/*************************************************************************
 *									 *
 *	 YAP Prolog 							 *
 *									 *
 *	Yap Prolog was developed at NCCUP - Universidade do Porto	 *
 *									 *
 * Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997	 *
 *									 *
 **************************************************************************
 *									 *
 * File:		readline.c *
 * Last rev:	5/2/88							 *
 * mods: *
 * comments:	Input/Output C implemented predicates			 *
 *									 *
 *************************************************************************/
#ifdef SCCS
static char SccsId[] = "%W% %G%";
#endif

/** @file readline.c
 *
 *
 * This file includes the interface to the readline library, if installed in the
 *system.
 *
 */

#include "Yap.h"
#include "YapHeap.h"
#include "Yatom.h"
#include "yapio.h"
#include <stdlib.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#if HAVE_STDARG_H
#include <stdarg.h>
#endif
#ifdef _WIN32
#if HAVE_IO_H
/* Windows */
#include <io.h>
#endif
#if HAVE_SOCKET
#include <winsock2.h>
#endif
#include <windows.h>
#ifndef S_ISDIR
#define S_ISDIR(x) (((x)&_S_IFDIR) == _S_IFDIR)
#endif
#endif

#include "iopreds.h"

#if defined(HAVE_LIBREADLINE)

#include <readline/history.h>
#include <readline/readline.h>

static int ReadlineGetc(int);

static const char *history_file;

#define READLINE_OUT_BUF_MAX 256

typedef struct scan_atoms {
  Int pos;
  Atom atom;
} scan_atoms_t;

static char *atom_enumerate(const char *prefix, int state) {
  CACHE_REGS
  struct scan_atoms *index;
  Atom catom;
  Int i;

  if (!state) {
    index = (struct scan_atoms *)malloc(sizeof(struct scan_atoms));
    i = 0;
    catom = NIL;
  } else {
    CACHE_REGS
    index = LOCAL_search_atoms;
    catom = index->atom;
    i = index->pos;
  }

  while (catom != NIL || i < AtomHashTableSize) {
    //    if ( is_signalled() )		/* Notably allow windows version */
    //      PL_handle_signals();		/* to break out on ^C */
    AtomEntry *ap;

    if (catom == NIL) {
      /* move away from current hash table line */
      READ_LOCK(HashChain[i].AERWLock);
      catom = HashChain[i].Entry;
      READ_UNLOCK(HashChain[i].AERWLock);
      i++;
    } else {
      ap = RepAtom(catom);
      READ_LOCK(ap->ARWLock);
      if (strstr((char *)ap->StrOfAE, prefix) == (char *)ap->StrOfAE) {
        index->pos = i;
        index->atom = ap->NextOfAE;
        LOCAL_search_atoms = index;
        READ_UNLOCK(ap->ARWLock);
        return ap->StrOfAE;
      }
      catom = ap->NextOfAE;
      READ_UNLOCK(ap->ARWLock);
    }
  }
  LOCAL_search_atoms = NULL;
  free(index);
  return NULL;
}

static char *atom_generator(const char *prefix, int state) {
  char *s = atom_enumerate(prefix, state);

  if (s) {
    char *copy = malloc(1 + strlen(s));

    if (copy) /* else pretend no completion */
      strcpy(copy, s);
    s = copy;
  }

  return s;
}

typedef struct chain {
  struct chain *next;
  char data[2];
} chain_t;

static char *predicate_enumerate(const char *prefix, int state) {
  CACHE_REGS
  PredEntry *p;
  ModEntry m0, *mod;
  AtomEntry *ap;

  if (!state) {
    p = NULL;
    mod = &m0;
    m0.NextME = CurrentModules;
    if (mod->AtomOfME == AtomIDB)
      mod = mod->NextME;
  } else {
    Term cmod;
    p = LOCAL_SearchPreds;
    cmod = (p->ModuleOfPred != PROLOG_MODULE ? p->ModuleOfPred : TermProlog);
    mod = Yap_GetModuleEntry(cmod);
  }
  while (mod) {
    // move to next o;
    if (p)
      p = p->NextPredOfModule;
    while (p == NULL) {
      mod = mod->NextME;
      if (!mod) {
        // done
        LOCAL_SearchPreds = NULL;
        return NULL;
      }
      if (mod->AtomOfME == AtomIDB)
        mod = mod->NextME;
      p = mod->PredForME;
    }
    char *c = RepAtom(ap = NameOfPred(p))->StrOfAE;
    if (strlen(c) > strlen(prefix) && strstr(c, prefix) == c &&
        !(p->PredFlags & HiddenPredFlag)) {
      LOCAL_SearchPreds = p;
      arity_t ar = p->ArityOfPE;
      int l, r;
      if (Yap_IsPrefixOp(AbsAtom(ap), &l, &r) && ar == 1) {
        return c;
      }
      strncpy(LOCAL_FileNameBuf, c, YAP_FILENAME_MAX);
      strncat(LOCAL_FileNameBuf, "(", YAP_FILENAME_MAX);
      return LOCAL_FileNameBuf;
    }
  }
  LOCAL_SearchPreds = NULL;
  return NULL;
}

