package web

import (
	"bufio"
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"image/png"
	"io"
	"net/http"
	"net/http/httptest"
	"reflect"
	"strings"
	"sync"
	"testing"
	"testing/synctest"
	"time"

	"mqtt_washingmachine/internal/sensor"
	"mqtt_washingmachine/internal/status"
)

func TestStatusAPI(t *testing.T) {
	for _, tt := range []struct {
		name, state, message string
		readings             []status.Sample
	}{
		{"startup", "waiting", "Waiting for data...", []status.Sample{}},
		{"waiting", "waiting", "Waiting for data...", []status.Sample{{Power: 47.7, Valid: true}}},
		{"incomplete", "incomplete", "Incomplete data", []status.Sample{{Power: 47.7, Valid: true}, {}, {Valid: true}}},
		{"running", "running", "Laundry not yet done", []status.Sample{{Valid: true}, {Power: 3, Valid: true}, {Valid: true}}},
		{"done", "done", "Laundry done", []status.Sample{{Power: 2.99, Valid: true}, {Valid: true}, {Valid: true}}},
	} {
		t.Run(tt.name, func(t *testing.T) {
			handler := NewHandler(func() status.Result { return status.Evaluate(tt.readings) }, &sensor.Hub{})
			response := httptest.NewRecorder()
			handler.ServeHTTP(response, httptest.NewRequest(http.MethodGet, "/api/status", nil))
			if response.Code != http.StatusOK {
				t.Fatalf("status = %d", response.Code)
			}
			if got := response.Header().Get("Content-Type"); got != "application/json" {
				t.Errorf("content type = %q", got)
			}
			if got := response.Header().Get("Cache-Control"); got != "no-store" {
				t.Errorf("cache control = %q", got)
			}
			var got status.Result
			if err := json.Unmarshal(response.Body.Bytes(), &got); err != nil {
				t.Fatal(err)
			}
			want := status.Result{State: tt.state, Message: tt.message, Readings: tt.readings}
			if !reflect.DeepEqual(got, want) {
				t.Fatalf("body = %+v; want %+v", got, want)
			}
		})
	}
}

func TestPageAndRouting(t *testing.T) {
	handler := NewHandler(func() status.Result { return status.Evaluate(nil) }, &sensor.Hub{})
	page := httptest.NewRecorder()
	handler.ServeHTTP(page, httptest.NewRequest(http.MethodGet, "/", nil))
	if page.Code != http.StatusOK || !strings.HasPrefix(page.Header().Get("Content-Type"), "text/html") {
		t.Fatalf("page response: %+v", page.Result())
	}
	for _, text := range []string{`name="viewport"`, "Waiting for data...", "/api/status", "60000", "EventSource", "/api/events", "toFixed(2)", "--", "clamp(", ".done { color: #1a7f37; }", `<title>Laundry status</title>`, `rel="manifest" href="/manifest.webmanifest"`, `name="theme-color" content="#ffffff"`, `rel="apple-touch-icon" href="/apple-touch-icon.png"`, `rel="icon" href="/icons/icon.svg" type="image/svg+xml"`} {
		if !strings.Contains(page.Body.String(), text) {
			t.Errorf("page missing %q", text)
		}
	}
	for _, tt := range []struct {
		method, path string
		code         int
	}{
		{http.MethodGet, "/missing", http.StatusNotFound},
		{http.MethodPost, "/api/status", http.StatusMethodNotAllowed},
		{http.MethodPost, "/api/events", http.StatusMethodNotAllowed},
		{http.MethodPost, "/", http.StatusMethodNotAllowed},
	} {
		response := httptest.NewRecorder()
		handler.ServeHTTP(response, httptest.NewRequest(tt.method, tt.path, nil))
		if response.Code != tt.code {
			t.Errorf("%s %s = %d; want %d", tt.method, tt.path, response.Code, tt.code)
		}
	}
}

