/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2014-2019 Damien P. George
 * Copyright (c) Quectel Wireless Solution, Co., Ltd.All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <stdio.h>

#include "py/objlist.h"
#include "py/objstringio.h"
#include "py/parsenum.h"
#include "py/runtime.h"
#include "py/stream.h"

#if MICROPY_PY_UJSON

STATIC mp_obj_t mod_ujson_dump(mp_obj_t obj, mp_obj_t stream) {
 mp_get_stream_raise(stream, MP_STREAM_OP_WRITE);
 mp_print_t print = {MP_OBJ_TO_PTR(stream), mp_stream_write_adaptor};
 mp_obj_print_helper(&print, obj, PRINT_JSON);
 return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_ujson_dump_obj, mod_ujson_dump);

STATIC mp_obj_t mod_ujson_dumps(mp_obj_t obj) {
 vstr_t vstr;
 mp_print_t print;
 vstr_init_print(&vstr, 8, &print);
 mp_obj_print_helper(&print, obj, PRINT_JSON);
 return mp_obj_new_str_from_vstr(&mp_type_str, &vstr);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_dumps_obj, mod_ujson_dumps);

// The function below implements a simple non-recursive JSON parser.
//
// The JSON specification is at http://www.ietf.org/rfc/rfc4627.txt
// The parser here will parse any valid JSON and return the correct
// corresponding Python object. It allows through a superset of JSON, since
// it treats commas and colons as "whitespace", and doesn't care if
// brackets/braces are correctly paired. It will raise a ValueError if the
// input is outside it's specs.
//
// Most of the work is parsing the primitives (null, false, true, numbers,
// strings). It does 1 pass over the input stream. It tries to be fast and
// small in code size, while not using more RAM than necessary.

typedef struct _ujson_stream_t {
 mp_obj_t stream_obj;
 mp_uint_t (*read)(mp_obj_t obj, void *buf, mp_uint_t size, int *errcode);
 int errcode;
 byte cur;
} ujson_stream_t;

#define S_EOF (0) // null is not allowed in json stream so is ok as EOF marker
#define S_END(s) ((s).cur == S_EOF)
#define S_CUR(s) ((s).cur)
#define S_NEXT(s) (ujson_stream_next(&(s)))

STATIC byte ujson_stream_next(ujson_stream_t *s) {
 mp_uint_t ret = s->read(s->stream_obj, &s->cur, 1, &s->errcode);
 if (s->errcode != 0) {
 mp_raise_OSError(s->errcode);
 }
 if (ret == 0) {
 s->cur = S_EOF;
 }
 return s->cur;
}

