/*
 * MIT License
 *
 * Copyright (c) 2017 Serge Zaitsev
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#ifndef WEBVIEW_H
#define WEBVIEW_H

#ifdef __cplusplus
extern "C"
{
#endif

#ifdef WEBVIEW_STATIC
#define WEBVIEW_API static
#else
#define WEBVIEW_API extern
#endif

#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include <JavaScriptCore/JavaScript.h>
#include <gtk/gtk.h>
#include <webkit2/webkit2.h>

struct webview_priv
{
  GtkWidget *window;
  GtkWidget *scroller;
  GtkWidget *webview;
  GtkWidget *inspector_window;
  GAsyncQueue *queue;
  int ready;
  int js_busy;
  int should_exit;
};

struct webview;

typedef void (*webview_external_invoke_cb_t)(struct webview *w,
                                              const char *arg);

struct webview
{
  const char *url;
  const char *title;
  int width;
  int height;
  int resizable;
  int transparentTitlebar;
  int debug;
  webview_external_invoke_cb_t external_invoke_cb;
  struct webview_priv priv;
  void *userdata;
};

enum webview_dialog_type
{
  WEBVIEW_DIALOG_TYPE_OPEN = 0,
  WEBVIEW_DIALOG_TYPE_SAVE = 1,
  WEBVIEW_DIALOG_TYPE_ALERT = 2
};

#define WEBVIEW_DIALOG_FLAG_FILE (0 << 0)
#define WEBVIEW_DIALOG_FLAG_DIRECTORY (1 << 0)

#define WEBVIEW_DIALOG_FLAG_INFO (1 << 1)
#define WEBVIEW_DIALOG_FLAG_WARNING (2 << 1)
#define WEBVIEW_DIALOG_FLAG_ERROR (3 << 1)
#define WEBVIEW_DIALOG_FLAG_ALERT_MASK (3 << 1)

typedef void (*webview_dispatch_fn)(struct webview *w, void *arg);

struct webview_dispatch_arg
{
  webview_dispatch_fn fn;
  struct webview *w;
  void *arg;
};

#define DEFAULT_URL                                                            \
"data:text/"                                                                 \
"html,%3C%21DOCTYPE%20html%3E%0A%3Chtml%20lang=%22en%22%3E%0A%3Chead%3E%"    \
"3Cmeta%20charset=%22utf-8%22%3E%3Cmeta%20http-equiv=%22IE=edge%22%"         \
"20content=%22IE=edge%22%3E%3C%2Fhead%3E%0A%3Cbody%3E%3Cdiv%20id=%22app%22%" \
"3E%3C%2Fdiv%3E%3Cscript%20type=%22text%2Fjavascript%22%3E%3C%2Fscript%3E%"  \
"3C%2Fbody%3E%0A%3C%2Fhtml%3E"

#define CSS_INJECT_FUNCTION                                           \
"(function(e){var "                                                 \
"t=document.createElement('style'),d=document.head||document."      \
"getElementsByTagName('head')[0];t.setAttribute('type','text/"      \
"css'),t.styleSheet?t.styleSheet.cssText=e:t.appendChild(document." \
"createTextNode(e)),d.appendChild(t)})"

static const char *webview_check_url(const char *url)
{
  if (url == NULL || strlen(url) == 0)
  {
    return DEFAULT_URL;
  }
  return url;
}

WEBVIEW_API int webview(const char *title, const char *url, int width,
                        int height, int resizable);

WEBVIEW_API int webview_init(struct webview *w);
WEBVIEW_API int webview_loop(struct webview *w, int blocking);
WEBVIEW_API int webview_eval(struct webview *w, const char *js);
WEBVIEW_API int webview_inject_css(struct webview *w, const char *css);
WEBVIEW_API void webview_set_title(struct webview *w, const char *title);
WEBVIEW_API void webview_set_fullscreen(struct webview *w, int fullscreen);
WEBVIEW_API void webview_set_color(struct webview *w, uint8_t r, uint8_t g,
                                    uint8_t b, uint8_t a);
WEBVIEW_API void webview_dialog(struct webview *w,
                                enum webview_dialog_type dlgtype, int flags,
                                const char *title, const char *arg,
                                char *result, size_t resultsz, char *filter);
WEBVIEW_API void webview_dispatch(struct webview *w, webview_dispatch_fn fn,
                                  void *arg);
WEBVIEW_API void webview_terminate(struct webview *w);
WEBVIEW_API void webview_exit(struct webview *w);
WEBVIEW_API void webview_debug(const char *format, ...);
WEBVIEW_API void webview_print_log(const char *s);

