/*
 * The commit page, which shows one commit on its own and is where the log and
 * the ref listings link. It renders the idents, the object ids, the message,
 * the trailer table when the repository asks for one and any note, then hands
 * off to ui-diff.c for the diff against the first parent. Free text and
 * addresses are written through the repository's commit, trailer and email
 * filters, so a site can rewrite any of them on the way out.
 */

#define USE_THE_REPOSITORY_VARIABLE

#include "cgit.h"
#include "filter.h"
#include "html.h"
#include "parsing.h"
#include "shared.h"
#include "ui-commit.h"
#include "ui-diff.h"
#include "ui-log.h"
#include "ui-shared.h"

#include <list.h>
#include <mailmap.h>
#include <trailer.h>

// The diff below the message is always taken against the first parent alone,
// which says little about a merge of many branches, so a commit with this
// many parents or more is shown without a diff at all.
#define OCTOPUS_PARENTS 3

static void print_ident_row(const char *role, const char *name, const char *email,
	timestamp_t date, int tz)
{
	htmlf("<tr><th>%s</th><td>", role);
	cgit_open_filter(ctx.repo->email_filter, email ? email : "", "commit");
	html_txt(name);
	if (ctx.cfg.enable_plain_email) {
		html(" ");
		html_txt(email);
	}
	cgit_close_filter(ctx.repo->email_filter);
	html("</td><td class='right'><time datetime='");
	html_attr(show_date(date, tz, cgit_date_mode(DATE_ISO8601_STRICT)));
	html("'>");
	html_txt(show_date(date, tz, cgit_date_mode(DATE_ISO8601)));
	html("</time></td></tr>\n");
}

/*
 * Counts the parents that could be read and leaves the first of them in first,
 * which the diff below the message is taken against.
 */
static int print_parent_rows(struct commit *commit, const char *rev, const char *prefix,
	struct object_id *first)
{
	struct commit_list *p;
	struct commit *parent;
	struct commitinfo *info;
	const char *parent_hex, *label;
	int parents = 0;

	for (p = commit->parents; p; p = p->next) {
		parent = lookup_commit_reference(the_repository, &p->item->object.oid);
		if (!parent) {
			html("<tr><td colspan='3'>");
			cgit_print_error("Error reading parent commit");
			html("</td></tr>\n");
			continue;
		}
		if (!parents)
			oidcpy(first, &p->item->object.oid);
		html("<tr><th>parent</th><td colspan='2' class='oid'><div class='spanning'>");
		parent_hex = label = oid_to_hex(&p->item->object.oid);
		info = ctx.repo->enable_subject_links ? cgit_parse_commit(parent) : NULL;
		if (info)
			label = info->subject;
		cgit_commit_link(label, NULL, NULL, ctx.qry.head, parent_hex, prefix);
		if (info)
			cgit_free_commitinfo(info);
		html(" (");
		cgit_diff_link("diff", NULL, NULL, ctx.qry.head, rev, oid_to_hex(&p->item->object.oid),
			prefix);
		html(")</div></td></tr>\n");
		parents++;
	}
	return parents;
}

static void print_filtered_text(const char *text)
{
	cgit_open_filter(ctx.repo->commit_filter);
	html_txt(text);
	cgit_close_filter(ctx.repo->commit_filter);
}

/*
 * A value shaped like an ident is written the way the author row is, through
 * the mailmap and the email filter, and anything after the address, such as a
 * role in parentheses, follows as text. Anything else goes through the trailer
 * filter when one is set, and otherwise through the commit filter, so the
 * links a site already draws in message text keep appearing on trailer lines.
 */
static void print_trailer_value(const char *key, const char *value)
{
	struct ident_split ident;
	struct string_list *map;
	struct strbuf email = STRBUF_INIT;
	const char *name, *mail, *rest;
	size_t name_len, mail_len;

