import { Transaction, TransactionsBatchInfo } from './models';

/**
 * @category Utils
 */
export type UniqueArray<T> = T extends readonly [infer X, ...infer Rest]
  ? InArray<Rest, X> extends true
    ? ['Encountered value with duplicates:', X]
    : readonly [X, ...UniqueArray<Rest>]
  : T

/**
 * @category Utils
 */
export type InArray<T, X> = T extends readonly [X, ...infer _Rest]
  ? true
  : T extends readonly [X]
    ? true
    : T extends readonly [infer _, ...infer Rest]
      ? InArray<Rest, X>
      : false

/**
 * @category Utils
 */
export type ArrayItemType<T extends readonly unknown[]> = T extends readonly (infer Ts)[] ? Ts : never;

/**
 * @category Utils
 */
export class Address {
  private readonly _address: string;

  constructor(address: string) {
    this._address = address;
  }

  public toString(): string {
    return this._address;
  }

  public toJSON(): string {
    return this._address;
  }

  public equals = (other: Address | string): boolean => this._equals(other);

  private _equals(other: Address | string): boolean {
    if (typeof other === 'string') {
      return this._address === other;
    } else {
      return this._address === other?._address;
    }
  }
}

/**
 * Check whether the provider object is instance of `Address`,
 * handling the case of duplicated dependencies.
 */
export function isAddressObject(address: object | null): boolean {
  return (
    address != null &&
    (address instanceof Address ||
      Object.getPrototypeOf(address).constructor.name === Address.prototype.constructor.name)
  );
}

/**
 * @category Utils
 */
export class AddressLiteral<T extends string> extends Address {
  constructor(address: CheckAddress<T>) {
    super(address);
  }
}

/**
 * @category Utils
 */
export type CheckAddress<T extends string> = AddressImpl<T, Lowercase<T>>;

type AddressPrefix = '0:' | '-1:'
type AddressImpl<T, Tl extends string> = Tl extends `${AddressPrefix}${infer Hash}`
  ? true extends IsHexString<Hash, []>
    ? T : never
  : never;

type HexSymbol = '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' | 'a' | 'b' | 'c' | 'd' | 'e' | 'f'
type HexByte = `${HexSymbol}${HexSymbol}`
type IsHexString<T extends string, L extends readonly number[]> =
  T extends `${HexByte}${infer Tail}`
    ? IsHexString<Tail, [...L, 0]>
    : T extends '' ? L['length'] extends 32 ? true : never : never

/**
 * @category Utils
 */
export class MessageExpiredException extends Error {
  constructor(public readonly address: Address, public readonly hash: string) {
    super('Message expired');
  }
}

export class DelayedTransactions {
  private readonly transactions: Map<string, {
    promise: Promise<Transaction | undefined>,
    resolve: (transaction?: Transaction) => void,
    reject: () => void,
  }> = new Map();

  public async waitTransaction(address: Address, hash: string): Promise<Transaction> {
    let transaction = this.transactions.get(hash)?.promise;
    if (transaction == null) {
      let resolve: (transaction?: Transaction) => void;
      let reject: () => void;
      transaction = new Promise<Transaction | undefined>((promiseResolve, promiseReject) => {
        resolve = (tx) => promiseResolve(tx);
        reject = () => promiseReject();
      });
      this.transactions.set(hash, {
        promise: transaction,
        resolve: resolve!,
        reject: reject!,
      });
    }

    const tx = await transaction;
    if (tx == null) {
      throw new MessageExpiredException(address, hash);
    }
    return tx;
  }

  public fillTransaction(hash: string, transaction?: Transaction) {
    const pendingTransaction = this.transactions.get(hash);
    if (pendingTransaction != null) {
      pendingTransaction.resolve(transaction);
    } else {
      this.transactions.set(hash, {
        promise: Promise.resolve(transaction),
        resolve: () => { /* do nothing */
        },
        reject: () => { /* do nothing */
        },
      });
    }
  }
}