WEBVIEW_API int webview(const char *title, const char *url, int width,
                        int height, int resizable)
{
  struct webview webview;
  memset(&webview, 0, sizeof(webview));
  webview.title = title;
  webview.url = url;
  webview.width = width;
  webview.height = height;
  webview.resizable = resizable;
  int r = webview_init(&webview);
  if (r != 0)
  {
    return r;
  }
  while (webview_loop(&webview, 1) == 0)
  {
  }
  webview_exit(&webview);
  return 0;
}

WEBVIEW_API void webview_debug(const char *format, ...)
{
  char buf[4096];
  va_list ap;
  va_start(ap, format);
  vsnprintf(buf, sizeof(buf), format, ap);
  webview_print_log(buf);
  va_end(ap);
}

static int webview_js_encode(const char *s, char *esc, size_t n)
{
  int r = 1; /* At least one byte for trailing zero */
  for (; *s; s++)
  {
    const unsigned char c = *s;
    if (c >= 0x20 && c < 0x80 && strchr("<>\\'\"", c) == NULL)
    {
      if (n > 0)
      {
        *esc++ = c;
        n--;
      }
      r++;
    }
    else
    {
      if (n > 0)
      {
        snprintf(esc, n, "\\x%02x", (int)c);
        esc += 4;
        n -= 4;
      }
      r += 4;
    }
  }
  return r;
}

WEBVIEW_API int webview_inject_css(struct webview *w, const char *css)
{
  int n = webview_js_encode(css, NULL, 0);
  char *esc = (char *)calloc(1, sizeof(CSS_INJECT_FUNCTION) + n + 4);
  if (esc == NULL)
  {
    return -1;
  }
  char *js = (char *)calloc(1, n);
  webview_js_encode(css, js, n);
  snprintf(esc, sizeof(CSS_INJECT_FUNCTION) + n + 4, "%s(\"%s\")",
            CSS_INJECT_FUNCTION, js);
  int r = webview_eval(w, esc);
  free(js);
  free(esc);
  return r;
}

static void external_message_received_cb(WebKitUserContentManager *m,
                                          WebKitJavascriptResult *r,
                                          gpointer arg)
{
  (void)m;
  struct webview *w = (struct webview *)arg;
  if (w->external_invoke_cb == NULL)
  {
    return;
  }
  JSGlobalContextRef context = webkit_javascript_result_get_global_context(r);
  JSValueRef value = webkit_javascript_result_get_value(r);
  JSStringRef js = JSValueToStringCopy(context, value, NULL);
  size_t n = JSStringGetMaximumUTF8CStringSize(js);
  char *s = g_new(char, n);
  JSStringGetUTF8CString(js, s, n);
  w->external_invoke_cb(w, s);
  JSStringRelease(js);
  g_free(s);
}

static void webview_load_changed_cb(WebKitWebView *webview,
                                    WebKitLoadEvent event, gpointer arg)
{
  (void)webview;
  struct webview *w = (struct webview *)arg;
  if (event == WEBKIT_LOAD_FINISHED)
  {
    w->priv.ready = 1;
  }
}

static void webview_destroy_cb(GtkWidget *widget, gpointer arg)
{
  (void)widget;
  struct webview *w = (struct webview *)arg;
  webview_terminate(w);
}

static gboolean webview_context_menu_cb(WebKitWebView *webview,
                                        GtkWidget *default_menu,
                                        WebKitHitTestResult *hit_test_result,
                                        gboolean triggered_with_keyboard,
                                        gpointer userdata)
{
  (void)webview;
  (void)default_menu;
  (void)hit_test_result;
  (void)triggered_with_keyboard;
  (void)userdata;
  return TRUE;
}

WEBVIEW_API int webview_init(struct webview *w)
{
  if (gtk_init_check(0, NULL) == FALSE)
  {
    return -1;
  }

  w->priv.ready = 0;
  w->priv.should_exit = 0;
  w->priv.queue = g_async_queue_new();
  w->priv.window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_title(GTK_WINDOW(w->priv.window), w->title);

  if (w->resizable)
  {
    gtk_window_set_default_size(GTK_WINDOW(w->priv.window), w->width,
                                w->height);
  }
  else
  {
    gtk_widget_set_size_request(w->priv.window, w->width, w->height);
  }
  gtk_window_set_resizable(GTK_WINDOW(w->priv.window), !!w->resizable);
  gtk_window_set_position(GTK_WINDOW(w->priv.window), GTK_WIN_POS_CENTER);

  w->priv.scroller = gtk_scrolled_window_new(NULL, NULL);
  gtk_container_add(GTK_CONTAINER(w->priv.window), w->priv.scroller);

