/* Text widget implementation. */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <ctype.h>
#include <stdlib.h>
#include <string.h>

#include "elinks.h"

#include "bfu/dialog.h"
#include "bfu/text.h"
#include "config/kbdbind.h"
#include "intl/gettext/libintl.h"
#include "terminal/draw.h"
#include "terminal/mouse.h"
#include "terminal/terminal.h"
#include "util/color.h"

/* FIXME: For UTF-8 strings we need better function than isspace. */
#define is_unsplitable(pos) (*(pos) && *(pos) != '\n' && !isspace(*(pos)))

void
add_dlg_text(struct dialog *dlg, unsigned char *text,
	     enum format_align align, int bottom_pad)
{
	struct widget *widget = &dlg->widgets[dlg->number_of_widgets++];

	widget->type = WIDGET_TEXT;
	widget->text = text;

	widget->info.text.align	   = align;
	widget->info.text.is_label = !!bottom_pad;
}

/* Returns length of substring (from start of @text) before a split. */
#ifdef CONFIG_UTF_8
static inline int
split_line(unsigned char *text, int max_width, int *cells, int utf8)
#else
static inline int
split_line(unsigned char *text, int max_width, int *cells)
#endif /* CONFIG_UTF_8 */
{
	unsigned char *split = text;
	int cells_save = *cells;

	if (max_width <= 0) return 0;

	while (*split && *split != '\n') {
		unsigned char *next_split;
#ifdef CONFIG_UTF_8
		if (utf8) {
			unsigned char *next_char_begin = split 
							 + utf8charlen(split);

			next_split = split;

			*cells += utf8_char2cells(split, NULL);
			while (*next_split && next_split != next_char_begin)
				next_split++;

			next_char_begin = next_split;
			while (is_unsplitable(next_split)) 
			{
				if (next_split < next_char_begin) {
					next_split++;
					continue;
				}
				*cells += utf8_char2cells(next_split, NULL);
				next_char_begin += utf8charlen(next_split);
			}
		} else
#endif /* CONFIG_UTF_8 */
		{
			next_split = split + 1;

			while (is_unsplitable(next_split))
				next_split++;
			*cells = next_split - text;
		}

		if (*cells > max_width) {
			/* Force a split if no position was found yet,
			 * meaning there's no splittable substring under
			 * requested width. */
			if (split == text) {
#ifdef CONFIG_UTF_8
				if (utf8) {
					int m_bytes = utf8_cells2bytes(text,
								       max_width,
								       NULL);
					split = &text[m_bytes];
				} else
#endif /* CONFIG_UTF_8 */
					split = &text[max_width];


				/* FIXME: Function ispunct won't work correctly
				 * with UTF-8 characters. We need some similar
				 * function for UTF-8 characters. */
#ifndef CONFIG_UTF_8
				/* Give preference to split on a
				 * punctuation if any. Note that most
				 * of the time punctuation char is
				 * followed by a space so this rule
				 * will not match often. We match dash
				 * and quotes too. */
				cells_save--;
				while (--split != text) {
					cells_save--;
					if (!ispunct(*split)) continue;
					split++;
					cells_save++;
					break;
				}
#endif /* CONFIG_UTF_8 */

				/* If no way to do a clean split, just return
				 * requested maximal width. */
				if (split == text) {
					*cells = max_width;
					return max_width;
				}
			}
			break;
		}

		cells_save = *cells;
		split = next_split;
	}

	*cells = cells_save;
	return split - text;
}

#undef is_unsplitable

#define LINES_GRANULARITY 0x7
#define realloc_lines(x, o, n) mem_align_alloc(x, o, n, LINES_GRANULARITY)

/* Find the start of each line with the current max width */
#ifdef CONFIG_UTF_8
static unsigned char **
split_lines(struct widget_data *widget_data, int max_width, int utf8)
#else
static unsigned char **
split_lines(struct widget_data *widget_data, int max_width)
#endif /* CONFIG_UTF_8 */
{
	unsigned char *text = widget_data->widget->text;
	unsigned char **lines = (unsigned char **) widget_data->cdata;
	int line = 0;

	if (widget_data->info.text.max_width == max_width) return lines;

	/* We want to recalculate the max line width */
	widget_data->box.width = 0;

	while (*text) {
		int width;
		int cells = 0;

		/* Skip first leading \n or space. */
		if (isspace(*text)) text++;
		if (!*text) break;

#ifdef CONFIG_UTF_8
		width = split_line(text, max_width, &cells, utf8);
#else
		width = split_line(text, max_width, &cells);
#endif

