/*
 * Copyright (C) 2012 Alex Iadicicco
 * Rights to this code are as documented in COPYING
 *
 * Structs and functions for interacting with JSON documents from C
 */

#include "mowgli.h"

/* TOC:
 * 0. JSON subsystem constants
 * 1. Reference counters
 * 2. Object creation and deletion
 * 3. Serializer (a.k.a. formatter, printer, etc.)
 * 4. Deserializer (a.k.a. parser, etc.)
 */

/*
 * 0. JSON SUBSYSTEM CONSTANTS
 */

#define LL_STACK_SIZE 128

#define JSON_REFCOUNT_CONSTANT -42

static mowgli_json_t json_null =
{
	.tag = MOWGLI_JSON_TAG_NULL,
	.refcount = JSON_REFCOUNT_CONSTANT,
};
mowgli_json_t *mowgli_json_null = &json_null;

static mowgli_json_t json_true =
{
	.tag = MOWGLI_JSON_TAG_BOOLEAN,
	.refcount = JSON_REFCOUNT_CONSTANT,
	{ .v_bool = true, }
};
mowgli_json_t *mowgli_json_true = &json_true;

static mowgli_json_t json_false =
{
	.tag = MOWGLI_JSON_TAG_BOOLEAN,
	.refcount = JSON_REFCOUNT_CONSTANT,
	{ .v_bool = false, }
};
mowgli_json_t *mowgli_json_false = &json_false;

static mowgli_json_t *json_alloc(mowgli_json_tag_t tag)
    MOWGLI_FATTR_MALLOC;

static void json_destroy(mowgli_json_t *n);
static void destroy_extra_string(mowgli_json_t *n);
static void destroy_extra_array(mowgli_json_t *n);
static void destroy_extra_object(mowgli_json_t *n);

typedef void (*destroy_extra_cb_t)(mowgli_json_t *);
static destroy_extra_cb_t destroy_extra[] =
{
	[MOWGLI_JSON_TAG_STRING] = destroy_extra_string,
	[MOWGLI_JSON_TAG_ARRAY] = destroy_extra_array,
	[MOWGLI_JSON_TAG_OBJECT] = destroy_extra_object,
};

/*
 * 1. REFERENCE COUNTERS
 */

mowgli_json_t *
mowgli_json_incref(mowgli_json_t *n)
{
	if ((n == NULL) || (n->refcount == JSON_REFCOUNT_CONSTANT))
		return n;

	n->refcount++;

	return n;
}

mowgli_json_t *
mowgli_json_decref(mowgli_json_t *n)
{
	if ((n == NULL) || (n->refcount == JSON_REFCOUNT_CONSTANT))
		return n;

	n->refcount--;

	if (n->refcount <= 0)
	{
		json_destroy(n);
		return NULL;
	}

	return n;
}

/* Debugging tool to recursively dump reference counts for an object
   and any children it may have.  This function will never be called
   outside of development, so is commented here.
   void dump_refs(mowgli_json_t *n)
   {
        char *s = "unk";
        mowgli_patricia_iteration_state_t st;

        switch (n->tag) {
        case MOWGLI_JSON_TAG_NULL: s = "null"; break;
        case MOWGLI_JSON_TAG_BOOLEAN: s = "boolean"; break;
        case MOWGLI_JSON_TAG_INTEGER: s = "integer"; break;
        case MOWGLI_JSON_TAG_FLOAT: s = "float"; break;
        case MOWGLI_JSON_TAG_STRING: s = "string"; break;
        case MOWGLI_JSON_TAG_ARRAY: s = "array"; break;
        case MOWGLI_JSON_TAG_OBJECT: s = "object"; break;
        }

        if (n->refcount == JSON_REFCOUNT_CONSTANT)
                printf("- %s\n", s);
        else
                printf("%d %s\n", n->refcount, s);

        if (n->tag == MOWGLI_JSON_TAG_ARRAY) {
                mowgli_node_t *cur;

                MOWGLI_LIST_FOREACH(cur, n->v_array->head) {
                        dump_refs(cur->data);
                }
        } else if (n->tag == MOWGLI_JSON_TAG_OBJECT) {
                mowgli_json_t *cur;

                mowgli_patricia_foreach_start(n->v_object, &st);
                while ((cur = mowgli_patricia_foreach_cur(n->v_object, &st)) != NULL) {
                        dump_refs(cur);
                        mowgli_patricia_foreach_next(n->v_object, &st);
                }
        }
   }
 */