  WebKitUserContentManager *m = webkit_user_content_manager_new();
  webkit_user_content_manager_register_script_message_handler(m, "external");
  g_signal_connect(m, "script-message-received::external",
                    G_CALLBACK(external_message_received_cb), w);

  w->priv.webview = webkit_web_view_new_with_user_content_manager(m);
  webkit_web_view_load_uri(WEBKIT_WEB_VIEW(w->priv.webview),
                            webview_check_url(w->url));
  g_signal_connect(G_OBJECT(w->priv.webview), "load-changed",
                    G_CALLBACK(webview_load_changed_cb), w);
  gtk_container_add(GTK_CONTAINER(w->priv.scroller), w->priv.webview);

  if (w->debug)
  {
    WebKitSettings *settings =
        webkit_web_view_get_settings(WEBKIT_WEB_VIEW(w->priv.webview));
    webkit_settings_set_enable_write_console_messages_to_stdout(settings, true);
    webkit_settings_set_enable_developer_extras(settings, true);
  }
  else
  {
    g_signal_connect(G_OBJECT(w->priv.webview), "context-menu",
                      G_CALLBACK(webview_context_menu_cb), w);
  }

  gtk_widget_show_all(w->priv.window);

  webkit_web_view_run_javascript(
      WEBKIT_WEB_VIEW(w->priv.webview),
      "window.external={invoke:function(x){"
      "window.webkit.messageHandlers.external.postMessage(x);}}",
      NULL, NULL, NULL);

  g_signal_connect(G_OBJECT(w->priv.window), "destroy",
                    G_CALLBACK(webview_destroy_cb), w);
  return 0;
}

WEBVIEW_API int webview_loop(struct webview *w, int blocking)
{
  gtk_main_iteration_do(blocking);
  return w->priv.should_exit;
}

WEBVIEW_API void webview_set_title(struct webview *w, const char *title)
{
  gtk_window_set_title(GTK_WINDOW(w->priv.window), title);
}

WEBVIEW_API void webview_set_fullscreen(struct webview *w, int fullscreen)
{
  if (fullscreen)
  {
    gtk_window_fullscreen(GTK_WINDOW(w->priv.window));
  }
  else
  {
    gtk_window_unfullscreen(GTK_WINDOW(w->priv.window));
  }
}

WEBVIEW_API void webview_set_color(struct webview *w, uint8_t r, uint8_t g,
                                    uint8_t b, uint8_t a)
{
  GdkRGBA color = {r / 255.0, g / 255.0, b / 255.0, a / 255.0};
  webkit_web_view_set_background_color(WEBKIT_WEB_VIEW(w->priv.webview),
                                        &color);
}

