/* Copyright 2018 Martin Dosch

Licensed under the "MIT License" */

package main

import (
	"bufio"
	"errors"
	"io"
	"log"
	"os"
	"os/user"
	"strconv"
	"strings"
	"time"

	"github.com/mattn/go-xmpp"
	"github.com/pborman/getopt/v2"
	"mellium.im/xmpp/jid"
)

type configuration struct {
	username string
	jserver  string
	port     string
	password string
}

// Check that JIDs include localpart and serverpart
// and return it marshalled.
func marshalJID(input string) (string, error) {
	parsedJid, err := jid.Parse(input)
	if err != nil {
		return input, err
	}

	if parsedJid.Localpart() == "" || parsedJid.Domainpart() == "" {
		return input, errors.New("Invalid JID: " + input)
	}

	return parsedJid.String(), err
}

// Opens the config file and returns the specified values
// for username, server and port.
func parseConfig(configPath string) (configuration, error) {

	var (
		output configuration
		err    error
	)

	// Use ~/.sendxmpprc if no config path is specified.
	if configPath == "" {
		// Get systems user config path.
		osConfigDir := os.Getenv("$XDG_CONFIG_HOME")
		if osConfigDir != "" {
			configPath = osConfigDir + "/.sendxmpprc"
		} else {
			// Get the current user.
			curUser, err := user.Current()
			if err != nil {
				return output, err
			}
			// Get home directory.
			home := curUser.HomeDir
			if home == "" {
				return output, errors.New("No home directory found.")
			}
			configPath = home + "/.sendxmpprc"
		}
	}

	// Check that config file is existing.
	info, err := os.Stat(configPath)
	if os.IsNotExist(err) {
		return output, err
	}

	// Check for file permissions. Must be 600 or 400.
	perm := info.Mode().Perm()
	permissions := strconv.FormatInt(int64(perm), 8)
	if permissions != "600" && permissions != "400" {
		return output, errors.New("Wrong permissions for " + configPath + ": " +
			permissions + " instead of 600.")
	}

	// Open config file.
	file, err := os.Open(configPath)
	if err != nil {
		return output, err
	}
	defer file.Close()
	scanner := bufio.NewScanner(file)
	scanner.Split(bufio.ScanLines)

	// Read config file per line.
	for scanner.Scan() {
		if strings.HasPrefix(scanner.Text(), "#") == true {
			continue
		}

		row := strings.Split(scanner.Text(), " ")

		switch row[0] {
		case "username:":
			output.username = row[1]
		case "jserver:":
			output.jserver = row[1]
		case "password:":
			output.password = row[1]
		case "port:":
			output.port = row[1]
		default:
			if len(row) >= 2 {
				if strings.Contains(scanner.Text(), ";") == true {
					output.username = strings.Split(row[0], ";")[0]
					output.jserver = strings.Split(row[0], ";")[1]
					output.password = row[1]
				} else {
					output.username = strings.Split(row[0], ":")[0]
					output.jserver = strings.Split(row[0], "@")[1]
					output.password = row[1]
				}
			}
		}
	}

	return output, err
}

func readMessage(messageFilePath string) (string, error) {
	var (
		output string
		err    error
	)

	// Check that message file is existing.
	_, err = os.Stat(messageFilePath)
	if os.IsNotExist(err) {
		return output, err
	}

	// Open message file.
	file, err := os.Open(messageFilePath)
	if err != nil {
		return output, err
	}
	defer file.Close()
	scanner := bufio.NewScanner(file)
	scanner.Split(bufio.ScanLines)

	for scanner.Scan() {

		if output == "" {
			output = scanner.Text()
		} else {
			output = output + "\n" + scanner.Text()
		}
	}

	if err := scanner.Err(); err != nil {
		if err != io.EOF {
			return "", err
		}
	}

	return output, err
}

func main() {

	var (
		err     error
		message string
	)

