/*
 *----------------------------------------------------------------------
 *
 * DictFilterCmd --
 *
 *	This function implements the "dict filter" Tcl command. See the user
 *	documentation for details on what it does, and TIP#111 for the formal
 *	specification.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
DictFilterCmd(
    ClientData dummy,
    Tcl_Interp *interp,
    int objc,
    Tcl_Obj *const *objv)
{
    Interp *iPtr = (Interp *) interp;
    static const char *const filters[] = {
	"key", "script", "value", NULL
    };
    enum FilterTypes {
	FILTER_KEYS, FILTER_SCRIPT, FILTER_VALUES
    };
    Tcl_Obj *scriptObj, *keyVarObj, *valueVarObj;
    Tcl_Obj **varv, *keyObj = NULL, *valueObj = NULL, *resultObj, *boolObj;
    Tcl_DictSearch search;
    int index, varc, done, result, satisfied;

    if (objc < 3) {
	Tcl_WrongNumArgs(interp, 1, objv, "dictionary filterType ?arg ...?");
	return TCL_ERROR;
    }
    if (Tcl_GetIndexFromObj(interp, objv[2], filters, "filterType",
	     0, &index) != TCL_OK) {
	return TCL_ERROR;
    }

    switch ((enum FilterTypes) index) {
    case FILTER_KEYS:

	/*
	 * Create a dictionary whose keys all match at least one 
	 * of the given patterns.
	 */

	if (Tcl_DictObjFirst(interp, objv[1], &search,
		&keyObj, &valueObj, &done) != TCL_OK) {
	    return TCL_ERROR;
	}
	resultObj = Tcl_NewDictObj();
	while (!done) {
	    int idx;
	    
	    for (idx=3; idx<objc; idx++) {
		if (Tcl_StringMatch(TclGetString(keyObj), 
			TclGetString(objv[idx]))) {
		    Tcl_DictObjPut(interp, resultObj, keyObj, valueObj);
		    break;
		}
	    }
	    Tcl_DictObjNext(&search, &keyObj, &valueObj, &done);
	}
	Tcl_SetObjResult(interp, resultObj);
	return TCL_OK;

    case FILTER_VALUES:

	/*
	 * Create a dictionary whose values all match at least one 
	 * of the given patterns.
	 */

	if (Tcl_DictObjFirst(interp, objv[1], &search,
		&keyObj, &valueObj, &done) != TCL_OK) {
	    return TCL_ERROR;
	}
	resultObj = Tcl_NewDictObj();
	while (!done) {
	    int idx;
	    
	    for (idx=3; idx<objc; idx++) {
		if (Tcl_StringMatch(TclGetString(valueObj), 
			TclGetString(objv[idx]))) {
		    Tcl_DictObjPut(interp, resultObj, keyObj, valueObj);
		    break;
		}
	    }
	    Tcl_DictObjNext(&search, &keyObj, &valueObj, &done);
	}
	Tcl_SetObjResult(interp, resultObj);
	return TCL_OK;

    case FILTER_SCRIPT:
	if (objc != 5) {
	    Tcl_WrongNumArgs(interp, 1, objv,
		    "dictionary script {keyVar valueVar} filterScript");
	    return TCL_ERROR;
	}

	/*
	 * Create a dictionary whose key,value pairs all satisfy a script
	 * (i.e. get a true boolean result from its evaluation). Massive
	 * copying from the "dict for" implementation has occurred!
	 */

	if (TclListObjGetElements(interp, objv[3], &varc, &varv) != TCL_OK) {
	    return TCL_ERROR;
	}
	if (varc != 2) {
	    Tcl_SetResult(interp, "must have exactly two variable names",
		    TCL_STATIC);
	    return TCL_ERROR;
	}
	keyVarObj = varv[0];
	valueVarObj = varv[1];
	scriptObj = objv[4];

	/*
	 * Make sure that these objects (which we need throughout the body of
	 * the loop) don't vanish. Note that the dictionary internal rep is
	 * locked internally so that updates, shimmering, etc are not a
	 * problem.
	 */

