/* vim: set et ts=3 sw=3 sts=3 ft=c:
 *
 * Copyright (C) 2012, 2013, 2014 James McLaughlin et al.  All rights reserved.
 * https://github.com/udp/json-parser
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <glib.h>

#include "json.h"

#ifdef _MSC_VER
   #ifndef _CRT_SECURE_NO_WARNINGS
      #define _CRT_SECURE_NO_WARNINGS
   #endif
#endif

#ifdef __cplusplus
const struct _json_value json_value_none;    /* zero-d by ctor */
#else
const struct _json_value json_value_none = { 0 };
#endif

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <math.h>

typedef unsigned int json_uchar;

static unsigned char hex_value(json_char c)
{
	if (g_ascii_isdigit(c)) {
		return c - '0';
	}

	switch (c) {
	case 'a': case 'A': return 0x0A;
	case 'b': case 'B': return 0x0B;
	case 'c': case 'C': return 0x0C;
	case 'd': case 'D': return 0x0D;
	case 'e': case 'E': return 0x0E;
	case 'f': case 'F': return 0x0F;
	default: return 0xFF;
	}
}

typedef struct {
	unsigned long used_memory;

	unsigned int uint_max;
	unsigned long ulong_max;

	json_settings settings;
	int first_pass;

} json_state;

static void * default_alloc(size_t size, int zero, void * user_data)
{
	return zero ? calloc(1, size) : malloc(size);
}

static void default_free(void * ptr, void * user_data)
{
	free(ptr);
}

static void * json_alloc(json_state * state, unsigned long size, int zero)
{
	if ((state->ulong_max - state->used_memory) < size) {
		return 0;
	}

	if (state->settings.max_memory
	    && (state->used_memory += size) > state->settings.max_memory) {
		return 0;
	}

	return state->settings.mem_alloc(size, zero, state->settings.user_data);
}

static int new_value
        (json_state * state, json_value ** top, json_value ** root, json_value ** alloc, json_type type)
{
	json_value * value;
	int values_size;

	if (!state->first_pass) {
		value = *top = *alloc;
		*alloc = (*alloc)->_reserved.next_alloc;

		if (!*root) {
			*root = value;
		}

		switch (value->type) {
		case json_array:

			if (!(value->u.array.values = (json_value **) json_alloc
			                                      (state, value->u.array.length * sizeof(json_value *),
			                                      0))) {
				return 0;
			}

			value->u.array.length = 0;
			break;

		case json_object:

			values_size = sizeof(*value->u.object.values) * value->u.object.length;

			if (!((*(void **) &value->u.object.values) = json_alloc
			                                                     (state, values_size +
			                                                     ((unsigned long) value->u.object.values),
			                                                     0))) {
				return 0;
			}

			value->_reserved.object_mem = (*(char **) &value->u.object.values) + values_size;

			value->u.object.length = 0;
			break;

		case json_string:

			if (!(value->u.string.ptr = (json_char *) json_alloc
			                                    (state, (value->u.string.length + 1) * sizeof(json_char),
			                                    0))) {
				return 0;
			}

			value->u.string.length = 0;
			break;

		default:
			break;
		}
		;

		return 1;
	}

	value = (json_value *) json_alloc(state, sizeof(json_value), 1);

	if (!value) {
		return 0;
	}

	if (!*root) {
		*root = value;
	}

	value->type = type;
	value->parent = *top;

	if (*alloc) {
		(*alloc)->_reserved.next_alloc = value;
	}

	*alloc = *top = value;

	return 1;
}

#define e_off \
	((int) (i - cur_line_begin))

#define whitespace \
case '\n': ++cur_line;  cur_line_begin = i; \
case ' ': case '\t': case '\r'

#define string_add(b)  \
	do { if (!state.first_pass) { string [string_length] = b; } ++string_length; } while (0);

static const long
        flag_next             = 1 << 0,
        flag_reproc           = 1 << 1,
        flag_need_comma       = 1 << 2,
        flag_seek_value       = 1 << 3,
        flag_escaped          = 1 << 4,
        flag_string           = 1 << 5,
        flag_need_colon       = 1 << 6,
        flag_done             = 1 << 7,
        flag_num_negative     = 1 << 8,
        flag_num_zero         = 1 << 9,
        flag_num_e            = 1 << 10,
        flag_num_e_got_sign   = 1 << 11,
        flag_num_e_negative   = 1 << 12,
        flag_line_comment     = 1 << 13,
        flag_block_comment    = 1 << 14;

json_value * json_parse_ex(json_settings * settings,
                           const json_char * json,
                           size_t length,
                           char * error_buf)
{
	json_char error [json_error_max];
	unsigned int cur_line;
	const json_char * cur_line_begin, * i, * end;
	json_value * top, * root, * alloc = 0;
	json_state state = { 0 };
	long flags;
	long num_digits = 0, num_e = 0;
	json_int_t num_fraction = 0;

