// Command cyrene is the single Cyrene v2 binary. It assembles every subsystem
// (config, logging, database, bus, personas, model adapter, tool dispatcher,
// memory stack, agent loop, orchestration, execution, IoT, channel sessions and
// adapters) into one process and serves the gateway + embedded frontend on a
// single port (:8080), shutting down gracefully on a termination signal.
//
// Build with `go build -ldflags="-s -w" -trimpath -o cyrene ./cmd/cyrene/`.
// The frontend must be built first so the SPA can be embedded:
// `cd frontend/web && npm run build`.
package main

import (
	"context"
	"fmt"
	"io/fs"
	"log/slog"
	"os"
	"path/filepath"
	"time"
	// Embed the IANA timezone database so the configured TZ (config.TZ, default
	// "Asia/Shanghai") resolves everywhere: Windows ships no system tzdata and Go
	// deliberately does not bundle one, so without this the loop's time injection
	// silently disables itself there (internal/runtime/loop/time.go logs
	// "timezone load failed"). Costs ~450 KB and keeps the binary self-contained.
	_ "time/tzdata"

	capreg "git.yeij.top/AskaEth/Cyrene_v2/internal/capability/registry"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/config"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/logger"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/platform"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/webui"
)

// envPath is the .env file merged at boot (development only; production uses
// systemd/env_file). A missing .env is not an error.
const envPath = ".env"

// shutdownTimeout bounds how long the graceful teardown may take.
const shutdownTimeout = 15 * time.Second

// externalDistCandidates are the on-disk directories checked (in order) for a
// frontend override before falling back to the embedded dist. The first that
// exists wins. They are relative to the process working directory.
func externalDistCandidates() []string {
	return []string{
		filepath.Join("frontend", "web", "dist"),
		filepath.Join("frontend", "dist"),
	}
}

// resolveFrontendFS returns the filesystem serving the SPA: an external dist
// directory when present (deploy-time hot override), otherwise the embedded dist.
func resolveFrontendFS(log *slog.Logger) fs.FS {
	for _, dir := range externalDistCandidates() {
		if info, err := os.Stat(dir); err == nil && info.IsDir() {
			log.Info("serving external frontend dist", "dir", dir)
			return os.DirFS(dir)
		}
	}
	log.Info("serving embedded frontend dist")
	return webui.Assets()
}

func main() {
	if err := run(); err != nil {
		fmt.Fprintln(os.Stderr, "cyrene:", err)
		os.Exit(1)
	}
}

// run boots the application, starts every service and the gateway, then blocks
// until a termination signal arrives or the gateway fails.
func run() error {
	cfg := config.MustLoad(envPath)
	format := logger.FormatText
	if cfg.Env == "production" {
		format = logger.FormatJSON
	}
	logRing := logger.NewRingBuffer(logger.DefaultRingCapacity)
	log := logger.New(logger.Options{Level: cfg.LogLevel, Format: string(format), Ring: logRing})
	log = logger.WithSource(log, "main")

	ctx, stop := platform.SignalContext()
	defer stop()

	a, err := newApp(ctx, cfg, log)
	if err != nil {
		return err
	}
	// Observability log tail: the logger's ring buffer is built above (before the
	// gateway), so hand it to the gateway now that the gateway exists.
	wireGatewayLogBuffer(a, logRing)

	if err := a.automation.Start(ctx); err != nil {
		return fmt.Errorf("start automations: %w", err)
	}
	a.backthink.Start(ctx)
	a.log.Info("cyrene subsystems started",
		"personas", a.personas.CountPersonas(),
		"tools", len(a.caps.List(capreg.KindTool)),
		"channels", len(a.caps.List(capreg.KindChannel)))
	a.log.Info("cyrene ready", "data_dir", resolveDataDir(cfg))

	errCh, err := a.gw.Start(ctx)
	if err != nil {
		return fmt.Errorf("start gateway: %w", err)
	}

	select {
	case <-ctx.Done():
		a.log.Info("cyrene signal received, shutting down")
	case gwErr := <-errCh:
		if gwErr != nil {
			shutCtx, cancel := context.WithTimeout(context.Background(), shutdownTimeout)
			defer cancel()
			a.close(shutCtx)
			return fmt.Errorf("gateway failed: %w", gwErr)
		}
	}

	shutCtx, cancel := context.WithTimeout(context.Background(), shutdownTimeout)
	defer cancel()
	a.close(shutCtx)
	return nil
}