const { describe, it } = require('mocha');
const { expect } = require('chai');
const RateLimiterMemory = require('../lib/RateLimiterMemory');
const BurstyLimiter = require('../lib/BurstyRateLimiter');
const RateLimiterQueue = require('../lib/RateLimiterQueue');
const RateLimiterQueueError = require('../lib/component/RateLimiterQueueError');

describe('RateLimiterQueue with FIFO queue', function RateLimiterQueueTest() {
  this.timeout(5000);

  it('remove 1 token works and 1 remaining', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 2, duration: 1 });
    const rlQueue = new RateLimiterQueue(rlMemory);
    rlQueue.removeTokens(1)
      .then((remainingTokens) => {
        expect(remainingTokens).to.equal(1);
        done();
      });
  });

  it('remove 2 tokens from bursty limiter and returns correct remainingTokens 0', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 1, duration: 1 });
    const blMemory = new RateLimiterMemory({ points: 1, duration: 3 });
    const burstyLimiter = new BurstyLimiter(rlMemory, blMemory);
    const rlQueue = new RateLimiterQueue(burstyLimiter);
    const startTime = Date.now();
    rlQueue.removeTokens(1)
      .then((remainingTokens1) => {
        expect(remainingTokens1).to.equal(0);
        rlQueue.removeTokens(1)
          .then((remainingTokens2) => {
            expect(remainingTokens2).to.equal(0);
            expect(Date.now() - startTime < 1000).to.equal(true);
            done();
          });
      });
  });

  it('remove 2 tokens from bursty limiter and wait 1 more', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 1, duration: 1 });
    const blMemory = new RateLimiterMemory({ points: 1, duration: 3 });
    const burstyLimiter = new BurstyLimiter(rlMemory, blMemory);
    const rlQueue = new RateLimiterQueue(burstyLimiter);
    const startTime = Date.now();
    rlQueue.removeTokens(1)
      .then(() => {
        rlQueue.removeTokens(1)
          .then(() => {
            rlQueue.removeTokens(1)
              .then((remainingTokens) => {
                expect(remainingTokens).to.equal(0);
                expect(Date.now() - startTime > 1000).to.equal(true);
                done();
              });
          });
      });
  });

  it('remove all tokens works and 0 remaining', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 2, duration: 1 });
    const rlQueue = new RateLimiterQueue(rlMemory);
    rlQueue.removeTokens(2)
      .then((remainingTokens) => {
        expect(remainingTokens).to.equal(0);
        done();
      });
  });

  it('return error if try to remove more tokens than allowed', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 2, duration: 1 });
    const rlQueue = new RateLimiterQueue(rlMemory);
    rlQueue.removeTokens(3)
      .then(() => {
      })
      .catch((err) => {
        expect(err instanceof RateLimiterQueueError).to.equal(true);
        done();
      });
  });

  it('queues 1 request and fire it after 1 second', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 1, duration: 1 });
    const rlQueue = new RateLimiterQueue(rlMemory);
    const time = Date.now();
    rlQueue.removeTokens(1).then(() => {
    });
    rlQueue.removeTokens(1).then((remainingTokens) => {
      expect(remainingTokens).to.equal(0);
      expect(Date.now() - time >= 1000).to.equal(true);
      done();
    });
  });

  it('respects order of queued callbacks', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 1, duration: 1 });
    const rlQueue = new RateLimiterQueue(rlMemory);
    let index;
    rlQueue.removeTokens(1).then(() => {
      index = 0;
    });
    rlQueue.removeTokens(1).then(() => {
      expect(index).to.equal(0);
      index = 1;
    });
    rlQueue.removeTokens(1).then(() => {
      expect(index).to.equal(1);
      index = 2;
    });
    rlQueue.removeTokens(1).then(() => {
      expect(index).to.equal(2);
      done();
    });
  });

  it('return error if queue length reaches maximum', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 1, duration: 1 });
    const rlQueue = new RateLimiterQueue(rlMemory, { maxQueueSize: 1 });
    rlQueue.removeTokens(1).then(() => {
    });
    rlQueue.removeTokens(1).then(() => {
      done();
    });
    rlQueue.removeTokens(1)
      .then(() => {
        done(new Error('must not allow to queue'));
      })
      .catch((err) => {
        expect(err instanceof RateLimiterQueueError).to.equal(true);
      });
  });

  it('getTokensRemaining works', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 2, duration: 1 });
    const rlQueue = new RateLimiterQueue(rlMemory);
    rlQueue.removeTokens(1)
      .then(() => {
        rlQueue.getTokensRemaining()
          .then((tokensRemaining) => {
            expect(tokensRemaining).to.equal(1);
            done();
          });
      });
  });

  it('getTokensRemaining returns maximum if internal limiter by key does not exist', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 23, duration: 1 });
    const rlQueue = new RateLimiterQueue(rlMemory);
    rlQueue.getTokensRemaining('test')
      .then((tokensRemaining) => {
        expect(tokensRemaining).to.equal(23);
        done();
      });
  });

  it('creates internal instance by key and removes tokens from it', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 2, duration: 1 });
    const rlQueue = new RateLimiterQueue(rlMemory);
    rlQueue.removeTokens(1, 'customkey')
      .then((remainingTokens) => {
        expect(remainingTokens).to.equal(1);
        rlQueue.getTokensRemaining()
          .then((defaultTokensRemaining) => {
            expect(defaultTokensRemaining).to.equal(2);
            done();
          });
      });
  });

  it('getTokensRemaining returns maximum if internal limiter does not have data', (done) => {
    const rlMemory = new RateLimiterMemory({ points: 23, duration: 1 });
    const rlQueue = new RateLimiterQueue(rlMemory);
    rlQueue.removeTokens(1, 'nodata')
      .then(() => {
        setTimeout(() => {
          rlQueue.getTokensRemaining('nodata')
            .then((tokensRemaining) => {
              expect(tokensRemaining).to.equal(23);
              done();
            });
        }, 1001)
      })
  });
});