// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Canonicalizers for random bits that aren't big enough for their own files.

#include <string.h>

#include "lib/url/url_canon.h"
#include "lib/url/url_canon_internal.h"

namespace url {

namespace {

// Returns true if the given character should be removed from the middle of a
// URL.
inline bool IsRemovableURLWhitespace(int ch) {
  return ch == '\r' || ch == '\n' || ch == '\t';
}

// Helper functions for converting port integers to strings.
inline void WritePortInt(char* output, int output_len, int port) {
  IntToString(port, output, output_len, 10);
}

// Contains the canonical version of each possible input letter in the scheme
// (basically, lower-cased). The corresponding entry will be 0 if the letter
// is not allowed in a scheme.
// clang-format off
const char kSchemeCanonical[0x80] = {
// 00-1f: all are invalid
     0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
     0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
//  ' '   !    "    #    $    %    &    '    (    )    *    +    ,    -    .    /
     0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,  '+',  0,  '-', '.',  0,
//   0    1    2    3    4    5    6    7    8    9    :    ;    <    =    >    ?
    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',  0 ,  0 ,  0 ,  0 ,  0 ,  0 ,
//   @    A    B    C    D    E    F    G    H    I    J    K    L    M    N    O
     0 , '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    [    \    ]    ^    _
    'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',  0,   0 ,  0,   0 ,  0,
//   `    a    b    c    d    e    f    g    h    i    j    k    l    m    n    o
     0 , '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    {    |    }    ~
    'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',  0 ,  0 ,  0 ,  0 ,  0 };
// clang-format on

// This could be a table lookup as well by setting the high bit for each
// valid character, but it's only called once per URL, and it makes the lookup
// table easier to read not having extra stuff in it.
inline bool IsSchemeFirstChar(unsigned char c) {
  return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
}
}  // namespace

// Backend for RemoveURLWhitespace (see declaration in url_canon.h).
// It sucks that we have to do this, since this takes about 13% of the total URL
// canonicalization time.
const char* RemoveURLWhitespace(const char* input, size_t input_len,
                                CanonOutputT<char>* buffer,
                                size_t* output_len) {
  // Fast verification that there's nothing that needs removal. This is the 99%
  // case, so we want it to be fast and don't care about impacting the speed
  // when we do find whitespace.
  bool found_whitespace = false;
  for (size_t i = 0; i < input_len; i++) {
    if (!IsRemovableURLWhitespace(input[i]))
      continue;
    found_whitespace = true;
    break;
  }

  if (!found_whitespace) {
    // Didn't find any whitespace, we don't need to do anything. We can just
    // return the input as the output.
    *output_len = input_len;
    return input;
  }

  // Remove the whitespace into the new buffer and return it.
  for (size_t i = 0; i < input_len; i++) {
    if (!IsRemovableURLWhitespace(input[i]))
      buffer->push_back(input[i]);
  }
  *output_len = buffer->length();
  return buffer->data();
}

bool CanonicalizeScheme(const char* spec, const Component& scheme,
                        CanonOutput* output, Component* out_scheme) {
  if (scheme.is_invalid_or_empty()) {
    // Scheme is unspecified or empty, convert to empty by appending a colon.
    *out_scheme = Component(output->length(), 0);
    output->push_back(':');
    return true;
  }

  // The output scheme starts from the current position.
  out_scheme->begin = output->length();

  // Danger: it's important that this code does not strip any characters;
  // it only emits the canonical version (be it valid or escaped) for each
  // of the input characters. Stripping would put it out of sync with
  // FindAndCompareScheme, which could cause some security checks on
  // schemes to be incorrect.
  bool success = true;
  size_t end = scheme.end();
  for (size_t i = scheme.begin; i < end; i++) {
    unsigned char ch = static_cast<unsigned char>(spec[i]);
    char replacement = 0;
    if (ch < 0x80) {
      if (i == scheme.begin) {
        // Need to do a special check for the first letter of the scheme.
        if (IsSchemeFirstChar(static_cast<unsigned char>(ch)))
          replacement = kSchemeCanonical[ch];
      } else {
        replacement = kSchemeCanonical[ch];
      }
    }

    if (replacement) {
      output->push_back(replacement);
    } else if (ch == '%') {
      // Canonicalizing the scheme multiple times should lead to the same
      // result. Since invalid characters will be escaped, we need to preserve
      // the percent to avoid multiple escaping. The scheme will be invalid.
      success = false;
      output->push_back('%');
    } else {
      // Invalid character, store it but mark this scheme as invalid.
      success = false;

