Enable directory browsing

Extracting the appropriate globs from the MIME database.

3 files changed, 363 insertions, 32 deletions

diff --git a/README.adoc b/README.adoc
index 111380d..851df6d 100644
--- a/README.adoc
+++ b/README.adoc
@@ -46,7 +46,8 @@ a package with the latest development version from Archlinux's AUR.
 Building and Running
 --------------------
 Build dependencies: Meson, pkg-config +
-Runtime dependencies: gtk+-3.0, libturbojpeg, LibRaw (optional)
+Runtime dependencies: gtk+-3.0, libturbojpeg, LibRaw (optional),
+shared-mime-info
 
  $ git clone --recursive https://git.janouch.name/p/fastiv.git
  $ meson builddir
diff --git a/fastiv.c b/fastiv.c
index cc3e2ac..df02084 100644
--- a/fastiv.c
+++ b/fastiv.c
@@ -17,12 +17,15 @@
 
 #include <gtk/gtk.h>
 #include <glib.h>
+#include <glib/gstdio.h>
 
 #include <stdio.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <locale.h>
 
+#include <fnmatch.h>
+
 #include "config.h"
 #include "fastiv-view.h"
 
@@ -45,38 +48,313 @@ exit_fatal(const gchar *format, ...)
 	exit(EXIT_FAILURE);
 }
 
