package lockserver

import (
	"bufio"
	"fmt"
	"net"
	"os"
	"strconv"
	"strings"
	"time"	

	log "github.com/sirupsen/logrus"
)

// Build key encoding request command for the Omnitec lock server.
func (lock *OmniLockServer) BuildCommand(doorReq DoorCardRequest, checkIn, checkOut time.Time) error {
	const funcName = "OmniLockServer.BuildCommand"
	hostname, err := os.Hostname()
	if err != nil {
		return fmt.Errorf("[%s] failed to get hostname: %v", funcName, err)
	}

	// Format lockId as 4-digit zero-padded string
	idInt, err := strconv.Atoi(doorReq.RoomField)
	if err != nil {
		return fmt.Errorf("[%s] failed to convert lockId to integer: %v", funcName, err)
	}
	formattedLockId := fmt.Sprintf("%04d", idInt)

	// Format date/time parts
	dt := checkOut.Format("15:04")  // DT = HH:mm
	ga := checkIn.Format("060102")  // GA = ddMMyy
	gd := checkOut.Format("060102") // GD = ddMMyy
	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|",
		lock.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
}

// Starts link to the Omnitec lock server and perform key encoding
func (lock *OmniLockServer) LockSequence() error {
	const funcName = "OmniLockServer.LockSequence"

	conn, err := InitializeServerConnection(LockServerURL)
	if err != nil {
		return err
	}
	defer conn.Close()

	// Start the link with the lock server
	regs, err := lock.linkStart(conn)
	if err != nil {
		return fmt.Errorf("[%s] linkStart failed: %v", funcName, err)
	}
	for _, reg := range regs {
		log.Printf("Received: %q", reg)
	}

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

	return nil
}

func (lock *OmniLockServer) linkStart(conn net.Conn) ([]string, error) {
	payload := fmt.Sprintf("LS|DA%s|TI%s|",
		time.Now().Format("060102"),
		time.Now().Format("150405"),
	)
	command := append([]byte{0x02}, append([]byte(payload), 0x03)...)

	log.Printf("Sending command: %q", command)
	_, err := conn.Write(command)
	if err != nil {
		return nil, fmt.Errorf("failed to send command: %v", err)
	}

	conn.SetReadDeadline(time.Now().Add(10 * time.Second))
	reader := bufio.NewReader(conn)

	var registers []string
	for {
		reg, err := reader.ReadString(0x03)
		if err != nil {
			if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
				break // timeout -> assume no more registers
			}
			return nil, fmt.Errorf("error reading register: %v", err)
		}

		registers = append(registers, reg)

		// stop when you see the final register type, e.g. "LA|…|<ETX>"
		if strings.HasPrefix(reg, "\x02LA|") {
			break
		}
	}

	return registers, nil
}

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

	return parseOmniResponse(raw)
}

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
}