/*

 * Copyright (c) 2006-2009 Openismus GmbH

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

 * Boston, MA 02111-1307, USA.

 */

#include "gtkimcontextmultipress.h"

#include <string.h>

#include <gtk/gtk.h>

#include <gdk/gdkkeysyms.h>

#include <gtk/gtkimmodule.h>

#include <config.h>

#define AUTOMATIC_COMPOSE_TIMEOUT 1 /* seconds */

#define CONFIGURATION_FILENAME MULTIPRESS_CONFDIR G_DIR_SEPARATOR_S "im-multipress.conf"

/* This contains rows of characters that can be entered by pressing

 * a particular key repeatedly.  Each row has one key (such as GDK_a),

 * and an array of character strings, such as "a".

 */

typedef struct

{

  gchar **characters; /* array of strings */

  gsize n_characters; /* number of strings in the array */

}

KeySequence;

static GObjectClass *im_context_multipress_parent_class = NULL;

static GType         im_context_multipress_type = 0;

static void im_context_multipress_class_init (GtkImContextMultipressClass *klass);

static void im_context_multipress_init (GtkImContextMultipress *self);

static void im_context_multipress_finalize (GObject *obj);

static void load_config (GtkImContextMultipress *self);

static gboolean vfunc_filter_keypress (GtkIMContext *context,

                                       GdkEventKey  *event);

static void vfunc_reset (GtkIMContext *context);

static void vfunc_get_preedit_string (GtkIMContext   *context,

                                      gchar         **str,

                                      PangoAttrList **attrs,

                                      gint           *cursor_pos);

/* Notice that we have a *_register_type(GTypeModule*) function instead of a

 * *_get_type() function, because we must use g_type_module_register_type(),

 * providing the GTypeModule* that was provided to im_context_init(). That

 * is also why we are not using G_DEFINE_TYPE().

 */

void

gtk_im_context_multipress_register_type (GTypeModule* type_module)

{

  const GTypeInfo im_context_multipress_info =

    {

      sizeof (GtkImContextMultipressClass),

      (GBaseInitFunc) NULL,

      (GBaseFinalizeFunc) NULL,

      (GClassInitFunc) &im_context_multipress_class_init,

      NULL,

      NULL,

      sizeof (GtkImContextMultipress),

      0,

      (GInstanceInitFunc) &im_context_multipress_init,

      0,

    };

  im_context_multipress_type =

    g_type_module_register_type (type_module,

                                 GTK_TYPE_IM_CONTEXT,

                                 "GtkImContextMultipress",

                                 &im_context_multipress_info, 0);

}

GType

gtk_im_context_multipress_get_type (void)

{

  g_assert (im_context_multipress_type != 0);

  return im_context_multipress_type;

}

static void

key_sequence_free (gpointer value)

{

  KeySequence *seq = value;

  if (seq != NULL)

    {

      g_strfreev (seq->characters);

      g_slice_free (KeySequence, seq);

    }

}

static void

im_context_multipress_class_init (GtkImContextMultipressClass *klass)

{

  GtkIMContextClass *im_context_class;

  /* Set this so we can use it later: */

  im_context_multipress_parent_class = g_type_class_peek_parent (klass);

  /* Specify our vfunc implementations: */

  im_context_class = GTK_IM_CONTEXT_CLASS (klass);

  im_context_class->filter_keypress = &vfunc_filter_keypress;

  im_context_class->reset = &vfunc_reset;

  im_context_class->get_preedit_string = &vfunc_get_preedit_string;

  G_OBJECT_CLASS (klass)->finalize = &im_context_multipress_finalize;

}

static void

im_context_multipress_init (GtkImContextMultipress *self)

{

  self->key_sequences = g_hash_table_new_full (&g_direct_hash, &g_direct_equal,

                                               NULL, &key_sequence_free);

  load_config (self);

}

static void

im_context_multipress_finalize (GObject *obj)

{

  GtkImContextMultipress *self;

  self = GTK_IM_CONTEXT_MULTIPRESS (obj);

  /* Release the configuration data: */

  if (self->key_sequences != NULL)

    {

      g_hash_table_destroy (self->key_sequences);

      self->key_sequences = NULL;

    }

  (*im_context_multipress_parent_class->finalize) (obj);

}

GtkIMContext *

gtk_im_context_multipress_new (void)

{

  return (GtkIMContext *)g_object_new (GTK_TYPE_IM_CONTEXT_MULTIPRESS, NULL);

}

static void

cancel_automatic_timeout_commit (GtkImContextMultipress *multipress_context)

{

  if (multipress_context->timeout_id)

    g_source_remove (multipress_context->timeout_id);

  multipress_context->timeout_id = 0;

}

/* Clear the compose buffer, so we are ready to compose the next character.

