// 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"
	"os"
	"path/filepath"

	"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 {
	var log *logger.Logger
	if cfg.App.Env == "dev" {
		log = logger.NewDevelopment()
	} else {
		log = logger.New(cfg.Logger.Level).Expect("create logger") // might fail dramatically
	}
	return &app{
		cfg:     cfg,
		log:     log,
		greeter: greeter.New(log),
	}
}

func main() {
	conf := parseArgs()

	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() {
	// High level business logic goes here
	a.showGreeting(a.cfg.Greeter.Name)

	// Human readable messages.
	// Use logs for presenting technical data in machine friendly format.
	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)
}