#include "forth_internal.h"

struct fh_global_s fh_globals = {};

/** State names */
static const char *statenames[FH_STATE_MAX] = {
    [FH_STATE_INTERPRET] = "INTERPRET",
    [FH_STATE_COMPILE] = "COMPILE",
    [FH_STATE_QUIT] = "QUIT",
    [FH_STATE_SHUTDOWN] = "SHUTDOWN",
};

/** State names short */
static const char *stateshort[FH_STATE_MAX] = {
    [FH_STATE_INTERPRET] = "INT",
    [FH_STATE_COMPILE] = "COM",
    [FH_STATE_QUIT] = "QIT",
    [FH_STATE_SHUTDOWN] = "DIE",
};

/** Sub-state names */
const char *substatenames[FH_SUBSTATE_MAX] = {
    [FH_SUBSTATE_NONE] = "NONE",
    [FH_SUBSTATE_PAREN_COMMENT] = "PAREN_COMMENT",
    [FH_SUBSTATE_LINE_COMMENT] = "LINE_COMMENT",
    [FH_SUBSTATE_EXIT] = "EXIT",
    [FH_SUBSTATE_SKIP_IF] = "SKIP_IF",
};

/** Sub-state names */
static const char *instrnames[FH_INSTR_MAX] = {
    [FH_INSTR_WORD] = "WORD",
    [FH_INSTR_NUMBER] = "NUMBER",
    [FH_INSTR_ENDWORD] = "ENDWORD",
    [FH_INSTR_ALLOCSTR] = "ALLOCSTR",
    [FH_INSTR_TYPESTR] = "TYPESTR",
    [FH_INSTR_JUMP] = "JUMP",
    [FH_INSTR_JUMPZERO] = "JUMPZERO",
    [FH_INSTR_LEAVE] = "LEAVE",
    [FH_INSTR_DO] = "DO",
    [FH_INSTR_TO] = "TO",
    [FH_INSTR_DO_QUESTION] = "DO_QUESTION",
    [FH_INSTR_LOOP] = "LOOP",
    [FH_INSTR_LOOP_PLUS] = "LOOP_PLUS",
    [FH_INSTR_POSTPONED_WORD] = "POSTPONED_WORD",
    [FH_INSTR_ABORTSTR] = "ABORTSTR",
    [FH_INSTR_ACTIONOF] = "ACTIONOF",
    [FH_INSTR_ISDEFER] = "ISDEFER",
};

void fh_abort(struct fh_thread_s *fh) {
  fh->data_stack_top = 0;
  fh_quit(fh);
}

void fh_drop_to_interactive(struct fh_thread_s *fh) {
  fh_input_teardown(fh);
  
  fh_push_input(fh, fh_create_input_from_filestruct(stdin, NULL));
  fh->return_stack_top = 0; 
  fh->execptr = MAGICADDR_EXEC_INTERACTIVE;
  fh_globals.interactive = 1;
  fh_setstate(fh, FH_STATE_INTERPRET, 0);
}

void fh_quit(struct fh_thread_s *fh) {
  if (fh_globals.interactive || fh_globals.rescue) {
    fh_drop_to_interactive(fh);
    fh_setstate(fh, FH_STATE_QUIT, 0);
  } else {
    fh_setstate(fh, FH_STATE_SHUTDOWN, 0);
  }
}

const char *instr_name(enum fh_instruction_kind kind)
{
  if (kind >= FH_INSTR_MAX) {
    return "Unknown";
  } else {
    return instrnames[kind];
  }
}

/** Add a word to the dictionary. */
enum fh_error fh_add_word(const struct fh_word_s *w, struct fh_thread_s *fh)
{
  enum fh_error rv;

  fh_align(fh);
  uint32_t ptr = fh->here;

  TRY(fh_heap_put(fh, w, DICTWORD_SIZE));

  //LOG("Added word \"%s\" at 0x%08x", w->name, ptr);

