#include <string.h>
#include <errno.h>
#include <ctype.h>

#include "forth.h"
#include "fh_runtime.h"
#include "fh_builtins.h"
#include "fh_stack.h"
#include "fh_mem.h"
#include "fh_globals.h"
#include "fh_print.h"

struct fh_global_s fh_globals = {};

/** Error names */
static const char *errornames[] = {
    [FH_OK] = "OK",
    [FH_ERR_CS_OVERFLOW] = "CS_OVERFLOW",
    [FH_ERR_DS_OVERFLOW] = "DS_OVERFLOW",
    [FH_ERR_RS_OVERFLOW] = "RS_OVERFLOW",
    [FH_ERR_CS_UNDERFLOW] = "CS_UNDERFLOW",
    [FH_ERR_DS_UNDERFLOW] = "DS_UNDERFLOW",
    [FH_ERR_RS_UNDERFLOW] = "RS_UNDERFLOW",
    [FH_ERR_HEAP_FULL] = "HEAP_FULL",
    [FH_ERR_DICT_FULL] = "DICT_FULL",
    [FH_ERR_COMPILE_FULL] = "COMPILE_FULL",
    [FH_ERR_NAME_TOO_LONG] = "NAME_TOO_LONG",
    [FH_ERR_INVALID_STATE] = "INVALID_STATE",
    [FH_ERR_INTERNAL] = "INTERNAL",
    [FH_ERR_UNKNOWN_WORD] = "UNKNOWN_WORD",
};

/** Get error name from code, returns Unknown if not defined */
const char *fherr_name(enum fh_error e)
{
  if (e >= FH_ERR_MAX) {
    return "Unknown";
  }
  return errornames[e];
}

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


/** Sub-state names */
static const char *substatenames[] = {
    [FH_SUBSTATE_NONE] = "NONE",
    [FH_SUBSTATE_COLONNAME] = "COLONNAME",
    [FH_SUBSTATE_SQUOTE] = "SQUOTE",
    [FH_SUBSTATE_DOTQUOTE] = "DOTQUOTE",
    [FH_SUBSTATE_PARENCOMMENT] = "PARENCOMMENT",
    [FH_SUBSTATE_LINECOMMENT] = "LINECOMMENT",
};

/** Add a word to the dictionary. */
enum fh_error fh_add_word(const struct fh_word_s *w, struct fh_thread_s *fh)
{
  if (fh->dict_top == DICT_SIZE) {
    return FH_ERR_DICT_FULL;
  }
  memcpy(&fh->dict[fh->dict_top++], w, sizeof(struct fh_word_s));
  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);
}

enum fh_error w_user_word(struct fh_thread_s *fh)
{
  enum fh_error rv;
  const struct fh_word_s *w;
  const struct fh_word_s *w2;
  uint32_t wn;

  call:
  w = fh->exec_word;
  if (!w) { return FH_ERR_INTERNAL; }

  LOG("Run user word: %s", w->name);

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

  instr:;
  // make sure it's aligned
  fh->execptr = WORDALIGNED(fh->execptr);
  const struct fh_instruction_s *instr = (const struct fh_instruction_s *) &fh->compile[fh->execptr];
  fh->execptr += sizeof(struct fh_instruction_s);

  uint32_t strl;
  uint32_t addr = 0;
  switch (instr->kind) {
    case FH_INSTR_NUMBER:
      TRY(ds_push(fh, instr->data));
      goto instr;

    case FH_INSTR_WORD:
      wn = instr->data;
      switch (wn) {
        /* special case for strings stored in compile memory */
        case CPLWORD_ALLOCSTR:
        case CPLWORD_TYPESTR:
          strl = *((uint32_t *) &fh->compile[fh->execptr]);
          LOG("strl %d", strl);
          fh->execptr += 4; // advance past the length
          if (wn == CPLWORD_ALLOCSTR) {
            TRY(fh_heap_reserve(fh, strl, &addr));
            fh_heap_copy_from_compile(fh, addr, fh->execptr, strl);
            LOG("Exec: alloc-str \"%.*s\"", strl, &fh->heap[addr]);
            TRY(ds_push(fh, addr));
            TRY(ds_push(fh, strl));
            fh->execptr += strl;
          } else {
            FHPRINT("%.*s", (int) strl, &fh->compile[fh->execptr]);
            LOG("Exec: type-str \"%.*s\"", strl, &fh->compile[fh->execptr]);
          }
          goto instr;

        case CPLWORD_ENDWORD:
          LOG("Exec: word-end (RETURN)");
          TRY(rs_pop(fh, &fh->execptr));
          if (fh->execptr == MAGICADDR_INTERACTIVE) {
            goto end;
          }
          goto instr;

        default:
          w2 = &fh->dict[instr->data];
          if (w2->builtin) {
            LOG("Exec: builtin-word %s", w2->name);
            w2->handler(fh);
            goto instr;
          } else {
            LOG("Exec: user-word %s (CALL)", w2->name);
            fh->exec_word = &fh->dict[instr->data];
            goto call;
          }
      }
  }

  end:
  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));

