/*
Package door: a go implementation of a BBS door for linux and Windows
that uses door32.sys, understand CP437 and unicode (if available),
detects screen size, and supports TheDraw Fonts.

    import (
			"door"
		)

	int main() {
		d = door.Door{}
		d.Init() // Process commandline switches, initialize door, detect screen size.

		d.Write("Welcome to my awesome door, written in "+door.ColorText("BLINK BOLD WHITE")+"go"+door.Reset+"."+door.CRNL)
		d.Write("Press a key...")
		d.Key()
		d.Write(door.CRNL)
	}
*/
package door

import (
	"bufio"
	"flag"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"sync"
	"time"
	"runtime/debug"
	"sync/atomic"
)

const SavePos = "\x1b[s"              // Save Cursor Position
const RestorePos = "\x1b[u"           // Restore Cursor Position
const CRNL = "\r\n"                   // BBS Line Ending
const Clrscr = "\x1b[0m\x1b[2J\x1b[H" // Clear screen, home cursor
const HideCursor = "\x1b[?25l"        // Hide Cursor
const ShowCursor = "\x1b[?25h"        // Show Cursor
var Reset string = Color(0)           // ANSI Color Reset
var Unicode bool                      // Unicode support detected
var CP437 bool                        // CP437 support detected
var Full_CP437 bool                   // Full CP437 support detected (handles control codes properly)
var Height int                        // Screen height detected
var Width int                         // Screen width detected
var Inactivity int64 = 120            // Inactivity timeout

/*
door32.sys:

0                            Line 1 : Comm type (0=local, 1=serial, 2=telnet)
0                            Line 2 : Comm or socket handle
38400                        Line 3 : Baud rate
Mystic 1.07                  Line 4 : BBSID (software name and version)
1                            Line 5 : User record position (1-based)
James Coyle                  Line 6 : User's real name
g00r00                       Line 7 : User's handle/alias
255                          Line 8 : User's security level
58                           Line 9 : User's time left (in minutes)
1                            Line 10: Emulation *See Below
1                            Line 11: Current node number
*/

// Door32 information
type DropfileConfig struct {
	Comm_type      int    // (not used)
	Comm_handle    int    // Handle to use to talk to the user
	Baudrate       int    // (not used)
	BBSID          string // BBS Software name
	User_number    int    // User number
	Real_name      string // User's Real Name
	Handle         string // User's Handle/Nick
	Security_level int    // Security Level (if given)
	Time_left      int    // Time Left (minutes)
	Emulation      int    // (not used)
	Node           int    // BBS Node number
}

type Door struct {
	Config        DropfileConfig
	READFD        int
	WRITEFD       int
	Disconnected  int32	// atomic bool      // Has User disconnected/Hung up?
	TimeOut       time.Time // Fixed point in time, when time expires
	StartTime     time.Time // Time when User started door
	Pushback      FIFOBuffer
	LastColor     []int
	readerChannel chan byte   // Reading from the User
	writerChannel chan string // Writing to the User
	closeChannel  chan bool   // Closing
	wg            sync.WaitGroup
	writerMutex   sync.Mutex
}

// Return the amount of time left as time.Duration
func (d *Door) TimeLeft() time.Duration {
	return time.Until(d.TimeOut)
}

func (d *Door) TimeUsed() time.Duration {
	return time.Since(d.StartTime)
}

func (d *Door) Disconnect() bool {
	return atomic.LoadInt32(&d.Disconnected) != 0
}

// Read the BBS door file.  We only support door32.sys.
func (d *Door) ReadDropfile(filename string) {
	file, err := os.Open(filename)
	if err != nil {
		log.Panicf("Open(%s): %s\n", filename, err)
	}

	defer file.Close()

	var lines []string
	// read line by line
	// The scanner handles DOS and linux file endings.

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := scanner.Text()
		lines = append(lines, line)
	}

	d.Config.Comm_type, err = strconv.Atoi(lines[0])
	if err != nil {
		log.Panicf("Door32 Comm Type (expected integer): %s\n", err)
	}
	d.Config.Comm_handle, err = strconv.Atoi(lines[1])
	if err != nil {
		log.Panicf("Door32 Comm Handle (expected integer): %s\n", err)
	}
	d.Config.Baudrate, err = strconv.Atoi(lines[2])
	if err != nil {
		log.Panicf("Door32 Baudrate (expected integer): %s\n", err)
	}
	d.Config.BBSID = lines[3]
	d.Config.User_number, err = strconv.Atoi(lines[4])
	if err != nil {
		log.Panicf("Door32 User Number (expected integer): %s\n", err)
	}
	d.Config.Real_name = lines[5]
	d.Config.Handle = lines[6]
	d.Config.Security_level, err = strconv.Atoi(lines[7])
	if err != nil {
		log.Panicf("Door32 Security Level (expected integer): %s\n", err)
	}
	d.Config.Time_left, err = strconv.Atoi(lines[8])
	if err != nil {
		log.Panicf("Door32 Time Left (expected integer): %s\n", err)
	}
	d.Config.Emulation, err = strconv.Atoi(lines[9])
	if err != nil {
		log.Panicf("Door32 Emulation (expected integer): %s\n", err)
	}
	d.Config.Node, err = strconv.Atoi(lines[10])
	if err != nil {
		log.Panicf("Door32 Node Number (expected integer): %s\n", err)
	}

	d.READFD = d.Config.Comm_handle
	d.WRITEFD = d.Config.Comm_handle

	d.StartTime = time.Now()
	// Calculate when time expires.
	d.TimeOut = time.Now().Add(time.Duration(d.Config.Time_left) * time.Minute)
}

