package api

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

// newTestTodoistClient creates a TodoistClient for testing with custom base URL
func newTestTodoistClient(baseURL, apiKey string) *TodoistClient {
	client := NewTodoistClient(apiKey)
	client.BaseURL = baseURL
	return client
}

func TestTodoistClient_CreateTask(t *testing.T) {
	// Mock server
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Verify method and path
		if r.Method != "POST" {
			t.Errorf("Expected POST request, got %s", r.Method)
		}
		if r.URL.Path != "/tasks" {
			t.Errorf("Expected path /tasks, got %s", r.URL.Path)
		}

		// Verify Authorization header
		if !strings.HasPrefix(r.Header.Get("Authorization"), "Bearer ") {
			t.Errorf("Expected Bearer token in Authorization header")
		}

		// Parse JSON body
		var payload map[string]interface{}
		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
			t.Errorf("Failed to decode request body: %v", err)
		}

		// Verify content
		if payload["content"] != "Test Task" {
			t.Errorf("Expected content=Test Task, got %v", payload["content"])
		}

		if payload["project_id"] != "project-123" {
			t.Errorf("Expected project_id=project-123, got %v", payload["project_id"])
		}

		// Return mock response
		response := todoistTaskResponse{
			ID:          "task-456",
			Content:     "Test Task",
			Description: "",
			ProjectID:   "project-123",
			Priority:    1,
			Labels:      []string{},
			URL:         "https://todoist.com/task/456",
			CreatedAt:   time.Now().Format(time.RFC3339),
		}

		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(response)
	}))
	defer server.Close()

	// Create client with mock server URL
	client := newTestTodoistClient(server.URL, "test-key")

	// Test CreateTask
	ctx := context.Background()
	task, err := client.CreateTask(ctx, "Test Task", "project-123", nil, 0)

	if err != nil {
		t.Fatalf("CreateTask failed: %v", err)
	}

	// Verify response
	if task.ID != "task-456" {
		t.Errorf("Expected task ID task-456, got %s", task.ID)
	}
	if task.Content != "Test Task" {
		t.Errorf("Expected task content Test Task, got %s", task.Content)
	}
	if task.ProjectID != "project-123" {
		t.Errorf("Expected project ID project-123, got %s", task.ProjectID)
	}
}

func TestTodoistClient_CreateTask_WithDueDate(t *testing.T) {
	dueDate := time.Date(2026, 1, 15, 0, 0, 0, 0, time.UTC)

	// Mock server
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Parse JSON body
		var payload map[string]interface{}
		_ = json.NewDecoder(r.Body).Decode(&payload)

		// Verify due_date
		if payload["due_date"] != "2026-01-15" {
			t.Errorf("Expected due_date=2026-01-15, got %v", payload["due_date"])
		}

		// Return mock response with due date
		response := todoistTaskResponse{
			ID:        "task-789",
			Content:   "Task with Due Date",
			ProjectID: "project-456",
			URL:       "https://todoist.com/task/789",
			CreatedAt: time.Now().Format(time.RFC3339),
			Due: &dueInfo{
				Date:     "2026-01-15",
				Datetime: "",
			},
		}

		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(response)
	}))
	defer server.Close()

	// Create client
	client := newTestTodoistClient(server.URL, "test-key")

	// Test CreateTask with due date
	ctx := context.Background()
	task, err := client.CreateTask(ctx, "Task with Due Date", "project-456", &dueDate, 0)

	if err != nil {
		t.Fatalf("CreateTask failed: %v", err)
	}

	// Verify due date is set
	if task.DueDate == nil {
		t.Error("Expected due date to be set")
	} else {
		expectedDate := time.Date(2026, 1, 15, 0, 0, 0, 0, time.UTC)
		if !task.DueDate.Equal(expectedDate) {
			t.Errorf("Expected due date %v, got %v", expectedDate, *task.DueDate)
		}
	}
}

