/**
 * See Copyright Notice in picrin.h
 */

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

#include "picrin.h"
#include "picrin/proc.h"
#include "picrin/port.h"

pic_value
pic_eof_object()
{
  pic_value v;

  pic_init_value(v, PIC_VTYPE_EOF);

  return v;
}

struct pic_port *
pic_stdin(pic_state *pic)
{
  struct pic_proc *proc;

  proc = pic_proc_ptr(pic_ref(pic, "current-input-port"));

  return pic_port_ptr(pic_apply(pic, proc, pic_nil_value()));
}

struct pic_port *
pic_stdout(pic_state *pic)
{
  struct pic_proc *proc;

  proc = pic_proc_ptr(pic_ref(pic, "current-output-port"));

  return pic_port_ptr(pic_apply(pic, proc, pic_nil_value()));
}

int
pic_setvbuf(pic_file *file, char *buf, int mode, size_t bufsiz)
{
  /* FIXME: free old buf */
  assert(mode != _IONBF);       /* FIXME: support IONBF */

  file->mode = mode;
  if (buf) {
    file->buf = buf;
    file->bufsiz = bufsiz;
  }
  else {
    if (mode == _IONBF) {
      file->buf = NULL;
      file->bufsiz = 0;
    }
    else {
      assert(bufsiz == 0);
      file->buf = (char *)malloc(BUFSIZ);
      file->bufsiz = BUFSIZ;
    }
  }
  file->s = file->c = file->buf;
  file->e = file->buf + file->bufsiz;
  return 0;
}

int
pic_fflush(pic_file *file)
{
  int r;

  r = file->vtable.write(file->vtable.cookie, file->s, file->c - file->s);
  /* TODO: error handling (r == -1 or r < file->c - file->s)*/
  file->c -= r;
  return r;
}

int
pic_ffill(pic_file *file)
{
  int r;

  r = file->vtable.read(file->vtable.cookie, file->c, file->e - file->c);
  /* TODO: error handling (r == -1) */
  if (r < file->e - file->c) {
    file->flags |= PIC_FILE_EOF;
  }
  file->c += r;
  return r;
}

pic_file *
pic_funopen(void *cookie,
            int (*read)(void *, char *, int),
            int (*write)(void *, const char *, int),
            long (*seek)(void *, long, int),
            int (*close)(void *))
{
  pic_file *file;

  file = (pic_file *)malloc(sizeof(pic_file));
  if (! file) {
    return NULL;
  }
  file->flags = 0;
  /* no buffering at the beginning */
  file->buf = NULL;
  file->mode = _IONBF;
  file->bufsiz = 0;
  file->us = PIC_UBUFSIZ;
  file->ur = 0;
  /* set vtable */
  file->vtable.cookie = cookie;
  file->vtable.read = read;
  file->vtable.write = write;
  file->vtable.seek = seek;
  file->vtable.close = close;

  pic_setvbuf(file, (char *)NULL, _IOFBF, 0);

  return file;
}

static int
file_read(void *cookie, char *ptr, int size)
{
  return fread(ptr, 1, size, (FILE *)cookie);
}

static int
file_write(void *cookie, const char *ptr, int size)
{
  return fwrite(ptr, 1, size, (FILE *)cookie);
}

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

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

pic_file *
pic_fopen(const char *filename, const char *mode)
{
  FILE *fp;

  fp = fopen(filename, mode);
  if (! fp) {
    return NULL;
  }
  return pic_funopen(fp, file_read, file_write, file_seek, file_close);
}

int
pic_fclose(pic_file *file)
{
  int r;

  r = file->vtable.close(file->vtable.cookie);
  if (! r) {
    return -1;
  }
  free(file);
  return 0;
}

size_t
pic_fread(void *ptr, size_t block, size_t nitems, pic_file *file)
{
  int size, avail;
  char *dst = (char *)ptr;

  size = block * nitems;        /* TODO: optimize block read */

  /* take care of ungetc buf */
  while (file->ur > 0) {
    *dst++ = file->ub[--file->ur];
    if (--size == 0)
      return block * nitems;
  }

  while (1) {
    avail = file->c - file->s;
    if (size <= avail) {
      memcpy(dst, file->s, size);
      memmove(file->s, file->s + size, avail - size);
      file->c -= size;
      return block * nitems;
    }
    else {
      memcpy(dst, file->s, avail);
      file->c = file->s;
      size -= avail;
      dst += avail;
      if ((file->flags & PIC_FILE_EOF) != 0)
        break;
      pic_ffill(file);
    }
  }
  /* handle end-of-file */
  *dst = EOF;
  return block * nitems - size;
}

size_t
pic_fwrite(const void *ptr, size_t block, size_t nitems, pic_file *file)
{
  int size, room;
  char *dst = (char *)ptr;

  size = block * nitems;               /* TODO: optimize block write */
  while (1) {
    room = file->e - file->c;
    if (room < size) {
      memcpy(file->c, dst, room);
      file->c = file->e;
      size -= room;
      dst += room;
      pic_fflush(file);
    }
    else {
      memcpy(file->c, dst, size);
      file->c += size;
      return block * nitems;
    }
  }
}

int
pic_fgetc(pic_file *file)
{
  char buf[1];

  pic_fread(buf, 1, 1, file);

  return buf[0];
}

int
pic_ungetc(int c, pic_file *file)
{
  return file->ub[file->ur++] = (char)c;
}

int
pic_fputc(int c, pic_file *file)
{
  char buf[1];

