#include <xrpl/beast/core/LexicalCast.h>
#include <xrpl/beast/unit_test/suite.h>
#include <xrpl/beast/xor_shift_engine.h>

#include <cstdint>
#include <limits>
#include <sstream>
#include <string>

namespace beast {

class LexicalCast_test : public unit_test::suite
{
public:
    template <class IntType>
    static IntType
    nextRandomInt(xor_shift_engine& r)
    {
        return static_cast<IntType>(r());
    }

    template <class IntType>
    void
    testInteger(IntType in)
    {
        std::string s;
        IntType out = static_cast<IntType>(~in);  // Ensure out != in

        expect(lexicalCastChecked(s, in));
        expect(lexicalCastChecked(out, s));
        expect(out == in);
    }

    template <class IntType>
    void
    testIntegers(xor_shift_engine& r)
    {
        {
            std::stringstream ss;
            ss << "random " << typeid(IntType).name();
            testcase(ss.str());

            for (int i = 0; i < 1000; ++i)
            {
                IntType const value(nextRandomInt<IntType>(r));
                testInteger(value);
            }
        }

        {
            std::stringstream ss;
            ss << "numeric_limits <" << typeid(IntType).name() << ">";
            testcase(ss.str());

            testInteger(std::numeric_limits<IntType>::min());
            testInteger(std::numeric_limits<IntType>::max());
        }
    }

    void
    testPathologies()
    {
        testcase("pathologies");
        try
        {
            lexicalCastThrow<int>("\xef\xbc\x91\xef\xbc\x90");  // utf-8 encoded
        }
        catch (BadLexicalCast const&)
        {
            pass();
        }
    }

    template <class T>
    void
    tryBadConvert(std::string const& s)
    {
        T out;
        expect(!lexicalCastChecked(out, s), s);
    }

    void
    testConversionOverflows()
    {
        testcase("conversion overflows");

        tryBadConvert<std::uint64_t>("99999999999999999999");
        tryBadConvert<std::uint32_t>("4294967300");
        tryBadConvert<std::uint16_t>("75821");
    }

    void
    testConversionUnderflows()
    {
        testcase("conversion underflows");

        tryBadConvert<std::uint32_t>("-1");

        tryBadConvert<std::int64_t>("-99999999999999999999");
        tryBadConvert<std::int32_t>("-4294967300");
        tryBadConvert<std::int16_t>("-75821");
    }

    template <class T>
    bool
    tryEdgeCase(std::string const& s)
    {
        T ret;

        bool const result = lexicalCastChecked(ret, s);

        if (!result)
            return false;

        return s == std::to_string(ret);
    }

    void
    testEdgeCases()
    {
        testcase("conversion edge cases");

        expect(tryEdgeCase<std::uint64_t>("18446744073709551614"));
        expect(tryEdgeCase<std::uint64_t>("18446744073709551615"));
        expect(!tryEdgeCase<std::uint64_t>("18446744073709551616"));

        expect(tryEdgeCase<std::int64_t>("9223372036854775806"));
        expect(tryEdgeCase<std::int64_t>("9223372036854775807"));
        expect(!tryEdgeCase<std::int64_t>("9223372036854775808"));

        expect(tryEdgeCase<std::int64_t>("-9223372036854775807"));
        expect(tryEdgeCase<std::int64_t>("-9223372036854775808"));
        expect(!tryEdgeCase<std::int64_t>("-9223372036854775809"));

        expect(tryEdgeCase<std::uint32_t>("4294967294"));
        expect(tryEdgeCase<std::uint32_t>("4294967295"));
        expect(!tryEdgeCase<std::uint32_t>("4294967296"));

        expect(tryEdgeCase<std::int32_t>("2147483646"));
        expect(tryEdgeCase<std::int32_t>("2147483647"));
        expect(!tryEdgeCase<std::int32_t>("2147483648"));

        expect(tryEdgeCase<std::int32_t>("-2147483647"));
        expect(tryEdgeCase<std::int32_t>("-2147483648"));
        expect(!tryEdgeCase<std::int32_t>("-2147483649"));

        expect(tryEdgeCase<std::uint16_t>("65534"));
        expect(tryEdgeCase<std::uint16_t>("65535"));
        expect(!tryEdgeCase<std::uint16_t>("65536"));

        expect(tryEdgeCase<std::int16_t>("32766"));
        expect(tryEdgeCase<std::int16_t>("32767"));
        expect(!tryEdgeCase<std::int16_t>("32768"));

        expect(tryEdgeCase<std::int16_t>("-32767"));
        expect(tryEdgeCase<std::int16_t>("-32768"));
        expect(!tryEdgeCase<std::int16_t>("-32769"));
    }

    template <class T>
    void
    testThrowConvert(std::string const& s, bool success)
    {
        bool result = !success;
        T out;

        try
        {
            out = lexicalCastThrow<T>(s);
            result = true;
        }
        catch (BadLexicalCast const&)
        {
            result = false;
        }

        expect(result == success, s);
    }

    void
    testThrowingConversions()
    {
        testcase("throwing conversion");

        testThrowConvert<std::uint64_t>("99999999999999999999", false);
        testThrowConvert<std::uint64_t>("9223372036854775806", true);

        testThrowConvert<std::uint32_t>("4294967290", true);
        testThrowConvert<std::uint32_t>("42949672900", false);
        testThrowConvert<std::uint32_t>("429496729000", false);
        testThrowConvert<std::uint32_t>("4294967290000", false);

        testThrowConvert<std::int32_t>("5294967295", false);
        testThrowConvert<std::int32_t>("-2147483644", true);

        testThrowConvert<std::int16_t>("66666", false);
        testThrowConvert<std::int16_t>("-5711", true);
    }

    void
    testZero()
    {
        testcase("zero conversion");

        {
            std::int32_t out = 0;

            expect(lexicalCastChecked(out, "-0"), "0");
            expect(lexicalCastChecked(out, "0"), "0");
            expect(lexicalCastChecked(out, "+0"), "0");
        }

        {
            std::uint32_t out = 0;

            expect(!lexicalCastChecked(out, "-0"), "0");
            expect(lexicalCastChecked(out, "0"), "0");
            expect(lexicalCastChecked(out, "+0"), "0");
        }
    }

    void
    testEntireRange()
    {
        testcase("entire range");

        std::int32_t i = std::numeric_limits<std::int16_t>::min();
        std::string const empty;

        while (i <= std::numeric_limits<std::int16_t>::max())
        {
            std::int16_t const j = static_cast<std::int16_t>(i);

            auto actual = std::to_string(j);

            auto result = lexicalCast(j, empty);

            expect(result == actual, actual + " (string to integer)");

            if (result == actual)
            {
                auto number = lexicalCast<std::int16_t>(result);

                if (number != j)
                    expect(false, actual + " (integer to string)");
            }

            i++;
        }
    }

    void
    run() override
    {
        std::int64_t const seedValue = 50;

        xor_shift_engine r(seedValue);

        testIntegers<int>(r);
        testIntegers<unsigned int>(r);
        testIntegers<short>(r);
        testIntegers<unsigned short>(r);
        testIntegers<std::int32_t>(r);
        testIntegers<std::uint32_t>(r);
        testIntegers<std::int64_t>(r);
        testIntegers<std::uint64_t>(r);

        testPathologies();
        testConversionOverflows();
        testConversionUnderflows();
        testThrowingConversions();
        testZero();
        testEdgeCases();
        testEntireRange();
    }
};

BEAST_DEFINE_TESTSUITE(LexicalCast, beast, beast);

}  // namespace beast