feat(backend): module scaffold, config, gin router with healthz

backend/internal/api/router.go

@@ -0,0 +1,24 @@
+package api
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+
+	"booklib/internal/config"
+)
+
+type api struct {
+	cfg *config.Config
+	// st, rdb, sc 字段在 Task 4/9 加入
+}
+
+func NewRouter(cfg *config.Config) *gin.Engine {
+	gin.SetMode(gin.ReleaseMode)
+	_ = &api{cfg: cfg} // Task 4/9 起此处为 a := &api{...}，handler 挂在 a 上
+	r := gin.New()
+	r.Use(gin.Recovery())
+	g := r.Group("/api")
+	g.GET("/healthz", func(c *gin.Context) { c.String(http.StatusOK, "ok") })
+	return r
+}

backend/internal/api/router_test.go

@@ -0,0 +1,24 @@
+package api
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"booklib/internal/config"
+)
+
+func testCfg() *config.Config {
+	return &config.Config{Addr: ":8080", JWTSecret: []byte("s3cret"), ScanInterval: time.Minute, UploadMaxMB: 200}
+}
+
+func TestHealthz(t *testing.T) {
+	r := NewRouter(testCfg())
+	req := httptest.NewRequest(http.MethodGet, "/api/healthz", nil)
+	w := httptest.NewRecorder()
+	r.ServeHTTP(w, req)
+	if w.Code != http.StatusOK {
+		t.Fatalf("healthz = %d, want 200", w.Code)
+	}
+}

backend/internal/config/config.go

@@ -0,0 +1,54 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"time"
+)
+
+type Config struct {
+	Addr          string
+	DatabaseURL   string
+	RedisURL      string
+	JWTSecret     []byte
+	AdminUser     string
+	AdminPassword string
+	BooksDir      string
+	CacheDir      string
+	ScanInterval  time.Duration
+	UploadMaxMB   int64
+}
+
+func Load() (*Config, error) {
+	env := func(k, def string) string {
+		if v := os.Getenv(k); v != "" {
+			return v
+		}
+		return def
+	}
+	scanSec, err := strconv.Atoi(env("SCAN_INTERVAL_SEC", "60"))
+	if err != nil {
+		return nil, fmt.Errorf("SCAN_INTERVAL_SEC: %w", err)
+	}
+	uploadMB, err := strconv.ParseInt(env("UPLOAD_MAX_MB", "200"), 10, 64)
+	if err != nil {
+		return nil, fmt.Errorf("UPLOAD_MAX_MB: %w", err)
+	}
+	secret := os.Getenv("JWT_SECRET")
+	if secret == "" {
+		return nil, fmt.Errorf("JWT_SECRET required")
+	}
+	return &Config{
+		Addr:          env("ADDR", ":8080"),
+		DatabaseURL:   env("DATABASE_URL", ""),
+		RedisURL:      env("REDIS_URL", ""),
+		JWTSecret:     []byte(secret),
+		AdminUser:     env("ADMIN_USER", ""),
+		AdminPassword: env("ADMIN_PASSWORD", ""),
+		BooksDir:      env("BOOKS_DIR", "/data/books"),
+		CacheDir:      env("CACHE_DIR", "/data/cache"),
+		ScanInterval:  time.Duration(scanSec) * time.Second,
+		UploadMaxMB:   uploadMB,
+	}, nil
+}