	/* Skip UTF-8 BOM
	 */
	if (length >= 3 && ((unsigned char) json [0]) == 0xEF
	    && ((unsigned char) json [1]) == 0xBB
	    && ((unsigned char) json [2]) == 0xBF) {
		json += 3;
		length -= 3;
	}

	error[0] = '\0';
	end = (json + length);

	memcpy(&state.settings, settings, sizeof(json_settings));

	if (!state.settings.mem_alloc) {
		state.settings.mem_alloc = default_alloc;
	}

	if (!state.settings.mem_free) {
		state.settings.mem_free = default_free;
	}

	memset(&state.uint_max, 0xFF, sizeof(state.uint_max));
	memset(&state.ulong_max, 0xFF, sizeof(state.ulong_max));

	state.uint_max -= 8; /* limit of how much can be added before next check */
	state.ulong_max -= 8;

	for (state.first_pass = 1; state.first_pass >= 0; --state.first_pass) {
		json_uchar uchar;
		unsigned char uc_b1, uc_b2, uc_b3, uc_b4;
		json_char * string = 0;
		unsigned int string_length = 0;

		top = root = 0;
		flags = flag_seek_value;

		cur_line = 1;
		cur_line_begin = json;

		for (i = json;; ++i) {
			json_char b = (i == end ? 0 : *i);

			if (flags & flag_string) {
				if (!b) {
					sprintf(error, "Unexpected EOF in string (at %d:%d)", cur_line, e_off);
					goto e_failed;
				}

				if (string_length > state.uint_max) {
					goto e_overflow;
				}

				if (flags & flag_escaped) {
					flags &= ~flag_escaped;

					switch (b) {
					case 'b':  string_add('\b');  break;
					case 'f':  string_add('\f');  break;
					case 'n':  string_add('\n');  break;
					case 'r':  string_add('\r');  break;
					case 't':  string_add('\t');  break;
					case 'u':

						if (end - i < 4 ||
						    (uc_b1 = hex_value(*++i)) == 0xFF || (uc_b2 = hex_value(*++i)) ==
						    0xFF
						    || (uc_b3 = hex_value(*++i)) == 0xFF || (uc_b4 = hex_value(*++i)) ==
						    0xFF) {
							sprintf(error, "Invalid character value `%c` (at %d:%d)", b,
							        cur_line, e_off);
							goto e_failed;
						}

						uc_b1 = (uc_b1 << 4) | uc_b2;
						uc_b2 = (uc_b3 << 4) | uc_b4;
						uchar = (uc_b1 << 8) | uc_b2;

						if ((uchar & 0xF800) == 0xD800) {
							json_uchar uchar2;

							if (end - i < 6 || (*++i) != '\\' || (*++i) != 'u' ||
							    (uc_b1 = hex_value(*++i)) == 0xFF ||
							    (uc_b2 = hex_value(*++i)) == 0xFF
							    || (uc_b3 = hex_value(*++i)) == 0xFF ||
							    (uc_b4 = hex_value(*++i)) == 0xFF) {
								sprintf(error,
								        "Invalid character value `%c` (at %d:%d)", b,
								        cur_line, e_off);
								goto e_failed;
							}

							uc_b1 = (uc_b1 << 4) | uc_b2;
							uc_b2 = (uc_b3 << 4) | uc_b4;
							uchar2 = (uc_b1 << 8) | uc_b2;

							uchar = 0x010000 | ((uchar & 0x3FF) << 10) | (uchar2 & 0x3FF);
						}

						if (sizeof(json_char) >= sizeof(json_uchar) || (uchar <= 0x7F)) {
							string_add((json_char) uchar);
							break;
						}

						if (uchar <= 0x7FF) {
							if (state.first_pass) {
								string_length += 2;
							} else {                    string [string_length++] = 0xC0 |
								                                               (uchar >>
								                                                6);
								                    string [string_length++] = 0x80 |
								                                               (uchar &
								                                                0x3F); }

