#include "quiche/balsa/header_properties.h"

#include <array>
#include <cstdint>

#include "absl/container/flat_hash_set.h"
#include "absl/strings/string_view.h"
#include "quiche/common/quiche_text_utils.h"

namespace quiche::header_properties {

namespace {

// The set of characters allowed in HTTP `token`s. See
// https://datatracker.ietf.org/doc/html/rfc9110#section-5.6.2
inline constexpr unsigned char kValidTokenCharList[] = {
    'A', 'B', 'C',  'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
    'N', 'O', 'P',  'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
    'a', 'b', 'c',  'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
    'n', 'o', 'p',  'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
    '0', '1', '2',  '3', '4', '5', '6', '7', '8', '9', '!', '#', '$',
    '%', '&', '\'', '*', '+', '-', '.', '^', '_', '`', '|', '~'};

using MultivaluedHeadersSet =
    absl::flat_hash_set<absl::string_view, StringPieceCaseHash,
                        StringPieceCaseEqual>;

MultivaluedHeadersSet* buildMultivaluedHeaders() {
  MultivaluedHeadersSet* multivalued_headers = new MultivaluedHeadersSet({
      // clang-format off
      "accept",
      "accept-charset",
      "accept-encoding",
      "accept-language",
      "accept-ranges",
      // The follow four headers are all CORS standard headers
      "access-control-allow-headers",
      "access-control-allow-methods",
      "access-control-expose-headers",
      "access-control-request-headers",
      "allow",
      "cache-control",
      // IETF draft makes this have cache-control syntax
      "cdn-cache-control",
      "connection",
      "content-encoding",
      "content-language",
      "expect",
      "if-match",
      "if-none-match",
      // See RFC 5988 section 5
      "link",
      "pragma",
      "proxy-authenticate",
      "te",
      // Used in the opening handshake of the WebSocket protocol.
      "sec-websocket-extensions",
      // Not mentioned in RFC 2616, but it can have multiple values.
      "set-cookie",
      "trailer",
      "transfer-encoding",
      "upgrade",
      "vary",
      "via",
      "warning",
      "www-authenticate",
      // De facto standard not in the RFCs
      "x-forwarded-for",
      // Internal Google usage gives this cache-control syntax
      "x-go" /**/ "ogle-cache-control",
      // clang-format on
  });
  return multivalued_headers;
}

constexpr std::array<bool, 256> buildInvalidHeaderKeyCharLookupTable() {
  std::array<bool, 256> invalidCharTable{};
  for (uint8_t c : kInvalidHeaderKeyCharList) {
    invalidCharTable[c] = true;
  }
  return invalidCharTable;
}

constexpr std::array<bool, 256>
buildInvalidHeaderKeyCharLookupTableAllowDoubleQuote() {
  std::array<bool, 256> invalidCharTable{};
  for (uint8_t c : kInvalidHeaderKeyCharListAllowDoubleQuote) {
    invalidCharTable[c] = true;
  }
  return invalidCharTable;
}

constexpr std::array<bool, 256> buildInvalidCharLookupTable() {
  std::array<bool, 256> invalidCharTable{};
  for (uint8_t c : kInvalidHeaderCharList) {
    invalidCharTable[c] = true;
  }
  return invalidCharTable;
}

constexpr std::array<bool, 256> kAllTrueArray = {
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true, true, true, true, true, true, true, true, true,
    true, true, true, true};

constexpr std::array<bool, 256> buildInvalidPathCharLookupTable() {
  std::array<bool, 256> invalidCharTable = kAllTrueArray;
  for (uint8_t c : kValidPathCharList) {
    invalidCharTable[c] = false;
  }
  return invalidCharTable;
}

constexpr std::array<bool, 256> buildInvalidQueryCharLookupTable() {
  std::array<bool, 256> invalidCharTable = kAllTrueArray;
  for (uint8_t c : kValidQueryCharList) {
    invalidCharTable[c] = false;
  }
  return invalidCharTable;
}

