inventory-plus-plus/main.go

package main

//go:generate planter postgres://planter:planter@localhost:5432/inventory_2?sslmode=disable -o diagrams/database_schema.uml
//go:generate plantuml diagrams/*.uml -tsvg
//go:generate plantuml diagrams/etsy/*.uml -tsvg
//go:generate npx @tailwindcss/cli -i styles/source.css -o styles/index.css --cwd ./internal/server

import (
	"context"
	"errors"
	"fmt"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/jackc/pgx/v5/pgxpool"

	"ruben/inventory2/internal/domains/accounts"
	"ruben/inventory2/internal/domains/authentication"
	etsy_platform "ruben/inventory2/internal/domains/platforms/etsy"
	"ruben/inventory2/internal/domains/raw_events"
	"ruben/inventory2/internal/server"
)

const (
	etsyAPIKeystring    = "38ncokqh0jih5jshfk8iv4n5"
	etsyAPISharedSecret = "jaaw0tyizf"
)

func main() {
	if err := runApp(context.Background()); err != nil {
		panic(err)
	}
	fmt.Println("application shutdown")
}

func runApp(ctx context.Context) error {
	ctx, shutdown := context.WithCancel(ctx)
	defer shutdown()

	logger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
		AddSource: true,
		Level:     slog.LevelDebug,
		ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
			fmt.Println("slog groups:", groups)
			fmt.Println("slog attr:", a)
			// TODO: not sure if this will be needed, but keep around until known.
			return a
		},
	}))

	// connect to the database

	connPool, err := newPool(ctx)
	if err != nil {
		return fmt.Errorf("failed to initialize database connection pool: %w", err)
	}

	// start background processes

	auth, err := authentication.New(ctx, connPool, logger.WithGroup("*authentication.Authenticator"))
	if err != nil {
		return fmt.Errorf("failed to construct authenticator: %w", err)
	}

	authErrCh := runAuthProcesses(ctx, auth)

	// start http server

	srvErrCh := runServer(ctx, logger, connPool, auth)

	// wait for interrupt signal or unrecoverable failure, then shutdown

	osSignalCh := make(chan os.Signal, 1)
	signal.Notify(osSignalCh, syscall.SIGINT, syscall.SIGTERM)

	var (
		alreadyShutdown struct {
			server        bool
			authProcesses bool
		}
	)
	select {
	case s := <-osSignalCh:
		fmt.Println("application received shutdown signal:", s)
		fmt.Println("shutting down")
	case err := <-authErrCh:
		alreadyShutdown.authProcesses = true
		fmt.Println("auth processes shutdown unexpectedly")
		if err != nil {
			fmt.Println("auth processes encountered error:", err)
		}
	case err := <-srvErrCh:
		alreadyShutdown.server = true
		fmt.Println("server shutdown unexpectedly")
		if err != nil {
			fmt.Println("server encountered error:", err)
		}
	}

	shutdown()

	// capture application errors that occurred during or caused shutdown

	var errs []error

	if !alreadyShutdown.authProcesses {
		if err := <-authErrCh; err != nil {
			errs = append(errs, fmt.Errorf("auth processes experienced an error: %w", err))
		}
		fmt.Println("auth processes shut down")
	}

	if !alreadyShutdown.server {
		if err := <-srvErrCh; err != nil {
			errs = append(errs, fmt.Errorf("server experienced an error: %w", err))
		}
		fmt.Println("server shut down")
	}

	return errors.Join(errs...)
}

func runAuthProcesses(ctx context.Context, auth *authentication.Authenticator) <-chan error {
	errCh := make(chan error, 1)
	go func() {
		defer close(errCh)

		if err := auth.RunBackgroundCleanup(ctx); err != nil {
			errCh <- err
		}
	}()

	return errCh
}

func runServer(ctx context.Context, logger *slog.Logger, connPool *pgxpool.Pool, auth *authentication.Authenticator) <-chan error {
	srv := &http.Server{
		Addr: ":8082", // local
		Handler: server.NewServer(
			logger.WithGroup("server"),
			"./",
			raw_events.NewStore(logger.WithGroup("raw-event-store"), connPool),
			accounts.NewStore(logger, connPool),
			etsy_platform.NewPlatform(
				logger,
				func(acctID int64) string {
					return fmt.Sprintf("/oauth/account/%d/auth_code", acctID)
				},
				etsyAPIKeystring,
				etsyAPISharedSecret,
				connPool,
			),
			auth,
		),
	}

	ctx, cancel := context.WithCancel(ctx)
	alreadyShutdownCh := make(chan struct{}, 1)

	runningErrCh := make(chan error, 1)
	go func() {
		defer close(runningErrCh)
		defer cancel()
		defer close(alreadyShutdownCh)

		fmt.Println("server running on 8082...")
		if err := srv.ListenAndServe(); err != nil {
			if !errors.Is(err, http.ErrServerClosed) {
				runningErrCh <- fmt.Errorf("server experienced error: %w", err)
			}
		}
	}()

	shutdownErrCh := make(chan error, 1)
	go func() {
		defer close(shutdownErrCh)

		select {
		case <-alreadyShutdownCh:
			return
		case <-ctx.Done():
		}

		shutdownCtx, cancelShutdown := context.WithTimeout(context.Background(), 60*time.Second)
		defer cancelShutdown()
		if err := srv.Shutdown(shutdownCtx); err != nil {
			shutdownErrCh <- fmt.Errorf("error occurred attempting to shutdown server: %w", err)
		}
	}()

	errCh := make(chan error, 1)
	go func() {
		defer close(errCh)

		err1 := <-runningErrCh
		err2 := <-shutdownErrCh
		if err := errors.Join(err1, err2); err != nil {
			errCh <- err
		}
	}()

	return errCh
}