							break;
						}

						if (uchar <= 0xFFFF) {
							if (state.first_pass) {
								string_length += 3;
							} else {                    string [string_length++] = 0xE0 |
								                                               (uchar >>
								                                                12);
								                    string [string_length++] = 0x80 |
								                                               ((uchar
								                                                 >> 6) &
								                                                0x3F);
								                    string [string_length++] = 0x80 |
								                                               (uchar &
								                                                0x3F); }

							break;
						}

						if (state.first_pass) {
							string_length += 4;
						} else {                string [string_length++] = 0xF0 | (uchar >> 18);
							                string [string_length++] = 0x80 |
							                                           ((uchar >>
							                                             12) & 0x3F);
							                string [string_length++] = 0x80 |
							                                           ((uchar >>
							                                             6) & 0x3F);
							                string [string_length++] = 0x80 |
							                                           (uchar & 0x3F); }

						break;

					default:
						string_add(b);
					}
					;

					continue;
				}

				if (b == '\\') {
					flags |= flag_escaped;
					continue;
				}

				if (b == '"') {
					if (!state.first_pass) {
						string [string_length] = 0;
					}

					flags &= ~flag_string;
					string = 0;

					switch (top->type) {
					case json_string:

						top->u.string.length = string_length;
						flags |= flag_next;

						break;

					case json_object:

						if (state.first_pass) {
							(*(json_char **) &top->u.object.values) += string_length + 1;
						} else {
							top->u.object.values [top->u.object.length].name
							        = (json_char *) top->_reserved.object_mem;

							top->u.object.values [top->u.object.length].name_length
							        = string_length;

							(*(json_char **) &top->_reserved.object_mem) += string_length +
							                                                1;
						}

						flags |= flag_seek_value | flag_need_colon;
						continue;

					default:
						break;
					}
					;
				} else {
					string_add(b);
					continue;
				}
			}

			if (state.settings.settings & json_enable_comments) {
				if (flags & (flag_line_comment | flag_block_comment)) {
					if (flags & flag_line_comment) {
						if (b == '\r' || b == '\n' || !b) {
							flags &= ~flag_line_comment;
							--i; /* so null can be reproc'd */
						}

						continue;
					}

					if (flags & flag_block_comment) {
						if (!b) {
							sprintf(error, "%d:%d: Unexpected EOF in block comment",
							        cur_line, e_off);
							goto e_failed;
						}

						if (b == '*' && i < (end - 1) && i [1] == '/') {
							flags &= ~flag_block_comment;
							++i; /* skip closing sequence */
						}

						continue;
					}
				} else if (b == '/') {
					if (!(flags & (flag_seek_value | flag_done)) && top->type != json_object) {
						sprintf(error, "%d:%d: Comment not allowed here", cur_line, e_off);
						goto e_failed;
					}

					if (++i == end) {
						sprintf(error, "%d:%d: EOF unexpected", cur_line, e_off);
						goto e_failed;
					}

					switch (b = *i) {
					case '/':
						flags |= flag_line_comment;
						continue;

					case '*':
						flags |= flag_block_comment;
						continue;

					default:
						sprintf(error, "%d:%d: Unexpected `%c` in comment opening sequence",
						        cur_line, e_off, b);
						goto e_failed;
					}
					;
				}
			}

			if (flags & flag_done) {
				if (!b) {
					break;
				}

				switch (b) {
whitespace:
					continue;

				default:
					sprintf(error, "%d:%d: Trailing garbage: `%c`", cur_line, e_off, b);
					goto e_failed;
				}
				;
			}

			if (flags & flag_seek_value) {
				switch (b) {
whitespace:
					continue;

				case ']':

					if (top && top->type == json_array) {
						flags = (flags & ~(flag_need_comma | flag_seek_value)) | flag_next;
					} else {              sprintf(error, "%d:%d: Unexpected ]", cur_line, e_off);
						              goto e_failed; }

					break;

				default:

					if (flags & flag_need_comma) {
						if (b == ',') {
							flags &= ~flag_need_comma;
							continue;
						} else { sprintf(error, "%d:%d: Expected , before %c", cur_line, e_off,
							         b);
							 goto e_failed; }
					}

					if (flags & flag_need_colon) {
						if (b == ':') {
							flags &= ~flag_need_colon;
							continue;
						} else { sprintf(error, "%d:%d: Expected : before %c", cur_line, e_off,
							         b);
							 goto e_failed; }
					}

					flags &= ~flag_seek_value;

