package capture

import (
	"bufio"
	"errors"
	"fmt"
	"io"
	"strconv"
	"strings"

	"tea.chunkbyte.com/kato/go-worm/lib/config"
	"tea.chunkbyte.com/kato/go-worm/lib/models"
)

var ErrMonitorNotFound = errors.New("monitor not found")

func writeRequest(w io.Writer, monitor int, format string, quality int) error {
	_, err := fmt.Fprintf(w, "C %d %s %d\n", monitor, format, quality)
	return err
}

func readRequest(r *bufio.Reader) (monitor int, format string, quality int, err error) {
	line, err := r.ReadString('\n')
	if err != nil {
		return 0, "", 0, err
	}
	fields := strings.Fields(strings.TrimSpace(line))
	if len(fields) != 4 || fields[0] != "C" {
		return 0, "", 0, errors.New("bad capture request")
	}
	monitor, err = strconv.Atoi(fields[1])
	if err != nil {
		return 0, "", 0, err
	}
	format = fields[2]
	quality, err = strconv.Atoi(fields[3])
	if err != nil {
		return 0, "", 0, err
	}
	return monitor, format, quality, nil
}

func writeFrame(w io.Writer, img models.CapturedImage) error {
	if len(img.Data) > config.MaxCaptureBytes {
		return errors.New("frame too large")
	}
	if _, err := fmt.Fprintf(w, "O %s %d %d %d %d %d\n",
		strings.ReplaceAll(img.ContentType, " ", ""),
		img.Left, img.Top, img.Width, img.Height, len(img.Data)); err != nil {
		return err
	}
	_, err := w.Write(img.Data)
	return err
}

func writeErr(w io.Writer, msg string) error {
	msg = strings.ReplaceAll(strings.TrimSpace(msg), "\n", " ")
	if msg == "" {
		msg = "capture failed"
	}
	_, err := fmt.Fprintf(w, "E %s\n", msg)
	return err
}

func readResponse(r *bufio.Reader) (models.CapturedImage, error) {
	line, err := r.ReadString('\n')
	if err != nil {
		return models.CapturedImage{}, err
	}
	line = strings.TrimRight(line, "\r\n")
	if strings.HasPrefix(line, "E ") {
		return models.CapturedImage{}, errors.New(strings.TrimSpace(line[2:]))
	}
	fields := strings.Fields(line)
	if len(fields) != 7 || fields[0] != "O" {
		return models.CapturedImage{}, errors.New("bad capture response")
	}
	left, _ := strconv.Atoi(fields[2])
	top, _ := strconv.Atoi(fields[3])
	width, _ := strconv.Atoi(fields[4])
	height, _ := strconv.Atoi(fields[5])
	n, err := strconv.Atoi(fields[6])
	if err != nil || n < 0 || n > config.MaxCaptureBytes {
		return models.CapturedImage{}, errors.New("bad capture size")
	}
	data := make([]byte, n)
	if _, err := io.ReadFull(r, data); err != nil {
		return models.CapturedImage{}, err
	}
	return models.CapturedImage{
		ContentType: fields[1],
		Data:        data,
		Left:        left,
		Top:         top,
		Width:       width,
		Height:      height,
	}, nil
}