  // thread it onto the linked list
  struct fh_word_s *word = fh_word_at(fh, ptr);
  if (!word) { return FH_ERR_INTERNAL; }
  word->previous = fh->dict_last;
  fh->dict_last = ptr;

  return FH_OK;
}

/** Log current runtime state */
static void showstate(const struct fh_thread_s *fh)
{
  if (fh->substate == 0) {
    LOG("state -> %s", statenames[fh->state]);
  } else {
    LOG("state -> %s.%s", statenames[fh->state], substatenames[fh->substate]);
  }
}

/** Set runtime state and sub-state */
void fh_setstate(struct fh_thread_s *fh, enum fh_state state, enum fh_substate substate)
{
  fh->state = state;
  fh->substate = substate;
  showstate(fh);
}

/** Set runtime sub-state (state is unchanged) */
void fh_setsubstate(struct fh_thread_s *fh, enum fh_substate substate)
{
  fh->substate = substate;
  showstate(fh);
}

/** Execute a user word */
enum fh_error w_user_word(struct fh_thread_s *fh, const struct fh_word_s *w0)
{
  enum fh_error rv;
  const struct fh_word_s *w;
  struct fh_word_s *w2;

  fh->executing_compiled = 1;

  w = w0;
  call:
  if (!w) { return FH_ERR_INTERNAL; }

  LOG("\x1b[35mExec: Called user word: %s\x1b[m", w->name);

  TRY(rs_push(fh, fh->execptr));
  fh->execptr = w->param;

  if ((WORDFLAG_WORD | WORDFLAG_CREATED) == (w->flags & (WORDFLAG_WORD | WORDFLAG_CREATED))) {
    // push the >BODY addr if this is a CREATE'd word
    TRY(ds_push(fh, word_addr(fh, w) + DICTWORD_SIZE));
  }

  instr:;
  if (fh->state == FH_STATE_SHUTDOWN) {
    return FH_OK;
  }
  if (fh->state == FH_STATE_QUIT) {
    LOG("QUIT word exec");
    /* abort or quit was called, return to interactive mode */
    fh_setstate(fh, FH_STATE_INTERPRET, FH_SUBSTATE_NONE);
    return FH_OK;
  }
  // make sure it's aligned
  fh->execptr = WORDALIGNED(fh->execptr);
  
  if (fh->execptr == 0 || fh->execptr > fh->here) {
    LOGE("Bad execptr value 0x%08x", fh->execptr);
    return FH_ERR_ILLEGAL_FETCH;
  }
  
  const struct fh_instruction_s *instr = fh_instr_at(fh, fh->execptr);
  if (!instr) {
    LOGE("Execution pointer out of bounds!");
    return FH_ERR_INTERNAL;
  }
  fh->execptr += INSTR_SIZE;

  uint32_t strl;
  uint32_t val, testval;
  uint32_t limit, index;

  LOG("0x%08x: Instr %s, 0x%08x", fh->execptr, instr_name(instr->kind), instr->data);

  switch (instr->kind) {
    case FH_INSTR_NUMBER:
      TRY(ds_push(fh, instr->data));
      goto instr;

    case FH_INSTR_POSTPONED_WORD:
      //if (fh->state == FH_STATE_COMPILE) {
      w2 = fh_word_at(fh, instr->data);
      if (!w2) {
        LOGE("Postponed bad word addr!");
        return FH_ERR_INTERNAL;
      }
      if (w2->flags & WORDFLAG_IMMEDIATE) {
        goto call_w2;
//          LOG("Call immediate postponed word: %s", w2->name);
//          if (w2->flags & WORDFLAG_BUILTIN) {
//            TRY(rs_push(fh, fh->execptr));
//          }
//          TRY(w2->handler(fh, w2));
//          if (0 == (w2->flags & WORDFLAG_BUILTIN)) {
//            TRY(rs_pop(fh, &fh->execptr));
//          }
      } else {
        LOG("\x1b[35mExec: Add postponed word\x1b[m %s", w2->name);
        TRY(fh_put_instr(fh, FH_INSTR_WORD, instr->data));
      }
      /*} else {
        LOGE("Postpone in interpret mode!");
        goto end;
      }*/
      goto instr;

