class FSMDocument {

    constructor(name) {
        this.id = guid();
        this.name = name || null;
        this.createdAt = Date.now();
        this.lastModified = Date.now();
        this.element = null;
        this.unsaved = true;
        this.lastSavedHash = '';
        this.states = [];
        this.connections = [];
        this.changes = [];
        this.changesIndex = -1;
    }

    physicsTick() {
        this.states.forEach(stateA => {
            this.states.forEach(stateB => {
                if (stateA !== stateB && stateA.intersects(stateB)) {
                    const inter = stateA.intersection(stateB);
                    const angle1 = stateA.directionTo(stateB);
                    const angle2 = angle1 + Math.PI;

                    stateA.x += Math.cos(angle1) * inter;
                    stateA.y += Math.sin(angle1) * inter;
                    stateB.x += Math.cos(angle2) * inter;
                    stateB.y += Math.sin(angle2) * inter;
                }
            });
        });
    }

    tick() {
        this.states.forEach(state => {
            if (state.v) {
                state.moveToStep();
            }
        });

        if (!this.unsaved) {
            if (this.hashCode() !== this.lastSavedHash) {
                this.unsaved = true;
                this.element.classList.add('unsaved');
            }
        }
    }

    draw() {
        this.states.forEach(state => state.draw());
        this.connections.forEach(connection => connection.draw());
    }

    onDblClick(x, y) {
        if (!selectedObject) {
            selectedObject = new State(x, y);
            this.states.push(selectedObject);
            this.addChange('state', selectedObject.id, 'add', Object.keys(selectedObject), Object.values(selectedObject));
            resetCaret();
        } else if (selectedObject instanceof State) {
            selectedObject.isAcceptState = !selectedObject.isAcceptState;
            this.addChange('state', selectedObject.id, 'edit', ['isAcceptState'], [!selectedObject.isAcceptState]);
        }
    }

    onRightClick(x, y) {
        if (!selectedObject) {

        }
    }

    deleteCurrentObject() {
        if (!!selectedObject) {
            if (selectedObject instanceof State) {
                this.states.splice(this.states.findIndex(state => state === selectedObject), 1);
            }

            for (let i = 0; i < this.connections.length; i++) {
                const con = this.connections[i];
                if (con === selectedObject || con.state === selectedObject || con.stateA === selectedObject || con.stateB === selectedObject) {
                    this.connections.splice(i--, 1);
                }
            }

            selectedObject = null;
        }
    }

    getConnectionsOfState(state) {
        return this.connections.filter(connection => connection instanceof Connection && (connection.stateA === state || connection.stateB === state));
    }

    getConnectionsBetweenStates(stateA,stateB) {
        return this.getConnectionsOfState(stateA).filter(connection => connection.stateA === stateB || connection.stateB === stateB);
    }

    addChange(objectType, id, action, fields, oldValues, tryCombiningChanges) {
        if (this.changesIndex < this.changes.length - 1) {
            this.changes.splice(this.changesIndex + 1, this.changes.length - this.changesIndex - 1);
        }

        if (tryCombiningChanges) {
            let prevChange = this.changes[this.changesIndex];

            while (!!prevChange && prevChange.type === objectType && prevChange.id === id && prevChange.action === action && prevChange.fields.length === fields.length) {
                oldValues = prevChange.prevValues;
                this.changes.splice(this.changesIndex, 1);
                this.changesIndex--;
                prevChange = this.changes[this.changesIndex];
            }
        }

        this.changes.push({
            type: objectType,
            id,
            action,
            fields,
            prevValues: oldValues,
            date: Date.now()
        });
        this.changesIndex++;
    }

    undo(stepAmount) {
        if (stepAmount === 0)
            return;

        const loopAmount = Math.abs(stepAmount);
        const isRedo = stepAmount < 0;

        for (let i = 0; i < loopAmount; i++) {
            if (this.changes.length === 0 || (!isRedo && this.changesIndex < 0) || (isRedo && this.changesIndex >= this.changes.length - 1)) {
                return;
            }

            let change;
            if (isRedo) {
                this.changesIndex++;
                change = this.changes[this.changesIndex];
            } else {
                change = Object.assign({}, this.changes[this.changesIndex]);
                this.changesIndex--;

                change.action = change.action === 'add' ? 'remove' : change.action === 'remove' ? 'add' : 'edit';
            }

            if (change.type === 'state') {
                if (change.action === 'remove') {
                    this.states.splice(this.states.findIndex(item => item.id === change.id), 1);
                    return;
                }

                let state;
                if (change.action === 'add')
                    state = new State();
                else if (change.action === 'edit')
                    state = this.states.find(item => item.id === change.id);

                change.fields.forEach((field, index) => {
                    state[field] = change.prevValues[index];
                });

                if (change.action === 'add')
                    this.states.push(state);
            }

            if (change.type.indexOf('connection') !== -1) {
                if (change.action === 'remove') {
                    this.connections.splice(this.connections.findIndex(item => item.id === change.id), 1);
                    return;
                }

                let connection;
                if (change.action === 'add') {
                    if(change.type === 'startconnection')
                        connection = new StartConnection();
                    else if(change.type === 'selfconnection')
                        connection = new SelfConnection();
                    else
                        connection = new Connection();
                } else if (change.action === 'edit') {
                    connection = this.connections.find(item => item.id === change.id);
                }

                change.fields.forEach((field, index) => {
                    connection[field] = change.prevValues[index];
                });

                if (change.action === 'add')
                    this.connections.push(connection);
            }
        }
    }

}