import * as plugins from './npmextra.plugins.js';
import * as paths from './npmextra.paths.js';

import { Task } from '@push.rocks/taskbuffer';

export type TKeyValueStore = 'custom' | 'userHomeDir' | 'ephemeral';

export interface IKvStoreConstructorOptions<T> {
  typeArg: TKeyValueStore;
  identityArg: string;
  customPath?: string;
  mandatoryKeys?: Array<keyof T>;
}

/**
 * kvStore is a simple key value store to store data about projects between runs
 */
export class KeyValueStore<T = any> {
  private dataObject: Partial<T> = {};
  private deletedObject: Partial<T> = {};
  private mandatoryKeys: Set<keyof T> = new Set();
  public changeSubject = new plugins.smartrx.rxjs.Subject<Partial<T>>();

  private storedStateString: string = '';
  public syncTask = new Task({
    name: 'syncTask',
    buffered: true,
    bufferMax: 1,
    execDelay: 0,
    taskFunction: async () => {
      if (this.type !== 'ephemeral') {
        this.dataObject = {
          ...plugins.smartfile.fs.toObjectSync(this.filePath),
          ...this.dataObject,
        };
        for (const key of Object.keys(this.deletedObject) as Array<keyof T>) {
          delete this.dataObject[key];
        }
        this.deletedObject = {};
        await plugins.smartfile.memory.toFs(
          plugins.smartjson.stringifyPretty(this.dataObject),
          this.filePath
        );
      }
      const newStateString = plugins.smartjson.stringify(this.dataObject);

      // change detection
      if (newStateString !== this.storedStateString) {
        this.storedStateString = newStateString;
        this.changeSubject.next(this.dataObject);
      }
    },
  });

  /**
   * computes the identity and filePath
   */
  private initFilePath = () => {
    if (this.type === 'ephemeral') {
      // No file path is needed for ephemeral type
      return;
    }
    if (this.customPath) {
      // Use custom path if provided
      const absolutePath = plugins.smartpath.transform.makeAbsolute(this.customPath, paths.cwd);
      this.filePath = absolutePath;
      if (plugins.smartfile.fs.isDirectorySync(this.filePath)) {
        this.filePath = plugins.path.join(this.filePath, this.identity + '.json');
      }
      plugins.smartfile.fs.ensureFileSync(this.filePath, '{}');
      return;
    }

    let baseDir: string;
    if (this.type === 'userHomeDir') {
      baseDir = paths.kvUserHomeDirBase;
    } else {
      throw new Error('kv type not supported');
    }
    this.filePath = plugins.path.join(baseDir, this.identity + '.json');
    plugins.smartfile.fs.ensureDirSync(baseDir);
    plugins.smartfile.fs.ensureFileSync(this.filePath, '{}');
  };

  // if no custom path is provided, try to store at home directory
  public type: TKeyValueStore;
  public identity: string;
  public filePath?: string;
  private customPath?: string; // Optionally allow custom path

  /**
   * the constructor of keyvalue store
   * @param typeArg
   * @param identityArg
   * @param customPath Optional custom path for the keyValue store
   */
  constructor(optionsArg: IKvStoreConstructorOptions<T>) {
    if (optionsArg.customPath && optionsArg.typeArg !== 'custom') {
      throw new Error('customPath can only be provided if typeArg is custom');
    }
    if (optionsArg.typeArg === 'custom' && !optionsArg.customPath) {
      throw new Error('customPath must be provided if typeArg is custom');
    }
    this.type = optionsArg.typeArg;
    this.identity = optionsArg.identityArg;
    this.customPath = optionsArg.customPath; // Store custom path if provided
    this.initFilePath();
    if (optionsArg.mandatoryKeys) {
      this.setMandatoryKeys(optionsArg.mandatoryKeys);
    }
  }

  /**
   * reads all keyValue pairs at once and returns them
   */
  public async readAll(): Promise<Partial<T>> {
    await this.syncTask.trigger();
    return this.dataObject;
  }

  /**
   * reads a keyValueFile from disk
   */
  public async readKey<K extends keyof T>(keyArg: K): Promise<T[K]> {
    await this.syncTask.trigger();
    return this.dataObject[keyArg] as T[K];
  }

  /**
   * writes a specific key to the keyValueStore
   */
  public async writeKey<K extends keyof T>(keyArg: K, valueArg: T[K]): Promise<void> {
    await this.writeAll({
      [keyArg]: valueArg,
    } as unknown as Partial<T>);
  }

  public async deleteKey<K extends keyof T>(keyArg: K): Promise<void> {
    this.deletedObject[keyArg] = this.dataObject[keyArg];
    await this.syncTask.trigger();
  }

  /**
   * writes all keyValue pairs in the object argument
   */
  public async writeAll(keyValueObject: Partial<T>): Promise<void> {
    this.dataObject = { ...this.dataObject, ...keyValueObject };
    await this.syncTask.trigger();
  }

  /**
   * wipes a key value store from disk
   */
  public async wipe(): Promise<void> {
    this.dataObject = {};
    if (this.type !== 'ephemeral') {
      await plugins.smartfile.fs.remove(this.filePath);
    }
  }

  /**
   * resets the KeyValueStore to the initial state by syncing first, deleting all keys, and then triggering a sync again
   */
  public async reset(): Promise<void> {
    await this.syncTask.trigger(); // Sync to get the latest state

    // Delete all keys from the dataObject and add them to deletedObject
    for (const key of Object.keys(this.dataObject) as Array<keyof T>) {
      this.deletedObject[key] = this.dataObject[key];
      delete this.dataObject[key];
    }

    await this.syncTask.trigger(); // Sync again to reflect the deletion
  }

  private setMandatoryKeys(keys: Array<keyof T>) {
    keys.forEach(key => this.mandatoryKeys.add(key));
  }

  public async getMissingMandatoryKeys(): Promise<Array<keyof T>> {
    await this.readAll();
    return Array.from(this.mandatoryKeys).filter(key => !(key in this.dataObject));
  }

  public async waitForKeysPresent<K extends keyof T>(keysArg: K[]): Promise<void> {
    const missingKeys = keysArg.filter(keyArg => !this.dataObject[keyArg]);
    if (missingKeys.length === 0) {
      return;
    }
    return new Promise<void>((resolve, reject) => {
      const subscription = this.changeSubject.subscribe(() => {
        const missingKeys = keysArg.filter(keyArg => !this.dataObject[keyArg]);
        if (missingKeys.length === 0) {
          subscription.unsubscribe();
          resolve();
        }
      });
    });
  }

  public async waitForAndGetKey<K extends keyof T>(keyArg: K): Promise<T[K] | undefined> {
    await this.waitForKeysPresent([keyArg]);
    return this.readKey(keyArg);
  }
}