#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "sys/types.h"
#include "__fio.h"

static struct __io_file __stdin = {};
static struct __io_file __stdout = {};
static struct __io_file __stderr = {};

static int flags_from_mode(const char *r)
{
    return 0;
}

static int refill(struct __io_file *fp)
{
    ssize_t err = read(fp->fd, fp->in_buf, sizeof fp->in_buf);
    if (err < 0) {
        fp->err = 1;
        return 0;
    }

    fp->in_buf_ptr = 0;
    fp->in_buf_len = err;

    return err;
}

FILE *__get_stdio_file(int i)
{
    switch (i) {
    case 0:
        return &__stdin;
    case 1:
        return &__stdout;
    case 2:
        return &__stderr;
    default:
        return NULL;
    }
}

void __fio_init(int in, int out, int err)
{
    __stdin.fd = in;
    __stdout.fd = out;
    __stderr.fd = err;
}

int __fio_fopen(const char *path, const char *mode, struct __io_file *fp)
{
    /* TODO */
    int fd = open(path, 0);
    if (fd == -1) {
        return -1;
    }

    fp->fd = fd;

    return 0;
}

int __fio_fclose(struct __io_file *fp)
{
    if (fp->fd == -1) {
        return -1;
    }

    close(fp->fd);
    fp->fd = -1;
    return 0;
}

int __fio_fdopen(int fd, const char *mode, struct __io_file *fp)
{
    if (fd == -1) {
        return -1;
    }

    fp->fd = fd;

    return 0;
}

int __fileno(struct __io_file *f)
{
    return (int)f->fd;
}

unsigned int __fio_read(struct __io_file *f, char *buf, unsigned int sz)
{
    if (sz == 0) {
        return 0;
    }

    size_t r = 0;
    char *out = buf;

    if (f->unget) {
        *out++ = f->unget;
        f->unget = 0;
        r++;
        sz--;
    }

    size_t available = f->in_buf_len - f->in_buf_ptr;

    size_t bufread = sz;
    if (bufread > available) {
        bufread = available;
    }

    memcpy(out, f->in_buf + f->in_buf_ptr, bufread);
    f->in_buf_ptr += bufread;
    out += bufread;
    sz -= bufread;
    r += bufread;

    if (sz == 0) {
        return r;
    }

    while (1) {
        refill(f);

        available = f->in_buf_len - f->in_buf_ptr;
        if (available == 0) {
            f->eof = 1;
            break;
        }

        bufread = sz;
        if (bufread > available) {
            bufread = available;
        }

        memcpy(out, f->in_buf + f->in_buf_ptr, bufread);
        f->in_buf_ptr += bufread;
        out += bufread;
        sz -= bufread;
        r += bufread;

        if (sz == 0 || f->err || f->eof) {
            break;
        }
    }

    if (sz > 0) {
        f->eof = 1;
    }

    return r;
}

unsigned int __fio_write(struct __io_file *f, const char *buf, unsigned int sz)
{
    for (unsigned int i = 0; i < sz; i++) {
        if (f->out_buf_len >= __FIO_BUFSZ) {
            __fio_flush(f);
        }

        f->out_buf[f->out_buf_len++] = buf[i];
        if (buf[i] == '\n') {
            __fio_flush(f);
        }
    }

    return sz;
}

int __fio_ungetc(struct __io_file *f, char c)
{
    if (f->unget) {
        return -1;
    }

    f->unget = c;
    return 0;
}

unsigned int __fio_flush(struct __io_file *f)
{
    ssize_t res = write(f->fd, f->out_buf, f->out_buf_len);
    if (res != f->out_buf_len) {
        f->err = 1;
    }

    size_t flushed = f->out_buf_len;
    f->out_buf_len = 0;
    return flushed;
}

int __fio_error(struct __io_file *f)
{
    return f->err != 0;
}

int __fio_eof(struct __io_file *f)
{
    return f->eof != 0;
}