#include "rpc_streams.h"

static bool stream_read(pb_istream_t *stream, uint8_t *buf, size_t count)
{
    rpc_istream_t *state = (rpc_istream_t*)stream->state;
    
    if (buf == NULL)
    {
        uint8_t dummy;
        while (count--)
        {
            if (fread(&dummy, 1, 1, state->file) != 1)
                return false;
            state->checksum ^= dummy;
        }
    }
    else
    {
        if (fread(buf, 1, count, state->file) != count)
            return false;
        for (size_t i = 0; i < count; i++)
            state->checksum ^= buf[i];
    }
    
    return true;
}

bool rpc_istream_start(rpc_istream_t *stream)
{
    uint8_t hdr[3];
    if (fread(hdr, 1, 3, stream->file) != 3)
        return false;
    
    stream->stream.callback = &stream_read;
    stream->stream.state = &stream;
    stream->stream.bytes_left = (hdr[0] << 8) | hdr[1];
    stream->msgtype = hdr[2];
    stream->checksum = 0xFF ^ hdr[2];
    
    return true;
}

bool rpc_istream_end(rpc_istream_t *stream)
{
    if (stream->stream.bytes_left != 0)
    {
        if (!pb_read(&stream->stream, NULL, stream->stream.bytes_left))
            return false;
    }
    
    uint8_t checksum;
    if (!fread(&checksum, 1, 1, stream->file))
        return false;
    
    if (checksum != stream->checksum)
        return false;
    
    return true;
}

static bool stream_write(pb_ostream_t *stream, const uint8_t *buf, size_t count)
{
    rpc_istream_t *state = (rpc_istream_t*)stream->state;
    
    for (size_t i = 0; i < count; i++)
        state->checksum ^= buf[i];
    
    return fwrite(buf, 1, count, state->file) == count;
}

bool rpc_ostream_start(rpc_ostream_t *stream, RPCCommand msgtype, size_t length)
{
    if (length > 65535)
        return false;
    
    uint8_t hdr[3] = {length >> 8, length & 0xFF, msgtype};
    if (fwrite(hdr, 1, 3, stream->file) != 3)
        return false;
    
    stream->stream.callback = &stream_write;
    stream->stream.state = &stream;
    stream->stream.bytes_written = 0;
    stream->stream.max_size = length - 2;
    stream->checksum = 0xFF ^ msgtype;
    
    return true;
}

bool rpc_ostream_end(rpc_ostream_t *stream)
{
    if (stream->stream.bytes_written != stream->stream.max_size)
        return false;
    
    return fwrite(&stream->checksum, 1, 1, stream->file);
}