/* string.c: Glulxe string and text functions.
    Designed by Andrew Plotkin <erkyrath@eblong.com>
    http://eblong.com/zarf/glulx/index.html
*/

#include "glk.h"
#include "glulxe.h"

static glui32 iosys_mode;
static glui32 iosys_rock;
/* These constants are defined in the Glulx spec. */
#define iosys_None (0)
#define iosys_Filter (1)
#define iosys_Glk (2)

#define CACHEBITS (4)
#define CACHESIZE (1<<CACHEBITS) 
#define CACHEMASK (15)

typedef struct cacheblock_struct {
  int depth; /* 1 to 4 */
  int type;
  union {
    struct cacheblock_struct *branches;
    unsigned char ch;
    glui32 uch;
    glui32 addr;
  } u;
} cacheblock_t;

/* The current string-decoding tables, broken out into a fast and
   easy-to-use form. */
static int tablecache_valid = FALSE;
static cacheblock_t tablecache;

static void stream_setup_unichar(void);

static void nopio_char_han(unsigned char ch);
static void filio_char_han(unsigned char ch);
static void nopio_unichar_han(glui32 ch);
static void filio_unichar_han(glui32 ch);
static void glkio_unichar_nouni_han(glui32 val);
static void (*glkio_unichar_han_ptr)(glui32 val) = NULL;

static void dropcache(cacheblock_t *cablist);
static void buildcache(cacheblock_t *cablist, glui32 nodeaddr, int depth,
  int mask);
static void dumpcache(cacheblock_t *cablist, int count, int indent);

void stream_get_iosys(glui32 *mode, glui32 *rock)
{
  *mode = iosys_mode;
  *rock = iosys_rock;
}

static void stream_setup_unichar()
{
#ifdef GLK_MODULE_UNICODE

  if (glk_gestalt(gestalt_Unicode, 0))
    glkio_unichar_han_ptr = glk_put_char_uni;
  else
    glkio_unichar_han_ptr = glkio_unichar_nouni_han;

#else /* GLK_MODULE_UNICODE */

  glkio_unichar_han_ptr = glkio_unichar_nouni_han;

#endif /* GLK_MODULE_UNICODE */
}

void stream_set_iosys(glui32 mode, glui32 rock)
{
  switch (mode) {
  default:
    mode = 0;
    /* ...and fall through to next case (no-op I/O). */
  case iosys_None:
    rock = 0;
    stream_char_handler = nopio_char_han;
    stream_unichar_handler = nopio_unichar_han;
    break;
  case iosys_Filter:
    stream_char_handler = filio_char_han;
    stream_unichar_handler = filio_unichar_han;
    break;
  case iosys_Glk:
    if (!glkio_unichar_han_ptr)
      stream_setup_unichar();
    rock = 0;
    stream_char_handler = glk_put_char;
    stream_unichar_handler = glkio_unichar_han_ptr;
    break;
  }

  iosys_mode = mode;
  iosys_rock = rock;
}

static void nopio_char_han(unsigned char ch)
{
}

static void nopio_unichar_han(glui32 ch)
{
}

static void filio_char_han(unsigned char ch)
{
  glui32 val = ch;
  push_callstub(0, 0);
  enter_function(iosys_rock, 1, &val);
}

static void filio_unichar_han(glui32 val)
{
  push_callstub(0, 0);
  enter_function(iosys_rock, 1, &val);
}

static void glkio_unichar_nouni_han(glui32 val)
{
  /* Only used if the Glk library has no Unicode functions */
  if (val > 0xFF)
    val = '?';
  glk_put_char(val);
}

