ui-stats: replace 'enable-stats' setting with 'max-stats'

The new 'max-stats' and 'repo.max-stats' settings makes it possible to
define the maximum statistics period, both globally and per repo. Hence,
it is now feasible to allow statistics on repositories with a high commit
frequency, like linux-2.6, by setting repo.max-stats to e.g. 'month'.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

8 files changed, 104 insertions, 58 deletions

diff --git a/cgit.c b/cgit.c
index 22b6d7c..57e11cd 100644
--- a/cgit.c
+++ b/cgit.c
@@ -3,24 +3,25 @@
  * Copyright (C) 2006 Lars Hjemli
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
  */
 
 #include "cgit.h"
 #include "cache.h"
 #include "cmd.h"
 #include "configfile.h"
 #include "html.h"
 #include "ui-shared.h"
+#include "ui-stats.h"
 #include "scan-tree.h"
 
 const char *cgit_version = CGIT_VERSION;
 
 void config_cb(const char *name, const char *value)
 {
 	if (!strcmp(name, "root-title"))
 		ctx.cfg.root_title = xstrdup(value);
 	else if (!strcmp(name, "root-desc"))
 		ctx.cfg.root_desc = xstrdup(value);
 	else if (!strcmp(name, "root-readme"))
 		ctx.cfg.root_readme = xstrdup(value);
@@ -45,26 +46,26 @@ void config_cb(const char *name, const char *value)
 		if (!ctx.cfg.virtual_root && (!strcmp(value, "/")))
 			ctx.cfg.virtual_root = "";
 	} else if (!strcmp(name, "nocache"))
 		ctx.cfg.nocache = atoi(value);
 	else if (!strcmp(name, "snapshots"))
 		ctx.cfg.snapshots = cgit_parse_snapshots_mask(value);
 	else if (!strcmp(name, "enable-index-links"))
 		ctx.cfg.enable_index_links = atoi(value);
 	else if (!strcmp(name, "enable-log-filecount"))
 		ctx.cfg.enable_log_filecount = atoi(value);
 	else if (!strcmp(name, "enable-log-linecount"))
 		ctx.cfg.enable_log_linecount = atoi(value);
-	else if (!strcmp(name, "enable-stats"))
-		ctx.cfg.enable_stats = atoi(value);
+	else if (!strcmp(name, "max-stats"))
+		ctx.cfg.max_stats = cgit_find_stats_period(value, NULL);
 	else if (!strcmp(name, "cache-size"))
 		ctx.cfg.cache_size = atoi(value);
 	else if (!strcmp(name, "cache-root"))
 		ctx.cfg.cache_root = xstrdup(value);
 	else if (!strcmp(name, "cache-root-ttl"))
 		ctx.cfg.cache_root_ttl = atoi(value);
 	else if (!strcmp(name, "cache-repo-ttl"))
 		ctx.cfg.cache_repo_ttl = atoi(value);
 	else if (!strcmp(name, "cache-static-ttl"))
 		ctx.cfg.cache_static_ttl = atoi(value);
 	else if (!strcmp(name, "cache-dynamic-ttl"))
 		ctx.cfg.cache_dynamic_ttl = atoi(value);
@@ -105,26 +106,26 @@ void config_cb(const char *name, const char *value)
 	else if (ctx.repo && !strcmp(name, "repo.desc"))
 		ctx.repo->desc = xstrdup(value);
 	else if (ctx.repo && !strcmp(name, "repo.owner"))
 		ctx.repo->owner = xstrdup(value);
 	else if (ctx.repo && !strcmp(name, "repo.defbranch"))
 		ctx.repo->defbranch = xstrdup(value);
 	else if (ctx.repo && !strcmp(name, "repo.snapshots"))
 		ctx.repo->snapshots = ctx.cfg.snapshots & cgit_parse_snapshots_mask(value); /* XXX: &? */
 	else if (ctx.repo && !strcmp(name, "repo.enable-log-filecount"))
 		ctx.repo->enable_log_filecount = ctx.cfg.enable_log_filecount * atoi(value);
 	else if (ctx.repo && !strcmp(name, "repo.enable-log-linecount"))
 		ctx.repo->enable_log_linecount = ctx.cfg.enable_log_linecount * atoi(value);
-	else if (ctx.repo && !strcmp(name, "repo.enable-stats"))
-		ctx.repo->enable_stats = ctx.cfg.enable_stats && atoi(value);
+	else if (ctx.repo && !strcmp(name, "repo.max-stats"))
+		ctx.repo->max_stats = cgit_find_stats_period(value, NULL);
 	else if (ctx.repo && !strcmp(name, "repo.module-link"))
 		ctx.repo->module_link= xstrdup(value);
 	else if (ctx.repo && !strcmp(name, "repo.readme") && value != NULL) {
 		if (*value == '/')
 			ctx.repo->readme = xstrdup(value);
 		else
 			ctx.repo->readme = xstrdup(fmt("%s/%s", ctx.repo->path, value));
 	} else if (!strcmp(name, "include"))
 		parse_configfile(value, config_cb);
 }
 
