/*
 * Copyright (c) 2021 Omar Polo <op@omarpolo.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "compat.h"

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

#include "defaults.h"
#include "telescope.h"
#include "utf8.h"

/*
 * Text wrapping
 * =============
 *
 * There's a simple text wrapping algorithm.
 *
 * 1. if it's a line in a pre-formatted block:
 *    a. hard wrap.
 *    b. repeat
 * 2. otherwise advance the line char by char.
 * 3. when ending the space, split the line at the last occurrence of
 *    a "word separator" (i.e. " \t-") or at point if none.
 * 4. repeat
 *
 */

void
erase_buffer(struct buffer *buffer)
{
	empty_vlist(buffer);
	empty_linelist(buffer);
}

void
empty_linelist(struct buffer *buffer)
{
	struct line *l, *lt;

	TAILQ_FOREACH_SAFE(l, &buffer->page.head, lines, lt) {
		TAILQ_REMOVE(&buffer->page.head, l, lines);
		free(l->line);

		if (l->type != LINE_COMPL &&
		    l->type != LINE_COMPL_CURRENT &&
		    l->type != LINE_HELP)
			free(l->alt);

		free(l);
	}
}

void
empty_vlist(struct buffer *buffer)
{
	struct vline *vl, *t;

	buffer->top_line = NULL;
	buffer->line_off = 0;
	buffer->current_line = NULL;
	buffer->line_max = 0;

	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
		TAILQ_REMOVE(&buffer->head, vl, vlines);
		free(vl->line);
		free(vl);
	}
}

static int
push_line(struct buffer *buffer, struct line *l, const char *buf, size_t len, int flags)
{
	struct vline *vl;
	const char *end;

	/* omit trailing spaces */
	if (len != 0) {
		for (end = buf + len - 1;
		     end > buf && isspace(*end);
		     end--, len--)
			;	/* nop */
	}

	if (!(l->flags & L_HIDDEN))
		buffer->line_max++;

	if ((vl = calloc(1, sizeof(*vl))) == NULL)
		return 0;

	if (len != 0 && (vl->line = calloc(1, len+1)) == NULL) {
		free(vl);
		return 0;
	}

	vl->parent = l;
	if (len != 0)
		memcpy(vl->line, buf, len);
	vl->flags = flags;

	TAILQ_INSERT_TAIL(&buffer->head, vl, vlines);
	return 1;
}

/*
 * Similar to wrap_text, but emit only o vline.
 */
int
wrap_one(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
{
	struct vline *vl, *t;

	/*
	 * be lazy: call wrap_text and then discard the continuations.
	 */

	if (!wrap_text(buffer, prfx, l, width))
		return 0;

	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
		if (vl->flags & L_CONTINUATION) {
			TAILQ_REMOVE(&buffer->head, vl, vlines);
			free(vl->line);
			free(vl);
			buffer->line_max--;
		}
	}

	return 1;
}

/*
 * Build a list of visual line by wrapping the given line, assuming
 * that when printed will have a leading prefix prfx.
 */
int
wrap_text(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
{
	const char	*separators = " \t-";
	const char	*start, *end, *line, *lastsep, *lastchar, *space;
	uint32_t	 cp = 0, state = 0;
	size_t		 cur, prfxwidth, w;
	int		 flags;

	if ((line = l->line) == NULL)
		return push_line(buffer, l, NULL, 0, 0);

	prfxwidth = utf8_swidth(prfx);
	cur = prfxwidth;
	start = line;
	lastsep = NULL;
	lastchar = line;
	flags = 0;

	if (l->type == LINE_LINK && emojify_link &&
	    emojied_line(l->line, &space)) {
		prfxwidth = utf8_swidth_between(l->line, space);
		cur = prfxwidth;
		line = space + 1;
	}

	for (; *line; line++) {
		if (utf8_decode(&state, &cp, *line))
			continue;
		w = utf8_chwidth(cp);
		if (cur + w > width) {
			end = lastsep == NULL
				? utf8_next_cp((char*)lastchar)
				: utf8_next_cp((char*)lastsep);
			if (!push_line(buffer, l, start, end - start, flags))
				return 0;
			flags = L_CONTINUATION;
			start = end;
			cur = prfxwidth + utf8_swidth_between(start, lastchar);
		} else if (strchr(separators, *line) != NULL) {
			lastsep = line;
		}

