package array

import (
	"errors"
	"reflect"
	"testing"
)

func TestMapWithError(t *testing.T) {
	t.Run("success case", func(t *testing.T) {
		// Arrange
		input := []int{1, 2, 3}
		expected := []string{"1", "2", "3"}

		// Act
		result, err := MapWithError(input, func(val int, index int) (*string, error) {
			str := string(rune(val + '0'))
			return &str, nil
		})

		// Assert
		if err != nil {
			t.Errorf("Expected no error, got %v", err)
		}
		if !reflect.DeepEqual(result, expected) {
			t.Errorf("Expected %v, got %v", expected, result)
		}
	})

	t.Run("error case", func(t *testing.T) {
		// Arrange
		input := []int{1, 2, 3}
		testErr := errors.New("test error")

		// Act
		result, err := MapWithError(input, func(val int, index int) (*string, error) {
			if val == 2 {
				return nil, testErr
			}
			str := string(rune(val + '0'))
			return &str, nil
		})

		// Assert
		if err != testErr {
			t.Errorf("Expected error %v, got %v", testErr, err)
		}
		if result != nil {
			t.Errorf("Expected nil result, got %v", result)
		}
	})

	t.Run("empty array", func(t *testing.T) {
		// Arrange
		var input []int

		// Act
		result, err := MapWithError(input, func(val int, index int) (*string, error) {
			str := string(rune(val + '0'))
			return &str, nil
		})

		// Assert
		if err != nil {
			t.Errorf("Expected no error, got %v", err)
		}
		if len(result) != 0 {
			t.Errorf("Expected empty result, got %v", result)
		}
	})
}

func TestMap(t *testing.T) {
	t.Run("basic transformation", func(t *testing.T) {
		// Arrange
		input := []int{1, 2, 3}
		expected := []string{"1", "2", "3"}

		// Act
		result := Map(input, func(val int, index int) string {
			return string(rune(val + '0'))
		})

		// Assert
		if !reflect.DeepEqual(result, expected) {
			t.Errorf("Expected %v, got %v", expected, result)
		}
	})

	t.Run("use index in transformation", func(t *testing.T) {
		// Arrange
		input := []string{"a", "b", "c"}
		expected := []string{"a0", "b1", "c2"}

		// Act
		result := Map(input, func(val string, index int) string {
			return val + string(rune(index+'0'))
		})

		// Assert
		if !reflect.DeepEqual(result, expected) {
			t.Errorf("Expected %v, got %v", expected, result)
		}
	})

	t.Run("empty array", func(t *testing.T) {
		// Arrange
		var input []int

		// Act
		result := Map(input, func(val int, index int) string {
			return string(rune(val + '0'))
		})

		// Assert
		if len(result) != 0 {
			t.Errorf("Expected empty result, got %v", result)
		}
	})
}

func TestMapD(t *testing.T) {
	t.Run("map dictionary to array", func(t *testing.T) {
		// Arrange
		input := map[string]int{
			"a": 1,
			"b": 2,
			"c": 3,
		}

		// Act
		result := MapD(input, func(val int, key string) string {
			return key + string(rune(val+'0'))
		})

		// Assert
		// Since map iteration order is not guaranteed, we check that all expected elements are in the result
		expectedElements := []string{"a1", "b2", "c3"}
		if len(result) != len(expectedElements) {
			t.Errorf("Expected result length %d, got %d", len(expectedElements), len(result))
		}

		resultMap := make(map[string]bool)
		for _, v := range result {
			resultMap[v] = true
		}

		for _, expected := range expectedElements {
			if !resultMap[expected] {
				t.Errorf("Expected result to contain %s, but it doesn't", expected)
			}
		}
	})

	t.Run("empty map", func(t *testing.T) {
		// Arrange
		input := map[string]int{}

		// Act
		result := MapD(input, func(val int, key string) string {
			return key + string(rune(val+'0'))
		})

		// Assert
		if len(result) != 0 {
			t.Errorf("Expected empty result, got %v", result)
		}
	})
}

func TestForEach(t *testing.T) {
	t.Run("modify array in place", func(t *testing.T) {
		// Arrange
		input := []int{1, 2, 3}
		expected := []int{2, 3, 4}