 */

static void

clear_compose_buffer (GtkImContextMultipress *multipress_context)

{

  multipress_context->key_last_entered = 0;

  multipress_context->compose_count = 0;

  cancel_automatic_timeout_commit (multipress_context);

  if (multipress_context->tentative_match)

    {

      multipress_context->tentative_match = NULL;

      g_signal_emit_by_name (multipress_context, "preedit-changed");

      g_signal_emit_by_name (multipress_context, "preedit-end");

    }

}

/* Finish composing, provide the character, and clear our compose buffer.

 */

static void

accept_character (GtkImContextMultipress *multipress_context, const gchar *characters)

{

  /* Clear the compose buffer, so we are ready to compose the next character.

   * Note that if we emit "preedit-changed" after "commit", there's a segfault/

   * invalid-write with GtkTextView in gtk_text_layout_free_line_display(), when

   * destroying a PangoLayout (this can also be avoided by not using any Pango

   * attributes in get_preedit_string(). */

  clear_compose_buffer (multipress_context);

  /* Provide the character to GTK+ */

  g_signal_emit_by_name (multipress_context, "commit", characters);

}

static gboolean

on_timeout (gpointer data)

{

  GtkImContextMultipress *multipress_context;

  GDK_THREADS_ENTER ();

  multipress_context = GTK_IM_CONTEXT_MULTIPRESS (data);

  /* A certain amount of time has passed, so we will assume that the user

   * really wants the currently chosen character */

  accept_character (multipress_context, multipress_context->tentative_match);

  multipress_context->timeout_id = 0;

  GDK_THREADS_LEAVE ();

  return FALSE; /* don't call me again */

}

static gboolean

vfunc_filter_keypress (GtkIMContext *context, GdkEventKey *event)

{

  GtkIMContextClass      *parent;

  GtkImContextMultipress *multipress_context;

  multipress_context = GTK_IM_CONTEXT_MULTIPRESS (context);

  if (event->type == GDK_KEY_PRESS)

    {

      KeySequence *possible;

      /* Check whether the current key is the same as previously entered, because

       * if it is not then we should accept the previous one, and start a new

       * character. */

      if (multipress_context->compose_count > 0

          && multipress_context->key_last_entered != event->keyval

          && multipress_context->tentative_match != NULL)

        {

          /* Accept the previously chosen character.  This wipes

           * the compose_count and key_last_entered. */

          accept_character (multipress_context,

                            multipress_context->tentative_match);

        } 

      /* Decide what character this key press would choose: */

      possible = g_hash_table_lookup (multipress_context->key_sequences,

                                      GUINT_TO_POINTER (event->keyval));

      if (possible != NULL)

        {

          if (multipress_context->compose_count == 0)

            g_signal_emit_by_name (multipress_context, "preedit-start");

          /* Check whether we are at the end of a compose sequence, with no more

           * possible characters.  Cycle back to the start if necessary. */

          if (multipress_context->compose_count >= possible->n_characters)

            multipress_context->compose_count = 0;

          /* Store the last key pressed in the compose sequence. */

          multipress_context->key_last_entered = event->keyval; 

          /* Get the possible match for this number of presses of the key.

           * compose_count starts at 1, so that 0 can mean not composing. */ 

          multipress_context->tentative_match =

            possible->characters[multipress_context->compose_count++];

          /* Indicate the current possible character.  This will cause our

           * vfunc_get_preedit_string() vfunc to be called, which will provide

           * the current possible character for the user to see. */

          g_signal_emit_by_name (multipress_context, "preedit-changed");

          /* Cancel any outstanding timeout, so we can start the timer again: */

          cancel_automatic_timeout_commit (multipress_context);

          /* Create a timeout that will cause the currently chosen character to

           * be committed, if nothing happens for a certain amount of time: */

          multipress_context->timeout_id =

            g_timeout_add_seconds (AUTOMATIC_COMPOSE_TIMEOUT,

                                   &on_timeout, multipress_context);

          return TRUE; /* key handled */

        }

      else

        {

          guint32 keyval_uchar;

          /* Just accept all other keypresses directly, but commit the

           * current preedit content first. */

          if (multipress_context->compose_count > 0

              && multipress_context->tentative_match != NULL)

