package main

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

	"github.com/allai/allai-backend/internal/app"
	"github.com/allai/allai-backend/internal/config"
	"github.com/allai/allai-backend/internal/httpapi"
	"github.com/allai/allai-backend/internal/provider/mock"
)

func main() {
	cfg := config.Load()

	logger := log.New(os.Stdout, "[allai-backend] ", log.LstdFlags|log.Lmsgprefix)

	var provider app.GenerationProvider
	switch cfg.ProviderKind {
	case "mock":
		provider = mock.New()
	default:
		logger.Printf("provider %q not recognised, falling back to mock provider", cfg.ProviderKind)
		provider = mock.New()
	}

	service := app.NewService(provider)
	router := httpapi.NewRouter(service, logger)

	server := &http.Server{
		Addr:         cfg.Address(),
		Handler:      router,
		ReadTimeout:  15 * time.Second,
		WriteTimeout: 60 * time.Second,
		IdleTimeout:  90 * time.Second,
	}

	go func() {
		logger.Printf("server starting on %s", cfg.Address())
		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			logger.Fatalf("http server failed: %v", err)
		}
	}()

	shutdown(server, logger)
}

func shutdown(server *http.Server, logger *log.Logger) {
	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	<-ctx.Done()
	logger.Println("shutdown signal received, draining requests…")

	shutdownCtx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
	defer cancel()

	if err := server.Shutdown(shutdownCtx); err != nil {
		logger.Printf("graceful shutdown failed: %v", err)
		if closeErr := server.Close(); closeErr != nil {
			logger.Printf("forced close failed: %v", closeErr)
		}
	}

	logger.Println("server stopped cleanly")
}