package mail

import (
	"bytes"
	"context"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/go-chi/chi/v5"

	"github.com/ultisuite/ulti-backend/internal/api/middleware"
	"github.com/ultisuite/ulti-backend/internal/api/query"
	"github.com/ultisuite/ulti-backend/internal/auth"
)

const (
	testExternalID = "ext-user-1"
	testUserID     = "user-uuid-1"
)

type fakeMailService struct {
	messages map[string]map[string]any
	deleted  map[string]bool
	sent     []sendMessageRequest
}

func newFakeMailService() *fakeMailService {
	return &fakeMailService{
		messages: map[string]map[string]any{
			"msg-1": {
				"id": "msg-1", "subject": "Hello", "snippet": "Preview text",
				"flags": []string{"unread"}, "labels": []string{"inbox"},
			},
		},
		deleted: make(map[string]bool),
	}
}

func (f *fakeMailService) ResolveUserID(_ context.Context, externalID string) (string, error) {
	if externalID != testExternalID {
		return "", ErrUserNotProvisioned
	}
	return testUserID, nil
}

func (f *fakeMailService) ListMessages(_ context.Context, externalID string, _ MessageListFilter, params query.ListParams) (MessagesList, error) {
	if externalID != testExternalID {
		return MessagesList{}, ErrUserNotProvisioned
	}
	msgs := make([]map[string]any, 0, len(f.messages))
	for id, msg := range f.messages {
		if f.deleted[id] {
			continue
		}
		msgs = append(msgs, msg)
	}
	total := int64(len(msgs))
	return MessagesList{
		Messages:   msgs,
		Page:       params.Page,
		Pagination: params.Meta(&total),
	}, nil
}

func (f *fakeMailService) GetMessage(_ context.Context, externalID, messageID string) (map[string]any, error) {
	if externalID != testExternalID {
		return nil, ErrUserNotProvisioned
	}
	if f.deleted[messageID] {
		return nil, ErrNotFound
	}
	msg, ok := f.messages[messageID]
	if !ok {
		return nil, ErrNotFound
	}
	return msg, nil
}

func (f *fakeMailService) UpdateLabels(_ context.Context, userID, messageID string, labels []string) error {
	if userID != testUserID {
		return ErrNotFound
	}
	if f.deleted[messageID] {
		return ErrNotFound
	}
	msg, ok := f.messages[messageID]
	if !ok {
		return ErrNotFound
	}
	msg["labels"] = labels
	return nil
}

func (f *fakeMailService) UpdateFlags(_ context.Context, userID, messageID string, flags []string) error {
	if userID != testUserID {
		return ErrNotFound
	}
	if f.deleted[messageID] {
		return ErrNotFound
	}
	msg, ok := f.messages[messageID]
	if !ok {
		return ErrNotFound
	}
	msg["flags"] = flags
	return nil
}

func (f *fakeMailService) DeleteMessage(_ context.Context, externalID, userID, messageID string) error {
	if externalID != testExternalID || userID != testUserID {
		return ErrNotFound
	}
	if _, ok := f.messages[messageID]; !ok || f.deleted[messageID] {
		return ErrNotFound
	}
	f.deleted[messageID] = true
	return nil
}

func (f *fakeMailService) SendMessage(_ context.Context, userID string, req *sendMessageRequest) (string, string, error) {
	if userID != testUserID {
		return "", "", ErrAccountNotFound
	}
	f.sent = append(f.sent, *req)
	return "outbox-1", "queued", nil
}

func (f *fakeMailService) ListAccounts(context.Context, string, query.ListParams) (AccountsList, error) {
	return AccountsList{}, nil
}
func (f *fakeMailService) CreateAccount(context.Context, string, *createAccountRequest) (string, error) {
	return "", nil
}
func (f *fakeMailService) GetAccount(context.Context, string, string) (map[string]any, error) {
	return nil, ErrNotFound
}
func (f *fakeMailService) DeleteAccount(context.Context, string, string) error { return nil }
func (f *fakeMailService) GetThread(context.Context, string, string) (map[string]any, error) {
	return map[string]any{"messages": []any{}}, nil
}
func (f *fakeMailService) ListRules(context.Context, string, query.ListParams) (RulesList, error) {
	return RulesList{}, nil
}
func (f *fakeMailService) CreateRule(context.Context, string, *createRuleRequest) (string, error) {
	return "", nil
}
func (f *fakeMailService) UpdateRule(context.Context, string, string, *updateRuleRequest) error {
	return nil
}
func (f *fakeMailService) DeleteRule(context.Context, string, string, string) error { return nil }
func (f *fakeMailService) ListWebhooks(context.Context, string, query.ListParams) (WebhooksList, error) {
	return WebhooksList{}, nil
}
func (f *fakeMailService) CreateWebhook(context.Context, string, *createWebhookRequest, string) (string, error) {
	return "", nil
}
func (f *fakeMailService) DeleteWebhook(context.Context, string, string, string) error { return nil }

func newTestMailRouter(svc ServiceAPI) http.Handler {
	h := NewHandlerWithService(svc)
	r := chi.NewRouter()
	r.Use(middleware.WithTestClaims(&auth.Claims{
		Sub:   testExternalID,
		Email: "user@example.com",
	}))
	r.Mount("/", h.Routes())
	return r
}

func TestListMessages(t *testing.T) {
	svc := newFakeMailService()
	router := newTestMailRouter(svc)

	req := httptest.NewRequest(http.MethodGet, "/messages", nil)
	rec := httptest.NewRecorder()
	router.ServeHTTP(rec, req)