 static void querystring_cb(const char *name, const char *value)
@@ -174,24 +175,25 @@ static void prepare_context(struct cgit_context *ctx)
 	ctx->cfg.cache_repo_ttl = 5;
 	ctx->cfg.cache_root = CGIT_CACHE_ROOT;
 	ctx->cfg.cache_root_ttl = 5;
 	ctx->cfg.cache_static_ttl = -1;
 	ctx->cfg.css = "/cgit.css";
 	ctx->cfg.logo = "/git-logo.png";
 	ctx->cfg.local_time = 0;
 	ctx->cfg.max_repo_count = 50;
 	ctx->cfg.max_commit_count = 50;
 	ctx->cfg.max_lock_attempts = 5;
 	ctx->cfg.max_msg_len = 80;
 	ctx->cfg.max_repodesc_len = 80;
+	ctx->cfg.max_stats = 0;
 	ctx->cfg.module_link = "./?repo=%s&page=commit&id=%s";
 	ctx->cfg.renamelimit = -1;
 	ctx->cfg.robots = "index, nofollow";
 	ctx->cfg.root_title = "Git repository browser";
 	ctx->cfg.root_desc = "a fast webinterface for the git dscm";
 	ctx->cfg.script_name = CGIT_SCRIPT_NAME;
 	ctx->cfg.summary_branches = 10;
 	ctx->cfg.summary_log = 10;
 	ctx->cfg.summary_tags = 10;
 	ctx->page.mimetype = "text/html";
 	ctx->page.charset = PAGE_ENCODING;
 	ctx->page.filename = NULL;
diff --git a/cgit.h b/cgit.h
index 85045c4..f2cb671 100644
--- a/cgit.h
+++ b/cgit.h
@@ -52,25 +52,25 @@ struct cgit_repo {
 	char *name;
 	char *path;
 	char *desc;
 	char *owner;
 	char *defbranch;
 	char *group;
 	char *module_link;
 	char *readme;
 	char *clone_url;
 	int snapshots;
 	int enable_log_filecount;
 	int enable_log_linecount;
-	int enable_stats;
+	int max_stats;
 };
 
 struct cgit_repolist {
 	int length;
 	int count;
 	struct cgit_repo *repos;
 };
 
 struct commitinfo {
 	struct commit *commit;
 	char *author;
 	char *author_email;
@@ -144,31 +144,31 @@ struct cgit_config {
 	char *root_readme;
 	char *script_name;
 	char *virtual_root;
 	int cache_size;
 	int cache_dynamic_ttl;
 	int cache_max_create_time;
 	int cache_repo_ttl;
 	int cache_root_ttl;
 	int cache_static_ttl;
 	int enable_index_links;
 	int enable_log_filecount;
 	int enable_log_linecount;
-	int enable_stats;
 	int local_time;
 	int max_repo_count;
 	int max_commit_count;
 	int max_lock_attempts;
 	int max_msg_len;
 	int max_repodesc_len;
+	int max_stats;
 	int nocache;
 	int renamelimit;
 	int snapshots;
 	int summary_branches;
 	int summary_log;
 	int summary_tags;
 };
 
