// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#include "toolchain/lex/numeric_literal.h"

#include <gmock/gmock.h>
#include <gtest/gtest.h>

#include <optional>
#include <string>

#include "common/check.h"
#include "toolchain/diagnostics/diagnostic_emitter.h"
#include "toolchain/lex/test_helpers.h"

namespace Carbon::Lex {
namespace {

using ::testing::_;
using ::testing::Field;
using ::testing::Matcher;
using ::testing::Property;
using ::testing::Truly;
using ::testing::VariantWith;

class NumericLiteralTest : public ::testing::Test {
 public:
  NumericLiteralTest() : error_tracker(Diagnostics::ConsoleConsumer()) {}

  auto Lex(llvm::StringRef text, bool can_form_real_literal) -> NumericLiteral {
    std::optional<NumericLiteral> result =
        NumericLiteral::Lex(text, can_form_real_literal);
    CARBON_CHECK(result);
    if (can_form_real_literal) {
      EXPECT_EQ(result->text(), text);
    }
    return *result;
  }

  auto Parse(llvm::StringRef text, bool can_form_real_literal = true)
      -> NumericLiteral::Value {
    Testing::SingleTokenDiagnosticEmitter emitter(&error_tracker, text);
    return Lex(text, can_form_real_literal).ComputeValue(emitter);
  }

  Diagnostics::ErrorTrackingConsumer error_tracker;
};

// Matcher for signed llvm::APInt.
auto IsSignedInt(int64_t value) -> Matcher<llvm::APInt> {
  return Property(&llvm::APInt::getSExtValue, value);
}

// Matcher for unsigned llvm::APInt.
auto IsUnsignedInt(uint64_t value) -> Matcher<llvm::APInt> {
  return Property(&llvm::APInt::getZExtValue, value);
}

// Matcher for an integer literal value.
template <typename ValueMatcher>
auto HasIntValue(const ValueMatcher& value_matcher)
    -> Matcher<NumericLiteral::Value> {
  return VariantWith<NumericLiteral::IntValue>(
      Field(&NumericLiteral::IntValue::value, value_matcher));
}

struct RealMatcher {
  Matcher<int> radix = _;
  Matcher<llvm::APInt> mantissa = _;
  Matcher<llvm::APInt> exponent = _;
};

// Matcher for a real literal value.
auto HasRealValue(const RealMatcher& real_matcher)
    -> Matcher<NumericLiteral::Value> {
  return VariantWith<NumericLiteral::RealValue>(AllOf(
      Field(&NumericLiteral::RealValue::radix, real_matcher.radix),
      Field(&NumericLiteral::RealValue::mantissa, real_matcher.mantissa),
      Field(&NumericLiteral::RealValue::exponent, real_matcher.exponent)));
}

// Matcher for an unrecoverable parse error.
auto HasUnrecoverableError() -> Matcher<NumericLiteral::Value> {
  return VariantWith<NumericLiteral::UnrecoverableError>(_);
}

TEST_F(NumericLiteralTest, HandlesIntLiteral) {
  struct Testcase {
    llvm::StringLiteral token;
    uint64_t value;
    int radix;
  };
  Testcase testcases[] = {
      {.token = "12", .value = 12, .radix = 10},
      {.token = "0x12_3ABC", .value = 0x12'3ABC, .radix = 16},
      {.token = "0b10_10_11", .value = 0b10'10'11, .radix = 2},
      {.token = "1_234_567", .value = 1'234'567, .radix = 10},
  };
  for (bool can_form_real_literal : {false, true}) {
    for (Testcase testcase : testcases) {
      error_tracker.Reset();
      EXPECT_THAT(Parse(testcase.token, can_form_real_literal),
                  HasIntValue(IsUnsignedInt(testcase.value)))
          << testcase.token;
      EXPECT_FALSE(error_tracker.seen_error()) << testcase.token;
    }
  }
}

TEST_F(NumericLiteralTest, ValidatesBaseSpecifier) {
  llvm::StringLiteral valid[] = {
      // Decimal integer literals.
      "0",
      "1",
      "123456789000000000000000000000000000000000000",