	if (!split_ident_line(&ident, value, strlen(value)) &&
		memchr(ident.mail_begin, '@', ident.mail_end - ident.mail_begin)) {
		name = ident.name_begin;
		name_len = ident.name_end - ident.name_begin;
		mail = ident.mail_begin;
		mail_len = ident.mail_end - ident.mail_begin;
		map = cgit_mailmap();
		if (map)
			map_user(map, &mail, &mail_len, &name, &name_len);
		strbuf_addch(&email, '<');
		strbuf_add(&email, mail, mail_len);
		strbuf_addch(&email, '>');
		cgit_open_filter(ctx.repo->email_filter, email.buf, "commit");
		html_ntxt(name, name_len);
		if (ctx.cfg.enable_plain_email) {
			html(" ");
			html_txt(email.buf);
		}
		cgit_close_filter(ctx.repo->email_filter);
		strbuf_release(&email);
		rest = ident.mail_end + 1;
		while (isspace((unsigned char)*rest))
			rest++;
		if (*rest) {
			html(" ");
			html_txt(rest);
		}
	} else if (ctx.repo->trailer_filter) {
		cgit_open_filter(ctx.repo->trailer_filter, key, "commit");
		html_txt(value);
		cgit_close_filter(ctx.repo->trailer_filter);
	} else {
		print_filtered_text(value);
	}
}

/*
 * One row per trailer, except that a run of trailers sharing a key, compared
 * without regard to case, becomes a single row listing every value. A line git
 * kept in the block without a value, such as a cherry-pick note or a key with
 * nothing after its colon, gets a row of its own as written.
 */
static void print_trailers(const char *msg)
{
	struct trailer_iterator iter;
	struct strbuf key = STRBUF_INIT, line = STRBUF_INIT;
	int open = 0;

	html("<table class='commit-trailers'>\n");
	trailer_iterator_init(&iter, msg);
	while (trailer_iterator_advance(&iter)) {
		if (!iter.val.len) {
			if (open)
				html("</td></tr>\n");
			open = 0;
			strbuf_reset(&line);
			strbuf_addstr(&line, iter.raw);
			strbuf_rtrim(&line);
			html("<tr><td colspan='2'>");
			print_filtered_text(line.buf);
			html("</td></tr>\n");
			continue;
		}
		if (open && !strcasecmp(key.buf, iter.key.buf))
			html("<br>");
		else {
			if (open)
				html("</td></tr>\n");
			strbuf_reset(&key);
			strbuf_addbuf(&key, &iter.key);
			html("<tr><th>");
			html_txt(key.buf);
			html("</th><td>");
			open = 1;
		}
		print_trailer_value(key.buf, iter.val.buf);
	}
	if (open)
		html("</td></tr>\n");
	html("</table>\n");
	trailer_iterator_release(&iter);
	strbuf_release(&key);
	strbuf_release(&line);
}

/*
 * Git finds the trailer block by looking at the whole message, title included,
 * so the subject goes back in front of the body before asking, and the offsets
 * that come back are shifted by that prefix. The blank line that separated the
 * body from its block is dropped along with the block.
 */
static void print_message(struct commitinfo *info)
{
	struct strbuf full = STRBUF_INIT;
	struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
	struct trailer_block *block;
	LIST_HEAD(items);
	size_t prefix, start, end;
	char *body = NULL;

	if (ctx.repo->enable_trailers) {
		strbuf_addf(&full, "%s\n\n%s", info->subject, info->msg);
		prefix = full.len - strlen(info->msg);
		opts.no_divider = 1;
		block = parse_trailers(&opts, full.buf, &items);
		start = trailer_block_start(block);
		end = trailer_block_end(block);
		free_trailers(&items);
		trailer_block_release(block);
		// git leaves trailing comment lines and an old style Conflicts
		// section after the block, which the split would lose, so such
		// a message is shown whole.
		if (start >= prefix && start < end && !full.buf[end + strspn(full.buf + end, "\n")]) {
			size_t len = start - prefix;

