import forEach from 'lodash.foreach';

const HIGH_PRIORITY = 10001;

function ReadOnly(
    eventBus,
    contextPad,
    dragging,
    directEditing,
    editorActions,
    modeling,
    palette,
    paletteProvider
) {
    this._readOnly = false;
    this._eventBus = eventBus;

    let self = this;
    eventBus.on('readOnly.changed', HIGH_PRIORITY, function(e) {
        self._readOnly = e.readOnly;

        if (e.readOnly) {
            directEditing.cancel();
            contextPad.close();
            dragging.cancel();
        }

        palette._update();
    });

    function intercept(obj, fnName, cb) {
        var fn = obj[fnName];
        obj[fnName] = function() {
            return cb.call(this, fn, arguments);
        };
    }

    function ignoreWhenReadOnly(obj, fnName) {
        intercept(obj, fnName, function(fn, args) {
            if (self._readOnly) {
                return;
            }

            return fn.apply(this, args);
        });
    }

    function throwIfReadOnly(obj, fnName) {
        intercept(obj, fnName, function(fn, args) {
            if (self._readOnly) {
                throw new Error('model is read-only');
            }

            return fn.apply(this, args);
        });
    }

    ignoreWhenReadOnly(contextPad, 'open');

    ignoreWhenReadOnly(dragging, 'init');

    ignoreWhenReadOnly(directEditing, 'activate');

    ignoreWhenReadOnly(editorActions._actions, 'undo');
    ignoreWhenReadOnly(editorActions._actions, 'redo');
    ignoreWhenReadOnly(editorActions._actions, 'copy');
    ignoreWhenReadOnly(editorActions._actions, 'paste');
    ignoreWhenReadOnly(editorActions._actions, 'removeSelection');
    // BpmnEditorActions
    ignoreWhenReadOnly(editorActions._actions, 'spaceTool');
    ignoreWhenReadOnly(editorActions._actions, 'lassoTool');
    ignoreWhenReadOnly(editorActions._actions, 'globalConnectTool');
    ignoreWhenReadOnly(editorActions._actions, 'distributeElements');
    ignoreWhenReadOnly(editorActions._actions, 'alignElements');
    ignoreWhenReadOnly(editorActions._actions, 'directEditing');

    throwIfReadOnly(modeling, 'moveShape');
    throwIfReadOnly(modeling, 'updateAttachment');
    throwIfReadOnly(modeling, 'moveElements');
    throwIfReadOnly(modeling, 'moveConnection');
    throwIfReadOnly(modeling, 'layoutConnection');
    throwIfReadOnly(modeling, 'createConnection');
    throwIfReadOnly(modeling, 'createShape');
    throwIfReadOnly(modeling, 'createLabel');
    throwIfReadOnly(modeling, 'appendShape');
    throwIfReadOnly(modeling, 'removeElements');
    throwIfReadOnly(modeling, 'distributeElements');
    throwIfReadOnly(modeling, 'removeShape');
    throwIfReadOnly(modeling, 'removeConnection');
    throwIfReadOnly(modeling, 'replaceShape');
    throwIfReadOnly(modeling, 'pasteElements');
    throwIfReadOnly(modeling, 'alignElements');
    throwIfReadOnly(modeling, 'resizeShape');
    throwIfReadOnly(modeling, 'createSpace');
    throwIfReadOnly(modeling, 'updateWaypoints');
    throwIfReadOnly(modeling, 'reconnectStart');
    throwIfReadOnly(modeling, 'reconnectEnd');

    intercept(paletteProvider, 'getPaletteEntries', function(fn, args) {
        var entries = fn.apply(this, args);
        if (self._readOnly) {
            forEach(entries, function(value, key) {
                delete entries[key];
            });
        }
        return entries;
    });
}

ReadOnly.$inject = [
    'eventBus',
    'contextPad',
    'dragging',
    'directEditing',
    'editorActions',
    'modeling',
    'palette',
    'paletteProvider'
];

module.exports = ReadOnly;

ReadOnly.prototype.readOnly = function(readOnly) {
    var newValue = !!readOnly,
        oldValue = !!this._readOnly;

    if (readOnly === undefined || newValue === oldValue) {
        return oldValue;
    }

    this._readOnly = newValue;
    this._eventBus.fire('readOnly.changed', { readOnly: newValue });
    return newValue;
};