func TestHomeScreenAssets(t *testing.T) {
	handler := NewHandler(func() status.Result { return status.Evaluate(nil) }, &sensor.Hub{})
	for _, tt := range []struct {
		path, contentType string
		size              int
	}{
		{"/manifest.webmanifest", "application/manifest+json", 0},
		{"/icons/icon.svg", "image/svg+xml", 0},
		{"/icons/icon-192.png", "image/png", 192},
		{"/icons/icon-512.png", "image/png", 512},
		{"/icons/icon-maskable-512.png", "image/png", 512},
		{"/apple-touch-icon.png", "image/png", 180},
	} {
		t.Run(tt.path, func(t *testing.T) {
			response := httptest.NewRecorder()
			handler.ServeHTTP(response, httptest.NewRequest(http.MethodGet, tt.path, nil))
			if response.Code != http.StatusOK {
				t.Fatalf("status = %d; want 200", response.Code)
			}
			if got := response.Header().Get("Content-Type"); got != tt.contentType {
				t.Errorf("content type = %q; want %q", got, tt.contentType)
			}
			if got := response.Header().Get("Cache-Control"); got != "no-cache" {
				t.Errorf("cache control = %q; want no-cache", got)
			}
			if response.Body.Len() == 0 {
				t.Fatal("empty asset")
			}
			if tt.size != 0 {
				if !bytes.HasPrefix(response.Body.Bytes(), []byte("\x89PNG\r\n\x1a\n")) {
					t.Fatal("missing PNG signature")
				}
				img, err := png.Decode(response.Body)
				if err != nil {
					t.Fatal(err)
				}
				if got := img.Bounds(); got.Dx() != tt.size || got.Dy() != tt.size {
					t.Errorf("PNG bounds = %v; want %dx%d", got, tt.size, tt.size)
				}
			}
			for _, request := range []struct {
				method, path string
				code         int
			}{
				{http.MethodPost, tt.path, http.StatusMethodNotAllowed},
				{http.MethodGet, tt.path + "/missing", http.StatusNotFound},
			} {
				response := httptest.NewRecorder()
				handler.ServeHTTP(response, httptest.NewRequest(request.method, request.path, nil))
				if response.Code != request.code {
					t.Errorf("%s %s = %d; want %d", request.method, request.path, response.Code, request.code)
				}
			}
		})
	}
}

func TestHomeScreenManifest(t *testing.T) {
	handler := NewHandler(func() status.Result { return status.Evaluate(nil) }, &sensor.Hub{})
	response := httptest.NewRecorder()
	handler.ServeHTTP(response, httptest.NewRequest(http.MethodGet, "/manifest.webmanifest", nil))
	var manifest struct {
		Name            string                                       `json:"name"`
		ShortName       string                                       `json:"short_name"`
		StartURL        string                                       `json:"start_url"`
		Scope           string                                       `json:"scope"`
		Display         string                                       `json:"display"`
		ThemeColor      string                                       `json:"theme_color"`
		BackgroundColor string                                       `json:"background_color"`
		Icons           []struct{ Src, Sizes, Type, Purpose string } `json:"icons"`
	}
	if err := json.Unmarshal(response.Body.Bytes(), &manifest); err != nil {
		t.Fatal(err)
	}
	if manifest.Name != "Home Lanundry" || manifest.ShortName != "Home Lanundry" || manifest.StartURL != "/" || manifest.Scope != "/" || manifest.Display != "standalone" || manifest.ThemeColor != "#ffffff" || manifest.BackgroundColor != "#ffffff" {
		t.Errorf("unexpected manifest: %+v", manifest)
	}
	var variants []string
	for _, icon := range manifest.Icons {
		response := httptest.NewRecorder()
		handler.ServeHTTP(response, httptest.NewRequest(http.MethodGet, icon.Src, nil))
		if response.Code != http.StatusOK || icon.Type != "image/png" || response.Header().Get("Content-Type") != icon.Type {
			t.Fatalf("icon %+v: status %d, content type %q", icon, response.Code, response.Header().Get("Content-Type"))
		}
		cfg, err := png.DecodeConfig(response.Body)
		if err != nil {
			t.Fatal(err)
		}
		if got := fmt.Sprintf("%dx%d", cfg.Width, cfg.Height); got != icon.Sizes {
			t.Errorf("icon %s: size %s; declared %s", icon.Src, got, icon.Sizes)
		}
		variants = append(variants, icon.Sizes+" "+icon.Purpose)
	}
	if want := []string{"192x192 any", "512x512 any", "512x512 maskable"}; !reflect.DeepEqual(variants, want) {
		t.Errorf("icon variants = %v; want %v", variants, want)
	}
}

