package main

import (
	"me-fit/handler"
	"me-fit/types"
	"me-fit/utils"
	"os"

	"context"
	"database/sql"
	"log"
	"log/slog"
	"net/http"
	"os/signal"
	"sync"
	"syscall"
	"time"

	"github.com/joho/godotenv"
	_ "github.com/mattn/go-sqlite3"
	"github.com/prometheus/client_golang/prometheus/promhttp"
)

func main() {
	err := godotenv.Load()
	if err != nil {
		log.Fatal("Error loading .env file")
	}

	db, err := sql.Open("sqlite3", "./data.db")
	if err != nil {
		log.Fatal("Could not open Database data.db: ", err)
	}
	defer db.Close()

	run(context.Background(), db, os.Getenv)
}

func run(ctx context.Context, db *sql.DB, env func(string) string) {
	ctx, cancel := signal.NotifyContext(ctx, syscall.SIGINT, syscall.SIGTERM)
	defer cancel()

	slog.Info("Starting server...")

	// init server settings
	serverSettings := types.NewServerSettingsFromEnv(env)

	// init db
	err := utils.RunMigrations(db, "")
	if err != nil {
		slog.Error("Could not run migrations: " + err.Error())
		os.Exit(1)
	}

	// init servers
	var prometheusServer *http.Server
	if serverSettings.PrometheusEnabled {
		prometheusServer := &http.Server{
			Addr:    ":8081",
			Handler: promhttp.Handler(),
		}
		go startServer(prometheusServer)
	}

	httpServer := &http.Server{
		Addr:    ":" + serverSettings.Port,
		Handler: handler.GetHandler(db, serverSettings),
	}
	go startServer(httpServer)

	// graceful shutdown
	var wg sync.WaitGroup
	wg.Add(2)
	go shutdownServer(httpServer, ctx, &wg)
	go shutdownServer(prometheusServer, ctx, &wg)
	wg.Wait()
}

func startServer(s *http.Server) {
	slog.Info("Starting server on " + s.Addr)
	if err := s.ListenAndServe(); err != nil && err != http.ErrServerClosed {
		slog.Error("error listening and serving: " + err.Error())
	}
}

func shutdownServer(s *http.Server, ctx context.Context, wg *sync.WaitGroup) {
	defer wg.Done()
	if s == nil {
		return
	}

	<-ctx.Done()
	shutdownCtx := context.Background()
	shutdownCtx, cancel := context.WithTimeout(shutdownCtx, 10*time.Second)
	defer cancel()
	if err := s.Shutdown(shutdownCtx); err != nil {
		slog.Error("error shutting down http server: " + err.Error())
	} else {
		slog.Info("Gracefully stopped http server on " + s.Addr)
	}
}