import assert from "assert";
import { readFile } from "fs/promises";
import { URL } from "url";
import { describe, it } from "vitest";
import { isIdentifierContinue, isIdentifierStart } from "../src/core/charcode.js";
import { DiagnosticHandler, formatDiagnostic } from "../src/core/diagnostics.js";
import {
  KeywordLimit,
  Keywords,
  Token,
  TokenDisplay,
  createScanner,
  isKeyword,
  isPunctuation,
  isStatementKeyword,
} from "../src/core/scanner.js";
import { DiagnosticMatch, expectDiagnostics } from "../src/testing/expect.js";
import { extractSquiggles } from "../src/testing/test-server-host.js";

type TokenEntry = [
  Token,
  string?,
  {
    pos?: number;
    line?: number;
    character?: number;
    value?: string;
  }?,
];

function tokens(text: string, diagnosticHandler?: DiagnosticHandler): TokenEntry[] {
  if (!diagnosticHandler) {
    diagnosticHandler = (diagnostic) =>
      assert.fail("Unexpected diagnostic: " + formatDiagnostic(diagnostic));
  }

  const scanner = createScanner(text, diagnosticHandler);
  const result: TokenEntry[] = [];
  do {
    const token = scanner.scan();
    assert.strictEqual(token, scanner.token);
    result.push([
      scanner.token,
      scanner.getTokenText(),
      {
        pos: scanner.tokenPosition,
        value: scanner.getTokenValue(),
        ...scanner.file.getLineAndCharacterOfPosition(scanner.tokenPosition),
      },
    ]);
  } while (!scanner.eof());

  // verify that the input matches the output
  const out = result.map((each) => each[1]).join("");
  assert.strictEqual(out, text, "Input text should match parsed token values");

  return result;
}

function verify(tokens: TokenEntry[], expecting: TokenEntry[]) {
  for (const [index, [expectedToken, expectedText, expectedAdditional]] of expecting.entries()) {
    const [token, text, additional] = tokens[index];
    assert.strictEqual(Token[token], Token[expectedToken], `Token ${index} must match`);

    if (expectedText) {
      assert.strictEqual(text, expectedText, `Token ${index} test must match`);
    }

    if (expectedAdditional?.pos) {
      assert.strictEqual(
        additional!.pos,
        expectedAdditional.pos,
        `Token ${index} position must match`
      );
    }

    if (expectedAdditional?.line) {
      assert.strictEqual(
        additional!.line,
        expectedAdditional.line,
        `Token ${index} line must match`
      );
    }

    if (expectedAdditional?.character) {
      assert.strictEqual(
        additional!.character,
        expectedAdditional?.character,
        `Token ${index} character must match`
      );
    }

    if (expectedAdditional?.value) {
      assert.strictEqual(
        additional!.value,
        expectedAdditional.value,
        `Token ${index} value must match`
      );
    }
  }
}

describe("compiler: scanner", () => {
  /** verifies that we can scan tokens and get back some output. */
  it("smoketest", () => {
    const all = tokens('\tthis was "a" test');
    verify(all, [
      [Token.Whitespace],
      [Token.Identifier, "this", { value: "this" }],
      [Token.Whitespace],
      [Token.Identifier, "was", { value: "was" }],
      [Token.Whitespace],
      [Token.StringLiteral, '"a"', { value: "a" }],
      [Token.Whitespace],
      [Token.Identifier, "test", { value: "test" }],
    ]);
  });

  it("scans objects", () => {
    const all = tokens("model Foo{x:y}");

    verify(all, [
      [Token.ModelKeyword],
      [Token.Whitespace],
      [Token.Identifier, "Foo"],
      [Token.OpenBrace],
      [Token.Identifier, "x"],
      [Token.Colon],
      [Token.Identifier, "y"],
      [Token.CloseBrace],
    ]);
  });

  it("scans intersections", () => {
    const all = tokens("A&B");
    verify(all, [[Token.Identifier, "A"], [Token.Ampersand], [Token.Identifier, "B"]]);
  });

  it("scans decorator expressions", () => {
    const all = tokens('@foo(1,"hello",foo)');