    case FH_INSTR_WORD:
      w2 = fh_word_at(fh, instr->data);
      if (!w2) {
        LOGE("Instr bad word addr!");
        return FH_ERR_INTERNAL;
      }
    call_w2:
      if (w2->flags & WORDFLAG_BUILTIN) {
        LOG("\x1b[35mExec: native-word \"%s\"\x1b[m", w2->name);
        TRY(w2->handler(fh, w2));
        if (fh->substate == FH_SUBSTATE_EXIT) {
          fh_setsubstate(fh, 0);
          LOG("Exec: early return");
          TRY(rs_pop(fh, &fh->execptr));
          if (fh->execptr == MAGICADDR_EXEC_INTERACTIVE) {
            goto end;
          }
        }
        goto instr;
      } else {
        LOG("\x1b[35mExec: user-word %s\x1b[m (CALL)", w2->name);
        w = fh_word_at(fh, instr->data);
        if (!w) {
          LOGE("CALL instr bad word addr!");
          return FH_ERR_INTERNAL;
        }
        goto call;
      }

    case FH_INSTR_JUMPZERO:
      LOG("\x1b[35mExec: jump if zero -> 0x%08x\x1b[m", instr->data);
      if (instr->data == MAGICADDR_UNRESOLVED) {
        LOGE("Encountered unresolved jump!");
        goto end;
      }

      TRY(ds_pop(fh, &val));
      if (0 == val) {
        LOG("Jumping");
        fh->execptr = instr->data;
      } else {
        LOG("No jump");
      }
      goto instr;

    case FH_INSTR_JUMP:
      LOG("\x1b[35mExec: jump -> 0x%08x\x1b[m", instr->data);
      if (instr->data == MAGICADDR_UNRESOLVED) {
        LOGE("Encountered unresolved jump!");
        goto end;
      }
      fh->execptr = instr->data;
      goto instr;

    case FH_INSTR_TO:
      TRY(ds_pop(fh, &val));
      w2 = fh_word_at(fh, instr->data);
      if (!w2) {
        LOGE("TO instr bad variable addr!");
        return FH_ERR_INTERNAL;
      }
      LOG("\x1b[35mExec: %d TO %s\x1b[m", val, w2->name);

      if (w2->flags & WORDFLAG_CONSTANT) {
        LOGE("Cannot assign to constant!");
        return FH_ERR_ILLEGAL_STORE;
      }

      w2->param = val;
      goto instr;

    case FH_INSTR_DO:
      LOG("\x1b[35mExec: do\x1b[m");
      TRY(ds_pop(fh, &index));
      TRY(ds_pop(fh, &limit)); // just make sure it exists
      TRY(fh_loop_nest(fh, index));
      TRY(rs_push(fh, limit));
      goto instr;

    case FH_INSTR_DO_QUESTION:
      LOG("\x1b[35mExec: ?do\x1b[m");
      if (instr->data == MAGICADDR_UNRESOLVED) {
        LOGE("Encountered unresolved jump!");
        goto end;
      }

      TRY(ds_pop(fh, &index));
      TRY(ds_pop(fh, &limit));
      if (index == limit) {
        // jump to end
        fh->execptr = instr->data;
      } else {
        TRY(fh_loop_nest(fh, index));
        TRY(rs_push(fh, limit));
      }
      goto instr;

    case FH_INSTR_LOOP_PLUS:
      TRY(ds_pop(fh, &val));
      // fall-through
    case FH_INSTR_LOOP:
      if (instr->kind == FH_INSTR_LOOP) {
        val = 1;
      }

      // R: index,limit
      TRY(rs_peek(fh, &limit));

      LOG("\x1b[35mExec: +LOOP\x1b[m, i=%d, step %d, limit %d", fh->loop_i, val, limit);

      const int32_t vi = (int32_t) val;
      const int32_t bdr = (int32_t) limit - (int32_t) 1;
      const int32_t i0 = (int32_t) fh->loop_i;
      fh->loop_i += val; // this can overflow
      const int32_t i1 = (int32_t) fh->loop_i;

