/*

 * Copyright 2014 Google Inc. All rights reserved.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include <assert.h>

#include <stddef.h>

#include <stdint.h>

#include <algorithm>

#include <clocale>

#include <memory>

#include <regex>

#include <string>

#include "flatbuffers/idl.h"

#include "test_init.h"

static constexpr size_t kMinInputLength = 1;

static constexpr size_t kMaxInputLength = 3000;

static constexpr uint8_t flags_scalar_type = 0x0F;  // type of scalar value

static constexpr uint8_t flags_quotes_kind = 0x10;  // quote " or '

// reserved for future: json {named} or [unnamed]

// static constexpr uint8_t flags_json_bracer = 0x20;

// Find all 'subj' sub-strings and replace first character of sub-string.

// BreakSequence("testest","tes", 'X') -> "XesXest".

// BreakSequence("xxx","xx", 'Y') -> "YYx".

static void BreakSequence(std::string &s, const char *subj, char repl) {

  size_t pos = 0;

  while (pos = s.find(subj, pos), pos != std::string::npos) {

    s.at(pos) = repl;

    pos++;

  }

}

// Remove all leading and trailing symbols matched with pattern set.

// StripString("xy{xy}y", "xy") -> "{xy}"

static std::string StripString(const std::string &s, const char *pattern,

                               size_t *pos = nullptr) {

  if (pos) *pos = 0;

  // leading

  auto first = s.find_first_not_of(pattern);

  if (std::string::npos == first) return "";

  if (pos) *pos = first;

  // trailing

  auto last = s.find_last_not_of(pattern);

  assert(last < s.length());

  assert(first <= last);

  return s.substr(first, last - first + 1);

}

class RegexMatcher {

 protected:

  virtual bool MatchNumber(const std::string &input) const = 0;

 public:

  virtual ~RegexMatcher() = default;

  struct MatchResult {

    size_t pos{ 0 };

    size_t len{ 0 };

    bool res{ false };

    bool quoted{ false };

  };

  MatchResult Match(const std::string &input) const {

    MatchResult r;

    // strip leading and trailing "spaces" accepted by flatbuffer

    auto test = StripString(input, "\t\r\n ", &r.pos);

    r.len = test.size();

    // check quotes

    if (test.size() >= 2) {

      auto fch = test.front();

      auto lch = test.back();

      r.quoted = (fch == lch) && (fch == '\'' || fch == '\"');

      if (r.quoted) {

        // remove quotes for regex test

        test = test.substr(1, test.size() - 2);

      }

    }

    // Fast check:

    if (test.empty()) return r;

    // A string with a valid scalar shouldn't have non-ascii or non-printable

    // symbols.

    for (auto c : test) {

      if ((c < ' ') || (c > '~')) return r;

    }

    // Check with regex

    r.res = MatchNumber(test);

    return r;

  }

  bool MatchRegexList(const std::string &input,

                      const std::vector<std::regex> &re_list) const {

    auto str = StripString(input, " ");

    if (str.empty()) return false;

    for (auto &re : re_list) {

      std::smatch match;

      if (std::regex_match(str, match, re)) return true;

    }

    return false;

  }

};

class IntegerRegex : public RegexMatcher {

 protected:

  bool MatchNumber(const std::string &input) const override {

    static const std::vector<std::regex> re_list = {

      std::regex{ R"(^[-+]?[0-9]+$)", std::regex_constants::optimize },

      std::regex{ R"(^[-+]?0[xX][0-9a-fA-F]+$)",

                  std::regex_constants::optimize }

    };

    return MatchRegexList(input, re_list);

  }

 public:

  IntegerRegex() = default;

  virtual ~IntegerRegex() = default;

};

class UIntegerRegex : public RegexMatcher {

 protected:

  bool MatchNumber(const std::string &input) const override {

    static const std::vector<std::regex> re_list = {

      std::regex{ R"(^[+]?[0-9]+$)", std::regex_constants::optimize },

      std::regex{ R"(^[+]?0[xX][0-9a-fA-F]+$)",

                  std::regex_constants::optimize },

      // accept -0 number

      std::regex{ R"(^[-](?:0[xX])?0+$)", std::regex_constants::optimize }

    };

    return MatchRegexList(input, re_list);

  }

 public:

  UIntegerRegex() = default;

  virtual ~UIntegerRegex() = default;

};

class BooleanRegex : public IntegerRegex {

 protected:

  bool MatchNumber(const std::string &input) const override {

    if (input == "true" || input == "false") return true;

    return IntegerRegex::MatchNumber(input);

  }

 public:

