From 7e0e4f33e879f8f6d6c11920dca8665838c146a9 Mon Sep 17 00:00:00 2001
From: Richard Lindhout <richardlindhout96@gmail.com>
Date: Fri, 3 Jul 2020 19:12:46 +0200
Subject: [PATCH] Work around limitations of Typescript with an extra tuple

---
 example/src/translate.ts | 151 +++++++++++++++++++++------------------
 1 file changed, 81 insertions(+), 70 deletions(-)

diff --git a/example/src/translate.ts b/example/src/translate.ts
index 2a51098..1cb94f8 100644
--- a/example/src/translate.ts
+++ b/example/src/translate.ts
@@ -23,84 +23,94 @@ type TranslationsObject<TGroup, TValue> = {
 
 
 type SubscriberFunc = (n:number) => any;
+type val<T> = (...params: any[]) => T
+type val1<T> = T
+type TranslationInput<TValue> = {
+    [group: string]: {
+        [key: string]:  val<TValue> | val1<TValue>
+    },
+}
 
-export function createTranslations<TValue, TGroup>(t: TGroup, po: Options<TValue>): TranslationsObject<TGroup, TValue> {
-    // subscribers with callbacks for external updates
-    let sb: SubscriberFunc[] = [];
-
-    let o = po
-    // empty map for easier translations
-    let et:any = {}
-
-    // convert
-    // {
-    //   homeScreen:{
-    //     loginButton:{
-    //       nl: 'Inloggen,
-    //       en: 'Sign in',
-    //     }
-    //   }
-    // }
-    //
-    // to =>> based on the current language
-    //
-    //   homeScreen:{
-    //     loginButton:'Sign in',
-    //   }
-    // }
-
-    function gen() {
-        // loop translations groups
-        Object.keys(t).forEach(g => {
-            // easierTranslation map with the group in the key
-            et[g] = {}
-
-            // loop translations inside group
-            // @ts-ignore
-            Object.keys(t[g]).forEach(k => {
-                // e.g. 'Sign in'
+export function createTranslations<TValue extends object>(){
+    return function <TGroup extends TranslationInput<TValue>>(t: TGroup, po: Options<TValue>): TranslationsObject<TGroup, TValue> {
+        // subscribers with callbacks for external updates
+        let sb: SubscriberFunc[] = [];
+
+        let o = po
+        // empty map for easier translations
+        let et: any = {}
+
+        // convert
+        // {
+        //   homeScreen:{
+        //     loginButton:{
+        //       nl: 'Inloggen,
+        //       en: 'Sign in',
+        //     }
+        //   }
+        // }
+        //
+        // to =>> based on the current language
+        //
+        //   homeScreen:{
+        //     loginButton:'Sign in',
+        //   }
+        // }
+
+        function gen() {
+            // loop translations groups
+            Object.keys(t).forEach(g => {
+                // easierTranslation map with the group in the key
+                et[g] = {}
+
+                // loop translations inside group
                 // @ts-ignore
-                let tv = t[g][k]
-
-                // map them in easier translation map
-                et[g][k] = tv instanceof Function ? (...p: any) => {
-                    let z = (tv as Function)(...p)
-                    return z[o.language] || z[o.fallback]
-                } : tv[o.language] || tv[o.fallback]
+                Object.keys(t[g]).forEach(k => {
+                    // e.g. 'Sign in'
+                    // @ts-ignore
+                    let tv = t[g][k]
+
+                    // map them in easier translation map
+                    et[g][k] = tv instanceof Function ? (...p: any) => {
+                        let z = (tv as Function)(...p)
+                        return z[o.language] || z[o.fallback]
+                    } : tv[o.language] || tv[o.fallback]
+                })
             })
-        })
-    }
+        }
 
-    function setOptions(op: Options<TValue>) {
-        o = op
-        gen()
+        function setOptions(op: Options<TValue>) {
+            o = op
+            gen()
 
-        // call subscribers
-        sb.forEach((c: any) => c((p:number) => p + 1));
-    }
+            // call subscribers
+            sb.forEach((c: any) => c((p: number) => p + 1));
+        }
+
+        // use hook
+        function use(): any {
+            let [, s] = R.useState<number>(0);
 
-    // use hook
-    function use(): any {
-        let [, s] = R.useState<number>(0);
+            // subscribe to changes
+            R.useEffect(() => {
+                sb.push(s);
+                return () => {
+                    sb = sb.filter((f) => f !== s);
+                };
+            }, [s]);
 
-        // subscribe to changes
-        R.useEffect(() => {
-            sb.push(s);
-            return () => {
-                sb = sb.filter((f) => f !== s);
-            };
-        }, [s]);
+            // return easier translations object
+            return et;
+        }
 
-        // return easier translations object
-        return et;
+        gen()
+        return {
+            translations: et,
+            getOptions: () => o,
+            setOptions,
+            use,
+        };
     }
-    gen()
-    return {
-        translations: et,
-        getOptions: () => o,
-        setOptions,
-        use,
-    };
 }
 
 // first describe which languages are allowed/required (Typescript)
@@ -122,7 +132,8 @@ function getBestLanguage(): typeof availableLanguages[number] | typeof fallback
 
 
 // create a translation object with your translations
-const translate = createTranslations<TranslationLanguages>({
+
+const translate = createTranslations<TranslationLanguages>()({
     appScreen:{
         yesText: {
             nl: 'Ja',