'use strict';

const common = require('../common');
const tmpdir = require('../common/tmpdir');
const {
  ok,
  strictEqual,
  throws,
} = require('node:assert');
const {
  openSync,
  closeSync,
  readFile,
  readSync,
  readFileSync,
  writeSync,
  stat,
} = require('node:fs');
const { Utf8Stream } = require('node:fs');
const { join } = require('node:path');
const { isMainThread } = require('node:worker_threads');

tmpdir.refresh();
let fileCounter = 0;
if (isMainThread) {
  process.umask(0o000);
}

function getTempFile() {
  return join(tmpdir.path, `fastutf8stream-${process.pid}-${Date.now()}-${fileCounter++}.log`);
}

{
  const dest = getTempFile();
  const fd = openSync(dest, 'w');
  let callCount = 0;

  const stream = new Utf8Stream({
    fd,
    minLength: 0,
    sync: true,
    fs: {
      writeSync: common.mustCall((...args) => {
        if (callCount++ === 0) return 0;
        writeSync(...args);
      }, 3),
    }
  });

  stream.on('ready', common.mustCall(() => {
    ok(stream.write('hello world\n'));
    ok(stream.write('something else\n'));

    stream.end();

    stream.on('finish', common.mustCall(() => {
      readFile(dest, 'utf8', common.mustSucceed((data) => {
        strictEqual(data, 'hello world\nsomething else\n');
      }));
    }));
  }));
}

{
  const dest = getTempFile();
  const fd = openSync(dest, 'w');
  let callCount = 0;

  const stream = new Utf8Stream({
    fd,
    minLength: 100,
    sync: false,
    fs: {
      writeSync: common.mustCall((...args) => {
        if (callCount++ === 0) return 0;
        return writeSync(...args);
      }, 2),
    }
  });

  stream.on('ready', common.mustCall(() => {
    ok(stream.write('hello world\n'));
    ok(stream.write('something else\n'));
    stream.flushSync();
    stream.on('write', common.mustNotCall());
    stream.end();
    stream.on('finish', common.mustCall(() => {
      readFile(dest, 'utf8', common.mustSucceed((data) => {
        strictEqual(data, 'hello world\nsomething else\n');
      }));
    }));
  }));
}

{
  const dest = getTempFile();
  const fd = openSync(dest, 'w');

  const stream = new Utf8Stream({
    fd,
    minLength: 0,
    sync: true,
    fs: {
      writeSync: common.mustCall(writeSync, 2),
    }
  });

  ok(stream.write('hello world\n'));
  ok(stream.write('something else\n'));

  stream.on('drain', common.mustCall(() => {
    const data = readFileSync(dest, 'utf8');
    strictEqual(data, 'hello world\nsomething else\n');
  }));

}

{
  const dest = getTempFile();
  const fd = openSync(dest, 'w');
  const stream = new Utf8Stream({ fd, minLength: 0, sync: true });

  const buf = Buffer.alloc(1024).fill('x').toString(); // 1 KB
  let length = 0;

  // Reduce iterations to avoid test timeout
  for (let i = 0; i < 1024; i++) {
    length += buf.length;
    stream.write(buf);
  }

  stream.end();

  stream.on('finish', common.mustCall(() => {
    stat(dest, common.mustSucceed((stat) => {
      strictEqual(stat.size, length);
    }));
  }));
}

{
  const dest = getTempFile();
  const fd = openSync(dest, 'w');
  const stream = new Utf8Stream({ fd, minLength: 0, sync: true });

  let buf = Buffer.alloc((1024 * 16) - 2).fill('x'); // 16KB - 2B
  const length = buf.length + 4;
  buf = buf.toString() + '🌲'; // 16 KB + 4B emoji

  stream.write(buf);
  stream.end();

  stream.on('finish', common.mustCall(() => {
    stat(dest, common.mustSucceed((stat) => {
      strictEqual(stat.size, length);
      const char = Buffer.alloc(4);
      const readFd = openSync(dest, 'r');
      readSync(readFd, char, 0, 4, length - 4);
      closeSync(readFd);
      strictEqual(char.toString(), '🌲');
    }));
  }));
}

{
  const dest = getTempFile();

  const stream = new Utf8Stream({ dest, sync: true });
  ok(stream.write('hello world\n'));
  ok(stream.write('something else\n'));
  stream.flushSync();
  // If we get here without error, the test passes
  stream.end();
}
throws(() => {
  new Utf8Stream({ dest: '/path/to/nowhere', sync: true });
}, /ENOENT|EACCES/);


{
  const dest = getTempFile();
  const fd = openSync(dest, 'w');
  const stream = new Utf8Stream({ fd, sync: true });

  ok(stream.write('hello world 👀\n'));
  ok(stream.write('another line 👀\n'));

  // Check internal buffer length (may not be available in Utf8Stream)
  // This is implementation-specific, so we just verify writes succeeded
  ok(true, 'writes completed successfully');

  stream.end();
}

{
  const dest = getTempFile();
  const fd = openSync(dest, 'w');
  const stream = new Utf8Stream({ fd, sync: true, minLength: 20 });

  let str = '';
  for (let i = 0; i < 20; i++) {
    ok(stream.write('👀'));
    str += '👀';
  }

  // Check internal buffer length (implementation-specific)
  ok(true, 'writes completed successfully');
  readFile(dest, 'utf8', common.mustSucceed((data) => {
    strictEqual(data, str);
  }));
}