/*
 * The output every cgit page has in common. A link from one page to another is
 * built here because only this file knows whether a site addresses a request
 * as a path below a virtual root or as a query string, and the two are spelled
 * differently down to the separator between arguments. The headers, the
 * document head, the header block, the footer, the error page and the age
 * column are here so that a page handler is left with only its own body to
 * produce.
 */

#define USE_THE_REPOSITORY_VARIABLE

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

#define DEFAULT_HTTP_PORT 80

#define SHORT_HASH_LEN 10

// A max-msg-len below this leaves too little of a commit subject to be worth
// truncating, and the ellipsis is paid for out of that same budget.
#define MIN_TRUNCATE_LEN 15
#define ELLIPSIS_LEN 3

// Lines of context git itself defaults to, which a link has no reason to name.
#define DEFAULT_DIFF_CONTEXT 3

// Bounds the breadcrumbs, so that one request cannot turn into an unbounded
// row of links.
#define MAX_CRUMB_LEVELS 15

// cgit_fmt exits the request rather than truncate, so a path is only worked
// into a tab title while it still leaves room to spare in that buffer.
#define MAX_TITLE_PATH_LEN 256

static const char *repo_basename(const char *reponame)
{
	// The result lives in a static buffer, so it is only good until the
	// next call.
	static char buf[1024];
	const char *slash;
	size_t len;
	int last;

	len = strlcpy(buf, reponame, sizeof(buf));
	if (len >= sizeof(buf))
		die("repo_basename: truncated repository name '%s'", reponame);
	last = len - 1;
	while (last && buf[last] == '/')
		buf[last--] = '\0';
	if (last >= 3 && starts_with(&buf[last - 3], ".git")) {
		last -= 3;
		buf[last--] = '\0';
	}
	while (last && buf[last] == '/')
		buf[last--] = '\0';
	slash = strrchr(buf, '/');
	if (slash)
		return ++slash;
	return buf;
}

static const char *root_url(void)
{
	if (ctx.cfg.virtual_root)
		return ctx.cfg.virtual_root;
	else
		return ctx.cfg.script_name;
}

static void site_url(const char *page, const char *search, const char *sort,
		     int ofs, int always_root)
{
	const char *delim = "?";

	if (always_root || page)
		html_attr(root_url());
	else {
		char *currenturl = cgit_currenturl();
		html_attr(currenturl);
		free(currenturl);
	}

	if (page) {
		htmlf("?p=%s", page);
		delim = "&";
	}
	if (search) {
		html(delim);
		html("q=");
		html_url_arg(search);
		delim = "&";
	}
	if (sort) {
		html(delim);
		html("s=");
		html_url_arg(sort);
		delim = "&";
	}
	if (ofs) {
		html(delim);
		htmlf("ofs=%d", ofs);
	}
}

static void site_link(const char *page, const char *name, const char *title,
		      const char *class, const char *search, const char *sort,
		      int ofs, int always_root)
{
	html("<a");
	if (title) {
		html(" title='");
		html_attr(title);
		html("'");
	}
	if (class) {
		html(" class='");
		html_attr(class);
		html("'");
	}
	html(" href='");
	site_url(page, search, sort, ofs, always_root);
	html("'>");
	html_txt(name);
	html("</a>");
}

/*
 * Open an anchor and write the part of its href naming the repository, the
 * page and the path, leaving the href quote open for the caller to add its own
 * arguments and close. The return is the delimiter to put before the first of
 * those, which is still a question mark unless a query string has been opened.
 */
static const char *repolink(const char *title, const char *class,
			    const char *page, const char *head,
			    const char *path)
{
	const char *delim = "?";

	html("<a");
	if (title) {
		html(" title='");
		html_attr(title);
		html("'");
	}
	if (class) {
		html(" class='");
		html_attr(class);
		html("'");
	}
	html(" href='");
	if (ctx.cfg.virtual_root) {
		html_url_path(ctx.cfg.virtual_root);
		html_url_path(ctx.repo->url);
		if (ctx.repo->url[strlen(ctx.repo->url) - 1] != '/')
			html("/");
		if (page) {
			html_url_path(page);
			html("/");
			if (path)
				html_url_path(path);
		}
	} else {
		html_url_path(ctx.cfg.script_name);
		html("?url=");
		html_url_arg(ctx.repo->url);
		if (ctx.repo->url[strlen(ctx.repo->url) - 1] != '/')
			html("/");
		if (page) {
			html_url_arg(page);
			html("/");
			if (path)
				html_url_arg(path);
		}
		delim = "&amp;";
	}
	if (head && ctx.repo->defbranch && strcmp(head, ctx.repo->defbranch)) {
		html(delim);
		html("h=");
		html_url_arg(head);
		delim = "&amp;";
	}
	return cgit_fmt("%s", delim);
}

static const char *emit_rev_arg(const char *delim, const char *rev)
{
	if (rev && ctx.qry.head && strcmp(rev, ctx.qry.head)) {
		html(delim);
		html("id=");
		html_url_arg(rev);
		return "&amp;";
	}
	return delim;
}

static void reporevlink(const char *page, const char *name, const char *title,
			const char *class, const char *head, const char *rev,
			const char *path)
{
	const char *delim;

	delim = repolink(title, class, page, head, path);
	emit_rev_arg(delim, rev);
	html("'>");
	html_txt(name);
	html("</a>");
}

static void emit_diff_args(const char *delim)
{
	if (ctx.qry.difftype) {
		html(delim);
		htmlf("dt=%d", ctx.qry.difftype);
		delim = "&amp;";
	}
	if (ctx.qry.context > 0 && ctx.qry.context != DEFAULT_DIFF_CONTEXT) {
		html(delim);
		html("context=");
		htmlf("%d", ctx.qry.context);
		delim = "&amp;";
	}
	if (ctx.qry.ignorews) {
		html(delim);
		html("ignorews=1");
		delim = "&amp;";
	}
	if (ctx.qry.follow) {
		html(delim);
		html("follow=1");
	}
}

static struct string_list_item *lookup_path(struct string_list *list,
					    const char *path)
{
	struct string_list_item *item;

	while (path && path[0]) {
		if ((item = string_list_lookup(list, path)))
			return item;
		if (!(path = strchr(path, '/')))
			break;
		path++;
	}
	return NULL;
}

