/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Ajax.org Code Editor (ACE).
 *
 * The Initial Developer of the Original Code is
 * Ajax.org B.V.
 * Portions created by the Initial Developer are Copyright (C) 2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *      Fabian Jakobs <fabian AT ajax DOT org>
 *      Julian Viereck <julian.viereck@gmail.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

define(function(require, exports, module) {

var oop = require("pilot/oop");
var lang = require("pilot/lang");
var EventEmitter = require("pilot/event_emitter").EventEmitter;
var Range = require("ace/range").Range;

/**
 * Keeps cursor position and the text selection of an edit session.
 * 
 * The row/columns used in the selection are in document coordinates
 * representing ths coordinates as thez appear in the document
 * before applying soft wrap and folding.
 */ 
var Selection = function(session) {
    this.session = session;
    this.doc = session.getDocument();

    this.clearSelection();
    this.selectionLead = this.doc.createAnchor(0, 0);
    this.selectionAnchor = this.doc.createAnchor(0, 0);

    var _self = this;
    this.selectionLead.on("change", function(e) {
        _self._dispatchEvent("changeCursor");
        if (!_self.$isEmpty)
            _self._dispatchEvent("changeSelection");
        if (!_self.$preventUpdateDesiredColumnOnChange && e.old.column != e.value.column)
            _self.$updateDesiredColumn();
    });

    this.selectionAnchor.on("change", function() {
        if (!_self.$isEmpty)
            _self._dispatchEvent("changeSelection");
    });
};

(function() {

    oop.implement(this, EventEmitter);

    this.isEmpty = function() {
        return (this.$isEmpty || (
            this.selectionAnchor.row == this.selectionLead.row &&
            this.selectionAnchor.column == this.selectionLead.column
        ));
    };

    this.isMultiLine = function() {
        if (this.isEmpty()) {
            return false;
        }

        return this.getRange().isMultiLine();
    };

    this.getCursor = function() {
        return this.selectionLead.getPosition();
    };

    this.setSelectionAnchor = function(row, column) {
        this.selectionAnchor.setPosition(row, column);

        if (this.$isEmpty) {
            this.$isEmpty = false;
            this._dispatchEvent("changeSelection");
        }
    };

    this.getSelectionAnchor = function() {
        if (this.$isEmpty)
            return this.getSelectionLead()
        else
            return this.selectionAnchor.getPosition();
    };

    this.getSelectionLead = function() {
        return this.selectionLead.getPosition();
    };

    this.shiftSelection = function(columns) {
        if (this.$isEmpty) {
            this.moveCursorTo(this.selectionLead.row, this.selectionLead.column + columns);
            return;
        };

        var anchor = this.getSelectionAnchor();
        var lead = this.getSelectionLead();

        var isBackwards = this.isBackwards();

        if (!isBackwards || anchor.column !== 0)
            this.setSelectionAnchor(anchor.row, anchor.column + columns);

        if (isBackwards || lead.column !== 0) {
            this.$moveSelection(function() {
                this.moveCursorTo(lead.row, lead.column + columns);
            });
        }
    };

    this.isBackwards = function() {
        var anchor = this.selectionAnchor;
        var lead = this.selectionLead;
        return (anchor.row > lead.row || (anchor.row == lead.row && anchor.column > lead.column));
    };

    this.getRange = function() {
        var anchor = this.selectionAnchor;
        var lead = this.selectionLead;

        if (this.isEmpty())
            return Range.fromPoints(lead, lead);

        if (this.isBackwards()) {
            return Range.fromPoints(lead, anchor);
        }
        else {
            return Range.fromPoints(anchor, lead);
        }
    };

    this.clearSelection = function() {
        if (!this.$isEmpty) {
            this.$isEmpty = true;
            this._dispatchEvent("changeSelection");
        }
    };

    this.selectAll = function() {
        var lastRow = this.doc.getLength() - 1;
        this.setSelectionAnchor(lastRow, this.doc.getLine(lastRow).length);
        this.moveCursorTo(0, 0);
    };

    this.setSelectionRange = function(range, reverse) {
        if (reverse) {
            this.setSelectionAnchor(range.end.row, range.end.column);
            this.selectTo(range.start.row, range.start.column);
        } else {
            this.setSelectionAnchor(range.start.row, range.start.column);
            this.selectTo(range.end.row, range.end.column);
        }
        this.$updateDesiredColumn();
    };

    this.$updateDesiredColumn = function() {
        var cursor = this.getCursor();
        this.$desiredColumn = this.session.documentToScreenColumn(cursor.row, cursor.column);
    };

