// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_BASE_HASH_VALUE_H_
#define NET_BASE_HASH_VALUE_H_

#include <stddef.h>
#include <stdint.h>

#include <array>
#include <string>
#include <string_view>
#include <vector>

#include "base/containers/span.h"
#include "build/build_config.h"
#include "net/base/net_export.h"

namespace net {

using SHA256HashValue = std::array<uint8_t, 32>;

enum HashValueTag {
  HASH_VALUE_SHA256,
};

class NET_EXPORT HashValue {
 public:
  using iterator = base::span<uint8_t>::iterator;
  using const_iterator = base::span<const uint8_t>::iterator;

  explicit HashValue(const SHA256HashValue& hash);
  // `hash` must match the size of a `SHA256HashValue`.
  explicit HashValue(base::span<const uint8_t> hash);
  explicit HashValue(HashValueTag tag) : tag_(tag) {}
  HashValue() : tag_(HASH_VALUE_SHA256) {}

  // Serializes/Deserializes hashes in the form of
  // <hash-name>"/"<base64-hash-value>
  // (eg: "sha256/...")
  // This format may be persisted to permanent storage, so
  // care should be taken before changing the serialization.
  //
  // This format is used for:
  //   - net_internals display/setting public-key pins
  //   - logging public-key pins
  //   - serializing public-key pins

  // Deserializes a HashValue from a string. Returns false if the input is not
  // valid.
  bool FromString(std::string_view input);

  // Serializes the HashValue to a string.
  std::string ToString() const;

  // These return the bytes of the contained hash value.
  base::span<uint8_t> span();
  base::span<const uint8_t> span() const;

  // Returns the SHA256 byte array. CHECK-fails if tag() != HASH_VALUE_SHA256;
  const SHA256HashValue& sha256hashvalue() const;

  HashValueTag tag() const { return tag_; }

  NET_EXPORT friend bool operator==(const HashValue& lhs, const HashValue& rhs);
  NET_EXPORT friend bool operator<(const HashValue& lhs, const HashValue& rhs);
  NET_EXPORT friend bool operator>(const HashValue& lhs, const HashValue& rhs);
  NET_EXPORT friend bool operator<=(const HashValue& lhs, const HashValue& rhs);
  NET_EXPORT friend bool operator>=(const HashValue& lhs, const HashValue& rhs);

 private:
  HashValueTag tag_;

  union {
    SHA256HashValue sha256;
  } fingerprint;
};

typedef std::vector<HashValue> HashValueVector;

}  // namespace net

#endif  // NET_BASE_HASH_VALUE_H_