#include "cgit.h"
#include "html.h"
#include "ui-shared.h"

extern int use_ssdiff;

static int current_old_line, current_new_line;

struct deferred_lines {
	int line_no;
	char *line;
	struct deferred_lines *next;
};

static struct deferred_lines *deferred_old, *deferred_old_last;
static struct deferred_lines *deferred_new, *deferred_new_last;

static int line_from_hunk(char *line, char type)
{
	char *buf1, *buf2;
	int len;

	buf1 = strchr(line, type);
	if (buf1 == NULL)
		return 0;
	buf1 += 1;
	buf2 = strchr(buf1, ',');
	if (buf2 == NULL)
		return 0;
	len = buf2 - buf1;
	buf2 = xmalloc(len + 1);
	strncpy(buf2, buf1, len);
	buf2[len] = '\0';
	int res = atoi(buf2);
	free(buf2);
	return res;
}

static char *replace_tabs(char *line)
{
	char *prev_buf = line;
	char *cur_buf;
	int linelen = strlen(line);
	int n_tabs = 0;
	int i;
	char *result;
	char *spaces = "        ";

	if (linelen == 0) {
		result = xmalloc(1);
		result[0] = '\0';
		return result;
	}

	for (i = 0; i < linelen; i++)
		if (line[i] == '\t')
			n_tabs += 1;
	result = xmalloc(linelen + n_tabs * 8 + 1);
	result[0] = '\0';

	while (1) {
		cur_buf = strchr(prev_buf, '\t');
		if (!cur_buf) {
			strcat(result, prev_buf);
			break;
		} else {
			strcat(result, " ");
			strncat(result, spaces, 8 - (strlen(result) % 8));
			strncat(result, prev_buf, cur_buf - prev_buf);
		}
		prev_buf = cur_buf + 1;
	}
	return result;
}

static void deferred_old_add(char *line, int line_no)
{
	struct deferred_lines *item = xmalloc(sizeof(struct deferred_lines));
	item->line = xstrdup(line);
	item->line_no = line_no;
	item->next = NULL;
	if (deferred_old) {
		deferred_old_last->next = item;
		deferred_old_last = item;
	} else {
		deferred_old = deferred_old_last = item;
	}
}

static void deferred_new_add(char *line, int line_no)
{
	struct deferred_lines *item = xmalloc(sizeof(struct deferred_lines));
	item->line = xstrdup(line);
	item->line_no = line_no;
	item->next = NULL;
	if (deferred_new) {
		deferred_new_last->next = item;
		deferred_new_last = item;
	} else {
		deferred_new = deferred_new_last = item;
	}
}

static void print_ssdiff_line(char *class, int old_line_no, char *old_line,
			      int new_line_no, char *new_line)
{
	html("<tr>");
	if (old_line_no > 0)
		htmlf("<td class='lineno'>%d</td><td class='%s'>",
		      old_line_no, class);
	else if (old_line)
		htmlf("<td class='lineno'></td><td class='%s'>", class);
	else
		htmlf("<td class='lineno'></td><td class='%s_dark'>", class);

	if (old_line) {
		old_line = replace_tabs(old_line + 1);
		html_txt(old_line);
		free(old_line);
	}

	html("</td>");

	if (new_line_no > 0)
		htmlf("<td class='lineno'>%d</td><td class='%s'>",
		      new_line_no, class);
	else if (new_line)
		htmlf("<td class='lineno'></td><td class='%s'>", class);
	else
		htmlf("<td class='lineno'></td><td class='%s_dark'>", class);

	if (new_line) {
		new_line = replace_tabs(new_line + 1);
		html_txt(new_line);
		free(new_line);
	}

	html("</td></tr>");
}

static void print_deferred_old_lines()
{
	struct deferred_lines *iter_old, *tmp;

	iter_old = deferred_old;
	while (iter_old) {
		print_ssdiff_line("del", iter_old->line_no,
				  iter_old->line, -1, NULL);
		tmp = iter_old->next;
		free(iter_old);
		iter_old = tmp;
	}
}

static void print_deferred_new_lines()
{
	struct deferred_lines *iter_new, *tmp;

	iter_new = deferred_new;
	while (iter_new) {
		print_ssdiff_line("add", -1, NULL, iter_new->line_no,
				  iter_new->line);
		tmp = iter_new->next;
		free(iter_new);
		iter_new = tmp;
	}
}

static void print_deferred_changed_lines()
{
	struct deferred_lines *iter_old, *iter_new, *tmp;

	iter_old = deferred_old;
	iter_new = deferred_new;
	while (iter_old || iter_new) {
		if (iter_old && iter_new)
			print_ssdiff_line("changed", iter_old->line_no,
					  iter_old->line,
					  iter_new->line_no, iter_new->line);
		else if (iter_old)
			print_ssdiff_line("changed", iter_old->line_no,
					  iter_old->line, -1, NULL);
		else if (iter_new)
			print_ssdiff_line("changed", -1, NULL,
					  iter_new->line_no, iter_new->line);

		if (iter_old) {
			tmp = iter_old->next;
			free(iter_old);
			iter_old = tmp;
		}

		if (iter_new) {
			tmp = iter_new->next;
			free(iter_new);
			iter_new = tmp;
		}
	}
}

void cgit_ssdiff_print_deferred_lines()
{
	if (!deferred_old && !deferred_new)
		return;

	if (deferred_old && !deferred_new)
		print_deferred_old_lines();
	else if (!deferred_old && deferred_new)
		print_deferred_new_lines();
	else
		print_deferred_changed_lines();

	deferred_old = deferred_old_last = NULL;
	deferred_new = deferred_new_last = NULL;
}

/*
 * print a single line returned from xdiff
 */
void cgit_ssdiff_line_cb(char *line, int len)
{
	char c = line[len - 1];

	line[len - 1] = '\0';

	if (line[0] == '@') {
		current_old_line = line_from_hunk(line, '-');
		current_new_line = line_from_hunk(line, '+');
	}

	if (line[0] == ' ') {
		if (deferred_old || deferred_new)
			cgit_ssdiff_print_deferred_lines();
		print_ssdiff_line("ctx", current_old_line, line,
				  current_new_line, line);
		current_old_line += 1;
		current_new_line += 1;
	} else if (line[0] == '+') {
		deferred_new_add(line, current_new_line);
		current_new_line += 1;
	} else if (line[0] == '-') {
		deferred_old_add(line, current_old_line);
		current_old_line += 1;
	} else if (line[0] == '@') {
		html("<tr><td colspan='4' class='hunk'>");
		html_txt(line);
		html("</td></tr>");
	} else {
		html("<tr><td colspan='4' class='ctx'>");
		html_txt(line);
		html("</td></tr>");
	}
	line[len - 1] = c;
}

void cgit_ssdiff_header_begin()
{
	current_old_line = -1;
	current_new_line = -1;
	html("<tr><td class='space' colspan='4'><div></div></td></tr>");
	html("<tr><td class='head' colspan='4'>");
}

void cgit_ssdiff_header_end()
{
	html("</td><tr>");
}

void cgit_ssdiff_footer()
{
	if (deferred_old || deferred_new)
		cgit_ssdiff_print_deferred_lines();
	html("<tr><td class='foot' colspan='4'></td></tr>");
}