#include "forth_internal.h"

/** True if the character is CR or LF */
static inline bool isnl(char c)
{
  return c == '\n' || c == '\r';
}

static const char * strnchr(const char* s, char c, size_t len)
{
  while (len > 0) {
    char x = *s;
    if (!x) {
      break;
    }
    if (x == c) {
      return s;
    }
    s++;
    len--;
  }
  return NULL;
}

/** Process a word read from input */
enum fh_error fh_handle_ascii_word(
    struct fh_thread_s *fh,
    const char *name,
    const size_t wordlen
)
{
  enum fh_error rv;
  if (wordlen >= MAX_NAME_LEN) {
    return FH_ERR_NAME_TOO_LONG;
  }

  /* First, try if it's a known word */

  uint32_t wadr = 0;
  if (FH_OK == fh_find_word(fh, name, wordlen, &wadr)) {
    TRY(fh_handle_word(fh, wadr));
    return FH_OK;
  }

  /* word not found, try parsing as number */
  errno = 0;
  char *endptr;
  int base = (int) fh->base;

  // prefix can override BASE - this is a syntax extension
  if (name[0] == '0') {
    if (name[1] == 'x') {
      base = 16;
    } else if (name[1] == 'b') {
      base = 2;
    } else if (name[1] == 'o') {
      base = 8;
    }
  }

  long v = strtol(name, &endptr, base); // if base is 0, this will use auto-detection
  if (errno != 0 || (endptr - name) != wordlen) {
    LOGE("Unknown word and fail to parse as number: \"%.*s\", len %d", (int) wordlen, name, wordlen);
    return FH_ERR_UNKNOWN_WORD;
  }

  if (fh->state == FH_STATE_COMPILE) {
    LOG("\x1b[34m[COM] Compile number:\x1b[m %ld", v);
    TRY(fh_put_instr(fh, FH_INSTR_NUMBER, (uint32_t) v));
  } else {
    /* interpret */
    LOG("\x1b[35m[INT] Push number:\x1b[m %ld", v);
    TRY(ds_push(fh, (uint32_t) v));
  }

  return FH_OK;
}


void fh_input_consume_matching(struct fh_thread_s *fh, chartest_t test, void *param)
{
  char *rp = (char *) &fh->heap[fh->inputaddr + fh->inputptr];
  while (test(*rp, param)) {
    rp++;
    fh->inputptr++;
  }
}

void fh_input_consume_spaces(struct fh_thread_s *fh)
{
  char *rp = (char *) &fh->heap[fh->inputaddr + fh->inputptr];
  while (isspace(*rp)) {
    rp++;
    fh->inputptr++;
  }
}

enum fh_error fh_input_read_delimited(struct fh_thread_s *fh, char **out, size_t *len, chartest_t test, void *param)
{
  char *rp = (char *) &fh->heap[fh->inputaddr + fh->inputptr];
  char *start = rp;
  while (fh->inputptr < fh->inputlen) {
    char c = *rp;
    if (test(c, param)) {
      if (rp == start) {
        // nothing was found, this is probably OK.        
        LOG("Parsed an empty word");
      }
      *out = start;
      *len = rp - start;
      fh->inputptr++; // advance past the delimiter
      return FH_OK;
    }
    rp++;
    fh->inputptr++;
  }
  *out = start;
  *len = rp - start;
  return FH_OK;
}

bool fh_chartest_space_or_end(char c, void *param)
{
  (void) param;
  return isspace(c) || c == 0;
}