      // Hexadecimal integer literals.
      "0x0123456789ABCDEF",
      "0x0000000000000000000000000000000",

      // Binary integer literals.
      "0b10110100101001010",
      "0b0000000",
  };
  for (llvm::StringLiteral literal : valid) {
    error_tracker.Reset();
    EXPECT_THAT(Parse(literal), HasIntValue(_)) << literal;
    EXPECT_FALSE(error_tracker.seen_error()) << literal;
  }

  llvm::StringLiteral invalid[] = {
      "00",  "0X123",    "0o123",          "0B1",
      "007", "123L",     "123456789A",     "0x",
      "0b",  "0x123abc", "0b011101201001", "0b10A",
      "0x_", "0b_",
  };
  for (llvm::StringLiteral literal : invalid) {
    error_tracker.Reset();
    EXPECT_THAT(Parse(literal), HasUnrecoverableError()) << literal;
    EXPECT_TRUE(error_tracker.seen_error()) << literal;
  }
}

TEST_F(NumericLiteralTest, ValidatesIntDigitSeparators) {
  llvm::StringLiteral valid[] = {
      // Decimal literals.
      "1_234",
      "123_456",
      "1_234_567",
      "12_34",
      "123_4_6_789",
      "12_3456_789",

      // Hexadecimal literals.
      "0x1_0000",
      "0x1000_0000",
      "0x1_0000_0000",
      "0x12_3",
      "0x1234_567",

      // Binary literals.
      "0b1_0_1_0_1_0",
      "0b111_0000",
  };
  for (llvm::StringLiteral literal : valid) {
    error_tracker.Reset();
    EXPECT_THAT(Parse(literal), HasIntValue(_)) << literal;
    EXPECT_FALSE(error_tracker.seen_error()) << literal;
  }

  llvm::StringLiteral invalid[] = {
      // Decimal literals.
      "12__345",
      "1_",

      // Hexadecimal literals.
      "0x_1234",
      "0x123_",
      "0x_234_5678",

      // Binary literals.
      "0b_10101",
      "0b1__01",
      "0b1011_",
      "0b1_01_01_",
  };
  for (llvm::StringLiteral literal : invalid) {
    error_tracker.Reset();
    EXPECT_THAT(Parse(literal), HasIntValue(_)) << literal;
    EXPECT_TRUE(error_tracker.seen_error()) << literal;
  }
}

TEST_F(NumericLiteralTest, HandlesRealLiteral) {
  struct Testcase {
    llvm::StringLiteral token;
    uint64_t mantissa;
    int64_t exponent;
    unsigned radix;
    uint64_t int_value;
  };
  Testcase testcases[] = {
      // Decimal real literals.
      {.token = "0.0",
       .mantissa = 0,
       .exponent = -1,
       .radix = 10,
       .int_value = 0},
      {.token = "12.345",
       .mantissa = 12345,
       .exponent = -3,
       .radix = 10,
       .int_value = 12},
      {.token = "12.345e6",
       .mantissa = 12345,
       .exponent = 3,
       .radix = 10,
       .int_value = 12},
      {.token = "12.345e+6",
       .mantissa = 12345,
       .exponent = 3,
       .radix = 10,
       .int_value = 12},
      {.token = "1_234.5e-2",
       .mantissa = 12345,
       .exponent = -3,
       .radix = 10,
       .int_value = 1234},
      {.token = "1.0e-2_000_000",
       .mantissa = 10,
       .exponent = -2'000'001,
       .radix = 10,
       .int_value = 1},