/* stream_num():
   Write a signed integer to the current output stream.
*/
void stream_num(glsi32 val, int inmiddle, int charnum)
{
  int ix = 0;
  int res, jx;
  char buf[16];
  glui32 ival;

  if (val == 0) {
    buf[ix] = '0';
    ix++;
  }
  else {
    if (val < 0) 
      ival = -val;
    else 
      ival = val;

    while (ival != 0) {
      buf[ix] = (ival % 10) + '0';
      ix++;
      ival /= 10;
    }

    if (val < 0) {
      buf[ix] = '-';
      ix++;
    }
  }

  switch (iosys_mode) {

  case iosys_Glk:
    ix -= charnum;
    while (ix > 0) {
      ix--;
      glk_put_char(buf[ix]);
    }
    break;

  case iosys_Filter:
    if (!inmiddle) {
      push_callstub(0x11, 0);
      inmiddle = TRUE;
    }
    if (charnum < ix) {
      ival = buf[(ix-1)-charnum] & 0xFF;
      pc = val;
      push_callstub(0x12, charnum+1);
      enter_function(iosys_rock, 1, &ival);
      return;
    }
    break;

  default:
    break;

  }

  if (inmiddle) {
    res = pop_callstub_string(&jx);
    if (res) 
      fatal_error("String-on-string call stub while printing number.");
  }
}

/* stream_string():
   Write a Glulx string object to the current output stream.
   inmiddle is zero if we are beginning a new string, or
   nonzero if restarting one (E0/E1/E2, as appropriate for
   the string type).
*/
void stream_string(glui32 addr, int inmiddle, int bitnum)
{
  int ch;
  int type;
  int alldone = FALSE;
  int substring = (inmiddle != 0);
  glui32 ival;

  if (!addr)
    fatal_error("Called stream_string with null address.");
  
  while (!alldone) {

    if (inmiddle == 0) {
      type = Mem1(addr);
      if (type == 0xE2)
        addr+=4;
      else
        addr++;
      bitnum = 0;
    }
    else {
      type = inmiddle;
    }

    if (type == 0xE1) {
      if (tablecache_valid) {
        int bits, numbits;
        int readahead;
        glui32 tmpaddr;
        cacheblock_t *cablist;
        int done = 0;

        /* bitnum is already set right */
        bits = Mem1(addr); 
        if (bitnum)
          bits >>= bitnum;
        numbits = (8 - bitnum);
        readahead = FALSE;

        if (tablecache.type != 0) {
          /* This is a bit of a cheat. If the top-level block is not
             a branch, then it must be a string-terminator -- otherwise
             the string would be an infinite repetition of that block.
             We check for this case and bail immediately. */
          done = 1;
        }

        cablist = tablecache.u.branches;
        while (!done) {
          cacheblock_t *cab;

          if (numbits < CACHEBITS) {
            /* readahead is certainly false */
            int newbyte = Mem1(addr+1);
            bits |= (newbyte << numbits);
            numbits += 8;
            readahead = TRUE;
          }

          cab = &(cablist[bits & CACHEMASK]);
          numbits -= cab->depth;
          bits >>= cab->depth;
          bitnum += cab->depth;
          if (bitnum >= 8) {
            addr += 1;
            bitnum -= 8;
            if (readahead) {
              readahead = FALSE;
            }
            else {
              int newbyte = Mem1(addr);
              bits |= (newbyte << numbits);
              numbits += 8;
            }
          }

