import { describe, expect, it } from "bun:test";
import { withoutAggressiveGC } from "gc";
var { StringDecoder } = require("string_decoder");

it("require('string_decoder')", async () => {
  expect((await import("string_decoder")).StringDecoder).toBe(StringDecoder);
});

it("StringDecoder-utf8", () => {
  test("utf-8", Buffer.from("$", "utf-8"), "$");
  test("utf-8", Buffer.from("¢", "utf-8"), "¢");
  test("utf-8", Buffer.from("€", "utf-8"), "€");
  test("utf-8", Buffer.from("𤭢", "utf-8"), "𤭢");
  // A mixed ascii and non-ascii string
  // Test stolen from deps/v8/test/cctest/test-strings.cc
  // U+02E4 -> CB A4
  // U+0064 -> 64
  // U+12E4 -> E1 8B A4
  // U+0030 -> 30
  // U+3045 -> E3 81 85
  test(
    "utf-8",
    Buffer.from([0xcb, 0xa4, 0x64, 0xe1, 0x8b, 0xa4, 0x30, 0xe3, 0x81, 0x85]),
    "\u02e4\u0064\u12e4\u0030\u3045",
  );
});

it("StringDecoder-ucs-2", () => {
  test("ucs2", Buffer.from("ababc", "ucs2"), "ababc");
});

it("StringDecoder-utf16le", () => {
  test("utf16le", Buffer.from("3DD84DDC", "hex"), "\ud83d\udc4d");
});

it("StringDecoder-utf8-additional", () => {
  let decoder = new StringDecoder("utf8");
  expect(decoder.write(Buffer.from("E18B", "hex"))).toBe("");
  expect(decoder.end()).toBe("\ufffd");

  decoder = new StringDecoder("utf8");
  expect(decoder.write(Buffer.from("\ufffd"))).toBe("\ufffd");
  expect(decoder.end()).toBe("");

  decoder = new StringDecoder("utf8");
  expect(decoder.write(Buffer.from("\ufffd\ufffd\ufffd"))).toBe(
    "\ufffd\ufffd\ufffd",
  );
  expect(decoder.end()).toBe("");

  decoder = new StringDecoder("utf8");
  expect(decoder.write(Buffer.from("EFBFBDE2", "hex"))).toBe("\ufffd");
  expect(decoder.end()).toBe("\ufffd");

  decoder = new StringDecoder("utf8");
  expect(decoder.write(Buffer.from("F1", "hex"))).toBe("");
  expect(decoder.write(Buffer.from("41F2", "hex"))).toBe("\ufffdA");
  expect(decoder.end()).toBe("\ufffd");

  // Additional utf8Text test
  decoder = new StringDecoder("utf8");
  expect(decoder.text(Buffer.from([0x41]), 2)).toBe("");
});

it("StringDecoder-utf16le-additional", () => {
  // Additional UTF-16LE surrogate pair tests
  let decoder = new StringDecoder("utf16le");
  expect(decoder.write(Buffer.from("3DD8", "hex"))).toBe("");
  expect(decoder.write(Buffer.from("4D", "hex"))).toBe("");
  expect(decoder.write(Buffer.from("DC", "hex"))).toBe("\ud83d\udc4d");
  expect(decoder.end()).toBe("");

  decoder = new StringDecoder("utf16le");
  expect(decoder.write(Buffer.from("3DD8", "hex"))).toBe("");
  expect(decoder.end()).toBe("\ud83d");

  decoder = new StringDecoder("utf16le");
  expect(decoder.write(Buffer.from("3DD8", "hex"))).toBe("");
  expect(decoder.write(Buffer.from("4D", "hex"))).toBe("");
  expect(decoder.end()).toBe("\ud83d");

  decoder = new StringDecoder("utf16le");
  expect(decoder.write(Buffer.from("3DD84D", "hex"))).toBe("\ud83d");
  expect(decoder.end()).toBe("");
});

// Test verifies that StringDecoder will correctly decode the given input
// buffer with the given encoding to the expected output. It will attempt all
// possible ways to write() the input buffer, see writeSequences(). The
// singleSequence allows for easy debugging of a specific sequence which is
// useful in case of test failures.
function test(encoding, input, expected, singleSequence) {
  withoutAggressiveGC(() => {
    let sequences;
    if (!singleSequence) {
      sequences = writeSequences(input.length);
    } else {
      sequences = [singleSequence];
    }
    sequences.forEach((sequence) => {
      const decoder = new StringDecoder(encoding);
      let output = "";
      sequence.forEach((write) => {
        output += decoder.write(input.slice(write[0], write[1]));
      });
      output += decoder.end();
      expect(output).toBe(expected);
    });
  });
}

// writeSequences returns an array of arrays that describes all possible ways a
// buffer of the given length could be split up and passed to sequential write
// calls.
//
// e.G. writeSequences(3) will return: [
//   [ [ 0, 3 ] ],
//   [ [ 0, 2 ], [ 2, 3 ] ],
//   [ [ 0, 1 ], [ 1, 3 ] ],
//   [ [ 0, 1 ], [ 1, 2 ], [ 2, 3 ] ]
// ]
function writeSequences(length, start, sequence) {
  if (start === undefined) {
    start = 0;
    sequence = [];
  } else if (start === length) {
    return [sequence];
  }
  let sequences = [];
  for (let end = length; end > start; end--) {
    const subSequence = sequence.concat([[start, end]]);
    const subSequences = writeSequences(length, end, subSequence, sequences);
    sequences = sequences.concat(subSequences);
  }
  return sequences;
}

describe("StringDecoder.end", () => {
  const encodings = ["base64", "base64url", "hex", "utf8", "utf16le", "ucs2"];

  const bufs = ["☃💩", "asdf"].map((b) => Buffer.from(b));