/*
 * A repository can supply the module-link template through a repo-local
 * cgitrc, so the %s placeholders are expanded here instead of the template
 * being handed to printf, where a surplus conversion would read past the
 * argument list.
 */
static void emit_module_link(const char *tmpl, const char **args, int nargs)
{
	struct strbuf sb = STRBUF_INIT;
	int used = 0;

	while (*tmpl) {
		if (*tmpl != '%') {
			strbuf_addch(&sb, *tmpl++);
			continue;
		}
		tmpl++;
		if (*tmpl == '%') {
			strbuf_addch(&sb, '%');
			tmpl++;
		} else if (*tmpl == 's' && used < nargs) {
			strbuf_addstr(&sb, args[used++]);
			tmpl++;
		} else {
			strbuf_addch(&sb, '%');
		}
	}
	html_attr(sb.buf);
	strbuf_release(&sb);
}

static struct date_mode configured_date_mode(void)
{
	struct date_mode mode = ctx.cfg.date_mode;

	if (ctx.cfg.local_time)
		mode.local = 1;
	return mode;
}

/*
 * Dates render as time elements, whose datetime attribute wants the strict
 * ISO 8601 form with the T separator rather than the space git prints by
 * default.
 */
static void print_abs_date(time_t t, int tz)
{
	html("<time datetime='");
	html_attr(show_date(t, tz, cgit_date_mode(DATE_ISO8601_STRICT)));
	html("' title='");
	html_attr(show_date(t, tz, cgit_date_mode(DATE_ISO8601)));
	html("'>");
	html_txt(show_date(t, tz, configured_date_mode()));
	html("</span>");
}

static void print_rel_date(time_t t, int tz, double count, const char *class,
			   const char *suffix)
{
	htmlf("<time class='%s' datetime='", class);
	html_attr(show_date(t, tz, cgit_date_mode(DATE_ISO8601_STRICT)));
	htmlf("' data-ut='%" PRIu64 "' title='", (uint64_t)t);
	html_attr(show_date(t, tz, cgit_date_mode(DATE_ISO8601)));
	htmlf("'>%.0f %s</time>", count, suffix);
}

static char *http_date(time_t t)
{
	static char day[][4] =
		{"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
	static char month[][4] =
		{"Jan", "Feb", "Mar", "Apr", "May", "Jun",
		 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
	struct tm tm;
	gmtime_r(&t, &tm);
	return cgit_fmt("%s, %02d %s %04d %02d:%02d:%02d GMT", day[tm.tm_wday],
		   tm.tm_mday, month[tm.tm_mon], 1900 + tm.tm_year,
		   tm.tm_hour, tm.tm_min, tm.tm_sec);
}

static void print_rel_vcs_link(const char *url)
{
	html("<link rel='vcs-git' href='");
	html_attr(url);
	html("' title='");
	html_attr(ctx.repo->name);
	html(" Git repository'>\n");
}

static int emit_css_link(struct string_list_item *item, void *fallback)
{
	// An empty css entry is how a site turns the stylesheet off.
	if (item && *item->string == '\0')
		return 0;

	html("<link rel='stylesheet' href='");
	if (item)
		html_attr(item->string);
	else
		html_attr((const char *)fallback);
	html("'/>\n");

	return 0;
}

static int emit_js_link(struct string_list_item *item, void *fallback)
{
	// An empty js entry is how a site turns the script off.
	if (item && *item->string == '\0')
		return 0;

	html("<script src='");
	if (item)
		html_attr(item->string);
	else
		html_attr((const char *)fallback);
	html("'></script>\n");

	return 0;
}

static void add_clone_urls(void (*fn)(const char *), char *urls, char *suffix)
{
	struct strbuf **url_list = strbuf_split_str(urls, ' ', 0);
	int i;

	for (i = 0; url_list[i]; i++) {
		strbuf_rtrim(url_list[i]);
		if (url_list[i]->len == 0)
			continue;
		if (suffix && *suffix)
			strbuf_addf(url_list[i], "/%s", suffix);
		fn(url_list[i]->buf);
	}

	strbuf_list_free(url_list);
}

static int print_branch_option(const struct reference *ref, void *counter)
{
	int *count = counter;
	const char *name = ref->name;
	// The switcher runs on every page, so it is bounded like the refs list.
	if (ctx.cfg.max_ref_count && *count >= ctx.cfg.max_ref_count)
		return -1;
	(*count)++;
	html_option(name, name, ctx.qry.head);
	return 0;
}

static void print_header(void)
{
	const char *logo = NULL, *logo_link = NULL;

	if (ctx.repo && ctx.repo->logo && *ctx.repo->logo)
		logo = ctx.repo->logo;
	else
		logo = ctx.cfg.logo;
	if (ctx.repo && ctx.repo->logo_link && *ctx.repo->logo_link)
		logo_link = ctx.repo->logo_link;
	else
		logo_link = ctx.cfg.logo_link;

	html("<header id='header'>\n");
	if (logo && *logo) {
		html("<a class='logo' href='");
		if (logo_link && *logo_link)
			html_attr(logo_link);
		else
			html_attr(root_url());
		html("'><img src='");
		html_attr(logo);
		html("' alt='cgit logo'></a>\n");
	}

	html("<h1 class='main'>");
	if (ctx.repo) {
		cgit_index_link("index", NULL, NULL, NULL, NULL, 0, 1);
		html(" : ");
		cgit_summary_link(ctx.repo->name, NULL, NULL, NULL);
	} else
		html_txt(ctx.cfg.root_title);
	html("</h1>\n");

