From 8e466d82f3e8307d6b605a1295e7da4204a995c9 Mon Sep 17 00:00:00 2001
From: Hugo Saracino <hugo@inato.com>
Date: Mon, 6 Jul 2020 15:18:39 +0200
Subject: [PATCH] =?UTF-8?q?=F0=9F=94=A7=20Add=20utilitary=20Failure=20type?=
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---
 package.json   |  3 +-
 src/Failure.ts | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++
 yarn.lock      |  5 +++
 3 files changed, 96 insertions(+), 1 deletion(-)
 create mode 100644 src/Failure.ts

diff --git a/package.json b/package.json
index e2c549e..e128c73 100644
--- a/package.json
+++ b/package.json
@@ -15,6 +15,7 @@
     "test": "jest --runInBand"
   },
   "dependencies": {
+    "decod": "^6.1.6",
     "fp-ts": "^2.6.7",
     "tslib": "^2.0.0"
   },
@@ -27,4 +28,4 @@
     "ts-jest": "^26.1.1",
     "typescript": "^3.9.6"
   }
-}
\ No newline at end of file
+}
diff --git a/src/Failure.ts b/src/Failure.ts
new file mode 100644
index 0000000..29c8b8b
--- /dev/null
+++ b/src/Failure.ts
@@ -0,0 +1,89 @@
+import * as decod from 'decod';
+import * as Either from 'fp-ts/lib/Either';
+import * as TaskEither from 'fp-ts/lib/TaskEither';
+import * as Task from 'fp-ts/lib/Task';
+import { pipe } from 'fp-ts/lib/pipeable';
+
+const decodeErrorMessage = decod.at('message', decod.string);
+
+export enum FailureType {
+  Unexpected = 'FailureType_Unexpected',
+}
+
+export type UnexpectedFailure = Failure<FailureType.Unexpected>;
+
+export class Failure<T extends string = FailureType> {
+  constructor({
+    reason,
+    type,
+    originalError,
+  }: {
+    reason: string;
+    type: T;
+    originalError?: Error | unknown;
+  }) {
+    this.reason = reason;
+    this.type = type;
+    if (originalError instanceof Error) {
+      this.originalError = originalError;
+    }
+  }
+
+  reason: string;
+
+  type: T;
+
+  originalError?: Error;
+
+  toError(): Error {
+    if (this.originalError) return this.originalError;
+    return new Error(this.reason);
+  }
+
+  static builder<T extends string>(type: T) {
+    return (reason: string, originalError?: Error | unknown) =>
+      new Failure<T>({
+        reason,
+        type,
+        originalError,
+      });
+  }
+
+  static unexpected = Failure.builder(FailureType.Unexpected);
+
+  static fromUnknownError(originalError: unknown | Error): UnexpectedFailure {
+    return Failure.unexpected(decodeErrorMessage(originalError), originalError);
+  }
+
+  static toType<T extends string>(type: T): (failure: Failure) => Failure<T> {
+    return (failure: Failure) =>
+      new Failure({
+        reason: failure.reason,
+        type,
+        originalError: failure.originalError,
+      });
+  }
+
+  static toUnexpected = Failure.toType(FailureType.Unexpected);
+
+  private static throw = (failure: Failure) => {
+    throw failure.toError();
+  };
+
+  static eitherUnsafeGet = <A>(either: Either.Either<Failure, A>): A =>
+    pipe(either, Either.getOrElseW(Failure.throw));
+
+  static taskEitherUnsafeGet = <A>(
+    taskEither: TaskEither.TaskEither<Failure, A>,
+  ): Task.Task<A> =>
+    pipe(
+      taskEither,
+      TaskEither.getOrElseW((failure) => async () => Failure.throw(failure)),
+    );
+}
+
+export type FailureTypes<F extends Record<string, string>> = F[keyof F];
+export interface FailureTypings<F extends Record<string, string>> {
+  types: FailureTypes<F>;
+  failure: Failure<FailureTypes<F>>;
+}
diff --git a/yarn.lock b/yarn.lock
index 14559ca..601bef2 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1159,6 +1159,11 @@ decimal.js@^10.2.0:
   resolved "https://registry.yarnpkg.com/decimal.js/-/decimal.js-10.2.0.tgz#39466113a9e036111d02f82489b5fd6b0b5ed231"
   integrity sha512-vDPw+rDgn3bZe1+F/pyEwb1oMG2XTlRVgAa6B4KccTEpYgF8w6eQllVbQcfIJnZyvzFtFpxnpGtx8dd7DJp/Rw==
 
+decod@^6.1.6:
+  version "6.1.6"
+  resolved "https://registry.yarnpkg.com/decod/-/decod-6.1.6.tgz#de2b7d2c96fc16e7b429bacfc80dc71dc4191967"
+  integrity sha512-0NccOCIlq/serE+b38GayxgAiUUjpoC7jNt9PH5Ak7QTOo5GhN1owtqkfNMd3RqhNb61lg/i5BqKSF/5Hb1z3A==
+
 decode-uri-component@^0.2.0:
   version "0.2.0"
   resolved "https://registry.yarnpkg.com/decode-uri-component/-/decode-uri-component-0.2.0.tgz#eb3913333458775cb84cd1a1fae062106bb87545"