+/// Add `element` to the `output` set. `relation` is a map of sets of strings
+/// defining is-a relations, and is traversed recursively.
+static void
+add_applying_transitive_closure(const gchar *element, GHashTable *relation,
+	GHashTable *output)
+{
+	// Stop condition.
+	if (!g_hash_table_add(output, g_strdup(element)))
+		return;
+
+	// TODO(p): Iterate over all aliases of `element` in addition to
+	// any direct match (and rename this no-longer-generic function).
+	GHashTable *targets = g_hash_table_lookup(relation, element);
+	if (!targets)
+		return;
+
+	GHashTableIter iter;
+	g_hash_table_iter_init(&iter, targets);
+
+	gpointer key = NULL, value = NULL;
+	while (g_hash_table_iter_next(&iter, &key, &value))
+		add_applying_transitive_closure(key, relation, output);
+}
+
+// --- XDG ---------------------------------------------------------------------
+
+static gchar *
+get_xdg_home_dir(const char *var, const char *default_)
+{
+	const char *env = getenv(var);
+	if (env && *env == '/')
+		return g_strdup(env);
+
+	// The specification doesn't handle a missing HOME variable explicitly.
+	// Implicitly, assuming Bourne shell semantics, it simply resolves empty.
+	const char *home = getenv("HOME");
+	return g_build_filename(home ? home : "", default_, NULL);
+}
+
+static gchar **
+get_xdg_data_dirs(void)
+{
+	// GStrvBuilder is too new, it would help a little bit.
+	GPtrArray *output = g_ptr_array_new_with_free_func(g_free);
+	g_ptr_array_add(output, get_xdg_home_dir("XDG_DATA_HOME", ".local/share"));
+
+	const gchar *xdg_data_dirs;
+	if (!(xdg_data_dirs = getenv("XDG_DATA_DIRS")) || !*xdg_data_dirs)
+		xdg_data_dirs = "/usr/local/share/:/usr/share/";
+
+	gchar **candidates = g_strsplit(xdg_data_dirs, ":", 0);
+	for (gchar **p = candidates; *p; p++) {
+		if (**p == '/')
+			g_ptr_array_add(output, *p);
+		else
+			g_free(*p);
+	}
+	g_free(candidates);
+	g_ptr_array_add(output, NULL);
+	return (gchar **) g_ptr_array_free(output, FALSE);
+}
+
+// --- Filtering ---------------------------------------------------------------
+
+// Derived from shared-mime-info-spec 0.21.
+
+// TODO(p): Move to fastiv-io.c, expose the prototype in a header file
+// (perhaps finally start a new one for it).
+// A subset of shared-mime-info that produces an appropriate list of
+// file extensions. Chiefly motivated by the suckiness of RAW images:
+// someone else will maintain the list of file extensions for us.
+static const char *supported_media_types[] = {
+	"image/bmp",
+	"image/gif",
+	"image/png",
+	"image/jpeg",
+#ifdef HAVE_LIBRAW
+	"image/x-dcraw",
+#endif  // HAVE_LIBRAW
+};
+
+static void
+read_mime_subclasses(const gchar *path, GHashTable *subclass_sets)
+{
+	gchar *data = NULL;
+	if (!g_file_get_contents(path, &data, NULL /* length */, NULL /* error */))
+		return;
+
+	// The format of this file is unspecified,
+	// but in practice it's a list of space-separated media types.
+	gchar *datasave = NULL;
+	for (gchar *line = strtok_r(data, "\r\n", &datasave); line;
+			line = strtok_r(NULL, "\r\n", &datasave)) {
+		gchar *linesave = NULL,
+			*subclass = strtok_r(line, " ", &linesave),
+			*superclass = strtok_r(NULL, " ", &linesave);
+
+		// Nothing about comments is specified, we're being nice.
+		if (!subclass || *subclass == '#' || !superclass)
+			continue;
+
+		GHashTable *set = NULL;
+		if (!(set = g_hash_table_lookup(subclass_sets, superclass))) {
+			set = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
+			g_hash_table_insert(subclass_sets, g_strdup(superclass), set);
+		}
+		g_hash_table_add(set, g_strdup(subclass));
+	}
+	g_free(data);
+}
+
+static gboolean
+filter_mime_globs(const gchar *path, guint is_globs2, GHashTable *supported_set,
+	GHashTable *output_set)
+{
+	gchar *data = NULL;
+	if (!g_file_get_contents(path, &data, NULL /* length */, NULL /* error */))
+		return FALSE;
+
+	gchar *datasave = NULL;
+	for (const gchar *line = strtok_r(data, "\r\n", &datasave); line;
+			line = strtok_r(NULL, "\r\n", &datasave)) {
+		if (*line == '#')
+			continue;
+
+		// We do not support __NOGLOBS__, nor even parse out the "cs" flag.
+		// The weight is irrelevant.
+		gchar **f = g_strsplit(line, ":", 0);
+		if (g_strv_length(f) >= is_globs2 + 2) {
+			const gchar *type = f[is_globs2 + 0], *glob = f[is_globs2 + 1];
+			if (g_hash_table_contains(supported_set, type))
+				g_hash_table_add(output_set, g_utf8_strdown(glob, -1));
+		}
+		g_strfreev(f);
+	}
+	g_free(data);
+	return TRUE;
+}
+
+static gchar **
+get_supported_globs (void)
+{
+	gchar **data_dirs = get_xdg_data_dirs();
+
+	// The mime.cache format is inconvenient to parse,
+	// we'll do it from the text files manually, and once only.
+	GHashTable *subclass_sets = g_hash_table_new_full(g_str_hash, g_str_equal,
+		g_free, (GDestroyNotify) g_hash_table_destroy);
+	for (gsize i = 0; data_dirs[i]; i++) {
+		gchar *path =
+			g_build_filename(data_dirs[i], "mime", "subclasses", NULL);
+		read_mime_subclasses(path, subclass_sets);
+		g_free(path);
+	}
+
+	// A hash set of all supported media types, including subclasses,
+	// but not aliases.
+	GHashTable *supported =
+		g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
+	for (gsize i = 0; i < G_N_ELEMENTS(supported_media_types); i++) {
+		add_applying_transitive_closure(supported_media_types[i],
+			subclass_sets, supported);
+	}
+	g_hash_table_destroy(subclass_sets);
+
+	// We do not support the distinction of case-sensitive globs (:cs).
+	GHashTable *globs =
+		g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
+	for (gsize i = 0; data_dirs[i]; i++) {
+		gchar *path2 = g_build_filename(data_dirs[i], "mime", "globs2", NULL);
+		gchar *path1 = g_build_filename(data_dirs[i], "mime", "globs", NULL);
+		if (!filter_mime_globs(path2, TRUE, supported, globs))
+			filter_mime_globs(path1, FALSE, supported, globs);
+		g_free(path2);
+		g_free(path1);
+	}
+	g_strfreev(data_dirs);
+	g_hash_table_destroy(supported);
+
+	gchar **result = (gchar **) g_hash_table_get_keys_as_array(globs, NULL);
+	g_hash_table_steal_all(globs);
+	g_hash_table_destroy(globs);
+	return result;
+}
+
 // --- Main --------------------------------------------------------------------
 
