/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2; -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef ScriptPreloader_inl_h
#define ScriptPreloader_inl_h

#include "mozilla/Attributes.h"
#include "mozilla/Assertions.h"
#include "mozilla/CheckedInt.h"
#include "mozilla/EndianUtils.h"
#include "mozilla/EnumSet.h"
#include "mozilla/Range.h"
#include "mozilla/ResultExtensions.h"
#include "mozilla/Unused.h"
#include "mozilla/dom/ScriptSettings.h"
#include "nsString.h"
#include "nsTArray.h"

#include <prio.h>

namespace mozilla {

namespace loader {

using mozilla::dom::AutoJSAPI;

static inline Result<Ok, nsresult> Write(PRFileDesc* fd, const void* data,
                                         int32_t len) {
  if (PR_Write(fd, data, len) != len) {
    return Err(NS_ERROR_FAILURE);
  }
  return Ok();
}

struct MOZ_RAII AutoSafeJSAPI : public AutoJSAPI {
  AutoSafeJSAPI() { Init(); }
};

class OutputBuffer {
 public:
  OutputBuffer() {}

  uint8_t* write(size_t size) {
    auto buf = data.AppendElements(size);
    cursor_ += size;
    return buf;
  }

  void codeUint8(const uint8_t& val) { *write(sizeof val) = val; }

  template <typename T>
  void codeUint8(const EnumSet<T>& val) {
    // EnumSets are always represented as uint32_t values, so we need to
    // assert that the value actually fits in a uint8 before writing it.
    uint32_t value = val.serialize();
    codeUint8(CheckedUint8(value).value());
  }

  void codeUint16(const uint16_t& val) {
    LittleEndian::writeUint16(write(sizeof val), val);
  }

  void codeUint32(const uint32_t& val) {
    LittleEndian::writeUint32(write(sizeof val), val);
  }

  void codeString(const nsCString& str) {
    auto len = CheckedUint16(str.Length()).value();

    codeUint16(len);
    memcpy(write(len), str.BeginReading(), len);
  }

  size_t cursor() const { return cursor_; }

  uint8_t* Get() { return data.Elements(); }

  const uint8_t* Get() const { return data.Elements(); }

 private:
  nsTArray<uint8_t> data;
  size_t cursor_ = 0;
};

class InputBuffer {
 public:
  explicit InputBuffer(const Range<uint8_t>& buffer) : data(buffer) {}

  const uint8_t* read(size_t size) {
    MOZ_ASSERT(checkCapacity(size));

    auto buf = &data[cursor_];
    cursor_ += size;
    return buf;
  }

  bool codeUint8(uint8_t& val) {
    if (checkCapacity(sizeof val)) {
      val = *read(sizeof val);
    }
    return !error_;
  }

  template <typename T>
  bool codeUint8(EnumSet<T>& val) {
    uint8_t value;
    if (codeUint8(value)) {
      val.deserialize(value);
    }
    return !error_;
  }

  bool codeUint16(uint16_t& val) {
    if (checkCapacity(sizeof val)) {
      val = LittleEndian::readUint16(read(sizeof val));
    }
    return !error_;
  }

  bool codeUint32(uint32_t& val) {
    if (checkCapacity(sizeof val)) {
      val = LittleEndian::readUint32(read(sizeof val));
    }
    return !error_;
  }

  bool codeString(nsCString& str) {
    uint16_t len;
    if (codeUint16(len)) {
      if (checkCapacity(len)) {
        str.SetLength(len);
        memcpy(str.BeginWriting(), read(len), len);
      }
    }
    return !error_;
  }

  bool error() { return error_; }

  bool finished() { return error_ || !remainingCapacity(); }

  size_t remainingCapacity() { return data.length() - cursor_; }

  size_t cursor() const { return cursor_; }

  const uint8_t* Get() const { return data.begin().get(); }

 private:
  bool checkCapacity(size_t size) {
    if (size > remainingCapacity()) {
      error_ = true;
    }
    return !error_;
  }

  bool error_ = false;

 public:
  const Range<uint8_t>& data;
  size_t cursor_ = 0;
};

template <typename T>
struct Matcher;

// Wraps the iterator for a nsTHashTable so that it may be used as a range
// iterator. Each iterator result acts as a smart pointer to the hash element,
// and has a Remove() method which will remove the element from the hash.
//
// It also accepts an optional Matcher instance against which to filter the
// elements which should be iterated over.
//
// Example:
//
//    for (auto& elem : HashElemIter<HashType>(hash)) {
//        if (elem->IsDead()) {
//            elem.Remove();
//        }
//    }
template <typename T>
class HashElemIter {
  using Iterator = typename T::Iterator;
  using ElemType = typename T::UserDataType;

  T& hash_;
  Matcher<ElemType>* matcher_;
  Maybe<Iterator> iter_;

 public:
  explicit HashElemIter(T& hash, Matcher<ElemType>* matcher = nullptr)
      : hash_(hash), matcher_(matcher) {
    iter_.emplace(std::move(hash.Iter()));
  }

  class Elem {
    friend class HashElemIter<T>;

    HashElemIter<T>& iter_;
    bool done_;

    Elem(HashElemIter& iter, bool done) : iter_(iter), done_(done) {
      skipNonMatching();
    }

    Iterator& iter() { return iter_.iter_.ref(); }

    void skipNonMatching() {
      if (iter_.matcher_) {
        while (!done_ && !iter_.matcher_->Matches(get())) {
          iter().Next();
          done_ = iter().Done();
        }
      }
    }

   public:
    Elem& operator*() { return *this; }

    ElemType get() {
      if (done_) {
        return nullptr;
      }
      return iter().Data();
    }

    const ElemType get() const { return const_cast<Elem*>(this)->get(); }

    ElemType operator->() { return get(); }

    const ElemType operator->() const { return get(); }

    operator ElemType() { return get(); }

    void Remove() { iter().Remove(); }

    Elem& operator++() {
      MOZ_ASSERT(!done_);

      iter().Next();
      done_ = iter().Done();

      skipNonMatching();
      return *this;
    }

    bool operator!=(Elem& other) {
      return done_ != other.done_ || this->get() != other.get();
    }
  };

  Elem begin() { return Elem(*this, iter_->Done()); }

  Elem end() { return Elem(*this, true); }
};

template <typename T>
HashElemIter<T> IterHash(T& hash,
                         Matcher<typename T::UserDataType>* matcher = nullptr) {
  return HashElemIter<T>(hash, matcher);
}

template <typename T, typename F>
bool Find(T&& iter, F&& match) {
  for (auto& elem : iter) {
    if (match(elem)) {
      return true;
    }
  }
  return false;
}

};  // namespace loader
};  // namespace mozilla

#endif  // ScriptPreloader_inl_h