From 3febe6601cca5c9b64fdc52ccf74e8ca7d521ab7 Mon Sep 17 00:00:00 2001
From: Arthur Lu <learthurgo@gmail.com>
Date: Mon, 27 Feb 2023 01:28:01 +0000
Subject: [PATCH] add basic local db utility functions

---
 .gitignore |  3 ++-
 db.js      | 46 ++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/.gitignore b/.gitignore
index 9790e9b..2e965cb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 **/package-lock.json
 **/node_modules
-**/vars.js
\ No newline at end of file
+**/vars.js
+**/localdb.json
\ No newline at end of file
diff --git a/db.js b/db.js
index 17f2776..b474c53 100644
--- a/db.js
+++ b/db.js
@@ -2,10 +2,19 @@ const fs = require("fs");
 
 filename = "localdb.json";
 
+let db = {};
+
 /**
  * called at app startup, can be used to initialize any variables needed for database access
  */
-function init () {}
+function init () {
+	try {
+		db = fs.readFileSync(filename);
+	}
+	catch {
+		fs.writeFileSync(filename, JSON.stringify(db));
+	}
+}
 
 /**
  * user requests additional resources specified in k-v pairs
@@ -13,7 +22,14 @@ function init () {}
  * @param {Object} resources k-v pairs with resource name as keys and resource ammount as values
  * @returns {boolean} whether the user is approved to allocate requested resources
  */
-function requestResources (user, resources) {}
+function requestResources (user, resources) {
+	Object.keys(resources).forEach((element) => {
+		if (db[user][element] < resources[element]) {
+			return false;
+		}
+	});
+	return true;
+}
 
 /**
  * user allocates additional resources specified in k-v pairs
@@ -21,7 +37,18 @@ function requestResources (user, resources) {}
  * @param {Object} resources k-v pairs with resource name as keys and resource ammount as values
  * @returns {boolean} true if resources were successfully allocated, false otherwise
  */
-function allocateResources (user, resources) {}
+function allocateResources (user, resources) {
+	Object.keys(resources).forEach((element) => {
+		db[user][element] -= resource[element];
+	});
+	try {
+		fs.writeFileSync(filename, db);
+		return true;
+	}
+	catch {
+		return false;
+	}
+}
 
 /**
  * user releases allocated resources specified in k-v pairs
@@ -29,6 +56,17 @@ function allocateResources (user, resources) {}
  * @param {Object} resources k-v pairs with resource name as keys and resource ammount as values
  * @returns {boolean} true if resources were successfully deallocated, false otherwise
  */
-function releaseResources (user, resources) {}
+function releaseResources (user, resources) {
+	Object.keys(resources).forEach((element) => {
+		db[user][element] += resource[element];
+	});
+	try {
+		fs.writeFileSync(filename, db);
+		return true;
+	}
+	catch {
+		return false;
+	}
+}
 
 module.exports = {init, requestResources, releaseResources};
\ No newline at end of file