#include <stdio.h>

#include <algorithm>
#include <string>
#include <stdarg.h>
#include "os/tools/printf_helper.hpp"
#include "os/tools/ringbuffer.hpp"

#if defined(__baos_kernel_source__)
#include "os/serial.hpp"
#include "os/tty.hpp"
#else
#include "os/syscall.hpp"
#endif

struct __file
{
protected:
    static constexpr unsigned BUFFER_SIZE = 4096;

    baos::RingBuffer<char, BUFFER_SIZE> mBuffer;
    bool mEof = false;
    bool mError = false;
protected:
    virtual bool underflow() noexcept = 0;
public:
    [[nodiscard]] bool isEof() const noexcept { return mEof; }
    [[nodiscard]] bool isError() const noexcept { return mError; }

    bool readChar(char& outChar) noexcept
    {
        while (!mBuffer.next(outChar)) {
            if (!underflow()) {
                return false;
            }
        }
        return true;
    }

    bool readLine(std::string& outLine) noexcept
    {
        outLine.clear();
        while(true)
        {
            while (mBuffer.empty()) {
                if (!underflow()) {
                    return false;
                }
            }
            // first check if there is a \n in the stream
            std::size_t count = mBuffer.size();
            for (std::size_t idx = 0; idx < mBuffer.size(); ++idx)
            {
                if (mBuffer[idx] == '\n')
                {
                    count = idx + 1;
                    break;
                }
            }
            outLine.reserve(outLine.size() + count);
            for (std::size_t idx = 0; idx < count; ++idx)
            {
                char chr = '\0';
                mBuffer.next(chr);
                outLine.append(chr);
            }

            if (outLine.back() == '\n')
            {
                return true;
            }
        }
    }
};

namespace
{
struct RegularPrinter
{
    void putchar(int chr) noexcept // NOLINT
    {
        ::putchar(chr);
    }
};

struct BufferPrinter
{
    char* pos = nullptr;
    char* end = nullptr;

    void putchar(int chr) noexcept // NOLINT
    {
        if (pos != end)
        {
            *pos = static_cast<char>(chr);
            ++pos;
        }
    }
};

class StdinFile : public __file
{
public:
    bool underflow() noexcept override
    {
#if defined(__baos_kernel_source__)
        for (char chr : tty::readLine()) {
            mBuffer.append(chr);
        }
        return true;
#else
        return false; // TODO!!!
#endif
    }
};
StdinFile gStdin;
}

extern "C"
{
FILE* __stdin = &gStdin;

// TODO: line-buffering
int putchar(int chr) noexcept
{
#if defined(__baos_kernel_source__)
    tty::putChar(static_cast<char>(chr));
    if (chr == '\n')
    {
        serialWrite(PORT_COM1, '\r');
        serialWrite(PORT_COM1, '\n');
    }
    else
    {
        serialWrite(PORT_COM1, static_cast<std::uint8_t>(chr));
    }
    return 0;
#else
    char asChar = static_cast<char>(chr);
    baos::doSyscall(baos::Syscall::FILE_WRITE, 0, &asChar, 1);
    return 0;
#endif
}

int puts(const char* str) noexcept
{
#if defined(__baos_kernel_source__)
    while (*str)
    {
        putchar(*str);
        ++str;
    }
    putchar('\n');
    return 0;
#else
    baos::doSyscall(baos::Syscall::FILE_WRITE, 0, str, std::strlen(str));
    return 0;
#endif
}

int printf(const char* format, ...) noexcept
{
    va_list parameters;
    va_start(parameters, format);
    const int result = vprintf(format, parameters);
    va_end(parameters);
    return result;
}

int vprintf(const char* format, va_list vlist) BA_CXX_NOEXCEPT
{
    return baos::PrintFHelper<RegularPrinter>().vprintf(format, vlist);
}

int snprintf(char* buffer, size_t bufferSize, const char* format, ...) noexcept
{
    va_list parameters;
    va_start(parameters, format);
    const int result = vsnprintf(buffer, bufferSize, format, parameters);
    va_end(parameters);
    return result;
}

int vsnprintf(char* buffer, size_t bufferSize, const char* format, va_list vlist) noexcept
{
    BufferPrinter printer{
        .pos = buffer,
        .end = bufferSize > 0 ? buffer + bufferSize - 1 : buffer
    };
    const int length = baos::PrintFHelper(printer).vprintf(format, vlist);
    if (bufferSize > 0)
    {
        buffer[std::min(static_cast<int>(bufferSize - 1), length)] = '\0';
    }
    return length;
}

int fgetc(FILE* stream) noexcept
{
    char chr;
    if (!stream->readChar(chr))
    {
        return EOF;
    }
    return chr;
}

char* fgets(char* buffer, int count, FILE* stream) noexcept
{
    if (count < 1) {
        return nullptr;
    }
    if (count == 1)
    {
        *buffer = '\0';
        return buffer;
    }

    int pos = 0;
    for (; pos < count - 1; ++pos)
    {
        if (!stream->readChar(buffer[pos]))
        {
            if (stream->isError() || pos == 0)
            {
                return nullptr;
            }
            break;
        }
    }
    buffer[pos] = '\0';
    return buffer;
}
} // extern "C"

namespace std
{
bool fgetline(FILE* stream, std::string& outLine) noexcept
{
    return stream->readLine(outLine);
}
}