package flatten_array

import "errors"

// Write a function that will flatten an array of arbitrarily nested arrays of
// integers into a flat array of integers. e.g. [[1,2,[3]],4] → [1,2,3,4]. If
// the language you're using has a function to flatten arrays, you should
// pretend it doesn't exist.

var ErrInvalidType = errors.New("Invalid type, should be int")

func FlattenArray(values []interface{}) ([]int, error) {
	result := make([]int, 0)

	for _, value := range values {
		switch value.(type) {
		case int:
			result = append(result, value.(int))
		case []interface{}:
			recursiveResult, err := FlattenArray(value.([]interface{}))
			if err != nil {
				return nil, err
			}

			result = append(result, recursiveResult...)
		case []int:
			result = append(result, value.([]int)...)
		default:
			return nil, ErrInvalidType
		}
	}

	return result, nil
}