/*
 * 2. OBJECT CREATION AND DELETION
 */

static mowgli_json_t *
json_alloc(mowgli_json_tag_t tag)
{
	mowgli_json_t *n;

	n = mowgli_alloc(sizeof *n);

	n->tag = tag;
	n->refcount = 0;

	return n;
}

static void
json_destroy(mowgli_json_t *n)
{
	return_if_fail(n != NULL);

	if (destroy_extra[n->tag] != NULL)
		destroy_extra[n->tag](n);

	mowgli_free(n);
}

mowgli_json_t *
mowgli_json_create_integer(int v_int)
{
	mowgli_json_t *n = json_alloc(MOWGLI_JSON_TAG_INTEGER);

	n->v.v_int = v_int;
	return n;
}

mowgli_json_t *
mowgli_json_create_float(double v_float)
{
	mowgli_json_t *n = json_alloc(MOWGLI_JSON_TAG_FLOAT);

	n->v.v_float = v_float;
	return n;
}

mowgli_json_t *
mowgli_json_create_string_n(const char *str, size_t len)
{
	mowgli_json_t *n = json_alloc(MOWGLI_JSON_TAG_STRING);

	n->v.v_string = mowgli_string_create();
	mowgli_string_append(n->v.v_string, str, len);

	return n;
}

mowgli_json_t *
mowgli_json_create_string(const char *str)
{
	return mowgli_json_create_string_n(str, strlen(str));
}

static void
destroy_extra_string(mowgli_json_t *n)
{
	mowgli_string_destroy(n->v.v_string);
}

mowgli_json_t *
mowgli_json_create_array(void)
{
	mowgli_json_t *n = json_alloc(MOWGLI_JSON_TAG_ARRAY);

	n->v.v_array = mowgli_list_create();
	return n;
}

static void
destroy_extra_array(mowgli_json_t *n)
{
	mowgli_node_t *cur, *next;

	MOWGLI_LIST_FOREACH_SAFE(cur, next, n->v.v_array->head)
	{
		mowgli_json_decref((mowgli_json_t *) cur->data);
		mowgli_node_delete(cur, n->v.v_array);
	}

	mowgli_list_free(n->v.v_array);
}

mowgli_json_t *
mowgli_json_create_object(void)
{
	mowgli_json_t *n = json_alloc(MOWGLI_JSON_TAG_OBJECT);

	n->v.v_object = mowgli_patricia_create(NULL);
	return n;
}

static void
destroy_extra_object_cb(const char *key, void *data, void *privdata)
{
	mowgli_json_decref((mowgli_json_t *) data);
}

static void
destroy_extra_object(mowgli_json_t *n)
{
	mowgli_patricia_destroy(n->v.v_object, destroy_extra_object_cb, NULL);
}

/*
 * 3. SERIALIZER (A.K.A. FORMATTER, PRINTER, ETC.)
 */

#define TAB_STRING "    "
#define TAB_LEN 4

static void
serialize_pretty_indent(mowgli_json_output_t *out, int pretty)
{
	int i;

	for (i = 0; i < pretty; i++)
		out->append(out, TAB_STRING, TAB_LEN);
}

static void
serialize_pretty_break(mowgli_json_output_t *out, int pretty)
{
	if (pretty < 1)
		return;

	out->append_char(out, '\n');
}

static int
serialize_pretty_increment(int pretty)
{
	return pretty > 0 ? pretty + 1 : 0;
}

static void
serialize_boolean(mowgli_json_t *n, mowgli_json_output_t *out, int pretty)
{
	if (n->v.v_bool)
		out->append(out, "true", 4);
	else
		out->append(out, "false", 5);
}

static void
serialize_int(mowgli_json_t *n, mowgli_json_output_t *out, int pretty)
{
	char buf[32];
	size_t len;

	len = snprintf(buf, 32, "%d", n->v.v_int);
	out->append(out, buf, len);
}

static void
serialize_float(mowgli_json_t *n, mowgli_json_output_t *out, int pretty)
{
	char buf[32];
	size_t len;

	len = snprintf(buf, 32, "%g", n->v.v_float);
	out->append(out, buf, len);
}

static const char *serialize_hex_digits = "0123456789abcdef";
static const char *serialize_escape = "\"\\\b\f\n\r\t";
static void
serialize_string_data(const char *p, size_t len, mowgli_json_output_t *out)
{
	unsigned i;
	unsigned char c;

	out->append_char(out, '"');

	for (i = 0; i < len; i++)
	{
		c = p[i];

		if (strchr(serialize_escape, c))
		{
			out->append_char(out, '\\');

			switch (c)
			{
			case '"': out->append_char(out, '"'); break;
			case '\\': out->append_char(out, '\\'); break;

			// case '/': out->append_char(out, '/'); break;
			case '\b': out->append_char(out, 'b'); break;
			case '\f': out->append_char(out, 'f'); break;
			case '\n': out->append_char(out, 'n'); break;
			case '\r': out->append_char(out, 'r'); break;
			case '\t': out->append_char(out, 't'); break;
			default:// hurrr
				out->append_char(out, c);
			}
		}
		else if ((c < 0x20) || (c > 0x7f))
		{
			out->append_char(out, '\\');

