#include "forth_internal.h"

/**
 * Encode a code point using UTF-8
 *
 * Copied from ESPTERM source
 *
 * @param out - output buffer (min 4 characters), will be 0-terminated if shorten than 4
 * @param utf - code point 0-0x10FFFF
 * @return number of bytes on success, 0 on failure (also produces U+FFFD, which uses 3 bytes)
 */
static int utf8_encode(char *out, uint32_t utf)
{
  if (utf <= 0x7F) {
    // Plain ASCII
    out[0] = (char) utf;
    out[1] = 0;
    return 1;
  } else if (utf <= 0x07FF) {
    // 2-byte unicode
    out[0] = (char) (((utf >> 6) & 0x1F) | 0xC0);
    out[1] = (char) (((utf >> 0) & 0x3F) | 0x80);
    out[2] = 0;
    return 2;
  } else if (utf <= 0xFFFF) {
    // 3-byte unicode
    out[0] = (char) (((utf >> 12) & 0x0F) | 0xE0);
    out[1] = (char) (((utf >> 6) & 0x3F) | 0x80);
    out[2] = (char) (((utf >> 0) & 0x3F) | 0x80);
    out[3] = 0;
    return 3;
  } else if (utf <= 0x10FFFF) {
    // 4-byte unicode
    out[0] = (char) (((utf >> 18) & 0x07) | 0xF0);
    out[1] = (char) (((utf >> 12) & 0x3F) | 0x80);
    out[2] = (char) (((utf >> 6) & 0x3F) | 0x80);
    out[3] = (char) (((utf >> 0) & 0x3F) | 0x80);
//		out[4] = 0;
    return 4;
  } else {
    // error - use replacement character
    out[0] = (char) 0xEF;
    out[1] = (char) 0xBF;
    out[2] = (char) 0xBD;
    out[3] = 0;
    return 0;
  }
}


static enum fh_error w_dot(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  uint32_t a = 0;
  TRY(ds_pop(fh, &a));

  FHPRINT("%d ", (int32_t) a);
  return FH_OK;
}

static enum fh_error w_u_r(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  uint32_t a = 0, n = 0;
  TRY(ds_pop(fh, &n));
  TRY(ds_pop(fh, &a));

  FHPRINT("%*d", n, a);
  return FH_OK;
}

static enum fh_error w_type(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  uint32_t count = 0, addr = 0;
  LOG("Get count,addr");
  TRY(ds_pop(fh, &count));
  TRY(ds_pop(fh, &addr));

  const char *str = fh_str_at(fh, addr);
  if (!str) {
    LOGE("Type addr out of bounds!");
    return FH_ERR_NOT_APPLICABLE;
  }
  FHPRINT("%.*s", count, str);
  return FH_OK;
}

static enum fh_error wp_putc(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) fh;
  FHPRINT("%c", w->param);
  return FH_OK;
}

static enum fh_error w_debug_dump(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  (void) fh;

  FHPRINT("DS ");
  for (int i = 0; i < fh->data_stack_top; i++) {
    FHPRINT("%d ", fh->data_stack[i]);
  }

  FHPRINT("\nRS ");
  for (int i = 0; i < fh->return_stack_top; i++) {
    FHPRINT("%d ", fh->return_stack[i]);
  }

  FHPRINT("\n");
  return FH_OK;
}

static enum fh_error w_emit(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  uint32_t a;
  TRY(ds_pop(fh, &a));

  char buf[5];
  int num = utf8_encode(buf, a);
  FHPRINT("%.*s", num, buf);
  return FH_OK;
}

static enum fh_error w_see(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  enum fh_error rv;
  char *wordname;
  size_t namelen = 0;
  fh_input_consume_spaces(fh);
  TRY(fh_input_read_word(fh, &wordname, &namelen));
  TRY(fh_see_word(fh, wordname, namelen));
  return FH_OK;
}

static enum fh_error w_s_quote(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  size_t len;
  uint32_t addr = fh->here + (fh->state == FH_STATE_INTERPRET ? 0 : INSTR_SIZE);

  /* read the string straight into HEAP */

  fh_input_consume_spaces(fh);
  char *start = (char *) &fh->heap[addr];
  TRY(fh_input_read_quotedstring(fh, w->param == 1, start, HEAP_END - addr, &len));
  fh->here = WORDALIGNED(addr + len);

  struct fh_instruction_s instr;
  if (fh->state == FH_STATE_INTERPRET) {
    LOG("Interpret a string alloc: \"%.*s\"", len, start);
    TRY(ds_push(fh, addr));
    TRY(ds_push(fh, len));
  } else {
    LOG("Compile a string: \"%.*s\"", len, start);
    instr.kind = FH_INSTR_ALLOCSTR;
    instr.data = len;
    fh_heap_write(fh, addr - INSTR_SIZE, &instr, INSTR_SIZE);
  }

  return FH_OK;
}

static bool chartest_equals_or_end(char c, void *param)
{
  char cc = *(char*)param;
  return cc == c || c == 0;
}

static enum fh_error w_dot_quote(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  size_t len;

  // leave space for the instr in case of compiled version
  uint32_t addr = fh->here + (fh->state == FH_STATE_INTERPRET ? 0 : INSTR_SIZE);