          switch (cab->type) {
          case 0x00: /* non-leaf node */
            cablist = cab->u.branches;
            break;
          case 0x01: /* string terminator */
            done = 1;
            break;
          case 0x02: /* single character */
            switch (iosys_mode) {
            case iosys_Glk:
              glk_put_char(cab->u.ch);
              break;
            case iosys_Filter: 
              ival = cab->u.ch & 0xFF;
              if (!substring) {
                push_callstub(0x11, 0);
                substring = TRUE;
              }
              pc = addr;
              push_callstub(0x10, bitnum);
              enter_function(iosys_rock, 1, &ival);
              return;
            }
            cablist = tablecache.u.branches;
            break;
          case 0x04: /* single Unicode character */
            switch (iosys_mode) {
            case iosys_Glk:
              glkio_unichar_han_ptr(cab->u.uch);
              break;
            case iosys_Filter: 
              ival = cab->u.uch;
              if (!substring) {
                push_callstub(0x11, 0);
                substring = TRUE;
              }
              pc = addr;
              push_callstub(0x10, bitnum);
              enter_function(iosys_rock, 1, &ival);
              return;
            }
            cablist = tablecache.u.branches;
            break;
          case 0x03: /* C string */
            switch (iosys_mode) {
            case iosys_Glk:
              for (tmpaddr=cab->u.addr; (ch=Mem1(tmpaddr)) != '\0'; tmpaddr++) 
                glk_put_char(ch);
              cablist = tablecache.u.branches; 
              break;
            case iosys_Filter:
              if (!substring) {
                push_callstub(0x11, 0);
                substring = TRUE;
              }
              pc = addr;
              push_callstub(0x10, bitnum);
              inmiddle = 0xE0;
              addr = cab->u.addr;
              done = 2;
              break;
            default:
              cablist = tablecache.u.branches; 
              break;
            }
            break;
          case 0x05: /* C Unicode string */
            switch (iosys_mode) {
            case iosys_Glk:
              for (tmpaddr=cab->u.addr; (ival=Mem4(tmpaddr)) != 0; tmpaddr+=4) 
                glkio_unichar_han_ptr(ival);
              cablist = tablecache.u.branches; 
              break;
            case iosys_Filter:
              if (!substring) {
                push_callstub(0x11, 0);
                substring = TRUE;
              }
              pc = addr;
              push_callstub(0x10, bitnum);
              inmiddle = 0xE2;
              addr = cab->u.addr;
              done = 2;
              break;
            default:
              cablist = tablecache.u.branches; 
              break;
            }
            break;
          case 0x08:
          case 0x09:
          case 0x0A:
          case 0x0B: 
            {
              glui32 oaddr;
              int otype;
              oaddr = cab->u.addr;
              if (cab->type >= 0x09)
                oaddr = Mem4(oaddr);
              if (cab->type == 0x0B)
                oaddr = Mem4(oaddr);
              otype = Mem1(oaddr);
              if (!substring) {
                push_callstub(0x11, 0);
                substring = TRUE;
              }
              if (otype >= 0xE0 && otype <= 0xFF) {
                pc = addr;
                push_callstub(0x10, bitnum);
                inmiddle = 0;
                addr = oaddr;
                done = 2;
              }
              else if (otype >= 0xC0 && otype <= 0xDF) {
                glui32 argc;
                glui32 *argv;
                if (cab->type == 0x0A || cab->type == 0x0B) {
                  argc = Mem4(cab->u.addr+4);
                  argv = pop_arguments(argc, cab->u.addr+8);
                }
                else {
                  argc = 0;
                  argv = NULL;
                }
                pc = addr;
                push_callstub(0x10, bitnum);
                enter_function(oaddr, argc, argv);
                return;
              }
              else {
                fatal_error("Unknown object while decoding string indirect reference.");
              }
            }
            break;
          default:
            fatal_error("Unknown entity in string decoding (cached).");
            break;
          }
        }
        if (done > 1) {
          continue; /* restart the top-level loop */
        }
      }
      else { /* tablecache not valid */
        glui32 node;
        int byte;
        int nodetype;
        int done = 0;

