// Copyright 2017 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com

#include "core/fpdfapi/page/cpdf_function.h"

#include <algorithm>
#include <utility>
#include <vector>

#include "core/fpdfapi/page/cpdf_expintfunc.h"
#include "core/fpdfapi/page/cpdf_psfunc.h"
#include "core/fpdfapi/page/cpdf_sampledfunc.h"
#include "core/fpdfapi/page/cpdf_stitchfunc.h"
#include "core/fpdfapi/parser/cpdf_array.h"
#include "core/fpdfapi/parser/cpdf_dictionary.h"
#include "core/fpdfapi/parser/cpdf_stream.h"
#include "core/fpdfapi/parser/fpdf_parser_utility.h"
#include "core/fxcrt/containers/contains.h"
#include "core/fxcrt/fx_safe_types.h"
#include "core/fxcrt/scoped_set_insertion.h"
#include "core/fxcrt/stl_util.h"

namespace {

CPDF_Function::Type IntegerToFunctionType(int iType) {
  switch (iType) {
    case 0:
    case 2:
    case 3:
    case 4:
      return static_cast<CPDF_Function::Type>(iType);
    default:
      return CPDF_Function::Type::kTypeInvalid;
  }
}

}  // namespace

// static
std::unique_ptr<CPDF_Function> CPDF_Function::Load(
    RetainPtr<const CPDF_Object> pFuncObj) {
  VisitedSet visited;
  return Load(std::move(pFuncObj), &visited);
}

// static
std::unique_ptr<CPDF_Function> CPDF_Function::Load(
    RetainPtr<const CPDF_Object> pFuncObj,
    VisitedSet* pVisited) {
  if (!pFuncObj) {
    return nullptr;
  }

  if (pdfium::Contains(*pVisited, pFuncObj)) {
    return nullptr;
  }

  ScopedSetInsertion insertion(pVisited, pFuncObj);

  int iType = -1;
  if (const CPDF_Stream* pStream = pFuncObj->AsStream()) {
    iType = pStream->GetDict()->GetIntegerFor("FunctionType");
  } else if (const CPDF_Dictionary* pDict = pFuncObj->AsDictionary()) {
    iType = pDict->GetIntegerFor("FunctionType");
  }

  std::unique_ptr<CPDF_Function> pFunc;
  Type type = IntegerToFunctionType(iType);
  if (type == Type::kType0Sampled) {
    pFunc = std::make_unique<CPDF_SampledFunc>();
  } else if (type == Type::kType2ExponentialInterpolation) {
    pFunc = std::make_unique<CPDF_ExpIntFunc>();
  } else if (type == Type::kType3Stitching) {
    pFunc = std::make_unique<CPDF_StitchFunc>();
  } else if (type == Type::kType4PostScript) {
    pFunc = std::make_unique<CPDF_PSFunc>();
  }

  if (!pFunc || !pFunc->Init(pFuncObj, pVisited)) {
    return nullptr;
  }

  return pFunc;
}

CPDF_Function::CPDF_Function(Type type) : type_(type) {}

CPDF_Function::~CPDF_Function() = default;

bool CPDF_Function::Init(const CPDF_Object* pObj, VisitedSet* pVisited) {
  const CPDF_Stream* pStream = pObj->AsStream();
  RetainPtr<const CPDF_Dictionary> pDict =
      pStream ? pStream->GetDict() : pdfium::WrapRetain(pObj->AsDictionary());

  RetainPtr<const CPDF_Array> pDomains = pDict->GetArrayFor("Domain");
  if (!pDomains) {
    return false;
  }

  inputs_ = fxcrt::CollectionSize<uint32_t>(*pDomains) / 2;
  if (inputs_ == 0) {
    return false;
  }

  size_t nInputs = inputs_ * 2;
  domains_ = ReadArrayElementsToVector(pDomains.Get(), nInputs);

  RetainPtr<const CPDF_Array> pRanges = pDict->GetArrayFor("Range");
  outputs_ = pRanges ? fxcrt::CollectionSize<uint32_t>(*pRanges) / 2 : 0;

  // Ranges are required for type 0 and type 4 functions. A non-zero
  // |outputs_| here implied Ranges meets the requirements.
  bool bRangeRequired =
      type_ == Type::kType0Sampled || type_ == Type::kType4PostScript;
  if (bRangeRequired && outputs_ == 0) {
    return false;
  }

  if (outputs_ > 0) {
    size_t nOutputs = outputs_ * 2;
    ranges_ = ReadArrayElementsToVector(pRanges.Get(), nOutputs);
  }

  uint32_t old_outputs = outputs_;
  if (!v_Init(pObj, pVisited)) {
    return false;
  }

  if (!ranges_.empty() && outputs_ > old_outputs) {
    FX_SAFE_SIZE_T nOutputs = outputs_;
    nOutputs *= 2;
    ranges_.resize(nOutputs.ValueOrDie());
  }
  return true;
}

std::optional<uint32_t> CPDF_Function::Call(pdfium::span<const float> inputs,
                                            pdfium::span<float> results) const {
  if (inputs_ != inputs.size()) {
    return std::nullopt;
  }

  std::vector<float> clamped_inputs(inputs_);
  for (uint32_t i = 0; i < inputs_; i++) {
    float domain1 = domains_[i * 2];
    float domain2 = domains_[i * 2 + 1];
    if (domain1 > domain2) {
      return std::nullopt;
    }

    clamped_inputs[i] = std::clamp(inputs[i], domain1, domain2);
  }
  if (!v_Call(clamped_inputs, results)) {
    return std::nullopt;
  }

  if (ranges_.empty()) {
    return outputs_;
  }

  for (uint32_t i = 0; i < outputs_; i++) {
    float range1 = ranges_[i * 2];
    float range2 = ranges_[i * 2 + 1];
    if (range1 > range2) {
      return std::nullopt;
    }

    results[i] = std::clamp(results[i], range1, range2);
  }
  return outputs_;
}

// See PDF Reference 1.7, page 170.
float CPDF_Function::Interpolate(float x,
                                 float xmin,
                                 float xmax,
                                 float ymin,
                                 float ymax) const {
  float divisor = xmax - xmin;
  return ymin + (divisor ? (x - xmin) * (ymax - ymin) / divisor : 0);
}

#if defined(PDF_USE_SKIA)
const CPDF_SampledFunc* CPDF_Function::ToSampledFunc() const {
  return type_ == Type::kType0Sampled
             ? static_cast<const CPDF_SampledFunc*>(this)
             : nullptr;
}

const CPDF_ExpIntFunc* CPDF_Function::ToExpIntFunc() const {
  return type_ == Type::kType2ExponentialInterpolation
             ? static_cast<const CPDF_ExpIntFunc*>(this)
             : nullptr;
}

const CPDF_StitchFunc* CPDF_Function::ToStitchFunc() const {
  return type_ == Type::kType3Stitching
             ? static_cast<const CPDF_StitchFunc*>(this)
             : nullptr;
}
#endif  // defined(PDF_USE_SKIA)