feat: initial boilerplate

api/libraries/logger/logger.ts

@@ -0,0 +1,95 @@
+import { chalk } from "./chalk.ts";
+import { type Level, logLevel } from "./level.ts";
+
+export class Logger {
+  #level: Level = "info";
+  #config: Config;
+
+  constructor(config: Config) {
+    this.#config = config;
+  }
+
+  get #prefix(): [string?] {
+    if (this.#config.prefix !== undefined) {
+      return [chalk.bold(chalk.green(this.#config.prefix))];
+    }
+    return [];
+  }
+
+  /**
+   * Set the highest logging level in the order of debug, info, warn, error.
+   *
+   * When value is 'info', info, warn and error will be logged and debug
+   * will be ignored.
+   *
+   * @param value Highest log level.
+   */
+  level(value: Level): this {
+    this.#level = value;
+    return this;
+  }
+
+  /**
+   * Returns a new logger instance with the given name as prefix.
+   *
+   * @param name - Prefix name.
+   */
+  prefix(name: string): Logger {
+    return new Logger({ prefix: name, loggers: this.#config.loggers }).level(this.#level);
+  }
+
+  /**
+   * Emit a debug message to terminal.
+   */
+  debug(...args: any[]) {
+    if (this.#isLevelEnabled(0)) {
+      console.log(new Date(), chalk.bold("Debug"), ...this.#prefix, ...args.map(this.#toFormattedArg));
+    }
+  }
+
+  /**
+   * Emit a info message to terminal.
+   */
+  info(...args: any[]) {
+    if (this.#isLevelEnabled(1)) {
+      console.log(new Date(), chalk.bold(chalk.blue("Info")), ...this.#prefix, ...args.map(this.#toFormattedArg));
+    }
+  }
+
+  /**
+   * Emit a warning message to terminal.
+   */
+  warn(...args: any[]) {
+    if (this.#isLevelEnabled(2)) {
+      console.log(new Date(), chalk.bold(chalk.orange("Warning")), ...this.#prefix, ...args.map(this.#toFormattedArg));
+    }
+  }
+
+  /**
+   * Emit a errpr message to terminal.
+   */
+  error(...args: any[]) {
+    if (this.#isLevelEnabled(3)) {
+      console.log(new Date(), chalk.bold(chalk.red("Error")), ...this.#prefix, ...args.map(this.#toFormattedArg));
+    }
+  }
+
+  #isLevelEnabled(level: 0 | 1 | 2 | 3): boolean {
+    return level >= logLevel[this.#level];
+  }
+
+  #toFormattedArg = (arg: any): string => {
+    for (const logger of this.#config.loggers) {
+      const res = logger(arg, this.#level);
+      if (res !== undefined) {
+        return res;
+      }
+    }
+    return arg;
+  };
+}
+
+type Config = {
+  prefix?: string;
+  loggers: ((arg: any, level: Level) => any)[];
+};