        if (!stringtable)
          fatal_error("Attempted to print a compressed string with no table set.");
        /* bitnum is already set right */
        byte = Mem1(addr); 
        if (bitnum)
          byte >>= bitnum;
        node = Mem4(stringtable+8);
        while (!done) {
          nodetype = Mem1(node);
          node++;
          switch (nodetype) {
          case 0x00: /* non-leaf node */
            if (byte & 1) 
              node = Mem4(node+4);
            else
              node = Mem4(node+0);
            if (bitnum == 7) {
              bitnum = 0;
              addr++;
              byte = Mem1(addr);
            }
            else {
              bitnum++;
              byte >>= 1;
            }
            break;
          case 0x01: /* string terminator */
            done = 1;
            break;
          case 0x02: /* single character */
            ch = Mem1(node);
            switch (iosys_mode) {
            case iosys_Glk:
              glk_put_char(ch);
              break;
            case iosys_Filter: 
              ival = ch & 0xFF;
              if (!substring) {
                push_callstub(0x11, 0);
                substring = TRUE;
              }
              pc = addr;
              push_callstub(0x10, bitnum);
              enter_function(iosys_rock, 1, &ival);
              return;
            }
            node = Mem4(stringtable+8);
            break;
          case 0x04: /* single Unicode character */
            ival = Mem4(node);
            switch (iosys_mode) {
            case iosys_Glk:
              glkio_unichar_han_ptr(ival);
              break;
            case iosys_Filter: 
              if (!substring) {
                push_callstub(0x11, 0);
                substring = TRUE;
              }
              pc = addr;
              push_callstub(0x10, bitnum);
              enter_function(iosys_rock, 1, &ival);
              return;
            }
            node = Mem4(stringtable+8);
            break;
          case 0x03: /* C string */
            switch (iosys_mode) {
            case iosys_Glk:
              for (; (ch=Mem1(node)) != '\0'; node++) 
                glk_put_char(ch);
              node = Mem4(stringtable+8);
              break;
            case iosys_Filter:
              if (!substring) {
                push_callstub(0x11, 0);
                substring = TRUE;
              }
              pc = addr;
              push_callstub(0x10, bitnum);
              inmiddle = 0xE0;
              addr = node;
              done = 2;
              break;
            default:
              node = Mem4(stringtable+8);
              break;
            }
            break;
          case 0x05: /* C Unicode string */
            switch (iosys_mode) {
            case iosys_Glk:
              for (; (ival=Mem4(node)) != 0; node+=4) 
                glkio_unichar_han_ptr(ival);
              node = Mem4(stringtable+8);
              break;
            case iosys_Filter:
              if (!substring) {
                push_callstub(0x11, 0);
                substring = TRUE;
              }
              pc = addr;
              push_callstub(0x10, bitnum);
              inmiddle = 0xE2;
              addr = node;
              done = 2;
              break;
            default:
              node = Mem4(stringtable+8);
              break;
            }
            break;
          case 0x08:
          case 0x09:
          case 0x0A:
          case 0x0B: 
            {
              glui32 oaddr;
              int otype;
              oaddr = Mem4(node);
              if (nodetype == 0x09 || nodetype == 0x0B)
                oaddr = Mem4(oaddr);
              otype = Mem1(oaddr);
              if (!substring) {
                push_callstub(0x11, 0);
                substring = TRUE;
              }
              if (otype >= 0xE0 && otype <= 0xFF) {
                pc = addr;
                push_callstub(0x10, bitnum);
                inmiddle = 0;
                addr = oaddr;
                done = 2;
              }
              else if (otype >= 0xC0 && otype <= 0xDF) {
                glui32 argc;
                glui32 *argv;
                if (nodetype == 0x0A || nodetype == 0x0B) {
                  argc = Mem4(node+4);
                  argv = pop_arguments(argc, node+8);
                }
                else {
                  argc = 0;
                  argv = NULL;
                }
                pc = addr;
                push_callstub(0x10, bitnum);
                enter_function(oaddr, argc, argv);
                return;
              }
              else {
                fatal_error("Unknown object while decoding string indirect reference.");
              }
            }
            break;
          default:
            fatal_error("Unknown entity in string decoding.");
            break;
          }
        }
        if (done > 1) {
          continue; /* restart the top-level loop */
        }
      }
    }
    else if (type == 0xE0) {
      switch (iosys_mode) {
      case iosys_Glk:
        while (1) {
          ch = Mem1(addr);
          addr++;
          if (ch == '\0')
            break;
          glk_put_char(ch);
        }
        break;
      case iosys_Filter:
        if (!substring) {
          push_callstub(0x11, 0);
          substring = TRUE;
        }
        ch = Mem1(addr);
        addr++;
        if (ch != '\0') {
          ival = ch & 0xFF;
          pc = addr;
          push_callstub(0x13, 0);
          enter_function(iosys_rock, 1, &ival);
          return;
        }
        break;
      }
    }
    else if (type == 0xE2) {
      switch (iosys_mode) {
      case iosys_Glk:
        while (1) {
          ival = Mem4(addr);
          addr+=4;
          if (ival == 0)
            break;
          glkio_unichar_han_ptr(ival);
        }
        break;
      case iosys_Filter:
        if (!substring) {
          push_callstub(0x11, 0);
          substring = TRUE;
        }
        ival = Mem4(addr);
        addr+=4;
        if (ival != 0) {
          pc = addr;
          push_callstub(0x14, 0);
          enter_function(iosys_rock, 1, &ival);
          return;
        }
        break;
      }
    }
    else if (type >= 0xE0 && type <= 0xFF) {
      fatal_error("Attempt to print unknown type of string.");
    }
    else {
      fatal_error("Attempt to print non-string.");
    }

