#include "line-editor.h"

#include <fx/encoding.h>

static void convert_offset_to_xy(
	struct bshell_line_ed_p *ed,
	unsigned long offset,
	unsigned long *out_x,
	unsigned long *out_y)
{
	unsigned long x = 0, y = 0;
	unsigned int w = 0, h = 0;
	fx_tty_get_dimensions(ed->ed_tty, &w, &h);
	if (!w || !h) {
		w = 80;
		h = 25;
	}

	fx_string *prompt = line_ed_get_prompt(ed);
	fx_string *buffer = line_ed_get_buffer(ed);
	const char *s = fx_string_get_cstr(prompt);
	size_t len = fx_string_get_size(prompt, FX_STRLEN_CODEPOINTS);
	fx_wchar prev = FX_WCHAR_INVALID;

	for (unsigned long i = 0; i < len; i++) {
		fx_wchar c = fx_wchar_utf8_codepoint_decode(s);
		if (prev != FX_WCHAR_INVALID) {
			if (prev == '\n' || x + 1 >= w) {
				x = 0;
				y++;
			} else {
				x += line_ed_get_char_width(c);
			}
		}

		unsigned int stride = fx_wchar_utf8_codepoint_size(c);
		if (stride == 0) {
			break;
		}

		s += stride;
		prev = c;
	}

	s = fx_string_get_cstr(buffer);
	len = fx_string_get_size(buffer, FX_STRLEN_CODEPOINTS);
	for (unsigned long i = 0; i < offset && i < len; i++) {
		fx_wchar c = fx_wchar_utf8_codepoint_decode(s);
		if (prev != FX_WCHAR_INVALID) {
			if (prev == '\n' || x + 1 >= w) {
				x = 0;
				y++;
			} else {
				x += line_ed_get_char_width(c);
			}
		}

		unsigned int stride = fx_wchar_utf8_codepoint_size(c);
		if (stride == 0) {
			break;
		}

		s += stride;
		prev = c;
	}

	if (offset > len) {
		if (x + 1 >= w) {
			x = 0;
			y++;
		} else {
			x++;
		}
	}

	if (out_x) {
		*out_x = x;
	}

	if (out_y) {
		*out_y = y;
	}
}

void line_ed_get_points(struct bshell_line_ed_p *ed, struct cursor_points *out)
{
	unsigned long cursor = line_ed_get_cursor(ed);
	fx_string *buffer = line_ed_get_buffer(ed);

	convert_offset_to_xy(
		ed,
		cursor + 1,
		&out->c_cursor_x,
		&out->c_cursor_y);
	convert_offset_to_xy(
		ed,
		fx_string_get_size(buffer, FX_STRLEN_CODEPOINTS),
		&out->c_render_limit_x,
		&out->c_render_limit_y);
	convert_offset_to_xy(
		ed,
		fx_string_get_size(buffer, FX_STRLEN_CODEPOINTS) + 1,
		&out->c_cursor_limit_x,
		&out->c_cursor_limit_y);
}