 struct cgit_page {
 	time_t modified;
 	time_t expires;
 	size_t size;
diff --git a/cgitrc.5.txt b/cgitrc.5.txt
index 60d3ea4..0bbbea3 100644
--- a/cgitrc.5.txt
+++ b/cgitrc.5.txt
@@ -65,28 +65,24 @@ enable-index-links
 	"commit" and "tree" pages). Default value: "0".
 
 enable-log-filecount
 	Flag which, when set to "1", will make cgit print the number of
 	modified files for each commit on the repository log page. Default
 	value: "0".
 
 enable-log-linecount
 	Flag which, when set to "1", will make cgit print the number of added
 	and removed lines for each commit on the repository log page. Default
 	value: "0".
 
-enable-stats
-	Globally enable/disable statistics for each repository. Default
-	value: "0".
-
 favicon
 	Url used as link to a shortcut icon for cgit. If specified, it is
 	suggested to use the value "/favicon.ico" since certain browsers will
 	ignore other values. Default value: none.
 
 footer
 	The content of the file specified with this option will be included
 	verbatim at the bottom of all pages (i.e. it replaces the standard
 	"generated by..." message. Default value: none.
 
 include
 	Name of a configfile to include before the rest of the current config-
@@ -124,24 +120,29 @@ max-commit-count
 max-message-length
 	Specifies the maximum number of commit message characters to display in
 	"log" view. Default value: "80".
 
 max-repo-count
 	Specifies the number of entries to list per page on the	repository
 	index page. Default value: "50".
 
 max-repodesc-length
 	Specifies the maximum number of repo description characters to display
 	on the repository index page. Default value: "80".
 
+max-stats
+	Set the default maximum statistics period. Valid values are "week",
+	"month", "quarter" and "year". If unspecified, statistics are
+	disabled. Default value: none. See also: "repo.max-stats".
+
 module-link
 	Text which will be used as the formatstring for a hyperlink when a
 	submodule is printed in a directory listing. The arguments for the
 	formatstring are the path and SHA1 of the submodule commit. Default
 	value: "./?repo=%s&page=commit&id=%s"
 
 nocache
 	If set to the value "1" caching will be disabled. This settings is
 	deprecated, and will not be honored starting with cgit-1.0. Default
 	value: "0".
 
 renamelimit
@@ -213,27 +214,28 @@ repo.defbranch
 
 repo.desc
 	The value to show as repository description. Default value: none.
 
 repo.enable-log-filecount
 	A flag which can be used to disable the global setting
 	`enable-log-filecount'. Default value: none.
 
 repo.enable-log-linecount
 	A flag which can be used to disable the global setting
 	`enable-log-linecount'. Default value: none.
 
-repo.enable-stats
-	A flag which can be used to disable the global setting
-	`enable-stats'. Default value: none.
+repo.max-stats
+	Override the default maximum statistics period. Valid values are equal
+	to the values specified for the global "max-stats" setting. Default
+	value: none.
 
 repo.name
 	The value to show as repository name. Default value: <repo.url>.
 
 repo.owner
 	A value used to identify the owner of the repository. Default value:
 	none.
 
 repo.path
 	An absolute path to the repository directory. For non-bare repositories
 	this is the .git-directory. Default value: none.
 