	// A repository with no commits has no branches to list, so the
	// switcher would be an empty select next to a switch button.
	if (ctx.repo && ctx.env.authenticated && !ctx.empty_repo) {
		html("<form class='branch-switch' method='get'>\n");
		cgit_add_hidden_formfields(0, 1, ctx.qry.page);
		html("<select name='h' aria-label='Branch' data-autosubmit='1'>\n");
		int branch_count = 0;
		refs_for_each_branch_ref(get_main_ref_store(the_repository),
					 print_branch_option, &branch_count);
		if (ctx.repo->enable_remote_branches)
			refs_for_each_remote_ref(get_main_ref_store(the_repository),
						 print_branch_option, &branch_count);
		html("</select> ");
		html("<input type='submit' value='switch'>");
		html("</form>\n");
	}

	if (ctx.repo) {
		html("<p class='sub desc'>");
		html_txt(ctx.repo->desc);
		html("</p>\n");
		html("<p class='sub owner'>");
		html_txt(ctx.repo->owner);
		html("</p>\n");
	} else if (ctx.cfg.root_desc) {
		html("<p class='sub desc'>");
		html_txt(ctx.cfg.root_desc);
		html("</p>\n");
	}

	html("<button type='button' class='theme-toggle' hidden "
	     "aria-label='Toggle color theme'></button>\n");
	html("</header>\n");
}

static const char *tab_class(const char *page)
{
	if (!ctx.qry.page)
		return NULL;

	return strcmp(ctx.qry.page, page) ? NULL : "active";
}

static const char *tab_title(const char *format, const char *fallback,
			     const char *path)
{
	if (!path || !*path || strlen(path) > MAX_TITLE_PATH_LEN)
		return fallback;
	return cgit_fmt(format, path);
}

static void print_repo_tabs(void)
{
	const char *vpath = ctx.qry.vpath;

	html("<ul>\n");
	if (ctx.repo->readme.nr) {
		html("<li>");
		reporevlink("about", "about", "About this repository",
			    tab_class("about"), ctx.qry.head, NULL, NULL);
		html("</li>\n");
	}
	html("<li>");
	cgit_summary_link("summary", "Repository summary", tab_class("summary"),
			  ctx.qry.head);
	html("</li>\n<li>");
	cgit_refs_link("refs", "Branches and tags", tab_class("refs"),
		       ctx.qry.head, ctx.qry.oid, NULL);
	html("</li>\n<li>");
	cgit_log_link("log",
		      tab_title("Commit history of %s", "Commit history", vpath),
		      tab_class("log"), ctx.qry.head,
		      NULL, ctx.qry.vpath, 0, NULL, NULL,
		      ctx.qry.showmsg, ctx.qry.follow);
	html("</li>\n<li>");
	if (ctx.qry.page && !strcmp(ctx.qry.page, "blame"))
		cgit_blame_link("blame",
				tab_title("Line-by-line blame of %s", "Blame", vpath),
				tab_class("blame"), ctx.qry.head,
				ctx.qry.oid, ctx.qry.vpath);
	else
		cgit_tree_link("tree",
			       tab_title("Browse the tree at %s", "Browse the file tree", vpath),
			       tab_class("tree"), ctx.qry.head,
			       ctx.qry.oid, ctx.qry.vpath);
	html("</li>\n<li>");
	cgit_commit_link("commit", "The current commit", tab_class("commit"),
			 ctx.qry.head, ctx.qry.oid, ctx.qry.vpath);
	html("</li>\n<li>");
	cgit_diff_link("diff",
		       tab_title("Changes to %s", "Changes in the current commit", vpath),
		       tab_class("diff"), ctx.qry.head,
		       ctx.qry.oid, ctx.qry.oid2, ctx.qry.vpath);
	html("</li>\n");
	if (ctx.repo->enable_stats) {
		html("<li>");
		cgit_stats_link("stats", "Commit activity", tab_class("stats"),
				ctx.qry.head, ctx.qry.vpath);
		html("</li>\n");
	}
	html("</ul>\n");
}

static void print_repo_search(void)
{
	html("<form class='search' method='get' action='");
	if (ctx.cfg.virtual_root) {
		char *fileurl = cgit_fileurl(ctx.qry.repo, "log",
					     ctx.qry.vpath, NULL);
		html_url_path(fileurl);
		free(fileurl);
	}
	html("'>\n");
	cgit_add_hidden_formfields(1, 0, "log");
	html("<select name='qt' aria-label='Search type'>\n");
	html_option("grep", "log msg", ctx.qry.grep);
	html_option("author", "author", ctx.qry.grep);
	html_option("committer", "committer", ctx.qry.grep);
	html_option("range", "range", ctx.qry.grep);
	html("</select>\n");
	html("<input class='txt' type='search' name='q' aria-label='Search' value='");
	html_attr(ctx.qry.search);
	html("'>\n");
	html("<input type='submit' value='search'>\n");
	html("</form>\n");
}

static void print_site_tabs(void)
{
	html("<ul>\n<li>");
	site_link(NULL, "index", "Repository index", tab_class("repolist"),
		  NULL, NULL, 0, 1);
	html("</li>\n");
	if (ctx.cfg.root_readme) {
		html("<li>");
		site_link("about", "about", "About this site",
			  tab_class("about"), NULL, NULL, 0, 1);
		html("</li>\n");
	}
	html("</ul>\n");
}

static void print_site_search(void)
{
	char *currenturl = cgit_currenturl();

	html("<form class='search' method='get' action='");
	html_attr(currenturl);
	html("'>\n");
	html("<input class='txt' type='search' name='q' aria-label='Search' value='");
	html_attr(ctx.qry.search);
	html("'>\n");
	html("<input type='submit' value='search'>\n");
	html("</form>\n");
	free(currenturl);
}