    verify(all, [
      [Token.At],
      [Token.Identifier, "foo"],
      [Token.OpenParen],
      [Token.NumericLiteral, "1"],
      [Token.Comma],
      [Token.StringLiteral, '"hello"'],
      [Token.Comma],
      [Token.Identifier],
      [Token.CloseParen],
    ]);
  });

  it("scans directive expressions", () => {
    const all = tokens('#suppress foo "hello")');

    verify(all, [
      [Token.Hash],
      [Token.Identifier, "suppress"],
      [Token.Whitespace],
      [Token.Identifier],
      [Token.Whitespace],
      [Token.StringLiteral, '"hello"'],
    ]);
  });

  it("scans extends keyword", () => {
    const all = tokens("model foo extends bar{}");
    verify(all, [
      [Token.ModelKeyword],
      [Token.Whitespace],
      [Token.Identifier, "foo"],
      [Token.Whitespace],
      [Token.ExtendsKeyword],
      [Token.Whitespace],
      [Token.Identifier, "bar"],
      [Token.OpenBrace],
      [Token.CloseBrace],
    ]);
  });

  it("scans numeric literals", () => {
    const all = tokens("42 0xBEEF 0b1010 1.5e4 314.0e-2 1e+1000");
    verify(all, [
      [Token.NumericLiteral, "42"],
      [Token.Whitespace],
      [Token.NumericLiteral, "0xBEEF"],
      [Token.Whitespace],
      [Token.NumericLiteral, "0b1010"],
      [Token.Whitespace],
      [Token.NumericLiteral, "1.5e4"],
      [Token.Whitespace],
      [Token.NumericLiteral, "314.0e-2"],
      [Token.Whitespace],
      [Token.NumericLiteral, "1e+1000"],
    ]);
  });

  it("scans projection-related tokens", () => {
    const all = tokens("<= >= && || == projection if =>");
    verify(all, [
      [Token.LessThanEquals, "<="],
      [Token.Whitespace],
      [Token.GreaterThanEquals, ">="],
      [Token.Whitespace],
      [Token.AmpsersandAmpersand, "&&"],
      [Token.Whitespace],
      [Token.BarBar, "||"],
      [Token.Whitespace],
      [Token.EqualsEquals, "=="],
      [Token.Whitespace],
      [Token.ProjectionKeyword, "projection"],
      [Token.Whitespace],
      [Token.IfKeyword, "if"],
      [Token.Whitespace],
      [Token.EqualsGreaterThan, "=>"],
    ]);
  });

  function scanString(
    text: string,
    expectedValue: string,
    expectedDiagnostic?: RegExp | DiagnosticMatch
  ) {
    const scanner = createScanner(text, (diagnostic) => {
      if (expectedDiagnostic) {
        if (expectedDiagnostic instanceof RegExp) {
          assert.match(diagnostic.message, expectedDiagnostic);
        } else {
          expectDiagnostics([diagnostic], expectedDiagnostic);
        }
      } else {
        assert.fail("No diagnostic expected, but got " + formatDiagnostic(diagnostic));
      }
    });

    assert.strictEqual(scanner.scan(), Token.StringLiteral);
    assert.strictEqual(scanner.token, Token.StringLiteral);
    if (!expectedDiagnostic) {
      assert.strictEqual(scanner.getTokenText(), text);
    }
    assert.strictEqual(scanner.getTokenValue(), expectedValue);
  }

  it("scans empty strings", () => {
    scanString('""', "");
  });

  it("scans strings single-line strings with escape sequences", () => {
    scanString('"Hello world \\r\\n \\t \\" \\\\ !"', 'Hello world \r\n \t " \\ !');
  });

  it("report diagnostic when escaping invalid char", () => {
    const { source, pos, end } = extractSquiggles('"Hello world ~~~\\d~~~"');
    scanString(source, "Hello world d", {
      code: "invalid-escape-sequence",
      message: "Invalid escape sequence.",
      pos,
      end,
    });
  });

  it("does not allow multi-line, non-triple-quoted strings", () => {
    scanString('"More\r\nthan\r\none\r\nline"', "More", /Unterminated string/);
    scanString('"More\nthan\none\nline"', "More", /Unterminated string/);
  });

  it("scans triple-quoted strings", () => {
    scanString(
      // NOTE: sloppy blank line formatting and trailing whitespace after open
      //       quotes above is deliberate here and deliberately tolerated by
      //       the scanner.
      `"""   
      This is a triple-quoted string

