/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"

interface nsIDOMWindow;
interface nsITextInputProcessorCallback;

/**
 * An nsITextInputProcessor instance is associated with a top level widget which
 * handles native IME.  It's associated by calling beginInputTransaction() or
 * beginInputTransactionForTests().  While an instance has composition, nobody
 * can steal the rights to make composition on the top level widget.  In other
 * words, if another instance is composing on a top level widget, either
 * beginInputTransaction() or beginInputTransactionForTests() returns false
 * (i.e., not throws an exception).
 *
 * NOTE: See nsITextInputProcessorCallback.idl for examples of |callback| in
 *       following examples,
 *
 * Example #1 JS-IME can start composition like this:
 *
 *   var TIP = Components.classes["@mozilla.org/text-input-processor;1"].
 *               createInstance(Components.interfaces.nsITextInputProcessor);
 *   if (!TIP.beginInputTransaction(window, callback)) {
 *     return; // You failed to get the rights to make composition
 *   }
 *   // Set new composition string first
 *   TIP.setPendingCompositionString("some-words-are-inputted");
 *   // Set clause information.
 *   TIP.appendClauseToPendingComposition(23, TIP.ATTR_RAW_CLAUSE);
 *   // Set caret position, this is optional.
 *   TIP.setCaretInPendingComposition(23);
 *   // Flush the pending composition
 *   if (!TIP.flushPendingComposition()) {
 *     // If it returns false, it fails to start composition.
 *     return;
 *   }
 *
 * Example #2 JS-IME can separate composition string to two or more clauses:
 *
 *   // First, set composition string again
 *   TIP.setPendingCompositionString("some-words-are-inputted");
 *   // Then, if "are" is selected to convert, there are 3 clauses:
 *   TIP.appendClauseToPendingComposition(11, TIP.ATTR_CONVERTED_CLAUSE);
 *   TIP.appendClauseToPendingComposition(3,  TIP.ATTR_SELECTED_CLAUSE);
 *   TIP.appendClauseToPendingComposition(9,  TIP.ATTR_CONVERTED_CLAUSE);
 *   // Show caret at the beginning of the selected clause
 *   TIP.setCaretInPendingComposition(11);
 *   // Flush the pending composition.  Note that if there is a composition,
 *   // flushPendingComposition() won't return false.
 *   TIP.flushPendingComposition();
 *
 * Example #3 JS-IME can commit composition with specific string with this:
 *
 *   // First, there is a composition.
 *   TIP.setPendingCompositionString("some-words-directly-inputted");
 *   TIP.appendClauseToPendingComposition(28, TIP.ATTR_RAW_CLAUSE);
 *   TIP.flushPendingComposition();
 *   // This is useful when user selects a commit string from candidate list UI
 *   // which is provided by JS-IME.
 *   TIP.commitComposition("selected-words-from-candidate-list");
 *
 * Example #4 JS-IME can commit composition with the last composition string
 *            without specifying commit string:
 *
 *   // First, there is a composition.
 *   TIP.setPendingCompositionString("some-words-will-be-commited");
 *   TIP.appendClauseToPendingComposition(27, TIP.ATTR_RAW_CLAUSE);
 *   TIP.flushPendingComposition();
 *   // This is useful when user just type Enter key.
 *   TIP.commitComposition();
 *
 * Example #5 JS-IME can cancel composition with this:
 *
 *   // First, there is a composition.
 *   TIP.setPendingCompositionString("some-words-will-be-canceled");
 *   TIP.appendClauseToPendingComposition(27, TIP.ATTR_RAW_CLAUSE);
 *   TIP.flushPendingComposition();
 *   // This is useful when user doesn't want to commit the composition.
 *   // FYI: This is same as TIP.commitComposition("") for now.
 *   TIP.cancelComposition();
 *
 * Example #6 JS-IME can insert text only with commitComposition():
 *
 *   if (!TIP.beginInputTransaction(window, callback)) {
 *     return; // You failed to get the rights to make composition
 *   }
 *   TIP.commitComposition("Some words");
 *
 * Example #7 JS-IME can start composition explicitly:
 *
 *   if (!TIP.beginInputTransaction(window, callback)) {
 *     return; // You failed to get the rights to make composition
 *   }
 *   // If JS-IME don't want to show composing string in the focused editor,
 *   // JS-IME can dispatch only compositionstart event with this.
 *   if (!TIP.startComposition()) {
 *     // Failed to start composition.
 *     return;
 *   }
 *   // And when user selects a result from UI of JS-IME, commit with it.
 *   TIP.commitComposition("selected-words");
 */

[scriptable, builtinclass, uuid(512f1efe-9e0f-48a4-b423-3936ef948f34)]
interface nsITextInputProcessor : nsISupports
{
  /**
   * When you create an instance, you must call beginInputTransaction() first
   * except when you created the instance for automated tests.
   *
   * @param aWindow         A DOM window.  The instance will look for a top
   *                        level widget from this.
   * @param aCallback       Callback interface which handles requests to
   *                        IME and notifications to IME.  This must not be
   *                        null.
   * @return                If somebody uses internal text input service for a
   *                        composition, this returns false.  Otherwise, returns
   *                        true.  I.e., only your TIP can create composition
   *                        when this returns true.  If this returns false,
   *                        your TIP should wait next chance.
   */
  boolean beginInputTransaction(in nsIDOMWindow aWindow,
                                in nsITextInputProcessorCallback aCallback);

  /**
   * When you create an instance for automated test, you must call
   * beginInputTransaction(), first.  See beginInputTransaction() for more
   * detail of this.
   * Note that aCallback can be null.  If it's null, nsITextInputProcessor
   * implementation will handle them automatically.
   */
  [optional_argc] boolean
    beginInputTransactionForTests(
      in nsIDOMWindow aWindow,
      [optional] in nsITextInputProcessorCallback aCallback);