// The link is built out of the request in ctx.qry, so a caller that alters a
// field of ctx.qry first gets a link differing in exactly that.
static void snapshot_link(const char *name, const char *title, const char *class,
			const char *head, const char *rev,
			const char *archivename)
{
	reporevlink("snapshot", name, title, class, head, rev, archivename);
}

static void self_link(const char *name, const char *title, const char *class)
{
	if (!strcmp(ctx.qry.page, "repolist"))
		cgit_index_link(name, title, class, ctx.qry.search, ctx.qry.sort,
				ctx.qry.ofs, 1);
	else if (!strcmp(ctx.qry.page, "summary"))
		cgit_summary_link(name, title, class, ctx.qry.head);
	else if (!strcmp(ctx.qry.page, "tag"))
		cgit_tag_link(name, title, class, ctx.qry.has_oid ?
			       ctx.qry.oid : ctx.qry.head);
	else if (!strcmp(ctx.qry.page, "tree"))
		cgit_tree_link(name, title, class, ctx.qry.head,
			       ctx.qry.has_oid ? ctx.qry.oid : NULL,
			       ctx.qry.path);
	else if (!strcmp(ctx.qry.page, "plain"))
		cgit_plain_link(name, title, class, ctx.qry.head,
				ctx.qry.has_oid ? ctx.qry.oid : NULL,
				ctx.qry.path);
	else if (!strcmp(ctx.qry.page, "blame"))
		cgit_blame_link(name, title, class, ctx.qry.head,
				ctx.qry.has_oid ? ctx.qry.oid : NULL,
				ctx.qry.path);
	else if (!strcmp(ctx.qry.page, "log"))
		cgit_log_link(name, title, class, ctx.qry.head,
			      ctx.qry.has_oid ? ctx.qry.oid : NULL,
			      ctx.qry.path, ctx.qry.ofs,
			      ctx.qry.grep, ctx.qry.search,
			      ctx.qry.showmsg, ctx.qry.follow);
	else if (!strcmp(ctx.qry.page, "commit"))
		cgit_commit_link(name, title, class, ctx.qry.head,
				 ctx.qry.has_oid ? ctx.qry.oid : NULL,
				 ctx.qry.path);
	else if (!strcmp(ctx.qry.page, "patch"))
		cgit_patch_link(name, title, class, ctx.qry.head,
				ctx.qry.has_oid ? ctx.qry.oid : NULL,
				ctx.qry.path);
	else if (!strcmp(ctx.qry.page, "refs"))
		cgit_refs_link(name, title, class, ctx.qry.head,
			       ctx.qry.has_oid ? ctx.qry.oid : NULL,
			       ctx.qry.path);
	else if (!strcmp(ctx.qry.page, "snapshot"))
		snapshot_link(name, title, class, ctx.qry.head,
				   ctx.qry.has_oid ? ctx.qry.oid : NULL,
				   ctx.qry.path);
	else if (!strcmp(ctx.qry.page, "diff"))
		cgit_diff_link(name, title, class, ctx.qry.head,
			       ctx.qry.oid, ctx.qry.oid2,
			       ctx.qry.path);
	else if (!strcmp(ctx.qry.page, "stats"))
		cgit_stats_link(name, title, class, ctx.qry.head,
				ctx.qry.path);
	else {
		repolink(title, class, ctx.qry.page, ctx.qry.head, ctx.qry.path);
		html("><!-- cgit_self_link() doesn't know how to make link for page '");
		html_txt(ctx.qry.page);
		html("' -->");
		html_txt(name);
		html("</a>");
	}
}

static void print_path_crumbs(char *path)
{
	char *old_path = ctx.qry.path;
	char *start = path, *slash, *end = path + strlen(path);
	int levels = 0;

	ctx.qry.path = NULL;
	self_link("root", NULL, NULL);
	// self_link reads the path out of ctx.qry, so terminating the buffer at
	// each slash is what makes a crumb link to the prefix it stands for.
	ctx.qry.path = start = path;
	while (start < end) {
		if (!(slash = strchr(start, '/')) || levels > MAX_CRUMB_LEVELS)
			slash = end;
		*slash = '\0';
		html_txt("/");
		self_link(start, NULL, NULL);
		if (slash < end)
			*slash = '/';
		start = slash + 1;
		++levels;
	}
	ctx.qry.path = old_path;
}

// A reverse memchr, which glibc has as memrchr but macOS and the BSDs do not.
static const char *find_last_char(const char *start, const char *end, int c)
{
	while (end > start) {
		if (*--end == c)
			return end;
	}
	return NULL;
}

static void vprint_error(const char *fmt, va_list ap)
{
	va_list cp;
	html("<div class='error'>");
	va_copy(cp, ap);
	html_vtxtf(fmt, cp);
	va_end(cp);
	html("</div>\n");
}

void cgit_print_error(const char *fmt, ...)
{
	va_list ap;
	va_start(ap, fmt);
	vprint_error(fmt, ap);
	va_end(ap);
}

const char *cgit_httpscheme(void)
{
	if (ctx.env.https && !strcmp(ctx.env.https, "on"))
		return "https://";
	else
		return "http://";
}

char *cgit_hosturl(void)
{
	if (ctx.env.http_host)
		return xstrdup(ctx.env.http_host);
	if (!ctx.env.server_name)
		return NULL;
	if (!ctx.env.server_port ||
	    atoi(ctx.env.server_port) == DEFAULT_HTTP_PORT)
		return xstrdup(ctx.env.server_name);
	return cgit_fmtalloc("%s:%s", ctx.env.server_name, ctx.env.server_port);
}

char *cgit_currenturl(void)
{
	const char *root = root_url();

	if (!ctx.qry.url)
		return xstrdup(root);
	if (root[0] && root[strlen(root) - 1] == '/')
		return cgit_fmtalloc("%s%s", root, ctx.qry.url);
	return cgit_fmtalloc("%s/%s", root, ctx.qry.url);
}

char *cgit_currentfullurl(void)
{
	const char *root = root_url();
	const char *orig_query = ctx.env.query_string ? ctx.env.query_string : "";
	size_t len = strlen(orig_query);
	char *query = xmalloc(len + 2);
	char *match, *ret;

