Deal with out-of-bounds years

src/App.tsx

@@ -1,7 +1,7 @@
 import React from 'react';
 import './App.css';
 import {Calendar} from './Calendar';
-import {gregorianJDN, jdnFrench, Month} from "./dates";
+import {frSupportedYear, gregorianJDN, jdnFrench, Month} from "./dates";
 
 type YearMonth = {
     year: number;
@@ -14,9 +14,10 @@ function parseURL(): YearMonth | null {
         return null;
 
     const month = +match[2];
-    if (month < 1 || month > 13)
+    const year = +match[1];
+    if (!frSupportedYear(year) || month < 1 || month > 13)
         return null;
-    return {year: +match[1], month: month as Month};
+    return {year: year, month: month as Month};
 }
 
 type AppState = YearMonth & {

src/Calendar.tsx

@@ -4,13 +4,15 @@ import {
     dateName,
     Day,
     decadeNames,
+    endYear,
     frIsLeap,
     frJDN,
     jdnFrench,
     jdnGregorian,
     jdnLongCount,
     Month,
-    monthName
+    monthName,
+    startYear
 } from './dates';
 
 type MonthProps = {
@@ -116,6 +118,14 @@ export class Calendar extends React.Component<CalendarProps, CalendarState> {
             month -= 13;
         }
 
+        if (year < startYear) {
+            year = startYear;
+            month = 1;
+        } else if (year > endYear) {
+            year = endYear;
+            month = 13;
+        }
+
         this.props.onSwitch && this.props.onSwitch(year, month as Month);
     }
 
@@ -150,13 +160,13 @@ export class Calendar extends React.Component<CalendarProps, CalendarState> {
     }
 
     monthChange(event: any) {
-        this.props.onSwitch && this.props.onSwitch(this.props.year, event.target.value as Month);
+        this.goToNormalized(this.props.year, event.target.value as Month);
     }
 
     yearChange(event: any) {
         console.log(/^-?\d+/.test(event.target.value));
         if (/^-?\d+/.test(event.target.value)) {
-            this.props.onSwitch && this.props.onSwitch(+event.target.value, this.props.month);
+            this.goToNormalized(+event.target.value, this.props.month);
         }
         this.setState({yearStr: event.target.value});
     }
@@ -202,7 +212,7 @@ export class Calendar extends React.Component<CalendarProps, CalendarState> {
                       })
                   }</select>
                   <input type="number" className="Calendar-year-input form-control" value={this.state.yearStr}
-                         onChange={this.yearChange.bind(this)}/>
+                         onChange={this.yearChange.bind(this)} min={startYear} max={endYear}/>
                   <button type="button" className="form-control btn btn-primary Calendar-today-button"
                           onClick={this.goToToday.bind(this)}>Today
                   </button>

src/dates.ts

@@ -63,15 +63,21 @@ export const decadeNames = [
 ];
 
 const startJD = data.start_jd;
-const startYear = data.start_year;
+export const startYear = data.start_year;
 const leaps: Array<number> = [0];
 
 let leapFromStart = 0;
 data.leap.forEach(leap => {
     leapFromStart += leap;
     leaps.push(leapFromStart);
+
 });
 
+export const endYear = startYear + leaps.length - 1;
+export function frSupportedYear(year: number): boolean {
+    return startYear <= year && year <= endYear;
+}
+
 export function gregorianJDN(year: number, month: number, day: number): number {
     const g = year + 4716 - (month <= 2 ? 1 : 0);
     const f = (month + 9) % 12;