/*

 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

/*

 * This is not really json in the state it is now.

 * Some differences:

 * - Double quotes around the key in an object is not enforced.

 *     i.e you can write: { foo : "bar" } instead of { "foo" : "bar" }.

 * - Comments are allowed.

 * - The last element in an object or array can have an ending comma.

 */

#include "precompiled.hpp"

#include "utilities/json.hpp"

#include "utilities/ostream.hpp"

#include <math.h>

const char* strchrnul_(const char *s, int c) {

  const char* tmp = strchr(s, c);

  return tmp == NULL ? s + strlen(s) : tmp;

}

JSON::JSON(const char* text, bool silent, outputStream* st)

: start(text), pos(text), mark(text),

  level(0), line(1), column(0), silent(silent), _valid(true), _st(st)

{

}

void JSON::parse() {

  assert(start != NULL, "Need something to parse");

  if (start == NULL) {

    _valid = false;

    error(INTERNAL_ERROR, "JSON parser was called with a string that was NULL.");

  } else {

    _valid = parse_json_value();

  }

}

bool JSON::valid() {

  return _valid;

}

bool JSON::parse_json_value() {

  int c;

  c = skip_to_token();

  if (c == -1) {

    return false;

  }

  // Must start with object or array

  if (level == 0) {

    switch (c) {

    case '{':

      if (parse_json_object() == false) {

        return false;

      }

      c = skip_to_token();

      if (c > 0) {

        mark_pos();

        error(SYNTAX_ERROR, "Only one top level object/array is allowed.");

        return false;

      } else if (c < 0) {

        return false;

      }

      return true;

    case '[':

      if (parse_json_array() == false) {

        return false;

      }

      c = skip_to_token();

      if (c > 0) {

        mark_pos();

        error(SYNTAX_ERROR, "Only one top level object/array is allowed.");

        return false;

      } else if (c < 0) {

        return false;

      }

      return true;

    case 0:

      error(SYNTAX_ERROR, "EOS was encountered before any json declarations");

      return false;

    default:

      error(SYNTAX_ERROR, "Json must start with an object or an array.");

      return false;

    }

  } else { // level > 0

    switch (c) {

    case '{':

      return parse_json_object();

    case '[':

      return parse_json_array();

    case '"':

      return parse_json_string();

    case '-': case '0':

    case '1': case '2': case '3':

    case '4': case '5': case '6':

    case '7': case '8': case '9':

      return parse_json_number();

    case 't':

      return parse_json_symbol("true", JSON_TRUE);

    case 'f':

      return parse_json_symbol("false", JSON_FALSE);

    case 'n':

      return parse_json_symbol("null", JSON_NULL);

    case 0:

      error(SYNTAX_ERROR, "EOS was encountered when expecting a json value.");

      return false;

    default:

      error(SYNTAX_ERROR, "Could not parse as a json value (did you forget to quote your strings?).");

      return false;

    }

  }

}

// Should only be called when we actually have the start of an object

// Otherwise it is an internal error

bool JSON::parse_json_object() {

  NOT_PRODUCT(const char* prev_pos);

  int c;

  mark_pos();

  // Check that we are not called in error

  if (expect_any("{", "object start", INTERNAL_ERROR) <= 0) {

    return false;

  }

  if (!callback(JSON_OBJECT_BEGIN, NULL, level++)) {

    return false;

  }

  for (;;) {

    mark_pos();

    c = skip_to_token();

    if (c == 0) {

      error(SYNTAX_ERROR, "EOS when expecting an object key or object end");

      return false;

    } else if (c < 0) {

      return false;

    } else if (c == '}') {

      // We got here from either empty object "{}" or ending comma "{a:1,}"

      next();

      break;

    }

    NOT_PRODUCT(prev_pos = pos);

    if (parse_json_key() == false) {

      return false;

    }

    assert(pos > prev_pos, "parsing stalled");

    skip_to_token();

    mark_pos();

    if (expect_any(":", "object key-value separator") <= 0) {

      return false;

    }

    skip_to_token();

    mark_pos();

    NOT_PRODUCT(prev_pos = pos);

    if (parse_json_value() == false) {

      return false;

    }

    assert(pos > prev_pos, "parsing stalled");

    c = skip_to_token();

    mark_pos();

    if (expect_any(",}", "value separator or object end") <= 0) {

      return false;