WEBVIEW_API void webview_dialog(struct webview *w,
                                enum webview_dialog_type dlgtype, int flags,
                                const char *title, const char *arg,
                                char *result, size_t resultsz, char *filter)
{
  GtkWidget *dlg;
  if (result != NULL)
  {
    result[0] = '\0';
  }
  if (dlgtype == WEBVIEW_DIALOG_TYPE_OPEN ||
      dlgtype == WEBVIEW_DIALOG_TYPE_SAVE)
  {
    dlg = gtk_file_chooser_dialog_new(
        title, GTK_WINDOW(w->priv.window),
        (dlgtype == WEBVIEW_DIALOG_TYPE_OPEN
              ? (flags & WEBVIEW_DIALOG_FLAG_DIRECTORY
                    ? GTK_FILE_CHOOSER_ACTION_SELECT_FOLDER
                    : GTK_FILE_CHOOSER_ACTION_OPEN)
              : GTK_FILE_CHOOSER_ACTION_SAVE),
        "_Cancel", GTK_RESPONSE_CANCEL,
        (dlgtype == WEBVIEW_DIALOG_TYPE_OPEN ? "_Open" : "_Save"),
        GTK_RESPONSE_ACCEPT, NULL);
    if (filter[0] != '\0') {
        GtkFileFilter *file_filter = gtk_file_filter_new();
        gchar **filters  = g_strsplit(filter, ",", -1);
        gint i;
        for(i = 0; filters && filters[i]; i++) {
            gtk_file_filter_add_pattern(file_filter, filters[i]);
        }
        gtk_file_filter_set_name(file_filter, filter);
        gtk_file_chooser_add_filter(GTK_FILE_CHOOSER(dlg), file_filter);
        g_strfreev(filters);
    }
    gtk_file_chooser_set_local_only(GTK_FILE_CHOOSER(dlg), FALSE);
    gtk_file_chooser_set_select_multiple(GTK_FILE_CHOOSER(dlg), FALSE);
    gtk_file_chooser_set_show_hidden(GTK_FILE_CHOOSER(dlg), TRUE);
    gtk_file_chooser_set_do_overwrite_confirmation(GTK_FILE_CHOOSER(dlg), TRUE);
    gtk_file_chooser_set_create_folders(GTK_FILE_CHOOSER(dlg), TRUE);
    gint response = gtk_dialog_run(GTK_DIALOG(dlg));
    if (response == GTK_RESPONSE_ACCEPT)
    {
      gchar *filename = gtk_file_chooser_get_filename(GTK_FILE_CHOOSER(dlg));
      g_strlcpy(result, filename, resultsz);
      g_free(filename);
    }
    gtk_widget_destroy(dlg);
  }
  else if (dlgtype == WEBVIEW_DIALOG_TYPE_ALERT)
  {
    GtkMessageType type = GTK_MESSAGE_OTHER;
    switch (flags & WEBVIEW_DIALOG_FLAG_ALERT_MASK)
    {
    case WEBVIEW_DIALOG_FLAG_INFO:
      type = GTK_MESSAGE_INFO;
      break;
    case WEBVIEW_DIALOG_FLAG_WARNING:
      type = GTK_MESSAGE_WARNING;
      break;
    case WEBVIEW_DIALOG_FLAG_ERROR:
      type = GTK_MESSAGE_ERROR;
      break;
    }
    dlg = gtk_message_dialog_new(GTK_WINDOW(w->priv.window), GTK_DIALOG_MODAL,
                                  type, GTK_BUTTONS_OK, "%s", title);
    gtk_message_dialog_format_secondary_text(GTK_MESSAGE_DIALOG(dlg), "%s",
                                              arg);
    gtk_dialog_run(GTK_DIALOG(dlg));
    gtk_widget_destroy(dlg);
  }
}

static void webview_eval_finished(GObject *object, GAsyncResult *result,
                                  gpointer userdata)
{
  (void)object;
  (void)result;
  struct webview *w = (struct webview *)userdata;
  w->priv.js_busy = 0;
}

WEBVIEW_API int webview_eval(struct webview *w, const char *js)
{
  while (w->priv.ready == 0)
  {
    g_main_context_iteration(NULL, TRUE);
  }
  w->priv.js_busy = 1;
  webkit_web_view_run_javascript(WEBKIT_WEB_VIEW(w->priv.webview), js, NULL,
                                  webview_eval_finished, w);
  while (w->priv.js_busy)
  {
    g_main_context_iteration(NULL, TRUE);
  }
  return 0;
}

static gboolean webview_dispatch_wrapper(gpointer userdata)
{
  struct webview *w = (struct webview *)userdata;
  for (;;)
  {
    struct webview_dispatch_arg *arg =
        (struct webview_dispatch_arg *)g_async_queue_try_pop(w->priv.queue);
    if (arg == NULL)
    {
      break;
    }
    (arg->fn)(w, arg->arg);
    g_free(arg);
  }
  return FALSE;
}

WEBVIEW_API void webview_dispatch(struct webview *w, webview_dispatch_fn fn,
                                  void *arg)
{
  struct webview_dispatch_arg *context =
      (struct webview_dispatch_arg *)g_new(struct webview_dispatch_arg *, 1);
  context->w = w;
  context->arg = arg;
  context->fn = fn;
  g_async_queue_lock(w->priv.queue);
  g_async_queue_push_unlocked(w->priv.queue, context);
  if (g_async_queue_length_unlocked(w->priv.queue) == 1)
  {
    gdk_threads_add_idle(webview_dispatch_wrapper, w);
  }
  g_async_queue_unlock(w->priv.queue);
}

WEBVIEW_API void webview_terminate(struct webview *w)
{
  w->priv.should_exit = 1;
}

WEBVIEW_API void webview_exit(struct webview *w) { (void)w; }
WEBVIEW_API void webview_print_log(const char *s)
{
  fprintf(stderr, "%s\n", s);
}

#ifdef __cplusplus
}
#endif

#endif /* WEBVIEW_H */