  BooleanRegex() = default;

  virtual ~BooleanRegex() = default;

};

class FloatRegex : public RegexMatcher {

 protected:

  bool MatchNumber(const std::string &input) const override {

    static const std::vector<std::regex> re_list = {

      // hex-float

      std::regex{

          R"(^[-+]?0[xX](?:(?:[.][0-9a-fA-F]+)|(?:[0-9a-fA-F]+[.][0-9a-fA-F]*)|(?:[0-9a-fA-F]+))[pP][-+]?[0-9]+$)",

          std::regex_constants::optimize },

      // dec-float

      std::regex{

          R"(^[-+]?(?:(?:[.][0-9]+)|(?:[0-9]+[.][0-9]*)|(?:[0-9]+))(?:[eE][-+]?[0-9]+)?$)",

          std::regex_constants::optimize },

      std::regex{ R"(^[-+]?(?:nan|inf|infinity)$)",

                  std::regex_constants::optimize | std::regex_constants::icase }

    };

    return MatchRegexList(input, re_list);

  }

 public:

  FloatRegex() = default;

  virtual ~FloatRegex() = default;

};

class ScalarReferenceResult {

 private:

  ScalarReferenceResult(const char *_type, RegexMatcher::MatchResult _matched)

      : type(_type), matched(_matched) {}

 public:

  // Decode scalar type and check if the input string satisfies the scalar type.

  static ScalarReferenceResult Check(uint8_t code, const std::string &input) {

    switch (code) {

      case 0x0: return { "double", FloatRegex().Match(input) };

      case 0x1: return { "float", FloatRegex().Match(input) };

      case 0x2: return { "int8", IntegerRegex().Match(input) };

      case 0x3: return { "int16", IntegerRegex().Match(input) };

      case 0x4: return { "int32", IntegerRegex().Match(input) };

      case 0x5: return { "int64", IntegerRegex().Match(input) };

      case 0x6: return { "uint8", UIntegerRegex().Match(input) };

      case 0x7: return { "uint16", UIntegerRegex().Match(input) };

      case 0x8: return { "uint32", UIntegerRegex().Match(input) };

      case 0x9: return { "uint64", UIntegerRegex().Match(input) };

      case 0xA: return { "bool", BooleanRegex().Match(input) };

      default: return { "float", FloatRegex().Match(input) };

    };

  }

  const char *type;

  const RegexMatcher::MatchResult matched;

};

bool Parse(flatbuffers::Parser &parser, const std::string &json,

           std::string *_text) {

  auto done = parser.ParseJson(json.c_str());

  if (done) {

    TEST_NULL(GenText(parser, parser.builder_.GetBufferPointer(), _text));

  } else {

    *_text = parser.error_;

  }

  return done;

}

// Utility for test run.

OneTimeTestInit OneTimeTestInit::one_time_init_;

// llvm std::regex have problem with stack overflow, limit maximum length.

// ./scalar_fuzzer -max_len=3000

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {

  // Reserve one byte for Parser flags and one byte for repetition counter.

  if (size < 3) return 0;

  const uint8_t flags = data[0];

  // normalize to ascii alphabet

  const int extra_rep_number =

      std::max(5, (data[1] > '0' ? (data[1] - '0') : 0));

  data += 2;

  size -= 2;  // bypass

  // Guarantee 0-termination.

  const std::string original(reinterpret_cast<const char *>(data), size);

  auto input = std::string(original.c_str());  // until '\0'

  if (input.size() < kMinInputLength || input.size() > kMaxInputLength)

    return 0;

  // Break comments in json to avoid complexity with regex matcher.

  // The string " 12345 /* text */" will be accepted if insert it to string

  // expression: "table X { Y: " + " 12345 /* text */" + "; }.

  // But strings like this will complicate regex matcher.

  // We reject this by transform "/* text */ 12345" to "@* text */ 12345".

  BreakSequence(input, "//", '@');  // "//" -> "@/"

  BreakSequence(input, "/*", '@');  // "/*" -> "@*"

  // { "$schema: "text" } is exceptional case.

  // This key:value ignored by the parser. Numbers can not have $.