      // TODO this can probably be optimized
      if (
          (vi > 0 && i0 <= bdr && i1 > bdr)
          || (vi > 0 && i0 > 0 && i1 < 0 && (bdr >= i0 || bdr <= i1))
          || (vi < 0 && i0 > bdr && i1 <= bdr)
          || (vi < 0 && i0 < 0 && i1 > 0 && (bdr <= i0 || bdr >= i1))
          ) {
        //LOGE("end of loop");
        // end of loop
        TRY(rs_pop(fh, &limit));
        TRY(fh_loop_unnest(fh));
      } else {
        //LOGE("continue loop");
        // continue the loop
        fh->execptr = instr->data;
      }
      goto instr;

    case FH_INSTR_LEAVE:
      LOG("\x1b[35mExec: leave\x1b[m");
      if (instr->data == MAGICADDR_UNRESOLVED) {
        LOGE("Encountered unresolved jump!");
        goto end;
      }
      TRY(rs_pop(fh, &limit));
      TRY(fh_loop_unnest(fh));
      fh->execptr = instr->data;
      goto instr;

    case FH_INSTR_OF:
      LOG("\x1b[35mExec: OF\x1b[m");
      if (instr->data == MAGICADDR_UNRESOLVED) {
        LOGE("Encountered unresolved OF!");
        goto end;
      }
      TRY(ds_pop(fh, &testval));
      TRY(ds_pop(fh, &val));

      LOG("Val %d, testval %d", val, testval);

      if (testval != val) {
        LOG("No match, go to ENDOF");
        TRY(ds_push(fh, val));
        fh->execptr = instr->data;
      }
      goto instr;

    case FH_INSTR_ENDCASE:
      LOG("\x1b[35mExec: ENDCASE\x1b[m");
      TRY(ds_pop(fh, &val)); // discard the tested value
      goto instr;

    case FH_INSTR_ALLOCSTR:
      strl = instr->data;
      LOG("\x1b[35mExec: alloc-str\x1b[m \"%.*s\"", strl, fh_str_at(fh, fh->execptr));
      TRY(ds_push(fh, fh->execptr)); // give pointer directly into the definition
      TRY(ds_push(fh, strl));
      fh->execptr += strl;
      goto instr;

    case FH_INSTR_ALLOCSTR_C:
      LOG("\x1b[35mExec: alloc-str-c\x1b[m \"%.*s\", %d", fh->heap[fh->execptr], fh_str_at(fh, fh->execptr + 1), fh->heap[fh->execptr]);
      TRY(ds_push(fh, fh->execptr));
      fh->execptr += instr->data;
      goto instr;

    case FH_INSTR_TYPESTR:
      strl = instr->data;
      LOG("\x1b[35mExec: type-str\x1b[m \"%.*s\"", strl, fh_str_at(fh, fh->execptr));
      FHPRINT("%.*s", (int) strl, fh_str_at(fh, fh->execptr));
      fh->execptr += strl;
      goto instr;

    case FH_INSTR_ABORTSTR:
      strl = instr->data;
      TRY(ds_pop(fh, &val));
      LOG("\x1b[35mExec: abort-str\x1b[m \"%.*s\"", strl, fh_str_at(fh, fh->execptr));
      if (val != 0) {
        FHPRINT("%.*s", (int) strl, fh_str_at(fh, fh->execptr));   
        LOG("ABORTing");     
        fh_abort(fh);
        goto end;
      }
      fh->execptr += strl;
      goto instr;

    case FH_INSTR_ENDWORD:
      LOG("\x1b[35mExec: word-end\x1b[m");
      TRY(rs_pop(fh, &fh->execptr));
      if (fh->execptr == MAGICADDR_EXEC_INTERACTIVE) {
        LOG("Done running compiled word");
        goto end;
      }
      goto instr;
      
    case FH_INSTR_ACTIONOF:
      LOG("\x1b[35mExec: actionof\x1b[m");
      w2 = fh_word_at(fh, instr->data);
      TRY(ds_push(fh, w2->param));
      goto instr;
      
    case FH_INSTR_ISDEFER:
      LOG("\x1b[35mExec: isdefer\x1b[m");
      w2 = fh_word_at(fh, instr->data);
      TRY(ds_pop(fh, &w2->param));
      goto instr;

    default:
      LOGE("Run handler not implemented for instr opcode %d", instr->kind);
      return FH_ERR_BAD_OPCODE;
  }

  end:
  fh->executing_compiled = 0;
  return FH_OK;
}


/** Initialize a runtime */
enum fh_error fh_init(struct fh_thread_s *fh)
{
  enum fh_error rv;