    }

    if (c == '}') {

      break;

    }

  }

  assert(c == '}', "array parsing ended without object end token ('}')");

  return callback(JSON_OBJECT_END, NULL, --level);

}

// Should only be called when we actually have the start of an array

// Otherwise it is an internal error

bool JSON::parse_json_array() {

  NOT_PRODUCT(const char* prev_pos);

  int c;

  mark_pos();

  // Check that we are not called in error

  if (expect_any("[", "array start character", INTERNAL_ERROR) <= 0) {

    return false;

  }

  if (!callback(JSON_ARRAY_BEGIN, NULL, level++)) {

    return false;

  }

  for (;;) {

    mark_pos();

    c = skip_to_token();

    if (c == 0) {

      error(SYNTAX_ERROR, "EOS when expecting a json value or array end");

      return false;

    } else if (c < 0) {

      return false;

    } else if (c == ']') {

      // We got here from either empty array "[]" or ending comma "[1,]"

      next();

      break;

    }

    mark_pos();

    NOT_PRODUCT(prev_pos = pos);

    if (parse_json_value() == false) {

      return false;

    }

    assert(pos > prev_pos, "parsing stalled");

    c = skip_to_token();

    mark_pos();

    if (expect_any(",]", "value separator or array end") <= 0) {

      return false;

    }

    if (c == ']') {

      break;

    }

  }

  assert(c == ']', "array parsing ended without array end token (']')");

  return callback(JSON_ARRAY_END, NULL, --level);

}

bool JSON::parse_json_string(bool key) {

  const char* end;

  JSON_VAL v;

  mark_pos();

  if (expect_any("\"", "string start character", INTERNAL_ERROR) <= 0) {

    return false;

  }

  end = strchr(pos, '"'); // TODO: escapes

  if (end == NULL) {

    error(SYNTAX_ERROR, "String started here never ended. Expected \'\"\' before EOS.");

    return false;

  }

  v.str.start = pos;

  v.str.length = end - pos;

  skip(end - pos);

  if (expect_any("\"", "string end character", INTERNAL_ERROR) <= 0) {

    return false;

  }

  if (key == true) {

    return callback(JSON_KEY, &v, level);

  } else {

    return callback(JSON_STRING, &v, level);

  }

}

// TODO: hotspot equivalents?

static bool is_alpha(u_char c) {

  return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z');

}

static bool is_numeric(u_char c) {

  return (c >= '0' && c <= '9');

}

static bool is_alnum(u_char c) {

  return is_alpha(c) || is_numeric(c);

}

static bool is_word(u_char c) {

  return c == '_' || is_alnum(c);

}

// Allow object keys to be without quotation,

// but then restrict to ([a-zA-Z0-9_])+

bool JSON::parse_json_key() {

  const char* begin;

  JSON_VAL v;

  u_char c;

  mark_pos();

  c = peek();

  if (c == '"') {

    return parse_json_string(true);

  }

  begin = pos;

  c = peek();

  if (c == 0) {

    error(SYNTAX_ERROR, "Got EOS when expecting an object key.");

    return false;

  } else if (is_word(c) == false) {

    error(SYNTAX_ERROR, "Expected an object key, which can be a double-quoted (\") string or a simple string (only alphanumeric characters and underscore, separated by whitespace) that doesn't need to be quoted.");

    return false;

  }

  for (;;) {

    c = peek();

    // Allow the key to be delimited by control characters and the object key-value separator ':'

    if (c <= ' ' || c == ':') {

      break;

    } else if (is_word(c) == false) {

      error(SYNTAX_ERROR, "Object key need to be quoted, or consist entirely of alphanumeric characters and underscores.");

      return false;

    }

    next();

  }

  v.str.start = begin;

  v.str.length = pos - begin;

  return callback(JSON_KEY, &v, level);

}

bool JSON::parse_json_number() {

  double double_value;

  int tokens, read;

  JSON_VAL v;

  mark_pos();

  // Parsing number - for simplicity ints are limited to 2**53

  // sscanf as a double and check if part is 0.

  tokens = sscanf(pos, "%lf%n", &double_value, &read);

  assert(tokens <= 1, "scanf implementation that counts as a token, parsing json numbers will always fail");

  if (tokens == 1) {

    assert(read > 0, "sanity");

    if (floor(double_value) == double_value) {

      // No exponent - treat as an int

      v.int_value = (int)double_value;

      if (!callback(JSON_NUMBER_INT, &v, level)) {

        return false;