			/* XXX: \u output does not do UTF-8 */
			out->append_char(out, 'u');
			out->append_char(out, '0');
			out->append_char(out, '0');
			out->append_char(out, serialize_hex_digits[(c >> 4) & 0xf]);
			out->append_char(out, serialize_hex_digits[(c >> 0) & 0xf]);
		}
		else
		{
			out->append_char(out, c);
		}
	}

	out->append_char(out, '"');
}

static void
serialize_string(mowgli_json_t *n, mowgli_json_output_t *out, int pretty)
{
	serialize_string_data(n->v.v_string->str, n->v.v_string->pos, out);
}

static void
serialize_array(mowgli_json_t *n, mowgli_json_output_t *out, int pretty)
{
	mowgli_node_t *cur;

	out->append_char(out, '[');
	serialize_pretty_break(out, pretty);

	MOWGLI_LIST_FOREACH(cur, n->v.v_array->head)
	{
		serialize_pretty_indent(out, pretty);
		mowgli_json_serialize(cur->data, out, serialize_pretty_increment(pretty));

		if (cur->next != NULL)
			out->append_char(out, ',');

		serialize_pretty_break(out, pretty);
	}

	serialize_pretty_indent(out, pretty - 1);
	out->append_char(out, ']');
}

struct serialize_object_priv	/* lol, this is bullshit */
{
	int pretty;
	int remaining;
	mowgli_json_output_t *out;
};

static int
serialize_object_cb(const char *key, void *data, void *privdata)
{
	struct serialize_object_priv *priv = privdata;

	priv->remaining--;

	serialize_pretty_indent(priv->out, priv->pretty);

	serialize_string_data(key, strlen(key), priv->out);
	priv->out->append_char(priv->out, ':');

	if (priv->pretty)
		priv->out->append_char(priv->out, ' ');

	mowgli_json_serialize(data, priv->out,
			      serialize_pretty_increment(priv->pretty));

	if (priv->remaining)
		priv->out->append_char(priv->out, ',');

	serialize_pretty_break(priv->out, priv->pretty);

	return 0;
}

static void
serialize_object(mowgli_json_t *n, mowgli_json_output_t *out, int pretty)
{
	struct serialize_object_priv priv;

	out->append_char(out, '{');
	serialize_pretty_break(out, pretty);

	priv.pretty = pretty;
	priv.remaining = mowgli_patricia_size(n->v.v_object);
	priv.out = out;
	mowgli_patricia_foreach(n->v.v_object, serialize_object_cb, &priv);

	serialize_pretty_indent(out, pretty - 1);
	out->append_char(out, '}');
}

typedef void (*serializer_t)(mowgli_json_t *, mowgli_json_output_t *, int);
static serializer_t serializers[] =
{
	[MOWGLI_JSON_TAG_BOOLEAN] = serialize_boolean,
	[MOWGLI_JSON_TAG_INTEGER] = serialize_int,
	[MOWGLI_JSON_TAG_FLOAT] = serialize_float,
	[MOWGLI_JSON_TAG_STRING] = serialize_string,
	[MOWGLI_JSON_TAG_ARRAY] = serialize_array,
	[MOWGLI_JSON_TAG_OBJECT] = serialize_object,
};

void
mowgli_json_serialize(mowgli_json_t *n, mowgli_json_output_t *out, int pretty)
{
	if (n && serializers[n->tag])
		serializers[n->tag](n, out, pretty);
	else
		out->append(out, "null", 4);
}

static void
to_string_append(mowgli_json_output_t *out, const char *str, size_t len)
{
	mowgli_string_append(out->priv, str, len);
}

static void
to_string_append_char(mowgli_json_output_t *out, const char c)
{
	mowgli_string_append_char(out->priv, c);
}

void
mowgli_json_serialize_to_string(mowgli_json_t *n, mowgli_string_t *str, int pretty)
{
	mowgli_json_output_t out;

	out.append = to_string_append;
	out.append_char = to_string_append_char;
	out.priv = str;

	mowgli_json_serialize(n, &out, pretty);
}

/*
 * 4. DESERIALIZER (A.K.A. PARSER, ETC.)
 */

/* LL(1) parser format:

   Terminal symbols: { } [ ] : , STR NUM ID

   Rule table:
       0. [invalid]

       1. <json-document> := <object>
       2. <json-document> := <array>

       3.         <value> := <object>
       4.         <value> := <array>
       5.         <value> := STR
       6.         <value> := NUM
       7.         <value> := ID

       8.        <object> := { <obj-body>
       9.      <obj-body> := }
      10.      <obj-body> := <obj-elems>
      11.     <obj-elems> := <obj-elem> <obj-tail>
      12.      <obj-tail> := , <obj-elems>
      13.      <obj-tail> := }
      14.      <obj-elem> := STR : <value>

