package services

import (
	"bytes"
	"encoding/csv"
	"io"
	"testing"
	"time"

	"git.mchus.pro/mchus/quoteforge/internal/config"
)


func TestToCSV_UTF8BOM(t *testing.T) {
	svc := NewExportService(config.ExportConfig{}, nil)

	data := &ExportData{
		Name: "Test",
		Items: []ExportItem{
			{
				LotName:     "LOT-001",
				Description: "Test Item",
				Category:    "CAT",
				Quantity:    1,
				UnitPrice:   100.0,
				TotalPrice:  100.0,
			},
		},
		Total:     100.0,
		CreatedAt: time.Now(),
	}

	var buf bytes.Buffer
	if err := svc.ToCSV(&buf, data); err != nil {
		t.Fatalf("ToCSV failed: %v", err)
	}

	csvBytes := buf.Bytes()
	if len(csvBytes) < 3 {
		t.Fatalf("CSV too short to contain BOM")
	}

	// Check UTF-8 BOM: 0xEF 0xBB 0xBF
	expectedBOM := []byte{0xEF, 0xBB, 0xBF}
	actualBOM := csvBytes[:3]

	if bytes.Compare(actualBOM, expectedBOM) != 0 {
		t.Errorf("UTF-8 BOM mismatch. Expected %v, got %v", expectedBOM, actualBOM)
	}
}

func TestToCSV_SemicolonDelimiter(t *testing.T) {
	svc := NewExportService(config.ExportConfig{}, nil)

	data := &ExportData{
		Name: "Test",
		Items: []ExportItem{
			{
				LotName:     "LOT-001",
				Description: "Test Item",
				Category:    "CAT",
				Quantity:    2,
				UnitPrice:   100.50,
				TotalPrice:  201.00,
			},
		},
		Total:     201.00,
		CreatedAt: time.Now(),
	}

	var buf bytes.Buffer
	if err := svc.ToCSV(&buf, data); err != nil {
		t.Fatalf("ToCSV failed: %v", err)
	}

	// Skip BOM and read CSV with semicolon delimiter
	csvBytes := buf.Bytes()
	reader := csv.NewReader(bytes.NewReader(csvBytes[3:]))
	reader.Comma = ';'

	// Read header
	header, err := reader.Read()
	if err != nil {
		t.Fatalf("Failed to read header: %v", err)
	}

	if len(header) != 6 {
		t.Errorf("Expected 6 columns, got %d", len(header))
	}

	expectedHeader := []string{"Артикул", "Описание", "Категория", "Количество", "Цена за единицу", "Сумма"}
	for i, col := range expectedHeader {
		if i < len(header) && header[i] != col {
			t.Errorf("Column %d: expected %q, got %q", i, col, header[i])
		}
	}

	// Read item row
	itemRow, err := reader.Read()
	if err != nil {
		t.Fatalf("Failed to read item row: %v", err)
	}

	if itemRow[0] != "LOT-001" {
		t.Errorf("Lot name mismatch: expected LOT-001, got %s", itemRow[0])
	}

	if itemRow[3] != "2" {
		t.Errorf("Quantity mismatch: expected 2, got %s", itemRow[3])
	}

	if itemRow[4] != "100,50" {
		t.Errorf("Unit price mismatch: expected 100,50, got %s", itemRow[4])
	}
}

func TestToCSV_TotalRow(t *testing.T) {
	svc := NewExportService(config.ExportConfig{}, nil)

	data := &ExportData{
		Name: "Test",
		Items: []ExportItem{
			{
				LotName:     "LOT-001",
				Description: "Item 1",
				Category:    "CAT",
				Quantity:    1,
				UnitPrice:   100.0,
				TotalPrice:  100.0,
			},
			{
				LotName:     "LOT-002",
				Description: "Item 2",
				Category:    "CAT",
				Quantity:    2,
				UnitPrice:   50.0,
				TotalPrice:  100.0,
			},
		},
		Total:     200.0,
		CreatedAt: time.Now(),
	}

	var buf bytes.Buffer
	if err := svc.ToCSV(&buf, data); err != nil {
		t.Fatalf("ToCSV failed: %v", err)
	}

	csvBytes := buf.Bytes()
	reader := csv.NewReader(bytes.NewReader(csvBytes[3:]))
	reader.Comma = ';'

	// Skip header and item rows
	reader.Read()
	reader.Read()
	reader.Read()

	// Read total row
	totalRow, err := reader.Read()
	if err != nil {
		t.Fatalf("Failed to read total row: %v", err)
	}

