import { isThenable } from './is.js';

/* eslint-disable @typescript-eslint/explicit-function-return-type */

/** SyncPromise internal states */
var States; (function (States) {
  /** Pending */
  const PENDING = 0; States[States["PENDING"] = PENDING] = "PENDING";
  /** Resolved / OK */
  const RESOLVED = 1; States[States["RESOLVED"] = RESOLVED] = "RESOLVED";
  /** Rejected / Error */
  const REJECTED = 2; States[States["REJECTED"] = REJECTED] = "REJECTED";
})(States || (States = {}));

// Overloads so we can call resolvedSyncPromise without arguments and generic argument

/**
 * Creates a resolved sync promise.
 *
 * @param value the value to resolve the promise with
 * @returns the resolved sync promise
 */
function resolvedSyncPromise(value) {
  return new SyncPromise(resolve => {
    resolve(value);
  });
}

/**
 * Creates a rejected sync promise.
 *
 * @param value the value to reject the promise with
 * @returns the rejected sync promise
 */
function rejectedSyncPromise(reason) {
  return new SyncPromise((_, reject) => {
    reject(reason);
  });
}

/**
 * Thenable class that behaves like a Promise and follows it's interface
 * but is not async internally
 */
class SyncPromise {

   constructor(
    executor,
  ) {SyncPromise.prototype.__init.call(this);SyncPromise.prototype.__init2.call(this);SyncPromise.prototype.__init3.call(this);SyncPromise.prototype.__init4.call(this);
    this._state = States.PENDING;
    this._handlers = [];

    try {
      executor(this._resolve, this._reject);
    } catch (e) {
      this._reject(e);
    }
  }

  /** JSDoc */
   then(
    onfulfilled,
    onrejected,
  ) {
    return new SyncPromise((resolve, reject) => {
      this._handlers.push([
        false,
        result => {
          if (!onfulfilled) {
            // TODO: ¯\_(ツ)_/¯
            // TODO: FIXME
            resolve(result );
          } else {
            try {
              resolve(onfulfilled(result));
            } catch (e) {
              reject(e);
            }
          }
        },
        reason => {
          if (!onrejected) {
            reject(reason);
          } else {
            try {
              resolve(onrejected(reason));
            } catch (e) {
              reject(e);
            }
          }
        },
      ]);
      this._executeHandlers();
    });
  }

  /** JSDoc */
   catch(
    onrejected,
  ) {
    return this.then(val => val, onrejected);
  }

  /** JSDoc */
   finally(onfinally) {
    return new SyncPromise((resolve, reject) => {
      let val;
      let isRejected;

      return this.then(
        value => {
          isRejected = false;
          val = value;
          if (onfinally) {
            onfinally();
          }
        },
        reason => {
          isRejected = true;
          val = reason;
          if (onfinally) {
            onfinally();
          }
        },
      ).then(() => {
        if (isRejected) {
          reject(val);
          return;
        }

        resolve(val );
      });
    });
  }

  /** JSDoc */
    __init() {this._resolve = (value) => {
    this._setResult(States.RESOLVED, value);
  };}

  /** JSDoc */
    __init2() {this._reject = (reason) => {
    this._setResult(States.REJECTED, reason);
  };}

  /** JSDoc */
    __init3() {this._setResult = (state, value) => {
    if (this._state !== States.PENDING) {
      return;
    }

    if (isThenable(value)) {
      void (value ).then(this._resolve, this._reject);
      return;
    }

    this._state = state;
    this._value = value;

    this._executeHandlers();
  };}

  /** JSDoc */
    __init4() {this._executeHandlers = () => {
    if (this._state === States.PENDING) {
      return;
    }

    const cachedHandlers = this._handlers.slice();
    this._handlers = [];

    cachedHandlers.forEach(handler => {
      if (handler[0]) {
        return;
      }

      if (this._state === States.RESOLVED) {
        // eslint-disable-next-line @typescript-eslint/no-floating-promises
        handler[1](this._value );
      }

      if (this._state === States.REJECTED) {
        handler[2](this._value);
      }

      handler[0] = true;
    });
  };}
}

export { SyncPromise, rejectedSyncPromise, resolvedSyncPromise };
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