      15.         <array> := [ <arr-body>
      16.      <arr-body> := ]
      17.      <arr-body> := <arr-elems>
      18.     <arr-elems> := <value> <arr-tail>
      19.      <arr-tail> := , <arr-elems>
      20.      <arr-tail> := ]

   Transition table:
                   {    }    [    ]    :    ,  STR  NUM   ID
                 ---  ---  ---  ---  ---  ---  ---  ---  ---
   json-document   1         2
           value   3         4                   5    6    7
          object   8
        obj-body        9                       10
       obj-elems                                11
        obj-tail       13                  12
        obj-elem                                14
           array            15
        arr-body  17        17   16             17   17   17
       arr-elems  18        18                  18   18   18
        arr-tail                 20        19

   These two tables are effectively a program for an LL(1) parser. The
   hard work has been done. The remaining steps are to attach appropriate
   actions to the rules above, and to implement the LL(1) parsing
   algorithm.
 */

enum ll_sym
{
	SYM_NONE,

	TS_BEGIN_OBJECT,/* { */
	TS_END_OBJECT,	/* } */
	TS_BEGIN_ARRAY,	/* [ */
	TS_END_ARRAY,	/* ] */
	TS_NAME_SEP,	/* : */
	TS_VALUE_SEP,	/* , */
	TS_STRING,
	TS_NUMBER,
	TS_IDENTIFIER,

	NTS_JSON_DOCUMENT,
	NTS_VALUE,
	NTS_OBJECT,
	NTS_OBJ_BODY,
	NTS_OBJ_ELEMS,
	NTS_OBJ_TAIL,
	NTS_OBJ_ELEM,
	NTS_ARRAY,
	NTS_ARR_BODY,
	NTS_ARR_ELEMS,
	NTS_ARR_TAIL,

	SYM_COUNT
};

struct ll_token
{
	enum ll_sym sym;

	mowgli_json_t *val;
};

#define ERRBUFSIZE 128

/* typedef'd to mowgli_json_parse_t in json.h */
struct _mowgli_json_parse_t
{
	/* output queue */
	mowgli_list_t *out;

	/* error buffer */
	char error[ERRBUFSIZE];

	/* parser */
	bool multidoc;
	mowgli_list_t *build;
	enum ll_sym stack[LL_STACK_SIZE];

	unsigned top;

	/* lexer */
	mowgli_string_t *buf;
	enum
	{
		LEX_LIMBO,
		LEX_STRING,
		LEX_STRING_ESC,
		LEX_STRING_ESC_U,
		LEX_NUMBER,
		LEX_IDENTIFIER
	} lex;

	unsigned lex_u;
};

typedef void ll_action_t (mowgli_json_parse_t *, struct ll_token *tok);

/* Human-readable versions of symbols used in errors, etc. */
static char *ll_sym_name[] =
{
	[SYM_NONE] = "(none)",

	[TS_BEGIN_OBJECT] = "'{'",
	[TS_END_OBJECT] = "'}'",
	[TS_BEGIN_ARRAY] = "'['",
	[TS_END_ARRAY] = "']'",
	[TS_NAME_SEP] = "':'",
	[TS_VALUE_SEP] = "','",
	[TS_STRING] = "string",
	[TS_NUMBER] = "number",
	[TS_IDENTIFIER] = "identifier",

	[NTS_JSON_DOCUMENT] = "json-document",
	[NTS_VALUE] = "value",
	[NTS_OBJECT] = "object",
	[NTS_OBJ_BODY] = "object body",
	[NTS_OBJ_ELEMS] = "object elements",
	[NTS_OBJ_TAIL] = "object tail",
	[NTS_OBJ_ELEM] = "object element",

	[NTS_ARRAY] = "array",
	[NTS_ARR_BODY] = "array body",
	[NTS_ARR_ELEMS] = "array elements",
	[NTS_ARR_TAIL] = "array tail",

	[SYM_COUNT] = "(none)",
};

/* The LL(1) parser table. Uglier than it could have been, unfortunately */
static unsigned char ll_table[SYM_COUNT][SYM_COUNT] =
{
	[NTS_JSON_DOCUMENT] =
	{
		[TS_BEGIN_OBJECT] = 1,
		[TS_BEGIN_ARRAY] = 2,
	},

	[NTS_VALUE] =
	{
		[TS_BEGIN_OBJECT] = 3,
		[TS_BEGIN_ARRAY] = 4,
		[TS_STRING] = 5,
		[TS_NUMBER] = 6,
		[TS_IDENTIFIER] = 7,
	},

