+int midend_which_preset(midend *me)
+{
+ char *encoding = me->ourgame->encode_params(me->params, TRUE);
+ int i, ret;
+
+ ret = -1;
+ for (i = 0; i < me->npresets; i++)
+ if (!strcmp(encoding, me->preset_encodings[i])) {
+ ret = i;
+ break;
+ }
+
+ sfree(encoding);
+ return ret;
+}
+
+int midend_wants_statusbar(midend *me)
+{
+ return me->ourgame->wants_statusbar;
+}
+
+void midend_supersede_game_desc(midend *me, char *desc, char *privdesc)
+{
+ sfree(me->desc);
+ sfree(me->privdesc);
+ me->desc = dupstr(desc);
+ me->privdesc = privdesc ? dupstr(privdesc) : NULL;
+}
+
+config_item *midend_get_config(midend *me, int which, char **wintitle)
+{
+ char *titlebuf, *parstr, *rest;
+ config_item *ret;
+ char sep;
+
+ assert(wintitle);
+ titlebuf = snewn(40 + strlen(me->ourgame->name), char);
+
+ switch (which) {
+ case CFG_SETTINGS:
+ sprintf(titlebuf, "%s configuration", me->ourgame->name);
+ *wintitle = titlebuf;
+ return me->ourgame->configure(me->params);
+ case CFG_SEED:
+ case CFG_DESC:
+ if (!me->curparams) {
+ sfree(titlebuf);
+ return NULL;
+ }
+ sprintf(titlebuf, "%s %s selection", me->ourgame->name,
+ which == CFG_SEED ? "random" : "game");
+ *wintitle = titlebuf;
+
+ ret = snewn(2, config_item);
+
+ ret[0].type = C_STRING;
+ if (which == CFG_SEED)
+ ret[0].name = "Game random seed";
+ else
+ ret[0].name = "Game ID";
+ ret[0].ival = 0;
+ /*
+ * For CFG_DESC the text going in here will be a string
+ * encoding of the restricted parameters, plus a colon,
+ * plus the game description. For CFG_SEED it will be the
+ * full parameters, plus a hash, plus the random seed data.
+ * Either of these is a valid full game ID (although only
+ * the former is likely to persist across many code
+ * changes).
+ */
+ parstr = me->ourgame->encode_params(me->curparams, which == CFG_SEED);
+ assert(parstr);
+ if (which == CFG_DESC) {
+ rest = me->desc ? me->desc : "";
+ sep = ':';
+ } else {
+ rest = me->seedstr ? me->seedstr : "";
+ sep = '#';
+ }
+ ret[0].sval = snewn(strlen(parstr) + strlen(rest) + 2, char);
+ sprintf(ret[0].sval, "%s%c%s", parstr, sep, rest);
+ sfree(parstr);
+
+ ret[1].type = C_END;
+ ret[1].name = ret[1].sval = NULL;
+ ret[1].ival = 0;
+
+ return ret;
+ }
+
+ assert(!"We shouldn't be here");
+ return NULL;
+}
+
+static char *midend_game_id_int(midend *me, char *id, int defmode)
+{
+ char *error, *par, *desc, *seed;
+ game_params *newcurparams, *newparams, *oldparams1, *oldparams2;
+ int free_params;
+
+ seed = strchr(id, '#');
+ desc = strchr(id, ':');
+
+ if (desc && (!seed || desc < seed)) {
+ /*
+ * We have a colon separating parameters from game
+ * description. So `par' now points to the parameters
+ * string, and `desc' to the description string.
+ */
+ *desc++ = '\0';
+ par = id;
+ seed = NULL;
+ } else if (seed && (!desc || seed < desc)) {
+ /*
+ * We have a hash separating parameters from random seed.
+ * So `par' now points to the parameters string, and `seed'
+ * to the seed string.
+ */
+ *seed++ = '\0';
+ par = id;
+ desc = NULL;
+ } else {
+ /*
+ * We only have one string. Depending on `defmode', we take
+ * it to be either parameters, seed or description.