  
      "You do not need to escape lone quotes"
      You can use escape sequences: \\r \\n \\t \\\\ \\"
      """`,
      'This is a triple-quoted string\n\n\n"You do not need to escape lone quotes"\nYou can use escape sequences: \r \n \t \\ "'
    );
  });

  it("normalizes CRLF to LF in multi-line string", () => {
    scanString('"""\r\nThis\r\nis\r\na\r\ntest\r\n"""', "This\nis\na\ntest");
  });

  it("provides token position", () => {
    const all = tokens("a x\raa x\r\naaa x\naaaa x\u{2028}aaaaa x\u{2029}aaaaaa x");
    verify(all, [
      [Token.Identifier, "a", { pos: 0, line: 0, character: 0 }],
      [Token.Whitespace, " ", { pos: 1, line: 0, character: 1 }],
      [Token.Identifier, "x", { pos: 2, line: 0, character: 2 }],
      [Token.NewLine, "\r", { pos: 3, line: 0, character: 3 }],

      [Token.Identifier, "aa", { pos: 4, line: 1, character: 0 }],
      [Token.Whitespace, " ", { pos: 6, line: 1, character: 2 }],
      [Token.Identifier, "x", { pos: 7, line: 1, character: 3 }],
      [Token.NewLine, "\r\n", { pos: 8, line: 1, character: 4 }],

      [Token.Identifier, "aaa", { pos: 10, line: 2, character: 0 }],
      [Token.Whitespace, " ", { pos: 13, line: 2, character: 3 }],
      [Token.Identifier, "x", { pos: 14, line: 2, character: 4 }],
      [Token.NewLine, "\n", { pos: 15, line: 2, character: 5 }],

      [Token.Identifier, "aaaa", { pos: 16, line: 3, character: 0 }],
      [Token.Whitespace, " ", { pos: 20, line: 3, character: 4 }],
      [Token.Identifier, "x", { pos: 21, line: 3, character: 5 }],
      [Token.Whitespace, "\u{2028}", { pos: 22, line: 3, character: 6 }],

      [Token.Identifier, "aaaaa", { pos: 23, line: 3, character: 7 }],
      [Token.Whitespace, " ", { pos: 28, line: 3, character: 12 }],
      [Token.Identifier, "x", { pos: 29, line: 3, character: 13 }],
      [Token.Whitespace, "\u{2029}", { pos: 30, line: 3, character: 14 }],

      [Token.Identifier, "aaaaaa", { pos: 31, line: 3, character: 15 }],
      [Token.Whitespace, " ", { pos: 37, line: 3, character: 21 }],
      [Token.Identifier, "x", { pos: 38, line: 3, character: 22 }],
    ]);
  });

  it("scans backticked identifiers", () => {
    const all = tokens(
      "`a` `01-01`\n`aa x`\r\n`1+1=2` `1!=2` `x\\`x` `\\\\x`\u{2028}`3.14`\u{2029}`import` `a\\n\\t\\`b`"
    );
    verify(all, [
      [Token.Identifier, "`a`", { pos: 0, value: "a", line: 0, character: 0 }],
      [Token.Whitespace, " ", { pos: 3, value: " ", line: 0, character: 3 }],
      [Token.Identifier, "`01-01`", { pos: 4, value: "01-01", line: 0, character: 4 }],
      [Token.NewLine, "\n", { pos: 11, value: "\n", line: 0, character: 11 }],

      [Token.Identifier, "`aa x`", { pos: 12, value: "aa x", line: 1, character: 0 }],
      [Token.NewLine, "\r\n", { pos: 18, value: "\r\n", line: 1, character: 6 }],
      [Token.Identifier, "`1+1=2`", { pos: 20, value: "1+1=2", line: 2, character: 0 }],
      [Token.Whitespace, " ", { pos: 27, value: " ", line: 2, character: 7 }],

      [Token.Identifier, "`1!=2`", { pos: 28, value: "1!=2", line: 2, character: 8 }],
      [Token.Whitespace, " ", { pos: 34, value: " ", line: 2, character: 14 }],
      [Token.Identifier, "`x\\`x`", { pos: 35, value: "x`x", line: 2, character: 15 }],
      [Token.Whitespace, " ", { pos: 41, value: " ", line: 2, character: 21 }],

