fix: add hclog2slog module

pkg/hclog2slog/hclog2slog.go

@@ -0,0 +1,123 @@
+// Package hclog2slog provides an adapter that wraps a HashiCorp hclog.Logger
+// and exposes it as a Go slog.Logger.
+//
+// This allows you to integrate libraries that use the modern slog API
+// with systems or dependencies that still rely on HashiCorp's hclog.
+
+// The adapter maps slog levels to hclog levels and preserves key/value fields.
+package hclog2slog
+
+import (
+	"context"
+	"log/slog"
+
+	"github.com/hashicorp/go-hclog"
+)
+
+// levelMapToHclog converts slog.Level to hclog.Level.
+var levelMapToHclog = map[slog.Level]hclog.Level{
+	slog.LevelDebug - 4: hclog.Trace,
+	slog.LevelDebug:     hclog.Debug,
+	slog.LevelInfo:      hclog.Info,
+	slog.LevelWarn:      hclog.Warn,
+	slog.LevelError:     hclog.Error,
+	slog.LevelError + 4: hclog.Off,
+}
+
+// levelMapFromHclog converts hclog.Level to slog.Level.
+var levelMapFromHclog = map[hclog.Level]slog.Level{
+	hclog.Trace: slog.LevelDebug - 4,
+	hclog.Debug: slog.LevelDebug,
+	hclog.Info:  slog.LevelInfo,
+	hclog.Warn:  slog.LevelWarn,
+	hclog.Error: slog.LevelError,
+	hclog.Off:   slog.LevelError + 4,
+}
+
+// hclogHandler implements slog.Handler by delegating to an hclog.Logger.
+type hclogHandler struct {
+	hcl  hclog.Logger
+	lvl  slog.Level
+	args []any
+}
+
+// New creates a new slog.Logger backed by an hclog.Logger.
+//
+// The returned *slog.Logger will send all log events to the given hclog.Logger
+// with compatible levels and fields.
+func New(hclLogger hclog.Logger) *slog.Logger {
+	return NewWithLevel(hclLogger, hclLogger.GetLevel())
+}
+
+func NewWithStringLevel(hclLogger hclog.Logger, logLevel string) *slog.Logger {
+	return NewWithLevel(hclLogger, hclog.LevelFromString(logLevel))
+}
+
+func NewWithLevel(hclLogger hclog.Logger, logLevel hclog.Level) *slog.Logger {
+	handler := &hclogHandler{
+		hcl: hclLogger,
+		lvl: levelMapFromHclog[logLevel],
+	}
+	return slog.New(handler)
+}
+
+// Enabled checks whether the given level is enabled on the underlying hclog.Logger.
+func (h *hclogHandler) Enabled(_ context.Context, level slog.Level) bool {
+	hclLevel := levelMapToHclog[level]
+	switch hclLevel {
+	case hclog.Trace:
+		return h.hcl.IsTrace()
+	case hclog.Debug:
+		return h.hcl.IsDebug()
+	case hclog.Info:
+		return h.hcl.IsInfo()
+	case hclog.Warn:
+		return h.hcl.IsWarn()
+	case hclog.Error:
+		return h.hcl.IsError()
+	default:
+		return true
+	}
+}
+
+// Handle forwards the slog.Record to the underlying hclog.Logger.
+func (h *hclogHandler) Handle(_ context.Context, r slog.Record) error {
+	var kv []any
+
+	r.Attrs(func(a slog.Attr) bool {
+		kv = append(kv, a.Key, a.Value.Any())
+		return true
+	})
+
+	// Include any pre-bound args
+	if len(h.args) > 0 {
+		kv = append(kv, h.args...)
+	}
+
+	hclLevel := levelMapToHclog[r.Level]
+	h.hcl.Log(hclLevel, r.Message, kv...)
+
+	return nil
+}
+
+// WithAttrs creates a new handler with additional attributes.
+func (h *hclogHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	args := make([]any, 0, len(attrs)*2)
+	for _, a := range attrs {
+		args = append(args, a.Key, a.Value.Any())
+	}
+	return &hclogHandler{
+		hcl:  h.hcl,
+		lvl:  h.lvl,
+		args: append(h.args, args...),
+	}
+}
+
+// WithGroup creates a new handler that represents a logical sub-logger.
+func (h *hclogHandler) WithGroup(name string) slog.Handler {
+	return &hclogHandler{
+		hcl:  h.hcl.Named(name),
+		lvl:  h.lvl,
+		args: h.args,
+	}
+}