		lastchar = utf8_prev_cp(line, l->line);
		cur += w;
	}

	return push_line(buffer, l, start, line - start, flags);
}

int
hardwrap_text(struct buffer *buffer, struct line *l, size_t width)
{
	const char	*line, *start, *lastchar;
	int		 cont;
	uint32_t	 state = 0, cp = 0;
	size_t		 cur, w;

	if ((line = l->line) == NULL)
		return push_line(buffer, l, NULL, 0, 0);

	start = line;
	lastchar = line;
	cont = 0;
	cur = 0;
	for (; *line; line++) {
		if (utf8_decode(&state, &cp, *line))
			continue;
		w = utf8_chwidth(cp);
		if (cur + w > width) {
			if (!push_line(buffer, l, start, lastchar-start, cont))
				return 0;
			cont = L_CONTINUATION;
			if (dont_wrap_pre)
				return 1;
			cur = 0;
			start = lastchar;
		}

		lastchar = utf8_prev_cp(line, l->line);
		cur += w;
	}

	return push_line(buffer, l, start, line - start, cont);
}

int
wrap_page(struct buffer *buffer, int width)
{
	struct line		*l;
	const struct line	*top_orig, *orig;
	struct vline		*vl;
	const char		*prfx;

	top_orig = buffer->top_line == NULL ? NULL : buffer->top_line->parent;
	orig = buffer->current_line == NULL ? NULL : buffer->current_line->parent;

	buffer->top_line = NULL;
	buffer->current_line = NULL;

	buffer->force_redraw = 1;
	buffer->curs_y = 0;
	buffer->line_off = 0;

	empty_vlist(buffer);

	TAILQ_FOREACH(l, &buffer->page.head, lines) {
		prfx = line_prefixes[l->type].prfx1;
		switch (l->type) {
		case LINE_TEXT:
		case LINE_LINK:
		case LINE_TITLE_1:
		case LINE_TITLE_2:
		case LINE_TITLE_3:
		case LINE_ITEM:
		case LINE_QUOTE:
		case LINE_PRE_START:
		case LINE_PRE_END:
			wrap_text(buffer, prfx, l, MIN(fill_column, width));
			break;
		case LINE_PRE_CONTENT:
		case LINE_PATCH:
		case LINE_PATCH_HDR:
		case LINE_PATCH_HUNK_HDR:
		case LINE_PATCH_ADD:
		case LINE_PATCH_DEL:
			hardwrap_text(buffer, l, MIN(fill_column, width));
			break;
		case LINE_COMPL:
		case LINE_COMPL_CURRENT:
		case LINE_HELP:
		case LINE_DOWNLOAD:
		case LINE_DOWNLOAD_DONE:
		case LINE_DOWNLOAD_INFO:
			wrap_one(buffer, prfx, l, width);
			break;
		case LINE_FRINGE:
			/* never, ever wrapped */
			break;
		}

		if (top_orig == l && buffer->top_line == NULL) {
			buffer->line_off = buffer->line_max-1;
			buffer->top_line = TAILQ_LAST(&buffer->head, vhead);

			while (1) {
				vl = TAILQ_PREV(buffer->top_line, vhead, vlines);
				if (vl == NULL || vl->parent != orig)
					break;
				buffer->top_line = vl;
				buffer->line_off--;
			}
		}

		if (orig == l && buffer->current_line == NULL) {
			buffer->current_line = TAILQ_LAST(&buffer->head, vhead);

			while (1) {
				vl = TAILQ_PREV(buffer->current_line, vhead, vlines);
				if (vl == NULL || vl->parent != orig)
					break;
				buffer->current_line = vl;
			}
		}
	}

	if (buffer->current_line == NULL)
		buffer->current_line = TAILQ_FIRST(&buffer->head);

	if (buffer->top_line == NULL)
		buffer->top_line = buffer->current_line;

	return 1;
}