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

#include "picrin.h"
#include "value.h"
#include "object.h"

static void dump1(unsigned char c, unsigned char *buf, int *len) {
  if (buf) {
    buf[*len] = c;
  }
  *len = *len + 1;
}

static void dump4(unsigned long n, unsigned char *buf, int *len) {
  assert(sizeof(long) * CHAR_BIT <= 32 || n <= 0xfffffffful);

  dump1((n & 0xff), buf, len);
  dump1((n & 0xff00) >> 8, buf, len);
  dump1((n & 0xff0000) >> 16, buf, len);
  dump1((n & 0xff000000) >> 24, buf, len);
}

static void dump_obj(pic_state *pic, pic_value obj, unsigned char *buf, int *len);

#define IREP_FLAGS_MASK (IREP_VARG)

static void
dump_irep(pic_state *pic, struct irep *irep, unsigned char *buf, int *len)
{
  size_t i;
  dump1(irep->argc, buf, len);
  dump1(irep->flags & IREP_FLAGS_MASK, buf, len);
  dump1(irep->frame_size, buf, len);
  dump1(irep->irepc, buf, len);
  dump1(irep->objc, buf, len);
  dump4(irep->codec, buf, len);
  for (i = 0; i < irep->objc; ++i) {
    dump_obj(pic, irep->obj[i], buf, len);
  }
  for (i = 0; i < irep->codec; ++i) {
    dump1(irep->code[i], buf, len);
  }
  for (i = 0; i < irep->irepc; ++i) {
    dump_irep(pic, irep->irep[i], buf, len);
  }
}

static void
dump_obj(pic_state *pic, pic_value obj, unsigned char *buf, int *len)
{
  if (pic_int_p(pic, obj)) {
    dump1(0x00, buf, len);
    dump4(pic_int(pic, obj), buf, len);
  } else if (pic_str_p(pic, obj)) {
    int l, i;
    const char *str = pic_str(pic, obj, &l);
    dump1(0x01, buf, len);
    dump4(l, buf, len);
    for (i = 0; i < l; ++i) {
      dump1(str[i], buf, len);
    }
    dump1(0, buf, len);
  } else if (pic_sym_p(pic, obj)) {
    int l, i;
    const char *str = pic_str(pic, pic_sym_name(pic, obj), &l);
    dump1(0x02, buf, len);
    dump4(l, buf, len);
    for (i = 0; i < l; ++i) {
      dump1(str[i], buf, len);
    }
    dump1(0, buf, len);
  } else if (pic_proc_p(pic, obj)) {
    if (pic_proc_func_p(pic, obj)) {
      pic_error(pic, "dump: c function procedure serialization unsupported", 1, obj);
    }
    if (proc_ptr(pic, obj)->env) {
      pic_error(pic, "dump: local procedure serialization unsupported", 1, obj);
    }
    dump1(0x03, buf, len);
    dump_irep(pic, proc_ptr(pic, obj)->u.irep, buf, len);
  } else if (pic_char_p(pic, obj)) {
    dump1(0x04, buf, len);
    dump1(pic_char(pic, obj), buf, len);
  } else {
    pic_error(pic, "dump: unsupported object", 1, obj);
  }
}

pic_value
pic_serialize(pic_state *pic, pic_value obj)
{
  int len = 0;
  pic_value blob;
  dump_obj(pic, obj, NULL, &len);
  blob = pic_blob_value(pic, NULL, len);
  len = 0;
  dump_obj(pic, obj, pic_blob(pic, blob, NULL), &len);
  return blob;
}

static void loadn(pic_state *pic, unsigned char *dst, size_t size, const unsigned char **buf, const unsigned char *end) {
  if (*buf + size > end) {
    pic_error(pic, "malformed bytevector", 0);
  }
  memcpy(dst, *buf, size);
  *buf = *buf + size;
}

static unsigned char load1(pic_state *pic, const unsigned char **buf, const unsigned char *end) {
  unsigned char c;
  loadn(pic, &c, 1, buf, end);
  return c;
}

static unsigned long load4(pic_state *pic, const unsigned char **buf, const unsigned char *end) {
  unsigned long x = load1(pic, buf, end);
  x += load1(pic, buf, end) << 8;
  x += load1(pic, buf, end) << 16;
  x += load1(pic, buf, end) << 24;
  return x;
}

static pic_value load_obj(pic_state *pic, const unsigned char **buf, const unsigned char *end);

static struct irep *
load_irep(pic_state *pic, const unsigned char **buf, const unsigned char *end)
{
  unsigned char argc, flags, frame_size, irepc, objc;
  size_t codec, i;
  pic_value *obj;
  unsigned char *code;
  struct irep **irep, *ir;
  size_t ai = pic_enter(pic);

  argc = load1(pic, buf, end);
  flags = load1(pic, buf, end);
  frame_size = load1(pic, buf, end);
  irepc = load1(pic, buf, end);
  objc = load1(pic, buf, end);
  codec = load4(pic, buf, end);
  obj = pic_malloc(pic, sizeof(pic_value) * objc);
  for (i = 0; i < objc; ++i) {
    obj[i] = load_obj(pic, buf, end);
  }
  code = pic_malloc(pic, codec); /* TODO */
  loadn(pic, code, codec, buf, end);
  irep = pic_malloc(pic, sizeof(struct irep *) * irepc);
  for (i = 0; i < irepc; ++i) {
    irep[i] = load_irep(pic, buf, end);
  }
  ir = (struct irep *) pic_obj_alloc(pic, PIC_TYPE_IREP);
  ir->argc = argc;
  ir->flags = flags;
  ir->frame_size = frame_size;
  ir->irepc = irepc;
  ir->objc = objc;
  ir->codec = codec;
  ir->obj = obj;
  ir->code = code;
  ir->irep = irep;
  pic_leave(pic, ai);
  pic_protect(pic, obj_value(pic, ir));
  return ir;
}

static pic_value
load_obj(pic_state *pic, const unsigned char **buf, const unsigned char *end)
{
  int type, l;
  pic_value obj;
  char *dat, c;
  struct irep *irep;
  struct proc *proc;
  type = load1(pic, buf, end);
  switch (type) {
  case 0x00:
    return pic_int_value(pic, load4(pic, buf, end));
  case 0x01:
    l = load4(pic, buf, end);
    dat = pic_malloc(pic, l + 1); /* TODO */
    loadn(pic, (unsigned char *) dat, l + 1, buf, end);
    obj = pic_str_value(pic, dat, l);
    pic_free(pic, dat);
    return obj;
  case 0x02:
    l = load4(pic, buf, end);
    dat = pic_malloc(pic, l + 1); /* TODO */
    loadn(pic, (unsigned char *) dat, l + 1, buf, end);
    obj = pic_intern_str(pic, dat, l);
    pic_free(pic, dat);
    return obj;
  case 0x03:
    irep = load_irep(pic, buf, end);
    proc = (struct proc *)pic_obj_alloc(pic, PIC_TYPE_PROC_IREP);
    proc->u.irep = irep;
    proc->env = NULL;
    return obj_value(pic, proc);
  case 0x04:
    c = load1(pic, buf, end);
    return pic_char_value(pic, c);
  default:
    pic_error(pic, "load: unsupported object", 1, pic_int_value(pic, type));
  }
}

pic_value
pic_deserialize(pic_state *pic, pic_value blob)
{
  int len;
  const unsigned char *buf = pic_blob(pic, blob, &len);
  return load_obj(pic, &buf, buf + len);
}