//
// Licensed under Apache License v2.0.  See the file "LICENSE" for more
// information.
//

#include "qpdf-xobject-private.h"
//#include <qpdf/Types.h>
#include <qpdf/QPDF.hh>
#include <qpdf/Pl_Discard.hh>
#include <qpdf/Pl_Count.hh>
#include <qpdf/Pl_Concatenate.hh>
#include "qpdf-tools-private.h"
#include "qpdf-pdftopdf-private.h"

// TODO: need to remove  Struct Parent stuff  (or fix)

// NOTE: use /TrimBox to position content inside Nup cell,
//       /BleedBox to clip against

class CombineFromContents_Provider : public QPDFObjectHandle::StreamDataProvider {
public:
  CombineFromContents_Provider(const std::vector<QPDFObjectHandle> &contents);

  void provideStreamData(int objid, int generation, Pipeline* pipeline);
private:
  std::vector<QPDFObjectHandle> contents;
};

CombineFromContents_Provider::CombineFromContents_Provider(const std::vector<QPDFObjectHandle> &contents)
  : contents(contents)
{
}

void
CombineFromContents_Provider::provideStreamData(int objid,
						int generation,
						Pipeline* pipeline)
{
  Pl_Concatenate concat("concat", pipeline);
  const int clen = contents.size();
  for (int iA = 0; iA < clen; iA ++)
  {
    contents[iA].pipeStreamData(&concat, true, false, false);
    concat << "\n";
  }
  concat.manualFinish();
}

//
//  To convert a page to an XObject there are several keys to consider:
//
//  /Type /Page        -> /Type /XObject (/Type optional for XObject)
//                     -> /Subtype /Form
//                     -> [/FormType 1]  (optional)
//  /Parent ? ? R      -> remove
//  /Resources dict    -> copy
//  /MediaBox rect [/CropBox /BleedBox /TrimBox /ArtBox] 
//                     -> /BBox  (use TrimBox [+ Bleed consideration?], 
//                        with fallback to /MediaBox)
//                        note that /BBox is in *Form Space*, see /Matrix!
//  [/BoxColorInfo dict]   (used for guidelines that may be shown by viewer)
//                     -> ignore/remove
//  [/Contents asfd]   -> concatenate into stream data of the XObject
//                        (page is a dict, XObject a stream)
//
//  [/Rotate 90]   ... must be handled (either use CTM where XObject is
//                        /used/ -- or set /Matrix)
//  [/UserUnit] (PDF 1.6)   -> to /Matrix ?   -- it MUST be handled.
//
//  [/Group dict]      -> copy
//  [/Thumb stream]    -> remove, not needed any more / would have to be
//                        regenerated (combined)
//  [/B]               article beads -- ignore for now
//  [/Dur]             -> remove  (transition duration)
//  [/Trans]           -> remove  (transitions)
//  [/AA]              -> remove  (additional-actions)
//
//  [/Metadata]        what shall we do?? (kill: we can't combine XML)
//  [/PieceInfo]       -> remove, we can't combine private app data (?)
//  [/LastModified  date]  (opt except /PieceInfo)  -> see there
//
//  [/PZ]              -> remove, can't combine/keep (preferred zoom level)
//  [/SeparationInfo]  -> remove, no way to keep this (needed for separation)
//
//  [/ID]              related to web capture -- ignore/kill?
//  [/StructParents]   (opt except pdf contains "structural content items")
//                     -> copy (is this correct?)
//
//  [/Annots]          annotations -- ignore for now
//  [/Tabs]            tab order for annotations (/R row, /C column,
//                     /S structure order) -- see /Annots
//
//  [/TemplateInstantiated]  (reqd, if page was created from named page obj,
//                     1.5) -- ? just ignore?
//  [/PresSteps]       -> remove (sub-page navigation for presentations)
//                     [no subpage navigation for printing / nup]
//  [/VP]              viewport rects -- ignore/drop or recalculate into new
//                     page
//

QPDFObjectHandle
_cfPDFToPDFMakeXObject(QPDF *pdf, QPDFObjectHandle page)
{
  page.assertPageObject();

  QPDFObjectHandle ret = QPDFObjectHandle::newStream(pdf);
  QPDFObjectHandle dict = ret.getDict();

  dict.replaceKey("/Type", QPDFObjectHandle::newName("/XObject")); // optional
  dict.replaceKey("/Subtype", QPDFObjectHandle::newName("/Form")); // required
  // dict.replaceKey("/FormType", QPDFObjectHandle::newInteger(1)); // optional