// Detect client terminal capabilities, Unicode, CP437, Full_CP437,
// screen Height and Width.
// Full_CP437 means the terminal understands control codes as CP437.
func (d *Door) detect() {
	d.Write("\x1b[0;30;40m\x1b[2J\x1b[H")                          // black on black, clrscr, go home
	d.Write("\x03\x04\x1b[6n")                                     // hearts and diamonds does CP437 work?
	d.Write(CRNL + "\u2615\x1b[6n")                                // hot beverage
	d.Write("\x1b[999C\x1b[999B\x1b[6n" + Reset + "\x1b[2J\x1b[H") // goto end of screen + cursor pos
	time.Sleep(250 * time.Millisecond)

	// read everything
	var results string

	for {
		r := d.getch()
		if r < 0 {
			break
		}
		results += string(byte(r))
	}

	if len(results) > 0 {
		output := strings.Replace(results, "\x1b", "^[", -1)
		log.Println("DETECT:", output)
	} else {
		log.Println("DETECT: Nothing received.")
		return
	}

	if (strings.Contains(results, "1;1R") ||
		strings.Contains(results, "1;3R")) &&
		(strings.Contains(results, "2:2R") ||
			strings.Contains(results, "2;3R")) {
		Unicode = true
	} else {
		Unicode = false
		CP437 = true
	}
	if strings.Contains(results, "1;3R") {
		Full_CP437 = true
	}

	// get screen size
	pos := strings.LastIndex(results, "\x1b")
	if pos != -1 {
		pos++
		if results[pos] == '[' {
			pos++
			results = results[pos:]
			pos = strings.Index(results, ";")
			if pos != -1 {
				height := results[:pos]
				Height, _ = strconv.Atoi(height)
				pos++
				results = results[pos:]

				pos = strings.Index(results, "R")
				if pos != -1 {
					width := results[:pos]

					Width, _ = strconv.Atoi(width)
				}
			} else {
				Height = 0
				Width = 0
			}
		}
	}
	log.Printf("Unicode %v Screen: %d X %d\n", Unicode, Width, Height)
}

// Initialize door framework.  Parse commandline, read dropfile,
// detect terminal capabilities.
func (d *Door) Init(doorname string) {
	var dropfile string
	d.Pushback = NewFIFOBuffer(5)

	// Get path to binary, and chdir to it.
	binaryPath, _ := os.Executable()
	binaryPath = filepath.Dir(binaryPath)
	_ = os.Chdir(binaryPath)

	flag.StringVar(&dropfile, "d", "", "Path to dropfile")
	flag.Parse()
	if len(dropfile) == 0 {
		flag.PrintDefaults()
		os.Exit(2)
	}

	d.ReadDropfile(dropfile)

	// Logfile will be doorname - node #
	logfilename := fmt.Sprintf("%s-%d.log", doorname, d.Config.Node)
	logf, err := os.OpenFile(logfilename, os.O_APPEND|os.O_CREATE|os.O_RDWR, 0666)
	if err != nil {
		log.Panicf("Error creating log file %s: %v", logfilename, err)
	}

	log.SetOutput(logf)
	log.SetFlags(log.Ldate | log.Ltime | log.Lshortfile)
	log.Printf("Loading dropfile %s\n", dropfile)
	log.Printf("BBS %s, User %s / Handle %s / File %d\n", d.Config.BBSID, d.Config.Real_name, d.Config.Handle, d.Config.Comm_handle)

	d.readerChannel = make(chan byte, 8)
	d.writerChannel = make(chan string)
	d.closeChannel = make(chan bool, 2) // reader & door.Close

	d.setupChannels()

	d.detect()
	if Unicode {
		BOXES = BOXES_UNICODE
		BARS = BARS_UNICODE
	} else {
		BOXES = BOXES_CP437
		BARS = BARS_CP437
	}
}

func (d *Door) Close() {
        defer func() {
                if err := recover(); err != nil {
                        log.Println("door.Close FAILURE:", err)
                        // This displays stack trace stderr
                        debug.PrintStack()
                }
        }()

	log.Println("Closing...")
	d.closeChannel <- true
	if ! d.Disconnect() {
		// log.Println("close write channel")
		// close(d.writerChannel)
		log.Println("close read handle")
		CloseReader(d.Config.Comm_handle)
		log.Println("closed read handle")
	}

	// d.closeChannel <- true
	// close(d.closeChannel)
	log.Println("wg.Wait()")
	d.wg.Wait()
	log.Println("Closed.")
}

// Goto X, Y - Position the cursor using ANSI Escape Codes
//
// Example:
//     d.Write(door.Goto(1, 5) + "Now at X=1, Y=5.")
func Goto(x int, y int) string {
	return fmt.Sprintf("\x1b[%d;%dH", y, x)
}