    this.$moveSelection = function(mover) {
        var lead = this.selectionLead;
        if (this.$isEmpty)
            this.setSelectionAnchor(lead.row, lead.column);

        mover.call(this);
    };

    this.selectTo = function(row, column) {
        this.$moveSelection(function() {
            this.moveCursorTo(row, column);
        });
    };

    this.selectToPosition = function(pos) {
        this.$moveSelection(function() {
            this.moveCursorToPosition(pos);
        });
    };

    this.selectUp = function() {
        this.$moveSelection(this.moveCursorUp);
    };

    this.selectDown = function() {
        this.$moveSelection(this.moveCursorDown);
    };

    this.selectRight = function() {
        this.$moveSelection(this.moveCursorRight);
    };

    this.selectLeft = function() {
        this.$moveSelection(this.moveCursorLeft);
    };

    this.selectLineStart = function() {
        this.$moveSelection(this.moveCursorLineStart);
    };

    this.selectLineEnd = function() {
        this.$moveSelection(this.moveCursorLineEnd);
    };

    this.selectFileEnd = function() {
        this.$moveSelection(this.moveCursorFileEnd);
    };

    this.selectFileStart = function() {
        this.$moveSelection(this.moveCursorFileStart);
    };

    this.selectWordRight = function() {
        this.$moveSelection(this.moveCursorWordRight);
    };

    this.selectWordLeft = function() {
        this.$moveSelection(this.moveCursorWordLeft);
    };

    this.selectWord = function() {
        var cursor = this.getCursor();
        var range  = this.session.getWordRange(cursor.row, cursor.column);
        this.setSelectionRange(range);
    };

    this.selectLine = function() {
        var rowStart = this.selectionLead.row;
        var rowEnd;

        var foldLine = this.session.getFoldLine(rowStart);
        if (foldLine) {
            rowStart = foldLine.start.row;
            rowEnd = foldLine.end.row;
        } else {
            rowEnd = rowStart;
        }
        this.setSelectionAnchor(rowStart, 0);
        this.$moveSelection(function() {
            this.moveCursorTo(rowEnd + 1, 0);
        });
    };

    this.moveCursorUp = function() {
        this.moveCursorBy(-1, 0);
    };

    this.moveCursorDown = function() {
        this.moveCursorBy(1, 0);
    };

    this.moveCursorLeft = function() {
        var cursor = this.selectionLead.getPosition(),
            fold;

        if (fold = this.session.getFoldAt(cursor.row, cursor.column, -1)) {
            this.moveCursorTo(fold.start.row, fold.start.column);
        } else if (cursor.column == 0) {
            // cursor is a line (start
            if (cursor.row > 0) {
                this.moveCursorTo(cursor.row - 1, this.doc.getLine(cursor.row - 1).length);
            }
        }
        else {
            var tabSize = this.session.getTabSize();
            if (this.session.isTabStop(cursor) && this.doc.getLine(cursor.row).slice(cursor.column-tabSize, cursor.column).split(" ").length-1 == tabSize)
                this.moveCursorBy(0, -tabSize);
            else
                this.moveCursorBy(0, -1);
        }
    };

    this.moveCursorRight = function() {
        var cursor = this.selectionLead.getPosition(),
            fold;
        if (fold = this.session.getFoldAt(cursor.row, cursor.column, 1)) {
            this.moveCursorTo(fold.end.row, fold.end.column);
        }
        else if (this.selectionLead.column == this.doc.getLine(this.selectionLead.row).length) {
            if (this.selectionLead.row < this.doc.getLength() - 1) {
                this.moveCursorTo(this.selectionLead.row + 1, 0);
            }
        }
        else {
            var tabSize = this.session.getTabSize();
            var cursor = this.selectionLead;
            if (this.session.isTabStop(cursor) && this.doc.getLine(cursor.row).slice(cursor.column, cursor.column+tabSize).split(" ").length-1 == tabSize)
                this.moveCursorBy(0, tabSize);
            else
                this.moveCursorBy(0, 1);
        }
    };

    this.moveCursorLineStart = function() {
        var row = this.selectionLead.row;
        var column = this.selectionLead.column;
        var screenRow = this.session.documentToScreenRow(row, column);

        // Determ the doc-position of the first character at the screen line.
        var firstColumnPosition = this.session.screenToDocumentPosition(screenRow, 0);