		/* split_line() may return 0. */
		if (width < 1) {
			width = 1; /* Infinite loop prevention. */
		}
		if (cells < 1) {
			cells = 1; /* Infinite loop prevention. */
		}

		int_lower_bound(&widget_data->box.width, cells);

		if (!realloc_lines(&lines, line, line + 1))
			break;

		lines[line++] = text;
		text += width;
	}

	/* Yes it might be a bit ugly on the other hand it will be autofreed
	 * for us. */
	widget_data->cdata = (unsigned char *) lines;
	widget_data->info.text.lines = line;
	widget_data->info.text.max_width = max_width;

	return lines;
}

/* Format text according to dialog box and alignment. */
void
dlg_format_text_do(struct terminal *term, unsigned char *text,
		int x, int *y, int width, int *real_width,
		struct color_pair *color, enum format_align align, 
		int format_only)
{
	int line_width;
	int firstline = 1;

	for (; *text; text += line_width, (*y)++) {
		int shift;
		int cells = 0;

		/* Skip first leading \n or space. */
		if (!firstline && isspace(*text))
			text++;
		else
			firstline = 0;
		if (!*text) break;

#ifdef CONFIG_UTF_8
		line_width = split_line(text, width, &cells, term->utf8);
#else
		line_width = split_line(text, width, &cells);
#endif /* CONFIG_UTF_8 */

		/* split_line() may return 0. */
		if (line_width < 1) {
			line_width = 1; /* Infinite loop prevention. */
			continue;
		}

		if (real_width) int_lower_bound(real_width, cells);
		if (format_only || !line_width) continue;

		/* Calculate the number of chars to indent */
		if (align == ALIGN_CENTER)
			shift = (width - cells) / 2;
		else if (align == ALIGN_RIGHT)
			shift = width - cells;
		else
			shift = 0;

		assert(cells <= width && shift < width);

		draw_text(term, x + shift, *y, text, line_width, 0, color);
	}
}

void
dlg_format_text(struct terminal *term, struct widget_data *widget_data,
		int x, int *y, int width, int *real_width, int max_height,
		int format_only)
{
	unsigned char *text = widget_data->widget->text;
	unsigned char saved = 0;
	unsigned char *saved_pos = NULL;
	int height;

	height = int_max(0, max_height - 3);

	/* If we are drawing set up the box before setting up the
	 * scrolling. */
	set_box(&widget_data->box, x, *y,
		widget_data->box.width, height);
	if (height == 0) return;

	/* Can we scroll and do we even have to? */
	if (widget_data->widget->info.text.is_scrollable
	    && (widget_data->info.text.max_width != width
		|| height < widget_data->info.text.lines))
	{
		unsigned char **lines;
		int current;
		int visible;

		/* Ensure that the current split is valid but don't
		 * split if we don't have to */
#ifdef CONFIG_UTF_8
		if (widget_data->box.width != width
		    && !split_lines(widget_data, width, term->utf8))
			return;
#else
		if (widget_data->box.width != width
		    && !split_lines(widget_data, width))
			return;
#endif

		lines = (unsigned char **) widget_data->cdata;

		/* Make maximum number of lines available */
		visible = int_max(widget_data->info.text.lines - height,
				  height);

		int_bounds(&widget_data->info.text.current, 0, visible);
		current = widget_data->info.text.current;

		/* Set the current position */
		text = lines[current];

		/* Do we have to force a text end ? */
		visible = widget_data->info.text.lines - current;
		if (visible > height) {
			int lines_pos = current + height;

			saved_pos = lines[lines_pos];

			/* We save the start of lines so backtrack to see
			 * if the previous line has a line end that should
			 * also be trimmed. */
			if (lines_pos > 0 && saved_pos[-1] == '\n')
				saved_pos--;

			saved = *saved_pos;
			*saved_pos = '\0';
		}

		/* Force dialog to be the width of the longest line */
		if (real_width) int_lower_bound(real_width, widget_data->box.width);

	} else {
		/* Always reset @current if we do not need to scroll */
		widget_data->info.text.current = 0;
	}

	dlg_format_text_do(term, text,
		x, y, width, real_width,
		get_bfu_color(term, "dialog.text"),
		widget_data->widget->info.text.align, format_only);

	if (widget_data->widget->info.text.is_label) (*y)--;

	/* If we scrolled and something was trimmed restore it */
	if (saved && saved_pos) *saved_pos = saved;
}

static widget_handler_status_T
display_text(struct dialog_data *dlg_data, struct widget_data *widget_data)
{
	struct window *win = dlg_data->win;
	struct box box;
	int scale, current, step;
	int lines = widget_data->info.text.lines;

	set_box(&box,
		dlg_data->box.x + dlg_data->box.width - DIALOG_LEFT_BORDER - 1,
		widget_data->box.y,
		1,
		widget_data->box.height);

	if (!text_is_scrollable(widget_data) || box.height <= 0)
		return EVENT_PROCESSED;

	draw_box(win->term, &box, ' ', 0,
		 get_bfu_color(win->term, "dialog.scrollbar"));

	current = widget_data->info.text.current;
	scale = (box.height + 1) * 100 / lines;

	/* Scale the offset of @current */
	step = (current + 1) * scale / 100;
	int_bounds(&step, 0, widget_data->box.height - 1);

