#include "xfile.h"

#include <assert.h>
#include <stdlib.h>
#include <string.h>

#define min(a,b) (((a)>(b))?(b):(a))
#define max(a,b) (((a)<(b))?(b):(a))

#define XF_EOF 1
#define XF_ERR 2

xFILE *
xfunopen(void *cookie, int (*read)(void *, char *, int), int (*write)(void *, const char *, int), long (*seek)(void *, long, int), int (*flush)(void *), int (*close)(void *))
{
  xFILE *file;

  file = (xFILE *)malloc(sizeof(xFILE));
  if (! file) {
    return NULL;
  }
  file->ungot = -1;
  file->flags = 0;
  /* set vtable */
  file->vtable.cookie = cookie;
  file->vtable.read = read;
  file->vtable.write = write;
  file->vtable.seek = seek;
  file->vtable.flush = flush;
  file->vtable.close = close;

  return file;
}

xFILE *
xfopen(const char *filename, const char *mode)
{
  FILE *fp;
  xFILE *file;

  fp = fopen(filename, mode);
  if (! fp) {
    return NULL;
  }

  file = xfpopen(fp);
  if (! file) {
    return NULL;
  }

  return file;
}

int
xfclose(xFILE *file)
{
  int r;

  r = file->vtable.close(file->vtable.cookie);
  if (r == EOF) {
    return -1;
  }

  free(file);
  return 0;
}

int
xfflush(xFILE *file)
{
  return file->vtable.flush(file->vtable.cookie);
}

size_t
xfread(void *ptr, size_t block, size_t nitems, xFILE *file)
{
  char *dst = (char *)ptr;
  char buf[block];
  size_t i, offset;
  int n;

  for (i = 0; i < nitems; ++i) {
    offset = 0;
    if (file->ungot != -1 && block > 0) {
      buf[0] = file->ungot;
      offset += 1;
      file->ungot = -1;
    }
    while (offset < block) {
      n = file->vtable.read(file->vtable.cookie, buf + offset, block - offset);
      if (n < 0) {
        file->flags |= XF_ERR;
        goto exit;
      }
      if (n == 0) {
        file->flags |= XF_EOF;
        goto exit;
      }
      offset += n;
    }
    memcpy(dst, buf, block);
    dst += block;
  }

 exit:
  return i;
}

size_t
xfwrite(const void *ptr, size_t block, size_t nitems, xFILE *file)
{
  char *dst = (char *)ptr;
  size_t i, offset;
  int n;

  for (i = 0; i < nitems; ++i) {
    offset = 0;
    while (offset < block) {
      n = file->vtable.write(file->vtable.cookie, dst + offset, block - offset);
      if (n < 0) {
        file->flags |= XF_ERR;
        goto exit;
      }
      offset += n;
    }
    dst += block;
  }

 exit:
  return i;
}

long
xfseek(xFILE *file, long offset, int whence)
{
  file->ungot = -1;
  return file->vtable.seek(file->vtable.cookie, offset, whence);
}

long
xftell(xFILE *file)
{
  return xfseek(file, 0, SEEK_CUR);
}

void
xrewind(xFILE *file)
{
  xfseek(file, 0, SEEK_SET);
}

void
xclearerr(xFILE *file)
{
  file->flags = 0;
}

int
xfeof(xFILE *file)
{
  return file->flags & XF_EOF;
}

int
xferror(xFILE *file)
{
  return file->flags & XF_ERR;
}

int
xfgetc(xFILE *file)
{
  char buf[1];

  xfread(buf, 1, 1, file);

  if (xfeof(file)) {
    return EOF;
  }

  return buf[0];
}

int
xungetc(int c, xFILE *file)
{
  file->ungot = c;
  if (c != EOF) {
    file->flags &= ~XF_EOF;
  }
  return c;
}

int
xgetchar(void)
{
  return xfgetc(xstdin);
}

int
xfputc(int c, xFILE *file)
{
  char buf[1];

  buf[0] = c;
  xfwrite(buf, 1, 1, file);

  return buf[0];
}

int
xputchar(int c)
{
  return xfputc(c, xstdout);
}

int
xfputs(const char *str, xFILE *file)
{
  int len;

  len = strlen(str);
  xfwrite(str, len, 1, file);

  return 0;
}

int
xprintf(const char *fmt, ...)
{
  va_list ap;
  int n;

  va_start(ap, fmt);
  n = xvfprintf(xstdout, fmt, ap);
  va_end(ap);
  return n;
}