func TestStatusAPIReadsCurrentSnapshot(t *testing.T) {
	var window status.Window
	handler := NewHandler(func() status.Result { return status.Evaluate(window.Readings()) }, &sensor.Hub{})
	for range 3 {
		window.Add(status.Sample{Valid: true})
		response := httptest.NewRecorder()
		handler.ServeHTTP(response, httptest.NewRequest(http.MethodGet, "/api/status", nil))
		var got status.Result
		if err := json.Unmarshal(response.Body.Bytes(), &got); err != nil {
			t.Fatal(err)
		}
		if !reflect.DeepEqual(got.Readings, window.Readings()) {
			t.Fatal("handler returned stale readings")
		}
	}
}

type trackedEvents struct {
	events     chan struct{}
	subscribed bool
	cancelled  bool
}

func (e *trackedEvents) Subscribe() (<-chan struct{}, func()) {
	e.subscribed = true
	return e.events, func() { e.cancelled = true }
}

// Synthetic time orders timer wakeups but does not establish a race-detector
// happens-before edge from a body inspection to the next timed write.
type streamRecorder struct {
	*httptest.ResponseRecorder
	mu sync.Mutex
}

func (w *streamRecorder) Write(p []byte) (int, error) {
	w.mu.Lock()
	defer w.mu.Unlock()
	return w.ResponseRecorder.Write(p)
}

func (w *streamRecorder) body() string {
	w.mu.Lock()
	defer w.mu.Unlock()
	return w.Body.String()
}

func TestEventsInitialNotificationKeepAliveAndCleanup(t *testing.T) {
	synctest.Test(t, func(t *testing.T) {
		oldInterval := keepAliveInterval
		keepAliveInterval = time.Second
		defer func() { keepAliveInterval = oldInterval }()
		events := &trackedEvents{events: make(chan struct{}, 1)}
		handler := NewHandler(func() status.Result { return status.Evaluate(nil) }, events)
		ctx, cancel := context.WithCancel(t.Context())
		defer cancel()
		request := httptest.NewRequest(http.MethodGet, "/api/events", nil).WithContext(ctx)
		response := &streamRecorder{ResponseRecorder: httptest.NewRecorder()}
		done := make(chan struct{})
		go func() { handler.ServeHTTP(response, request); close(done) }()
		synctest.Wait()
		if !events.subscribed || !response.Flushed || response.Code != http.StatusOK {
			t.Fatal("stream did not subscribe and flush immediately")
		}
		if response.Header().Get("Content-Type") != "text/event-stream" || response.Header().Get("Cache-Control") != "no-store" {
			t.Fatalf("stream headers: %v", response.Header())
		}
		if got := response.body(); got != "event: update\ndata: {}\n\n" {
			t.Fatalf("initial event = %q", got)
		}
		events.events <- struct{}{}
		synctest.Wait()
		if got := strings.Count(response.body(), "event: update\n"); got != 2 {
			t.Fatalf("update count = %d; want 2", got)
		}
		time.Sleep(time.Second)
		synctest.Wait()
		if !strings.HasSuffix(response.body(), ": keep-alive\n\n") {
			t.Fatalf("missing keep-alive: %q", response.body())
		}
		cancel()
		synctest.Wait()
		select {
		case <-done:
		default:
			t.Fatal("handler did not exit after disconnect")
		}
		if !events.cancelled {
			t.Fatal("disconnected subscriber was not removed")
		}
	})
}

