feat: added logging implementation

pkg/log/log.go

@@ -0,0 +1,119 @@
+package log
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"slices"
+	"strings"
+
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+)
+
+// string representation that directly corresponds to zerolog.Level
+type LogLevel string
+type LogLevelList []LogLevel
+type LogFilter string
+
+const (
+	DEBUG    LogLevel = "debug"
+	INFO     LogLevel = "info"
+	WARN     LogLevel = "warn"
+	ERROR    LogLevel = "error"
+	DISABLED LogLevel = "disabled"
+	TRACE    LogLevel = "trace"
+)
+
+var Levels = [6]LogLevel{DEBUG, INFO, WARN, ERROR, DISABLED, TRACE}
+var LogFile *os.File
+
+func (ll LogLevel) String() string {
+	return string(ll)
+}
+
+func (ll *LogLevel) Set(v string) error {
+	switch LogLevel(v) {
+	case DEBUG, INFO, WARN, ERROR, DISABLED, TRACE:
+		*ll = LogLevel(v)
+		return nil
+	default:
+		return fmt.Errorf("must be one of %v", []LogLevel{
+			DEBUG,
+			INFO,
+			WARN,
+			ERROR,
+			DISABLED,
+			TRACE,
+		})
+	}
+}
+
+func (df LogLevel) Type() string {
+	return "LogLevel"
+}
+
+func InitWithLogLevel(logLevel LogLevel, logPath string) error {
+	var (
+		logger  zerolog.Logger
+		level   zerolog.Level
+		writer  zerolog.LevelWriter
+		writers []io.Writer
+		err     error
+	)
+
+	// set the logging level
+	level, err = strToLogLevel(logLevel)
+	if err != nil {
+		return fmt.Errorf("failed to convert log level: %v", err)
+	}
+
+	// add the default stderr writer
+	writers = append(writers, &zerolog.FilteredLevelWriter{
+		Writer: &zerolog.LevelWriterAdapter{os.Stderr},
+		Level:  level,
+	})
+
+	// add another writer to write to a log file
+	if logPath != "" {
+		LogFile, err = os.OpenFile(logPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0664)
+		if err != nil {
+			return fmt.Errorf("failed to open log file: %v", err)
+		}
+
+		// add another write to write to the specified log file
+		writers = append(writers, &zerolog.FilteredLevelWriter{
+			Writer: zerolog.LevelWriterAdapter{LogFile},
+			Level:  level,
+		})
+	}
+	writer = zerolog.MultiLevelWriter(writers...)
+	logger = zerolog.New(writer).Level(level).With().Timestamp().Caller().Logger()
+	zerolog.SetGlobalLevel(level)
+	log.Logger = logger
+	return nil
+}
+
+func strToLogLevel(ll LogLevel) (zerolog.Level, error) {
+	var tostr = func(lls []LogLevel) []string {
+		s := []string{}
+		for _, l := range lls {
+			s = append(s, string(l))
+		}
+		return s
+	}
+
+	if index := slices.Index(Levels[:], ll); index >= 0 {
+		// handle special cases to map index to DISABLED and TRACE
+		switch index {
+		case 4:
+			return zerolog.Disabled, nil
+		case 5:
+			return zerolog.TraceLevel, nil
+		}
+		return zerolog.Level(index), nil
+	}
+	return -100, fmt.Errorf(
+		"invalid log level (options: %s)", strings.Join(tostr(Levels[:]), ", "),
+	) // use 'info' by default
+}