constexpr std::array<bool, 256> buildValidTokenCharLookupTable() {
  std::array<bool, 256> validTokenCharTable{};
  for (uint8_t c : kValidTokenCharList) {
    validTokenCharTable[c] = true;
  }
  return validTokenCharTable;
}

constexpr std::array<bool, 256> buildValidChunkExtensionValCharLookupTable() {
  std::array<bool, 256> validChunkExtValCharTable = kAllTrueArray;
  constexpr uint8_t US_ASCII_CONTROL_START = 0;
  constexpr uint8_t US_ASCII_CONTROL_END = 32;  // exclusive
  // Valid chunk-ext-val characters are the entire range of visible US-ASCII
  // characters and all extended ASCII characters. Of the control characters,
  // only HTAB is allowed. There are some more precise rules for when DQUOTE
  // and backslash can appear in a quoted-string which we skip here.
  for (uint8_t c = US_ASCII_CONTROL_START; c < US_ASCII_CONTROL_END; ++c) {
    if (c == '\t') {
      continue;
    }
    validChunkExtValCharTable[c] = false;
  }
  // Also exclude the control character DEL.
  validChunkExtValCharTable[127] = false;

  return validChunkExtValCharTable;
}

}  // anonymous namespace

bool IsMultivaluedHeader(absl::string_view header) {
  static const MultivaluedHeadersSet* const multivalued_headers =
      buildMultivaluedHeaders();
  return multivalued_headers->contains(header);
}

bool IsInvalidHeaderKeyChar(uint8_t c) {
  static constexpr std::array<bool, 256> invalidHeaderKeyCharTable =
      buildInvalidHeaderKeyCharLookupTable();

  return invalidHeaderKeyCharTable[c];
}

bool IsInvalidHeaderKeyCharAllowDoubleQuote(uint8_t c) {
  static constexpr std::array<bool, 256> invalidHeaderKeyCharTable =
      buildInvalidHeaderKeyCharLookupTableAllowDoubleQuote();

  return invalidHeaderKeyCharTable[c];
}

bool IsInvalidHeaderChar(uint8_t c) {
  static constexpr std::array<bool, 256> invalidCharTable =
      buildInvalidCharLookupTable();

  return invalidCharTable[c];
}

bool IsValidTokenChar(uint8_t c) {
  static constexpr std::array<bool, 256> validTokenCharTable =
      buildValidTokenCharLookupTable();
  return validTokenCharTable[c];
}

bool IsValidToken(absl::string_view value) {
  if (value.empty()) {
    return false;
  }
  for (const char c : value) {
    if (!IsValidTokenChar(static_cast<uint8_t>(c))) {
      return false;
    }
  }
  return true;
}

bool IsValidChunkExtension(absl::string_view value) {
  for (const char c : value) {
    if (!IsValidChunkExtensionValChar(static_cast<uint8_t>(c))) {
      return false;
    }
  }
  return true;
}

bool IsValidChunkExtensionValChar(uint8_t c) {
  static constexpr std::array<bool, 256> validChunkExtValCharTable =
      buildValidChunkExtensionValCharLookupTable();

  return validChunkExtValCharTable[c];
}

bool HasInvalidHeaderChars(absl::string_view value) {
  for (const char c : value) {
    if (IsInvalidHeaderChar(c)) {
      return true;
    }
  }
  return false;
}

bool HasInvalidPathChar(absl::string_view value) {
  static constexpr std::array<bool, 256> invalidCharTable =
      buildInvalidPathCharLookupTable();
  for (const char c : value) {
    if (invalidCharTable[c]) {
      return true;
    }
  }
  return false;
}

bool HasInvalidQueryChar(absl::string_view value) {
  static constexpr std::array<bool, 256> invalidCharTable =
      buildInvalidQueryCharLookupTable();
  for (const char c : value) {
    if (invalidCharTable[c]) {
      return true;
    }
  }
  return false;
}

}  // namespace quiche::header_properties