      // This will escape the output and also handle encoding issues.
      // Ignore the return value since we already failed.
      AppendUTF8EscapedChar(spec, &i, end, output);
    }
  }

  // The output scheme ends with the the current position, before appending
  // the colon.
  out_scheme->set_len(output->length() - out_scheme->begin);
  output->push_back(':');
  return success;
}

// The username and password components reference ranges in the corresponding
// *_spec strings. Typically, these specs will be the same (we're
// canonicalizing a single source string), but may be different when
// replacing components.
bool CanonicalizeUserInfo(const char* username_spec, const Component& username,
                          const char* password_spec, const Component& password,
                          CanonOutput* output, Component* out_username,
                          Component* out_password) {
  if (username.is_invalid_or_empty() && password.is_invalid_or_empty()) {
    // Common case: no user info. We strip empty username/passwords.
    *out_username = Component();
    *out_password = Component();
    return true;
  }

  // Write the username.
  out_username->begin = output->length();
  if (username.is_nonempty()) {
    // This will escape characters not valid for the username.
    AppendStringOfType(&username_spec[username.begin], username.len(),
                       CHAR_USERINFO, output);
  }
  out_username->set_len(output->length() - out_username->begin);

  // When there is a password, we need the separator. Note that we strip
  // empty but specified passwords.
  if (password.is_nonempty()) {
    output->push_back(':');
    out_password->begin = output->length();
    AppendStringOfType(&password_spec[password.begin], password.len(),
                       CHAR_USERINFO, output);
    out_password->set_len(output->length() - out_password->begin);
  } else {
    *out_password = Component();
  }

  output->push_back('@');
  return true;
}

// This function will prepend the colon if there will be a port.
bool CanonicalizePort(const char* spec, const Component& port,
                      int default_port_for_scheme, CanonOutput* output,
                      Component* out_port) {
  int port_num = ParsePort(spec, port);
  if (port_num == PORT_UNSPECIFIED || port_num == default_port_for_scheme) {
    *out_port = Component();
    return true;  // Leave port empty.
  }

  if (port_num == PORT_INVALID) {
    // Invalid port: We'll copy the text from the input so the user can see
    // what the error was, and mark the URL as invalid by returning false.
    output->push_back(':');
    out_port->begin = output->length();
    AppendInvalidNarrowString(spec, port.begin, port.end(), output);
    out_port->set_len(output->length() - out_port->begin);
    return false;
  }

  // Convert port number back to an integer. Max port value is 5 digits, and
  // the Parsed::ExtractPort will have made sure the integer is in range.
  const size_t buf_size = 6;
  char buf[buf_size];
  WritePortInt(buf, buf_size, port_num);

  // Append the port number to the output, preceded by a colon.
  output->push_back(':');
  out_port->begin = output->length();
  for (size_t i = 0; i < buf_size && buf[i]; i++)
    output->push_back(buf[i]);

  out_port->set_len(output->length() - out_port->begin);
  return true;
}

void CanonicalizeRef(const char* spec, const Component& ref,
                     CanonOutput* output, Component* out_ref) {
  if (!ref.is_valid()) {
    // Common case of no ref.
    *out_ref = Component();
    return;
  }

  // Append the ref separator. Note that we need to do this even when the ref
  // is empty but present.
  output->push_back('#');
  out_ref->begin = output->length();

  // Now iterate through all the characters, converting to UTF-8 and validating.
  size_t end = ref.end();
  for (size_t i = ref.begin; i < end; i++) {
    if (spec[i] == 0) {
      // IE just strips NULLs, so we do too.
      continue;
    } else if (static_cast<unsigned char>(spec[i]) < 0x20) {
      // Unline IE seems to, we escape control characters. This will probably
      // make the reference fragment unusable on a web page, but people
      // shouldn't be using control characters in their anchor names.
      AppendEscapedChar(static_cast<unsigned char>(spec[i]), output);
    } else if (static_cast<unsigned char>(spec[i]) < 0x80) {
      // Normal ASCII characters are just appended.
      output->push_back(static_cast<char>(spec[i]));
    } else {
      // Non-ASCII characters are appended unescaped, but only when they are
      // valid. Invalid Unicode characters are replaced with the "invalid
      // character" as IE seems to (ReadUTFChar puts the unicode replacement
      // character in the output on failure for us).
      unsigned code_point;
      ReadUTFChar(spec, &i, end, &code_point);
      AppendUTF8Value(code_point, output);
    }
  }

  out_ref->set_len(output->length() - out_ref->begin);
}

char CanonicalSchemeChar(char ch) {
  return url::kSchemeCanonical[static_cast<int>(ch)];
}

}  // namespace url