From e2372bd5b9ead39054d8c4b002518bc15429eb76 Mon Sep 17 00:00:00 2001
From: Andrii Kirmas <kirmas@phystech.edu>
Date: Tue, 19 Oct 2021 01:21:58 +0300
Subject: [PATCH] #3 Integrate `ENV_FILE` to `main`. Comment #13 application

---
 src/cli-utils.test.ts |  2 +-
 src/cli-utils.ts      |  6 +++---
 src/index.ts          | 23 ++++++++++++++++++++++-
 src/main.test.ts      | 20 ++++++++++++++++----
 src/main.ts           | 37 ++++++++++++++++++++-----------------
 src/parse.ts          |  1 +
 6 files changed, 63 insertions(+), 26 deletions(-)

diff --git a/src/cli-utils.test.ts b/src/cli-utils.test.ts
index cf7d7c3..c502152 100644
--- a/src/cli-utils.test.ts
+++ b/src/cli-utils.test.ts
@@ -17,7 +17,7 @@ describe(fromArgs.name, () => {
   ], false)).toStrictEqual([
   ]))
 
-  it("1", () => expect(fromArgs([
+  it("duplicated", () => expect(fromArgs([
     'bin/node',
     'script',
     '--env-file=xxx yyy',
diff --git a/src/cli-utils.ts b/src/cli-utils.ts
index 9c68b6f..82f9d34 100644
--- a/src/cli-utils.ts
+++ b/src/cli-utils.ts
@@ -59,7 +59,7 @@ function fromArgs<T extends boolean>(
 /**
  * @todo Consider calculation as in compose.yml
  */
-function fromPackageEnv(env: Env) {
+function fromPackageEnv(env: Readonly<Env>) {
   return fromArrayAsAssoc(
     env,
     packagePrefix,
@@ -67,7 +67,7 @@ function fromPackageEnv(env: Env) {
   )
 }
 
-function fromEnv(env: Env) {
+function fromEnv(env: Readonly<Env>) {
   return fromArrayAsAssoc(
     env,
     envPrefix,
@@ -78,7 +78,7 @@ function fromEnv(env: Env) {
 }
 
 // CONSIDER `collected: Set<string>`
-function fromArrayAsAssoc(env: Env, prefix: string, collected: string[]) {
+function fromArrayAsAssoc(env: Readonly<Env>, prefix: string, collected: string[]) {
   let i = 0
   , key = `${prefix}_${i}`
 
diff --git a/src/index.ts b/src/index.ts
index 9211e0a..1b4c679 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,6 +1,27 @@
 import { readFileSync } from "fs"
-import { main } from "./main"
+import { assigner, main, Reader } from "./main"
+
+const {assign: $assign} = Object
+
 export { parse } from "./parse"
+export { argEnv }
+export default argEnv
+
+/**
+ * **NB!** args, package and ENV are already picked
+ * @param {string[]} paths
+ * @param {*} [env] `= process.env`
+ * @param {*} [target] `= {}`
+ * @param {*} [reader] `= readFileSync`
+ */
+// TODO #4 Like `path.unshift(".env")`
+// TODO Move to a separate module
+function argEnv<T extends Record<string, unknown>>(paths: string[], env = process.env, target = {} as T, reader = readFileSync as Reader) {
+  assigner(env, paths, reader, target)
+  $assign(env, target)
+
+  return target
+}
 
 main(
   process.env,
diff --git a/src/main.test.ts b/src/main.test.ts
index 4c4bd88..803f5b8 100644
--- a/src/main.test.ts
+++ b/src/main.test.ts
@@ -2,16 +2,22 @@ import { join } from "../research/utils"
 import { main } from "./main"
 
 describe(main.name, () => {
-  it("1", () => {
+  it("demo", () => {
     const files: Record<string, string> = {
       "npm0": "OVERWRITE=true",
       "npm1": "NPM1=Loaded",
       "arg0": "ARG0=Loaded",
       "arg1": "ARG1=Loaded",
+      "env": "ENV=Loaded",
+      "env0": "ENV0=Loaded",
+      "env1": "ENV1=Loaded"
     }
     , env = {
       "npm_package_config_env_file_0": "npm0",
       "npm_package_config_env_file_1": "npm1",
+      "ENV_FILE": "env",
+      "ENV_FILE_0": "env0",
+      "ENV_FILE_1": "env1",
       "OVERWRITE": "false"
     }
     , argv = ["node", "script", "--env-file=arg0", "--env-file=arg1"]
@@ -24,12 +30,18 @@ describe(main.name, () => {
     )
 
     expect(env).toStrictEqual({
-      "npm_package_config_env_file_0": "npm0",
-      "npm_package_config_env_file_1": "npm1",
       "NPM1": "Loaded",
       "ARG0": "Loaded",
       "ARG1": "Loaded",
-      "OVERWRITE": "false"
+      "ENV": "Loaded",
+      "ENV0": "Loaded",
+      "ENV1": "Loaded",
+      "OVERWRITE": "false",
+      "npm_package_config_env_file_0": "npm0",
+      "npm_package_config_env_file_1": "npm1",
+      "ENV_FILE": "env",
+      "ENV_FILE_0": "env0",
+      "ENV_FILE_1": "env1"
     })
     expect(argv).toStrictEqual([
       "node", "script"
diff --git a/src/main.ts b/src/main.ts
index ed7cc80..5a90893 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1,17 +1,19 @@
 import {
   fromArgs,
+  fromEnv,
   fromPackageEnv
 } from "./cli-utils"
 import {
   parse
 } from "./parse"
 
-type Reader = (path: string) => string | Buffer
+export type Reader = (path: string) => string | Buffer
 
 const {assign: $assign} = Object
 
 export {
-  main
+  main,
+  assigner
 }
 
 function main(
@@ -20,21 +22,22 @@ function main(
   reader: Reader,
   deleteArgs: boolean
 ) {
-  const envPatch: Record<string, unknown> = {}
-
-  assigner(
-    env,
+  // TODO #13
+  const patches = [
+    fromEnv(env),
     fromArgs(argv, deleteArgs),
-    reader,
-    envPatch
-  )
+    fromPackageEnv(env)
+  ]
+  , {length} = patches
+  , envPatch: Record<string, unknown> = {}
 
-  assigner(
-    env,
-    fromPackageEnv(env),
-    reader,
-    envPatch
-  )
+  for (let i = 0; i < length; i++)
+    assigner(
+      env, 
+      patches[i],
+      reader,
+      envPatch
+    )
 
   $assign(env, envPatch)
 
@@ -42,8 +45,8 @@ function main(
 }
 
 function assigner(
-  env: Env,
-  files: string[],
+  env: Readonly<Env>,
+  files: readonly string[],
   reader: Reader,
   envPatch: Record<string, unknown>
 ) {
diff --git a/src/parse.ts b/src/parse.ts
index b8931bb..42bc3dc 100644
--- a/src/parse.ts
+++ b/src/parse.ts
@@ -14,6 +14,7 @@ function parse<K extends string>(
   reserved: undefined | Record<string, unknown>
 ): Record<K, string> {
   // TODO Line
+  // TODO Emit good error for bad `src`
   const source = typeof src === "string" ? src : src.toString()
   , $return = {} as Record<string, string>
   , replacer = (_: string, variable: string, __: string, $default = "") =>