static char *predicate_generator(const char *prefix, int state) {
  char *s = predicate_enumerate(prefix, state);

  if (s) {
    char *copy = malloc(1 + strlen(s));

    if (copy) /* else pretend no completion */
      strcpy(copy, s);
    s = copy;
  }

  return s;
}

static char **prolog_completion(const char *text, int start, int end) {
  char **matches = NULL;

  if (start == 0 && isalpha(text[0])) {
    int i = 0;
    while (i < end) {
      if (isalnum(text[i]) || text[i] == '_')
        i++;
      else
        break;
    }
    if (i == end) {
      matches = rl_completion_matches((char *)text, predicate_generator);
    }
    return matches;
  } else if (start == 0) {
    int i = 0;
    const char *p;
    while (isblank(text[i++]) && i <= end)
      ;
    p = text + i;

    if ((strstr(p, "[") == p) || (strstr(p, "compile(") == p) ||
        (strstr(p, "consult(") == p) || (strstr(p, "load_files(") == p) ||
        (strstr(p, "reconsult(") == p) || (strstr(p, "use_module(") == p) ||
        (strstr(p, "cd(") == p))
      matches = rl_completion_matches((char *)text, /* for pre-4.2 */
                                      rl_filename_completion_function);
    return matches;
  }
  int i = end, ch = '\0';
  while (i > start) {
    ch = text[--i];
    if (ch == '\'')
      return rl_completion_matches((char *)text, /* for pre-4.2 */
                                   rl_filename_completion_function);
    if (isalnum(text[i]))
      continue;
    break;
  }
  if (islower(ch))
    return rl_completion_matches((char *)text, atom_generator);

  return NULL;
}

void Yap_ReadlineFlush(int sno) {
  if (GLOBAL_Stream[sno].status & Tty_Stream_f &&
      GLOBAL_Stream[sno].status & Output_Stream_f) {
    rl_redisplay();
  }
}

bool Yap_readline_clear_pending_input(StreamDesc *s) {  
#if HAVE_RL_CLEAR_PENDING_INPUT
  rl_clear_pending_input();
#endif
  if (s->u.irl.buf) {
    free((void *)s->u.irl.buf);
  }
  s->u.irl.ptr = s->u.irl.buf = NULL;
  return true;
}

bool Yap_ReadlineOps(StreamDesc *s) {
  if (s->status & Tty_Stream_f) {
    if (GLOBAL_Stream[0].status & (Input_Stream_f | Tty_Stream_f) &&
        is_same_tty(s->file, GLOBAL_Stream[0].file))
      s->stream_getc = ReadlineGetc;
    s->status |= Readline_Stream_f;
    return true;
  }
  return false;
}

bool Yap_InitReadline(Term enable) {
  // don't call readline within emacs
  if (Yap_embedded)
    return false;
  if (!(GLOBAL_Stream[StdInStream].status & Tty_Stream_f) ||
      getenv("INSIDE_EMACS") || enable != TermTrue) {
    if (GLOBAL_Flags)
      setBooleanGlobalPrologFlag(READLINE_FLAG, false);
    return false;
  }
  GLOBAL_Stream[StdInStream].u.irl.buf = NULL;
  GLOBAL_Stream[StdInStream].u.irl.ptr = NULL;
  GLOBAL_Stream[StdInStream].status |= Readline_Stream_f;
#if _WIN32
  rl_instream = stdin;
#endif
  // rl_outstream = stderr;
  using_history();
  const char *s = Yap_AbsoluteFile("~/.YAP.history", NULL, true);
  history_file = s;
  if (read_history(s) != 0) {
    FILE *f = fopen(s, "a");
    if (f) {
      fclose(f);
    }
  }
  rl_readline_name = "YAP Prolog";
  rl_attempted_completion_function = prolog_completion;
  // rl_prep_terminal(1);
  if (GLOBAL_Flags)
    setBooleanGlobalPrologFlag(READLINE_FLAG, true);
  return Yap_ReadlineOps(GLOBAL_Stream + StdInStream);
}

