// ollie-httpgw - HTTP gateway for ollie session management.
//
// Translates HTTP requests to D-Bus calls against org.ollie.SessionManager.
//
// Usage:
//
//	ollie-httpgw [start|fgstart|stop|status]
package main

import (
	_ "embed"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"net"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"syscall"
)

//go:embed openapi.json
var openapiSpec []byte

var listen = flag.String("listen", ":8011", "HTTP listen address")

const pidFile = "ollie-httpgw.pid"

func main() {
	args := os.Args[1:]

	if len(args) >= 1 {
		subcmd := args[0]
		switch subcmd {
		case "start", "fgstart", "stop", "status":
			flag.CommandLine.Parse(args[1:]) //nolint:errcheck
			ns := os.Getenv("NAMESPACE")
			if ns == "" {
				ns = fmt.Sprintf("/tmp/ns.%s.:0", os.Getenv("USER"))
			}
			pidPath := filepath.Join(ns, pidFile)
			switch subcmd {
			case "start":
				if gwRunning() {
					fmt.Println("ollie-httpgw already running")
					os.Exit(0)
				}
				daemonize()
			case "fgstart":
				if gwRunning() {
					fmt.Println("ollie-httpgw already running")
					os.Exit(0)
				}
				runGateway(pidPath)
			case "stop":
				stopGateway(pidPath)
			case "status":
				if gwRunning() {
					fmt.Println("ollie-httpgw running")
				} else {
					fmt.Println("ollie-httpgw not running")
					os.Exit(1)
				}
			}
			return
		}
	}

	// No subcommand — run in foreground directly (no pid file).
	flag.CommandLine.Parse(args) //nolint:errcheck
	serve()
}

func gwRunning() bool {
	conn, err := net.Dial("tcp", *listen)
	if err == nil {
		conn.Close()
		return true
	}
	return false
}

func daemonize() {
	exe, _ := os.Executable()
	args := []string{"fgstart", "-listen", *listen}
	cmd := exec.Command(exe, args...)
	cmd.SysProcAttr = &syscall.SysProcAttr{Setsid: true}
	if err := cmd.Start(); err != nil {
		fmt.Fprintf(os.Stderr, "failed to start: %v\n", err)
		os.Exit(1)
	}
	fmt.Printf("ollie-httpgw started (pid %d)\n", cmd.Process.Pid)
}

func stopGateway(pidPath string) {
	data, err := os.ReadFile(pidPath)
	if err != nil {
		fmt.Println("ollie-httpgw not running")
		return
	}
	var pid int
	fmt.Sscanf(string(data), "%d", &pid)
	if pid > 0 {
		syscall.Kill(pid, syscall.SIGTERM) //nolint:errcheck
	}
	os.Remove(pidPath) //nolint:errcheck
	fmt.Println("ollie-httpgw stopped")
}

func runGateway(pidPath string) {
	os.WriteFile(pidPath, fmt.Appendf(nil, "%d", os.Getpid()), 0644) //nolint:errcheck
	serve()
	os.Remove(pidPath) //nolint:errcheck
}

func serve() {
	http.HandleFunc("/openapi.json", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		w.Write(openapiSpec)
	})

	http.HandleFunc("/", dbusHandler)

	log.Printf("ollie-httpgw listening on %s", *listen)
	log.Fatal(http.ListenAndServe(*listen, nil))
}

func writeJSON(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(v)
}