  /* Make sure we have a clean state */
  memset(fh, 0, sizeof(struct fh_thread_s));

  fh->dict_last = MAGICADDR_DICTFIRST;
  TRY(register_builtin_words(fh));

  fh->execptr = MAGICADDR_EXEC_INTERACTIVE;
  fh->base = 10;
  return FH_OK;
}

enum fh_error fh_handle_word(struct fh_thread_s *fh, uint32_t addr)
{
  enum fh_error rv;
  struct fh_word_s *w = fh_word_at(fh, addr);
  if (!w) { return FH_ERR_INTERNAL; }
  if (fh->state == FH_STATE_COMPILE && 0 == (w->flags & WORDFLAG_IMMEDIATE)) {
    LOG("\x1b[34m[%s] Compile word:\x1b[m %s", stateshort[fh->state], w->name);
    TRY(fh_put_instr(fh, FH_INSTR_WORD, addr));
  } else {
    /* interpret or immediate in compiled code */
//    enum fh_state oldstate = fh->state;
//    fh_setstate(fh, FH_STATE_INTERPRET, 0);
    LOG("\x1b[35m[%s] Run word:\x1b[m %s%s", stateshort[fh->state], w->name, (w->flags & WORDFLAG_IMMEDIATE) ? " 'imm" : "");
    TRY(w->handler(fh, w));
//    if (fh->state == FH_STATE_INTERPRET && fh->substate == FH_SUBSTATE_NONE) {
//      fh_setstate(fh, oldstate, 0);
//    }
  }
  return FH_OK;
}

enum fh_error fh_find_word(struct fh_thread_s *fh, const char *name, size_t wordlen, uint32_t *addr_out)
{
  if (name == NULL) {
    return FH_ERR_UNKNOWN_WORD;
  }
  if (wordlen == 0) {
    wordlen = strlen(name);
  }
  uint32_t addr = fh->dict_last;
  while (addr != MAGICADDR_DICTFIRST) {
    struct fh_word_s *w = fh_word_at(fh, addr);
    if (!w) {
      break;
    }
    if (EQ(name, w->name, wordlen) && 0 == (w->flags & WORDFLAG_HIDDEN)) { // skip hidden names
      if (addr_out) {
        *addr_out = addr;
      }
      return FH_OK;
    }
    addr = w->previous;
  }
  // no log message, this can be OK - e.g. parsing a number
  //LOG("fail to find word %.*s", wordlen, name);
  return FH_ERR_UNKNOWN_WORD;
}

enum fh_error fh_loop_nest(struct fh_thread_s *fh, uint32_t indexvalue)
{
  enum fh_error rv;
  LOG("Loop nest");
  TRY(rs_push(fh, fh->loop_j));
  fh->loop_j = fh->loop_i;
  fh->loop_i = indexvalue;
  return FH_OK;
}

enum fh_error fh_loop_unnest(struct fh_thread_s *fh)
{
  enum fh_error rv;
  LOG("Loop un-nest");
  fh->loop_i = fh->loop_j;
  TRY(rs_pop(fh, &fh->loop_j));
  return FH_OK;
}


/** Postpone a word */
enum fh_error fh_postpone_word(
    struct fh_thread_s *fh,
    const char *name,
    const size_t wordlen
)
{
  enum fh_error rv;
  uint32_t wadr;
  TRY(fh_find_word(fh, name, wordlen, &wadr));

  LOG("Postpone word");
  TRY(fh_put_instr(fh, FH_INSTR_POSTPONED_WORD, wadr));

  return FH_OK;
}