	[NTS_OBJECT] =
	{
		[TS_BEGIN_OBJECT] = 8,
	},
	[NTS_OBJ_BODY] =
	{
		[TS_END_OBJECT] = 9,
		[TS_STRING] = 10,
	},
	[NTS_OBJ_ELEMS] =
	{
		[TS_STRING] = 11,
	},
	[NTS_OBJ_TAIL] =
	{
		[TS_END_OBJECT] = 13,
		[TS_VALUE_SEP] = 12,
	},
	[NTS_OBJ_ELEM] =
	{
		[TS_STRING] = 14,
	},

	[NTS_ARRAY] =
	{
		[TS_BEGIN_ARRAY] = 15,
	},
	[NTS_ARR_BODY] =
	{
		[TS_BEGIN_OBJECT] = 17,
		[TS_BEGIN_ARRAY] = 17,
		[TS_END_ARRAY] = 16,
		[TS_STRING] = 17,
		[TS_NUMBER] = 17,
		[TS_IDENTIFIER] = 17,
	},
	[NTS_ARR_ELEMS] =
	{
		[TS_BEGIN_OBJECT] = 18,
		[TS_BEGIN_ARRAY] = 18,
		[TS_STRING] = 18,
		[TS_NUMBER] = 18,
		[TS_IDENTIFIER] = 18,
	},
	[NTS_ARR_TAIL] =
	{
		[TS_END_ARRAY] = 20,
		[TS_VALUE_SEP] = 19,
	},
};

/* The LL(1) rule table */
static enum ll_sym ll_rules[][3] =
{
	{ 0 },	/* 0 */

	{ NTS_OBJECT },
	{ NTS_ARRAY },

	{ NTS_OBJECT },
	{ NTS_ARRAY },
	{ TS_STRING },	/* 5 */
	{ TS_NUMBER },
	{ TS_IDENTIFIER },

	{ TS_BEGIN_OBJECT, NTS_OBJ_BODY },
	{ TS_END_OBJECT },
	{ NTS_OBJ_ELEMS },	/* 10 */
	{ NTS_OBJ_ELEM, NTS_OBJ_TAIL },
	{ TS_VALUE_SEP, NTS_OBJ_ELEMS },
	{ TS_END_OBJECT },
	{ TS_STRING, TS_NAME_SEP, NTS_VALUE },

	{ TS_BEGIN_ARRAY, NTS_ARR_BODY },	/* 15 */
	{ TS_END_ARRAY },
	{ NTS_ARR_ELEMS },
	{ NTS_VALUE, NTS_ARR_TAIL },
	{ TS_VALUE_SEP, NTS_ARR_ELEMS },
	{ TS_END_ARRAY },	/* 20 */
};

static struct ll_token *
ll_token_alloc(enum ll_sym sym, mowgli_json_t *val)
{
	struct ll_token *tok;

	tok = mowgli_alloc(sizeof *tok);
	tok->sym = sym;
	tok->val = val;

	return tok;
}

static void
ll_token_free(struct ll_token *tok)
{
	mowgli_json_decref(tok->val);
	mowgli_free(tok);
}

static bool
parse_out_empty(mowgli_json_parse_t *parse)
{
	return MOWGLI_LIST_LENGTH(parse->out) == 0;
}

static void
parse_out_enqueue(mowgli_json_parse_t *parse, mowgli_json_t *val)
{
	mowgli_node_add(val, mowgli_node_create(), parse->out);
}

static mowgli_json_t *
parse_out_dequeue(mowgli_json_parse_t *parse)
{
	mowgli_json_t *n;
	mowgli_node_t *head;

	if (MOWGLI_LIST_LENGTH(parse->out) == 0)
		return NULL;

	head = parse->out->head;

	if (head == NULL)
		return NULL;

	n = head->data;
	mowgli_node_delete(head, parse->out);
	mowgli_node_free(head);

	return n;
}

static void MOWGLI_FATTR_PRINTF(2, 3)
parse_error(mowgli_json_parse_t *parse, const char *fmt, ...)
{
	va_list va;

	va_start(va, fmt);
	vsnprintf(parse->error, ERRBUFSIZE, fmt, va);
	va_end(va);

	/* TODO: shut down everything, yadda yadda */
}

static void
ll_build_push(mowgli_json_parse_t *parse, mowgli_json_t *val)
{
	mowgli_node_add_head(val, mowgli_node_create(), parse->build);
}

static mowgli_json_t *
ll_build_pop(mowgli_json_parse_t *parse)
{
	mowgli_json_t *n;
	mowgli_node_t *head;

	if (MOWGLI_LIST_LENGTH(parse->build) == 0)
		return NULL;

	head = parse->build->head;

	if (head == NULL)	/* shouldn't happen... */
		return NULL;

	n = head->data;
	mowgli_node_delete(head, parse->build);
	mowgli_node_free(head);

	return n;
}

static mowgli_json_t obj_start_marker =
{
	.refcount = JSON_REFCOUNT_CONSTANT,
};
static mowgli_json_t arr_start_marker =
{
	.refcount = JSON_REFCOUNT_CONSTANT,
};

