pulley/cmd/api/main.go

package main

import (
	"context"
	"database/sql"
	"errors"

	// "flag"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"git.runcible.io/learning/pulley/internal/config"
	"git.runcible.io/learning/pulley/internal/database"
	"git.runcible.io/learning/pulley/internal/logging"
	"git.runcible.io/learning/pulley/migrations"
)

const Version = "1.0.0"

//type config struct {
//	port     int
//	env      string
//	logLevel string
//}

type application struct {
	config config.ServiceConfig
	logger *slog.Logger
}

func run(ctx context.Context, w io.Writer, args []string) error {
	//	var cfg config

	//	flagSet := flag.NewFlagSet(args[0], flag.ExitOnError)

	//	flagSet.IntVar(&cfg.port, "port", 5002, "API server port")
	//	flagSet.StringVar(&cfg.env, "env", "development", "Environment (development|staging|production)")
	//	flagSet.StringVar(&cfg.logLevel, "log-level", "INFO", "Logging Level (INFO|DEBUG|WARN|ERROR)")

	//	if err := flagSet.Parse(args[1:]); err != nil {
	//		return err
	//	}

	cfg := config.GetServiceConfig()

	logger := logging.InitLogging(cfg.LogLevel, w, true)

	signalCtx, stop := signal.NotifyContext(ctx, syscall.SIGTERM, syscall.SIGINT)
	defer func() {
		slog.Info("Calling signal watcher stop.")
		stop()
	}()

	// appCtx is a context that can be programatically called to initiate the shutdown process
	// it inherits from signalCtx which will stop on receipt of an OS signal. You can think of
	// appCtx as responding to internal signals in the app, and signalCtx as responding to
	// external signals sent to the app.
	appCtx, cancel := context.WithCancel(signalCtx)
	defer cancel()

	//run migrations
	db, err := sql.Open("pgx", cfg.DatabaseUri)
	if err != nil {
		logger.Error("Error opening migrations connection")
		return err
	}
	defer db.Close()

	err = migrations.Migrate(db)
	if err != nil {
		logger.Error("Error in migrations", "error", err.Error())
		return err
	}

	logger.Info("Migrations applied.")
	db.Close()

	pool, err := database.OpenPgPool(ctx, cfg)
	if err != nil {
		return err
	}
	defer func() {
		slog.Info("Closing database connection pool")
		pool.Close()
	}()

	app := application{config: cfg, logger: logger}

	srv := &http.Server{
		Addr:           fmt.Sprintf("%s:%d", "0.0.0.0", app.config.Port),
		ErrorLog:       slog.NewLogLogger(app.logger.Handler(), slog.LevelError),
		IdleTimeout:    time.Minute,
		ReadTimeout:    5 * time.Second,
		WriteTimeout:   10 * time.Second,
		MaxHeaderBytes: 524288, // 0.5 mb
		Handler:        app.routes(),
	}

	slog.Info(fmt.Sprintf("Listening on http://%s", srv.Addr))

	defer func() {
		slog.Debug("Must have hit a graceful shutdown")
	}()

	go func() {
		if err := srv.ListenAndServe(); !errors.Is(err, http.ErrServerClosed) {
			slog.Error("Error encounterd by webserver in listen loop", "error", err.Error())
			cancel()
		}
	}()

	// Handle graceful shutdown

	// This was an older way to do it before 1.16. Now we can use signal.NotifyContext
	// sigChan := make(chan os.Signal, 1)
	// signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
	// Block until signal is received
	//<-sigChan
	slog.Info("Listening for shutdown...")
	<-appCtx.Done()

	slog.Info("Shutdown intitiated")

	// We don't want to inherit from appCtx because it has already been canceled at this point
	shutdownCtx, shutdownRelease := context.WithTimeout(context.Background(), 10*time.Second)
	defer shutdownRelease()

	if err := srv.Shutdown(shutdownCtx); err != nil {
		slog.Error("Failed to close within context timeout. Forcing server close.")
		srv.Close()
		return err
	}
	return nil

}

func main() {
	ctx := context.Background()
	if err := run(ctx, os.Stdout, os.Args); err != nil {
		slog.Error(err.Error())
		os.Exit(1)
	}

}