      }

    } else {

      v.double_value = double_value;

      if (!callback(JSON_NUMBER_FLOAT, &v, level)) {

        return false;

      }

    }

    skip(read);

    return true;

  }

  error(SYNTAX_ERROR, "Couldn't parse json number (note that exponents are not supported).");

  return false;

}

bool JSON::parse_json_symbol(const char* name, JSON_TYPE symbol) {

  if (expect_string(name, "maybe you forgot to quote your strings?") == false) {

    mark_pos();

    return false;

  }

  return callback(symbol, NULL, level);

}

void JSON::mark_pos() {

  assert((mark == start || *(mark - 1)) != 0, "buffer overrun");

  assert(mark <= pos, "mark runahead");

  u_char c;

  while (mark < pos) {

    c = *mark;

    assert(c != 0, "pos buffer overrun?");

    if (c != 0) {

      mark++;

      column++;

    }

    if (c == '\n') {

      line++;

      column = 0;

    }

  }

  assert(mark <= pos, "mark runahead");

}

u_char JSON::next() {

  assert((pos == start || *(pos - 1)) != 0, "buffer overrun");

  u_char c = *pos;

  if (c != 0) {

    pos++;

  }

  return c;

}

u_char JSON::peek() {

  return *pos;

}

// Peek ahead i chars (0 is same as peek())

u_char JSON::peek(size_t i) {

  u_char c;

  const char* p;

  p = pos;

  c = *p;

  while (i > 0 && c != 0) {

    i--;

    p++;

    c = *p;

  }

  return c;

}

/*

 * Check that one of the expected characters is next in the stream.

 * If not, it is an error.

 * Returns 0 if EOS is encountered.

 * Returns -1 if the next character was not one of the expected.

 * Otherwise consumes and returns the expected character that was encountered.

 */

int JSON::expect_any(const char* valid_chars, const char* error_msg, JSON_ERROR e) {

  size_t len;

  u_char c;

  len = strlen(valid_chars);

  assert(len > 0, "need non-empty string");

  c = peek();

  if (c == 0) {

    error(e, "Got EOS when expecting %s (%s\'%s\').", error_msg, len > 1 ? "one of " : "", valid_chars);

    return 0;

  }

  for (size_t i = 0; i < len; i++) {

    if (c == valid_chars[i]) {

      return next();

    }

  }

  error(e, "Expected %s (%s\'%s\').", error_msg, len > 1 ? "one of " : "", valid_chars);

  return -1;

}

/*

 * Check that the expected string is next in the stream.

 * If not, it is an error.

 * Consumes the expected characters if they are present.

 * Returns true if the expected characters were present, otherwise false.

 */

bool JSON::expect_string(const char* expected_string, const char* error_msg, JSON_ERROR e) {

  u_char c, expected_char;

  size_t len;

  assert(expected_string != NULL, "need non-null string");

  len = strlen(expected_string);

  assert(len > 0, "need non-empty string");

  for (size_t i = 0; i < len; i++) {

    expected_char = expected_string[i];

    assert(expected_char > ' ', "not sane for control characters");

    if (expected_char <= ' ') {

      error(INTERNAL_ERROR, "expect got a control char");

    }

    c = pos[i];

    if (c == 0) {

      error(e, "EOS encountered when expecting %s (\"%s\")", error_msg, expected_string);

      return false;

    } else if (c != expected_char) {

      error(e, "Expected \"%s\" (%s)", expected_string, error_msg);

      return false;

    }

  }

  skip(len);

  return true;

}

/*

 * Skip i characters.

 * Returns number of characters skipped.

 */

size_t JSON::skip(size_t i) {

  u_char c;

  size_t j;

  c = peek();

  for (j = i; c != 0 && j > 0; j--) {

    c = next();

  }

  return i - j;

}

/*

 * Skip whitespace and comments.

 * Returns the first token after whitespace/comments without consuming it

 * Returns 0 if EOS is encountered.

 * Returns -1 if there is an error

 */

int JSON::skip_to_token() {

  for (;;) {

    int c = peek(0);

    if (c == '/') {

      u_char c2 = peek(1);

      if (c2 == '/') {