// Command telegramd is the long-polling bot loop for
// broad-announce M3 (SPEC §8). It pulls the list of
// active telegram_bots from Postgres, then for each bot
// long-polls getUpdates, parses commands, applies them
// via internal/telegram.Handler, and replies via
// SendMessage.
//
// M3 ships long-polling only. Webhook mode is M5/M9.
//
// Configuration:
//   BA_TELEGRAM_BOT_TOKEN        — fallback if DB has no row
//   BA_TELEGRAM_BASE_URL         — override for tests (default
//                                  https://api.telegram.org).
//                                  M3 dev: point at faketgmd.
//
// One process polls all bots. With M3's one-bot-per-company
// this is a single update loop; M3+ can shard by company
// hash if the volume warrants.
package main

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

	"git3.techno-world.net/lrosales/broad-announce/internal/broker"
	"git3.techno-world.net/lrosales/broad-announce/internal/config"
	"git3.techno-world.net/lrosales/broad-announce/internal/httpserver"
	"git3.techno-world.net/lrosales/broad-announce/internal/observability"
	"git3.techno-world.net/lrosales/broad-announce/internal/postgres"
	"git3.techno-world.net/lrosales/broad-announce/internal/telegram"
)

type botConfig struct {
	BotID     string
	CompanyID string
	BotToken  string
}

func main() {
	cfg, err := config.LoadCommon("telegramd")
	if err != nil {
		os.Stderr.WriteString("config: " + err.Error() + "\n")
		os.Exit(1)
	}
	logger := observability.Init(cfg.Env, cfg.LogLevel, "telegramd")
	logger.Info("starting", "env", cfg.Env, "addr", cfg.HTTPAddr)

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()

	br, err := broker.Connect(ctx, cfg.NATSURL)
	if err != nil {
		logger.Error("nats connect", "err", err)
		os.Exit(1)
	}
	defer br.Close()
	_ = br // M3: long-polling only; NATS used later for ack fan-out

	pool, err := postgres.Connect(ctx, cfg.PostgresDSN)
	if err != nil {
		logger.Error("postgres connect", "err", err)
		os.Exit(1)
	}
	defer pool.Close()

	baseURL := os.Getenv("BA_TELEGRAM_FAKE_URL")
	if baseURL == "" {
		baseURL = os.Getenv("BA_TELEGRAM_BASE_URL")
	}
	if baseURL == "" {
		baseURL = "http://faketgmd:8830" // M3 docker-compose default
	}
	logger.Info("telegram target", "base_url", baseURL)

	client := &telegram.HTTPBotClient{
		BaseURL: baseURL,
		HTTP:    &http.Client{Timeout: 60 * time.Second},
	}
	handler := telegram.NewHandler(pool, logger.With("subsystem", "telegram"))

	runCtx, runCancel := context.WithCancel(ctx)
	defer runCancel()
	go pollAllBots(runCtx, logger, pool, client, handler)

	reg, _ := observability.NewRegistry("telegramd")
	srv := httpserver.New(httpserver.Config{
		Addr:          cfg.HTTPAddr,
		ServiceName:   "telegramd",
		ShutdownGrace: cfg.ShutdownGrace,
	}, logger, observability.MetricsHandler(reg))

	errCh := make(chan error, 1)
	go func() { errCh <- srv.Start() }()
	select {
	case <-ctx.Done():
		logger.Info("shutdown signal received")
	case err := <-errCh:
		if err != nil {
			logger.Error("http server", "err", err)
			os.Exit(1)
		}
	}
	runCancel()
	time.Sleep(500 * time.Millisecond)
	if err := srv.Shutdown(ctx); err != nil {
		logger.Warn("graceful shutdown", "err", err)
	}
	logger.Info("bye")
}

// pollAllBots loads the bot list once at startup, then
// long-polls each in a goroutine. M3: a single reload on
// SIGUSR1 is overkill; restarting the binary picks up new
// bots. M5 can add a watch on the table.
func pollAllBots(ctx context.Context, logger *slog.Logger, pool *postgres.Pool, client telegram.BotClient, h *telegram.Handler) {
	bots, err := loadBots(ctx, pool)
	if err != nil {
		logger.Error("load bots", "err", err)
		return
	}
	logger.Info("loaded bots", "count", len(bots))
	if len(bots) == 0 {
		// No bots yet. Block on ctx so the process stays up.
		<-ctx.Done()
		return
	}
	for _, b := range bots {
		go pollOneBot(ctx, logger.With("bot", b.BotID, "company", b.CompanyID), client, h, b)
	}
	<-ctx.Done()
}

func loadBots(ctx context.Context, pool *postgres.Pool) ([]botConfig, error) {
	rows, err := pool.Query(ctx, `
		SELECT bot_id, company_id, bot_token
		  FROM telegram_bots
		 WHERE status = 'active'
		 ORDER BY company_id, bot_id
	`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []botConfig
	for rows.Next() {
		var b botConfig
		if err := rows.Scan(&b.BotID, &b.CompanyID, &b.BotToken); err != nil {
			return nil, err
		}
		out = append(out, b)
	}
	return out, rows.Err()
}

func pollOneBot(ctx context.Context, logger *slog.Logger, client telegram.BotClient, h *telegram.Handler, b botConfig) {
	var offset int64
	for {
		if ctx.Err() != nil {
			return
		}
		updates, err := client.GetUpdates(ctx, b.BotToken, offset, 25)
		if err != nil {
			if ctx.Err() != nil {
				return
			}
			logger.Warn("getUpdates", "err", err)
			time.Sleep(2 * time.Second)
			continue
		}
		for _, u := range updates {
			if u.UpdateID >= offset {
				offset = u.UpdateID + 1
			}
			if u.Message == nil {
				continue
			}
			reply, err := h.Handle(ctx, u.Message)
			if err != nil {
				logger.Warn("command handle", "err", err, "update_id", u.UpdateID)
				continue
			}
			if reply == "" {
				continue
			}
			if _, err := client.SendMessage(ctx, b.BotToken, u.Message.Chat.ID, reply); err != nil {
				logger.Warn("sendMessage reply", "err", err, "chat_id", u.Message.Chat.ID)
			}
		}
	}
}