type nonFlushingWriter struct{ http.ResponseWriter }

func TestEventsRejectNonFlushingWriter(t *testing.T) {
	events := &trackedEvents{events: make(chan struct{}, 1)}
	handler := NewHandler(func() status.Result { return status.Evaluate(nil) }, events)
	response := httptest.NewRecorder()
	handler.ServeHTTP(nonFlushingWriter{response}, httptest.NewRequest(http.MethodGet, "/api/events", nil))
	if response.Code != http.StatusInternalServerError || events.subscribed {
		t.Fatalf("unsupported stream: status %d, subscribed %v", response.Code, events.subscribed)
	}
}

type blockedStreamWriter struct {
	*httptest.ResponseRecorder
	started chan struct{}
	unblock chan struct{}
	once    sync.Once
	cleared bool
}

func (w *blockedStreamWriter) Write(p []byte) (int, error) {
	close(w.started)
	<-w.unblock
	return 0, errors.New("write deadline exceeded")
}

func (w *blockedStreamWriter) SetWriteDeadline(deadline time.Time) error {
	if deadline.IsZero() {
		w.cleared = true
	} else {
		w.once.Do(func() { close(w.unblock) })
	}
	return nil
}

func TestEventsCancellationInterruptsBlockedWrite(t *testing.T) {
	events := &trackedEvents{events: make(chan struct{}, 1)}
	handler := NewHandler(func() status.Result { return status.Evaluate(nil) }, events)
	ctx, cancel := context.WithCancel(t.Context())
	defer cancel()
	response := &blockedStreamWriter{ResponseRecorder: httptest.NewRecorder(), started: make(chan struct{}), unblock: make(chan struct{})}
	done := make(chan struct{})
	go func() {
		handler.ServeHTTP(response, httptest.NewRequest(http.MethodGet, "/api/events", nil).WithContext(ctx))
		close(done)
	}()
	select {
	case <-response.started:
	case <-time.After(time.Second):
		t.Fatal("stream did not start writing")
	}
	cancel()
	select {
	case <-done:
	case <-time.After(time.Second):
		response.once.Do(func() { close(response.unblock) })
		<-done
		t.Fatal("cancellation did not interrupt the blocked write")
	}
	if !events.cancelled || !response.cleared {
		t.Fatalf("cancelled=%v, write deadline cleared=%v", events.cancelled, response.cleared)
	}
}

func TestEventsSurviveWriteTimeoutAndBroadcastValidMessages(t *testing.T) {
	var hub sensor.Hub
	sampler := &sensor.Sampler{OnReceive: hub.Notify}
	server := httptest.NewUnstartedServer(NewHandler(sampler.Status, &hub))
	server.Config.WriteTimeout = 50 * time.Millisecond
	server.Start()
	defer server.Close()
	client := &http.Client{Timeout: 3 * time.Second}
	readers := make([]*bufio.Reader, 2)
	for i := range readers {
		response, err := client.Get(server.URL + "/api/events")
		if err != nil {
			t.Fatal(err)
		}
		defer response.Body.Close()
		readers[i] = bufio.NewReader(response.Body)
		assertUpdate(t, readers[i])
	}
	time.Sleep(100 * time.Millisecond)
	if err := sampler.Receive([]byte(`broken`)); err == nil {
		t.Fatal("invalid payload accepted")
	}
	if err := sampler.Receive([]byte(`{"ENERGY":{"Power":47.7}}`)); err != nil {
		t.Fatal(err)
	}
	for _, reader := range readers {
		assertUpdate(t, reader)
	}
	if server.Config.WriteTimeout != 50*time.Millisecond {
		t.Fatal("global write timeout changed")
	}
}

func assertUpdate(t *testing.T, reader io.Reader) {
	t.Helper()
	want := "event: update\ndata: {}\n\n"
	got := make([]byte, len(want))
	if _, err := io.ReadFull(reader, got); err != nil {
		t.Fatal(err)
	}
	if string(got) != want {
		t.Fatalf("event = %q; want %q", got, want)
	}
}