  BreakSequence(input, "$schema", '@');  // "$schema" -> "@schema"

  // Break all known scalar functions (todo: add them to regex?):

  for (auto f : { "deg", "rad", "sin", "cos", "tan", "asin", "acos", "atan" }) {

    BreakSequence(input, f, '_');  // ident -> ident

  }

  // Extract type of scalar from 'flags' and check if the input string satisfies

  // the scalar type.

  const auto ref_res =

      ScalarReferenceResult::Check(flags & flags_scalar_type, input);

  auto &recheck = ref_res.matched;

  // Create parser

  flatbuffers::IDLOptions opts;

  opts.force_defaults = true;

  opts.output_default_scalars_in_json = true;

  opts.indent_step = -1;

  opts.strict_json = true;

  flatbuffers::Parser parser(opts);

  auto schema =

      "table X { Y: " + std::string(ref_res.type) + "; } root_type X;";

  TEST_EQ_FUNC(parser.Parse(schema.c_str()), true);

  // The fuzzer can adjust the number repetition if a side-effects have found.

  // Each test should pass at least two times to ensure that the parser doesn't

  // have any hidden-states or locale-depended effects.

  for (auto cnt = 0; cnt < (extra_rep_number + 2); cnt++) {

    // Each even run (0,2,4..) will test locale independed code.

    auto use_locale = !!OneTimeTestInit::test_locale() && (0 == (cnt % 2));

    // Set new locale.

    if (use_locale) {

      FLATBUFFERS_ASSERT(setlocale(LC_ALL, OneTimeTestInit::test_locale()));

    }

    // Parse original input as-is.

    auto orig_scalar = "{\"Y\" : " + input + "}";

    std::string orig_back;

    auto orig_done = Parse(parser, orig_scalar, &orig_back);

    if (recheck.res != orig_done) {

      // look for "does not fit" or "doesn't fit" or "out of range"

      auto not_fit =

          (true == recheck.res)

              ? ((orig_back.find("does not fit") != std::string::npos) ||

                 (orig_back.find("out of range") != std::string::npos))

              : false;

      if (false == not_fit) {

        TEST_OUTPUT_LINE("Stage 1 failed: Parser(%d) != Regex(%d)", orig_done,

                         recheck.res);

        TEST_EQ_STR(orig_back.c_str(),

                    input.substr(recheck.pos, recheck.len).c_str());

        TEST_EQ_FUNC(orig_done, recheck.res);

      }

    }

    // Try to make quoted string and test it.

    std::string qouted_input;

    if (true == recheck.quoted) {

      // we can't simply remove quotes, they may be nested "'12'".

      // Original string "\'12\'" converted to "'12'".

      // The string can be an invalid string by JSON rules, but after quotes

      // removed can transform to valid.

      assert(recheck.len >= 2);

    } else {

      const auto quote = (flags & flags_quotes_kind) ? '\"' : '\'';

      qouted_input = input;  // copy

      qouted_input.insert(recheck.pos + recheck.len, 1, quote);

      qouted_input.insert(recheck.pos, 1, quote);

    }

    // Test quoted version of the string

    if (!qouted_input.empty()) {

      auto fix_scalar = "{\"Y\" : " + qouted_input + "}";

      std::string fix_back;

      auto fix_done = Parse(parser, fix_scalar, &fix_back);

      if (orig_done != fix_done) {

        TEST_OUTPUT_LINE("Stage 2 failed: Parser(%d) != Regex(%d)", fix_done,

                         orig_done);

        TEST_EQ_STR(fix_back.c_str(), orig_back.c_str());

      }

      if (orig_done) { TEST_EQ_STR(fix_back.c_str(), orig_back.c_str()); }

      TEST_EQ_FUNC(fix_done, orig_done);

    }

    // Create new parser and test default value

    if (true == orig_done) {

      flatbuffers::Parser def_parser(opts);  // re-use options

      auto def_schema = "table X { Y: " + std::string(ref_res.type) + " = " +

                        input + "; } root_type X;" +

                        "{}";  // <- with empty json {}!

      auto def_done = def_parser.Parse(def_schema.c_str());

      if (false == def_done) {

        TEST_OUTPUT_LINE("Stage 3.1 failed with _error = %s",

                         def_parser.error_.c_str());

        FLATBUFFERS_ASSERT(false);

      }

      // Compare with print.

      std::string ref_string, def_string;

      FLATBUFFERS_ASSERT(!GenText(

          parser, parser.builder_.GetBufferPointer(), &ref_string));

      FLATBUFFERS_ASSERT(!GenText(

          def_parser, def_parser.builder_.GetBufferPointer(), &def_string));

      if (ref_string != def_string) {

        TEST_OUTPUT_LINE("Stage 3.2 failed: '%s' != '%s'", def_string.c_str(),

                         ref_string.c_str());

        FLATBUFFERS_ASSERT(false);

      }

    }

    // Restore locale.

    if (use_locale) { FLATBUFFERS_ASSERT(setlocale(LC_ALL, "C")); }

  }

  return 0;

}