#include <petsc/private/viewerimpl.h>   /*I  "petscsys.h"  I*/

typedef struct  {
  char      *string;         /* string where info is stored */
  char      *head;           /* pointer to begining of unused portion */
  size_t    curlen,maxlen;
  PetscBool ownstring;       /* string viewer is responsable for freeing the string */
} PetscViewer_String;

static PetscErrorCode PetscViewerDestroy_String(PetscViewer viewer)
{
  PetscViewer_String *vstr = (PetscViewer_String*)viewer->data;
  PetscErrorCode     ierr;

  PetscFunctionBegin;
  if (vstr->ownstring) {
    ierr = PetscFree(vstr->string);CHKERRQ(ierr);
  }
  ierr = PetscFree(vstr);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/*@C
    PetscViewerStringSPrintf - Prints information to a PetscViewer string.

    Logically Collective on PetscViewer (Hmmm, each processor maintains a separate string)

    Input Parameters:
+   v - a string PetscViewer, formed by PetscViewerStringOpen()
-   format - the format of the input

    Level: developer

    Fortran Note:
    This routine is not supported in Fortran.

.seealso: PetscViewerStringOpen(), PetscViewerStringGetStringRead(), PetscViewerStringSetString(), PETSCVIEWERSTRING
@*/
PetscErrorCode  PetscViewerStringSPrintf(PetscViewer viewer,const char format[],...)
{
  va_list            Argp;
  size_t             fullLength;
  size_t             shift,cshift;
  PetscErrorCode     ierr;
  PetscBool          isstring;
  char               tmp[4096];
  PetscViewer_String *vstr = (PetscViewer_String*)viewer->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,1);
  PetscValidCharPointer(format,2);
  ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
  if (!isstring) PetscFunctionReturn(0);
  if (!vstr->string) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ORDER,"Must call PetscViewerStringSetString() before using");

  va_start(Argp,format);
  ierr = PetscVSNPrintf(tmp,4096,format,&fullLength,Argp);CHKERRQ(ierr);
  va_end(Argp);
  ierr = PetscStrlen(tmp,&shift);CHKERRQ(ierr);
  cshift = shift+1;
  if (cshift >= vstr->maxlen - vstr->curlen - 1) cshift = vstr->maxlen - vstr->curlen - 1;
  ierr = PetscStrncpy(vstr->head,tmp,cshift);CHKERRQ(ierr);
  vstr->head   += shift;
  vstr->curlen += shift;
  PetscFunctionReturn(0);
}

/*@C
    PetscViewerStringOpen - Opens a string as a PetscViewer. This is a very
    simple PetscViewer; information on the object is simply stored into
    the string in a fairly nice way.

    Collective

    Input Parameters:
+   comm - the communicator
.   string - the string to use
-   len    - the string length

    Output Parameter:
.   lab - the PetscViewer

    Level: advanced

    Fortran Note:
    This routine is not supported in Fortran.

.seealso: PetscViewerDestroy(), PetscViewerStringSPrintf(), PetscViewerStringGetStringRead(), PetscViewerStringSetString(), PETSCVIEWERSTRING
@*/
PetscErrorCode  PetscViewerStringOpen(MPI_Comm comm,char string[],size_t len,PetscViewer *lab)
{
  PetscErrorCode ierr;

  PetscFunctionBegin;
  ierr = PetscViewerCreate(comm,lab);CHKERRQ(ierr);
  ierr = PetscViewerSetType(*lab,PETSCVIEWERSTRING);CHKERRQ(ierr);
  ierr = PetscViewerStringSetString(*lab,string,len);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

PetscErrorCode PetscViewerGetSubViewer_String(PetscViewer viewer,MPI_Comm comm,PetscViewer *sviewer)
{
  PetscViewer_String *vstr = (PetscViewer_String*)viewer->data;
  PetscErrorCode     ierr;

  PetscFunctionBegin;
  ierr = PetscViewerStringOpen(PETSC_COMM_SELF,vstr->head,vstr->maxlen-vstr->curlen,sviewer);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

PetscErrorCode PetscViewerRestoreSubViewer_String(PetscViewer viewer,MPI_Comm comm,PetscViewer *sviewer)
{
  PetscErrorCode     ierr;
  PetscViewer_String *iviewer = (PetscViewer_String*)(*sviewer)->data;
  PetscViewer_String *vstr    = (PetscViewer_String*)viewer->data;

  PetscFunctionBegin;
  vstr->head    = iviewer->head;
  vstr->curlen += iviewer->curlen;
  ierr          = PetscViewerDestroy(sviewer);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/*MC
   PETSCVIEWERSTRING - A viewer that writes to a string