static void
ll_act_echo(mowgli_json_parse_t *parse, struct ll_token *tok)
{
	ll_build_push(parse, mowgli_json_incref(tok->val));
}

static void
ll_act_obj_start(mowgli_json_parse_t *parse, struct ll_token *tok)
{
	ll_build_push(parse, &obj_start_marker);
}

static void
ll_act_obj_end(mowgli_json_parse_t *parse, struct ll_token *tok)
{
	mowgli_json_t *obj;
	mowgli_json_t *key, *val;

	obj = mowgli_json_incref(mowgli_json_create_object());

	for (;;)
	{
		val = ll_build_pop(parse);

		if (val == &obj_start_marker)
			break;

		key = ll_build_pop(parse);

		if (key == &obj_start_marker)
			break;	/* should never happen, but in case */

		if (MOWGLI_JSON_TAG(key) != MOWGLI_JSON_TAG_STRING)
			break;	/* should also never happen */

		mowgli_json_object_add(obj, MOWGLI_JSON_STRING_STR(key), val);
		mowgli_json_decref(key);
		mowgli_json_decref(val);
	}

	ll_build_push(parse, obj);
}

static void
ll_act_arr_start(mowgli_json_parse_t *parse, struct ll_token *tok)
{
	ll_build_push(parse, &arr_start_marker);
}

static void
ll_act_arr_end(mowgli_json_parse_t *parse, struct ll_token *tok)
{
	mowgli_json_t *arr;
	mowgli_json_t *val;

	arr = mowgli_json_incref(mowgli_json_create_array());

	for (;;)
	{
		val = ll_build_pop(parse);

		if (val == &arr_start_marker)
			break;

		mowgli_json_array_add_head(arr, val);
		mowgli_json_decref(val);
	}

	ll_build_push(parse, arr);
}

static ll_action_t *ll_action[] =
{
	NULL,	/* 0 */

	NULL,
	NULL,

	NULL,
	NULL,
	ll_act_echo,	/* 5 */
	ll_act_echo,
	ll_act_echo,

	ll_act_obj_start,
	ll_act_obj_end,
	NULL,	/* 10 */
	NULL,
	NULL,
	ll_act_obj_end,
	ll_act_echo,

	ll_act_arr_start,	/* 15 */
	ll_act_arr_end,
	NULL,
	NULL,
	NULL,
	ll_act_arr_end,	/* 20 */
};

static void
ll_push(mowgli_json_parse_t *parse, enum ll_sym sym)
{
	parse->stack[parse->top++] = sym;
}

static enum ll_sym
ll_pop(mowgli_json_parse_t *parse)
{
	if (parse->top <= 0)
		return SYM_NONE;

	return parse->stack[--parse->top];
}

static bool
ll_stack_empty(mowgli_json_parse_t *parse)
{
	return parse->top == 0;
}

static void
ll_cycle(mowgli_json_parse_t *parse)
{
	mowgli_json_t *n;

	n = ll_build_pop(parse);

	if (n != NULL)
		parse_out_enqueue(parse, n);

	if (parse->multidoc)
		ll_push(parse, NTS_JSON_DOCUMENT);
}

static void
ll_parse(mowgli_json_parse_t *parse, struct ll_token *tok)
{
	enum ll_sym top, sym;

	int rule, i;

	for (;;)
	{
		if (ll_stack_empty(parse))
		{
			parse_error(parse, "Unexpected %s after JSON input", ll_sym_name[tok->sym]);
			break;
		}

		top = ll_pop(parse);

		if (top == tok->sym)
		{
			/* perfect! */

			if (ll_stack_empty(parse))
				ll_cycle(parse);

			break;
		}

		rule = ll_table[top][tok->sym];

		if (rule == 0)
		{
			parse_error(parse, "Expected %s, got %s", ll_sym_name[top],
				    ll_sym_name[tok->sym]);
			break;
		}

		if (ll_action[rule] != NULL)
			ll_action[rule](parse, tok);

		for (i = 2; i >= 0; i--)
		{
			sym = ll_rules[rule][i];

			if (sym != SYM_NONE)
				ll_push(parse, sym);
		}
	}

	ll_token_free(tok);
}

static void
lex_easy(mowgli_json_parse_t *parse, enum ll_sym sym)
{
	ll_parse(parse, ll_token_alloc(sym, NULL));
}

static void
lex_append(mowgli_json_parse_t *parse, char c)
{
	mowgli_string_append_char(parse->buf, c);
}

static mowgli_json_t *
lex_string_scan(char *s, size_t n)
{
	mowgli_json_t *val;
	mowgli_string_t *str;
	char ubuf[5];
	char *end = s + n;

	val = mowgli_json_incref(mowgli_json_create_string(""));
	str = val->v.v_string;

	ubuf[4] = '\0';	/* always */

	while (s < end)
	{
		if (*s == '\\')
		{
			/* Should this be moved to a separate function? */
			s++;

			switch (*s)
			{
			case '\"':
			case '\\':
			case '/':
				mowgli_string_append_char(str, *s);
				break;

			case 'b': mowgli_string_append_char(str, 0x8); break;
			case 'f': mowgli_string_append_char(str, 0xc); break;
			case 'n': mowgli_string_append_char(str, 0xa); break;
			case 'r': mowgli_string_append_char(str, 0xd); break;
			case 't': mowgli_string_append_char(str, 0x9); break;