	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want %d; body = %s", rec.Code, http.StatusOK, rec.Body.String())
	}

	var body MessagesList
	if err := json.NewDecoder(rec.Body).Decode(&body); err != nil {
		t.Fatalf("decode body: %v", err)
	}
	if len(body.Messages) != 1 {
		t.Fatalf("messages len = %d, want 1", len(body.Messages))
	}
	if body.Messages[0]["id"] != "msg-1" {
		t.Fatalf("message id = %v", body.Messages[0]["id"])
	}
}

func TestGetMessage(t *testing.T) {
	svc := newFakeMailService()
	router := newTestMailRouter(svc)

	t.Run("found", func(t *testing.T) {
		req := httptest.NewRequest(http.MethodGet, "/messages/msg-1", nil)
		rec := httptest.NewRecorder()
		router.ServeHTTP(rec, req)

		if rec.Code != http.StatusOK {
			t.Fatalf("status = %d, want %d; body = %s", rec.Code, http.StatusOK, rec.Body.String())
		}

		var body map[string]any
		if err := json.NewDecoder(rec.Body).Decode(&body); err != nil {
			t.Fatalf("decode body: %v", err)
		}
		if body["id"] != "msg-1" {
			t.Fatalf("id = %v", body["id"])
		}
	})

	t.Run("not found", func(t *testing.T) {
		req := httptest.NewRequest(http.MethodGet, "/messages/missing", nil)
		rec := httptest.NewRecorder()
		router.ServeHTTP(rec, req)

		if rec.Code != http.StatusNotFound {
			t.Fatalf("status = %d, want %d", rec.Code, http.StatusNotFound)
		}
	})
}

func TestSendMessage(t *testing.T) {
	svc := newFakeMailService()
	router := newTestMailRouter(svc)

	payload := map[string]any{
		"account_id": "acc-1",
		"to":         []string{"recipient@example.com"},
		"subject":    "Test subject",
		"body_text":  "Hello world",
	}
	body, err := json.Marshal(payload)
	if err != nil {
		t.Fatalf("marshal payload: %v", err)
	}

	req := httptest.NewRequest(http.MethodPost, "/send", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	router.ServeHTTP(rec, req)

	if rec.Code != http.StatusAccepted {
		t.Fatalf("status = %d, want %d; body = %s", rec.Code, http.StatusAccepted, rec.Body.String())
	}

	var resp map[string]string
	if err := json.NewDecoder(rec.Body).Decode(&resp); err != nil {
		t.Fatalf("decode body: %v", err)
	}
	if resp["id"] != "outbox-1" || resp["status"] != "queued" {
		t.Fatalf("response = %#v", resp)
	}
	if len(svc.sent) != 1 {
		t.Fatalf("sent count = %d, want 1", len(svc.sent))
	}
	if svc.sent[0].Subject != "Test subject" {
		t.Fatalf("sent subject = %q", svc.sent[0].Subject)
	}
}

func TestUpdateLabels(t *testing.T) {
	svc := newFakeMailService()
	router := newTestMailRouter(svc)

	body, err := json.Marshal(map[string]any{"labels": []string{"work", "important"}})
	if err != nil {
		t.Fatalf("marshal payload: %v", err)
	}

	req := httptest.NewRequest(http.MethodPut, "/messages/msg-1/labels", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	router.ServeHTTP(rec, req)

	if rec.Code != http.StatusNoContent {
		t.Fatalf("status = %d, want %d; body = %s", rec.Code, http.StatusNoContent, rec.Body.String())
	}

	labels, ok := svc.messages["msg-1"]["labels"].([]string)
	if !ok {
		t.Fatalf("labels type = %T", svc.messages["msg-1"]["labels"])
	}
	if len(labels) != 2 || labels[0] != "work" || labels[1] != "important" {
		t.Fatalf("labels = %#v", labels)
	}
}

func TestUpdateFlags(t *testing.T) {
	svc := newFakeMailService()
	router := newTestMailRouter(svc)

	body, err := json.Marshal(map[string]any{"flags": []string{"read", "starred"}})
	if err != nil {
		t.Fatalf("marshal payload: %v", err)
	}

	req := httptest.NewRequest(http.MethodPut, "/messages/msg-1/flags", bytes.NewReader(body))
	req.Header.Set("Content-Type", "application/json")
	rec := httptest.NewRecorder()
	router.ServeHTTP(rec, req)

	if rec.Code != http.StatusNoContent {
		t.Fatalf("status = %d, want %d; body = %s", rec.Code, http.StatusNoContent, rec.Body.String())
	}

	flags, ok := svc.messages["msg-1"]["flags"].([]string)
	if !ok {
		t.Fatalf("flags type = %T", svc.messages["msg-1"]["flags"])
	}
	if len(flags) != 2 || flags[0] != "read" || flags[1] != "starred" {
		t.Fatalf("flags = %#v", flags)
	}
}

func TestDeleteMessage(t *testing.T) {
	svc := newFakeMailService()
	router := newTestMailRouter(svc)

	req := httptest.NewRequest(http.MethodDelete, "/messages/msg-1", nil)
	rec := httptest.NewRecorder()
	router.ServeHTTP(rec, req)

	if rec.Code != http.StatusNoContent {
		t.Fatalf("status = %d, want %d; body = %s", rec.Code, http.StatusNoContent, rec.Body.String())
	}
	if !svc.deleted["msg-1"] {
		t.Fatal("message was not marked deleted")
	}

	// Subsequent get returns 404.
	req = httptest.NewRequest(http.MethodGet, "/messages/msg-1", nil)
	rec = httptest.NewRecorder()
	router.ServeHTTP(rec, req)
	if rec.Code != http.StatusNotFound {
		t.Fatalf("get after delete status = %d, want %d", rec.Code, http.StatusNotFound)
	}
}