		// Act
		ForEach(input, func(val *int, index int) {
			*val += 1
		})

		// Assert
		if !reflect.DeepEqual(input, expected) {
			t.Errorf("Expected %v, got %v", expected, input)
		}
	})

	t.Run("use index in modification", func(t *testing.T) {
		// Arrange
		input := []int{1, 2, 3}
		expected := []int{1, 3, 5}

		// Act
		ForEach(input, func(val *int, index int) {
			*val = *val + index
		})

		// Assert
		if !reflect.DeepEqual(input, expected) {
			t.Errorf("Expected %v, got %v", expected, input)
		}
	})

	t.Run("empty array", func(t *testing.T) {
		// Arrange
		var input []int
		callCount := 0

		// Act
		ForEach(input, func(val *int, index int) {
			callCount++
		})

		// Assert
		if callCount != 0 {
			t.Errorf("Expected callback not to be called, but it was called %d times", callCount)
		}
	})
}

func TestMapMany(t *testing.T) {
	t.Run("basic flat mapping", func(t *testing.T) {
		// Arrange
		input := []int{1, 2}
		expected := []string{"1a", "1b", "2a", "2b"}

		// Act
		result := MapMany(input,
			func(i int) []string {
				return []string{"a", "b"}
			},
			func(i int, s string) *string {
				res := string(rune(i+'0')) + s
				return &res
			})

		// Assert
		if !reflect.DeepEqual(result, expected) {
			t.Errorf("Expected %v, got %v", expected, result)
		}
	})

	t.Run("with nil results", func(t *testing.T) {
		// Arrange
		input := []int{1, 2, 3}
		expected := []string{"1a", "2a", "3a"}

		// Act
		result := MapMany(input,
			func(i int) []string {
				return []string{"a", "b"}
			},
			func(i int, s string) *string {
				if s == "b" {
					return nil
				}
				res := string(rune(i+'0')) + s
				return &res
			})

		// Assert
		if !reflect.DeepEqual(result, expected) {
			t.Errorf("Expected %v, got %v", expected, result)
		}
	})

	t.Run("empty input array", func(t *testing.T) {
		// Arrange
		var input []int

		// Act
		result := MapMany(input,
			func(i int) []string {
				return []string{"a", "b"}
			},
			func(i int, s string) *string {
				res := string(rune(i+'0')) + s
				return &res
			})

		// Assert
		if len(result) != 0 {
			t.Errorf("Expected empty result, got %v", result)
		}
	})
}

func TestMapManyD(t *testing.T) {
	t.Run("map dictionary to flattened array", func(t *testing.T) {
		// Arrange
		input := map[string]int{
			"a": 1,
			"b": 2,
		}

		// Act
		result := MapManyD(input,
			func(val int) []string {
				return []string{"x", "y"}
			},
			func(s string) string {
				return s + "z"
			})

		// Assert
		// Since map iteration order is not guaranteed, we check that all expected elements are in the result
		expectedElements := []string{"xz", "yz", "xz", "yz"}
		if len(result) != len(expectedElements) {
			t.Errorf("Expected result length %d, got %d", len(expectedElements), len(result))
		}

		resultMap := make(map[string]int)
		for _, v := range result {
			resultMap[v]++
		}

		if resultMap["xz"] != 2 || resultMap["yz"] != 2 {
			t.Errorf("Expected result to contain 2 of each 'xz' and 'yz', got %v", resultMap)
		}
	})

	t.Run("empty inner collection", func(t *testing.T) {
		// Arrange
		input := map[string]int{
			"a": 1,
			"b": 2,
		}

		// Act
		result := MapManyD(input,
			func(val int) []string {
				return []string{}
			},
			func(s string) string {
				return s + "z"
			})

		// Assert
		if len(result) != 0 {
			t.Errorf("Expected empty result, got %v", result)
		}
	})

	t.Run("empty input map", func(t *testing.T) {
		// Arrange
		input := map[string]int{}

		// Act
		result := MapManyD(input,
			func(val int) []string {
				return []string{"x", "y"}
			},
			func(s string) string {
				return s + "z"
			})

		// Assert
		if len(result) != 0 {
			t.Errorf("Expected empty result, got %v", result)
		}
	})
}