package lockserver

import (
	"bufio"
	// "io"
	"fmt"
	"net"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"

	log "github.com/sirupsen/logrus"
)

const (
	AssaAbloy = "assaabloy"
	Omnitec   = "omnitec"
)

type (
	LockServer interface {
		LockSequence(conn net.Conn) error
		BuildCommand(encoderAddr, lockId string, checkIn, checkOut time.Time) error
	}

	AssaLockServer struct {
		command string
	}

	OmniLockServer struct {
		command []byte // Command to be sent to the lock server
	}
)

func InitializeServerConnection(LockserverUrl string) (net.Conn, error) {
	const funcName = "InitializeServerConnection"
	// Parse the URL to extract host and port
	parsedUrl, err := url.Parse(LockserverUrl)
	if err != nil {
		return nil, fmt.Errorf("[%s] failed to parse LockserverUrl: %v", funcName, err)
	}

	// Remove any leading/trailing slashes just in case
	address := strings.Trim(parsedUrl.Host, "/")

	// Establish a TCP connection to the Visionline server
	conn, err := net.Dial("tcp", address)
	if err != nil {
		return nil, fmt.Errorf("failed to connect to Visionline server: %v", err)
	}
	return conn, nil
}

// sendAndReceive sends a command to the lock server and waits for a response.
func sendAndReceive(conn net.Conn, command []byte) (string, error) {
	const funcName = "SendAndReceive"
	// Write the command to the connection
	log.Printf("Sending command: %q", command)
	_, err := conn.Write(command)
	if err != nil {
		return "", fmt.Errorf("failed to send command: %v", err)
	}

	conn.SetReadDeadline(time.Now().Add(10 * time.Second))

	buf := make([]byte, 128)
	reader := bufio.NewReader(conn)
	n, err := reader.Read(buf)
	if err != nil {
		return "", fmt.Errorf("error reading response: %v", err)
	}
	response := buf[:n]
	return string(response), nil
}

func parseAssaResponse(raw string) (string, error) {
	clean := strings.ReplaceAll(raw, "\r\n", "")
	idx := strings.Index(clean, "RC")
	code := clean[idx+2 : idx+3] // Extract the response code
	if code != "0" {
		return "", fmt.Errorf("negative response code: %s", clean)
	}
	return "Success: " + clean, nil
}

func parseOmniResponse(raw string) (string, error) {
	clean := strings.Trim(raw, "\x02\x03")
	idx := strings.Index(clean, "AS")
	code := clean[idx+2 : idx+4] // Extract the response code
	code = strings.ToLower(code) // Convert to lowercase for consistency
	if code != "ok" {
		return "", fmt.Errorf("negative response code: %s", clean)
	}
	return "Success: " + clean, nil
}

func sendHeartbeatToServer(conn net.Conn) (string, error) {
	const heartbeatRegister = "CCC;EAHEARTBEAT;AM1;\r\n"

	raw, err := sendAndReceive(conn, []byte(heartbeatRegister))
	if err != nil {
		return "", fmt.Errorf("failed to send Heartbeat command: %v", err)
	}

	return parseAssaResponse(raw)
}

func requestEncoding(conn net.Conn, command string) (string, error) {
	// 1) Send and read raw response
	raw, err := sendAndReceive(conn, []byte(command))
	if err != nil {
		return "", fmt.Errorf("failed to send Encoding request: %v", err)
	}

	return parseAssaResponse(raw)
}

func (lock *AssaLockServer) LockSequence(conn net.Conn) error {
	resp, err := sendHeartbeatToServer(conn)
	if err != nil {
		return fmt.Errorf("lock server heartbeat failed: %v", err)
	}
	log.Infof("Heartbeat response: %s", resp)

	resp, err = requestEncoding(conn, lock.command)
	if err != nil {
		return fmt.Errorf("lock server request encoding failed: %v", err)
	}
	log.Infof("Encoding response: %s", resp)
	return nil
}

func (lock *AssaLockServer) BuildCommand(encoderAddr, lockId string, checkIn, checkOut time.Time) error {
	ci := checkIn.Format("200601021504")
	co := checkOut.Format("200601021504")

	lock.command = fmt.Sprintf("CCA;EA%s;GR%s;CO%s;CI%s;AM1;\r\n", encoderAddr, lockId, co, ci)
	return nil
}

func (lock *OmniLockServer) BuildCommand(encoderAddr, lockId string, checkIn, checkOut time.Time) error {
	hostname, err := os.Hostname()
	if err != nil {
		return fmt.Errorf("could not get hostname: %v", err)
	}

	// Format lockId as 4-digit zero-padded string
	idInt, err := strconv.Atoi(lockId)
	if err != nil {
		return fmt.Errorf("invalid lockId %q: %v", lockId, err)
	}
	formattedLockId := fmt.Sprintf("%04d", idInt)

	// Format date/time parts
	ga := checkIn.Format("020106")  // GA = ddMMyy
	gd := checkOut.Format("020106") // GD = ddMMyy
	dt := checkIn.Format("15:04")   // DT = HH:mm
	ti := checkIn.Format("150405")  // TI = HHmmss

	// Construct payload
	payload := fmt.Sprintf(
		"KR|KC%s|KTD|RN%s|%s|DT%s|G#75|GA%s|GD%s|KO0000|DA%s|TI%s|",
		encoderAddr,
		formattedLockId,
		hostname,
		dt,
		ga,
		gd,
		ga,
		ti,
	)

	// Assign to command field with STX and ETX
	lock.command = append([]byte{0x02}, append([]byte(payload), 0x03)...)

	return nil
}

func (lock *OmniLockServer) LockSequence(conn net.Conn) error {
	const funcName = "OmniLockServer.LockSequence"
	// Start the link with the lock server
	raw, err := lock.linkStart(conn)
	if err != nil {
		return fmt.Errorf("[%s] linkStart failed: %v", funcName, err)
	}
	log.Infof("Link start response: %s", raw)

	// Request encoding from the lock server
	raw, err = lock.requestEncoding(conn)
	if err != nil {
		return fmt.Errorf("[%s] requestEncoding failed: %v", funcName, err)
	}
	log.Infof("Encoding response: %s", raw)

	return nil
}

func (lock *OmniLockServer) linkStart(conn net.Conn) (string, error) {
	const funcName = "OmniLockServer.linkStart"
	// Send the link start command
	payload := fmt.Sprintf("LS|DA%s|TI%s|", time.Now().Format("020106"), time.Now().Format("150405"))
	command := append([]byte{0x02}, append([]byte(payload), 0x03)...)

	raw, err := sendAndReceive(conn, command)
	if err != nil {
		return "", fmt.Errorf("failed to send Link Start command: %v", err)
	}
	return raw, nil
}

func (lock *OmniLockServer) requestEncoding(conn net.Conn) (string, error) {
	const funcName = "OmniLockServer.requestEncoding"
	// Send the encoding request command
	raw, err := sendAndReceive(conn, lock.command)
	if err != nil {
		return "", fmt.Errorf("failed to send Encoding request: %v", err)
	}

	return parseOmniResponse(raw) 
}