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

enum fh_error fh_input_read_word(struct fh_thread_s *fh, char **out, size_t *len)
{
  return fh_input_read_delimited(fh, out, len, fh_chartest_space_or_end, NULL);
}

enum fh_error fh_input_read_quotedstring(struct fh_thread_s *fh, bool escaped, char *outbuf, size_t capacity, size_t *out_len)
{
  char *rp = (char *) &fh->heap[fh->inputaddr + fh->inputptr];
  bool next_escaped = false;
  size_t remains = capacity;
  size_t len = 0;
  int hexdigits = 0;
  uint32_t hex = 0;
  while (len < capacity) {
    char c = *rp;
    if (c == 0) {
      LOGE("Unterminated quoted string!");
      return FH_ERR_SYNTAX;
    }

    if (hexdigits) {
      hex <<= 4;
      if (isdigit(c)) {
        hex |= c - '0';
      } else if (c >= 'a' && c <= 'f') {
        hex |= 10 + (c - 'a');
      } else if (c >= 'A' && c <= 'F') {
        hex |= 10 + (c - 'A');
      } else {
        LOGE("Bad hex escape");
        return FH_ERR_SYNTAX;
      }
      hexdigits--;
      if (hexdigits == 0) {
        c = (char) hex;
        goto append;
      } else {
        goto skip;
      }
    }

    if (!escaped || !next_escaped) {
      if (c == '\"') {
        *outbuf = 0;
        *out_len = len;
        // advance past the quote
        fh->inputptr++;
        return FH_OK;
      }

      if (c == '\\') {
        next_escaped = true;
        goto skip;
      }
    } else {
      next_escaped = false;
      switch (c) {
        case 'a':
          c = 7;
          break;
        case 'b':
          c = 8;
          break;
        case 'e':
          c = 27;
          break;
        case 'f':
          c = 12;
          break;
        case 'l':
          c = 10;
          break;
        case 'm':
        case 'n':
          if (remains < 2) { goto full; }
          *outbuf++ = '\r';
          *outbuf++ = '\n';
          remains -= 2;
          len += 2;
          goto skip;
        case 'q':
          c = '"';
          break;
        case 'r':
          c = '\r';
          break;
        case 't':
          c = '\t';
          break;
        case 'v':
          c = '\v';
          break;
        case 'z':
          c = 0;
          break; // this will cause problems with string printing
        case 'x':
          hex = 0;
          hexdigits = 2;
          goto skip;
        default:;
          // just append normally
      }
    }

    append:
    *outbuf++ = c;
    len++;
    skip:
    rp++;
    fh->inputptr++;
  }

  full:
  LOGE("String too long!");
  return FH_ERR_SYNTAX;
}

enum fh_error fh_process_line(struct fh_thread_s *fh);

enum fh_error fh_runtime_start(struct fh_thread_s *fh, struct fh_input_spec_s *input)
{
  enum fh_error rv;
  void *original_input = fh->input;
  TRY(fh_push_input(fh, input));

  if (fh_globals.interactive) {
    FHPRINT("%s", FH_PROMPT_STR);
  }

  input->start(fh, input);

  while (1) {
    //LOG("Refill input buffer");
    if (fh->input->refill_input_buffer(fh, fh->input)) {
      // discard spaces at the end
      while (isspace(fh->heap[fh->inputaddr + fh->inputlen - 1]) && fh->inputlen > 0) {
        fh->heap[fh->inputaddr + fh->inputlen - 1] = 0;
        fh->inputlen--;
      }

      if (fh->inputlen == 0) {
        continue;
      }

      rv = fh_process_line(fh);

      if (rv == FH_OK) {
        if (fh->state == FH_STATE_SHUTDOWN) {
          return FH_OK;
        }
        if (fh_globals.interactive || fh_globals.echo) {
          FHPRINT_SVC(" ok\n");
        }
      } else {        
        LOGE("Error %s on line %d in source %d", fherr_name(rv), fh->input->linenum, fh->input->source_id);
        if (fh_globals.interactive || fh_globals.rescue) {
          LOGE("Drop to interactive");
          fh_drop_to_interactive(fh);
        } else {
          LOGE("Shutting down due to error");
          fh->state = FH_STATE_SHUTDOWN;
          return FH_OK;
        }
      }

      if (fh_globals.interactive) {
        FHPRINT("%s", FH_PROMPT_STR);
      }

    } else {
      LOG("Pop input");
      TRY(fh_pop_input(fh));
      if (fh->input == original_input || !fh->input) {
        // we are done
        break;
      }
    }
  }
  return FH_OK;
}