	// The url argument carried the path into this request and the path is
	// spelled out again below, so it is dropped here. The copy keeps a
	// leading question mark so that every match has a character before it,
	// which is what tells the argument itself from the tail of another one.
	memcpy(query + 1, orig_query, len + 1);
	query[0] = '?';
	match = query;
	while ((match = strstr(match, "url=")) != NULL) {
		if (match[-1] == '?' || match[-1] == '&') {
			const char *next = strchr(match, '&');
			if (next)
				memmove(match, next + 1, strlen(next));
			else
				match[0] = '\0';
		} else
			++match;
	}
	if (!query[1])
		query[0] = '\0';

	if (!ctx.qry.url)
		ret = cgit_fmtalloc("%s%s", root, query);
	else if (root[0] && root[strlen(root) - 1] == '/')
		ret = cgit_fmtalloc("%s%s%s", root, ctx.qry.url, query);
	else
		ret = cgit_fmtalloc("%s/%s%s", root, ctx.qry.url, query);
	free(query);
	return ret;
}

const char *cgit_loginurl(void)
{
	static const char *login_url;
	if (!login_url)
		login_url = cgit_fmtalloc("%s?p=login", root_url());
	return login_url;
}

char *cgit_repourl(const char *reponame)
{
	if (ctx.cfg.virtual_root)
		return cgit_fmtalloc("%s%s/", ctx.cfg.virtual_root, reponame);
	else
		return cgit_fmtalloc("?r=%s", reponame);
}

char *cgit_fileurl(const char *reponame, const char *pagename,
		   const char *filename, const char *query)
{
	struct strbuf sb = STRBUF_INIT;
	const char *delim;

	// The result is a raw URL, so the query joiner is a bare ampersand
	// and each sink escapes the whole string for wherever it lands.
	if (ctx.cfg.virtual_root) {
		strbuf_addf(&sb, "%s%s/%s/%s", ctx.cfg.virtual_root, reponame,
			    pagename, (filename ? filename:""));
		delim = "?";
	} else {
		strbuf_addf(&sb, "?url=%s/%s/%s", reponame, pagename,
			    (filename ? filename : ""));
		delim = "&";
	}
	if (query)
		strbuf_addf(&sb, "%s%s", delim, query);
	return strbuf_detach(&sb, NULL);
}

char *cgit_pageurl(const char *reponame, const char *pagename,
		   const char *query)
{
	return cgit_fileurl(reponame, pagename, NULL, query);
}

const char *cgit_snapshot_prefix(const struct cgit_repo *repo)
{
	if (repo->snapshot_prefix)
		return repo->snapshot_prefix;

	return repo_basename(repo->url);
}

void cgit_index_link(const char *name, const char *title, const char *class,
		     const char *pattern, const char *sort, int ofs,
		     int always_root)
{
	site_link(NULL, name, title, class, pattern, sort, ofs, always_root);
}

void cgit_summary_link(const char *name, const char *title, const char *class,
		       const char *head)
{
	reporevlink(NULL, name, title, class, head, NULL, NULL);
}

void cgit_tag_link(const char *name, const char *title, const char *class,
		   const char *tag)
{
	reporevlink("tag", name, title, class, tag, NULL, NULL);
}

void cgit_tree_link(const char *name, const char *title, const char *class,
		    const char *head, const char *rev, const char *path)
{
	reporevlink("tree", name, title, class, head, rev, path);
}

void cgit_plain_link(const char *name, const char *title, const char *class,
		     const char *head, const char *rev, const char *path)
{
	reporevlink("plain", name, title, class, head, rev, path);
}

void cgit_blame_link(const char *name, const char *title, const char *class,
		     const char *head, const char *rev, const char *path)
{
	reporevlink("blame", name, title, class, head, rev, path);
}

void cgit_log_link(const char *name, const char *title, const char *class,
		   const char *head, const char *rev, const char *path,
		   int ofs, const char *grep, const char *pattern, int showmsg,
		   int follow)
{
	const char *delim;

	delim = repolink(title, class, "log", head, path);
	delim = emit_rev_arg(delim, rev);
	if (grep && pattern) {
		html(delim);
		html("qt=");
		html_url_arg(grep);
		delim = "&amp;";
		html(delim);
		html("q=");
		html_url_arg(pattern);
	}
	if (ofs > 0) {
		html(delim);
		html("ofs=");
		htmlf("%d", ofs);
		delim = "&amp;";
	}
	if (showmsg) {
		html(delim);
		html("showmsg=1");
		delim = "&amp;";
	}
	if (follow) {
		html(delim);
		html("follow=1");
	}
	html("'>");
	html_txt(name);
	html("</a>");
}

void cgit_commit_link(const char *name, const char *title, const char *class,
		      const char *head, const char *rev, const char *path)
{
	const char *delim;

	delim = repolink(title, class, "commit", head, path);
	delim = emit_rev_arg(delim, rev);
	emit_diff_args(delim);
	html("'>");
	if (name && name[0] != '\0') {
		if (ctx.cfg.max_msg_len >= MIN_TRUNCATE_LEN &&
		    strlen(name) > (size_t)ctx.cfg.max_msg_len) {
			html_ntxt(name, ctx.cfg.max_msg_len - ELLIPSIS_LEN);
			html("...");
		} else
			html_txt(name);
	} else
		html_txt("(no commit message)");
	html("</a>");
}

void cgit_refs_link(const char *name, const char *title, const char *class,
		    const char *head, const char *rev, const char *path)
{
	reporevlink("refs", name, title, class, head, rev, path);
}

