feat: initial commit at project root

internal/logger/logger.js

@@ -0,0 +1,52 @@
+import process from 'process';
+
+const LOG_LEVELS = {
+  debug: 0,
+  info: 1,
+  warn: 2,
+  error: 3
+};
+
+const currentLevelStr = (process.env.LOG_LEVEL || 'info').toLowerCase();
+const currentLevel = LOG_LEVELS[currentLevelStr] !== undefined ? LOG_LEVELS[currentLevelStr] : 1;
+
+const ANSI_COLORS = {
+  DEBUG: '\x1b[36mDEBUG\x1b[0m',   // Cyan
+  INFO: '\x1b[32mINFO\x1b[0m',     // Green
+  WARN: '\x1b[33mWARN\x1b[0m',     // Yellow
+  ERROR: '\x1b[31mERROR\x1b[0m'    // Red
+};
+
+/**
+ * Helper to print log structured JSON objects to stdout.
+ * @param {string} levelName 
+ * @param {string} eventName 
+ * @param {object} [attributes] 
+ */
+function writeLog(levelName, eventName, attributes = {}) {
+  const levelNum = LOG_LEVELS[levelName];
+  if (levelNum < currentLevel) {
+    return;
+  }
+
+  const levelUpper = levelName.toUpperCase();
+  const logEntry = {
+    timestamp: new Date().toISOString(),
+    level: `__COLOR_LEVEL_${levelUpper}__`,
+    event: eventName,
+    ...attributes
+  };
+
+  let jsonStr = JSON.stringify(logEntry);
+  const coloredLevel = ANSI_COLORS[levelUpper] || levelUpper;
+  jsonStr = jsonStr.replace(`"__COLOR_LEVEL_${levelUpper}__"`, `"${coloredLevel}"`);
+
+  process.stdout.write(jsonStr + '\n');
+}
+
+export const logger = {
+  debug: (event, attrs) => writeLog('debug', event, attrs),
+  info: (event, attrs) => writeLog('info', event, attrs),
+  warn: (event, attrs) => writeLog('warn', event, attrs),
+  error: (event, attrs) => writeLog('error', event, attrs)
+};