":%q,"ops":[{"client_seq":1,"op_type":"item_add","target_id":%q,"hlc_ts":1000,"payload":{"name":"Milch"}}]}`,
		uuid.NewString(), uuid.NewString(),
	)
	status, data = doRequest(t, ts, http.MethodPost, listPath+"/ops", bob, pushBody)
	if status != http.StatusOK {
		t.Fatalf("bob push ops: status = %d, body = %s", status, data)
	}
	status, data = doRequest(t, ts, http.MethodGet, listPath+"/ops?since=0", alice, "")
	if status != http.StatusOK || !strings.Contains(string(data), "Milch") {
		t.Fatalf("alice pull ops: status = %d, body = %s", status, data)
	}

	// Carol (no membership) is locked out of detail, ops and invite.
	if status, _ = doRequest(t, ts, http.MethodGet, listPath, carol, ""); status != http.StatusNotFound {
		t.Errorf("carol GET detail: status = %d, want 404", status)
	}
	if status, _ = doRequest(t, ts, http.MethodPost, listPath+"/ops", carol, pushBody); status != http.StatusNotFound {
		t.Errorf("carol push ops: status = %d, want 404", status)
	}
	if status, _ = doRequest(t, ts, http.MethodGet, listPath+"/ops?since=0", carol, ""); status != http.StatusNotFound {
		t.Errorf("carol pull ops: status = %d, want 404", status)
	}
	if status, _ = doRequest(t, ts, http.MethodPost, listPath+"/invite", carol, `{}`); status != http.StatusNotFound {
		t.Errorf("carol invite: status = %d, want 404", status)
	}
	// Carol's own list overview must not leak the shared list.
	status, data = doRequest(t, ts, http.MethodGet, "/api/lists", carol, "")
	if status != http.StatusOK {
		t.Fatalf("carol GET /api/lists: status = %d, body = %s", status, data)
	}
	if strings.Contains(string(data), created.ID) {
		t.Error("carol must not see the shared list in GET /api/lists")
	}

	// Invalid invite code and idempotent re-join.
	if status, _ = doRequest(t, ts, http.MethodPost, "/api/lists/join", bob, `{"invite_code":"NOPE0000"}`); status != http.StatusBadRequest {
		t.Errorf("join with invalid code: status = %d, want 400", status)
	}
	if status, _ = doRequest(t, ts, http.MethodPost, "/api/lists/join", bob,
		fmt.Sprintf(`{"invite_code":%q}`, created.InviteCode)); status != http.StatusOK {
		t.Errorf("idempotent re-join: status = %d, want 200", status)
	}
}

func TestProtectedEndpointsRequireAuth(t *testing.T) {
	ts := newTestServer(t)
	listID := uuid.NewString()
	paths := []struct {
		method, path string
		body         string
	}{
		{http.MethodGet, "/api/lists", ""},
		{http.MethodPost, "/api/lists", `{"name":"x"}`},
		{http.MethodGet, "/api/lists/" + listID, ""},
		{http.MethodPost, "/api/lists/join", `{"invite_code":"ABCD1234"}`},
		{http.MethodPost, "/api/lists/" + listID + "/invite", `{}`},
		{http.MethodPost, "/api/lists/" + listID + "/ops", `{}`},
		{http.MethodGet, "/api/lists/" + listID + "/ops?since=0", ""},
		{http.MethodGet, "/api/suggestions?q=mi", ""},
	}
	for _, p := range paths {
		if status, _ := doRequest(t, ts, p.method, p.path, "", p.body); status != http.StatusUnauthorized {
			t.Errorf("%s %s without token: status = %d, want 401", p.method, p.path, status)
		}
	}
}