package web

import (
	"sort"
	"strings"

	"gitea.kazu634.com/kazu634/tver/internal/store"
)

func sortJobsNaturally(jobs []store.Job) {
	sort.SliceStable(jobs, func(i, j int) bool {
		if comparison := compareNaturalTitle(jobs[i].Title, jobs[j].Title); comparison != 0 {
			return comparison < 0
		}
		left, right := jobs[i].FinishedAt, jobs[j].FinishedAt
		if left == nil || right == nil {
			if left != right {
				return left == nil
			}
		} else if !left.Equal(*right) {
			return left.Before(*right)
		}
		return jobs[i].ID < jobs[j].ID
	})
}

func compareNaturalTitle(left, right string) int {
	a, b := []rune(left), []rune(right)
	ai, bi := 0, 0
	for ai < len(a) && bi < len(b) {
		_, aIsDigit := decimalDigit(a[ai])
		_, bIsDigit := decimalDigit(b[bi])
		if aIsDigit && bIsDigit {
			var an, bn strings.Builder
			for ai < len(a) {
				digit, ok := decimalDigit(a[ai])
				if !ok {
					break
				}
				an.WriteByte(byte('0' + digit))
				ai++
			}
			for bi < len(b) {
				digit, ok := decimalDigit(b[bi])
				if !ok {
					break
				}
				bn.WriteByte(byte('0' + digit))
				bi++
			}
			if comparison := compareDecimal(an.String(), bn.String()); comparison != 0 {
				return comparison
			}
			continue
		}
		if a[ai] < b[bi] {
			return -1
		}
		if a[ai] > b[bi] {
			return 1
		}
		ai++
		bi++
	}
	if ai == len(a) && bi < len(b) {
		return -1
	}
	if bi == len(b) && ai < len(a) {
		return 1
	}
	return 0
}

func decimalDigit(r rune) (int, bool) {
	switch {
	case '0' <= r && r <= '9':
		return int(r - '0'), true
	case '０' <= r && r <= '９':
		return int(r - '０'), true
	default:
		return 0, false
	}
}

func compareDecimal(left, right string) int {
	left = strings.TrimLeft(left, "0")
	right = strings.TrimLeft(right, "0")
	if left == "" {
		left = "0"
	}
	if right == "" {
		right = "0"
	}
	if len(left) < len(right) {
		return -1
	}
	if len(left) > len(right) {
		return 1
	}
	return strings.Compare(left, right)
}