 struct {
-	// TODO(p): Directory filenames, index within the list, ...
+	gchar **supported_globs;
+
+	gchar *directory;
+	GPtrArray *files;
+	gint files_index;
+
+	gchar *basename;
+
 	GtkWidget *window;
 	GtkWidget *view;
 } g;
 
+static gboolean
+is_supported(const gchar *filename)
+{
+	gchar *utf8 = g_filename_to_utf8(filename, -1, NULL, NULL, NULL);
+	if (!utf8)
+		return FALSE;
+
+	gchar *lowercased = g_utf8_strdown(utf8, -1);
+	g_free(utf8);
+
+	// XXX: fnmatch() uses the /locale/ encoding, but who cares nowadays.
+	for (gchar **p = g.supported_globs; *p; p++)
+		if (!fnmatch(*p, lowercased, 0)) {
+			g_free(lowercased);
+			return TRUE;
+		}
+
+	g_free(lowercased);
+	return FALSE;
+}
+
+static void
+show_error_dialog(GError *error)
+{
+	GtkWidget *dialog = gtk_message_dialog_new(GTK_WINDOW(g.window),
+		GTK_DIALOG_MODAL,
+		GTK_MESSAGE_ERROR, GTK_BUTTONS_CLOSE, "%s", error->message);
+	gtk_dialog_run(GTK_DIALOG(dialog));
+	gtk_widget_destroy(dialog);
+	g_error_free(error);
+}
+
+static void
+load_directory(const gchar *dirname)
+{
+	free(g.directory);
+	g.directory = g_strdup(dirname);
+	g_ptr_array_set_size(g.files, 0);
+	g.files_index = -1;
+
+	GError *error = NULL;
+	GDir *dir = g_dir_open(dirname, 0, &error);
+	if (dir) {
+		for (const gchar *name = NULL; (name = g_dir_read_name(dir)); ) {
+			if (!is_supported(name))
+				continue;
+
+			// XXX: We presume that this basename is from the same directory.
+			if (!g_strcmp0(g.basename, name))
+				g.files_index = g.files->len;
+
+			g_ptr_array_add(g.files, g_strdup(name));
+		}
+		g_dir_close(dir);
+	} else {
+		show_error_dialog(error);
+	}
+	g_ptr_array_add(g.files, NULL);
+
+	// XXX: When something outside the filtered entries is open, the index is
+	// kept at -1, and browsing doesn't work. How to behave here?
+	// Should we add it to the pointer array as an exception?
+}
+
 static void
 open(const gchar *path)
 {
+	g_return_if_fail(g_path_is_absolute(path));
+
 	GError *error = NULL;
 	if (!fastiv_view_open(FASTIV_VIEW(g.view), path, &error)) {
-		GtkWidget *dialog = gtk_message_dialog_new(GTK_WINDOW(g.window),
-			GTK_DIALOG_MODAL,
-			GTK_MESSAGE_ERROR, GTK_BUTTONS_CLOSE, "%s", error->message);
-		gtk_dialog_run(GTK_DIALOG(dialog));
-		gtk_widget_destroy(dialog);
+		show_error_dialog(error);
 		return;
 	}
 