@@ -275,24 +277,28 @@ enable-log-filecount=1
 # Show number of added/removed lines per commit on the log pages
 enable-log-linecount=1
 
 
 # Add a cgit favicon
 favicon=/favicon.ico
 
 
 # Use a custom logo
 logo=/img/mylogo.png
 
 
+# Enable statistics per week, month and quarter
+max-stats=quarter
+
+
 # Set the title and heading of the repository index page
 root-title=foobar.com git repositories
 
 
 # Set a subheading for the repository index page
 root-desc=tracking the foobar development
 
 
 # Include some more info about foobar.com on the index page
 root-readme=/var/www/htdocs/about.html
 
 
@@ -347,24 +353,27 @@ repo.desc=the dscm
 
 
 repo.url=linux
 repo.path=/pub/git/linux.git
 repo.desc=the kernel
 
 # Disable adhoc downloads of this repo
 repo.snapshots=0
 
 # Disable line-counts for this repo
 repo.enable-log-linecount=0
 
+# Restrict the max statistics period for this repo
+repo.max-stats=month
+
 
 BUGS
 ----
 Comments currently cannot appear on the same line as a setting; the comment
 will be included as part of the value. E.g. this line:
 
 	robots=index  # allow indexing
 
 will generate the following html element:
 
 	<meta name='robots' content='index  # allow indexing'/>
 
diff --git a/cmd.c b/cmd.c
index 744bf84..763a558 100644
--- a/cmd.c
+++ b/cmd.c
@@ -103,28 +103,25 @@ static void refs_fn(struct cgit_context *ctx)
 	cgit_print_refs();
 }
 
 static void snapshot_fn(struct cgit_context *ctx)
 {
 	cgit_print_snapshot(ctx->qry.head, ctx->qry.sha1,
 			    cgit_repobasename(ctx->repo->url), ctx->qry.path,
 			    ctx->repo->snapshots, ctx->qry.nohead);
 }
 
 static void stats_fn(struct cgit_context *ctx)
 {
-	if (ctx->repo->enable_stats)
-		cgit_show_stats(ctx);
-	else
-		cgit_print_error("Stats disabled for this repo");
+	cgit_show_stats(ctx);
 }
 
 static void summary_fn(struct cgit_context *ctx)
 {
 	cgit_print_summary();
 }
 
 static void tag_fn(struct cgit_context *ctx)
 {
 	cgit_print_tag(ctx->qry.sha1);
 }
 
diff --git a/shared.c b/shared.c
index 37333f0..7382609 100644
--- a/shared.c
+++ b/shared.c
@@ -49,25 +49,25 @@ struct cgit_repo *cgit_add_repo(const char *url)
 
 	ret = &cgit_repolist.repos[cgit_repolist.count-1];
 	ret->url = trim_end(url, '/');
 	ret->name = ret->url;
 	ret->path = NULL;
 	ret->desc = "[no description]";
 	ret->owner = NULL;
 	ret->group = ctx.cfg.repo_group;
 	ret->defbranch = "master";
 	ret->snapshots = ctx.cfg.snapshots;
 	ret->enable_log_filecount = ctx.cfg.enable_log_filecount;
 	ret->enable_log_linecount = ctx.cfg.enable_log_linecount;
-	ret->enable_stats = ctx.cfg.enable_stats;
+	ret->max_stats = ctx.cfg.max_stats;
 	ret->module_link = ctx.cfg.module_link;
 	ret->readme = NULL;
 	return ret;
 }
 
 struct cgit_repo *cgit_get_repoinfo(const char *url)
 {
 	int i;
 	struct cgit_repo *repo;
 
