// main is the composition root for the application.
// It parses config, wires dependencies into an app struct, and delegates.
// Implementation details lives in internal/; cmd/ should be kept thin by
// deliberately operating only with high level concepts.
package main

import (
	"fmt"
	"io"
	"os"
	"path/filepath"

	"gitea.djmil.dev/go/template/internal/buildinfo"
	"gitea.djmil.dev/go/template/internal/greeter"
	"gitea.djmil.dev/go/template/pkg/logger"
	"gitea.djmil.dev/go/template/pkg/result"
)

// app holds all wired dependencies for the lifetime of the process.
type app struct {
	cfg     *Config
	log     *logger.Logger
	greeter *greeter.Service
}

func newApp(cfg *Config) *app {
	// Open the debug writer if requested. The OS closes it on exit.
	var debugOut io.Writer
	if cfg.Logger.LogDump != "" {
		debugOut = result.Of(os.Create(cfg.Logger.LogDump)).Expect("enable logs dump") // #nosec G304 — CLI flag
	}

	log := logger.NewCLI(cfg.Logger.Level, debugOut).Expect("create logger")
	log.Debug("config", "port", cfg.App.Port, "level", cfg.Logger.Level, "env", cfg.App.Env)
	if cfg.App.Env == "dev" {
		log.Warn("dev mode — not for production")
	}
	return &app{
		cfg:     cfg,
		log:     log,
		greeter: greeter.New(log),
	}
}

func main() {
	conf := parseArgs()

	if conf.Version {
		fmt.Println(buildinfo.String())
		return
	}

	app := newApp(conf)
	app.log.WithFields(map[string]any{
		"app": filepath.Base(os.Args[0]),
		"env": conf.App.Env,
	}).Info("starting up")

	if err := result.Run(app.run); err != nil {
		fmt.Fprintf(os.Stderr, "[failed] %v\n", err)
		if stack := result.StackTrace(err); stack != "" {
			fmt.Fprintf(os.Stderr, "%s\n", stack)
		}
		os.Exit(1)
	}
}

func (a *app) run() {
	// Warm up the greeter with a few names before the real call.
	// In debug mode this produces repeated identical debug lines from the greeter,
	// demonstrating how the deduplication counter collapses them in-place.
	for _, name := range []string{"Alice", "Bob", "Carol", "Dave"} {
		a.greeter.Greet(name)
	}

	a.showGreeting(a.cfg.Greeter.Name)

	fmt.Printf("TODO: implement listening on port %d\n", a.cfg.App.Port)
}

func (a *app) showGreeting(name string) {
	msg := a.greeter.Greet(name).Expect("greeting")
	a.log.WithField("message", msg).Info("greeting complete")
	fmt.Println(msg)
}