    if (!substring) {
      /* Just get straight out. */
      alldone = TRUE;
    }
    else {
      /* Pop a stub and see what's to be done. */
      addr = pop_callstub_string(&bitnum);
      if (addr == 0) {
        alldone = TRUE;
      }
      else {
        inmiddle = 0xE1;
      }
    }
  }
}

/* stream_get_table():
   Get the current table address. 
*/
glui32 stream_get_table()
{
  return stringtable;
}

/* stream_set_table():
   Set the current table address, and rebuild decoding cache. 
*/
void stream_set_table(glui32 addr)
{
  if (stringtable == addr)
    return;

  /* Drop cache. */
  if (tablecache_valid) {
    if (tablecache.type == 0)
      dropcache(tablecache.u.branches);
    tablecache.u.branches = NULL;
    tablecache_valid = FALSE;
  }

  stringtable = addr;

  if (stringtable) {
    /* Build cache. We can only do this if the table is entirely in ROM. */
    glui32 tablelen = Mem4(stringtable);
    glui32 rootaddr = Mem4(stringtable+8);
    int cache_stringtable = (stringtable+tablelen <= ramstart);
    /* cache_stringtable = TRUE; ...for testing only */
    /* cache_stringtable = FALSE; ...for testing only */
    if (cache_stringtable) {
      buildcache(&tablecache, rootaddr, CACHEBITS, 0);
      /* dumpcache(&tablecache, 1, 0); */
      tablecache_valid = TRUE;
    }
  }
}

static void buildcache(cacheblock_t *cablist, glui32 nodeaddr, int depth,
  int mask)
{
  int ix, type;

  type = Mem1(nodeaddr);

  if (type == 0 && depth == CACHEBITS) {
    cacheblock_t *list, *cab;
    list = (cacheblock_t *)glulx_malloc(sizeof(cacheblock_t) * CACHESIZE);
    buildcache(list, nodeaddr, 0, 0);
    cab = &(cablist[mask]);
    cab->type = 0;
    cab->depth = CACHEBITS;
    cab->u.branches = list;
    return;
  }

  if (type == 0) {
    glui32 leftaddr  = Mem4(nodeaddr+1);
    glui32 rightaddr = Mem4(nodeaddr+5);
    buildcache(cablist, leftaddr, depth+1, mask);
    buildcache(cablist, rightaddr, depth+1, (mask | (1 << depth)));
    return;
  }