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

  return buf[0];
}

int
pic_fputs(const char *str, pic_file *file)
{
  int len;

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

  return 0;
}

static pic_value
port_new_from_fp(pic_state *pic, FILE *fp, short flags)
{
  struct pic_port *port;

  port = (struct pic_port *)pic_obj_alloc(pic, sizeof(struct pic_port), PIC_TT_PORT);
  port->file = pic_funopen(fp, file_read, file_write, file_seek, file_close);
  port->flags = flags;
  port->status = PIC_PORT_OPEN;
  return pic_obj_value(port);
}

static pic_value
port_new_stdio(pic_state *pic, FILE *fp, short dir)
{
  return port_new_from_fp(pic, fp, dir | PIC_PORT_TEXT);
}

static pic_value
pic_port_input_port_p(pic_state *pic)
{
  pic_value v;

  pic_get_args(pic, "o", &v);

  if (pic_port_p(v) && (pic_port_ptr(v)->flags & PIC_PORT_IN) != 0) {
    return pic_true_value();
  }
  else {
    return pic_false_value();
  }
}

static pic_value
pic_port_output_port_p(pic_state *pic)
{
  pic_value v;

  pic_get_args(pic, "o", &v);

  if (pic_port_p(v) && (pic_port_ptr(v)->flags & PIC_PORT_OUT) != 0) {
    return pic_true_value();
  }
  else {
    return pic_false_value();
  }
}

static pic_value
pic_port_textual_port_p(pic_state *pic)
{
  pic_value v;

  pic_get_args(pic, "o", &v);

  if (pic_port_p(v) && (pic_port_ptr(v)->flags & PIC_PORT_TEXT) != 0) {
    return pic_true_value();
  }
  else {
    return pic_false_value();
  }
}

static pic_value
pic_port_binary_port_p(pic_state *pic)
{
  pic_value v;

  pic_get_args(pic, "o", &v);

  if (pic_port_p(v) && (pic_port_ptr(v)->flags & PIC_PORT_BINARY) != 0) {
    return pic_true_value();
  }
  else {
    return pic_false_value();
  }
}

static pic_value
pic_port_port_p(pic_state *pic)
{
  pic_value v;

  pic_get_args(pic, "o", &v);

  return pic_bool_value(pic_port_p(v));
}

static pic_value
pic_port_input_port_open_p(pic_state *pic)
{
  pic_value v;
  struct pic_port *port;

  pic_get_args(pic, "o", &v);

  if (! pic_port_p(v))
    return pic_false_value();
  port = pic_port_ptr(v);
  if ((port->flags & PIC_PORT_IN) == 0)
    return pic_false_value();

  return pic_bool_value(port->status == PIC_PORT_OPEN);
}

static pic_value
pic_port_output_port_open_p(pic_state *pic)
{
  pic_value v;
  struct pic_port *port;

  pic_get_args(pic, "o", &v);

  if (! pic_port_p(v))
    return pic_false_value();
  port = pic_port_ptr(v);
  if ((port->flags & PIC_PORT_OUT) == 0)
    return pic_false_value();

  return pic_bool_value(port->status == PIC_PORT_OPEN);
}

static pic_value
pic_port_eof_object_p(pic_state *pic)
{
  pic_value v;

  pic_get_args(pic, "o", &v);

  if (pic_vtype(v) == PIC_VTYPE_EOF) {
    return pic_true_value();
  }
  else {
    return pic_false_value();
  }
}

static pic_value
pic_port_eof_object(pic_state *pic)
{
  pic_get_args(pic, "");

  return pic_eof_object();
}

static pic_value
pic_port_close_port(pic_state *pic)
{
  struct pic_port *port;

  pic_get_args(pic, "p", &port);

  if (pic_fclose(port->file) == EOF) {
    pic_error(pic, "close-port: failure");
  }
  port->status = PIC_PORT_CLOSE;