func TestParseDueDate_LocalDatetimeInDateField(t *testing.T) {
	// Todoist REST API v1 puts local datetime (no tz offset) in the "date" field
	// when datetime is not in UTC (e.g. recurring tasks with a set time)
	// e.g. due={date="2026-03-22T19:00:00" datetime="" is_recurring=true}
	due := &dueInfo{
		Date:        "2026-03-22T19:00:00",
		Datetime:    "",
		IsRecurring: true,
	}
	result := parseDueDate(due)
	if result == nil {
		t.Fatal("parseDueDate returned nil for date field containing local datetime — must parse YYYY-MM-DDTHH:MM:SS format")
	}
	if result.Hour() != 19 || result.Minute() != 0 {
		t.Errorf("Expected 19:00, got %02d:%02d", result.Hour(), result.Minute())
	}
}

func TestParseDueDate_MicrosecondDatetime(t *testing.T) {
	// Todoist REST API v1 returns datetime with microseconds: "2023-01-15T10:00:00.000000Z"
	// time.RFC3339 cannot parse fractional seconds — parseDueDate must use RFC3339Nano
	due := &dueInfo{
		Date:        "2023-01-15",
		Datetime:    "2023-01-15T10:00:00.000000Z",
		IsRecurring: true,
	}
	result := parseDueDate(due)
	if result == nil {
		t.Fatal("parseDueDate returned nil for datetime with microseconds — RFC3339Nano required")
	}
	if result.Hour() != 10 || result.Minute() != 0 {
		t.Errorf("Expected 10:00, got %02d:%02d", result.Hour(), result.Minute())
	}
}

func TestParseDueDate_RFC3339Datetime(t *testing.T) {
	// Standard RFC3339 without fractional seconds should also work
	due := &dueInfo{
		Date:     "2023-01-15",
		Datetime: "2023-01-15T10:00:00Z",
	}
	result := parseDueDate(due)
	if result == nil {
		t.Fatal("parseDueDate returned nil for standard RFC3339 datetime")
	}
}

func TestTodoistClient_UsesAPIv1BaseURL(t *testing.T) {
	client := NewTodoistClient("test-key")
	const want = "https://api.todoist.com/api/v1"
	if client.BaseURL != want {
		t.Errorf("expected base URL %q, got %q — Todoist REST v2 is deprecated (HTTP 410)", want, client.BaseURL)
	}
}

func TestTodoistClient_CompleteTask(t *testing.T) {
	// Mock server
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Verify method and path
		if r.Method != "POST" {
			t.Errorf("Expected POST request, got %s", r.Method)
		}
		expectedPath := "/tasks/task-123/close"
		if r.URL.Path != expectedPath {
			t.Errorf("Expected path %s, got %s", expectedPath, r.URL.Path)
		}

		// Verify Authorization header
		if !strings.HasPrefix(r.Header.Get("Authorization"), "Bearer ") {
			t.Errorf("Expected Bearer token in Authorization header")
		}

		// Return 204 No Content
		w.WriteHeader(http.StatusNoContent)
	}))
	defer server.Close()

	// Create client
	client := newTestTodoistClient(server.URL, "test-key")

	// Test CompleteTask
	ctx := context.Background()
	err := client.CompleteTask(ctx, "task-123")

	if err != nil {
		t.Fatalf("CompleteTask failed: %v", err)
	}
}

func TestTodoistClient_CompleteTask_Error(t *testing.T) {
	// Mock server that returns error
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusNotFound)
		_, _ = w.Write([]byte(`{"error":"Task not found"}`))
	}))
	defer server.Close()

	// Create client
	client := newTestTodoistClient(server.URL, "test-key")

	// Test CompleteTask with error
	ctx := context.Background()
	err := client.CompleteTask(ctx, "invalid-task")

	if err == nil {
		t.Error("Expected error, got nil")
	}
	if !strings.Contains(err.Error(), "404") {
		t.Errorf("Expected error to contain status 404, got: %v", err)
	}
}

func TestTodoistClient_GetProjects(t *testing.T) {
	// Mock server
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Verify method and path
		if r.Method != "GET" {
			t.Errorf("Expected GET request, got %s", r.Method)
		}
		if r.URL.Path != "/projects" {
			t.Errorf("Expected path /projects, got %s", r.URL.Path)
		}