  // Also test just arbitrary bytes from 0-15.
  for (let i = 1; i <= 16; i++) {
    const bytes = "."
      .repeat(i - 1)
      .split(".")
      .map((_, j) => j + 0x78);
    bufs.push(Buffer.from(bytes));
  }

  encodings.forEach(testEncoding);

  testEnd("utf8", Buffer.of(0xe2), Buffer.of(0x61), "\uFFFDa");
  testEnd("utf8", Buffer.of(0xe2), Buffer.of(0x82), "\uFFFD\uFFFD");
  testEnd("utf8", Buffer.of(0xe2), Buffer.of(0xe2), "\uFFFD\uFFFD");
  testEnd("utf8", Buffer.of(0xe2, 0x82), Buffer.of(0x61), "\uFFFDa");
  testEnd("utf8", Buffer.of(0xe2, 0x82), Buffer.of(0xac), "\uFFFD\uFFFD");
  testEnd("utf8", Buffer.of(0xe2, 0x82), Buffer.of(0xe2), "\uFFFD\uFFFD");
  testEnd("utf8", Buffer.of(0xe2, 0x82, 0xac), Buffer.of(0x61), "€a");

  testEnd("utf16le", Buffer.of(0x3d), Buffer.of(0x61, 0x00), "a");
  testEnd("utf16le", Buffer.of(0x3d), Buffer.of(0xd8, 0x4d, 0xdc), "\u4DD8");
  testEnd("utf16le", Buffer.of(0x3d, 0xd8), Buffer.of(), "\uD83D");
  testEnd("utf16le", Buffer.of(0x3d, 0xd8), Buffer.of(0x61, 0x00), "\uD83Da");
  testEnd(
    "utf16le",
    Buffer.of(0x3d, 0xd8),
    Buffer.of(0x4d, 0xdc),
    "\uD83D\uDC4D",
  );
  testEnd("utf16le", Buffer.of(0x3d, 0xd8, 0x4d), Buffer.of(), "\uD83D");
  testEnd(
    "utf16le",
    Buffer.of(0x3d, 0xd8, 0x4d),
    Buffer.of(0x61, 0x00),
    "\uD83Da",
  );
  testEnd("utf16le", Buffer.of(0x3d, 0xd8, 0x4d), Buffer.of(0xdc), "\uD83D");
  testEnd(
    "utf16le",
    Buffer.of(0x3d, 0xd8, 0x4d, 0xdc),
    Buffer.of(0x61, 0x00),
    "👍a",
  );

  testEnd("base64", Buffer.of(0x61), Buffer.of(), "YQ==");
  testEnd("base64", Buffer.of(0x61), Buffer.of(0x61), "YQ==YQ==");
  testEnd("base64", Buffer.of(0x61, 0x61), Buffer.of(), "YWE=");
  testEnd("base64", Buffer.of(0x61, 0x61), Buffer.of(0x61), "YWE=YQ==");
  testEnd("base64", Buffer.of(0x61, 0x61, 0x61), Buffer.of(), "YWFh");
  testEnd("base64", Buffer.of(0x61, 0x61, 0x61), Buffer.of(0x61), "YWFhYQ==");

  testEnd("base64url", Buffer.of(0x61), Buffer.of(), "YQ");
  testEnd("base64url", Buffer.of(0x61), Buffer.of(0x61), "YQYQ");
  testEnd("base64url", Buffer.of(0x61, 0x61), Buffer.of(), "YWE");
  testEnd("base64url", Buffer.of(0x61, 0x61), Buffer.of(0x61), "YWEYQ");
  testEnd("base64url", Buffer.of(0x61, 0x61, 0x61), Buffer.of(), "YWFh");
  testEnd("base64url", Buffer.of(0x61, 0x61, 0x61), Buffer.of(0x61), "YWFhYQ");

  function testEncoding(encoding) {
    it(encoding + " testbuf", () => {
      bufs.forEach((buf) => {
        testBuf(encoding, buf);
      });
    });
  }

  function testBuf(encoding, buf) {
    // Write one byte at a time.
    let s = new StringDecoder(encoding);
    let res1 = "";
    for (let i = 0; i < buf.length; i++) {
      res1 += s.write(buf.slice(i, i + 1));
    }
    res1 += s.end();

    // Write the whole buffer at once.
    let res2 = "";
    s = new StringDecoder(encoding);
    res2 += s.write(buf);
    res2 += s.end();

    // .toString() on the buffer
    const res3 = buf.toString(encoding);

    // One byte at a time should match toString
    expect(res1).toEqual(res3);
    // All bytes at once should match toString
    expect(res2).toEqual(res3);
  }

  function testEnd(encoding, incomplete, next, expected) {
    it(`${encoding} partial ${JSON.stringify(expected)}`, () => {
      let res = "";
      const s = new StringDecoder(encoding);
      res += s.write(incomplete);
      res += s.end();
      res += s.write(next);
      res += s.end();

      expect(res).toEqual(expected);
    });
  }
});