package service_test

import (
	"context"
	"testing"

	"financeiro-carvalho/internal/model"
	"financeiro-carvalho/internal/repository"
	"financeiro-carvalho/internal/service"
)

// mockCategoryRepo implements repository.CategoryRepository in memory.
type mockCategoryRepo struct {
	categories   []model.Category
	txCount      map[int]int // category_id → transaction count
}

func newMockRepo(cats []model.Category) *mockCategoryRepo {
	return &mockCategoryRepo{categories: cats, txCount: map[int]int{}}
}

func (m *mockCategoryRepo) List(_ context.Context) ([]model.Category, error) {
	return m.categories, nil
}

func (m *mockCategoryRepo) GetByID(_ context.Context, id int) (*model.Category, error) {
	for _, c := range m.categories {
		if c.ID == id {
			cp := c
			return &cp, nil
		}
	}
	return nil, repository.ErrNotFound
}

func (m *mockCategoryRepo) Create(_ context.Context, name, color string, _ bool, _ *float64) (*model.Category, error) {
	c := model.Category{ID: len(m.categories) + 1, Name: name, Color: color}
	m.categories = append(m.categories, c)
	return &c, nil
}

func (m *mockCategoryRepo) Update(_ context.Context, id int, name, color string, _ bool, _ *float64) (*model.Category, error) {
	for i, c := range m.categories {
		if c.ID == id {
			m.categories[i].Name = name
			m.categories[i].Color = color
			cp := m.categories[i]
			return &cp, nil
		}
	}
	return nil, repository.ErrNotFound
}

func (m *mockCategoryRepo) Delete(_ context.Context, id int) error {
	for i, c := range m.categories {
		if c.ID == id {
			m.categories = append(m.categories[:i], m.categories[i+1:]...)
			return nil
		}
	}
	return repository.ErrNotFound
}

func (m *mockCategoryRepo) HasTransactions(_ context.Context, id int) (bool, error) {
	return m.txCount[id] > 0, nil
}

// ── tests ──────────────────────────────────────────────────────────────────────

func TestDeleteDefaultCategory_Rejected(t *testing.T) {
	repo := newMockRepo([]model.Category{
		{ID: 1, Name: "Saúde", Color: "#EF4444", IsDefault: true},
	})
	svc := service.NewCategoryService(repo)

	err := svc.Delete(context.Background(), 1)
	if err != service.ErrDefaultCategory {
		t.Fatalf("expected ErrDefaultCategory, got %v", err)
	}
}

func TestDeleteCategoryWithTransactions_Rejected(t *testing.T) {
	repo := newMockRepo([]model.Category{
		{ID: 2, Name: "Lazer", Color: "#10B981", IsDefault: false},
	})
	repo.txCount[2] = 3
	svc := service.NewCategoryService(repo)

	err := svc.Delete(context.Background(), 2)
	if err != service.ErrHasTransactions {
		t.Fatalf("expected ErrHasTransactions, got %v", err)
	}
}

func TestDeleteUserCategory_OK(t *testing.T) {
	repo := newMockRepo([]model.Category{
		{ID: 3, Name: "Minha Cat", Color: "#123456", IsDefault: false},
	})
	svc := service.NewCategoryService(repo)

	if err := svc.Delete(context.Background(), 3); err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
}

func TestCreateCategory_EmptyName_Rejected(t *testing.T) {
	svc := service.NewCategoryService(newMockRepo(nil))
	_, err := svc.Create(context.Background(), model.CategoryInput{Name: "  ", Color: "#123456"})
	if err != service.ErrEmptyName {
		t.Fatalf("expected ErrEmptyName, got %v", err)
	}
}

func TestCreateCategory_InvalidColor_Rejected(t *testing.T) {
	svc := service.NewCategoryService(newMockRepo(nil))
	_, err := svc.Create(context.Background(), model.CategoryInput{Name: "X", Color: "red"})
	if err != service.ErrInvalidColor {
		t.Fatalf("expected ErrInvalidColor, got %v", err)
	}
}

func TestCreateCategory_OK(t *testing.T) {
	svc := service.NewCategoryService(newMockRepo(nil))
	cat, err := svc.Create(context.Background(), model.CategoryInput{Name: "Nova", Color: "#AABBCC"})
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if cat.Name != "Nova" || cat.Color != "#AABBCC" {
		t.Fatalf("unexpected result: %+v", cat)
	}
}