int
xfprintf(xFILE *stream, const char *fmt, ...)
{
  va_list ap;
  int n;

  va_start(ap, fmt);
  n = xvfprintf(stream, fmt, ap);
  va_end(ap);
  return n;
}

int
xvfprintf(xFILE *stream, const char *fmt, va_list ap)
{
  va_list ap2;

  va_copy(ap2, ap);
  {
    char buf[vsnprintf(NULL, 0, fmt, ap2)];

    vsnprintf(buf, sizeof buf + 1, fmt, ap);

    if (xfwrite(buf, sizeof buf, 1, stream) < 1) {
      return -1;
    }

    va_end(ap2);
    return sizeof buf;
  }
}

/*
 * Derieved xFILE Classes
 */

static FILE *
unpack(void *cookie)
{
  switch ((long)cookie) {
  default: return cookie;
  case 0:  return stdin;
  case 1:  return stdout;
  case -1: return stderr;
  }
}

static int
file_read(void *cookie, char *ptr, int size)
{
  FILE *file = unpack(cookie);
  int r;

  r = fread(ptr, 1, size, file);
  if (r < size && ferror(file)) {
    return -1;
  }
  if (r == 0 && feof(file)) {
    clearerr(file);
  }
  return r;
}

static int
file_write(void *cookie, const char *ptr, int size)
{
  FILE *file = unpack(cookie);
  int r;

  r = fwrite(ptr, 1, size, file);
  if (r < size) {
    return -1;
  }
  return r;
}

static long
file_seek(void *cookie, long pos, int whence)
{
  return fseek(unpack(cookie), pos, whence);
}

static int
file_flush(void *cookie)
{
  return fflush(unpack(cookie));
}

static int
file_close(void *cookie)
{
  return fclose(unpack(cookie));
}

xFILE *
xfpopen(FILE *fp)
{
  xFILE *file;

  file = xfunopen(fp, file_read, file_write, file_seek, file_flush, file_close);
  if (! file) {
    return NULL;
  }

  return file;
}

#define FILE_VTABLE file_read, file_write, file_seek, file_flush, file_close

static xFILE xfile_stdin  = { -1, 0, { (void *)0, FILE_VTABLE } };
static xFILE xfile_stdout = { -1, 0, { (void *)1, FILE_VTABLE } };
static xFILE xfile_stderr = { -1, 0, { (void *)-1, FILE_VTABLE } };

xFILE *xstdin  = &xfile_stdin;
xFILE *xstdout = &xfile_stdout;
xFILE *xstderr = &xfile_stderr;

struct membuf {
  char *buf;
  long pos, end, capa;
};

static int
mem_read(void *cookie, char *ptr, int size)
{
  struct membuf *mem;

  mem = (struct membuf *)cookie;

  size = min(size, mem->end - mem->pos);
  memcpy(ptr, mem->buf + mem->pos, size);
  mem->pos += size;
  return size;
}

static int
mem_write(void *cookie, const char *ptr, int size)
{
  struct membuf *mem;

  mem = (struct membuf *)cookie;

  if (mem->pos + size >= mem->capa) {
    mem->capa = (mem->pos + size) * 2;
    mem->buf = realloc(mem->buf, mem->capa);
  }
  memcpy(mem->buf + mem->pos, ptr, size);
  mem->pos += size;
  mem->end = max(mem->pos, mem->end);
  return size;
}

static long
mem_seek(void *cookie, long pos, int whence)
{
  struct membuf *mem;

  mem = (struct membuf *)cookie;

  switch (whence) {
  case SEEK_SET:
    mem->pos = pos;
    break;
  case SEEK_CUR:
    mem->pos += pos;
    break;
  case SEEK_END:
    mem->pos = mem->end + pos;
    break;
  }

  return mem->pos;
}

static int
mem_flush(void *cookie)
{
  (void)cookie;

  return 0;
}

static int
mem_close(void *cookie)
{
  struct membuf *mem;

  mem = (struct membuf *)cookie;
  free(mem->buf);
  free(mem);
  return 0;
}

xFILE *
xmopen()
{
  struct membuf *mem;

  mem = (struct membuf *)malloc(sizeof(struct membuf));
  mem->buf = (char *)malloc(BUFSIZ);
  mem->pos = 0;
  mem->end = 0;
  mem->capa = BUFSIZ;

  return xfunopen(mem, mem_read, mem_write, mem_seek, mem_flush, mem_close);
}