	Tcl_IncrRefCount(keyVarObj);
	Tcl_IncrRefCount(valueVarObj);
	Tcl_IncrRefCount(scriptObj);

	result = Tcl_DictObjFirst(interp, objv[1],
		&search, &keyObj, &valueObj, &done);
	if (result != TCL_OK) {
	    TclDecrRefCount(keyVarObj);
	    TclDecrRefCount(valueVarObj);
	    TclDecrRefCount(scriptObj);
	    return TCL_ERROR;
	}

	resultObj = Tcl_NewDictObj();

	while (!done) {
	    /*
	     * Stop the value from getting hit in any way by any traces on the
	     * key variable.
	     */

	    Tcl_IncrRefCount(keyObj);
	    Tcl_IncrRefCount(valueObj);
	    if (Tcl_ObjSetVar2(interp, keyVarObj, NULL, keyObj,
		    TCL_LEAVE_ERR_MSG) == NULL) {
		Tcl_ResetResult(interp);
		Tcl_AppendResult(interp, "couldn't set key variable: \"",
			TclGetString(keyVarObj), "\"", NULL);
		result = TCL_ERROR;
		goto abnormalResult;
	    }
	    if (Tcl_ObjSetVar2(interp, valueVarObj, NULL, valueObj,
		    TCL_LEAVE_ERR_MSG) == NULL) {
		Tcl_ResetResult(interp);
		Tcl_AppendResult(interp, "couldn't set value variable: \"",
			TclGetString(valueVarObj), "\"", NULL);
		goto abnormalResult;
	    }

	    /*
	     * TIP #280. Make invoking context available to loop body.
	     */

	    result = TclEvalObjEx(interp, scriptObj, 0, iPtr->cmdFramePtr, 4);
	    switch (result) {
	    case TCL_OK:
		boolObj = Tcl_GetObjResult(interp);
		Tcl_IncrRefCount(boolObj);
		Tcl_ResetResult(interp);
		if (Tcl_GetBooleanFromObj(interp, boolObj,
			&satisfied) != TCL_OK) {
		    TclDecrRefCount(boolObj);
		    result = TCL_ERROR;
		    goto abnormalResult;
		}
		TclDecrRefCount(boolObj);
		if (satisfied) {
		    Tcl_DictObjPut(interp, resultObj, keyObj, valueObj);
		}
		break;
	    case TCL_BREAK:
		/*
		 * Force loop termination by calling Tcl_DictObjDone; this
		 * makes the next Tcl_DictObjNext say there is nothing more to
		 * do.
		 */

		Tcl_ResetResult(interp);
		Tcl_DictObjDone(&search);
	    case TCL_CONTINUE:
		result = TCL_OK;
		break;
	    case TCL_ERROR:
		Tcl_AppendObjToErrorInfo(interp, Tcl_ObjPrintf(
			"\n    (\"dict filter\" script line %d)",
			interp->errorLine));
	    default:
		goto abnormalResult;
	    }

	    TclDecrRefCount(keyObj);
	    TclDecrRefCount(valueObj);

	    Tcl_DictObjNext(&search, &keyObj, &valueObj, &done);
	}

	/*
	 * Stop holding a reference to these objects.
	 */

	TclDecrRefCount(keyVarObj);
	TclDecrRefCount(valueVarObj);
	TclDecrRefCount(scriptObj);
	Tcl_DictObjDone(&search);

	if (result == TCL_OK) {
	    Tcl_SetObjResult(interp, resultObj);
	} else {
	    TclDecrRefCount(resultObj);
	}
	return result;

    abnormalResult:
	Tcl_DictObjDone(&search);
	TclDecrRefCount(keyObj);
	TclDecrRefCount(valueObj);
	TclDecrRefCount(keyVarObj);
	TclDecrRefCount(valueVarObj);
	TclDecrRefCount(scriptObj);
	TclDecrRefCount(resultObj);
	return result;
    }
    Tcl_Panic("unexpected fallthrough");
    /* Control never reaches this point. */
    return TCL_ERROR;
}