#include <Io.h>

#include <Memory.h>

#include <errno.h>
#include <stdio.h>

#ifndef IO_PRINTF_BUFFER
#define IO_PRINTF_BUFFER 1024
#endif

struct Io
{
    IoFunctions io;
    void *cookie;
};

Io *
IoCreate(void *cookie, IoFunctions funcs)
{
    Io *io;

    /* Must have at least read or write */
    if (!funcs.read && !funcs.write)
    {
        return NULL;
    }

    io = Malloc(sizeof(Io));

    if (!io)
    {
        return NULL;
    }

    io->cookie = cookie;

    io->io.read = funcs.read;
    io->io.write = funcs.write;
    io->io.seek = funcs.seek;
    io->io.close = funcs.close;

    return io;
}

ssize_t
IoRead(Io *io, void *buf, size_t nBytes)
{
    if (!io || !io->io.read)
    {
        errno = EBADF;
        return -1;
    }

    return io->io.read(io->cookie, buf, nBytes);
}

ssize_t
IoWrite(Io *io, void *buf, size_t nBytes)
{
    if (!io || !io->io.write)
    {
        errno = EBADF;
        return -1;
    }

    return io->io.write(io->cookie, buf, nBytes);
}

off_t
IoSeek(Io *io, off_t offset, int whence)
{
    if (!io)
    {
        errno = EBADF;
        return -1;
    }

    if (!io->io.seek)
    {
        errno = EINVAL;
        return -1;
    }

    return io->io.seek(io->cookie, offset, whence);
}

int
IoClose(Io *io)
{
    int ret;

    if (!io)
    {
        errno = EBADF;
        return -1;
    }

    if (io->io.close)
    {
        ret = io->io.close(io->cookie);
    }
    else
    {
        ret = 0;
    }

    Free(io);

    return ret;
}

static ssize_t
IoReadFd(void *cookie, void *buf, size_t nBytes)
{
    int fd = *((int *) cookie);

    return read(fd, buf, nBytes);
}

static ssize_t
IoWriteFd(void *cookie, void *buf, size_t nBytes)
{
    int fd = *((int *) cookie);

    return write(fd, buf, nBytes);
}

static off_t
IoSeekFd(void *cookie, off_t offset, int whence)
{
    int fd = *((int *) cookie);

    return lseek(fd, offset, whence);
}

static int
IoCloseFd(void *cookie)
{
    int fd = *((int *) cookie);

    Free(cookie);
    return close(fd);
}

Io *
IoOpen(int fd)
{
    int *cookie = Malloc(sizeof(int));
    IoFunctions f;

    if (!cookie)
    {
        return NULL;
    }

    *cookie = fd;

    f.read = IoReadFd;
    f.write = IoWriteFd;
    f.seek = IoSeekFd;
    f.close = IoCloseFd;

    return IoCreate(cookie, f);
}

int
IoVprintf(Io *io, const char *fmt, va_list ap)
{
    char *buf;
    size_t write;

    int ret;

    if (!io || !fmt)
    {
        return -1;
    }

    buf = Malloc(IO_PRINTF_BUFFER);
    if (!buf)
    {
        return -1;
    }

    write = vsnprintf(buf, IO_PRINTF_BUFFER, fmt, ap);

    if (write < 0)
    {
        Free(buf);
        return write;
    }

    /* Number of bytes to write exceeded buffer size; this should
     * be rare, but may occasionally happen. If it does, realloc to
     * the correct size and try again.
     */
    if (write >= IO_PRINTF_BUFFER)
    {
        char *new = Realloc(buf, write + 1);
        if (!new)
        {
            Free(buf);
            return -1;
        }

        buf = new;

        /* This time we don't care about the return value */
        vsnprintf(buf, write, fmt, ap);
    }

    ret = IoWrite(io, buf, write);

    Free(buf);
    return ret;
}

int
IoPrintf(Io *io, const char *fmt, ...)
{
    va_list ap;
    int ret;

    va_start(ap, fmt);
    ret = IoVprintf(io, fmt, ap);
    va_end(ap);

    return ret;
}