  /* Leaf node. */
  nodeaddr++;
  for (ix = mask; ix < CACHESIZE; ix += (1 << depth)) {
    cacheblock_t *cab = &(cablist[ix]);
    cab->type = type;
    cab->depth = depth;
    switch (type) {
    case 0x02:
      cab->u.ch = Mem1(nodeaddr);
      break;
    case 0x04:
      cab->u.uch = Mem4(nodeaddr);
      break;
    case 0x03:
    case 0x05:
    case 0x0A:
    case 0x0B:
      cab->u.addr = nodeaddr;
      break;
    case 0x08:
    case 0x09:
      cab->u.addr = Mem4(nodeaddr);
      break;
    }
  }
}

#if 0
#include <stdio.h>
static void dumpcache(cacheblock_t *cablist, int count, int indent)
{
  int ix, jx;

  for (ix=0; ix<count; ix++) {
    cacheblock_t *cab = &(cablist[ix]); 
    for (jx=0; jx<indent; jx++)
      printf("  ");
    printf("%X: ", ix);
    switch (cab->type) {
    case 0:
      printf("...\n");
      dumpcache(cab->u.branches, CACHESIZE, indent+1);
      break;
    case 1:
      printf("<EOS>\n");
      break;
    case 2:
      printf("0x%02X", cab->u.ch);
      if (cab->u.ch < 32)
        printf(" ''\n");
      else
        printf(" '%c'\n", cab->u.ch);
      break;
    default:
      printf("type %02X, address %06lX\n", cab->type, cab->u.addr);
      break;
    }
  }
}
#endif /* 0 */

static void dropcache(cacheblock_t *cablist)
{
  int ix;
  for (ix=0; ix<CACHESIZE; ix++) {
    cacheblock_t *cab = &(cablist[ix]);
    if (cab->type == 0) {
      dropcache(cab->u.branches);
      cab->u.branches = NULL;
    }
  }
  glulx_free(cablist);
}

/* This misbehaves if a Glk function has more than one S argument. */

#define STATIC_TEMP_BUFSIZE (127)
static char temp_buf[STATIC_TEMP_BUFSIZE+1];

char *make_temp_string(glui32 addr)
{
  int ix, len;
  glui32 addr2;
  char *res;

  if (Mem1(addr) != 0xE0)
    fatal_error("String argument to a Glk call must be unencoded.");
  addr++;

  for (addr2=addr; Mem1(addr2); addr2++) { };
  len = (addr2 - addr);
  if (len < STATIC_TEMP_BUFSIZE) {
    res = temp_buf;
  }
  else {
    res = (char *)glulx_malloc(len+1);
    if (!res) 
      fatal_error("Unable to allocate space for string argument to Glk call.");
  }
  
  for (ix=0, addr2=addr; ix<len; ix++, addr2++) {
    res[ix] = Mem1(addr2);
  }
  res[len] = '\0';

  return res;
}

glui32 *make_temp_ustring(glui32 addr)
{
  int ix, len;
  glui32 addr2;
  glui32 *res;

  if (Mem1(addr) != 0xE2)
    fatal_error("Ustring argument to a Glk call must be unencoded.");
  addr+=4;

  for (addr2=addr; Mem4(addr2); addr2+=4) { };
  len = (addr2 - addr) / 4;
  if ((len+1)*4 < STATIC_TEMP_BUFSIZE) {
    res = (glui32 *)temp_buf;
  }
  else {
    res = (glui32 *)glulx_malloc((len+1)*4);
    if (!res) 
      fatal_error("Unable to allocate space for ustring argument to Glk call.");
  }
  
  for (ix=0, addr2=addr; ix<len; ix++, addr2+=4) {
    res[ix] = Mem4(addr2);
  }
  res[len] = 0;

  return res;
}

void free_temp_string(char *str)
{
  if (str && str != temp_buf) 
    glulx_free(str);
}

void free_temp_ustring(glui32 *str)
{
  if (str && str != (glui32 *)temp_buf) 
    glulx_free(str);
}