			/* XXX: this is not the right way to parse \u */
			case 'u':
				s++;

				if (end - s < 4)
				{
					/* error */
				}
				else
				{
					memcpy(ubuf, s, 4);
					mowgli_string_append_char(str, strtol(ubuf, NULL, 16) & 0xff);
				}

				s += 3;	/* +3 points to last char */
				break;

			default:/* aww */
				break;
			}
		}
		else
		{
			mowgli_string_append_char(str, *s);
		}

		s++;
	}

	return val;
}

static void
lex_tokenize(mowgli_json_parse_t *parse)
{
	char *s = parse->buf->str;
	size_t n = parse->buf->pos;
	enum ll_sym sym = SYM_NONE;
	mowgli_json_t *val = NULL;

	switch (parse->lex)
	{
	case LEX_STRING:
		sym = TS_STRING;
		val = lex_string_scan(s, n);
		break;

	case LEX_NUMBER:

		if (strchr(s, '.') || strchr(s, 'e'))
			val = mowgli_json_incref(mowgli_json_create_float(strtod(s, NULL)));

		else
			val = mowgli_json_incref(mowgli_json_create_integer(strtol(s, NULL, 0)));

		sym = TS_NUMBER;
		break;

	case LEX_IDENTIFIER:
		sym = TS_IDENTIFIER;

		if (!strcmp(s, "null"))
			val = mowgli_json_null;

		else if (!strcmp(s, "true"))
			val = mowgli_json_true;

		else if (!strcmp(s, "false"))
			val = mowgli_json_false;

		else
			val = mowgli_json_null;

		/* error condition! */

		break;

	default:

		/* we should not be tokenizing here! */
		break;
	}

	mowgli_string_reset(parse->buf);
	parse->lex = LEX_LIMBO;

	ll_parse(parse, ll_token_alloc(sym, val));
}

/* lex_char returns true if it wants the char to be sent through again */
static bool
lex_char(mowgli_json_parse_t *parse, char c)
{
	switch (parse->lex)
	{
	case LEX_LIMBO:

		/* the easy ones */
		switch (c)
		{
		case '{': lex_easy(parse, TS_BEGIN_OBJECT); return false;
		case '}': lex_easy(parse, TS_END_OBJECT); return false;
		case '[': lex_easy(parse, TS_BEGIN_ARRAY); return false;
		case ']': lex_easy(parse, TS_END_ARRAY); return false;
		case ':': lex_easy(parse, TS_NAME_SEP); return false;
		case ',': lex_easy(parse, TS_VALUE_SEP); return false;
		}

		if ((c == '-') || (c == '.') || isdigit((unsigned char)c))
		{
			parse->lex = LEX_NUMBER;
			return true;
		}
		else if (isalpha((unsigned char)c))
		{
			parse->lex = LEX_IDENTIFIER;
			return true;
		}
		else if (c == '"')
		{
			parse->lex = LEX_STRING;
			return false;
		}
		else if (isspace((unsigned char)c))
		{
			return false;
		}

		parse_error(parse, "Cannot process character '%c' in input stream", c);

		return false;

	case LEX_STRING:

		if (c == '\\')
		{
			lex_append(parse, c);
			parse->lex = LEX_STRING_ESC;
		}
		else if (c == '"')
		{
			lex_tokenize(parse);
		}
		else
		{
			lex_append(parse, c);
		}

		return false;

	case LEX_STRING_ESC:
		lex_append(parse, c);

		if (c == 'u')
		{
			parse->lex_u = 0;
			parse->lex = LEX_STRING_ESC_U;
		}
		else
		{
			parse->lex = LEX_STRING;
		}

		return false;

	case LEX_STRING_ESC_U:
		lex_append(parse, c);

		parse->lex_u++;

		if (parse->lex_u >= 4)
			parse->lex = LEX_STRING;

		return false;

	case LEX_NUMBER:

		if ((c == '-') || (c == '.') || isdigit((unsigned char)c) || (toupper((unsigned char)c) == 'E'))
		{
			lex_append(parse, c);
			return false;
		}
		else
		{
			lex_tokenize(parse);
			return true;
		}

	case LEX_IDENTIFIER:

		if (isalpha((unsigned char)c))
		{
			lex_append(parse, c);
			return false;
		}
		else
		{
			lex_tokenize(parse);
			return true;
		}
	}

