// Command updater-master serves the package-updater UI and accepts agent
// connections.
package main

import (
	"context"
	"crypto/tls"
	"errors"
	"fmt"
	"net"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
	"strings"
	"syscall"
	"time"

	"github.com/shcizo/package-updater/internal/logging"
	"github.com/shcizo/package-updater/internal/master/config"
	"github.com/shcizo/package-updater/internal/master/events"
	"github.com/shcizo/package-updater/internal/master/hub"
	"github.com/shcizo/package-updater/internal/master/jobs"
	"github.com/shcizo/package-updater/internal/master/poller"
	"github.com/shcizo/package-updater/internal/master/registry"
	"github.com/shcizo/package-updater/internal/master/store"
	"github.com/shcizo/package-updater/internal/master/web"
	"github.com/shcizo/package-updater/internal/master/webauth"
	"github.com/shcizo/package-updater/internal/master/webhook"
	"github.com/shcizo/package-updater/internal/pin"
)

// Build info is injected at link time via -ldflags="-X main.version=...".
var version = "dev"

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

// pollFirstDelay is how long the master runs before its first registry
// polling cycle, so agents have reported their inventory.
const pollFirstDelay = time.Minute

// pollWorkers is how many registry lookups run at once.
const pollWorkers = 4

// registryCredentialsDir returns the directory the registry client reads
// credentials from (DOCKER_CONFIG, else ~/.docker), whether a config.json is
// in it, and the error from opening it when it exists but cannot be read (for
// example because the master runs as another user than the file owner). The
// file is opened and closed, never read; only the path is logged.
func registryCredentialsDir() (dir string, found bool, readErr error) {
	dir = os.Getenv("DOCKER_CONFIG")
	if dir == "" {
		home, err := os.UserHomeDir()
		if err != nil {
			return "", false, nil
		}
		dir = filepath.Join(home, ".docker")
	}
	path := filepath.Join(dir, "config.json")
	if _, err := os.Stat(path); err != nil {
		return dir, false, nil
	}
	f, err := os.Open(path)
	if err != nil {
		return dir, true, err
	}
	_ = f.Close()
	return dir, true, nil
}

func run() error {
	cfg, err := config.Load()
	if err != nil {
		return err
	}
	logger := logging.New(cfg.LogLevel)
	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	st, err := store.Open(ctx, cfg.DatabaseURL)
	if err != nil {
		return err
	}
	defer st.Close()

	key, err := st.LoadOrCreateIdentity(ctx, pin.GenerateKey)
	if err != nil {
		return err
	}
	cert, err := pin.Certificate(key)
	if err != nil {
		return err
	}
	fingerprint, err := pin.Fingerprint(key.Public())
	if err != nil {
		return err
	}
	logger.Info("master_starting", "version", version, "master_key", fingerprint)

	broker := events.NewBroker()
	agentHub := hub.New(st, broker, logger)
	jobService := jobs.New(st, agentHub, broker, cfg.AgentImage, logger)

	provider, err := webauth.NewOIDCProvider(ctx, webauth.OIDCConfig{
		Issuer: cfg.OIDCIssuer, ClientID: cfg.OIDCClientID, ClientSecret: cfg.OIDCClientSecret,
		RedirectURL: cfg.PublicURL + "/auth/callback",
	})
	if err != nil {
		return err
	}
	auth := webauth.New(provider, st, cfg.AllowedGroup, strings.HasPrefix(cfg.PublicURL, "https://"), logger)

	credDir, credFound, credReadErr := registryCredentialsDir()
	logger.Info("registry_credentials", "docker_config", credDir, "config_json_found", credFound,
		"config_json_readable", credFound && credReadErr == nil)
	if credReadErr != nil {
		logger.Warn("registry_credentials_unreadable", "docker_config", credDir, "error", credReadErr)
	}
	registryPoller := poller.New(st, jobService, registry.New("package-updater-master/"+version, logger), broker, poller.Config{
		Interval: cfg.PollInterval, FirstDelay: pollFirstDelay, Workers: pollWorkers,
	}, logger)

	ui, err := web.New(st, agentHub, jobService, broker, registryPoller, web.Config{
		AgentURL: cfg.AgentURL, MasterKey: fingerprint, AgentImage: cfg.AgentImage,
		PollInterval: cfg.PollInterval, Version: version,
	}, logger)
	if err != nil {
		return err
	}

	mux := http.NewServeMux()
	mux.HandleFunc("GET /healthz", func(w http.ResponseWriter, r *http.Request) {
		if err := st.Ping(r.Context()); err != nil {
			http.Error(w, "database unreachable", http.StatusServiceUnavailable)
			return
		}
		_, _ = w.Write([]byte("ok"))
	})
	// The webhook does its own bearer-token check, so it sits outside the
	// OIDC login like /healthz.
	mux.Handle("POST /update", webhook.New(st, jobService, broker, webhook.Config{
		Token: cfg.UpdaterAPIKey, Timeout: cfg.UpdateTimeout, PublicURL: cfg.PublicURL,
	}, logger))
	if cfg.UpdaterAPIKey == "" {
		logger.Warn("webhook_disabled", "reason", "UPDATER_API_KEY not set")
	}
	mux.HandleFunc("GET /auth/login", auth.Login)
	mux.HandleFunc("GET /auth/callback", auth.Callback)
	mux.Handle("POST /auth/logout", auth.Require(http.HandlerFunc(auth.Logout)))
	ui.Register(mux, auth.Require)

	// BaseContext ties every request context to the signal context, so on
	// shutdown the long-lived SSE handlers and agent connections return
	// instead of holding Shutdown until its timeout.
	baseContext := func(net.Listener) context.Context { return ctx }

	// No WriteTimeout on either server: SSE streams, agent connections and
	// POST /update (which waits up to UPDATE_TIMEOUT) are long-lived by design.
	webSrv := &http.Server{
		Addr: ":" + cfg.Port, Handler: mux, ReadHeaderTimeout: 10 * time.Second,
		BaseContext: baseContext,
	}

	agentMux := http.NewServeMux()
	agentMux.Handle("GET /agent", agentHub)
	agentSrv := &http.Server{
		Addr: ":" + cfg.AgentPort, Handler: agentMux, ReadHeaderTimeout: 10 * time.Second,
		TLSConfig:   &tls.Config{Certificates: []tls.Certificate{cert}, MinVersion: tls.VersionTLS13},
		BaseContext: baseContext,
	}

	pollCtx, stopPolling := context.WithCancel(ctx)
	defer stopPolling()
	pollDone := make(chan struct{})
	go func() {
		defer close(pollDone)
		registryPoller.Run(pollCtx)
	}()

	errCh := make(chan error, 2)
	go func() { errCh <- webSrv.ListenAndServe() }()
	go func() { errCh <- agentSrv.ListenAndServeTLS("", "") }()
	logger.Info("listening", "web", webSrv.Addr, "agents", agentSrv.Addr)

	var serveErr error
	select {
	case <-ctx.Done():
		logger.Info("shutdown_signal")
	case err := <-errCh:
		if !errors.Is(err, http.ErrServerClosed) {
			serveErr = err
		}
	}
	shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	_ = webSrv.Shutdown(shutdownCtx)
	_ = agentSrv.Shutdown(shutdownCtx)
	// The poller writes to the store, which is closed when run returns.
	stopPolling()
	<-pollDone
	return serveErr
}