package terminal

import (
	"fmt"
	"golang.org/x/term"
	"os"
)

// Screen the size of the screen in rows and columns
type Screen struct {
	Rows int
	Cols int
}

// Size Get the size of the terminal in rows and columns
func Size() *Screen {
	cols := 80
	rows := 24
	var err interface{}

	// Try the syscall first
	cols, rows, err = term.GetSize(int(os.Stdin.Fd()))
	if err == nil {
		return &Screen{rows, cols}
	}

	// Figure out the size the hard way
	if term.IsTerminal(int(os.Stdin.Fd())) {
		rows, cols = sizeTrick()
	}

	return &Screen{rows, cols}
}

func sizeTrick() (rows int, cols int) {
	// Move cursor to location further than likely screen size
	// The cursor will move to maximum available position
	fmt.Print(Code("999C") + Code("999B"))

	// Ask the terminal where the cursor is
	fmt.Print(LocateCursor)

	// Read stdin looking for the reported location
	buffer := ""
	for char, _ := ReadKey(); char != 'R'; char, _ = ReadKey() {

		if char == '\x1b' || char == '[' {
			continue
		}

		if char == 'R' || char == '\x00' {
			break
		}

		buffer += string(char)
	}

	_, err := fmt.Sscanf(buffer, "%d;%d", &rows, &cols)
	if err != nil {
		panic(err)
	}

	return rows, cols
}