// Copyright 2018 Google LLC. All Rights Reserved. This file and proprietary
// source code may only be used and distributed under the Widevine Master
// License Agreement.

#ifndef ECM_PARSER_H
#define ECM_PARSER_H

#include <memory>
#include <vector>

#include "cas_types.h"

namespace wvcas {

enum class KeySlotId { kEvenKeySlot, kOddKeySlot };

struct EcmKeyData;

// EcmParser allows random access to the fields of an ECM.
// The only validation performed is to ensure that the ecm
// passed in is large enough to hold a single key entry.
class EcmParser {
 protected:
  EcmParser() {}

 public:
  virtual ~EcmParser() {}

  // The EcmParser factory method.
  // Validates the ecm. If validations is successful returns true and constructs
  // an EcmParser in |parser| using |ecm|.
  static bool create(const CasEcm& ecm,
                     std::unique_ptr<const EcmParser>* parser);

  // Accessor methods.
  virtual uint8_t version() const;
  virtual uint8_t sequence_count() const;
  virtual CryptoMode crypto_mode() const;
  virtual bool rotation_enabled() const;
  virtual size_t content_iv_size() const;
  virtual uint8_t age_restriction() const;
  virtual const std::vector<uint8_t> entitlement_key_id(KeySlotId id) const;
  virtual const std::vector<uint8_t> content_key_id(KeySlotId id) const;
  virtual const std::vector<uint8_t> wrapped_key_data(KeySlotId id) const;
  virtual const std::vector<uint8_t> wrapped_key_iv(KeySlotId id) const;
  virtual const std::vector<uint8_t> content_iv(KeySlotId id) const;

  EcmParser(const EcmParser&) = delete;
  EcmParser& operator=(const EcmParser&) = delete;

 private:
  // Constructs an EcmParser using |ecm|.
  explicit EcmParser(const CasEcm& ecm);

  size_t key_data_size() const;
  // Returns false if the ecm used to construct the object is not a valid size.
  // TODO(jfore): Add validation using the version field.
  bool is_valid_size() const;
  const EcmKeyData* key_slot_data(KeySlotId id) const;

  CasEcm ecm_;
};

}  // namespace wvcas

#endif  // ECM_PARSER_H