			while (len > 0 && info->msg[len - 1] == '\n')
				len--;
			body = xmemdupz(info->msg, len);
		}
	}

	html("<div class='commit-msg'>");
	print_filtered_text(body ? body : info->msg);
	html("</div>\n");
	if (body)
		print_trailers(full.buf);

	free(body);
	strbuf_release(&full);
}

void cgit_print_commit(char *hex, const char *prefix)
{
	struct commit *commit;
	struct commitinfo *info;
	struct strbuf notes = STRBUF_INIT;
	struct object_id oid, first_oid;
	const char *commit_hex;
	char *first_parent;
	char *tree_rev;
	int parents;

	if (!hex)
		hex = ctx.qry.head;

	if (repo_get_oid(the_repository, hex, &oid)) {
		cgit_print_error_page(404, "Not Found", "Bad object id: %s", hex);
		return;
	}
	commit = lookup_commit_reference(the_repository, &oid);
	if (!commit) {
		cgit_print_error_page(404, "Not Found", "Not a commit: %s", hex);
		return;
	}
	info = cgit_parse_commit(commit);

	format_display_notes(&commit->object.oid, &notes, PAGE_ENCODING, 1);

	load_ref_decorations(NULL, DECORATE_FULL_REFS);

	ctx.page.title = cgit_fmtalloc("%s - %s", info->subject, ctx.page.title);
	cgit_print_layout_start();
	cgit_print_diff_ctrls();

	html("<table class='commit-info'>\n");
	print_ident_row("author", info->author, info->author_email, info->author_date, info->author_tz);
	print_ident_row("committer", info->committer, info->committer_email,
		info->committer_date, info->committer_tz);

	// The spanning cells are kept out of the column widths, so a hash row
	// never pushes the dates away from the names above it.
	html("<tr><th>commit</th><td colspan='2' class='oid'><div class='spanning'>");
	commit_hex = oid_to_hex(&commit->object.oid);
	cgit_commit_link(commit_hex, NULL, NULL, ctx.qry.head, commit_hex, prefix);
	html(" (");
	cgit_patch_link("patch", NULL, NULL, NULL, commit_hex, prefix);
	html(")</div></td></tr>\n");

	// The parent rows follow the commit row so the commit hashes sit
	// together, leaving the tree beside the download links.
	parents = print_parent_rows(commit, hex, prefix, &first_oid);

	html("<tr><th>tree</th><td colspan='2' class='oid'><div class='spanning'>");
	tree_rev = xstrdup(hex);
	cgit_tree_link(oid_to_hex(get_commit_tree_oid(commit)), NULL, NULL, ctx.qry.head, tree_rev, NULL);
	if (prefix) {
		html(" /");
		cgit_tree_link(prefix, NULL, NULL, ctx.qry.head, tree_rev, prefix);
	}
	free(tree_rev);
	html("</div></td></tr>\n");

	if (ctx.repo->snapshots) {
		html("<tr><th>download</th><td colspan='2' class='oid'><div class='spanning'>");
		cgit_print_snapshot_links(ctx.repo, hex, "<br>");
		html("</div></td></tr>\n");
	}
	html("</table>\n");

	html("<div class='commit-subject'>");
	print_filtered_text(info->subject);
	cgit_print_commit_decorations(commit);
	html("</div>\n");
	print_message(info);
	if (notes.len != 0) {
		html("<div class='notes-header'>Notes</div>\n");
		html("<div class='notes'>");
		print_filtered_text(notes.buf);
		html("</div>\n");
		html("<div class='notes-footer'></div>\n");
	}

	if (parents < OCTOPUS_PARENTS) {
		first_parent = parents ? xstrdup(oid_to_hex(&first_oid)) : NULL;
		cgit_print_diff(ctx.qry.oid, first_parent, prefix, 0, 0);
		free(first_parent);
	}

	strbuf_release(&notes);
	cgit_free_commitinfo(info);
	cgit_print_layout_end();
}