Initial commit

internal/api/api.go

@@ -0,0 +1,177 @@
+package api
+
+import (
+	"context"
+	"database/sql"
+	"expvar"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"os"
+	"runtime"
+	"sync"
+	"time"
+
+	"gardomatic.kleiax.de/internal/mailer"
+	"gardomatic.kleiax.de/internal/storage"
+	"gardomatic.kleiax.de/internal/storage/postgres"
+	"gardomatic.kleiax.de/internal/vcs"
+
+	"github.com/alexedwards/scs/postgresstore"
+	"github.com/alexedwards/scs/v2"
+	_ "github.com/lib/pq"
+)
+
+var (
+	version = vcs.Version()
+)
+
+// Config contains API server, database, session, mail, and security settings.
+type Config struct {
+	Host       string
+	Port       int
+	Env        string
+	WebBaseURL string
+	DB         DatabaseConfig
+	Limiter    LimiterConfig
+	Session    SessionConfig
+	Mail       mailer.Config
+	Cors       CORSConfig
+}
+
+// DatabaseConfig controls the PostgreSQL connection pool.
+type DatabaseConfig struct {
+	Dsn          string
+	MaxOpenConns int
+	MaxIdleConns int
+	MaxIdleTime  time.Duration
+}
+
+// LimiterConfig controls per-client HTTP rate limiting.
+type LimiterConfig struct {
+	Enabled bool
+	Rps     float64
+	Burst   int
+}
+
+// SessionConfig controls the session cookie and server-side session lifetime.
+type SessionConfig struct {
+	Lifetime     time.Duration
+	IdleTimeout  time.Duration
+	CookieName   string
+	CookieSecure bool
+}
+
+// CORSConfig lists origins allowed to make cross-origin API requests.
+type CORSConfig struct {
+	TrustedOrigins []string
+}
+
+type application struct {
+	config   Config
+	logger   *slog.Logger
+	models   storage.Models
+	mailer   *mailer.Mailer
+	sessions *scs.SessionManager
+	wg       sync.WaitGroup
+	// db is retained by the application so Run can close the connection pool.
+	db *sql.DB
+}
+
+// New initializes the API application and its database-backed dependencies.
+func New(cfg Config) *application {
+	var handler slog.Handler = slog.NewTextHandler(os.Stdout, nil)
+	if cfg.Env == "production" {
+		handler = slog.NewJSONHandler(os.Stdout, nil)
+	}
+	logger := slog.New(handler)
+
+	db, err := openDB(cfg)
+	if err != nil {
+		logger.Error(err.Error())
+		os.Exit(1)
+	}
+
+	logger.Info("database connection pool established")
+
+	expvar.NewString("version").Set(version)
+
+	expvar.Publish("goroutines", expvar.Func(func() any {
+		return runtime.NumGoroutine()
+	}))
+
+	expvar.Publish("database", expvar.Func(func() any {
+		return db.Stats()
+	}))
+
+	expvar.Publish("timestamp", expvar.Func(func() any {
+		return time.Now().Unix()
+	}))
+
+	mailer, err := mailer.New(cfg.Mail)
+	if err != nil {
+		logger.Error(err.Error())
+		os.Exit(1)
+	}
+
+	sessions := scs.New()
+	sessions.Store = postgresstore.New(db)
+	sessions.Lifetime = cfg.Session.Lifetime
+	sessions.IdleTimeout = cfg.Session.IdleTimeout
+	sessions.HashTokenInStore = true
+	sessions.Cookie.Name = cfg.Session.CookieName
+	sessions.Cookie.HttpOnly = true
+	sessions.Cookie.SameSite = http.SameSiteLaxMode
+	sessions.Cookie.Secure = cfg.Session.CookieSecure
+
+	app := &application{
+		config:   cfg,
+		logger:   logger,
+		models:   postgres.New(db),
+		mailer:   mailer,
+		sessions: sessions,
+		db:       db,
+	}
+
+	sessions.ErrorFunc = app.serverErrorResponse
+
+	return app
+}
+
+// Run serves API requests until shutdown and then releases application resources.
+func (app *application) Run() {
+	defer app.db.Close()
+
+	err := app.serve()
+	if err != nil {
+		app.logger.Error(err.Error())
+		os.Exit(1)
+	}
+}
+
+// Version returns the version embedded in the API binary.
+func (app *application) Version() string {
+	return fmt.Sprintf("Version:\t%s\n", version)
+}
+
+func openDB(cfg Config) (*sql.DB, error) {
+	db, err := sql.Open("postgres", cfg.DB.Dsn)
+	if err != nil {
+		return nil, err
+	}
+
+	db.SetMaxOpenConns(cfg.DB.MaxOpenConns)
+	db.SetMaxIdleConns(cfg.DB.MaxIdleConns)
+	db.SetConnMaxIdleTime(cfg.DB.MaxIdleTime)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	err = db.PingContext(ctx)
+	if err != nil {
+		db.Close()
+		return nil, err
+	}
+
+	return db, nil
+}