feat(web): add client-side logging support

Also modified langauge-web/src/main/js/xtext/ServiceBuilder.js to make
sure the new logger is used as soon as xtext is initialized.

1 files changed, 49 insertions, 0 deletions

diff --git a/language-web/src/main/js/logging.tsx b/language-web/src/main/js/logging.tsx
new file mode 100644
index 00000000..25f50f19
--- /dev/null
+++ b/language-web/src/main/js/logging.tsx
@@ -0,0 +1,49 @@
+import styles, { CSPair } from 'ansi-styles';
+import log from 'loglevel';
+import * as prefix from 'loglevel-plugin-prefix';
+
+const colors: Record<string, CSPair> = {
+  TRACE: styles.magenta,
+  DEBUG: styles.cyan,
+  INFO: styles.blue,
+  WARN: styles.yellow,
+  ERROR: styles.red,
+};
+
+prefix.reg(log);
+
+if (DEBUG) {
+  log.setLevel(log.levels.DEBUG);
+} else {
+  log.setLevel(log.levels.WARN);
+}
+
+if ('chrome' in window) {
+  // Only Chromium supports console ANSI escape sequences.
+  prefix.apply(log, {
+    format(level, name, timestamp) {
+      const formattedTimestamp = `${styles.gray.open}[${timestamp.toString()}]${styles.gray.close}`;
+      const levelColor = colors[level.toUpperCase()] || styles.red;
+      const formattedLevel = `${levelColor.open}${level}${levelColor.close}`;
+      const formattedName = `${styles.green.open}(${name || 'root'})${styles.green.close}`;
+      return `${formattedTimestamp} ${formattedLevel} ${formattedName}`;
+    },
+  });
+} else {
+  prefix.apply(log, {
+    template: '[%t] %l (%n)',
+  });
+}
+
+const appLogger = log.getLogger(PACKAGE_NAME);
+
+appLogger.info('Version:', PACKAGE_NAME, PACKAGE_VERSION);
+appLogger.info('Debug mode:', DEBUG);
+
+export function getLoggerFromRoot(name: string | symbol): log.Logger {
+  return log.getLogger(name);
+}
+
+export function getLogger(name: string | symbol): log.Logger {
+  return getLoggerFromRoot(`${PACKAGE_NAME}.${name.toString()}`);
+}