	/* This should never happen... */
	parse->lex = LEX_LIMBO;
	return false;
}

mowgli_json_parse_t *
mowgli_json_parse_create(bool multidoc)
{
	mowgli_json_parse_t *parse;

	parse = mowgli_alloc(sizeof *parse);

	parse->out = mowgli_list_create();
	parse->error[0] = '\0';
	parse->multidoc = multidoc;
	parse->build = mowgli_list_create();
	parse->top = 0;
	parse->buf = mowgli_string_create();
	parse->lex = LEX_LIMBO;

	ll_push(parse, NTS_JSON_DOCUMENT);

	return parse;
}

void
mowgli_json_parse_destroy(mowgli_json_parse_t *parse)
{
	mowgli_node_t *n;

	return_if_fail(parse != NULL);

	MOWGLI_LIST_FOREACH(n, parse->out->head)
	mowgli_json_decref(n->data);
	MOWGLI_LIST_FOREACH(n, parse->build->head)
	mowgli_json_decref(n->data);

	mowgli_list_free(parse->out);
	mowgli_list_free(parse->build);
	mowgli_string_destroy(parse->buf);

	mowgli_free(parse);
}

void
mowgli_json_parse_reset(mowgli_json_parse_t *parse, bool multidoc)
{
	mowgli_node_t *n, *tn;

	if (parse->out == NULL)
		parse->out = mowgli_list_create();

	if (parse->build == NULL)
		parse->build = mowgli_list_create();

	MOWGLI_LIST_FOREACH_SAFE(n, tn, parse->out->head)
	{
		mowgli_json_decref(n->data);
		mowgli_node_delete(n, parse->out);
	}
	MOWGLI_LIST_FOREACH_SAFE(n, tn, parse->build->head)
	{
		mowgli_json_decref(n->data);
		mowgli_node_delete(n, parse->build);
	}

	parse->error[0] = '\0';
	parse->multidoc = multidoc;
	parse->top = 0;

	if (parse->buf == NULL)
		parse->buf = mowgli_string_create();
	else
		mowgli_string_reset(parse->buf);

	parse->lex = LEX_LIMBO;

	ll_push(parse, NTS_JSON_DOCUMENT);
}

void
mowgli_json_parse_data(mowgli_json_parse_t *parse, const char *data, size_t len)
{
	while (len > 0)
	{
		/* We cannot continue parsing if there's an error! */
		if (mowgli_json_parse_error(parse))
			return;

		while (lex_char(parse, *data))
		{ }

		data++;
		len--;
	}
}

char *
mowgli_json_parse_error(mowgli_json_parse_t *parse)
{
	if (parse->error[0])
		return parse->error;

	return NULL;
}

bool
mowgli_json_parse_more(mowgli_json_parse_t *parse)
{
	return !parse_out_empty(parse);
}

mowgli_json_t *
mowgli_json_parse_next(mowgli_json_parse_t *parse)
{
	return parse_out_dequeue(parse);
}

/* Note: Static parsers like these should last the life of the program,
   since mowgli_json_parse_destroy will attempt to mowgli_free the
   parser. */

static mowgli_json_parse_t static_parser;

mowgli_json_t *
mowgli_json_parse_file(const char *path)
{
	char *s;
	char buf[512];
	size_t n;
	mowgli_json_t *ret;
	FILE *f;

	mowgli_json_parse_reset(&static_parser, false);

	f = fopen(path, "r");

	if (f == NULL)
	{
		mowgli_log("Could not open %s for reading", path);
		return NULL;
	}

	s = NULL;

	while (!feof(f) && s == NULL)
	{
		n = fread(buf, 1, 512, f);
		mowgli_json_parse_data(&static_parser, buf, n);

		s = mowgli_json_parse_error(&static_parser);
	}

	if (s != NULL)
	{
		mowgli_log("%s: %s", path, s);
		ret = NULL;
	}
	else
	{
		ret = mowgli_json_parse_next(&static_parser);

		if (ret == NULL)
			mowgli_log("%s: Incomplete JSON document", path);
	}

	fclose(f);

	return ret;
}

mowgli_json_t *
mowgli_json_parse_string(const char *data)
{
	mowgli_json_t *ret;
	char *s;

	mowgli_json_parse_reset(&static_parser, false);

	mowgli_json_parse_data(&static_parser, data, strlen(data));

	if ((s = mowgli_json_parse_error(&static_parser)) != NULL)
	{
		mowgli_log("%s", s);
		ret = NULL;
	}
	else
	{
		ret = mowgli_json_parse_next(&static_parser);

		if (ret == NULL)
			mowgli_log("Incomplete JSON document");
	}

	return ret;
}
