/*
 * icons.[ch] written by Paolo Bacchilega, who writes:
 * "There is no problem for me, you can license my code
 * under whatever licence you wish :)"
 *
 */

#include <glib.h>
#include <gtk/gtk.h>
#include <gio/gio.h>
#include "icons.h"

#define VOID_PIXBUF_KEY "void-pixbuf"

static char const* get_static_string(char const* s)
{
    static GStringChunk* static_strings = NULL;

    if (s == NULL)
    {
        return NULL;
    }

    if (static_strings == NULL)
    {
        static_strings = g_string_chunk_new(1024);
    }

    return g_string_chunk_insert_const(static_strings, s);
}

typedef struct
{
    GtkIconTheme* icon_theme;
    int icon_size;
    GHashTable* cache;
} IconCache;

static IconCache* icon_cache[7] = { NULL, NULL, NULL, NULL, NULL, NULL, NULL };

static GdkPixbuf* create_void_pixbuf(int width, int height)
{
    GdkPixbuf* p;

    p = gdk_pixbuf_new(GDK_COLORSPACE_RGB, TRUE, 8, width, height);
    gdk_pixbuf_fill(p, 0xFFFFFF00);

    return p;
}

static int get_size_in_pixels(GtkIconSize icon_size)
{
    int width = 0;
    int height = 0;
    gtk_icon_size_lookup(icon_size, &width, &height);
    return MAX(width, height);
}

static IconCache* icon_cache_new(GtkWidget* for_widget, int icon_size)
{
    g_return_val_if_fail(for_widget != NULL, NULL);

    IconCache* icons = g_new0(IconCache, 1);
    icons->icon_theme = gtk_icon_theme_get_for_screen(gtk_widget_get_screen(for_widget));
    icons->icon_size = get_size_in_pixels(icon_size);
    icons->cache = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, g_object_unref);

    g_hash_table_insert(icons->cache, (void*)VOID_PIXBUF_KEY, create_void_pixbuf(icons->icon_size, icons->icon_size));

    return icons;
}

static char const* _icon_cache_get_icon_key(GIcon* icon)
{
    char const* key = NULL;

    if (G_IS_THEMED_ICON(icon))
    {
        char** icon_names;
        char* name;

        g_object_get(icon, "names", &icon_names, NULL);
        name = g_strjoinv(",", icon_names);

        key = get_static_string(name);

        g_free(name);
        g_strfreev(icon_names);
    }
    else if (G_IS_FILE_ICON(icon))
    {
        GFile* file;
        char* filename;

        file = g_file_icon_get_file(G_FILE_ICON(icon));
        filename = g_file_get_path(file);

        key = get_static_string(filename);

        g_free(filename);
        g_object_unref(file);
    }

    return key;
}

static GdkPixbuf* get_themed_icon_pixbuf(GThemedIcon* icon, int size, GtkIconTheme* icon_theme)
{
    char** icon_names = NULL;
    GtkIconInfo* icon_info;
    GdkPixbuf* pixbuf;
    GError* error = NULL;

    g_object_get(icon, "names", &icon_names, NULL);

    icon_info = gtk_icon_theme_choose_icon(icon_theme, (char const**)icon_names, size, 0);

    if (icon_info == NULL)
    {
        icon_info = gtk_icon_theme_lookup_icon(icon_theme, "text-x-generic", size, GTK_ICON_LOOKUP_USE_BUILTIN);
    }

    pixbuf = gtk_icon_info_load_icon(icon_info, &error);

    if (pixbuf == NULL)
    {
        if (error != NULL && error->message != NULL)
        {
            g_warning("could not load icon pixbuf: %s\n", error->message);
        }

        g_clear_error(&error);
    }

#if GTK_CHECK_VERSION(3, 8, 0)
    g_object_unref(icon_info);
#else
    gtk_icon_info_free(icon_info);
#endif

    g_strfreev(icon_names);

    return pixbuf;
}

static GdkPixbuf* get_file_icon_pixbuf(GFileIcon* icon, int size)
{
    GFile* file;
    char* filename;
    GdkPixbuf* pixbuf;

    file = g_file_icon_get_file(icon);
    filename = g_file_get_path(file);
    pixbuf = gdk_pixbuf_new_from_file_at_size(filename, size, -1, NULL);
    g_free(filename);
    g_object_unref(file);

    return pixbuf;
}

static GdkPixbuf* _get_icon_pixbuf(GIcon* icon, int size, GtkIconTheme* theme)
{
    if (icon == NULL)
    {
        return NULL;
    }

    if (G_IS_THEMED_ICON(icon))
    {
        return get_themed_icon_pixbuf(G_THEMED_ICON(icon), size, theme);
    }

    if (G_IS_FILE_ICON(icon))
    {
        return get_file_icon_pixbuf(G_FILE_ICON(icon), size);
    }

    return NULL;
}

static GdkPixbuf* icon_cache_get_mime_type_icon(IconCache* icons, char const* mime_type)
{
    GIcon* icon = g_content_type_get_icon(mime_type);
    char const* key = _icon_cache_get_icon_key(icon);
    if (key == NULL)
    {
        key = VOID_PIXBUF_KEY;
    }

    g_return_val_if_fail(icons != NULL, NULL);
    GdkPixbuf* pixbuf = g_hash_table_lookup(icons->cache, key);
    if (pixbuf != NULL)
    {
        g_object_ref(pixbuf);
        g_object_unref(G_OBJECT(icon));
        return pixbuf;
    }

    pixbuf = _get_icon_pixbuf(icon, icons->icon_size, icons->icon_theme);

    if (pixbuf != NULL)
    {
        g_hash_table_insert(icons->cache, (gpointer)key, g_object_ref(pixbuf));
    }

    g_object_unref(G_OBJECT(icon));

    return pixbuf;
}

GdkPixbuf* gtr_get_mime_type_icon(char const* mime_type, GtkIconSize icon_size, GtkWidget* for_widget)
{
    int n;

    switch (icon_size)
    {
    case GTK_ICON_SIZE_MENU:
        n = 1;
        break;

    case GTK_ICON_SIZE_SMALL_TOOLBAR:
        n = 2;
        break;

    case GTK_ICON_SIZE_LARGE_TOOLBAR:
        n = 3;
        break;

    case GTK_ICON_SIZE_BUTTON:
        n = 4;
        break;

    case GTK_ICON_SIZE_DND:
        n = 5;
        break;

    case GTK_ICON_SIZE_DIALOG:
        n = 6;
        break;

    default: /*GTK_ICON_SIZE_INVALID*/
        n = 0;
        break;
    }

    if (icon_cache[n] == NULL)
    {
        icon_cache[n] = icon_cache_new(for_widget, icon_size);
    }

    return icon_cache_get_mime_type_icon(icon_cache[n], mime_type);
}

char const* gtr_get_mime_type_from_filename(char const* file)
{
    char* tmp = g_content_type_guess(file, NULL, 0, NULL);
    char const* ret = get_static_string(tmp);
    g_free(tmp);
    return ret;
}