	// Define command line flags.
	flagHelp := getopt.BoolLong("help", 0, "Show help.")
	flagDebug := getopt.BoolLong("debug", 'd', "Show debugging info.")
	flagServer := getopt.StringLong("jserver", 'j', "", "XMPP server address.")
	flagUser := getopt.StringLong("username", 'u', "", "Username for XMPP account.")
	flagPassword := getopt.StringLong("password", 'p', "", "Password for XMPP account.")
	flagChatroom := getopt.BoolLong("chatroom", 'c', "Send message to a chatroom.")
	flagTLS := getopt.BoolLong("tls", 't', "Use TLS.")
	flagStartTLS := getopt.BoolLong("start-tls", 'x', "Use StartTLS.")
	flagResource := getopt.StringLong("resource", 'r', "go-sendxmpp", "Set resource. "+
		"When sending to a chatroom this is used as 'alias'. (Default: go-sendxmpp)")
	flagFile := getopt.StringLong("file", 'f', "", "Set configuration file. (Default: ~/.sendxmpprc)")
	flagMessageFile := getopt.StringLong("message", 'm', "", "Set file including the message.")

	// Parse command line flags.
	getopt.Parse()

	// If requested, show help and quit.
	if *flagHelp {
		getopt.Usage()
		os.Exit(0)
	}

	// Read recipients from command line and quit if none are specified.
	recipients := getopt.Args()
	if len(recipients) == 0 {
		log.Fatal("No recipient specified.")
	}

	// Quit if unreasonable TLS setting is set.
	if *flagStartTLS == true && *flagTLS == true {
		log.Fatal("Use either TLS or StartTLS.")
	}

	// Check that all recipient JIDs are valid.
	for i, recipient := range recipients {
		validatedJid, err := marshalJID(recipient)
		if err != nil {
			log.Fatal(err)
		}
		recipients[i] = validatedJid
	}

	// Read configuration from file.
	config, err := parseConfig(*flagFile)
	if err != nil {
		log.Println("Error parsing ", *flagFile, ": ", err)
	}

	// Set connection options according to config.
	user := config.username
	server := config.jserver
	password := config.password
	if config.port != "" {
		server = server + ":" + config.port
	}

	// Overwrite user if specified via command line flag.
	if *flagUser != "" {
		user = *flagUser
	}

	// Overwrite server if specified via command line flag.
	if *flagServer != "" {
		server = *flagServer
	}

	// Overwrite password if specified via command line flag.
	if *flagPassword != "" {
		password = *flagPassword
	}

	// Set XMPP connection options.
	options := xmpp.Options{
		Host:     server,
		User:     user,
		Resource: *flagResource,
		Password: password,
		NoTLS:    !*flagTLS,
		StartTLS: *flagStartTLS,
		Debug:    *flagDebug,
	}

	// Read message from file.
	if *flagMessageFile != "" {
		message, err = readMessage(*flagMessageFile)
		if err != nil {
			log.Fatal(err)
		}
	}

	// Connect to server.
	client, err := options.NewClient()
	if err != nil {
		log.Fatal(err)
	}

	if message == "" {

		scanner := bufio.NewScanner(os.Stdin)
		for scanner.Scan() {

			if message == "" {
				message = scanner.Text()
			} else {
				message = message + "\n" + scanner.Text()
			}
		}

		if err := scanner.Err(); err != nil {
			if err != io.EOF {
				log.Fatal(err)
			}
		}
	}

	// Send message to chatroom(s) if the flag is set.
	if *flagChatroom {

		for _, recipient := range recipients {

			// Join the MUC.
			mucStatus, err := client.JoinMUCNoHistory(recipient, *flagResource)
			if err != nil {
				log.Fatal(err)
			}

			// Exit if Status is > 300, see https://xmpp.org/registrar/mucstatus.html
			if mucStatus > 300 {
				log.Fatal("Couldn't join MUC. Status:", mucStatus)
			}

			// Send the message.
			_, err = client.Send(xmpp.Chat{Remote: recipient, Type: "groupchat", Text: message})
			if err != nil {
				log.Fatal(err)
			}

			// After sending the message, leave the Muc
			_, err = client.LeaveMUC(recipient)
			if err != nil {
				log.Println(err)
			}
		}
	} else {

		for _, recipient := range recipients {

			// If the chatroom flag is not set, send message to contact(s).
			_, err = client.Send(xmpp.Chat{Remote: recipient, Type: "chat", Text: message})
			if err != nil {
				log.Fatal(err)
			}
		}
	}
	time.Sleep(1 * time.Second)
}