					switch (b) {
					case '{':

						if (!new_value(&state, &top, &root, &alloc, json_object)) {
							goto e_alloc_failure;
						}

						continue;

					case '[':

						if (!new_value(&state, &top, &root, &alloc, json_array)) {
							goto e_alloc_failure;
						}

						flags |= flag_seek_value;
						continue;

					case '"':

						if (!new_value(&state, &top, &root, &alloc, json_string)) {
							goto e_alloc_failure;
						}

						flags |= flag_string;

						string = top->u.string.ptr;
						string_length = 0;

						continue;

					case 't':

						if ((end - i) < 3 || *(++i) != 'r' || *(++i) != 'u' || *(++i) != 'e') {
							goto e_unknown_value;
						}

						if (!new_value(&state, &top, &root, &alloc, json_boolean)) {
							goto e_alloc_failure;
						}

						top->u.boolean = 1;

						flags |= flag_next;
						break;

					case 'f':

						if ((end - i) < 4 || *(++i) != 'a' || *(++i) != 'l' || *(++i) != 's' ||
						    *(++i) != 'e') {
							goto e_unknown_value;
						}

						if (!new_value(&state, &top, &root, &alloc, json_boolean)) {
							goto e_alloc_failure;
						}

						flags |= flag_next;
						break;

					case 'n':

						if ((end - i) < 3 || *(++i) != 'u' || *(++i) != 'l' || *(++i) != 'l') {
							goto e_unknown_value;
						}

						if (!new_value(&state, &top, &root, &alloc, json_null)) {
							goto e_alloc_failure;
						}

						flags |= flag_next;
						break;

					default:

						if (g_ascii_isdigit(b) || b == '-') {
							if (!new_value(&state, &top, &root, &alloc, json_integer)) {
								goto e_alloc_failure;
							}

							if (!state.first_pass) {
								while (g_ascii_isdigit(b) || b == '+' || b == '-'
								       || b == 'e' || b == 'E' || b == '.') {
									if ((++i) == end) {
										b = 0;
										break;
									}

									b = *i;
								}

								flags |= flag_next | flag_reproc;
								break;
							}

							flags &= ~(flag_num_negative | flag_num_e |
							           flag_num_e_got_sign | flag_num_e_negative |
							           flag_num_zero);

							num_digits = 0;
							num_fraction = 0;
							num_e = 0;

							if (b != '-') {
								flags |= flag_reproc;
								break;
							}

							flags |= flag_num_negative;
							continue;
						} else { sprintf(error, "%d:%d: Unexpected %c when seeking value",
							         cur_line, e_off, b);
							 goto e_failed; }
					}
					;
				}
				;
			} else {
				switch (top->type) {
				case json_object:

					switch (b) {
whitespace:
						continue;

					case '"':

						if (flags & flag_need_comma) {
							sprintf(error, "%d:%d: Expected , before \"", cur_line, e_off);
							goto e_failed;
						}

						flags |= flag_string;

						string = (json_char *) top->_reserved.object_mem;
						string_length = 0;

						break;

					case '}':

						flags = (flags & ~flag_need_comma) | flag_next;
						break;

					case ',':

						if (flags & flag_need_comma) {
							flags &= ~flag_need_comma;
							break;
						}

					default:

						sprintf(error, "%d:%d: Unexpected `%c` in object", cur_line, e_off, b);
						goto e_failed;
					}
					;

					break;

				case json_integer:
				case json_double:

					if (g_ascii_isdigit(b)) {
						++num_digits;

						if (top->type == json_integer || flags & flag_num_e) {
							if (!(flags & flag_num_e)) {
								if (flags & flag_num_zero) {
									sprintf(error,
									        "%d:%d: Unexpected `0` before `%c`",
									        cur_line, e_off, b);
									goto e_failed;
								}

								if (num_digits == 1 && b == '0') {
									flags |= flag_num_zero;
								}
							} else {
								flags |= flag_num_e_got_sign;
								num_e = (num_e * 10) + (b - '0');
								continue;
							}

							top->u.integer = (top->u.integer * 10) + (b - '0');
							continue;
						}

						num_fraction = (num_fraction * 10) + (b - '0');
						continue;
					}

					if (b == '+' || b == '-') {
						if ((flags & flag_num_e) && !(flags & flag_num_e_got_sign)) {
							flags |= flag_num_e_got_sign;