+ */
+ if (defmode == DEF_SEED) {
+ seed = id;
+ par = desc = NULL;
+ } else if (defmode == DEF_DESC) {
+ desc = id;
+ par = seed = NULL;
+ } else {
+ par = id;
+ seed = desc = NULL;
+ }
+ }
+
+ /*
+ * We must be reasonably careful here not to modify anything in
+ * `me' until we have finished validating things. This function
+ * must either return an error and do nothing to the midend, or
+ * return success and do everything; nothing in between is
+ * acceptable.
+ */
+ newcurparams = newparams = oldparams1 = oldparams2 = NULL;
+
+ if (par) {
+ newcurparams = me->ourgame->dup_params(me->params);
+ me->ourgame->decode_params(newcurparams, par);
+ error = me->ourgame->validate_params(newcurparams, desc == NULL);
+ if (error) {
+ me->ourgame->free_params(newcurparams);
+ return error;
+ }
+ oldparams1 = me->curparams;
+
+ /*
+ * Now filter only the persistent parts of this state into
+ * the long-term params structure, unless we've _only_
+ * received a params string in which case the whole lot is
+ * persistent.
+ */
+ oldparams2 = me->params;
+ if (seed || desc) {
+ char *tmpstr;
+
+ newparams = me->ourgame->dup_params(me->params);
+
+ tmpstr = me->ourgame->encode_params(newcurparams, FALSE);
+ me->ourgame->decode_params(newparams, tmpstr);
+
+ sfree(tmpstr);
+ } else {
+ newparams = me->ourgame->dup_params(newcurparams);
+ }
+ free_params = TRUE;
+ } else {
+ newcurparams = me->curparams;
+ newparams = me->params;
+ free_params = FALSE;
+ }
+
+ if (desc) {
+ error = me->ourgame->validate_desc(newparams, desc);
+ if (error) {
+ if (free_params) {
+ if (newcurparams)
+ me->ourgame->free_params(newcurparams);
+ if (newparams)
+ me->ourgame->free_params(newparams);
+ }
+ return error;
+ }
+ }
+
+ /*
+ * Now we've got past all possible error points. Update the
+ * midend itself.
+ */
+ me->params = newparams;
+ me->curparams = newcurparams;
+ if (oldparams1)
+ me->ourgame->free_params(oldparams1);
+ if (oldparams2)
+ me->ourgame->free_params(oldparams2);
+
+ sfree(me->desc);
+ sfree(me->privdesc);
+ me->desc = me->privdesc = NULL;
+ sfree(me->seedstr);
+ me->seedstr = NULL;
+
+ if (desc) {
+ me->desc = dupstr(desc);
+ me->genmode = GOT_DESC;
+ sfree(me->aux_info);
+ me->aux_info = NULL;
+ }
+
+ if (seed) {
+ me->seedstr = dupstr(seed);
+ me->genmode = GOT_SEED;
+ }
+
+ return NULL;
+}
+
+char *midend_game_id(midend *me, char *id)
+{
+ return midend_game_id_int(me, id, DEF_PARAMS);
+}
+
+char *midend_get_game_id(midend *me)
+{
+ char *parstr, *ret;
+
+ parstr = me->ourgame->encode_params(me->curparams, FALSE);
+ assert(parstr);
+ assert(me->desc);
+ ret = snewn(strlen(parstr) + strlen(me->desc) + 2, char);
+ sprintf(ret, "%s:%s", parstr, me->desc);
+ sfree(parstr);
+ return ret;
+}
+
+char *midend_set_config(midend *me, int which, config_item *cfg)
+{
+ char *error;
+ game_params *params;
+
+ switch (which) {
+ case CFG_SETTINGS:
+ params = me->ourgame->custom_params(cfg);
+ error = me->ourgame->validate_params(params, TRUE);
+
+ if (error) {
+ me->ourgame->free_params(params);
+ return error;
+ }
+
+ me->ourgame->free_params(me->params);
+ me->params = params;
+ break;
+
+ case CFG_SEED:
+ case CFG_DESC:
+ error = midend_game_id_int(me, cfg[0].sval,
+ (which == CFG_SEED ? DEF_SEED : DEF_DESC));
+ if (error)
+ return error;
+ break;
+ }
+