/**
 * @category Utils
 */
export class Semaphore {
  private tasks: (() => void)[] = [];
  count: number;

  constructor(count: number) {
    this.count = count;
  }

  public acquire(): Promise<() => void> {
    return new Promise<() => void>((res, _rej) => {
      this.tasks.push(() => {
        let released = false;
        res(() => {
          if (!released) {
            released = true;
            this.count++;
            this.sched();
          }
        });
      });
      nextTick(this.sched);
    });
  }

  public releaseAll() {
    while (this.tasks.length > 0) {
      this.tasks.shift()?.();
    }
  }

  sched = () => {
    if (this.count > 0 && this.tasks.length > 0) {
      this.count--;
      this.tasks.shift()?.();
    }
  };
}

function byObserver(Observer: any) {
  const node = document.createTextNode('');
  let queue: any, currentQueue: any, bit = 0, i = 0;
  new Observer(function() {
    let callback;
    if (!queue) {
      if (!currentQueue) return;
      queue = currentQueue;
    } else if (currentQueue) {
      queue = currentQueue.slice(i).concat(queue);
    }
    currentQueue = queue;
    queue = null;
    i = 0;
    if (typeof currentQueue === 'function') {
      callback = currentQueue;
      currentQueue = null;
      callback();
      return;
    }
    node.data = (bit = ++bit % 2) as any;
    while (i < currentQueue.length) {
      callback = currentQueue[i];
      i++;
      if (i === currentQueue.length) currentQueue = null;
      callback();
    }
  }).observe(node, { characterData: true });

  return function(fn: any) {
    if (queue) {
      if (typeof queue === 'function') queue = [queue, fn];
      else queue.push(fn);
      return;
    }
    queue = fn;
    node.data = (bit = ++bit % 2) as any;
  };
}

const nextTick = (function() {
  // queueMicrotask
  if (typeof queueMicrotask === 'function') {
    return queueMicrotask;
  }

  // MutationObserver
  if ((typeof document === 'object') && document) {
    if (typeof MutationObserver === 'function') return byObserver(MutationObserver);
    if (typeof (window as any).WebKitMutationObserver === 'function') return byObserver((window as any).WebKitMutationObserver);
  }

  /* @ts-ignore */
  if (typeof setImmediate === 'function') {
    /* @ts-ignore */
    return setImmediate;
  }

  if ((typeof setTimeout === 'function') || (typeof setTimeout === 'object')) {
    return function(cb: any) {
      setTimeout(cb, 0);
    };
  }

  throw new Error('No `nextTick` implementation found');
}());

/**
 * @category Utils
 */
export const LT_COLLATOR: Intl.Collator = new Intl.Collator(undefined, { numeric: true, sensitivity: 'base' });

/**
 * Modifies knownTransactions array, merging it with new transactions.
 * All arrays are assumed to be sorted by descending logical time.
 *
 * > Note! This method does not remove duplicates.
 *
 * @param knownTransactions
 * @param newTransactions
 * @param info
 *
 * @category Utils
 */
export function mergeTransactions<Addr>(
  knownTransactions: Transaction<Addr>[],
  newTransactions: Transaction<Addr>[],
  info: TransactionsBatchInfo,
): Transaction<Addr>[] {
  if (info.batchType === 'old') {
    knownTransactions.push(...newTransactions);
    return knownTransactions;
  }

  if (knownTransactions.length === 0) {
    knownTransactions.push(...newTransactions);
    return knownTransactions;
  }

  // Example:
  // known lts: [N, N-1, N-2, N-3, (!) N-10,...]
  // new lts: [N-4, N-5]
  // batch info: { minLt: N-5, maxLt: N-4, batchType: 'new' }

  // 1. Skip indices until known transaction lt is greater than the biggest in the batch
  let i = 0;
  while (
    i < knownTransactions.length &&
    LT_COLLATOR.compare(knownTransactions[i].id.lt, info.maxLt) >= 0
    ) {
    ++i;
  }

  // 2. Insert new transactions
  knownTransactions.splice(i, 0, ...newTransactions);
  return knownTransactions;
}

const MAX = 4294967295;

let idCounter = Math.floor(Math.random() * MAX);

export function getUniqueId(): number {
  idCounter = (idCounter + 1) % MAX;
  return idCounter;
}