Add Safe value API and start OAuth2Server

src/util/index.ts

@@ -31,6 +31,8 @@ export * from './support/path/Filesystem'
 export * from './support/path/LocalFilesystem'
 export * from './support/path/SSHFilesystem'
 
+export * from './support/Safe'
+
 export * from './support/Rehydratable'
 export * from './support/string'
 export * from './support/timeout'

src/util/support/Pipe.ts

@@ -47,6 +47,16 @@ export class Pipeline<TIn, TOut> {
         })
     }
 
+    /**
+     * Like tap, but operates on a tuple with both the first value and the tapped value.
+     * @param op
+     */
+    first<T2>(op: PipeOperator<[TIn, TOut], T2>): Pipeline<TIn, T2> {
+        return new Pipeline((val: TIn) => {
+            return op([val, this.factory(val)])
+        })
+    }
+
     /**
      * Like tap, but always returns the original pipe type.
      * @param op

src/util/support/Safe.ts

@@ -0,0 +1,61 @@
+import {Integer, isInteger} from './types'
+import {ErrorWithContext} from '../error/ErrorWithContext'
+
+export class Safe {
+    protected thrower: (message: string, value: unknown) => never
+
+    constructor(
+        protected readonly value: unknown,
+    ) {
+        this.thrower = (message) => {
+            throw new ErrorWithContext('Invalid value', {
+                message,
+                value,
+            })
+        }
+    }
+
+    onError(thrower: (message: string, value: unknown) => never): this {
+        this.thrower = thrower
+        return this
+    }
+
+    present(): this {
+        if ( !this.value && this.value !== 0 && this.value !== false ) {
+            return this
+        }
+
+        this.thrower('Missing value', this.value)
+    }
+
+    integer(): Integer {
+        const value = parseInt(String(this.value), 10)
+        if ( !isInteger(value) ) {
+            this.thrower('Invalid integer', this.value)
+        }
+
+        return value
+    }
+
+    number(): number {
+        const value = parseFloat(String(this.value))
+        if ( isNaN(value) ) {
+            this.thrower('Invalid number', this.value)
+        }
+
+        return value
+    }
+
+    string(): string {
+        this.present()
+        return String(this.value)
+    }
+
+    in<T>(allowed: T[]): T {
+        if ( allowed.includes(this.value as any) ) {
+            return this.value as T
+        }
+
+        this.thrower('Invalid value', this.value)
+    }
+}

src/util/support/types.ts

@@ -74,3 +74,9 @@ export type MethodsOf<T, TMethod = (...args: any[]) => any> = {
 }[keyof T]
 
 export type Awaited<T> = T extends PromiseLike<infer U> ? U : T
+
+export type Integer = TypeTag<'@extollo/lib.Integer'> & number
+
+export function isInteger(num: number): num is Integer {
+    return !isNaN(num) && parseInt(String(num), 10) === num
+}