// Dialectic.Backend.Go — entrypoint.
//
// Greenfield Go rewrite of the Python v1 backend; agent-only debate
// platform per /home/hzhang/arch/DIALECTIC-V2-DESIGN.md.
//
// This file: load config → open db → run migrations → mount routes →
// serve until SIGINT/SIGTERM. Everything else lives in internal/.
package main

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

	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/config"
	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/db"
	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/httpapi"
	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/orchestrator"
	"git.hangman-lab.top/hzhang/Dialectic.Backend/internal/store"
)

// Version is overridden at build time via -ldflags="-X main.Version=...".
var Version = "dev"

func main() {
	log.SetFlags(log.LstdFlags | log.Lmicroseconds | log.Lshortfile)

	cfg, err := config.LoadFromEnv()
	if err != nil {
		log.Fatalf("config: %v", err)
	}
	log.Printf("starting dialectic-backend %s mode=%s addr=%s", Version, cfg.Mode, cfg.HTTPAddr)

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	conn, err := db.Open(ctx, cfg.DSN())
	if err != nil {
		log.Fatalf("db open: %v", err)
	}
	defer conn.Close()

	if err := db.RunMigrations(ctx, conn); err != nil {
		log.Fatalf("migrations: %v", err)
	}
	log.Printf("migrations: ok")

	// Wire orchestrator + start the ticker. Backend no longer broadcasts
	// to Fabric — proposers post a single recruitment fabric-send-message,
	// downstream agents book HF on_call slots to be woken at debate time.
	topicStore := store.NewTopicStore(conn)
	signupStore := store.NewSignupStore(conn)
	campStore := store.NewCampStore(conn)
	roundStore := store.NewRoundStore(conn)
	ticker := orchestrator.NewTicker(conn, topicStore, signupStore, campStore, roundStore,
		cfg.OrchestratorTickInterval)
	go ticker.Run(ctx)

	srv := &http.Server{
		Addr:              cfg.HTTPAddr,
		Handler:           httpapi.Mount(cfg, conn, Version),
		ReadHeaderTimeout: 10 * time.Second,
	}

	// Graceful shutdown on SIGINT/SIGTERM.
	shutdown := make(chan os.Signal, 1)
	signal.Notify(shutdown, os.Interrupt, syscall.SIGTERM)
	go func() {
		<-shutdown
		log.Printf("shutdown signal received")
		ctx2, cancel := context.WithTimeout(context.Background(), 10*time.Second)
		defer cancel()
		if err := srv.Shutdown(ctx2); err != nil {
			log.Printf("http shutdown error: %v", err)
		}
	}()

	log.Printf("http server listening on %s", cfg.HTTPAddr)
	if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
		log.Fatalf("http serve: %v", err)
	}
	log.Printf("bye")
}