	// Total row should have "ИТОГО:" in position 4 and total value in position 5
	if totalRow[4] != "ИТОГО:" {
		t.Errorf("Expected 'ИТОГО:' in column 4, got %q", totalRow[4])
	}

	if totalRow[5] != "200,00" {
		t.Errorf("Expected total 200,00, got %s", totalRow[5])
	}
}

func TestToCSV_CategorySorting(t *testing.T) {
	// Test category sorting without category repo (items maintain original order)
	svc := NewExportService(config.ExportConfig{}, nil)

	data := &ExportData{
		Name: "Test",
		Items: []ExportItem{
			{
				LotName:     "LOT-001",
				Category:    "CAT-A",
				Quantity:    1,
				UnitPrice:   100.0,
				TotalPrice:  100.0,
			},
			{
				LotName:     "LOT-002",
				Category:    "CAT-C",
				Quantity:    1,
				UnitPrice:   100.0,
				TotalPrice:  100.0,
			},
			{
				LotName:     "LOT-003",
				Category:    "CAT-B",
				Quantity:    1,
				UnitPrice:   100.0,
				TotalPrice:  100.0,
			},
		},
		Total:     300.0,
		CreatedAt: time.Now(),
	}

	var buf bytes.Buffer
	if err := svc.ToCSV(&buf, data); err != nil {
		t.Fatalf("ToCSV failed: %v", err)
	}

	csvBytes := buf.Bytes()
	reader := csv.NewReader(bytes.NewReader(csvBytes[3:]))
	reader.Comma = ';'

	// Skip header
	reader.Read()

	// Without category repo, items maintain original order
	row1, _ := reader.Read()
	if row1[0] != "LOT-001" {
		t.Errorf("Expected LOT-001 first, got %s", row1[0])
	}

	row2, _ := reader.Read()
	if row2[0] != "LOT-002" {
		t.Errorf("Expected LOT-002 second, got %s", row2[0])
	}

	row3, _ := reader.Read()
	if row3[0] != "LOT-003" {
		t.Errorf("Expected LOT-003 third, got %s", row3[0])
	}
}

func TestToCSV_EmptyData(t *testing.T) {
	svc := NewExportService(config.ExportConfig{}, nil)

	data := &ExportData{
		Name:      "Test",
		Items:     []ExportItem{},
		Total:     0.0,
		CreatedAt: time.Now(),
	}

	var buf bytes.Buffer
	if err := svc.ToCSV(&buf, data); err != nil {
		t.Fatalf("ToCSV failed: %v", err)
	}

	csvBytes := buf.Bytes()
	reader := csv.NewReader(bytes.NewReader(csvBytes[3:]))
	reader.Comma = ';'

	// Should have header and total row
	header, err := reader.Read()
	if err != nil {
		t.Fatalf("Failed to read header: %v", err)
	}

	if len(header) != 6 {
		t.Errorf("Expected 6 columns, got %d", len(header))
	}

	totalRow, err := reader.Read()
	if err != nil {
		t.Fatalf("Failed to read total row: %v", err)
	}

	if totalRow[4] != "ИТОГО:" {
		t.Errorf("Expected ИТОГО: in total row, got %s", totalRow[4])
	}
}

func TestToCSVBytes_BackwardCompat(t *testing.T) {
	svc := NewExportService(config.ExportConfig{}, nil)

	data := &ExportData{
		Name: "Test",
		Items: []ExportItem{
			{
				LotName:     "LOT-001",
				Description: "Test Item",
				Category:    "CAT",
				Quantity:    1,
				UnitPrice:   100.0,
				TotalPrice:  100.0,
			},
		},
		Total:     100.0,
		CreatedAt: time.Now(),
	}

	csvBytes, err := svc.ToCSVBytes(data)
	if err != nil {
		t.Fatalf("ToCSVBytes failed: %v", err)
	}

	if len(csvBytes) < 3 {
		t.Fatalf("CSV bytes too short")
	}

	// Verify BOM is present
	expectedBOM := []byte{0xEF, 0xBB, 0xBF}
	actualBOM := csvBytes[:3]
	if bytes.Compare(actualBOM, expectedBOM) != 0 {
		t.Errorf("UTF-8 BOM mismatch in ToCSVBytes")
	}
}

func TestToCSV_WriterError(t *testing.T) {
	svc := NewExportService(config.ExportConfig{}, nil)

	data := &ExportData{
		Name: "Test",
		Items: []ExportItem{
			{
				LotName:     "LOT-001",
				Description: "Test",
				Category:    "CAT",
				Quantity:    1,
				UnitPrice:   100.0,
				TotalPrice:  100.0,
			},
		},
		Total:     100.0,
		CreatedAt: time.Now(),
	}

	// Use a failing writer
	failingWriter := &failingWriter{}

	if err := svc.ToCSV(failingWriter, data); err == nil {
		t.Errorf("Expected error from failing writer, got nil")
	}
}

// failingWriter always returns an error
type failingWriter struct{}

func (fw *failingWriter) Write(p []byte) (int, error) {
	return 0, io.EOF
}