package app

// terminalLayout is the single source of truth for host chrome and the
// child PTY viewport.
type terminalLayout struct {
	hostCols uint16
	hostRows uint16

	mainLeft uint16
	mainTop  uint16
	mainCols uint16
	mainRows uint16

	sidebarVisible bool
	sidebarLeft    uint16
	sidebarWidth   uint16

	statusRow uint16
}

func newTerminalLayout(cols, rows uint16) terminalLayout {
	if cols == 0 {
		cols = 1
	}
	if rows == 0 {
		rows = 1
	}

	l := terminalLayout{
		hostCols:  cols,
		hostRows:  rows,
		mainLeft:  1,
		mainTop:   tabBarRows + 1,
		mainCols:  cols,
		mainRows:  1,
		statusRow: rows,
	}

	if int(cols) > sidebarCols+10 {
		l.sidebarVisible = true
		l.sidebarWidth = sidebarCols
		l.sidebarLeft = cols - sidebarCols + 1
		// The sidebar's left border lives one column to the left of
		// sidebarLeft. The viewport must stop one column short of that
		// border or child output (and clearViewport ECH) would erase
		// it whenever the cursor reached the right margin.
		l.mainCols = cols - sidebarCols - 1
	}

	reservedRows := tabBarRows + statusRows
	if int(rows) > reservedRows {
		l.mainRows = rows - uint16(reservedRows)
	}
	return l
}

func (l terminalLayout) childCols() uint16 {
	if l.mainCols == 0 {
		return 1
	}
	return l.mainCols
}

func (l terminalLayout) childRows() uint16 {
	if l.mainRows == 0 {
		return 1
	}
	return l.mainRows
}

func ptyRows(hostRows uint16) uint16 {
	return newTerminalLayout(1, hostRows).childRows()
}

func ptyCols(hostCols uint16) uint16 {
	return newTerminalLayout(hostCols, 1).childCols()
}