import { observable, action, runInAction } from 'mobx';
import { Without } from '../../Utils';

function getBatchName(target: any, key: string | symbol): string {
    const keyName = key.toString();
    if (target && target.constructor && target.constructor.name) {
        return `${target.constructor.name}.${keyName}`;
    }
    return keyName;
}

function propertyDecorator(target: any, key: string | symbol) {
    Object.defineProperty(target, key, {
        configurable: true,
        enumerable: false,
        get: function () {
            return 5;
        },
        set: function (value: any) {
            Object.defineProperty(this, key, {
                enumerable: false,
                writable: true,
                configurable: true,
                value: function (...args: any[]) {
                    const batch = UndoManager.StartBatch(getBatchName(target, key));
                    try {
                        return value.apply(this, args);
                    } finally {
                        batch.end();
                    }
                },
            });
        },
    });
}

export function undoBatch(target: any, key: string | symbol, descriptor?: TypedPropertyDescriptor<any>): any;
export function undoBatch(fn: (...args: any[]) => any): (...args: any[]) => any;
export function undoBatch(target: any, key?: string | symbol, descriptor?: TypedPropertyDescriptor<any>): any {
    if (!key) {
        return function () {
            const batch = UndoManager.StartBatch('');
            try {
                return target.apply(undefined, arguments);
            } finally {
                batch.end();
            }
        };
    }
    if (!descriptor) {
        propertyDecorator(target, key);
        return;
    }
    const oldFunction = descriptor.value;

    descriptor.value = function (...args: any[]) {
        const batch = UndoManager.StartBatch(getBatchName(target, key));
        try {
            return oldFunction.apply(this, args);
        } finally {
            batch.end();
        }
    };

    return descriptor;
}

export namespace UndoManager {
    export interface UndoEvent {
        undo: () => void;
        redo: () => void;
        prop: string;
    }
    type UndoBatch = UndoEvent[];

    export let undoStack: UndoBatch[] = observable([]);
    export let redoStack: UndoBatch[] = observable([]);
    let currentBatch: UndoBatch | undefined;
    export let batchCounter = 0;
    let undoing = false;
    let tempEvents: UndoEvent[] | undefined = undefined;

    export function AddEvent(event: UndoEvent): void {
        if (currentBatch && batchCounter && !undoing) {
            currentBatch.push(event);
            tempEvents?.push(event);
        }
    }

    export function CanUndo(): boolean {
        return undoStack.length > 0;
    }

    export function CanRedo(): boolean {
        return redoStack.length > 0;
    }

    export function PrintBatches(): void {
        console.log('Open Undo Batches:');
        GetOpenBatches().forEach(batch => console.log(batch.batchName));
    }

    const openBatches: Batch[] = [];
    export function GetOpenBatches(): Without<Batch, 'end'>[] {
        return openBatches;
    }
    export function FilterBatches(fieldTypes: string[]) {
        const fieldCounts: { [key: string]: number } = {};
        const lastStack = UndoManager.undoStack.slice(-1)[0]; //.lastElement();
        if (lastStack) {
            lastStack.forEach(ev => fieldTypes.includes(ev.prop) && (fieldCounts[ev.prop] = (fieldCounts[ev.prop] || 0) + 1));
            const fieldCount2: { [key: string]: number } = {};
            runInAction(
                () =>
                    (UndoManager.undoStack[UndoManager.undoStack.length - 1] = lastStack.filter(ev => {
                        if (fieldTypes.includes(ev.prop)) {
                            fieldCount2[ev.prop] = (fieldCount2[ev.prop] || 0) + 1;
                            if (fieldCount2[ev.prop] === 1 || fieldCount2[ev.prop] === fieldCounts[ev.prop]) return true;
                            return false;
                        }
                        return true;
                    }))
            );
        }
    }
    export function TraceOpenBatches() {
        console.log(`Open batches:\n\t${openBatches.map(batch => batch.batchName).join('\n\t')}\n`);
    }
    export class Batch {
        private disposed: boolean = false;

        constructor(readonly batchName: string) {
            openBatches.push(this);
        }

        private dispose = (cancel: boolean) => {
            if (this.disposed) {
                throw new Error('Cannot dispose an already disposed batch');
            }
            this.disposed = true;
            openBatches.splice(openBatches.indexOf(this));
            return EndBatch(cancel);
        };

        end = () => this.dispose(false);
        cancel = () => this.dispose(true);
    }

    export function StartBatch(batchName: string): Batch {
        // console.log("Start " + batchCounter + " " + batchName);
        batchCounter++;
        if (batchCounter > 0 && currentBatch === undefined) {
            currentBatch = [];
        }
        return new Batch(batchName);
    }

    const EndBatch = action((cancel: boolean = false) => {
        batchCounter--;
        // console.log("End " + batchCounter);
        if (batchCounter === 0 && currentBatch?.length) {
            // console.log("------ended----")
            if (!cancel) {
                undoStack.push(currentBatch);
            }
            redoStack.length = 0;
            currentBatch = undefined;
            return true;
        }
        return false;
    });

    export function RunInTempBatch<T>(fn: () => T) {
        tempEvents = [];
        try {
            const success = runInAction(fn);
            if (!success) UndoManager.UndoTempBatch();
            return success;
        } finally {
            tempEvents = undefined;
        }
    }
    //TODO Make this return the return value
    export function RunInBatch<T>(fn: () => T, batchName: string) {
        const batch = StartBatch(batchName);
        try {
            return runInAction(fn);
        } finally {
            batch.end();
        }
    }
    export const UndoTempBatch = action(() => {
        if (tempEvents) {
            undoing = true;
            for (let i = tempEvents.length - 1; i >= 0; i--) {
                tempEvents[i].undo();
            }
            undoing = false;
        }
        tempEvents = undefined;
    });
    export const Undo = action(() => {
        if (undoStack.length === 0) {
            return;
        }

        const commands = undoStack.pop();
        if (!commands) {
            return;
        }

        undoing = true;
        for (let i = commands.length - 1; i >= 0; i--) {
            commands[i].undo();
        }
        undoing = false;

        redoStack.push(commands);
    });

    export const Redo = action(() => {
        if (redoStack.length === 0) {
            return;
        }

        const commands = redoStack.pop();
        if (!commands) {
            return;
        }

        undoing = true;
        for (const command of commands) {
            command.redo();
        }
        undoing = false;

        undoStack.push(commands);
    });
}