  TRY(register_builtin_words(fh));

  fh->execptr = MAGICADDR_INTERACTIVE;
  return FH_OK;
}

/** Process a quoted string read from input */
static enum fh_error fh_handle_quoted_string(
    struct fh_thread_s *fh,
    const char *start,
    size_t len
)
{
  enum fh_error rv;
  uint32_t addr = 0;
  struct fh_instruction_s instr;

  if (fh->state == FH_STATE_INTERPRET) {
    switch (fh->substate) {
      case FH_SUBSTATE_SQUOTE:
        TRY(fh_heap_put(fh, start, len));
        TRY(ds_push(fh, addr));
        TRY(ds_push(fh, len));
        break;
      case FH_SUBSTATE_DOTQUOTE:
        FHPRINT("%.*s", (int) len, start);
        break;

      default:
        LOGE("Bad substate in interpret mode: %s", substatenames[fh->substate]);
    }
  } else {
    LOG("Compile a string");
    /* compile */
    if (fh->substate == FH_SUBSTATE_SQUOTE) {
      instr_init(&instr, FH_INSTR_WORD, CPLWORD_ALLOCSTR);
    } else {
      instr_init(&instr, FH_INSTR_WORD, CPLWORD_TYPESTR);
    }
    uint32_t len32 = len;
    /* string is encoded as a special compiler command, the size,
     * and then the string, all 4-byte aligned. */
    TRY(fh_compile_put(fh, &instr, INSTR_SIZE));

    TRY(fh_compile_reserve(fh, len + 4, &addr));
    fh_compile_write(fh, addr, &len32, 4);
    fh_compile_write(fh, addr + 4, start, len);
  }
  return FH_OK;
}

/** Process a word read from input */
static enum fh_error fh_handle_word(
    struct fh_thread_s *fh,
    const char *start,
    size_t len
)
{
  if (len >= MAX_NAME_LEN) {
    return FH_ERR_NAME_TOO_LONG;
  }

  /* First, try if it's a known word */
  // TODO we could use binary search if the dict was ordered
  struct fh_word_s *w = &fh->dict[0];
  struct fh_instruction_s instr;
  uint32_t cnt = 0;
  enum fh_error rv;
  while (w->handler) {
    if (0 == strncasecmp(start, w->name, len) && w->name[len] == 0) {
      // word found!
      if (fh->state == FH_STATE_COMPILE && !w->immediate) {
        LOG("Compile word call: %s", w->name);
        instr_init(&instr, FH_INSTR_WORD, cnt);
        TRY(fh_compile_put(fh, &instr, INSTR_SIZE));
      } else {
        /* interpret */
        LOG("Interpret word: %s", w->name);
        fh->exec_word = w;
        TRY(w->handler(fh));
      }
      return FH_OK;
    }
    w++;
    cnt++;
  }

  /* word not found, try parsing as number */
  errno = 0;
  char *endptr;
  long v = strtol(start, &endptr, 0);
  if (errno != 0 || endptr == start) {
    LOGE("Unknown word and fail to parse as number: %.*s", (int) len, start);
    return FH_ERR_UNKNOWN_WORD;
  }

  if (fh->state == FH_STATE_COMPILE) {
    LOG("Compile number: %ld", v);
    instr_init(&instr, FH_INSTR_NUMBER, (uint32_t) v);
    TRY(fh_compile_put(fh, &instr, INSTR_SIZE));
  } else {
    /* interpret */
    LOG("Interpret number: %ld", v);
    TRY(ds_push(fh, (uint32_t) v));
  }

  return FH_OK;
}

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

/** Process a line read from input */
enum fh_error fh_process_line(struct fh_thread_s *fh, const char *linebuf)
{
  enum fh_error rv;
  const char *rp = linebuf;
  char c;

  if (!fh_globals.interactive) {
    LOGI("%s", linebuf);
  }

  while (0 != (c = *rp) && fh->state != FH_STATE_SHUTDOWN) {
    /* end on newline */
    if (isnl(c)) {
      goto done;
    }
    /* skip whitespace */
    if (isspace(c)) {
      rp++;
      continue;
    }

    char *end;
    size_t length;
    switch (fh->substate) {
      case FH_SUBSTATE_NONE:
      case FH_SUBSTATE_COLONNAME:
        /* try to read a word */
        end = strchr(rp, ' ');
        if (end) {
          length = end - rp; /* exclude the space */
        } else {
          length = strlen(rp);
        }

        if (fh->substate == FH_SUBSTATE_NONE) {
          /* eval a word */
          LOG("Handle \"%.*s\"", (int) length, rp);
          TRY(fh_handle_word(fh, rp, length));
        } else {
          /* new word's name is found */
          LOG("New word name = \"%.*s\"", (int) length, rp);
          strncpy(fh->dict[fh->dict_top].name, rp, length);
          fh_setsubstate(fh, FH_SUBSTATE_NONE);
        }

        if (end) {
          rp = end + 1;
        } else {
          goto done;
        }
        break;

      case FH_SUBSTATE_SQUOTE:
      case FH_SUBSTATE_DOTQUOTE:
        end = strchr(rp, '"');
        if (end) {
          length = end - rp;
          LOG("Quoted string: \"%.*s\"", (int) length, rp);
          TRY(fh_handle_quoted_string(fh, rp, length));
          fh_setsubstate(fh, FH_SUBSTATE_NONE);
          rp = end + 1;
        } else {
          /* no end. this is weird. */
          LOGE("Unterminated quoted string!");
          goto done;
        }
        break;

      case FH_SUBSTATE_PARENCOMMENT:
        end = strchr(rp, ')');
        if (end) {
          LOG("Discard inline comment");
          fh_setsubstate(fh, FH_SUBSTATE_NONE);
          rp = end + 1;
        } else {
          /* no end, discard all */
          LOGE("Unterminated parenthesis comment");
          goto done;
        }
        break;

      case FH_SUBSTATE_LINECOMMENT:
        LOG("Discard line comment");
        goto done; // just discard the rest

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