From b4933a6fd1fbc7f1024bcd6d42168a1ed5486643 Mon Sep 17 00:00:00 2001
From: Jerry Yan <792602257@qq.com>
Date: Tue, 28 Apr 2026 13:53:02 +0800
Subject: [PATCH] feat(logger): slog-based logger with JSON and text handlers

---
 internal/infra/logger/logger.go      | 63 ++++++++++++++++++++++++++++
 internal/infra/logger/logger_test.go | 59 ++++++++++++++++++++++++++
 2 files changed, 122 insertions(+)
 create mode 100644 internal/infra/logger/logger.go
 create mode 100644 internal/infra/logger/logger_test.go

diff --git a/internal/infra/logger/logger.go b/internal/infra/logger/logger.go
new file mode 100644
index 0000000..e0da03c
--- /dev/null
+++ b/internal/infra/logger/logger.go
@@ -0,0 +1,63 @@
+// Package logger 提供基于标准库 log/slog 的结构化日志器封装：
+// 统一的 Format / Level 选项，以及按环境区分默认值的 FromEnv 便利函数。
+package logger
+
+import (
+	"io"
+	"log/slog"
+	"os"
+)
+
+// Format 表示日志输出格式。
+type Format string
+
+// 支持的输出格式。
+const (
+	FormatJSON Format = "json"
+	FormatText Format = "text"
+)
+
+// Level 是 slog.Level 的类型别名，方便外部直接使用本包常量而无需引入 log/slog。
+type Level = slog.Level
+
+// 常用日志级别（与 slog 同名常量等价）。
+const (
+	LevelDebug = slog.LevelDebug
+	LevelInfo  = slog.LevelInfo
+	LevelWarn  = slog.LevelWarn
+	LevelError = slog.LevelError
+)
+
+// Options 控制日志器的输出格式、最低级别与目标 Writer。
+// Writer 留空时默认写入 os.Stdout。
+type Options struct {
+	Format Format
+	Level  Level
+	Writer io.Writer
+}
+
+// New 按 Options 构造一个 *slog.Logger。Format 非 FormatText 时一律使用 JSON handler。
+func New(opt Options) *slog.Logger {
+	w := opt.Writer
+	if w == nil {
+		w = os.Stdout
+	}
+	hopts := &slog.HandlerOptions{Level: opt.Level, AddSource: false}
+	var h slog.Handler
+	switch opt.Format {
+	case FormatText:
+		h = slog.NewTextHandler(w, hopts)
+	default:
+		h = slog.NewJSONHandler(w, hopts)
+	}
+	return slog.New(h)
+}
+
+// FromEnv 根据环境名返回合适默认：
+// development → text + debug；其他 → json + info。
+func FromEnv(env string, w io.Writer) *slog.Logger {
+	if env == "development" {
+		return New(Options{Format: FormatText, Level: LevelDebug, Writer: w})
+	}
+	return New(Options{Format: FormatJSON, Level: LevelInfo, Writer: w})
+}
diff --git a/internal/infra/logger/logger_test.go b/internal/infra/logger/logger_test.go
new file mode 100644
index 0000000..8b46553
--- /dev/null
+++ b/internal/infra/logger/logger_test.go
@@ -0,0 +1,59 @@
+package logger
+
+import (
+	"bytes"
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestNew_JSONHandler_WritesStructured(t *testing.T) {
+	var buf bytes.Buffer
+	log := New(Options{Format: FormatJSON, Level: LevelInfo, Writer: &buf})
+	log.Info("hello", "key", "value")
+
+	var got map[string]any
+	require.NoError(t, json.Unmarshal(buf.Bytes(), &got))
+	require.Equal(t, "hello", got["msg"])
+	require.Equal(t, "value", got["key"])
+	require.Equal(t, "INFO", got["level"])
+}
+
+func TestNew_TextHandler_HumanReadable(t *testing.T) {
+	var buf bytes.Buffer
+	log := New(Options{Format: FormatText, Level: LevelDebug, Writer: &buf})
+	log.Debug("dev message", "x", 1)
+	require.Contains(t, buf.String(), "dev message")
+}
+
+func TestNew_LevelFilter(t *testing.T) {
+	var buf bytes.Buffer
+	log := New(Options{Format: FormatJSON, Level: LevelWarn, Writer: &buf})
+	log.Info("should be filtered")
+	require.Empty(t, strings.TrimSpace(buf.String()))
+}
+
+func TestFromEnv_DevelopmentUsesText(t *testing.T) {
+	var buf bytes.Buffer
+	log := FromEnv("development", &buf)
+	log.Debug("dev", "k", "v")
+	out := buf.String()
+	require.Contains(t, out, "dev")
+	// text handler outputs key=value pairs (not JSON braces)
+	require.NotContains(t, out, `"msg":`)
+}
+
+func TestFromEnv_NonDevelopmentUsesJSON(t *testing.T) {
+	var buf bytes.Buffer
+	log := FromEnv("production", &buf)
+	// Debug should be filtered (JSON default level is Info)
+	log.Debug("filtered")
+	require.Empty(t, strings.TrimSpace(buf.String()))
+
+	log.Info("prod")
+	var got map[string]any
+	require.NoError(t, json.Unmarshal(buf.Bytes(), &got))
+	require.Equal(t, "prod", got["msg"])
+}