ライブラリを番組一覧・番組ページ・再生の3段にする（ステップ12）

internal/web/natural_order.go

@@ -0,0 +1,101 @@
+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)
+}