void cgit_diff_link(const char *name, const char *title, const char *class,
		    const char *head, const char *new_rev, const char *old_rev,
		    const char *path)
{
	const char *delim;

	delim = repolink(title, class, "diff", head, path);
	delim = emit_rev_arg(delim, new_rev);
	if (old_rev) {
		html(delim);
		html("id2=");
		html_url_arg(old_rev);
		delim = "&amp;";
	}
	emit_diff_args(delim);
	html("'>");
	html_txt(name);
	html("</a>");
}

void cgit_patch_link(const char *name, const char *title, const char *class,
		     const char *head, const char *rev, const char *path)
{
	reporevlink("patch", name, title, class, head, rev, path);
}

void cgit_stats_link(const char *name, const char *title, const char *class,
		     const char *head, const char *path)
{
	reporevlink("stats", name, title, class, head, NULL, path);
}

void cgit_object_link(struct object *obj)
{
	const char *page;
	char *shortrev, *fullrev, *name;

	fullrev = oid_to_hex(&obj->oid);
	shortrev = xstrdup(fullrev);
	shortrev[SHORT_HASH_LEN] = '\0';
	if (obj->type == OBJ_COMMIT) {
		cgit_commit_link(cgit_fmt("commit %s...", shortrev), NULL, NULL,
				 ctx.qry.head, fullrev, NULL);
		return;
	} else if (obj->type == OBJ_TREE)
		page = "tree";
	else if (obj->type == OBJ_TAG)
		page = "tag";
	else
		page = "blob";
	name = cgit_fmt("%s %s...", type_name(obj->type), shortrev);
	reporevlink(page, name, NULL, NULL, ctx.qry.head, fullrev, NULL);
}

void cgit_submodule_link(const char *class, char *path, const char *rev)
{
	struct string_list *list;
	struct string_list_item *item;
	char tail, *dir;
	size_t len;

	len = 0;
	tail = 0;
	list = &ctx.repo->submodules;
	item = lookup_path(list, path);
	if (!item) {
		len = strlen(path);
		tail = path[len - 1];
		if (tail == '/') {
			path[len - 1] = 0;
			item = lookup_path(list, path);
		}
	}
	if (item || ctx.repo->module_link) {
		html("<a ");
		if (class)
			htmlf("class='%s' ", class);
		html("href='");
		if (item) {
			const char *args[] = { rev };
			emit_module_link(item->util, args, 1);
		} else {
			const char *args[2];
			dir = strrchr(path, '/');
			if (dir)
				dir++;
			else
				dir = path;
			args[0] = dir;
			args[1] = rev;
			emit_module_link(ctx.repo->module_link, args, 2);
		}
		html("'>");
		html_txt(path);
		html("</a>");
	} else {
		html("<span");
		if (class)
			htmlf(" class='%s'", class);
		html(">");
		html_txt(path);
		html("</span>");
	}
	html_txtf(" @ %.7s", rev);
	if (item && tail)
		path[len - 1] = tail;
}

struct date_mode cgit_date_mode(enum date_mode_type type)
{
	static struct date_mode mode;
	mode.type = type;
	mode.local = ctx.cfg.local_time;
	return mode;
}

void cgit_print_age(time_t t, int tz, time_t max_relative)
{
	time_t now, secs;

	if (!t)
		return;
	time(&now);
	secs = now - t;
	if (secs < 0)
		secs = 0;

	if (!ctx.cfg.enable_relative_dates ||
	    (secs > max_relative && max_relative >= 0)) {
		print_abs_date(t, tz);
		return;
	}

	if (secs < SECONDS_PER_HOUR * 2) {
		print_rel_date(t, tz, secs * 1.0 / SECONDS_PER_MINUTE,
			       "age-mins", "min.");
		return;
	}
	if (secs < SECONDS_PER_DAY * 2) {
		print_rel_date(t, tz, secs * 1.0 / SECONDS_PER_HOUR,
			       "age-hours", "hours");
		return;
	}
	if (secs < SECONDS_PER_WEEK * 2) {
		print_rel_date(t, tz, secs * 1.0 / SECONDS_PER_DAY,
			       "age-days", "days");
		return;
	}
	if (secs < SECONDS_PER_MONTH * 2) {
		print_rel_date(t, tz, secs * 1.0 / SECONDS_PER_WEEK,
			       "age-weeks", "weeks");
		return;
	}
	if (secs < SECONDS_PER_YEAR * 2) {
		print_rel_date(t, tz, secs * 1.0 / SECONDS_PER_MONTH,
			       "age-months", "months");
		return;
	}
	print_rel_date(t, tz, secs * 1.0 / SECONDS_PER_YEAR,
		       "age-years", "years");
}

void cgit_print_http_headers(void)
{
	if (ctx.env.no_http && !strcmp(ctx.env.no_http, "1"))
		return;

	if (ctx.page.status)
		htmlf("Status: %d %s\n", ctx.page.status, ctx.page.statusmsg);
	if (ctx.page.mimetype && ctx.page.charset)
		htmlf("Content-Type: %s; charset=%s\n", ctx.page.mimetype,
		      ctx.page.charset);
	else if (ctx.page.mimetype)
		htmlf("Content-Type: %s\n", ctx.page.mimetype);
	if (ctx.page.size)
		htmlf("Content-Length: %zd\n", ctx.page.size);
	if (ctx.page.filename) {
		html("Content-Disposition: inline; filename=\"");
		html_header_arg_in_quotes(ctx.page.filename);
		html("\"\n");
	}
	if (!ctx.env.authenticated)
		html("Cache-Control: no-cache, no-store\n");
	htmlf("Last-Modified: %s\n", http_date(ctx.page.modified));
	htmlf("Expires: %s\n", http_date(ctx.page.expires));
	if (ctx.page.etag)
		htmlf("ETag: \"%s\"\n", ctx.page.etag);
	html("\n");
	// Some pages follow the headers with output written by git itself, not
	// through html_raw, so the buffer is emptied to keep the headers first.
	html_flush();
	if (ctx.env.request_method && !strcmp(ctx.env.request_method, "HEAD"))
		exit(0);
}