							if (b == '-') {
								flags |= flag_num_e_negative;
							}

							continue;
						}
					} else if (b == '.' && top->type == json_integer) {
						if (!num_digits) {
							sprintf(error, "%d:%d: Expected digit before `.`", cur_line,
							        e_off);
							goto e_failed;
						}

						top->type = json_double;
						top->u.dbl = (double) top->u.integer;

						num_digits = 0;
						continue;
					}

					if (!(flags & flag_num_e)) {
						if (top->type == json_double) {
							if (!num_digits) {
								sprintf(error, "%d:%d: Expected digit after `.`",
								        cur_line, e_off);
								goto e_failed;
							}

							top->u.dbl += ((double) num_fraction) /
							              (pow(10, (double) num_digits));
						}

						if (b == 'e' || b == 'E') {
							flags |= flag_num_e;

							if (top->type == json_integer) {
								top->type = json_double;
								top->u.dbl = (double) top->u.integer;
							}

							num_digits = 0;
							flags &= ~flag_num_zero;

							continue;
						}
					} else {
						if (!num_digits) {
							sprintf(error, "%d:%d: Expected digit after `e`", cur_line,
							        e_off);
							goto e_failed;
						}

						top->u.dbl *=
						        pow(10,
						            (double) (flags & flag_num_e_negative ? -num_e : num_e));
					}

					if (flags & flag_num_negative) {
						if (top->type == json_integer) {
							top->u.integer = -top->u.integer;
						} else {
							top->u.dbl = -top->u.dbl;
						}
					}

					flags |= flag_next | flag_reproc;
					break;

				default:
					break;
				}
				;
			}

			if (flags & flag_reproc) {
				flags &= ~flag_reproc;
				--i;
			}

			if (flags & flag_next) {
				flags = (flags & ~flag_next) | flag_need_comma;

				if (!top->parent) {
					/* root value done */

					flags |= flag_done;
					continue;
				}

				if (top->parent->type == json_array) {
					flags |= flag_seek_value;
				}

				if (!state.first_pass) {
					json_value * parent = top->parent;

					switch (parent->type) {
					case json_object:

						parent->u.object.values
						[parent->u.object.length].value = top;

						break;

					case json_array:

						parent->u.array.values
						[parent->u.array.length] = top;

						break;

					default:
						break;
					}
					;
				}

				if ((++top->parent->u.array.length) > state.uint_max) {
					goto e_overflow;
				}

				top = top->parent;

				continue;
			}
		}

		alloc = root;
	}

	return root;

e_unknown_value:

	sprintf(error, "%d:%d: Unknown value", cur_line, e_off);
	goto e_failed;

e_alloc_failure:

	strcpy(error, "Memory allocation failure");
	goto e_failed;

e_overflow:

	sprintf(error, "%d:%d: Too long (caught overflow)", cur_line, e_off);
	goto e_failed;

e_failed:

	if (error_buf) {
		if (*error) {
			strcpy(error_buf, error);
		} else {
			strcpy(error_buf, "Unknown error");
		}
	}

	if (state.first_pass) {
		alloc = root;
	}

	while (alloc) {
		top = alloc->_reserved.next_alloc;
		state.settings.mem_free(alloc, state.settings.user_data);
		alloc = top;
	}

	if (!state.first_pass) {
		json_value_free_ex(&state.settings, root);
	}

	return 0;
}

json_value * json_parse(const json_char * json, size_t length)
{
	json_settings settings = { 0 };

	return json_parse_ex(&settings, json, length, 0);
}

void json_value_free_ex(json_settings * settings, json_value * value)
{
	json_value * cur_value;

	if (!value) {
		return;
	}

	value->parent = 0;

	while (value) {
		switch (value->type) {
		case json_array:

			if (!value->u.array.length) {
				settings->mem_free(value->u.array.values, settings->user_data);
				break;
			}

			value = value->u.array.values [--value->u.array.length];
			continue;

		case json_object:

			if (!value->u.object.length) {
				settings->mem_free(value->u.object.values, settings->user_data);
				break;
			}

			value = value->u.object.values [--value->u.object.length].value;
			continue;

		case json_string:

			settings->mem_free(value->u.string.ptr, settings->user_data);
			break;

		default:
			break;
		}
		;

		cur_value = value;
		value = value->parent;
		settings->mem_free(cur_value, settings->user_data);
	}
}

void json_value_free(json_value * value)
{
	json_settings settings = { 0 };

	settings.mem_free = default_free;
	json_value_free_ex(&settings, value);
}