/** Process a line read from input */
enum fh_error fh_process_line(struct fh_thread_s *fh)
{
  enum fh_error rv;

#define ReadPtr ((char*)(&fh->heap[fh->inputaddr + fh->inputptr]))
#define ReadPos (fh->inputptr)
#define ReadLen (fh->inputlen)

  //fh_fill_input_buffer(fh, linebuf, len);

  char c;

  if (fh_globals.echo && !fh_globals.interactive) {
    LOGI("%.*s", ReadLen, ReadPtr);
  }

  while (ReadPos < ReadLen && fh->state != FH_STATE_SHUTDOWN) {
    c = *ReadPtr;
    /* end on newline */
    if (isnl(c)) {
      goto done;
    }
    /* skip whitespace */
    if (isspace(c)) {
      ReadPos++;
      continue;
    }

    const char *const rp = ReadPtr;

    const char *end;
    size_t length;
    switch (fh->substate) {
      case FH_SUBSTATE_NONE:
        /* try to read a word */
        size_t maxlen = ReadLen - ReadPos;
        end = strnchr(rp, ' ', maxlen);
        if (end) {
          length = end - rp; /* exclude the space */
        } else {
          length = strnlen(rp, maxlen);
        }

        ReadPos += length + 1;

        if (EQ(rp, "[if]", length)) {
          if (0 == fh->parse_if_level) {
            uint32_t val;
            TRY(ds_pop(fh, &val));
            if (!val) {
              LOG("\x1b[32m[if] false, start skipping\x1b[m");
              fh->parse_if_level++;
            } else {
              LOG("\x1b[32m[if] true, proceed\x1b[m");
            }
          } else {
            LOG("\x1b[32m[if] nest+\x1b[m");
            fh->parse_if_level++;
          }
        } else if (EQ(rp, "[else]", length)) {
          if (fh->parse_if_level == 1) {
            // we got here by running the [if] branch
            LOG("\x1b[3m[else] end of false skip\x1b[m");
            fh->parse_if_level--;
          }
        } else if (EQ(rp, "[then]", length)) {
          if (fh->parse_if_level > 0) {
            fh->parse_if_level--;
            if (fh->parse_if_level == 0) {
              LOG("\x1b[32m[then] end of skipped section\x1b[m");
            } else {
              LOG("\x1b[32m[then] nest-\x1b[m");
            }
          } else {
            LOG("\x1b[32m[then] end of conditional\x1b[m");
          }
        } else if (fh->parse_if_level == 0) {
          /* eval a word */
          LOG("Handle \"%.*s\"", (int) length, rp);
          TRY(fh_handle_ascii_word(fh, rp, length));
        } else {
          if (EQ(rp, "\\", length)) {
            // discard to EOL
//             LOG("Discard \"%.*s\"", (int)(fh->inputlen - fh->inputptr + length), rp);
            goto done;
          }

          LOG("Discard \"%.*s\"", (int) length, rp);
        }
        break;

      case FH_SUBSTATE_PAREN_COMMENT:
        end = strchr(rp, ')');
        if (end) {
          length = end - rp;
          LOG("Discard inline comment: \"%.*s\"", (int)length, rp);
          fh_setsubstate(fh, FH_SUBSTATE_NONE);
          ReadPos += length + 1;
        } else {
          /* no end, discard all */
          LOGE("Unterminated parenthesis comment");
          goto done;
        }
        break;

      case FH_SUBSTATE_LINE_COMMENT:
        LOG("Discard line comment: \"%.*s\"", fh->inputlen - fh->inputptr, rp);
        fh_setsubstate(fh, 0);
        goto done; // just discard the rest

      default:
        LOGE("Bad substate %s", substatenames[fh->substate]);
    }
  }
  done:
  LOG("Line done, rp %d, len %d", ReadPos, ReadLen);
  return FH_OK;
}