      // Hexadecimal real literals.
      {.token = "0x1_2345_6789.CDEF",
       .mantissa = 0x1'2345'6789'CDEF,
       .exponent = -16,
       .radix = 16,
       .int_value = 0x1'2345'6789},
      {.token = "0x0.0001p4",
       .mantissa = 1,
       .exponent = -12,
       .radix = 16,
       .int_value = 0},
      {.token = "0x0.0001p+4",
       .mantissa = 1,
       .exponent = -12,
       .radix = 16,
       .int_value = 0},
      {.token = "0x0.0001p-4",
       .mantissa = 1,
       .exponent = -20,
       .radix = 16,
       .int_value = 0},
      // The exponent here works out as exactly INT64_MIN.
      {.token = "0x1.01p-9223372036854775800",
       .mantissa = 0x101,
       .exponent = -9223372036854775807L - 1L,
       .radix = 16,
       .int_value = 1},
      // The exponent here doesn't fit in a signed 64-bit integer until we
      // adjust for the radix point.
      {.token = "0x1.01p9223372036854775809",
       .mantissa = 0x101,
       .exponent = 9223372036854775801L,
       .radix = 16,
       .int_value = 1},

      // Binary real literals. These are invalid, but we accept them for error
      // recovery.
      {.token = "0b10_11_01.01",
       .mantissa = 0b10110101,
       .exponent = -2,
       .radix = 2,
       .int_value = 0b101101},
  };
  // Check we get the right real value.
  for (Testcase testcase : testcases) {
    error_tracker.Reset();
    EXPECT_THAT(Parse(testcase.token),
                HasRealValue({.radix = (testcase.radix == 10 ? 10 : 2),
                              .mantissa = IsUnsignedInt(testcase.mantissa),
                              .exponent = IsSignedInt(testcase.exponent)}))
        << testcase.token;
    EXPECT_EQ(error_tracker.seen_error(), testcase.radix == 2)
        << testcase.token;
  }
  // If we are required to stop at the `.` character, check we get the right int
  // value instead.
  for (Testcase testcase : testcases) {
    error_tracker.Reset();
    EXPECT_THAT(Parse(testcase.token, false),
                HasIntValue(IsUnsignedInt(testcase.int_value)))
        << testcase.token;
    EXPECT_FALSE(error_tracker.seen_error());
  }
}

TEST_F(NumericLiteralTest, HandlesRealLiteralOverflow) {
  llvm::StringLiteral input = "0x1.000001p-9223372036854775800";
  error_tracker.Reset();
  EXPECT_THAT(
      Parse(input),
      HasRealValue({.radix = 2,
                    .mantissa = IsUnsignedInt(0x1000001),
                    .exponent = Truly([](llvm::APInt exponent) {
                      return (exponent + 9223372036854775800).getSExtValue() ==
                             -24;
                    })}));
  EXPECT_FALSE(error_tracker.seen_error());
}

TEST_F(NumericLiteralTest, ValidatesRealLiterals) {
  llvm::StringLiteral invalid[] = {
      // No digits in integer part.
      "0x.0",
      "0b.0",
      "0x_.0",
      "0b_.0",

      // No digits in fractional part.
      "0.e",
      "0.e0",
      "0.e+0",
      "0x0.p",
      "0x0.p-0",

      // Invalid digits in mantissa.
      "123A.4",
      "123.4A",
      "123A.4e0",
      "123.4Ae0",
      "0x123ABCDEFG.0",
      "0x123.ABCDEFG",
      "0x123ABCDEFG.0p0",
      "0x123.ABCDEFGp0",

      // Invalid exponent letter.
      "0.0f0",
      "0.0p0",
      "0.0z+0",
      "0x0.0e0",
      "0x0.0f0",
      "0x0.0z-0",

      // No digits in exponent part.
      "0.0e",
      "0x0.0p",
      "0.0e_",
      "0x0.0p_",

      // Invalid digits in exponent part.
      "0.0eHELLO",
      "0.0eA",
      "0.0e+A",
      "0x0.0pA",
      "0x0.0p-A",
  };
  for (llvm::StringLiteral literal : invalid) {
    error_tracker.Reset();
    EXPECT_THAT(Parse(literal), HasUnrecoverableError()) << literal;
    EXPECT_TRUE(error_tracker.seen_error()) << literal;
  }
}

TEST_F(NumericLiteralTest, TooManyDigits) {
  std::string long_number(2000, '1');
  EXPECT_THAT(Parse(long_number), HasUnrecoverableError());
  EXPECT_TRUE(error_tracker.seen_error());
}

}  // namespace
}  // namespace Carbon::Lex