.seealso:  PetscViewerStringOpen(), PetscViewerStringSPrintf(), PetscViewerSocketOpen(), PetscViewerDrawOpen(), PETSCVIEWERSOCKET,
           PetscViewerCreate(), PetscViewerASCIIOpen(), PetscViewerBinaryOpen(), PETSCVIEWERBINARY, PETSCVIEWERDRAW,
           PetscViewerMatlabOpen(), VecView(), DMView(), PetscViewerMatlabPutArray(), PETSCVIEWERASCII, PETSCVIEWERMATLAB,
           PetscViewerFileSetName(), PetscViewerFileSetMode(), PetscViewerFormat, PetscViewerType, PetscViewerSetType()

  Level: beginner
M*/

PETSC_EXTERN PetscErrorCode PetscViewerCreate_String(PetscViewer v)
{
  PetscViewer_String *vstr;
  PetscErrorCode     ierr;

  PetscFunctionBegin;
  v->ops->destroy          = PetscViewerDestroy_String;
  v->ops->view             = NULL;
  v->ops->flush            = NULL;
  v->ops->getsubviewer     = PetscViewerGetSubViewer_String;
  v->ops->restoresubviewer = PetscViewerRestoreSubViewer_String;
  ierr                     = PetscNewLog(v,&vstr);CHKERRQ(ierr);
  v->data                  = (void*)vstr;
  vstr->string             = NULL;
  PetscFunctionReturn(0);
}

/*@C

   PetscViewerStringGetStringRead - Returns the string that a string viewer uses

   Logically Collective on PetscViewer

  Input Parameter:
.   viewer - string viewer

  Output Parameters:
+    string - the string, optional use NULL if you do not need
-   len - the length of the string, optional use NULL if you do

  Notes: Do not write to the string nor free it

  Level: advanced

.seealso: PetscViewerStringOpen(), PETSCVIEWERSTRING, PetscViewerStringSetString(), PetscViewerStringSPrintf(),
          PetscViewerStringSetOwnString()
@*/
PetscErrorCode  PetscViewerStringGetStringRead(PetscViewer viewer,const char *string[],size_t *len)
{
  PetscViewer_String *vstr = (PetscViewer_String*)viewer->data;
  PetscErrorCode     ierr;
  PetscBool          isstring;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,1);
  ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
  if (!isstring) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Only for PETSCVIEWERSTRING");
  if (string) *string = vstr->string;
  if (len)    *len    = vstr->maxlen;
  PetscFunctionReturn(0);
}

/*@C

   PetscViewerStringSetString - sets the string that a string viewer will print to

   Logically Collective on PetscViewer

  Input Parameters:
+   viewer - string viewer you wish to attach string to
.   string - the string to print data into
-   len - the length of the string

  Notes: The function does not copy the string, it uses it directly therefore you cannot free
   the string until the viewer is destroyed. If you call PetscViewerStringSetOwnString() the ownership
   passes to the viewer and it will be responsable for freeing it. In this case the string must be
   obtained with PetscMalloc().

  Level: advanced

.seealso: PetscViewerStringOpen(), PETSCVIEWERSTRING, PetscViewerStringGetStringRead(), PetscViewerStringSPrintf(),
          PetscViewerStringSetOwnString()
@*/
PetscErrorCode  PetscViewerStringSetString(PetscViewer viewer,char string[],size_t len)
{
  PetscViewer_String *vstr = (PetscViewer_String*)viewer->data;
  PetscErrorCode     ierr;
  PetscBool          isstring;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,1);
  PetscValidCharPointer(string,2);
  ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
  if (!isstring) PetscFunctionReturn(0);
  if (len <= 2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"String must have length at least 2");

  ierr         = PetscArrayzero(string,len);CHKERRQ(ierr);
  vstr->string = string;
  vstr->head   = string;
  vstr->curlen = 0;
  vstr->maxlen = len;
  PetscFunctionReturn(0);
}

/*@C

   PetscViewerStringSetOwnString - tells the viewer that it now owns the string and is responsible for freeing it

   Logically Collective on PetscViewer

  Input Parameters:
.   viewer - string viewer

  Notes: If you call this the string must have been obtained with PetscMalloc() and you cannot free the string

  Level: advanced

.seealso: PetscViewerStringOpen(), PETSCVIEWERSTRING, PetscViewerStringGetStringRead(), PetscViewerStringSPrintf(),
          PetscViewerStringSetString()
@*/
PetscErrorCode  PetscViewerStringSetOwnString(PetscViewer viewer)
{
  PetscViewer_String *vstr = (PetscViewer_String*)viewer->data;
  PetscErrorCode     ierr;
  PetscBool          isstring;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,1);
  ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
  if (!isstring) PetscFunctionReturn(0);

  vstr->ownstring = PETSC_TRUE;
  PetscFunctionReturn(0);
}