#include <stdio.h>
#include <stdlib.h>
#include "line-ed.h"
#include "refresh.h"
#include "buffer.h"
#include "cursor.h"
#include "hl-range.h"
#include <blue/term/tty.h>

/* prints the provided string to the terminal, applying any relevant highlight ranges.
 * this function prints all characters in `s` until it encounters a null char (\0) or
 * linefeed (\n).
 *
 * the (x, y) coordinates provided should be the data coordinates of the
 * first character in `s`.
 */
void print_text(struct line_ed *ed, size_t x, size_t y, const char *s)
{
	b_tty *tty = ed->l_tty;
	struct hl_range *cur_range = get_hl_range(ed, x, y);

	for (size_t i = 0; s[i] != '\n' && s[i] != '\0'; i++) {
		if (!cur_range) {
			b_tty_reset_vmode(tty);
			fputc(s[i], stdout);
			continue;
		}

		while (1) {
			if (!cur_range) {
				break;
			}

			int hl_result = apply_hl_range(cur_range, tty, x + i, y);
			if (hl_result == 0) {
				break;
			}

			cur_range = get_next_hl_range(cur_range);
			apply_hl_range(cur_range, tty, x + i, y);
		}

		fputc(s[i], stdout);
	}
}

void print_buffer(struct line_ed *ed)
{
	const char *line_buf = ed->l_buf;
	size_t line_len = strcspn(line_buf, "\n");

	unsigned int y = 0;

	while (1) {
		print_text(ed,0, y, line_buf);

		line_buf += line_len;
		if (*line_buf == '\n') {
			line_buf++;
		}

		if (*line_buf == '\0') {
			break;
		}

		y++;
		line_len = strcspn(line_buf, "\n");

		fputc('\r', stdout);
		fputc('\n', stdout);
	}
}

/* this function is called after a character is inserted into the line_ed buffer.
 * the function performs the following steps:
 *	1. get a pointer to the start of the line that was modified.
 *	2. determine the first character in the line that needs to be redrawn.
 *	   this may result in an append, a partial reprint, or a full reprint.
 *	3. re-print the relevant portion of the buffer:
 *	   for an append (a character added to the end of the line):
 *		* write the inserted char to the terminal.
 *		* done.
 *	   for a partial reprint:
 *		* clear all printed chars from the logical cursor position to the end of the line.
 *		* print the portion of the line corresponding to the cleared section.
 *		* move the physical (terminal) cursor backwards until its position
 *		  matches the logical (line_ed) cursor.
 *	   for a full reprint:
 *		* same as a partial reprint except that, rather than reprinting
 *		  from the logical cursor position, the entire line is reprinted.
 */
void put_refresh(struct line_ed *ed, struct refresh_state *state)
{
	/* get the data for the line that is being refreshed */
	const char *line_buf = line_start(ed, ed->l_cursor_y);
	size_t line_len = strcspn(line_buf, "\n");

	/* the index of the first char in line_buf that needs to be reprinted */
	size_t start_x = state->r_prev_cursor_x;

	/* the distance between the first char to be reprinted and the end
	 * of the line.
	 * the physical cursor will be moved back by this amount after the
	 * line is reprinted. */
	long cursor_rdelta = (long)(line_len - start_x);

	if (ed->l_flags & LINE_ED_FULL_REPRINT) {
		if (start_x) {
			//fprintf(stdout, "\033[%uD", start_x);
			b_tty_move_cursor_x(ed->l_tty, B_TTY_POS_CURSOR, -(long long)start_x);
		}

		start_x = 0;
	}

	print_text(ed, start_x, ed->l_cursor_y, line_buf + start_x);

	/* decrement the rdelta (move the cursor back one fewer cells),
	 * so that the physical cursor will be placed AFTER the character that
	 * was just inserted. */
	cursor_rdelta--;
	b_tty_move_cursor_x(ed->l_tty, B_TTY_POS_CURSOR, -cursor_rdelta);

	#if 0
	for (unsigned int i = 0; i < cursor_rdelta; i++) {
		fputs("\010", stdout);
	}
	#endif

	fflush(stdout);
}

/* this function is called after a character is removed from the line_ed buffer.
 * IF the character was a linefeed.
 *
 * this is separate from backspace_simple_refresh because, in this situation,
 * the cursor position depends on the length of the previous line before
 * the linefeed was deleted, and we have to reprint every line following the
 * two that were combined.
 */
void backspace_nl_refresh(struct line_ed *ed, struct refresh_state *state)
{
	/* get the data for the line that is being refreshed.
	 * relative to where the cursor was before the linefeed was deleted,
	 * this is the PREVIOUS line. */
	const char *line_buf = line_start(ed, ed->l_cursor_y);
	size_t line_len = strcspn(line_buf, "\n");