  return pic_none_value();
}

#define assert_port_profile(port, flgs, stat, caller) do {              \
    if ((port->flags & (flgs)) != (flgs)) {                             \
      switch (flgs) {                                                   \
      case PIC_PORT_IN:                                                 \
        pic_error(pic, caller ": expected output port");                \
      case PIC_PORT_OUT:                                                \
        pic_error(pic, caller ": expected input port");                 \
      case PIC_PORT_IN | PIC_PORT_TEXT:                                 \
        pic_error(pic, caller ": expected input/textual port");         \
      case PIC_PORT_IN | PIC_PORT_BINARY:                               \
        pic_error(pic, caller ": expected input/binary port");          \
      case PIC_PORT_OUT | PIC_PORT_TEXT:                                \
        pic_error(pic, caller ": expected output/textual port");        \
      case PIC_PORT_OUT | PIC_PORT_BINARY:                              \
        pic_error(pic, caller ": expected output/binary port");         \
      }                                                                 \
    }                                                                   \
    if (port->status != stat) {                                         \
      switch (stat) {                                                   \
      case PIC_PORT_OPEN:                                               \
        pic_error(pic, caller ": expected open port");                  \
      case PIC_PORT_CLOSE:                                              \
        pic_error(pic, caller ": expected close port");                 \
      }                                                                 \
    }                                                                   \
  } while (0)

static pic_value
pic_port_read_char(pic_state *pic)
{
  char c;
  struct pic_port *port = pic_stdin(pic);

  pic_get_args(pic, "|p", &port);

  assert_port_profile(port, PIC_PORT_IN | PIC_PORT_TEXT, PIC_PORT_OPEN, "read-char");

  if ((c = pic_fgetc(port->file)) == EOF) {
    return pic_eof_object();
  }
  else {
    return pic_char_value(c);
  }
}

static pic_value
pic_port_peek_char(pic_state *pic)
{
  char c;
  struct pic_port *port = pic_stdin(pic);

  pic_get_args(pic, "|p", &port);

  assert_port_profile(port, PIC_PORT_IN | PIC_PORT_TEXT, PIC_PORT_OPEN, "peek-char");

  if ((c = pic_fgetc(port->file)) == EOF) {
    return pic_eof_object();
  }
  else {
    pic_ungetc(c, port->file);
    return pic_char_value(c);
  }
}

static pic_value
pic_port_newline(pic_state *pic)
{
  struct pic_port *port = pic_stdout(pic);

  pic_get_args(pic, "|p", &port);

  assert_port_profile(port, PIC_PORT_OUT | PIC_PORT_TEXT, PIC_PORT_OPEN, "newline");

  pic_fputs("\n", port->file);
  return pic_none_value();
}

static pic_value
pic_port_write_char(pic_state *pic)
{
  char c;
  struct pic_port *port = pic_stdout(pic);

  pic_get_args(pic, "c|p", &c, &port);

  assert_port_profile(port, PIC_PORT_OUT | PIC_PORT_TEXT, PIC_PORT_OPEN, "write-char");

  pic_fputc(c, port->file);
  return pic_none_value();
}

static pic_value
pic_port_flush(pic_state *pic)
{
  struct pic_port *port = pic_stdout(pic);

  pic_get_args(pic, "|p", &port);

  assert_port_profile(port, PIC_PORT_OUT, PIC_PORT_OPEN, "flush-output-port");

  pic_fflush(port->file);
  return pic_none_value();
}

void
pic_init_port(pic_state *pic)
{
  pic_defvar(pic, "current-input-port", port_new_stdio(pic, stdin, PIC_PORT_IN));
  pic_defvar(pic, "current-output-port", port_new_stdio(pic, stdout, PIC_PORT_OUT));
  pic_defvar(pic, "current-error-port", port_new_stdio(pic, stderr, PIC_PORT_OUT));

  pic_defun(pic, "input-port?", pic_port_input_port_p);
  pic_defun(pic, "output-port?", pic_port_output_port_p);
  pic_defun(pic, "textual-port?", pic_port_textual_port_p);
  pic_defun(pic, "binary-port?", pic_port_binary_port_p);
  pic_defun(pic, "port?", pic_port_port_p);
  pic_defun(pic, "input-port-open?", pic_port_input_port_open_p);
  pic_defun(pic, "output-port-open?", pic_port_output_port_open_p);
  pic_defun(pic, "eof-object?", pic_port_eof_object_p);
  pic_defun(pic, "eof-object", pic_port_eof_object);
  pic_defun(pic, "close-port", pic_port_close_port);
  pic_defun(pic, "close-input-port", pic_port_close_port);
  pic_defun(pic, "close-output-port", pic_port_close_port);

  /* input */
  pic_defun(pic, "read-char", pic_port_read_char);
  pic_defun(pic, "peek-char", pic_port_peek_char);

  /* write */
  pic_defun(pic, "newline", pic_port_newline);
  pic_defun(pic, "write-char", pic_port_write_char);
  pic_defun(pic, "flush-output-port", pic_port_flush);
}