// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>

package readline

import (
	"fmt"
	"kitty/tools/wcswidth"
)

var _ = fmt.Print

func (self *Readline) write_line_with_prompt(line, prompt string, screen_width int) int {
	self.loop.QueueWriteString(prompt)
	self.loop.QueueWriteString(line)
	w := wcswidth.Stringwidth(prompt) + wcswidth.Stringwidth(line)
	num_lines := w / screen_width
	if w%screen_width == 0 {
		num_lines--
	}
	return num_lines
}

func (self *Readline) move_cursor_to_text_position(pos, screen_width int) int {
	num_of_lines := pos / screen_width
	self.loop.MoveCursorVertically(num_of_lines)
	self.loop.QueueWriteString("\r")
	x := pos % screen_width
	self.loop.MoveCursorHorizontally(x)
	return num_of_lines
}

func (self *Readline) update_current_screen_size() {
	screen_size, err := self.loop.ScreenSize()
	if err != nil {
		screen_size.WidthCells = 80
		screen_size.HeightCells = 24
	}
	if screen_size.WidthCells < 1 {
		screen_size.WidthCells = 1
	}
	if screen_size.HeightCells < 1 {
		screen_size.HeightCells = 1
	}
	self.screen_width = int(screen_size.WidthCells)
}

func (self *Readline) redraw() {
	if self.screen_width == 0 {
		self.update_current_screen_size()
	}
	if self.screen_width < 4 {
		return
	}
	if self.cursor_y > 0 {
		self.loop.MoveCursorVertically(-self.cursor_y)
	}
	self.loop.QueueWriteString("\r")
	self.loop.ClearToEndOfScreen()
	line_with_cursor := 0
	y := 0
	for i, line := range self.lines {
		p := self.prompt
		if i > 0 {
			y += 1
			self.loop.QueueWriteString("\r\n")
			p = self.continuation_prompt
		}
		if i == self.cursor.Y {
			line_with_cursor = y
		}
		y += self.write_line_with_prompt(line, p, self.screen_width)
	}
	self.loop.MoveCursorVertically(-y + line_with_cursor)
	line := self.lines[self.cursor.Y]
	plen := self.prompt_len
	if self.cursor.Y > 0 {
		plen = self.continuation_prompt_len
	}
	line_with_cursor += self.move_cursor_to_text_position(plen+wcswidth.Stringwidth(line[:self.cursor.X]), self.screen_width)
	self.cursor_y = line_with_cursor
}