package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"os/signal"
	"syscall"
)

var configPath *string = flag.String("c", "config.conf", "path to configuration file")
var showVersion *bool = flag.Bool("v", false, "show version")
var listProcesses *bool = flag.Bool("l", false, "list watched processes")

var addProcess *string = flag.String("a", "", "add process to list")
var removeProcess *string = flag.String("r", "", "remove process from list")

func main() {
	log.SetFlags(0)
	flag.Parse()

	if *showVersion {
		fmt.Println("httpprocprobed ver. 2.0.0")
		fmt.Println("Copyright (c) 2021,2022 Alexander \"Arav\" Andreev <me@arav.top>")
		fmt.Println("This program is licensed under terms of MIT+NIGGER license a copy")
		fmt.Println("of wich is located in /usr/share/licenses/httpprocprobed/LICENSE.")
		os.Exit(0)
	}

	conf, err := LoadConfiguration(*configPath)
	if err != nil {
		log.Fatalf("[ERR] Cannot load configuration file: %s\n", err)
	}

	if *listProcesses {
		for _, v := range conf.Processes {
			fmt.Printf("%s, ", v)
		}
		fmt.Println()
		os.Exit(0)
	}

	if *addProcess != "" {
		err := conf.AddProcess(*addProcess, *configPath)
		if err != nil {
			log.Fatalf("[ERR] Cannot add process: %s\n", err)
		}
	}

	if *removeProcess != "" {
		err := conf.RemoveProcess(*removeProcess, *configPath)
		if err != nil {
			log.Fatalf("[ERR] Cannot remove process: %s\n", err)
		}
	}

	// If we modified a list then let's look for a running program and
	// send SIGHUP to it to reload a list. Here we assume that there
	// is only one process running, so we just filter our PID.
	if *addProcess != "" || *removeProcess != "" {
		if err := conf.StoreConfiguration(*configPath); err != nil {
			log.Fatalf("[ERR] Cannot write configuration. Error: %s\n", err)
		}

		pids, _ := GetProcessPIDs("httpprocprobed")
		if len(pids) > 1 {
			var trgt_pid int
			if pids[0] == os.Getpid() {
				trgt_pid = pids[1]
			} else {
				trgt_pid = pids[0]
			}

			if proc, err := os.FindProcess(trgt_pid); err == nil {
				proc.Signal(syscall.SIGHUP)
			}
		}

		os.Exit(0)
	}

	srv := CreateAndStartHTTPServer(conf)

	syssignal := make(chan os.Signal, 1)
	signal.Notify(syssignal, os.Interrupt, syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP)

	log.Printf("httpprocprobed is running on \"%s\".", conf.ListenAddress)

	for {
		switch <-syssignal {
		case os.Interrupt:
			fallthrough
		case syscall.SIGINT | syscall.SIGTERM:
			ShutdownHTTPServer(srv)
			log.Println("Server shutted down.")
			os.Exit(0)
		case syscall.SIGHUP:
			newconf, err := LoadConfiguration(*configPath)
			if err != nil {
				log.Fatalf("Failed to reload a list of processes from configuration: %s\n", err)
			}
			conf.Processes = newconf.Processes
			log.Println("Successfully reloaded a list of watched processes.")
		}
	}
}