		// Return mock response
		response := todoistProjectsPage{
			Results: []todoistProjectResponse{
				{ID: "proj-1", Name: "Project 1"},
				{ID: "proj-2", Name: "Project 2"},
			},
		}

		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(response)
	}))
	defer server.Close()

	// Create client
	client := newTestTodoistClient(server.URL, "test-key")

	// Test GetProjects
	ctx := context.Background()
	projects, err := client.GetProjects(ctx)

	if err != nil {
		t.Fatalf("GetProjects failed: %v", err)
	}

	// Verify response
	if len(projects) != 2 {
		t.Errorf("Expected 2 projects, got %d", len(projects))
	}

	if projects[0].ID != "proj-1" || projects[0].Name != "Project 1" {
		t.Errorf("Project 1 mismatch: got ID=%s Name=%s", projects[0].ID, projects[0].Name)
	}

	if projects[1].ID != "proj-2" || projects[1].Name != "Project 2" {
		t.Errorf("Project 2 mismatch: got ID=%s Name=%s", projects[1].ID, projects[1].Name)
	}
}

func TestTodoistClient_GetTasks(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != "GET" {
			t.Errorf("Expected GET, got %s", r.Method)
		}

		w.Header().Set("Content-Type", "application/json")

		// GetTasks also calls GetProjects internally
		if r.URL.Path == "/projects" {
			response := todoistProjectsPage{
				Results: []todoistProjectResponse{
					{ID: "proj-1", Name: "Project 1"},
				},
			}
			json.NewEncoder(w).Encode(response)
			return
		}

		if r.URL.Path == "/tasks" {
			response := todoistTasksPage{
				Results: []todoistTaskResponse{
					{ID: "task-1", Content: "Task 1", ProjectID: "proj-1", CreatedAt: time.Now().Format(time.RFC3339)},
					{ID: "task-2", Content: "Task 2", ProjectID: "proj-1", CreatedAt: time.Now().Format(time.RFC3339)},
				},
			}
			json.NewEncoder(w).Encode(response)
			return
		}

		t.Errorf("Unexpected path: %s", r.URL.Path)
	}))
	defer server.Close()

	client := newTestTodoistClient(server.URL, "test-key")
	tasks, err := client.GetTasks(context.Background())
	if err != nil {
		t.Fatalf("GetTasks failed: %v", err)
	}

	if len(tasks) != 2 {
		t.Errorf("Expected 2 tasks, got %d", len(tasks))
	}
}

func TestTodoistClient_ReopenTask(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != "POST" {
			t.Errorf("Expected POST, got %s", r.Method)
		}
		expectedPath := "/tasks/task-123/reopen"
		if r.URL.Path != expectedPath {
			t.Errorf("Expected path %s, got %s", expectedPath, r.URL.Path)
		}

		w.WriteHeader(http.StatusNoContent)
	}))
	defer server.Close()

	client := newTestTodoistClient(server.URL, "test-key")
	err := client.ReopenTask(context.Background(), "task-123")
	if err != nil {
		t.Fatalf("ReopenTask failed: %v", err)
	}
}

func TestTodoistClient_UpdateTask(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != "POST" {
			t.Errorf("Expected POST, got %s", r.Method)
		}
		expectedPath := "/tasks/task-123"
		if r.URL.Path != expectedPath {
			t.Errorf("Expected path %s, got %s", expectedPath, r.URL.Path)
		}

		var payload map[string]interface{}
		json.NewDecoder(r.Body).Decode(&payload)
		if payload["content"] != "Updated Content" {
			t.Errorf("Expected content 'Updated Content', got %v", payload["content"])
		}

		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(map[string]string{"id": "task-123"})
	}))
	defer server.Close()

	client := newTestTodoistClient(server.URL, "test-key")
	err := client.UpdateTask(context.Background(), "task-123", map[string]interface{}{"content": "Updated Content"})
	if err != nil {
		t.Fatalf("UpdateTask failed: %v", err)
	}
}