refactor(front): extract shared utils and rewire pages

app/shared/utils/historyDisplayUtils.ts

@@ -0,0 +1,78 @@
+/**
+ * History display utilities for edit pages.
+ *
+ * Extracted from pages/component/[id]/edit.vue, pieces/[id]/edit.vue,
+ * product/[id]/edit.vue – each had an identical copy.
+ */
+
+// ---------------------------------------------------------------------------
+// Formatters
+// ---------------------------------------------------------------------------
+
+export const historyActionLabel = (action: string): string => {
+  if (action === 'create') return 'Création'
+  if (action === 'delete') return 'Suppression'
+  return 'Modification'
+}
+
+const historyDateFormatter = new Intl.DateTimeFormat('fr-FR', {
+  dateStyle: 'medium',
+  timeStyle: 'short',
+})
+
+export const formatHistoryDate = (value: string): string => {
+  const date = new Date(value)
+  if (Number.isNaN(date.getTime())) return value
+  return historyDateFormatter.format(date)
+}
+
+export const formatHistoryValue = (value: unknown): string => {
+  if (value === null || value === undefined || value === '') return '—'
+  if (Array.isArray(value)) {
+    if (value.length === 0) return '—'
+    return value.map((item) => formatHistoryValue(item)).join(', ')
+  }
+  if (typeof value === 'object') {
+    const maybeRecord = value as Record<string, unknown>
+    const name = typeof maybeRecord.name === 'string' ? maybeRecord.name : null
+    const id = typeof maybeRecord.id === 'string' ? maybeRecord.id : null
+    if (name && id) return `${name} (#${id})`
+    if (name) return name
+    if (id) return `#${id}`
+    try {
+      return JSON.stringify(value)
+    } catch {
+      return String(value)
+    }
+  }
+  return String(value)
+}
+
+// ---------------------------------------------------------------------------
+// Diff entries
+// ---------------------------------------------------------------------------
+
+interface DiffChange {
+  from?: unknown
+  to?: unknown
+}
+
+export interface HistoryDiffEntry {
+  field: string
+  label: string
+  fromLabel: string
+  toLabel: string
+}
+
+export const historyDiffEntries = (
+  entry: { diff?: Record<string, DiffChange> | null },
+  fieldLabels: Record<string, string>,
+): HistoryDiffEntry[] => {
+  const diff = entry.diff ?? {}
+  return Object.entries(diff).map(([field, change]) => ({
+    field,
+    label: fieldLabels[field] ?? field,
+    fromLabel: formatHistoryValue(change?.from),
+    toLabel: formatHistoryValue(change?.to),
+  }))
+}