            {

              accept_character (multipress_context,

                                multipress_context->tentative_match);

            }

          keyval_uchar = gdk_keyval_to_unicode (event->keyval);

          /* Convert to a string for accept_character(). */

          if (keyval_uchar != 0)

            {

              /* max length of UTF-8 sequence = 6 + 1 for NUL termination */

              gchar keyval_utf8[7];

              gint  length;

              length = g_unichar_to_utf8 (keyval_uchar, keyval_utf8);

              keyval_utf8[length] = '\0';

              accept_character (multipress_context, keyval_utf8);

              return TRUE; /* key handled */

            }

        }

    }

  parent = (GtkIMContextClass *)im_context_multipress_parent_class;

  /* The default implementation just returns FALSE, but it is generally

   * a good idea to call the base class implementation: */

  if (parent->filter_keypress)

    return (*parent->filter_keypress) (context, event);

  return FALSE;

}

static void

vfunc_reset (GtkIMContext *context)

{

  clear_compose_buffer (GTK_IM_CONTEXT_MULTIPRESS (context));

}

static void

vfunc_get_preedit_string (GtkIMContext   *context,

                          gchar         **str,

                          PangoAttrList **attrs,

                          gint           *cursor_pos)

{

  gsize len_bytes = 0;

  gsize len_utf8_chars = 0;

  /* Show the user what character he will get if he accepts: */

  if (str != NULL)

    {

      const gchar *match;

      match = GTK_IM_CONTEXT_MULTIPRESS (context)->tentative_match;

      if (match == NULL)

        match = ""; /* *str must not be NUL */

      len_bytes = strlen (match); /* byte count */

      len_utf8_chars = g_utf8_strlen (match, len_bytes); /* character count */

      *str = g_strndup (match, len_bytes);

    }

  /* Underline it, to show the user that he is in compose mode: */

  if (attrs != NULL)

    {

      *attrs = pango_attr_list_new ();

      if (len_bytes > 0)

        {

          PangoAttribute *attr;

          attr = pango_attr_underline_new (PANGO_UNDERLINE_SINGLE);

          attr->start_index = 0;

          attr->end_index = len_bytes;

          pango_attr_list_insert (*attrs, attr);

        }

    }

  if (cursor_pos)

    *cursor_pos = len_utf8_chars;

}

/* Open the configuration file and fill in the key_sequences hash table

 * with key/character-list pairs taken from the [keys] group of the file.

 */

static void

load_config (GtkImContextMultipress *self)

{

  GKeyFile *key_file;

  GError   *error = NULL;

  gchar   **keys;

  gsize     n_keys = 0;

  gsize     i;

  key_file = g_key_file_new ();

  if (!g_key_file_load_from_file (key_file, CONFIGURATION_FILENAME,

                                  G_KEY_FILE_NONE, &error))

    {

      g_warning ("Error while trying to open the %s configuration file: %s",

                 CONFIGURATION_FILENAME, error->message);

      g_error_free (error);

      g_key_file_free (key_file);

      return;

    }

  keys = g_key_file_get_keys (key_file, "keys", &n_keys, &error);

  if (error != NULL)

    {

      g_warning ("Error while trying to read the %s configuration file: %s",

                 CONFIGURATION_FILENAME, error->message);

      g_error_free (error);

      g_key_file_free (key_file);

      return;

    }

  for (i = 0; i < n_keys; ++i)

    {

      KeySequence *seq;

      guint        keyval;

      keyval = gdk_keyval_from_name (keys[i]);

      if (keyval == GDK_VoidSymbol)

        {

          g_warning ("Error while trying to read the %s configuration file: "

                     "invalid key name \"%s\"",

                     CONFIGURATION_FILENAME, keys[i]);

          continue;

        }

      seq = g_slice_new (KeySequence);

      seq->characters = g_key_file_get_string_list (key_file, "keys", keys[i],

                                                    &seq->n_characters, &error);

      if (error != NULL)

        {

          g_warning ("Error while trying to read the %s configuration file: %s",

                     CONFIGURATION_FILENAME, error->message);

          g_error_free (error);

          error = NULL;

          g_slice_free (KeySequence, seq);

          continue;

        }

      /* Ownership of the KeySequence is taken over by the hash table */

      g_hash_table_insert (self->key_sequences, GUINT_TO_POINTER (keyval), seq);

    }

  g_strfreev (keys);

  g_key_file_free (key_file);

}