/*
 * The Atom feed for a repository, which lists recent commits so a reader can
 * follow the project from a feed reader instead of the browsable pages. The
 * response is XML rather than a page, so this file writes its own HTTP headers
 * and never goes through the shared HTML layout.
 */

#define USE_THE_REPOSITORY_VARIABLE

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

/*
 * Atom timestamps have to be RFC 3339, so a feed ignores the date-format and
 * local-time settings the browsable pages honour. The zero is the timezone
 * offset, which pins every feed date to UTC.
 */
static const char *feed_date(timestamp_t when)
{
	return show_date(when, 0, date_mode_from_type(DATE_ISO8601_STRICT));
}

/*
 * cgit keeps an address with the angle brackets it was written with, while
 * Atom wants the bare address.
 */
static void print_email(const char *email)
{
	char *copy = xstrdup(email);
	char *start, *end;

	start = strchr(copy, '<');
	if (start)
		start++;
	else
		start = copy;
	end = strchr(start, '>');
	if (end)
		*end = '\0';

	html("<email>");
	html_txt(start);
	html("</email>\n");
	free(copy);
}

static void print_entry(struct commit *commit, const char *host)
{
	struct commitinfo *info;
	char *hex;

	info = cgit_parse_commit(commit);
	hex = oid_to_hex(&commit->object.oid);
	html("<entry>\n");
	html("<title>");
	html_txt(info->subject);
	html("</title>\n");
	html("<updated>");
	html_txt(feed_date(info->committer_date));
	html("</updated>\n");
	html("<author>\n");
	if (info->author) {
		html("<name>");
		html_txt(info->author);
		html("</name>\n");
	}
	if (info->author_email && !ctx.cfg.noplainemail)
		print_email(info->author_email);
	html("</author>\n");
	html("<published>");
	html_txt(feed_date(info->author_date));
	html("</published>\n");
	if (host) {
		char *pageurl;
		char delim = '&';

		html("<link rel='alternate' type='text/html' href='");
		html(cgit_httpscheme());
		html_attr(host);
		pageurl = cgit_pageurl(ctx.repo->url, "commit", NULL);
		html_attr(pageurl);
		// Without a virtual root the page url is already a query
		// string, so the commit id continues it instead of opening
		// one.
		if (ctx.cfg.virtual_root)
			delim = '?';
		html_attrf("%cid=%s", delim, hex);
		html("'/>\n");
		free(pageurl);
	}
	html("<id>");
	html_txtf("urn:%s:%s", the_hash_algo->name, hex);
	html("</id>\n");
	html("<content type='text'>\n");
	html_txt(info->msg);
	html("</content>\n");
	html("</entry>\n");
	cgit_free_commitinfo(info);
}

void cgit_print_atom(char *tip, const char *path, int max_count)
{
	char *host;
	// setup_revisions reads a command line, so the first slot is the
	// unused program name and parsing starts at the second.
	const char *argv[] = {NULL, tip, NULL, NULL, NULL};
	struct commit *commit;
	struct rev_info rev;
	int argc = 2;
	bool need_updated = true;

	if (ctx.qry.show_all)
		argv[1] = "--all";
	else if (!tip)
		argv[1] = ctx.qry.head;

	if (path) {
		argv[argc++] = "--";
		argv[argc++] = path;
	}

	repo_init_revisions(the_repository, &rev, NULL);
	rev.abbrev = DEFAULT_ABBREV;
	rev.commit_format = CMIT_FMT_DEFAULT;
	rev.verbose_header = 1;
	rev.show_root_diff = 0;
	rev.max_count = max_count;
	setup_revisions(argc, argv, &rev, NULL);
	prepare_revision_walk(&rev);

	host = cgit_hosturl();
	ctx.page.mimetype = "text/xml";
	ctx.page.charset = "utf-8";
	cgit_print_http_headers();
	html("<feed xmlns='http://www.w3.org/2005/Atom'>\n");
	html("<title>");
	html_txt(ctx.repo->name);
	if (path) {
		html("/");
		html_txt(path);
	}
	if (tip && !ctx.qry.show_all) {
		html(", branch ");
		html_txt(tip);
	}
	html("</title>\n");
	html("<subtitle>");
	html_txt(ctx.repo->desc);
	html("</subtitle>\n");
	if (host) {
		char *fullurl = cgit_currentfullurl();
		char *repourl = cgit_repourl(ctx.repo->url);
		html("<id>");
		html_txtf("%s%s%s", cgit_httpscheme(), host, fullurl);
		html("</id>\n");
		html("<link rel='self' href='");
		html_attrf("%s%s%s", cgit_httpscheme(), host, fullurl);
		html("'/>\n");
		html("<link rel='alternate' type='text/html' href='");
		html_attrf("%s%s%s", cgit_httpscheme(), host, repourl);
		html("'/>\n");
		free(fullurl);
		free(repourl);
	}
	while ((commit = get_revision(&rev)) != NULL) {
		if (need_updated) {
			html("<updated>");
			html_txt(feed_date(commit->date));
			html("</updated>\n");
			need_updated = false;
		}
		print_entry(commit, host);
		// release_commit_memory frees the parent list without clearing
		// the pointer to it, so drop the dangling reference here.
		release_commit_memory(the_repository->parsed_objects, commit);
		commit->parents = NULL;
	}
	if (need_updated) {
		// Atom makes a feed level updated mandatory, and an empty feed
		// has no commit to take one from.
		html("<updated>");
		html_txt(feed_date(time(NULL)));
		html("</updated>\n");
	}
	html("</feed>\n");
	free(host);
}