+ return NULL;
+}
+
+int midend_can_format_as_text_now(midend *me)
+{
+ if (me->ourgame->can_format_as_text_ever)
+ return me->ourgame->can_format_as_text_now(me->params);
+ else
+ return FALSE;
+}
+
+char *midend_text_format(midend *me)
+{
+ if (me->ourgame->can_format_as_text_ever && me->statepos > 0 &&
+ me->ourgame->can_format_as_text_now(me->params))
+ return me->ourgame->text_format(me->states[me->statepos-1].state);
+ else
+ return NULL;
+}
+
+char *midend_solve(midend *me)
+{
+ game_state *s;
+ char *msg, *movestr;
+
+ if (!me->ourgame->can_solve)
+ return "This game does not support the Solve operation";
+
+ if (me->statepos < 1)
+ return "No game set up to solve"; /* _shouldn't_ happen! */
+
+ msg = NULL;
+ movestr = me->ourgame->solve(me->states[0].state,
+ me->states[me->statepos-1].state,
+ me->aux_info, &msg);
+ if (!movestr) {
+ if (!msg)
+ msg = "Solve operation failed"; /* _shouldn't_ happen, but can */
+ return msg;
+ }
+ s = me->ourgame->execute_move(me->states[me->statepos-1].state, movestr);
+ assert(s);
+
+ /*
+ * Now enter the solved state as the next move.
+ */
+ midend_stop_anim(me);
+ while (me->nstates > me->statepos) {
+ me->ourgame->free_game(me->states[--me->nstates].state);
+ if (me->states[me->nstates].movestr)
+ sfree(me->states[me->nstates].movestr);
+ }
+ ensure(me);
+ me->states[me->nstates].state = s;
+ me->states[me->nstates].movestr = movestr;
+ me->states[me->nstates].movetype = SOLVE;
+ me->statepos = ++me->nstates;
+ if (me->ui)
+ me->ourgame->changed_state(me->ui,
+ me->states[me->statepos-2].state,
+ me->states[me->statepos-1].state);
+ me->dir = +1;
+ if (me->ourgame->flags & SOLVE_ANIMATES) {
+ me->oldstate = me->ourgame->dup_game(me->states[me->statepos-2].state);
+ me->anim_time =
+ me->ourgame->anim_length(me->states[me->statepos-2].state,
+ me->states[me->statepos-1].state,
+ +1, me->ui);
+ me->anim_pos = 0.0;
+ } else {
+ me->anim_time = 0.0;
+ midend_finish_move(me);
+ }
+ midend_redraw(me);
+ midend_set_timer(me);
+ return NULL;
+}
+
+char *midend_rewrite_statusbar(midend *me, char *text)
+{
+ /*
+ * An important special case is that we are occasionally called
+ * with our own laststatus, to update the timer.
+ */
+ if (me->laststatus != text) {
+ sfree(me->laststatus);
+ me->laststatus = dupstr(text);
+ }
+
+ if (me->ourgame->is_timed) {
+ char timebuf[100], *ret;
+ int min, sec;
+
+ sec = (int)me->elapsed;
+ min = sec / 60;
+ sec %= 60;
+ sprintf(timebuf, "[%d:%02d] ", min, sec);
+
+ ret = snewn(strlen(timebuf) + strlen(text) + 1, char);
+ strcpy(ret, timebuf);
+ strcat(ret, text);
+ return ret;
+
+ } else {
+ return dupstr(text);
+ }
+}
+
+#define SERIALISE_MAGIC "Simon Tatham's Portable Puzzle Collection"
+#define SERIALISE_VERSION "1"
+
+void midend_serialise(midend *me,
+ void (*write)(void *ctx, void *buf, int len),
+ void *wctx)
+{
+ int i;
+
+ /*
+ * Each line of the save file contains three components. First
+ * exactly 8 characters of header word indicating what type of
+ * data is contained on the line; then a colon followed by a
+ * decimal integer giving the length of the main string on the
+ * line; then a colon followed by the string itself (exactly as
+ * many bytes as previously specified, no matter what they
+ * contain). Then a newline (of reasonably flexible form).
