'use strict';

const common = require('../common');
const assert = require('assert');
const fs = require('fs');
const tmpdir = require('../common/tmpdir');

tmpdir.refresh();

const expected = 'ümlaut. Лорем 運務ホソモ指及 आपको करने विकास 紙読決多密所 أضف';

let cnt = 0;
const getFileName = () => tmpdir.resolve(`readv_${++cnt}.txt`);
const exptectedBuff = Buffer.from(expected);

const allocateEmptyBuffers = (combinedLength) => {
  const bufferArr = [];
  // Allocate two buffers, each half the size of exptectedBuff
  bufferArr[0] = Buffer.alloc(Math.floor(combinedLength / 2));
  bufferArr[1] = Buffer.alloc(combinedLength - bufferArr[0].length);

  return bufferArr;
};

const getCallback = (fd, bufferArr) => {
  return common.mustSucceed((bytesRead, buffers) => {
    assert.deepStrictEqual(bufferArr, buffers);
    const expectedLength = exptectedBuff.length;
    assert.deepStrictEqual(bytesRead, expectedLength);
    fs.closeSync(fd);

    assert(Buffer.concat(bufferArr).equals(exptectedBuff));
  });
};

// fs.readv with array of buffers with all parameters
{
  const filename = getFileName();
  const fd = fs.openSync(filename, 'w+');
  fs.writeSync(fd, exptectedBuff);

  const bufferArr = allocateEmptyBuffers(exptectedBuff.length);
  const callback = getCallback(fd, bufferArr);

  fs.readv(fd, bufferArr, 0, callback);
}

// fs.readv with array of buffers without position
{
  const filename = getFileName();
  fs.writeFileSync(filename, exptectedBuff);
  const fd = fs.openSync(filename, 'r');

  const bufferArr = allocateEmptyBuffers(exptectedBuff.length);
  const callback = getCallback(fd, bufferArr);

  fs.readv(fd, bufferArr, callback);
}

/**
 * Testing with incorrect arguments
 */
const wrongInputs = [false, 'test', {}, [{}], ['sdf'], null, undefined];

{
  const filename = getFileName(2);
  fs.writeFileSync(filename, exptectedBuff);
  const fd = fs.openSync(filename, 'r');

  for (const wrongInput of wrongInputs) {
    assert.throws(
      () => fs.readv(fd, wrongInput, null, common.mustNotCall()), {
        code: 'ERR_INVALID_ARG_TYPE',
        name: 'TypeError'
      }
    );
  }

  fs.closeSync(fd);
}

{
  // fs.readv with wrong fd argument
  for (const wrongInput of wrongInputs) {
    assert.throws(
      () => fs.readv(wrongInput, common.mustNotCall()),
      {
        code: 'ERR_INVALID_ARG_TYPE',
        name: 'TypeError'
      }
    );
  }
}