 	for (i=0; i<cgit_repolist.count; i++) {
 		repo = &cgit_repolist.repos[i];
diff --git a/ui-shared.c b/ui-shared.c
index 0e688a0..97b9d46 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -632,25 +632,25 @@ void cgit_print_pageheader(struct cgit_context *ctx)
 		cgit_summary_link("summary", NULL, hc(cmd, "summary"),
 				  ctx->qry.head);
 		cgit_refs_link("refs", NULL, hc(cmd, "refs"), ctx->qry.head,
 			       ctx->qry.sha1, NULL);
 		cgit_log_link("log", NULL, hc(cmd, "log"), ctx->qry.head,
 			      NULL, NULL, 0, NULL, NULL);
 		cgit_tree_link("tree", NULL, hc(cmd, "tree"), ctx->qry.head,
 			       ctx->qry.sha1, NULL);
 		cgit_commit_link("commit", NULL, hc(cmd, "commit"),
 				 ctx->qry.head, ctx->qry.sha1);
 		cgit_diff_link("diff", NULL, hc(cmd, "diff"), ctx->qry.head,
 			       ctx->qry.sha1, ctx->qry.sha2, NULL);
-		if (ctx->repo->enable_stats)
+		if (ctx->repo->max_stats)
 			reporevlink("stats", "stats", NULL, hc(cmd, "stats"),
 				    ctx->qry.head, NULL, NULL);
 		if (ctx->repo->readme)
 			reporevlink("about", "about", NULL,
 				    hc(cmd, "about"), ctx->qry.head, NULL,
 				    NULL);
 		html("</td><td class='form'>");
 		html("<form class='right' method='get' action='");
 		if (ctx->cfg.virtual_root)
 			html_url_path(cgit_fileurl(ctx->qry.repo, "log",
 						   ctx->qry.path, NULL));
 		html("'>\n");
diff --git a/ui-stats.c b/ui-stats.c
index 3cc8d70..1104485 100644
--- a/ui-stats.c
+++ b/ui-stats.c
@@ -1,35 +1,21 @@
+#include <string-list.h>
+
 #include "cgit.h"
 #include "html.h"
-#include <string-list.h>
+#include "ui-shared.h"
+#include "ui-stats.h"
 
 #define MONTHS 6
 
-struct Period {
-	const char code;
-	const char *name;
-	int max_periods;
-	int count;
-
-	/* Convert a tm value to the first day in the period */
-	void (*trunc)(struct tm *tm);
-
-	/* Update tm value to start of next/previous period */
-	void (*dec)(struct tm *tm);
-	void (*inc)(struct tm *tm);
-
-	/* Pretty-print a tm value */
-	char *(*pretty)(struct tm *tm);
-};
-
 struct authorstat {
 	long total;
 	struct string_list list;
 };
 
 #define DAY_SECS (60 * 60 * 24)
 #define WEEK_SECS (DAY_SECS * 7)
 
 static void trunc_week(struct tm *tm)
 {
 	time_t t = timegm(tm);
 	t -= ((tm->tm_wday + 6) % 7) * DAY_SECS;
@@ -128,33 +114,57 @@ static void dec_year(struct tm *tm)
 }
 
 static void inc_year(struct tm *tm)
 {
 	tm->tm_year++;
 }
 
 static char *pretty_year(struct tm *tm)
 {
 	return fmt("%d", tm->tm_year + 1900);
 }
 
-struct Period periods[] = {
+struct cgit_period periods[] = {
 	{'w', "week", 12, 4, trunc_week, dec_week, inc_week, pretty_week},
 	{'m', "month", 12, 4, trunc_month, dec_month, inc_month, pretty_month},
 	{'q', "quarter", 12, 4, trunc_quarter, dec_quarter, inc_quarter, pretty_quarter},
 	{'y', "year", 12, 4, trunc_year, dec_year, inc_year, pretty_year},
 };
 
+/* Given a period code or name, return a period index (1, 2, 3 or 4)
+ * and update the period pointer to the correcsponding struct.
+ * If no matching code is found, return 0.
+ */
+int cgit_find_stats_period(const char *expr, struct cgit_period **period)
+{
+	int i;
+	char code = '\0';
+
+	if (!expr)
+		return 0;
+
+	if (strlen(expr) == 1)
+		code = expr[0];
+
+	for (i = 0; i < sizeof(periods) / sizeof(periods[0]); i++)
+		if (periods[i].code == code || !strcmp(periods[i].name, expr)) {
+			if (period)
+				*period = &periods[i];
+			return i+1;
+		}
+	return 0;
+}
+
 static void add_commit(struct string_list *authors, struct commit *commit,
-	struct Period *period)
+	struct cgit_period *period)
 {
 	struct commitinfo *info;
 	struct string_list_item *author, *item;
 	struct authorstat *authorstat;
 	struct string_list *items;
 	char *tmp;
 	struct tm *date;
 	time_t t;
 
