1 files changed, 96 insertions, 0 deletions
diff --git a/bot/log.py b/bot/log.py
new file mode 100644
index 00000000..29e696e0
--- /dev/null
+++ b/bot/log.py
@@ -0,0 +1,96 @@
+import logging
+import logging.handlers
+import os
+import sys
+from pathlib import Path
+
+import coloredlogs
+
+from bot.constants import Client
+
+
+def setup() -> None:
+    """Set up loggers."""
+    # Configure the "TRACE" logging level (e.g. "log.trace(message)")
+    logging.TRACE = 5
+    logging.addLevelName(logging.TRACE, "TRACE")
+    logging.Logger.trace = _monkeypatch_trace
+
+    format_string = "%(asctime)s | %(name)s | %(levelname)s | %(message)s"
+    log_format = logging.Formatter(format_string)
+    root_logger = logging.getLogger()
+
+    if Client.file_logs:
+        # Set up file logging
+        log_file = Path("logs/sir-lancebot.log")
+        log_file.parent.mkdir(exist_ok=True)
+
+        # File handler rotates logs every 5 MB
+        file_handler = logging.handlers.RotatingFileHandler(
+            log_file, maxBytes=5 * (2 ** 20), backupCount=10, encoding="utf-8",
+        )
+        file_handler.setFormatter(log_format)
+        root_logger.addHandler(file_handler)
+
+    if "COLOREDLOGS_LEVEL_STYLES" not in os.environ:
+        coloredlogs.DEFAULT_LEVEL_STYLES = {
+            **coloredlogs.DEFAULT_LEVEL_STYLES,
+            "trace": {"color": 246},
+            "critical": {"background": "red"},
+            "debug": coloredlogs.DEFAULT_LEVEL_STYLES["info"],
+        }
+
+    if "COLOREDLOGS_LOG_FORMAT" not in os.environ:
+        coloredlogs.DEFAULT_LOG_FORMAT = format_string
+
+    coloredlogs.install(level=logging.TRACE, stream=sys.stdout)
+
+    root_logger.setLevel(logging.DEBUG if Client.debug else logging.INFO)
+    # Silence irrelevant loggers
+    logging.getLogger("discord").setLevel(logging.ERROR)
+    logging.getLogger("websockets").setLevel(logging.ERROR)
+    logging.getLogger("PIL").setLevel(logging.ERROR)
+    logging.getLogger("matplotlib").setLevel(logging.ERROR)
+    logging.getLogger("async_rediscache").setLevel(logging.WARNING)
+
+    _set_trace_loggers()
+
+    root_logger.info("Logging initialization complete")
+
+
+def _monkeypatch_trace(self: logging.Logger, msg: str, *args, **kwargs) -> None:
+    """
+    Log 'msg % args' with severity 'TRACE'.
+
+    To pass exception information, use the keyword argument exc_info with a true value, e.g.
+    logger.trace("Houston, we have an %s", "interesting problem", exc_info=1)
+    """
+    if self.isEnabledFor(logging.TRACE):
+        self._log(logging.TRACE, msg, args, **kwargs)
+
+
+def _set_trace_loggers() -> None:
+    """
+    Set loggers to the trace level according to the value from the BOT_TRACE_LOGGERS env var.
+
+    When the env var is a list of logger names delimited by a comma,
+    each of the listed loggers will be set to the trace level.
+
+    If this list is prefixed with a "!", all of the loggers except the listed ones will be set to the trace level.
+
+    Otherwise if the env var begins with a "*",
+    the root logger is set to the trace level and other contents are ignored.
+    """
+    level_filter = Client.trace_loggers
+    if level_filter:
+        if level_filter.startswith("*"):
+            logging.getLogger().setLevel(logging.TRACE)
+
+        elif level_filter.startswith("!"):
+            logging.getLogger().setLevel(logging.TRACE)
+            for logger_name in level_filter.strip("!,").split(","):
+                logging.getLogger(logger_name).setLevel(logging.DEBUG)
+
+        else:
+            for logger_name in level_filter.strip(",").split(","):
+                logging.getLogger(logger_name).setLevel(logging.TRACE)