package transport

import (
	"context"
	"encoding/json"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"wikijs-mcp/internal/server"
	"wikijs-mcp/internal/wikijs"

	"github.com/modelcontextprotocol/go-sdk/mcp"
)

func testLogger() *slog.Logger {
	return slog.New(slog.DiscardHandler)
}

func newTestServer(t *testing.T, wikiClient *wikijs.Client) *mcp.Server {
	t.Helper()
	return server.New(wikiClient, server.Options{Version: "test", Logger: testLogger()})
}

func newTestHandler(t *testing.T, authToken string) http.Handler {
	t.Helper()

	fakeWiki := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		_, _ = w.Write([]byte(`{"data":{"pages":{"single":{"id":1,"path":"/start","title":"Start","description":"","tags":[],"content":"body","createdAt":"","updatedAt":"","locale":"en"}}}}`))
	}))
	t.Cleanup(fakeWiki.Close)

	wikiClient, err := wikijs.New(fakeWiki.URL, "key")
	if err != nil {
		t.Fatalf("wikijs.New() error = %v", err)
	}
	srv := newTestServer(t, wikiClient)

	return NewHTTPHandler(HTTPOptions{
		Path:      "/mcp",
		AuthToken: authToken,
		Logger:    testLogger(),
		NewServer: func(*http.Request) *mcp.Server { return srv },
	})
}

func TestHealthzIsOpen(t *testing.T) {
	ts := httptest.NewServer(newTestHandler(t, "secret"))
	t.Cleanup(ts.Close)

	resp, err := http.Get(ts.URL + "/healthz")
	if err != nil {
		t.Fatalf("GET /healthz: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		t.Errorf("status = %d, want 200", resp.StatusCode)
	}
	var body map[string]string
	if err := json.NewDecoder(resp.Body).Decode(&body); err != nil {
		t.Fatalf("decode body: %v", err)
	}
	if body["status"] != "ok" {
		t.Errorf("body = %v", body)
	}
}

func TestMCPRequiresBearerToken(t *testing.T) {
	ts := httptest.NewServer(newTestHandler(t, "secret"))
	t.Cleanup(ts.Close)

	tests := []struct {
		name   string
		header string
		want   int
	}{
		{name: "missing", want: http.StatusUnauthorized},
		{name: "wrong token", header: "Bearer nope", want: http.StatusUnauthorized},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			req, _ := http.NewRequest(http.MethodPost, ts.URL+"/mcp", strings.NewReader(`{}`))
			req.Header.Set("Content-Type", "application/json")
			if tt.header != "" {
				req.Header.Set("Authorization", tt.header)
			}
			resp, err := http.DefaultClient.Do(req)
			if err != nil {
				t.Fatalf("POST /mcp: %v", err)
			}
			defer resp.Body.Close()

			if resp.StatusCode != tt.want {
				t.Errorf("status = %d, want %d", resp.StatusCode, tt.want)
			}
			if got := resp.Header.Get("WWW-Authenticate"); !strings.Contains(got, "Bearer") {
				t.Errorf("WWW-Authenticate = %q", got)
			}
		})
	}
}

func TestBearerSchemeIsCaseInsensitive(t *testing.T) {
	ts := httptest.NewServer(newTestHandler(t, "secret"))
	t.Cleanup(ts.Close)

	req, _ := http.NewRequest(http.MethodPost, ts.URL+"/mcp", strings.NewReader(`{}`))
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Authorization", "bearer secret")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("POST /mcp: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusUnauthorized {
		t.Error("lowercase bearer scheme was rejected")
	}
}

func TestMCPWithBearerToken(t *testing.T) {
	ts := httptest.NewServer(newTestHandler(t, "secret"))
	t.Cleanup(ts.Close)

	httpClient := &http.Client{Transport: &bearerRoundTripper{token: "secret"}}
	cs := connectHTTP(t, ts.URL+"/mcp", httpClient)

	res, err := cs.CallTool(context.Background(), &mcp.CallToolParams{
		Name:      "get_page_by_id",
		Arguments: map[string]any{"id": 1},
	})
	if err != nil {
		t.Fatalf("CallTool() error = %v", err)
	}
	if res.IsError {
		t.Fatalf("IsError = true: %v", res.Content)
	}
}

func TestMCPWithoutAuthToken(t *testing.T) {
	ts := httptest.NewServer(newTestHandler(t, ""))
	t.Cleanup(ts.Close)

	cs := connectHTTP(t, ts.URL+"/mcp", ts.Client())

	res, err := cs.ListTools(context.Background(), nil)
	if err != nil {
		t.Fatalf("ListTools() error = %v", err)
	}
	if len(res.Tools) != 4 {
		t.Errorf("tools = %d, want 4", len(res.Tools))
	}
}

func TestServeHTTPRefusesNonLoopbackWithoutAuth(t *testing.T) {
	err := ServeHTTP(context.Background(), HTTPOptions{
		Addr:      "0.0.0.0:0",
		Path:      "/mcp",
		Logger:    testLogger(),
		NewServer: func(*http.Request) *mcp.Server { return newBareServer() },
	})
	if err == nil {
		t.Fatal("ServeHTTP() error = nil, want refusal")
	}
	if !strings.Contains(err.Error(), "non-loopback") {
		t.Errorf("error = %q, want non-loopback refusal", err)
	}
}

func TestServeHTTPShutdown(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	done := make(chan error, 1)
	go func() {
		done <- ServeHTTP(ctx, HTTPOptions{
			Addr:      "127.0.0.1:0",
			Path:      "/mcp",
			Logger:    testLogger(),
			NewServer: func(*http.Request) *mcp.Server { return newBareServer() },
		})
	}()

	time.Sleep(100 * time.Millisecond)
	cancel()

	select {
	case err := <-done:
		if err != nil {
			t.Fatalf("ServeHTTP() error = %v", err)
		}
	case <-time.After(5 * time.Second):
		t.Fatal("ServeHTTP() did not stop after cancellation")
	}
}

func newBareServer() *mcp.Server {
	return mcp.NewServer(&mcp.Implementation{Name: "test", Version: "0"}, nil)
}

func connectHTTP(t *testing.T, endpoint string, httpClient *http.Client) *mcp.ClientSession {
	t.Helper()

	client := mcp.NewClient(&mcp.Implementation{Name: "test-client", Version: "0"}, nil)
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	t.Cleanup(cancel)

	cs, err := client.Connect(ctx, &mcp.StreamableClientTransport{
		Endpoint:             endpoint,
		HTTPClient:           httpClient,
		DisableStandaloneSSE: true,
	}, nil)
	if err != nil {
		t.Fatalf("client connect: %v", err)
	}
	t.Cleanup(func() { _ = cs.Close() })
	return cs
}

type bearerRoundTripper struct {
	token string
}

func (t *bearerRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
	req = req.Clone(req.Context())
	req.Header.Set("Authorization", "Bearer "+t.token)
	return http.DefaultTransport.RoundTrip(req)
}