 	info = cgit_parse_commit(commit);
 	tmp = xstrdup(info->author);
 	author = string_list_insert(tmp, authors);
@@ -181,25 +191,25 @@ static int cmp_total_commits(const void *a1, const void *a2)
 	const struct string_list_item *i1 = a1;
 	const struct string_list_item *i2 = a2;
 	const struct authorstat *auth1 = i1->util;
 	const struct authorstat *auth2 = i2->util;
 
 	return auth2->total - auth1->total;
 }
 
 /* Walk the commit DAG and collect number of commits per author per
  * timeperiod into a nested string_list collection.
  */
 struct string_list collect_stats(struct cgit_context *ctx,
-	struct Period *period)
+	struct cgit_period *period)
 {
 	struct string_list authors;
 	struct rev_info rev;
 	struct commit *commit;
 	const char *argv[] = {NULL, ctx->qry.head, NULL, NULL, NULL, NULL};
 	int argc = 3;
 	time_t now;
 	long i;
 	struct tm *tm;
 	char tmp[11];
 
 	time(&now);
@@ -224,25 +234,25 @@ struct string_list collect_stats(struct cgit_context *ctx,
 	prepare_revision_walk(&rev);
 	memset(&authors, 0, sizeof(authors));
 	while ((commit = get_revision(&rev)) != NULL) {
 		add_commit(&authors, commit, period);
 		free(commit->buffer);
 		free_commit_list(commit->parents);
 	}
 	return authors;
 }
 
 void print_combined_authorrow(struct string_list *authors, int from, int to,
 	const char *name, const char *leftclass, const char *centerclass,
-	const char *rightclass, struct Period *period)
+	const char *rightclass, struct cgit_period *period)
 {
 	struct string_list_item *author;
 	struct authorstat *authorstat;
 	struct string_list *items;
 	struct string_list_item *date;
 	time_t now;
 	long i, j, total, subtotal;
 	struct tm *tm;
 	char *tmp;
 
 	time(&now);
 	tm = gmtime(&now);
@@ -262,25 +272,26 @@ void print_combined_authorrow(struct string_list *authors, int from, int to,
 			authorstat = author->util;
 			items = &authorstat->list;
 			date = string_list_lookup(tmp, items);
 			if (date)
 				subtotal += (size_t)date->util;
 		}
 		htmlf("<td class='%s'>%d</td>", centerclass, subtotal);
 		total += subtotal;
 	}
 	htmlf("<td class='%s'>%d</td></tr>", rightclass, total);
 }
 
-void print_authors(struct string_list *authors, int top, struct Period *period)
+void print_authors(struct string_list *authors, int top,
+		   struct cgit_period *period)
 {
 	struct string_list_item *author;
 	struct authorstat *authorstat;
 	struct string_list *items;
 	struct string_list_item *date;
 	time_t now;
 	long i, j, total;
 	struct tm *tm;
 	char *tmp;
 
 	time(&now);
 	tm = gmtime(&now);
@@ -330,61 +341,69 @@ void print_authors(struct string_list *authors, int top, struct Period *period)
 	print_combined_authorrow(authors, 0, authors->nr - 1, "Total",
 		"total", "sum", "sum", period);
 	html("</table>");
 }
 
 /* Create a sorted string_list with one entry per author. The util-field
  * for each author is another string_list which is used to calculate the
  * number of commits per time-interval.
  */
 void cgit_show_stats(struct cgit_context *ctx)
 {
 	struct string_list authors;
-	struct Period *period;
+	struct cgit_period *period;
 	int top, i;
+	const char *code = "w";
 