 	gtk_window_set_title(GTK_WINDOW(g.window), path);
+
+	gchar *basename = g_path_get_basename(path);
+	g_free(g.basename);
+	g.basename = basename;
+
+	// So that load_directory() itself can be used for reloading.
+	gchar *dirname = g_path_get_dirname(path);
+	if (!g.directory || strcmp(dirname, g.directory)) {
+		load_directory(dirname);
+	} else {
+		g.files_index = -1;
+		for (guint i = 0; i + 1 < g.files->len; i++) {
+			if (!g_strcmp0(g.basename, g_ptr_array_index(g.files, i)))
+				g.files_index = i;
+		}
+	}
+	g_free(dirname);
+
 }
 
 static void
 on_open(void)
 {
+	// TODO(p): Populate and pass a GtkFileFilter.
+	// If we want to keep this functionality, that is.
 	GtkWidget *dialog = gtk_file_chooser_dialog_new("Open file",
 		GTK_WINDOW(g.window), GTK_FILE_CHOOSER_ACTION_OPEN,
 		"_Cancel", GTK_RESPONSE_CANCEL,
 		"_Open", GTK_RESPONSE_ACCEPT, NULL);
 
+	// The default is local-only, single item. Paths are returned absolute.
 	if (gtk_dialog_run(GTK_DIALOG(dialog)) == GTK_RESPONSE_ACCEPT) {
 		gchar *path = gtk_file_chooser_get_filename(GTK_FILE_CHOOSER(dialog));
 		open(path);
@@ -86,6 +364,33 @@ on_open(void)
 	gtk_widget_destroy(dialog);
 }
 
+static void
+on_previous(void)
+{
+	if (g.files_index >= 0) {
+		int previous =
+			(g.files->len - 1 + g.files_index - 1) % (g.files->len - 1);
+		char *absolute =
+			g_canonicalize_filename(g_ptr_array_index(g.files, previous),
+				g.directory);
+		open(absolute);
+		g_free(absolute);
+	}
+}
+
+static void
+on_next(void)
+{
+	if (g.files_index >= 0) {
+		int next = (g.files_index + 1) % (g.files->len - 1);
+		char *absolute =
+			g_canonicalize_filename(g_ptr_array_index(g.files, next),
+				g.directory);
+		open(absolute);
+		g_free(absolute);
+	}
+}
+
 int
 main(int argc, char *argv[])
 {
@@ -93,10 +398,10 @@ main(int argc, char *argv[])
 		exit_fatal("cannot set locale");
 
 	gboolean show_version = FALSE;
-	gchar **files = NULL;
+	gchar **path_args = NULL;
 	const GOptionEntry options[] = {
-		{G_OPTION_REMAINING, 0, 0, G_OPTION_ARG_FILENAME_ARRAY, &files,
-			NULL, "[FILE | DIRECTORY]..."},
+		{G_OPTION_REMAINING, 0, 0, G_OPTION_ARG_FILENAME_ARRAY, &path_args,
+			NULL, "[FILE | DIRECTORY]"},
 		{"version", 'V', G_OPTION_FLAG_IN_MAIN, G_OPTION_ARG_NONE,
 		 &show_version, "output version information and exit", NULL},
 		{},
@@ -111,6 +416,13 @@ main(int argc, char *argv[])
 		return 0;
 	}
 
+	// NOTE: Firefox and Eye of GNOME both interpret multiple arguments
+	// in a special way. This is problematic, because one-element lists
+	// are unrepresentable.
+	// TODO(p): Complain to the user if there's more than one argument.
+	// Best show the help message, if we can figure that out.
+	const gchar *path_arg = path_args ? path_args[0] : NULL;
+
 	gtk_window_set_default_icon_name(PROJECT_NAME);
 