STATIC mp_obj_t mod_ujson_load(mp_obj_t stream_obj) {
 const mp_stream_p_t *stream_p = mp_get_stream_raise(stream_obj, MP_STREAM_OP_READ);
 ujson_stream_t s = {stream_obj, stream_p->read, 0, 0};
 vstr_t vstr;
 vstr_init(&vstr, 8);
 mp_obj_list_t stack; // we use a list as a simple stack for nested JSON
 stack.len = 0;
 stack.items = NULL;
 mp_obj_t stack_top = MP_OBJ_NULL;
 const mp_obj_type_t *stack_top_type = NULL;
 mp_obj_t stack_key = MP_OBJ_NULL;
 S_NEXT(s);
 for (;;) {
 cont:
 if (S_END(s)) {
 break;
 }
 mp_obj_t next = MP_OBJ_NULL;
 bool enter = false;
 byte cur = S_CUR(s);
 S_NEXT(s);
 switch (cur) {
 case ',':
 case ':':
 case ' ':
 case '\t':
 case '\n':
 case '\r':
 goto cont;
 case 'n':
 if (S_CUR(s) == 'u' && S_NEXT(s) == 'l' && S_NEXT(s) == 'l') {
 S_NEXT(s);
 next = mp_const_none;
 } else {
 goto fail;
 }
 break;
 case 'f':
 if (S_CUR(s) == 'a' && S_NEXT(s) == 'l' && S_NEXT(s) == 's' && S_NEXT(s) == 'e') {
 S_NEXT(s);
 next = mp_const_false;
 } else {
 goto fail;
 }
 break;
 case 't':
 if (S_CUR(s) == 'r' && S_NEXT(s) == 'u' && S_NEXT(s) == 'e') {
 S_NEXT(s);
 next = mp_const_true;
 } else {
 goto fail;
 }
 break;
 case '"':
 vstr_reset(&vstr);
 for (; !S_END(s) && S_CUR(s) != '"';) {
 byte c = S_CUR(s);
 if (c == '\\') {
 c = S_NEXT(s);
 switch (c) {
 case 'b':
 c = 0x08;
 break;
 case 'f':
 c = 0x0c;
 break;
 case 'n':
 c = 0x0a;
 break;
 case 'r':
 c = 0x0d;
 break;
 case 't':
 c = 0x09;
 break;
 case 'u': {
 mp_uint_t num = 0;
 for (int i = 0; i < 4; i++) {
 c = (S_NEXT(s) | 0x20) - '0';
 if (c > 9) {
 c -= ('a' - ('9' + 1));
 }
 num = (num << 4) | c;
 }
 vstr_add_char(&vstr, num);
 goto str_cont;
 }
 }
 }
 vstr_add_byte(&vstr, c);
 str_cont:
 S_NEXT(s);
 }
 if (S_END(s)) {
 goto fail;
 }
 S_NEXT(s);
 next = mp_obj_new_str(vstr.buf, vstr.len);
 break;
 case '-':
 case '0':
 case '1':
 case '2':
 case '3':
 case '4':
 case '5':
 case '6':
 case '7':
 case '8':
 case '9': {
 bool flt = false;
 vstr_reset(&vstr);
 for (;;) {
 vstr_add_byte(&vstr, cur);
 cur = S_CUR(s);
 if (cur == '.' || cur == 'E' || cur == 'e') {
 flt = true;
 } else if (cur == '+' || cur == '-' || unichar_isdigit(cur)) {
 // pass
 } else {
 break;
 }
 S_NEXT(s);
 }
 if (flt) {
 next = mp_parse_num_decimal(vstr.buf, vstr.len, false, false, NULL);
 } else {
 next = mp_parse_num_integer(vstr.buf, vstr.len, 10, NULL);
 }
 break;
 }
 case '[':
 next = mp_obj_new_list(0, NULL);
 enter = true;
 break;
 case '{':
 next = mp_obj_new_dict(0);
 enter = true;
 break;
 case '}':
 case ']': {
 if (stack_top == MP_OBJ_NULL) {
 // no object at all
 goto fail;
 }
 if (stack.len == 0) {
 // finished; compound object
 goto success;
 }
 stack.len -= 1;
 stack_top = stack.items[stack.len];
 stack_top_type = mp_obj_get_type(stack_top);
 goto cont;
 }
 default:
 goto fail;
 }
 if (stack_top == MP_OBJ_NULL) {
 stack_top = next;
 stack_top_type = mp_obj_get_type(stack_top);
 if (!enter) {
 // finished; single primitive only
 goto success;
 }
 } else {
 // append to list or dict
 if (stack_top_type == &mp_type_list) {
 mp_obj_list_append(stack_top, next);
 } else {
 if (stack_key == MP_OBJ_NULL) {
 stack_key = next;
 if (enter) {
 goto fail;
 }
 } else {
 mp_obj_dict_store(stack_top, stack_key, next);
 stack_key = MP_OBJ_NULL;
 }
 }
 if (enter) {
 if (stack.items == NULL) {
 mp_obj_list_init(&stack, 1);
 stack.items[0] = stack_top;
 } else {
 mp_obj_list_append(MP_OBJ_FROM_PTR(&stack), stack_top);
 }
 stack_top = next;
 stack_top_type = mp_obj_get_type(stack_top);
 }
 }
 }
success:
 // eat trailing whitespace
 while (unichar_isspace(S_CUR(s))) {
 S_NEXT(s);
 }
 if (!S_END(s)) {
 // unexpected chars
 goto fail;
 }
 if (stack_top == MP_OBJ_NULL || stack.len != 0) {
 // not exactly 1 object
 goto fail;
 }
 vstr_clear(&vstr);
 return stack_top;

fail:
 mp_raise_ValueError(MP_ERROR_TEXT("syntax error in JSON"));
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_load_obj, mod_ujson_load);

STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) {
 mp_buffer_info_t bufinfo;
 mp_get_buffer_raise(obj, &bufinfo, MP_BUFFER_READ);
 vstr_t vstr = {bufinfo.len, bufinfo.len, (char *)bufinfo.buf, true};
 mp_obj_stringio_t sio = {{&mp_type_stringio}, &vstr, 0, MP_OBJ_NULL};
 return mod_ujson_load(MP_OBJ_FROM_PTR(&sio));
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_ujson_loads_obj, mod_ujson_loads);

STATIC const mp_rom_map_elem_t mp_module_ujson_globals_table[] = {
 { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_ujson) },
 { MP_ROM_QSTR(MP_QSTR_dump), MP_ROM_PTR(&mod_ujson_dump_obj) },
 { MP_ROM_QSTR(MP_QSTR_dumps), MP_ROM_PTR(&mod_ujson_dumps_obj) },
 { MP_ROM_QSTR(MP_QSTR_load), MP_ROM_PTR(&mod_ujson_load_obj) },
 { MP_ROM_QSTR(MP_QSTR_loads), MP_ROM_PTR(&mod_ujson_loads_obj) },
};

STATIC MP_DEFINE_CONST_DICT(mp_module_ujson_globals, mp_module_ujson_globals_table);

const mp_obj_module_t mp_module_ujson = {
 .base = { &mp_type_module },
 .globals = (mp_obj_dict_t *)&mp_module_ujson_globals,
};

#endif // MICROPY_PY_UJSON