1 files changed, 63 insertions, 0 deletions
diff --git a/@linaria/packages/logger/src/index.ts b/@linaria/packages/logger/src/index.ts
new file mode 100644
index 0000000..45765bb
--- /dev/null
+++ b/@linaria/packages/logger/src/index.ts
@@ -0,0 +1,63 @@
+import genericDebug from 'debug';
+import type { Debugger } from 'debug';
+
+type LogLevel = 'error' | 'warn' | 'info' | 'debug';
+
+const levels = ['error', 'warn', 'info', 'debug'];
+const currentLevel = levels.indexOf(process.env.LINARIA_LOG || 'error');
+
+const linariaLogger = genericDebug('linaria');
+
+const loggers = new Map<string, Debugger>();
+
+function gerOrCreate(namespace: string | null | undefined): Debugger {
+  if (!namespace) return linariaLogger;
+  const lastIndexOf = namespace.lastIndexOf(':');
+  if (!loggers.has(namespace)) {
+    loggers.set(
+      namespace,
+      gerOrCreate(namespace.substr(0, lastIndexOf)).extend(
+        namespace.substr(lastIndexOf + 1)
+      )
+    );
+  }
+
+  return loggers.get(namespace)!;
+}
+
+const format = <T>(text: T) => {
+  if (typeof text === 'string') {
+    return text.replace(/\n/g, '\n\t');
+  }
+
+  return text;
+};
+
+function log(
+  level: LogLevel,
+  namespaces: string,
+  arg1: any | (() => void),
+  ...restArgs: any[]
+) {
+  if (currentLevel < levels.indexOf(level)) {
+    return;
+  }
+
+  const logger = gerOrCreate(namespaces);
+  if (!logger.enabled) return;
+
+  if (typeof arg1 === 'function') {
+    const text = arg1();
+    if (text) {
+      logger('', format(text), ...restArgs);
+    }
+    return;
+  }
+
+  logger('', format(arg1), ...restArgs);
+}
+
+export const debug = log.bind(null, 'debug');
+export const info = log.bind(null, 'info');
+export const warn = log.bind(null, 'warn');
+export const error = log.bind(null, 'error');