  QPDFObjectHandle box = _cfPDFToPDFGetTrimBox(page); // already in "form space"
  dict.replaceKey("/BBox", box); // reqd

  // [/Matrix .]   ...  default is [1 0 0 1 0 0]; we incorporate /UserUnit and
  //               /Rotate here
  _cfPDFToPDFMatrix mtx;
  if (page.hasKey("/UserUnit"))
    mtx.scale(page.getKey("/UserUnit").getNumericValue());

  // transform, so that bbox is [0 0 w h]  (in outer space, but after UserUnit)
  pdftopdf_rotation_e rot = _cfPDFToPDFGetRotate(page);
  
  // calculate rotation effect on [0 0 w h]
  _cfPDFToPDFPageRect bbox = _cfPDFToPDFGetBoxAsRect(box),
                      tmp;
  tmp.left = 0;
  tmp.bottom = 0;
  tmp.right = 0;
  tmp.top = 0;
  tmp.rotate_move(rot, bbox.width, bbox.height);
  // tmp.rotate_move moves the bbox; we must achieve this move with the matrix.
  mtx.translate(tmp.left, tmp.bottom); // 1. move origin to end up at
                                       //    left,bottom after rotation

  mtx.rotate(rot);  // 2. rotate coordinates according to /Rotate
  mtx.translate(-bbox.left, -bbox.bottom);  // 3. move origin from 0,0 to
                                            //    "form space"

  dict.replaceKey("/Matrix", mtx.get());

  dict.replaceKey("/Resources", page.getKey("/Resources"));
  if (page.hasKey("/Group"))
    dict.replaceKey("/Group", page.getKey("/Group")); // (transparency); opt,
                                                      // copy if there

  // ?? /StructParents   ... can basically copy from page, but would need
  // fixup in Structure Tree
  // FIXME: remove (globally) Tagged spec (/MarkInfo), and Structure Tree

  // Note: [/Name]  (reqd. only in 1.0 -- but there we even can't use our
  //       normal img/patter procedures)

  // none:
  //  QPDFObjectHandle filter = QPDFObjectHandle::newArray();
  //  QPDFObjectHandle decode_parms = QPDFObjectHandle::newArray();
  // null leads to use of "default filters" from qpdf's settings
  QPDFObjectHandle filter = QPDFObjectHandle::newNull();
  QPDFObjectHandle decode_parms = QPDFObjectHandle::newNull();

  std::vector<QPDFObjectHandle> contents = page.getPageContents();
                                                  // (will assertPageObject)

  auto ph = std::shared_ptr<QPDFObjectHandle::StreamDataProvider>(new CombineFromContents_Provider(contents));
  ret.replaceStreamData(ph, filter, decode_parms);

  return (ret);
}

//
//  we will have to fix up the structure tree (e.g. /K in element), when copying
//    /StructParents;
//  (there is /Pg, which has to point to the containing page, /Stm when it's not
//    part of the page's content stream 
//    i.e. when it is in our XObject!; then there is /StmOwn ...)
//  when not copying, we have to remove the structure tree completely
//    (also /MarkInfo dict)
//  Still this might not be sufficient(?), as there are probably BDC and EMC
//    operators in the stream.
//
//
//   /XObject /Form has
//   [/Type /XObject]
//   /Subtype /Form
//   [/FormType 1]
//   /BBox rect         from crop box, or recalculate
//   [/Matrix .]   ...  default is [1 0 0 1 0 0] ---   we have to incorporate
//                      /UserUnit here?!
//   [/Resources dict]  from page.
//   [/Group dict]      used for transparency -- can copy from page
//   [/Ref dict]        not needed; for external reference
//   [/Metadata]        not, as long we can not combine.
//   [/PieceInfo]       can copy, but not combine 
//   [/LastModified date]    copy if /PieceInfo there
//   [/StructParent]    . don't want to be one   ... have to read more spec
//   [/StructParents]   . copy from page!
//   [/OPI]             no opi version. don't set
//   [/OC]              is this optional content? NO! not needed.
//   [/Name]            (only reqd. in 1.0 -- but there we even can't use our
//                      normal img/patter procedures)
//