-	period = &periods[0];
-	if (ctx->qry.period) {
-		for (i = 0; i < sizeof(periods) / sizeof(periods[0]); i++)
-			if (periods[i].code == ctx->qry.period[0]) {
-				period = &periods[i];
-				break;
-			}
+	if (ctx->qry.period)
+		code = ctx->qry.period;
+
+	i = cgit_find_stats_period(code, &period);
+	if (!i) {
+		cgit_print_error(fmt("Unknown statistics type: %c", code));
+		return;
+	}
+	if (i > ctx->repo->max_stats) {
+		cgit_print_error(fmt("Statistics type disabled: %s",
+				     period->name));
+		return;
 	}
 	authors = collect_stats(ctx, period);
 	qsort(authors.items, authors.nr, sizeof(struct string_list_item),
 		cmp_total_commits);
 
 	top = ctx->qry.ofs;
 	if (!top)
 		top = 10;
 	htmlf("<h2>Commits per author per %s", period->name);
 	if (ctx->qry.path) {
 		html(" (path '");
 		html_txt(ctx->qry.path);
 		html("')");
 	}
 	html("</h2>");
 
 	html("<form method='get' action='.' style='float: right; text-align: right;'>");
 	if (strcmp(ctx->qry.head, ctx->repo->defbranch))
 		htmlf("<input type='hidden' name='h' value='%s'/>", ctx->qry.head);
-	html("Period: ");
-	html("<select name='period' onchange='this.form.submit();'>");
-	for (i = 0; i < sizeof(periods) / sizeof(periods[0]); i++)
-		htmlf("<option value='%c'%s>%s</option>",
-			periods[i].code,
-			period == &periods[i] ? " selected" : "",
-			periods[i].name);
-	html("</select><br/><br/>");
+	if (ctx->repo->max_stats > 1) {
+		html("Period: ");
+		html("<select name='period' onchange='this.form.submit();'>");
+		for (i = 0; i < ctx->repo->max_stats; i++)
+			htmlf("<option value='%c'%s>%s</option>",
+				periods[i].code,
+				period == &periods[i] ? " selected" : "",
+				periods[i].name);
+		html("</select><br/><br/>");
+	}
 	html("Authors: ");
 	html("");
 	html("<select name='ofs' onchange='this.form.submit();'>");
 	htmlf("<option value='10'%s>10</option>", top == 10 ? " selected" : "");
 	htmlf("<option value='25'%s>25</option>", top == 25 ? " selected" : "");
 	htmlf("<option value='50'%s>50</option>", top == 50 ? " selected" : "");
 	htmlf("<option value='100'%s>100</option>", top == 100 ? " selected" : "");
 	htmlf("<option value='-1'%s>All</option>", top == -1 ? " selected" : "");
 	html("</select>");
 	html("<noscript>&nbsp;&nbsp;<input type='submit' value='Reload'/></noscript>");
 	html("</form>");
 	print_authors(&authors, top, period);
diff --git a/ui-stats.h b/ui-stats.h
index f1d744c..4f13dba 100644
--- a/ui-stats.h
+++ b/ui-stats.h
@@ -1,8 +1,27 @@
 #ifndef UI_STATS_H
 #define UI_STATS_H
 
 #include "cgit.h"
 
+struct cgit_period {
+	const char code;
+	const char *name;
+	int max_periods;
+	int count;
+
+	/* Convert a tm value to the first day in the period */
+	void (*trunc)(struct tm *tm);
+
+	/* Update tm value to start of next/previous period */
+	void (*dec)(struct tm *tm);
+	void (*inc)(struct tm *tm);
+
+	/* Pretty-print a tm value */
+	char *(*pretty)(struct tm *tm);
+};
+
+extern int cgit_find_stats_period(const char *expr, struct cgit_period **period);
+
 extern void cgit_show_stats(struct cgit_context *ctx);
 
 #endif /* UI_STATS_H */