  /* read the string straight into HEAP, but don't advance the heap pointer, so the string is immediately discarded again */

  fh_input_consume_spaces(fh);
  char *start;
  char c = (char)w->param;
  uint32_t capacity = HEAP_END - addr;
  if (c == '\\') {
    start = (char *) &fh->heap[addr];
    TRY(fh_input_read_quotedstring(fh, 1, start, capacity, &len));
  } else {
    start = NULL;
    TRY(fh_input_read_delimited(fh, &start, &len, chartest_equals_or_end, &c));
    if (len > capacity) {
      LOGE("String too low for heap");
      return FH_ERR_HEAP_FULL;
    }
    if (fh->state == FH_STATE_COMPILE) {
      fh_heap_copyptr(fh, addr, start, len);
    }
  }

  struct fh_instruction_s instr;
  if (fh->state == FH_STATE_INTERPRET) {
    FHPRINT("%.*s", (int) len, start);
    // the string is invalidated immediately, heap pointer is NOT advanced.
  } else {
    LOG("Compile a string: \"%.*s\"", len, start);
    TRY(fh_put_instr(fh, FH_INSTR_TYPESTR, len));
    fh->here = WORDALIGNED(addr + len); // at the end of the string
  }

  return FH_OK;
}

static enum fh_error w_less_hash(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  fh->pictnumptr = WORDBUF_LASTCHAR_ADDR;
  return FH_OK;
}

static enum fh_error w_hash_greater(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  
  
  uint64_t dummy;
  TRY(ds_pop_dw(fh, &dummy));
  
  uint32_t len = WORDBUF_LASTCHAR_ADDR - fh->pictnumptr;
  uint32_t addr;
  TRY(fh_heap_reserve(fh, len, &addr));
  fh_heap_copy(fh, addr, fh->pictnumptr+1, len);
  LOG("#> output: \"%.*s\"", len, &fh->heap[fh->pictnumptr+1]);
  TRY(ds_push(fh, addr));
  TRY(ds_push(fh, len));
  return FH_OK;
}

static enum fh_error pictnum_prepend_char(struct fh_thread_s *fh, char c) {
  enum fh_error rv;
  if (fh->pictnumptr < WORDBUF_ADDR) {
    return FH_ERR_PICTNUM_FULL;
  }
  LOG("Prepend: %c", c);
  TRY(fh_store_char(fh, fh->pictnumptr, c));
  fh->pictnumptr--;
  return FH_OK;
}

static char dig2char(uint64_t digit) {
  char repr;
  if (digit < 10) {
    repr = '0' + digit;
  } else if (digit < 36) {
    repr = 'A' + (digit - 10);
  } else {
    repr = '?'; // XXX bad base?
  }
  return repr;
}

static enum fh_error w_hash(struct fh_thread_s *fh, const struct fh_word_s *w)
{  
  (void) w;
  enum fh_error rv;
  uint64_t num;
  TRY(ds_pop_dw(fh, &num));
  uint64_t digit = num % fh->base;
  TRY(pictnum_prepend_char(fh, dig2char(digit)));
  TRY(ds_push_dw(fh, num / (uint64_t)fh->base));
  return FH_OK;
}

static enum fh_error w_hash_s(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  uint64_t num;
  TRY(ds_pop_dw(fh, &num));
  
  do {
    uint64_t digit = num % fh->base;
    num = num / (uint64_t)fh->base;    
    TRY(pictnum_prepend_char(fh, dig2char(digit)));
  } while (num > 0);
  
  TRY(ds_push_dw(fh, num)); // this is zero now
  return FH_OK;
}

static enum fh_error w_sign(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  uint32_t num;
  TRY(ds_pop(fh, &num));
  if ((int32_t)num < 0) {
    TRY(pictnum_prepend_char(fh, '-'));
  }
  return FH_OK;
}

static enum fh_error w_hold(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  uint32_t ch;
  TRY(ds_pop(fh, &ch));
  
  char buf[5];
  int num = utf8_encode(buf, ch);
  for(int i=num-1;i>=0;i--) {
    TRY(pictnum_prepend_char(fh, buf[i]));
  }
  return FH_OK;
}

static enum fh_error w_holds(struct fh_thread_s *fh, const struct fh_word_s *w)
{
  (void) w;
  enum fh_error rv;
  uint32_t ch;
  
  uint32_t count = 0, addr = 0;
  LOG("Get count,addr");
  TRY(ds_pop(fh, &count));
  TRY(ds_pop(fh, &addr));

  const char *str = fh_str_at(fh, addr);
  if (!str) {
    LOGE("HOLDS addr out of bounds!");
    return FH_ERR_NOT_APPLICABLE;
  }
  
  for(int i=count-1;i>=0;i--) {
    TRY(pictnum_prepend_char(fh, str[i]));
  }  
  
  return FH_OK;
}

const struct name_and_handler fh_builtins_text[] = {
    {"s\"",   w_s_quote,    1, 0},
    {"s\\\"", w_s_quote,    1, 1}, // escaped
    {".\"",   w_dot_quote,  1, '"'},
    {".(",    w_dot_quote,   1, ')'},
    {".\\\"", w_dot_quote,  1, '\\'}, // escaped, this is non-standard
    {".",     w_dot,        0, 0},
    {"type",  w_type,       0, 0},
    {"cr",    wp_putc,      0, '\n'},
    {"space", wp_putc,      0, ' '},
    {"bl",    wp_const,     0, ' '},
    {"u.r",   w_u_r,        0, 0},
    {"??",    w_debug_dump, 0, 0},
    {"emit",  w_emit,       0, 0},
    {"see",   w_see,        0, 0},
    {"<#",    w_less_hash,  0, 0},
    {"#>",    w_hash_greater,  0, 0},
    {"#",     w_hash,       0, 0},
    {"#s",     w_hash_s,       0, 0},
    {"sign",     w_sign,       0, 0},
    {"hold",     w_hold,       0, 0},
    {"holds",     w_holds,       0, 0},
    { /* end marker */ }
};