void cgit_redirect(const char *url, bool permanent)
{
	htmlf("Status: %d %s\n", permanent ? 301 : 302, permanent ? "Moved" : "Found");
	html("Location: ");
	html_url_path(url);
	html("\n\n");
}

void cgit_print_docstart(void)
{
	char *host = cgit_hosturl();

	if (ctx.cfg.embedded) {
		if (ctx.cfg.header)
			html_include(ctx.cfg.header);
		return;
	}

	html("<!DOCTYPE html>\n");
	html("<html lang='en' class='cgit-standalone'>\n");
	html("<head>\n");
	html("<meta charset='utf-8'>\n");
	html("<meta name='viewport' content='width=device-width, initial-scale=1'>\n");
	html("<meta name='color-scheme' content='light dark'>\n");
	html("<meta name='theme-color' media='(prefers-color-scheme: light)' content='#ffffff'>\n");
	html("<meta name='theme-color' media='(prefers-color-scheme: dark)' content='#1b1b1b'>\n");
	html("<title>");
	// An error page reached before a title was chosen still has to name
	// itself, since an empty title element is not valid.
	html_txt(ctx.page.title ? ctx.page.title : ctx.cfg.root_title);
	html("</title>\n");
	htmlf("<meta name='generator' content='cgit %s'>\n", cgit_version);
	if (ctx.cfg.robots && *ctx.cfg.robots) {
		html("<meta name='robots' content='");
		html_attr(ctx.cfg.robots);
		html("'>\n");
	}

	if (ctx.cfg.css.items)
		for_each_string_list(&ctx.cfg.css, emit_css_link, NULL);
	else
		emit_css_link(NULL, "/cgit.css");

	if (ctx.cfg.js.items)
		for_each_string_list(&ctx.cfg.js, emit_js_link, NULL);
	else
		emit_js_link(NULL, "/cgit.js");

	if (ctx.cfg.favicon && *ctx.cfg.favicon) {
		html("<link rel='icon' href='");
		html_attr(ctx.cfg.favicon);
		html("'>\n");
	}
	if (host && ctx.repo && ctx.qry.head) {
		char *fileurl;
		struct strbuf sb = STRBUF_INIT;
		strbuf_addf(&sb, "h=%s", ctx.qry.head);

		html("<link rel='alternate' title='Atom feed' href='");
		html(cgit_httpscheme());
		html_attr(host);
		fileurl = cgit_fileurl(ctx.repo->url, "atom", ctx.qry.vpath,
				       sb.buf);
		html_attr(fileurl);
		html("' type='application/atom+xml'>\n");
		strbuf_release(&sb);
		free(fileurl);
	}
	if (ctx.repo)
		cgit_add_clone_urls(print_rel_vcs_link);
	if (ctx.cfg.head_include)
		html_include(ctx.cfg.head_include);
	if (ctx.repo && ctx.repo->extra_head_content)
		html(ctx.repo->extra_head_content);
	html("</head>\n");
	html("<body>\n");
	if (ctx.cfg.header)
		html_include(ctx.cfg.header);
	free(host);
}

void cgit_print_docend(void)
{
	html("</main>\n");
	if (ctx.cfg.embedded) {
		html("</div> <!-- id=cgit -->\n");
		if (ctx.cfg.footer)
			html_include(ctx.cfg.footer);
		return;
	}
	if (ctx.cfg.footer)
		html_include(ctx.cfg.footer);
	else {
		htmlf("<footer class='footer'>generated by <a href='https://github.com/brycekwon/cgit'>cgit %s</a> "
			"(<a href='https://git-scm.com/'>git %s</a>) at ", cgit_version, git_version_string);
		html_txt(show_date(time(NULL), 0, cgit_date_mode(DATE_ISO8601)));
		html("</footer>\n");
	}
	html("</div> <!-- id=cgit -->\n");
	html("</body>\n</html>\n");
}

void cgit_print_error_page(int code, const char *msg, const char *fmt, ...)
{
	va_list ap;
	va_start(ap, fmt);
	cgit_vprint_error_page(code, msg, fmt, ap);
	va_end(ap);
}

void cgit_vprint_error_page(int code, const char *msg, const char *fmt,
			    va_list ap)
{
	ctx.page.expires = ctx.cfg.cache_dynamic_ttl;
	ctx.page.status = code;
	ctx.page.statusmsg = msg;
	cgit_print_layout_start();
	vprint_error(fmt, ap);
	cgit_print_layout_end();
}

void cgit_print_layout_start(void)
{
	cgit_print_http_headers();
	cgit_print_docstart();
	cgit_print_pageheader();
}

void cgit_print_layout_end(void)
{
	cgit_print_docend();
}

void cgit_add_clone_urls(void (*fn)(const char *))
{
	if (ctx.repo->clone_url)
		add_clone_urls(fn, cgit_expand_macros(ctx.repo->clone_url), NULL);
	else if (ctx.cfg.clone_prefix)
		add_clone_urls(fn, ctx.cfg.clone_prefix, ctx.repo->url);
}

void cgit_add_hidden_formfields(int incl_head, int incl_search,
				const char *page)
{
	if (!ctx.cfg.virtual_root) {
		struct strbuf url = STRBUF_INIT;

		strbuf_addf(&url, "%s/%s", ctx.qry.repo, page);
		if (ctx.qry.vpath)
			strbuf_addf(&url, "/%s", ctx.qry.vpath);
		html_hidden("url", url.buf);
		strbuf_release(&url);
	}

	if (incl_head && ctx.qry.head && ctx.repo->defbranch &&
	    strcmp(ctx.qry.head, ctx.repo->defbranch))
		html_hidden("h", ctx.qry.head);