 	g.view = g_object_new(FASTIV_TYPE_VIEW, NULL);
@@ -124,35 +436,53 @@ main(int argc, char *argv[])
 		g_cclosure_new(G_CALLBACK(gtk_main_quit), NULL, NULL));
 	gtk_accel_group_connect(accel_group, GDK_KEY_q, 0, 0,
 		g_cclosure_new(G_CALLBACK(gtk_main_quit), NULL, NULL));
+
 	gtk_accel_group_connect(accel_group, GDK_KEY_o, 0, 0,
 		g_cclosure_new(G_CALLBACK(on_open), NULL, NULL));
 	gtk_accel_group_connect(accel_group, GDK_KEY_o, GDK_CONTROL_MASK, 0,
 		g_cclosure_new(G_CALLBACK(on_open), NULL, NULL));
+
+	// FIXME: The left/right arrows do not work, for whatever reason.
+	gtk_accel_group_connect(accel_group, GDK_KEY_Left, 0, 0,
+		g_cclosure_new(G_CALLBACK(on_previous), NULL, NULL));
+	gtk_accel_group_connect(accel_group, GDK_KEY_Page_Up, 0, 0,
+		g_cclosure_new(G_CALLBACK(on_previous), NULL, NULL));
+	gtk_accel_group_connect(accel_group, GDK_KEY_Right, 0, 0,
+		g_cclosure_new(G_CALLBACK(on_next), NULL, NULL));
+	gtk_accel_group_connect(accel_group, GDK_KEY_Page_Down, 0, 0,
+		g_cclosure_new(G_CALLBACK(on_next), NULL, NULL));
+	gtk_accel_group_connect(accel_group, GDK_KEY_space, 0, 0,
+		g_cclosure_new(G_CALLBACK(on_next), NULL, NULL));
 	gtk_window_add_accel_group(GTK_WINDOW(g.window), accel_group);
 
-	// TODO(p): Load directory entries, store in `g`.
-	//  - Only when there's just one filename.
-	//     - stat() it if it's a dictionary or a filename;
-	//       can just blindly try to readdir(), followed by dirname and retry
-	//     - But how do we filter these? We don't want to have non-images
-	//       on the list.
-	//  - When there are multiple, just take them verbatim as a list.
-	//     - Not entirely sure about how much sense this makes,
-	//       we might want to rather open several windows, or simply fork,
-	//       or even disallow this completely.
-	gsize files_len = g_strv_length(files);
-	if (files_len) {
-		GDir *dir = NULL;
-		if ((dir = g_dir_open(files[0], 0, NULL))) {
-			const gchar *name = NULL;
-			while ((name = g_dir_read_name(dir)))
-				;
-			g_dir_close(dir);
-		}
+	g.supported_globs = get_supported_globs();
+	g.files = g_ptr_array_new_full(16, g_free);
+	gchar *cwd = g_get_current_dir();
 
-		open(files[0]);
+	// TODO(p): Desired behaviour:
+	//  - No arguments: show directory view of the current working directory.
+	//  - File argument: load its directory for browsing, open the file.
+	//  - Directory argument: load its directory for browsing, show the dir.
+	GStatBuf st;
+	if (!path_arg) {
+		load_directory(cwd);
+	} else if (g_stat(path_arg, &st)) {
+		show_error_dialog(g_error_new(G_FILE_ERROR,
+			g_file_error_from_errno(errno),
+			"%s: %s", path_arg, g_strerror(errno)));
+		load_directory(cwd);
+	} else {
+		gchar *path_arg_absolute = g_canonicalize_filename(path_arg, cwd);
+		if (S_ISDIR(st.st_mode))
+			load_directory(path_arg_absolute);
+		else
+			open(path_arg_absolute);
+		g_free(path_arg_absolute);
 	}
+	g_free(cwd);
 
+	// TODO(p): When no picture is loaded, show a view of this directory
+	// (we're missing a widget for that).
 	gtk_widget_show_all(g.window);
 	gtk_main();
 	return 0;
diff --git a/fastiv.desktop b/fastiv.desktop
index 38d747a..f048f98 100644
--- a/fastiv.desktop
+++ b/fastiv.desktop
@@ -7,5 +7,5 @@ Exec=fastiv %F
 Terminal=false
 StartupNotify=true
 Categories=Graphics;2DGraphics;Viewer;
-# TODO(p): Figure out how to include RAW MIME types, if appropriate.
-MimeType=image/png;image/bmp;image/x-bmp;image/x-MS-bmp;image/gif;image/jpeg;
+# TODO(p): Generate this list from source files.
+MimeType=image/png;image/bmp;image/gif;image/jpeg;image/x-dcraw;