feat : sélecteur d'année sur l'onglet Congés de la fiche employé

Permet de consulter les exercices passés (calendrier + compteurs) sur
l'onglet Congés. La plage proposée est bornée par max(début historique
contrat, RTT_START_DATE) pour ne pas remonter avant la mise en service
du logiciel. Édition des stocks N-1 et fractionnés verrouillée sur
exercices clos.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/composables/useEmployeeLeave.ts

@@ -7,27 +7,91 @@ import { listAbsences } from '~/services/absences'
 import { getEmployeeLeaveSummary, updateFractionedDays, updatePaidLeaveDays } from '~/services/employee-leave-summary'
 import { listPublicHolidays } from '~/services/public-holidays'
 
+export type LeaveYearOption = {
+  value: number
+  label: string
+}
+
 export const useEmployeeLeave = (employee: Ref<Employee | null>, reloadEmployee: () => Promise<void>) => {
   const employeeAbsences = ref<Absence[]>([])
   const leaveSummary = ref<EmployeeLeaveSummary | null>(null)
   const publicHolidays = ref<Record<string, string>>({})
   const isLeaveLoading = ref(false)
   const leaveDataLoaded = ref(false)
+  const selectedLeaveYear = ref<number | null>(null)
 
-  const getLeaveYear = () => {
-    const now = new Date()
-    const isForfait = employee.value?.contract?.type === CONTRACT_TYPES.FORFAIT
-    return isForfait
-      ? now.getFullYear()
-      : (now.getMonth() >= 5 ? now.getFullYear() + 1 : now.getFullYear())
+  const isForfaitContract = (emp: Employee | null) =>
+    emp?.contract?.type === CONTRACT_TYPES.FORFAIT
+
+  const computeLeaveYearForDate = (emp: Employee | null, date: Date): number => {
+    if (isForfaitContract(emp)) return date.getFullYear()
+    return date.getMonth() >= 5 ? date.getFullYear() + 1 : date.getFullYear()
+  }
+
+  const currentLeaveYear = computed<number | null>(() => {
+    if (!employee.value) return null
+    return computeLeaveYearForDate(employee.value, new Date())
+  })
+
+  const formatLeaveYearLabel = (year: number, isForfait: boolean): string => {
+    if (isForfait) return String(year)
+    return `Juin ${year - 1} → Mai ${year}`
+  }
+
+  const availableLeaveYears = computed<LeaveYearOption[]>(() => {
+    if (!employee.value || currentLeaveYear.value === null) return []
+    const isForfait = isForfaitContract(employee.value)
+    const current = currentLeaveYear.value
+
+    const startDates: string[] = []
+    for (const period of employee.value.contractHistory ?? []) {
+      if (period.startDate) startDates.push(period.startDate)
+    }
+    if (employee.value.entryDate) startDates.push(employee.value.entryDate)
+
+    let contractFloor = current
+    for (const raw of startDates) {
+      const date = new Date(`${raw.substring(0, 10)}T00:00:00`)
+      if (Number.isNaN(date.getTime())) continue
+      const leaveYear = computeLeaveYearForDate(employee.value, date)
+      if (leaveYear < contractFloor) contractFloor = leaveYear
+    }
+
+    // Hard floor : data-start-date (env RTT_START_DATE) — le logiciel n'a pas
+    // d'historique avant cette date, inutile de proposer des années antérieures.
+    let dataFloor: number | null = null
+    const dataStart = leaveSummary.value?.dataStartDate
+    if (dataStart) {
+      const dataStartDate = new Date(`${dataStart.substring(0, 10)}T00:00:00`)
+      if (!Number.isNaN(dataStartDate.getTime())) {
+        dataFloor = computeLeaveYearForDate(employee.value, dataStartDate)
+      }
+    }
+
+    const minYear = dataFloor !== null ? Math.max(contractFloor, dataFloor) : contractFloor
+
+    const years: LeaveYearOption[] = []
+    for (let y = current; y >= minYear; y -= 1) {
+      years.push({ value: y, label: formatLeaveYearLabel(y, isForfait) })
+    }
+    return years
+  })
+
+  const initSelectedLeaveYear = () => {
+    if (selectedLeaveYear.value !== null) return
+    if (currentLeaveYear.value !== null) {
+      selectedLeaveYear.value = currentLeaveYear.value
+    }
   }
 
   const loadLeaveData = async () => {
     if (!employee.value || isLeaveLoading.value) return
+    initSelectedLeaveYear()
+    if (selectedLeaveYear.value === null) return
     isLeaveLoading.value = true
     try {
-      const isForfait = employee.value.contract?.type === CONTRACT_TYPES.FORFAIT
-      const leaveYear = getLeaveYear()
+      const isForfait = isForfaitContract(employee.value)
+      const leaveYear = selectedLeaveYear.value
       const from = isForfait ? `${leaveYear}-01-01` : `${leaveYear - 1}-06-01`
       const to = isForfait ? `${leaveYear}-12-31` : `${leaveYear}-05-31`
       const holidayYears = isForfait ? [leaveYear] : [leaveYear - 1, leaveYear]
@@ -46,8 +110,16 @@ export const useEmployeeLeave = (employee: Ref<Employee | null>, reloadEmployee:
     }
   }
 
+  const setSelectedLeaveYear = async (year: number) => {
+    if (selectedLeaveYear.value === year) return
+    selectedLeaveYear.value = year
+    leaveDataLoaded.value = false
+    await loadLeaveData()
+  }
+
   const resetLoaded = () => {
     leaveDataLoaded.value = false
+    selectedLeaveYear.value = null
   }
 
   const submitFractionedDays = async (days: number) => {
@@ -70,6 +142,10 @@ export const useEmployeeLeave = (employee: Ref<Employee | null>, reloadEmployee:
     publicHolidays,
     isLeaveLoading,
     leaveDataLoaded,
+    selectedLeaveYear,
+    currentLeaveYear,
+    availableLeaveYears,
+    setSelectedLeaveYear,
     loadLeaveData,
     resetLoaded,
     submitFractionedDays,