  /**
   * startComposition() dispatches compositionstart event explicitly.
   * IME does NOT need to call this typically since compositionstart event
   * is automatically dispatched by sendPendingComposition() if
   * compositionstart event hasn't been dispatched yet.  If this is called
   * when compositionstart has already been dispatched, this throws an
   * exception.
   *
   * @return                Returns true if composition starts normally.
   *                        Otherwise, returns false because it might be
   *                        canceled by the web application.
   */
  boolean startComposition();

  /**
   * Set new composition string.  Pending composition will be flushed by
   * a call of flushPendingComposition().  However, if the new composition
   * string isn't empty, you need to call appendClauseToPendingComposition() to
   * fill all characters of aString with one or more clauses before flushing.
   * Note that if you need to commit or cancel composition, use
   * commitComposition() or cancelComposition().
   */
  void setPendingCompositionString(in DOMString aString);

  // ATTR_RAW_CLAUSE means that the clause hasn't been selected nor converted
  // yet.
  const unsigned long ATTR_RAW_CLAUSE           = 0x02;
  // ATTR_SELECTED_RAW_CLAUSE means that the clause hasn't been converted yet
  // but is selected for converting to the other string.
  const unsigned long ATTR_SELECTED_RAW_CLAUSE  = 0x03;
  // ATTR_CONVERTED_CLAUSE means that the clause has already been converted but
  // is not selected.  This does NOT mean that this clause isn't modifiable.
  const unsigned long ATTR_CONVERTED_CLAUSE     = 0x04;
  // ATTR_SELECTED_CLAUSE means that the clause has already been converted and
  // is selected.  In other words, the clause is being converted.
  const unsigned long ATTR_SELECTED_CLAUSE      = 0x05;

  /**
   * Append a clause to the pending composition.
   *
   * If you need to fill the pending composition string with a clause, you
   * should call this once.  For example:
   *   appendClauseToPendingComposition(compositionString.length,
   *                                    ATTR_RAW_CLAUSE);
   * is enough.  If you need to separate the pending composition string to
   * multiple clauses, you need to call this multiple times. For example,
   * if your pending composition string has three clauses and the second clause
   * is being converted:
   *  appendClauseToPendingComposition(firstClauseLength,
   *                                   ATTR_CONVERTED_CLAUSE);
   *  appendClauseToPendingComposition(secondClauseLength,
   *                                   ATTR_SELECTED_CLAUSE);
   *  appendClauseToPendingComposition(thirdClauseLength,
   *                                   ATTR_CONVERTED_CLAUSE);
   * Note that if sum of aLength mismatches length of the pending composition
   * string, flushPendingComposition() will throw an exception.  I.e.,
   * |firstClauseLength + secondClauseLength + thirdClauseLength| must be
   * same as the length of pending composition string.
   *
   * TODO: Should be able to specify custom clause style.
   *
   * @param aLength         Length of the clause.
   * @param aAttribute      One of ATTR_* constants.
   */
  void appendClauseToPendingComposition(in unsigned long aLength,
                                        in unsigned long aAttribute);

  /**
   * Set caret offset in the pending composition string.  If you don't need to
   * show a caret, you don't need to call this.
   *
   * @param aOffset         Caret offset in the pending composition string.
   *                        This must be between 0 and length of the pending
   *                        composition string.
   */
  void setCaretInPendingComposition(in unsigned long aOffset);

  /**
   * flushPendingComposition() must be called after
   * setPendingCompositionString() and appendClauseToPendingComposition()
   * (setCaretInPendingComposition() is optional) are called.
   *
   * Note that compositionstart will be automatically dispatched if this is
   * called when there is no composition.
   *
   * Note that if sum of lengths of appended clauses are not same as composition
   * string or caret offset is larger than the composition string length, this
   * throws an exception.
   *
   * @return                Returns true if there is a composition already or
   *                        starting composition automatically.
   *                        Otherwise, i.e., if it cannot start composition
   *                        automatically, e.g., canceled by web apps, returns
   *                        false.
   */
  boolean flushPendingComposition();

  /**
   * commitComposition() will commit composition.
   * If there is a composition which is started by the instance, this commits
   * the composition.  Otherwise, throws an exception.
   *
   * Note that if you tries to commit composition without specifying commit
   * string when there is no composition, this throws an exception.
   *
   * @param aCommitString   This is optional.  If this is not specified,
   *                        composition will be committed with the last
   *                        composing string.  Otherwise, committed with
   *                        the specified string.
   * @return                Returns true if there is a composition already or
   *                        starting composition automatically.
   *                        Otherwise, i.e., if it cannot start composition
   *                        automatically, e.g., canceled by web apps, returns
   *                        false.
   */
  [optional_argc]
    boolean commitComposition([optional] in DOMString aCommitString);

  /**
   * cancelComposition() will cancel composition.  This is for now the same as
   * calling commitComposition("").  However, in the future, this might work
   * better.  If your IME needs to cancel composition, use this instead of
   * commitComposition().
   *
   * Note that if you tries to cancel composition when there is no composition,
   * this throws an exception.
   */
  void cancelComposition();
};

%{C++
#define TEXT_INPUT_PROCESSOR_CID \
  { 0xcaaab47f, 0x1e31, 0x478e, \
    { 0x89, 0x19, 0x97, 0x09, 0x04, 0xe9, 0xcb, 0x72 } }
#define TEXT_INPUT_PROCESSOR_CONTRACTID \
  "@mozilla.org/text-input-processor;1"
%}
