package utils

import (
	"fmt"
	"regexp"
	"strings"

	"github.com/hashicorp/terraform-plugin-framework/types/basetypes"

	"github.com/hashicorp/terraform-plugin-framework/types"
)

// ReconcileStringSlices reconciles two string lists by removing elements from the
// first list that are not in the second list and appending elements from the
// second list that are not in the first list.
// This preserves the order of the elements in the first list that are also in
// the second list, which is useful when using ListAttributes in Terraform.
// The source of truth for the order is the first list and the source of truth for the content is the second list.
func ReconcileStringSlices(list1, list2 []string) []string {
	// Create a copy of list1 to avoid modifying the original list
	list1Copy := append([]string{}, list1...)

	// Create a map to quickly check if an element is in list2
	inList2 := make(map[string]bool)
	for _, elem := range list2 {
		inList2[elem] = true
	}

	// Remove elements from list1Copy that are not in list2
	i := 0
	for _, elem := range list1Copy {
		if inList2[elem] {
			list1Copy[i] = elem
			i++
		}
	}
	list1Copy = list1Copy[:i]

	// Append elements to list1Copy that are in list2 but not in list1Copy
	inList1 := make(map[string]bool)
	for _, elem := range list1Copy {
		inList1[elem] = true
	}
	for _, elem := range list2 {
		if !inList1[elem] {
			list1Copy = append(list1Copy, elem)
		}
	}

	return list1Copy
}

func ListValuetoStringSlice(list basetypes.ListValue) ([]string, error) {
	result := []string{}
	for _, el := range list.Elements() {
		elStr, ok := el.(types.String)
		if !ok {
			return result, fmt.Errorf("expected record to be of type %T, got %T", types.String{}, elStr)
		}
		result = append(result, elStr.ValueString())
	}

	return result, nil
}

// Remove leading 0s from backup schedule numbers (e.g. "00 00 * * *" becomes "0 0 * * *")
// Needed as the API does it internally and would otherwise cause inconsistent result in Terraform
func SimplifyBackupSchedule(schedule string) string {
	regex := regexp.MustCompile(`0+\d+`) // Matches series of one or more zeros followed by a series of one or more digits
	simplifiedSchedule := regex.ReplaceAllStringFunc(schedule, func(match string) string {
		simplified := strings.TrimLeft(match, "0")
		if simplified == "" {
			simplified = "0"
		}
		return simplified
	})
	return simplifiedSchedule
}