Implement structured logging using log/slog package

internal/cli/logger.go

@@ -0,0 +1,46 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package cli // import "miniflux.app/v2/internal/cli"
+
+import (
+	"io"
+	"log/slog"
+)
+
+func InitializeDefaultLogger(logLevel string, logFile io.Writer, logFormat string, logTime bool) error {
+	var programLogLevel = new(slog.LevelVar)
+	switch logLevel {
+	case "debug":
+		programLogLevel.Set(slog.LevelDebug)
+	case "info":
+		programLogLevel.Set(slog.LevelInfo)
+	case "warning":
+		programLogLevel.Set(slog.LevelWarn)
+	case "error":
+		programLogLevel.Set(slog.LevelError)
+	}
+
+	logHandlerOptions := &slog.HandlerOptions{Level: programLogLevel}
+	if !logTime {
+		logHandlerOptions.ReplaceAttr = func(groups []string, a slog.Attr) slog.Attr {
+			if a.Key == slog.TimeKey {
+				return slog.Attr{}
+			}
+
+			return a
+		}
+	}
+
+	var logger *slog.Logger
+	switch logFormat {
+	case "json":
+		logger = slog.New(slog.NewJSONHandler(logFile, logHandlerOptions))
+	default:
+		logger = slog.New(slog.NewTextHandler(logFile, logHandlerOptions))
+	}
+
+	slog.SetDefault(logger)
+
+	return nil
+}