+ */
+#define wr(h,s) do { \
+ char hbuf[80]; \
+ char *str = (s); \
+ sprintf(hbuf, "%-8.8s:%d:", (h), (int)strlen(str)); \
+ write(wctx, hbuf, strlen(hbuf)); \
+ write(wctx, str, strlen(str)); \
+ write(wctx, "\n", 1); \
+} while (0)
+
+ /*
+ * Magic string identifying the file, and version number of the
+ * file format.
+ */
+ wr("SAVEFILE", SERIALISE_MAGIC);
+ wr("VERSION", SERIALISE_VERSION);
+
+ /*
+ * The game name. (Copied locally to avoid const annoyance.)
+ */
+ {
+ char *s = dupstr(me->ourgame->name);
+ wr("GAME", s);
+ sfree(s);
+ }
+
+ /*
+ * The current long-term parameters structure, in full.
+ */
+ if (me->params) {
+ char *s = me->ourgame->encode_params(me->params, TRUE);
+ wr("PARAMS", s);
+ sfree(s);
+ }
+
+ /*
+ * The current short-term parameters structure, in full.
+ */
+ if (me->curparams) {
+ char *s = me->ourgame->encode_params(me->curparams, TRUE);
+ wr("CPARAMS", s);
+ sfree(s);
+ }
+
+ /*
+ * The current game description, the privdesc, and the random seed.
+ */
+ if (me->seedstr)
+ wr("SEED", me->seedstr);
+ if (me->desc)
+ wr("DESC", me->desc);
+ if (me->privdesc)
+ wr("PRIVDESC", me->privdesc);
+
+ /*
+ * The game's aux_info. We obfuscate this to prevent spoilers
+ * (people are likely to run `head' or similar on a saved game
+ * file simply to find out what it is, and don't necessarily
+ * want to be told the answer to the puzzle!)
+ */
+ if (me->aux_info) {
+ unsigned char *s1;
+ char *s2;
+ int len;
+
+ len = strlen(me->aux_info);
+ s1 = snewn(len, unsigned char);
+ memcpy(s1, me->aux_info, len);
+ obfuscate_bitmap(s1, len*8, FALSE);
+ s2 = bin2hex(s1, len);
+
+ wr("AUXINFO", s2);
+
+ sfree(s2);
+ sfree(s1);
+ }
+
+ /*
+ * Any required serialisation of the game_ui.
+ */
+ if (me->ui) {
+ char *s = me->ourgame->encode_ui(me->ui);
+ if (s) {
+ wr("UI", s);
+ sfree(s);
+ }
+ }
+
+ /*
+ * The game time, if it's a timed game.
+ */
+ if (me->ourgame->is_timed) {
+ char buf[80];
+ sprintf(buf, "%g", me->elapsed);
+ wr("TIME", buf);
+ }
+
+ /*
+ * The length of, and position in, the states list.
+ */
+ {
+ char buf[80];
+ sprintf(buf, "%d", me->nstates);
+ wr("NSTATES", buf);
+ sprintf(buf, "%d", me->statepos);
+ wr("STATEPOS", buf);
+ }
+
+ /*
+ * For each state after the initial one (which we know is
+ * constructed from either privdesc or desc), enough
+ * information for execute_move() to reconstruct it from the
+ * previous one.
+ */
+ for (i = 1; i < me->nstates; i++) {
+ assert(me->states[i].movetype != NEWGAME); /* only state 0 */
+ switch (me->states[i].movetype) {
+ case MOVE:
+ wr("MOVE", me->states[i].movestr);
+ break;
+ case SOLVE:
+ wr("SOLVE", me->states[i].movestr);
+ break;
+ case RESTART:
+ wr("RESTART", me->states[i].movestr);
+ break;
+ }
+ }
+
+#undef wr
+}
+
+/*
+ * This function returns NULL on success, or an error message.
+ */
+char *midend_deserialise(midend *me,
+ int (*read)(void *ctx, void *buf, int len),
+ void *rctx)