	/* the index of the first char in line_buf that needs to be reprinted.
	 * subtract one to account for the linefeed that has since been deleted. */
	size_t start_x = state->r_prev_line_len - 1;

	/* the column to move the physical cursor to after it has been moved
	 * to the previous line.
	 * NOTE that this number includes the length of the prompt!
	 * we add 1 to start_x to ensure that the cursor is moved to the cell
	 * AFTER the last char of the line. */
	size_t new_x;
	line_ed_coords_to_physical_coords(ed, start_x + 1, ed->l_cursor_y, &new_x, NULL);

	/* the physical cursor is currently at the beginning of the line that
	 * has just been moved up. from here, clear this line and the rest
	 * from the screen. */
	//fputs("\033[J", stdout);
	b_tty_clear(ed->l_tty, B_TTY_CLEAR_SCREEN | B_TTY_CLEAR_FROM_CURSOR);

	if (ed->l_flags & LINE_ED_FULL_REPRINT) {
		/* next, move the physical cursor up and to the beginning of the previous line */
		size_t tmp_x;
		line_ed_coords_to_physical_coords(ed, 0, ed->l_cursor_y, &tmp_x, NULL);
		b_tty_move_cursor_y(ed->l_tty, B_TTY_POS_CURSOR, -1);
		b_tty_move_cursor_x(ed->l_tty, B_TTY_POS_START, tmp_x);
		//fprintf(stdout, "\033[A\033[%uG", tmp_x + 1);
		start_x = 0;
	} else {
		/* next, move the physical cursor up and to the end of the previous line */
		//fprintf(stdout, "\033[A\033[%uG", new_x);
		b_tty_move_cursor_y(ed->l_tty, B_TTY_POS_CURSOR, -1);
		b_tty_move_cursor_x(ed->l_tty, B_TTY_POS_START, new_x);
	}

	/* now reprint all of the buffer lines, starting with the first of the
	 * two lines that were concatenated. */
	size_t ydiff = 0;
	while (1) {
		print_text(ed, start_x, ed->l_cursor_y + ydiff, line_buf + start_x);

		line_buf += line_len + 1;
		line_len = strcspn(line_buf, "\n");
		start_x = 0;

		if (*line_buf == '\0') {
			break;
		}

		fputc('\r', stdout);
		fputc('\n', stdout);
		ydiff++;
	}

	/* finally, move the cursor BACK to the point where the two lines
	 * were concatenated. */
	if (ydiff) {
		//fprintf(stdout, "\033[%uA", ydiff);
		b_tty_move_cursor_y(ed->l_tty, B_TTY_POS_CURSOR, ydiff);
	}

	//fprintf(stdout, "\033[%uG", new_x);
	b_tty_move_cursor_x(ed->l_tty, B_TTY_POS_START, new_x);
	fflush(stdout);
}

/* this function is called after a character is removed from the line_ed buffer.
 * IF the character was not a linefeed.
 */
void backspace_simple_refresh(struct line_ed *ed, struct refresh_state *state)
{
	/* get the data for the line that is being refreshed */
	const char *line_buf = line_start(ed, ed->l_cursor_y);
	size_t line_len = strcspn(line_buf, "\n");

	/* the index of the first char in line_buf that needs to be reprinted */
	size_t start_x = ed->l_cursor_x;
	//get_data_cursor_position(ed, &start_x, NULL);

	/* the distance between the first char to be reprinted and the end
	 * of the line.
	 * the physical cursor will be moved back by this amount after the
	 * line is reprinted. */
	long long cursor_rdelta = (long long)(line_len - start_x);

	if (ed->l_flags & LINE_ED_FULL_REPRINT) {
		if (start_x) {
			//fprintf(stdout, "\033[%uD", start_x);
			b_tty_move_cursor_x(ed->l_tty, B_TTY_POS_CURSOR, -(long long)start_x);
		}

		start_x = 0;
	}

	//fputc('\010', stdout);
	b_tty_move_cursor_x(ed->l_tty, B_TTY_POS_CURSOR, -1);
	print_text(ed, start_x, ed->l_cursor_y, line_buf + start_x);
	fputc(' ', stdout);

	/* increment the rdelta (move the cursor back one more cell), so
	 * that the cursor will appear to move back one cell (to accord with
	 * the fact that backspace was just pressed) */
	cursor_rdelta++;

	b_tty_move_cursor_x(ed->l_tty, B_TTY_POS_CURSOR, -cursor_rdelta);

	#if 0
	for (unsigned int i = 0; i < cursor_rdelta; i++) {
		fputs("\010", stdout);
	}
	#endif

	fflush(stdout);
}