      [Token.Identifier, "`\\\\x`", { pos: 42, value: "\\x", line: 2, character: 22 }],
      [Token.Whitespace, "\u{2028}", { pos: 47, value: "\u{2028}", line: 2, character: 27 }],
      [Token.Identifier, "`3.14`", { pos: 48, value: "3.14", line: 2, character: 28 }],
      [Token.Whitespace, "\u{2029}", { pos: 54, value: "\u{2029}", line: 2, character: 34 }],

      [Token.Identifier, "`import`", { pos: 55, value: "import", line: 2, character: 35 }],
      [Token.Whitespace, " ", { pos: 63, value: " ", line: 2, character: 43 }],
      [Token.Identifier, "`a\\n\\t\\`b`", { pos: 64, value: "a\n\t`b", line: 2, character: 44 }],
    ]);
  });

  it("normalizes non-ASCII characters in backticked identifiers", () => {
    const all = tokens("`\u{d83d}\u{de0d}` `\u{00f1} is \u{006e}\u{0303}` \u{00f1}");
    verify(all, [
      [
        Token.Identifier,
        "`\u{d83d}\u{de0d}`",
        { pos: 0, value: "\u{d83d}\u{de0d}", line: 0, character: 0 },
      ],
      [Token.Whitespace, " ", { pos: 4, value: " ", line: 0, character: 4 }],
      [Token.Identifier, "`ñ is ñ`", { pos: 5, value: "ñ is ñ", line: 0, character: 5 }],
      [Token.Whitespace, " ", { pos: 14, value: " ", line: 0, character: 14 }],
      [Token.Identifier, "ñ", { pos: 15, value: "ñ", line: 0, character: 15 }],
    ]);
  });

  // https://github.com/microsoft/typespec/issues/168
  it("scan file ending with multi-line comment", () => {
    const multiLineComment = "/* foo\n*bar\n*/";
    verify(tokens(multiLineComment), [
      [Token.MultiLineComment, multiLineComment, { pos: 0, line: 0, character: 0 }],
    ]);
    verify(tokens(`namespace Bar;\n${multiLineComment}`), [
      [Token.NamespaceKeyword, "namespace", { pos: 0, line: 0, character: 0 }],
      [Token.Whitespace, " ", { pos: 9, line: 0, character: 9 }],
      [Token.Identifier, "Bar", { pos: 10, line: 0, character: 10 }],
      [Token.Semicolon, ";", { pos: 13, line: 0, character: 13 }],
      [Token.NewLine, "\n", { pos: 14, line: 0, character: 14 }],
      [Token.MultiLineComment, multiLineComment, { pos: 15, line: 1, character: 0 }],
    ]);
  });

  // It's easy to forget to update TokenDisplay or Min/Max ranges...
  it("provides friendly token display and classification", () => {
    // check that keywords have appropriate display and limits
    const nonStatementKeywords = [
      Token.ExtendsKeyword,
      Token.ReturnKeyword,
      Token.TrueKeyword,
      Token.FalseKeyword,
      Token.VoidKeyword,
      Token.NeverKeyword,
      Token.UnknownKeyword,
      Token.ExternKeyword,
    ];
    let minKeywordLengthFound = Number.MAX_SAFE_INTEGER;
    let maxKeywordLengthFound = Number.MIN_SAFE_INTEGER;

    for (const [name, token] of Keywords) {
      assert.match(
        name,
        /^[a-z]+$/,
        "We need to change the keyword lookup algorithm in the scanner if we ever add a keyword that is not all lowercase ascii letters."
      );
      minKeywordLengthFound = Math.min(minKeywordLengthFound, name.length);
      maxKeywordLengthFound = Math.max(maxKeywordLengthFound, name.length);

      assert.strictEqual(TokenDisplay[token], `'${name}'`, "token display should match");
      assert(isKeyword(token), `${name} should be classified as a keyword`);
      if (nonStatementKeywords.includes(token)) {
        assert(
          !isStatementKeyword(token),
          `${name} should not be classified as a statement keyword`
        );
      } else {
        assert(isStatementKeyword(token), `${name} should be classified as statement keyword`);
      }
    }

    assert.strictEqual(
      minKeywordLengthFound,
      KeywordLimit.MinLength,
      `min keyword length is incorrect, set KeywordLimit.MinLength to ${minKeywordLengthFound}`
    );

    assert.strictEqual(
      maxKeywordLengthFound,
      KeywordLimit.MaxLength,
      `max keyword length is incorrect, set KeywordLimit.MaxLength to ${maxKeywordLengthFound}`
    );

