/*
   Context management functions.
   A context is a set of data used to
   - handle help requests,
   - displaying status info,
   - process keystrokes.
*/

#include "common.h"

typedef struct {
  CharPtr HelpCode;
  KeyProc KeyAction;
  CharPtr Text;
} Context;

Local(ByteStorePtr) ContextStack=NULL;

Local(Context) context;

Local(void) ProcessKey(Char);

/* Sets a new context */
Global(void) PushContext(CharPtr HelpCode, KeyProc KeyAction, CharPtr Text) {
  if (!ContextStack) {
    ContextStack=BSNew(sizeof(Context));
    KeyboardView(ProcessKey);
  }
  context.HelpCode=_StringSave(HelpCode);
  context.KeyAction=KeyAction;
  context.Text=_StringSave(Text);
  BSSeek(ContextStack,0,SEEK_SET);
  BSInsert(ContextStack,&context,sizeof(Context));
  UpdateInfoInMainWindow(MWI_STATUS,Text);
}

/* Restores previuos context */
Global(void) PopContext(void) {
  _MemFree(context.HelpCode);
  _MemFree(context.Text);
  BSSeek(ContextStack,0,SEEK_SET);
  BSDelete(ContextStack,sizeof(Context));
  if (BSLen(ContextStack)) {
    BSRead(ContextStack,&context,sizeof(Context));
    UpdateInfoInMainWindow(MWI_STATUS,context.Text);
  } else {
    ContextStack=BSFree(ContextStack);
    KeyboardView(NULL);
  }
}

/* Processes a keystroke in the current context */
Local(void) ProcessKey(Char key) {
  if (context.KeyAction) context.KeyAction(key);
}

Global(CharPtr) GetHelpKey(void) {
  return context.HelpCode;
}