add: date-based template variables

src/LogLevel.ts

@@ -1,7 +1,30 @@
+import { padNum } from "./padNum";
 import { padStr } from "./padStr";
 
+const weekdays = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
+const months = [
+  "Jan",
+  "Feb",
+  "Mar",
+  "Apr",
+  "May",
+  "Jun",
+  "Jul",
+  "Aug",
+  "Sep",
+  "Oct",
+  "Nov",
+  "Dec"
+];
+const ordSuffix = ["st", "nd", "rd"];
+
 type ColorFormatter = (str: string) => string;
 
+interface MessageTemplate {
+  template: string;
+  utc?: boolean;
+}
+
 interface LogLevelOpts {
   /**
    * Name of the log level
@@ -25,12 +48,29 @@ interface LogLevelOpts {
   color?: ColorFormatter;
 }
 
+function toTemplateObjs(
+  msgVal: string | MessageTemplate,
+  fileMsgVal?: string | MessageTemplate
+) {
+  const msgTemplate: MessageTemplate =
+    typeof msgVal == "string"
+      ? { template: msgVal, utc: false }
+      : { ...msgVal };
+
+  const fileMsgTemplate: MessageTemplate = fileMsgVal
+    ? typeof fileMsgVal == "string"
+      ? { template: fileMsgVal, utc: false }
+      : { ...fileMsgVal }
+    : msgTemplate;
+  return { msg: msgTemplate, file: fileMsgTemplate };
+}
+
 export class LogLevel {
   #name: string;
-  #msgTemplate: string;
-  #fileMsgTemplate: string;
+  #templates: ReturnType<typeof toTemplateObjs>;
   #padLen: number;
   #color?: ColorFormatter;
+  #now: Date;
 
   constructor({
     name,
@@ -40,20 +80,87 @@ export class LogLevel {
     color
   }: LogLevelOpts) {
     this.#name = name;
-    this.#msgTemplate = msgTemplate;
-    this.#fileMsgTemplate = fileMsgTemplate || msgTemplate;
+    this.#templates = toTemplateObjs(msgTemplate, fileMsgTemplate);
     this.#padLen = padLen || 0;
     this.#color = color;
+    this.#now = new Date();
   }
 
-  #processTemplateVar(str: string /* , now: Date*/) {
-    switch (str) {
-      case "%name%":
-        return this.#name.toLowerCase();
-      case "%NAME%":
-        return this.#name.toUpperCase();
-      case "%Name%":
-        return this.#name;
+  #processTemplateVar(str: string, utc: boolean): string {
+    const now = this.#now;
+    const r = (str: string) => this.#processTemplateVar(`%${str}%`, utc); // call this method recursively
+
+    switch (str.toLowerCase()) {
+      case "%year%":
+      case "%#year%":
+        return now[utc ? "getUTCFullYear" : "getFullYear"]().toString();
+
+      case "%month%":
+        return (now[utc ? "getUTCMonth" : "getMonth"]() + 1).toString();
+      case "%#month%":
+        return padNum(r("month"), 2);
+
+      case "%date%":
+        return now[utc ? "getUTCDate" : "getDate"]().toString();
+      case "%#date%":
+        return padNum(r("date"), 2);
+
+      case "%hour%":
+      case "%hours%":
+        return now[utc ? "getUTCHours" : "getHours"]().toString();
+
+      case "%#hour%":
+      case "%#hours%":
+        return padNum(r("hour"), 2);
+
+      case "%min%":
+      case "%mins%":
+      case "%minute%":
+      case "%minutes%":
+        return now[utc ? "getUTCMinutes" : "getMinutes"]().toString();
+
+      case "%#min%":
+      case "%#mins%":
+      case "%#minute%":
+      case "%#minutes%":
+        return padNum(r("min"), 2);
+
+      case "%sec%":
+      case "%second%":
+      case "%seconds%":
+        return now[utc ? "getUTCSeconds" : "getSeconds"]().toString();
+
+      case "%#sec%":
+      case "%#second%":
+      case "%#seconds%":
+        return padNum(r("sec"), 2);
+
+      case "%day%":
+        return weekdays[now[utc ? "getUTCDay" : "getDay"]()];
+
+      case "%month_str%":
+        return months[now[utc ? "getUTCMonth" : "getMonth"]()];
+
+      case "%date_ord%": {
+        const date = now[utc ? "getUTCDate" : "getDate"]();
+        const suffix =
+          (4 <= date && date <= 20) || (24 <= date && date <= 30)
+            ? "th"
+            : ordSuffix[(date % 10) - 1];
+        return date + suffix;
+      }
+
+      case "%iso%":
+      case "%iso_short%":
+        return `${r("year")}-${r("#month")}-${r("#date")}`;
+
+      case "%iso_full%":
+      case "%iso_long%":
+        return now.toISOString();
+
+      case "%time%":
+        return `${r("#hour")}:${r("#min")}:${r("#sec")}`;
+
       default:
         return str;
     }
@@ -65,8 +172,9 @@ export class LogLevel {
     let val = this.#name;
 
     if (str.startsWith("%#")) direction = "left";
-    if (str.endsWith("#%"))
+    if (str.endsWith("#%")) {
       direction = direction == "left" ? "center" : "right";
+    }
 
     switch (tag) {
       case "name":
@@ -82,17 +190,20 @@ export class LogLevel {
     return direction ? padStr(val, this.#padLen, direction) : val;
   }
 
-  #processPrefix(template: string, isFileLog?: boolean) {
-    //const now = new Date();
+  #processPrefix({ template, utc }: MessageTemplate, isFileLog?: boolean) {
+    this.#now = new Date();
+
     return template
       .replace(/%#?(?:name|Name|NAME)#?%/g, str =>
         this.#processNameVar(str, isFileLog)
       )
-      .replace(/%[a-z]+%/gi, str => this.#processTemplateVar(str /*, now*/));
+      .replace(/%#?[a-z_]+%/gi, str =>
+        this.#processTemplateVar(str, utc ?? false)
+      );
   }
 
   processTemplate(msg: string, isFileLog?: boolean) {
-    const template = isFileLog ? this.#fileMsgTemplate : this.#msgTemplate;
+    const template = this.#templates[isFileLog ? "file" : "msg"];
     const prefix = this.#processPrefix(template, isFileLog);
     return `${prefix} ${msg}`;
   }

src/padNum.ts

@@ -0,0 +1,3 @@
+export function padNum(num: number | string, len: number) {
+  return num.toString().padStart(len, "0");
+}

tests/LogLevel.test.ts

@@ -70,6 +70,19 @@ test("processTemplate - Does not transform unknown variables", () => {
   assert.is(level.processTemplate("foo"), "%wrong% test: foo");
 });
 
+test("processTemplate - Dates", () => {
+  const level = new LogLevel({
+    name: "test",
+    msgTemplate: { template: "[%iso% %time%] %name% -", utc: true }
+  });
+  assert.ok(
+    /^\[\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}] test -/.test(
+      level.processTemplate("foo")
+    ),
+    "test template with %iso% and %time% using regex"
+  );
+});
+
 test("processTemplate - name colour", () => {
   const level = new LogLevel({
     name: "test",