    // check single character punctuation
    for (let i = 33; i <= 126; i++) {
      const str = String.fromCharCode(i);
      const token = createScanner(str, () => ({})).scan();
      if (
        token !== Token.StringLiteral &&
        token !== Token.Identifier &&
        token !== Token.Invalid &&
        token !== Token.NumericLiteral
      ) {
        assert.strictEqual(TokenDisplay[token], `'${str}'`);
        assert(isPunctuation(token), `'${str}' should be classified as punctuation`);
      }
    }

    // check the rest
    assert.strictEqual(TokenDisplay[Token.Ellipsis], "'...'");
    assert.strictEqual(TokenDisplay[Token.None], "none");
    assert.strictEqual(TokenDisplay[Token.Invalid], "invalid");
    assert.strictEqual(TokenDisplay[Token.EndOfFile], "end of file");
    assert.strictEqual(TokenDisplay[Token.SingleLineComment], "single-line comment");
    assert.strictEqual(TokenDisplay[Token.MultiLineComment], "multi-line comment");
    assert.strictEqual(TokenDisplay[Token.NewLine], "newline");
    assert.strictEqual(TokenDisplay[Token.Whitespace], "whitespace");
    assert.strictEqual(TokenDisplay[Token.ConflictMarker], "conflict marker");
    assert.strictEqual(TokenDisplay[Token.Identifier], "identifier");
  });

  // Search for Other_ID_Start in https://www.unicode.org/Public/UCD/latest/ucd/PropList.txt
  const otherIDStart = [0x1885, 0x1886, 0x2118, 0x212e, 0x309b, 0x309c];

  // Search for Other_ID_Continue in https://www.unicode.org/Public/UCD/latest/ucd/PropList.txt
  const otherIdContinue = [
    0x00b7, 0x0387, 0x1369, 0x136a, 0x136b, 0x136c, 0x136d, 0x136e, 0x136f, 0x1370, 0x1371, 0x19da,
  ];

  it("allows additional identifier start characters", () => {
    assert(isIdentifierStart("$".codePointAt(0)!), "'$' should be allowed to start identifier.");
    assert(isIdentifierStart("_".codePointAt(0)!), "'_' should be allowed to start identifier.");

    for (const codePoint of otherIDStart) {
      assert(
        isIdentifierStart(codePoint),
        `U+${codePoint.toString(16)} should be allowed to start identifier.`
      );
    }
  });

  it("allows additional identifier continuation characters", () => {
    //prettier-ignore
    assert(isIdentifierContinue("$".codePointAt(0)!), "'$' should be allowed to continue identifier.");
    //prettier-ignore
    assert(isIdentifierContinue("_".codePointAt(0)!), "'_' should be allowed to continue identifier.");

    for (const codePoint of [...otherIDStart, ...otherIdContinue]) {
      assert(
        isIdentifierContinue(codePoint),
        `U+${codePoint.toString(16)} should be allowed to continue identifier.`
      );
    }
    // cspell:disable-next-line
    assert(isIdentifierContinue(0x200c), "U+200C (ZWNJ) should be allowed to continue identifier.");
    assert(isIdentifierContinue(0x200d), "U+200D (ZWJ) should be allowed to continue identifier.");
  });

  describe("keyword collision", () => {
    // cspell:disable-next-line
    for (const identifier of ["outerface", "famespace", "notanamespace", "notaninterface"]) {
      it(`does not think ${identifier} is a keyword`, () => {
        const [[token]] = tokens(identifier);
        assert.strictEqual(token, Token.Identifier);
      });
    }
  });

  it("scans this file", async () => {
    const text = await readFile(new URL(import.meta.url), "utf-8");
    tokens(text, function () {
      /* ignore errors */
    });
  });
});