	/* Scale the number of visible lines */
	box.height = (box.height + 1) * scale / 100;
	int_bounds(&box.height, 1, int_max(widget_data->box.height - step, 1));

	/* Ensure we always step to the last position too */
	if (lines - widget_data->box.height == current) {
		step = widget_data->box.height - box.height;
	}
	box.y += step;

#ifdef CONFIG_MOUSE
	/* Save infos about selected scrollbar position and size.
	 * We'll use it when handling mouse. */
	widget_data->info.text.scroller_height = box.height;
	widget_data->info.text.scroller_y = box.y;
#endif

	draw_box(win->term, &box, ' ', 0,
		 get_bfu_color(win->term, "dialog.scrollbar-selected"));

	/* Hope this is at least a bit reasonable. Set cursor
	 * and window pointer to start of the first text line. */
	set_cursor(win->term, widget_data->box.x, widget_data->box.y, 1);
	set_window_ptr(win, widget_data->box.x, widget_data->box.y);

	return EVENT_PROCESSED;
}

static void
format_and_display_text(struct widget_data *widget_data,
			struct dialog_data *dlg_data,
			int current)
{
	struct terminal *term = dlg_data->win->term;
	int y = widget_data->box.y;
	int height = dialog_max_height(term);
	int lines = widget_data->info.text.lines;

	assert(lines >= 0);
	assert(widget_data->box.height >= 0);

	int_bounds(&current, 0, lines - widget_data->box.height);

	if (widget_data->info.text.current == current) return;

	widget_data->info.text.current = current;

	draw_box(term, &widget_data->box, ' ', 0,
		 get_bfu_color(term, "dialog.generic"));

	dlg_format_text(term, widget_data,
			widget_data->box.x, &y, widget_data->box.width, NULL,
			height, 0);

	display_text(dlg_data, widget_data);
	redraw_from_window(dlg_data->win);
}

static widget_handler_status_T
kbd_text(struct dialog_data *dlg_data, struct widget_data *widget_data)
{
	int current = widget_data->info.text.current;
	struct term_event *ev = dlg_data->term_event;

	switch (kbd_action(KEYMAP_MENU, ev, NULL)) {
		case ACT_MENU_UP:
			current--;
			break;

		case ACT_MENU_DOWN:
			current++;
			break;

		case ACT_MENU_PAGE_UP:
			current -= widget_data->box.height;
			break;

		case ACT_MENU_PAGE_DOWN:
			current += widget_data->box.height;
			break;

		case ACT_MENU_HOME:
			current = 0;
			break;

		case ACT_MENU_END:
			current = widget_data->info.text.lines;
			break;

		default:
			return EVENT_NOT_PROCESSED;
	}

	format_and_display_text(widget_data, dlg_data, current);

	return EVENT_PROCESSED;
}

static widget_handler_status_T
mouse_text(struct dialog_data *dlg_data, struct widget_data *widget_data)
{
#ifdef CONFIG_MOUSE
	int border = DIALOG_LEFT_BORDER + DIALOG_LEFT_INNER_BORDER;
	int current = widget_data->info.text.current;
	int scroller_y = widget_data->info.text.scroller_y;
	int scroller_height = widget_data->info.text.scroller_height;
	int scroller_middle = scroller_y + scroller_height/2
			      - widget_data->info.text.scroller_last_dir;
	struct box scroller_box;
	struct term_event *ev = dlg_data->term_event;

	set_box(&scroller_box,
		dlg_data->box.x + dlg_data->box.width - 1 - border,
		widget_data->box.y,
		DIALOG_LEFT_INNER_BORDER * 2 + 1,
		widget_data->box.height);

	/* One can scroll by clicking or rolling the wheel on the scrollbar
	 * or one or two cells to its left or its right. */
	if (!check_mouse_position(ev, &scroller_box))
		return EVENT_NOT_PROCESSED;

	switch (get_mouse_button(ev)) {
	case B_LEFT:
		/* Left click scrolls up or down by one step. */
		if (ev->info.mouse.y <= scroller_middle)
			current--;
		else
			current++;
		break;

	case B_RIGHT:
		/* Right click scrolls up or down by more than one step.
		 * Faster. */
		if (ev->info.mouse.y <= scroller_middle)
			current -= 5;
		else
			current += 5;
		break;

	case B_WHEEL_UP:
		/* Mouse wheel up scrolls up. */
		current--;
		break;

	case B_WHEEL_DOWN:
		/* Mouse wheel up scrolls down. */
		current++;
		break;

	default:
		return EVENT_NOT_PROCESSED;
	}

	/* Save last direction used. */
	if (widget_data->info.text.current < current)
		widget_data->info.text.scroller_last_dir = 1;
	else
		widget_data->info.text.scroller_last_dir = -1;

	format_and_display_text(widget_data, dlg_data, current);

#endif /* CONFIG_MOUSE */

	return EVENT_PROCESSED;
}


struct widget_ops text_ops = {
	display_text,
	NULL,
	mouse_text,
	kbd_text,
	NULL,
	NULL,
};