HUGE refactor. working towards web UI

logger/slog.go

@@ -0,0 +1,189 @@
+package logger
+
+import (
+	"context"
+	"io"
+	"log/slog"
+	"os"
+	"strings"
+	"sync"
+	"time"
+
+	"arimelody.space/melody-vod-manager/colour"
+	"github.com/mattn/go-isatty"
+)
+
+type (
+	Options struct {
+		Handlers	[]slog.Handler
+		Level		slog.Leveler
+		IsTerminal	bool
+	}
+
+	SlogHandler struct {
+		attrs	[]slog.Attr
+		group	string
+		mutex	*sync.Mutex
+		options	Options
+		writer	io.Writer
+	}
+)
+
+const groupPadding = 11
+const levelPadding = 5
+
+func NewSlogHandler(writer io.Writer, options Options) *SlogHandler {
+	writerFile, writerIsFile := writer.(*os.File)
+	if writerIsFile {
+		options.IsTerminal = isatty.IsTerminal(writerFile.Fd())
+	}
+
+	return &SlogHandler{
+		options:	options,
+		attrs:		[]slog.Attr{},
+		group:		"OTHER",
+		mutex:		&sync.Mutex{},
+		writer:		writer,
+	}
+}
+
+func (log *SlogHandler) appendRecord(buf *strings.Builder, record slog.Record) {
+	log.appendTime(buf, record.Time)
+	log.appendGroup(buf, log.group)
+	log.appendLevel(buf, record.Level)
+	log.appendMessage(buf, record.Message)
+
+	for _, attr := range log.attrs {
+		log.appendAttr(buf, attr)
+	}
+
+	record.Attrs(func(attr slog.Attr) bool {
+		log.appendAttr(buf, attr)
+		return true
+	})
+}
+
+func (log *SlogHandler) appendTime(buf *strings.Builder, t time.Time) {
+	if !t.IsZero() {
+		if log.options.IsTerminal {
+			buf.WriteString(colour.Dim + colour.Gray)
+		}
+		buf.WriteRune('[')
+		buf.WriteString(t.Format(time.UnixDate))
+		buf.WriteRune(']')
+		if log.options.IsTerminal {
+			buf.WriteString(colour.Reset)
+		}
+		buf.WriteRune(' ')
+	}
+}
+
+func (log *SlogHandler) appendGroup(buf *strings.Builder, group string) {
+	if log.options.IsTerminal {
+		buf.WriteString(colour.Dim + colour.Gray)
+	}
+	log.appendPadLeft(buf, groupPadding, group)
+	if log.options.IsTerminal {
+		buf.WriteString(colour.Reset)
+	}
+	buf.WriteRune(' ')
+}
+
+func (log *SlogHandler) appendPadLeft(buf *strings.Builder, padding int, content string) {
+	padding -= len(content)
+	for i := padding; i > 0; i-- {
+		buf.WriteRune(' ')
+	}
+	buf.WriteString(content)
+}
+
+func (log *SlogHandler) appendPadRight(buf *strings.Builder, padding int, content string) {
+	buf.WriteString(content)
+	padding -= len(content)
+	for i := padding; i > 0; i-- {
+		buf.WriteRune(' ')
+	}
+}
+
+func (log *SlogHandler) appendLevel(buf *strings.Builder, level slog.Level) {
+	if log.options.IsTerminal {
+		levelColour := colour.Reset
+		switch level {
+		case slog.LevelDebug:
+			levelColour = colour.Purple
+		case slog.LevelError:
+			levelColour = colour.Red
+		case slog.LevelWarn:
+			levelColour = colour.Yellow
+		case slog.LevelInfo:
+			levelColour = colour.Cyan
+		}
+		buf.WriteString(levelColour)
+	}
+	log.appendPadRight(buf, levelPadding, level.String())
+	if log.options.IsTerminal {
+		buf.WriteString(colour.Reset)
+	}
+	buf.WriteRune(' ')
+}
+
+func (log *SlogHandler) appendMessage(buf *strings.Builder, message string) {
+	if message != "" {
+		buf.WriteString(message)
+		buf.WriteRune(' ')
+	}
+}
+
+func (log *SlogHandler) appendAttr(buf *strings.Builder, attr slog.Attr) {
+	buf.WriteString(attr.String())
+	buf.WriteRune(' ')
+}
+
+func (log *SlogHandler) Enabled(ctx context.Context, level slog.Level) bool {
+	return level >= log.options.Level.Level()
+}
+
+func (log *SlogHandler) Handle(ctx context.Context, record slog.Record) error {
+	buf := &strings.Builder{}
+
+	log.appendRecord(buf, record)
+
+	buf.WriteRune('\n')
+
+	log.mutex.Lock()
+	defer log.mutex.Unlock()
+
+	if _, err := log.writer.Write([]byte(buf.String())); err != nil {
+		return err
+	}
+
+	for _, handler := range log.options.Handlers {
+		if err := handler.Handle(ctx, record); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (log *SlogHandler) WithGroup(group string) slog.Handler {
+	log2 := *log
+	log2.group = group
+	log2.options.Handlers = make([]slog.Handler, len(log.options.Handlers))
+	for i, handler := range log.options.Handlers {
+		log.options.Handlers[i] = handler.WithGroup(group)
+	}
+	return &log2
+}
+
+func (log *SlogHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	log2 := *log
+	log2.attrs = make([]slog.Attr, 0, len(log.attrs)+len(attrs))
+	log2.attrs = append(log2.attrs, log.attrs...)
+	log2.attrs = append(log2.attrs, attrs...)
+	log2.options.Handlers = make([]slog.Handler, len(log.options.Handlers))
+	for i, handler := range log.options.Handlers {
+		log.options.Handlers[i] = handler.WithAttrs(attrs)
+	}
+	return &log2
+}