        // Determ the line
        var beforeCursor = this.session.getDisplayLine(
            row, null,
            firstColumnPosition.row, firstColumnPosition.column
        );

        var leadingSpace = beforeCursor.match(/^\s*/);
        if (leadingSpace[0].length == column) {
            this.moveCursorTo(
                firstColumnPosition.row, firstColumnPosition.column
            );
        }
        else {
            this.moveCursorTo(
                firstColumnPosition.row,
                firstColumnPosition.column + leadingSpace[0].length
            );
        }
    };

    this.moveCursorLineEnd = function() {
        var lead = this.selectionLead;
        var lastRowColumnPosition =
            this.session.getDocumentLastRowColumnPosition(lead.row, lead.column);
        this.moveCursorTo(
            lastRowColumnPosition.row,
            lastRowColumnPosition.column
        );
    };

    this.moveCursorFileEnd = function() {
        var row = this.doc.getLength() - 1;
        var column = this.doc.getLine(row).length;
        this.moveCursorTo(row, column);
    };

    this.moveCursorFileStart = function() {
        this.moveCursorTo(0, 0);
    };

    this.moveCursorWordRight = function() {
        var row = this.selectionLead.row;
        var column = this.selectionLead.column;
        var line = this.doc.getLine(row);
        var rightOfCursor = line.substring(column);

        var match;
        this.session.nonTokenRe.lastIndex = 0;
        this.session.tokenRe.lastIndex = 0;

        var fold;
        if (fold = this.session.getFoldAt(row, column, 1)) {
            this.moveCursorTo(fold.end.row, fold.end.column);
            return;
        } else if (column == line.length) {
            this.moveCursorRight();
            return;
        }
        else if (match = this.session.nonTokenRe.exec(rightOfCursor)) {
            column += this.session.nonTokenRe.lastIndex;
            this.session.nonTokenRe.lastIndex = 0;
        }
        else if (match = this.session.tokenRe.exec(rightOfCursor)) {
            column += this.session.tokenRe.lastIndex;
            this.session.tokenRe.lastIndex = 0;
        }

        this.moveCursorTo(row, column);
    };

    this.moveCursorWordLeft = function() {
        var row = this.selectionLead.row;
        var column = this.selectionLead.column;

        var fold;
        if (fold = this.session.getFoldAt(row, column, -1)) {
            this.moveCursorTo(fold.start.row, fold.start.column);
            return;
        }

        if (column == 0) {
            this.moveCursorLeft();
            return;
        }

        var str = this.session.getFoldStringAt(row, column, -1);
        if (str == null) {
            str = this.doc.getLine(row).substring(0, column)
        }
        var leftOfCursor = lang.stringReverse(str);

        var match;
        this.session.nonTokenRe.lastIndex = 0;
        this.session.tokenRe.lastIndex = 0;

        if (match = this.session.nonTokenRe.exec(leftOfCursor)) {
            column -= this.session.nonTokenRe.lastIndex;
            this.session.nonTokenRe.lastIndex = 0;
        }
        else if (match = this.session.tokenRe.exec(leftOfCursor)) {
            column -= this.session.tokenRe.lastIndex;
            this.session.tokenRe.lastIndex = 0;
        }

        this.moveCursorTo(row, column);
    };

    this.moveCursorBy = function(rows, chars) {
        var screenPos = this.session.documentToScreenPosition(
            this.selectionLead.row,
            this.selectionLead.column
        );
        var screenCol = (chars == 0 && this.$desiredColumn) || screenPos.column;
        var docPos = this.session.screenToDocumentPosition(screenPos.row + rows, screenCol);
        this.moveCursorTo(docPos.row, docPos.column + chars, chars == 0);
    };

    this.moveCursorToPosition = function(position) {
        this.moveCursorTo(position.row, position.column);
    };

    this.moveCursorTo = function(row, column, preventUpdateDesiredColumn) {
        // Ensure the row/column is not inside of a fold.
        var fold = this.session.getFoldAt(row, column, 1);
        if (fold) {
            row = fold.start.row;
            column = fold.start.column;
        }
        
        this.$preventUpdateDesiredColumnOnChange = true;
        this.selectionLead.setPosition(row, column);
        this.$preventUpdateDesiredColumnOnChange = false;
        
        if (!preventUpdateDesiredColumn)
            this.$updateDesiredColumn(this.selectionLead.column);
    };

    this.moveCursorToScreen = function(row, column, preventUpdateDesiredColumn) {
        var pos = this.session.screenToDocumentPosition(row, column);
        row = pos.row;
        column = pos.column;
        this.moveCursorTo(row, column, preventUpdateDesiredColumn);
    };

}).call(Selection.prototype);

exports.Selection = Selection;
});