	if (ctx.qry.oid)
		html_hidden("id", ctx.qry.oid);
	if (ctx.qry.oid2)
		html_hidden("id2", ctx.qry.oid2);
	if (ctx.qry.showmsg)
		html_hidden("showmsg", "1");

	if (incl_search) {
		if (ctx.qry.grep)
			html_hidden("qt", ctx.qry.grep);
		if (ctx.qry.search)
			html_hidden("q", ctx.qry.search);
	}
}

void cgit_print_pageheader(void)
{
	html("<div id='cgit'>");
	if (!ctx.env.authenticated || !ctx.cfg.noheader)
		print_header();

	if (ctx.env.authenticated)
		html("<nav class='tabs'>\n");
	if (ctx.env.authenticated && ctx.repo && ctx.empty_repo) {
		// Every other tab needs a commit to render and the search form
		// has nothing to search, so an empty repo gets summary alone.
		html("<ul>\n<li>");
		cgit_summary_link("summary", "Repository summary",
				  tab_class("summary"), ctx.qry.head);
		html("</li>\n</ul>\n");
	} else if (ctx.env.authenticated && ctx.repo) {
		print_repo_tabs();
		print_repo_search();
	} else if (ctx.env.authenticated) {
		print_site_tabs();
		print_site_search();
	}
	if (ctx.env.authenticated)
		html("</nav>\n");
	if (ctx.env.authenticated && ctx.repo && ctx.qry.vpath) {
		html("<nav class='path' aria-label='breadcrumb'>");
		html("path: ");
		print_path_crumbs(ctx.qry.vpath);
		if (ctx.repo->enable_follow_links && !strcmp(ctx.qry.page, "log")) {
			html(" (");
			ctx.qry.follow = !ctx.qry.follow;
			self_link(ctx.qry.follow ? "follow" : "unfollow",
				  NULL, NULL);
			ctx.qry.follow = !ctx.qry.follow;
			html(")");
		}
		html("</nav>");
	}
	html("<main class='content'>\n");
}

void cgit_print_filemode(unsigned short mode)
{
	if (S_ISDIR(mode))
		html("d");
	else if (S_ISLNK(mode))
		html("l");
	else if (S_ISGITLINK(mode))
		html("m");
	else
		html("-");
	html_fileperm(mode >> 6);
	html_fileperm(mode >> 3);
	html_fileperm(mode);
}

static void compose_snapshot_prefix(struct strbuf *filename, const char *base,
				  const char *ref)
{
	struct object_id oid;

	// A tag named v1.2 or V1.2 gives its snapshot the prettier name 1.2,
	// but only where dropping the letter cannot land two different tags on
	// one name, so that a snapshot can still be traced back to the tag it
	// was made from.
	if (repo_get_oid(the_repository, cgit_fmt("refs/tags/%s", ref), &oid) == 0 &&
	    (ref[0] == 'v' || ref[0] == 'V') && isdigit((unsigned char)ref[1]) &&
	    ((repo_get_oid(the_repository, cgit_fmt("refs/tags/%s", ref + 1), &oid) == 0) +
	     (repo_get_oid(the_repository, cgit_fmt("refs/tags/v%s", ref + 1), &oid) == 0) +
	     (repo_get_oid(the_repository, cgit_fmt("refs/tags/V%s", ref + 1), &oid) == 0) == 1))
		ref++;

	strbuf_addf(filename, "%s-%s", base, ref);
}

void cgit_print_snapshot_links(const struct cgit_repo *repo, const char *ref,
			       const char *separator)
{
	const struct cgit_snapshot_format *f;
	struct strbuf filename = STRBUF_INIT;
	const char *basename;
	size_t prefixlen;

	basename = cgit_snapshot_prefix(repo);
	if (starts_with(ref, basename))
		strbuf_addstr(&filename, ref);
	else
		compose_snapshot_prefix(&filename, basename, ref);

	prefixlen = filename.len;
	for (f = cgit_snapshot_formats; f->suffix; f++) {
		if (!(repo->snapshots & cgit_snapshot_format_bit(f)))
			continue;
		strbuf_setlen(&filename, prefixlen);
		strbuf_addstr(&filename, f->suffix);
		snapshot_link(filename.buf, NULL, NULL, NULL, NULL,
				   filename.buf);
		if (cgit_snapshot_get_sig(ref, f)) {
			strbuf_addstr(&filename, ".asc");
			html(" (");
			snapshot_link("sig", NULL, NULL, NULL, NULL,
					   filename.buf);
			html(")");
		} else if (starts_with(f->suffix, ".tar") && cgit_snapshot_get_sig(ref, &cgit_snapshot_formats[0])) {
			// A compressed tarball offers the signature made for
			// the plain tar it expands to, which is the first
			// format in the table.
			strbuf_setlen(&filename,
				      filename.len - strlen(f->suffix));
			strbuf_addstr(&filename, ".tar.asc");
			html(" (");
			snapshot_link("sig", NULL, NULL, NULL, NULL,
					   filename.buf);
			html(")");
		}
		html(separator);
	}
	strbuf_release(&filename);
}

void cgit_set_title_from_path(const char *path)
{
	struct strbuf sb = STRBUF_INIT;
	const char *slash, *last_slash;

	if (!path)
		return;

	// The path is read from the end so that the title names the file first
	// and the directories it sits in after it. The separator between them
	// is a guillemet, spelled here as the UTF-8 bytes of one.
	last_slash = path + strlen(path);
	while ((slash = find_last_char(path, last_slash, '/')) != NULL) {
		strbuf_add(&sb, slash + 1, last_slash - slash - 1);
		strbuf_addstr(&sb, " \xc2\xab ");
		last_slash = slash;
	}
	strbuf_add(&sb, path, last_slash - path);
	strbuf_addf(&sb, " - %s", ctx.page.title);
	ctx.page.title = strbuf_detach(&sb, NULL);
}