#if !HAVE_RL_SET_SIGNALS
#define rl_clear_signals()
#define rl_set_signals()
#endif

static bool getLine(int inp) {
  CACHE_REGS
  rl_instream = GLOBAL_Stream[inp].file;
  const unsigned char *myrl_line = NULL;
  StreamDesc *s = GLOBAL_Stream + inp;

  /* window of vulnerability opened */
  LOCAL_PrologMode |= ConsoleGetcMode;
  if (Yap_DoPrompt(s)) { // no output so far
    rl_set_signals();
    myrl_line = (unsigned char *)readline(LOCAL_Prompt);
    rl_clear_signals();
  } else {
    rl_set_signals();
    myrl_line = (unsigned char *)readline(NULL);
    rl_clear_signals();
  }
  /* Do it the gnu way */
  LOCAL_PrologMode &= ~ConsoleGetcMode;
#if HAVE_RL_PENDING_SIGNAL
  if (rl_pending_signal()) {
    LOCAL_PrologMode |= InterruptMode;
  }
#endif
  if (LOCAL_PrologMode & InterruptMode) {
    Yap_HandleSIGINT();
  } else {
    LOCAL_newline = true;
  }
  strncpy(LOCAL_Prompt, RepAtom(LOCAL_AtPrompt)->StrOfAE, MAX_PROMPT);
  /* window of vulnerability closed */
  if (myrl_line == NULL)
    return false;
  if (myrl_line[0] != '\0' && myrl_line[1] != '\0') {
    add_history((char *)myrl_line);
    write_history(history_file);
    fflush(NULL);
  }
  s->u.irl.ptr = s->u.irl.buf = myrl_line;
  myrl_line = NULL;
  return true;
}

/**
  @brief reading from the console is complicated because we need to
  know whether to prompt and so on...

  EOF must be handled by resetting the file.
*/
static int ReadlineGetc(int sno) {
  StreamDesc *s = &GLOBAL_Stream[sno];
  int ch;
  bool fetch = (s->u.irl.buf == NULL);

  if (!fetch || getLine(sno)) {
    const unsigned char *ttyptr = s->u.irl.ptr++, *myrl_line = s->u.irl.buf;
    ch = *ttyptr;
    if (ch == '\0') {
      ch = '\n';
      free((void *)myrl_line);
      s->u.irl.ptr = s->u.irl.buf = NULL;
    }
  } else {
    return EOF;
  }
  return console_post_process_read_char(ch, s);
}

/**
  @brief  Yap_ReadlinePeekChar peeks the next char from the
  readline buffer, but does not actually grab it.

  The idea is to take advantage of the buffering. Special care must be taken
  with EOF, though.

*/
Int Yap_ReadlinePeekChar(int sno) {
  StreamDesc *s = &GLOBAL_Stream[sno];
  int ch;

  if (s->u.irl.buf) {
    const unsigned char *ttyptr = s->u.irl.ptr;
    ch = *ttyptr;
    if (ch == '\0') {
      ch = '\n';
    }
    return ch;
  }
  if (getLine(sno)) {
    CACHE_REGS
    ch = s->u.irl.ptr[0];
    if (ch == '\0') {
      ch = '\n';
    }
    if (ch == '\n') {
      LOCAL_newline = true;
    } else {
      LOCAL_newline = false;
    }
  } else {
    return EOF;
  }
  return ch;
}

int Yap_ReadlineForSIGINT(void) {
  CACHE_REGS
  int ch;
  StreamDesc *s = &GLOBAL_Stream[StdInStream];
  const unsigned char *myrl_line = s->u.irl.buf;
  if ((LOCAL_PrologMode & ConsoleGetcMode) && myrl_line != NULL) {
    ch = myrl_line[0];
    free((void *)myrl_line);
    myrl_line = NULL;
    fflush(NULL);
    return ch;
  } else {
    myrl_line = (const unsigned char *)readline("Action (h for help): ");
    if (!myrl_line) {
      ch = EOF;
      return ch;
    } else {
      ch = myrl_line[0];
      free((void *)myrl_line);
      myrl_line = NULL;
      fflush(NULL);
      return ch;
    }
  }
}

static Int has_readline(USES_REGS1) {
#if USE_READLINE
  if (!Yap_embedded) {
    return true;
  }
  return false;
#else
  return false;
#endif
}

void Yap_InitReadlinePreds(void) {
  Yap_InitCPred("$has_readline", 0, has_readline,
                SafePredFlag | HiddenPredFlag);
}

#else
bool Yap_InitReadline(Term enable) {
  return enable == TermTrue && !getenv("INSIDE_EMACS");
}

void Yap_InitReadlinePreds(void) {}
#endif

void Yap_CloseReadline(void) {
#if USE_READLINE
  write_history(history_file);
  history_truncate_file(history_file, 300);
#endif
}