/*
 * Copyright (C) 2021 Jo-Philipp Wich <jo@mein.io>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <stdarg.h>
#include <stdlib.h>
#include <assert.h>
#include <endian.h>
#include <errno.h>
#include <math.h>

#include "types.h"
#include "util.h"
#include "vm.h"

uc_type_t
ucv_type(uc_value_t *uv)
{
	uc_type_t type = ((uintptr_t)uv & 3);

	if (type == UC_NULL && uv != NULL)
		type = uv->type;

	return type;
}

const char *
ucv_typename(uc_value_t *uv)
{
	switch (ucv_type(uv)) {
	case UC_NULL:      return "null";
	case UC_INTEGER:   return "integer";
	case UC_BOOLEAN:   return "boolean";
	case UC_STRING:    return "string";
	case UC_DOUBLE:    return "double";
	case UC_ARRAY:     return "array";
	case UC_OBJECT:    return "object";
	case UC_REGEXP:    return "regexp";
	case UC_FUNCTION:  return "function";
	case UC_CFUNCTION: return "cfunction";
	case UC_CLOSURE:   return "closure";
	case UC_UPVALUE:   return "upvalue";
	case UC_RESSOURCE: return "ressource";
	}

	return "unknown";
}

static uc_ressource_type_t *
ucv_ressource_type_get(size_t type);

static void
ucv_unref(uc_weakref_t *ref)
{
	ref->prev->next = ref->next;
	ref->next->prev = ref->prev;
}

static void
ucv_ref(uc_weakref_t *head, uc_weakref_t *item)
{
	item->next = head->next;
	item->prev = head;
	head->next->prev = item;
	head->next = item;
}

#if 0
static uc_weakref_t *
ucv_get_weakref(uc_value_t *uv)
{
	switch (ucv_type(uv)) {
	case UC_ARRAY:
		return &((uc_array_t *)uv)->ref;

	case UC_OBJECT:
		return &((uc_object_t *)uv)->ref;

	case UC_CLOSURE:
		return &((uc_closure_t *)uv)->ref;

	default:
		return NULL;
	}
}
#endif

static void
ucv_put_value(uc_value_t *uv, bool retain)
{
	if (uv == NULL || (uintptr_t)uv & 3)
		return;

	assert(uv->refcount > 0);

	if (uv->refcount > 0)
		uv->refcount--;

	if (uv->refcount == 0)
		ucv_free(uv, retain);
}

static void
ucv_gc_mark(uc_value_t *uv);

static void
ucv_gc_mark(uc_value_t *uv)
{
	uc_function_t *function;
	uc_closure_t *closure;
	uc_upvalref_t *upval;
	uc_object_t *object;
	uc_array_t *array;
	struct lh_entry *entry;
	size_t i;

	switch (ucv_type(uv)) {
	case UC_ARRAY:
		array = (uc_array_t *)uv;

		ucv_gc_mark(array->proto);

		for (i = 0; i < array->count; i++)
			ucv_gc_mark(array->entries[i]);

		if (array->ref.next)
			ucv_set_mark(uv);

		break;

	case UC_OBJECT:
		object = (uc_object_t *)uv;

		ucv_gc_mark(object->proto);

		lh_foreach(object->table, entry)
			ucv_gc_mark((uc_value_t *)lh_entry_v(entry));

		if (object->ref.next)
			ucv_set_mark(uv);

		break;

	case UC_CLOSURE:
		closure = (uc_closure_t *)uv;
		function = closure->function;

		for (i = 0; i < function->nupvals; i++)
			ucv_gc_mark((uc_value_t *)closure->upvals[i]);

		ucv_gc_mark((uc_value_t *)function);

		if (closure->ref.next)
			ucv_set_mark(uv);

		break;

	case UC_UPVALUE:
		upval = (uc_upvalref_t *)uv;
		ucv_gc_mark(upval->value);
		break;

	default:
		break;
	}
}

void
ucv_free(uc_value_t *uv, bool retain)
{
	uc_ressource_type_t *restype;
	uc_ressource_t *ressource;
	uc_function_t *function;
	uc_closure_t *closure;
	uc_upvalref_t *upval;
	uc_regexp_t *regexp;
	uc_object_t *object;
	uc_array_t *array;
	uc_weakref_t *ref;
	size_t i;

	if (uv == NULL || (uintptr_t)uv & 3)
		return;

	if (uv->mark)
		return;

	uv->mark = true;

	ref = NULL;

	switch (uv->type) {
	case UC_ARRAY:
		array = (uc_array_t *)uv;
		ref = &array->ref;
		ucv_put_value(array->proto, retain);

		for (i = 0; i < array->count; i++)
			ucv_put_value(array->entries[i], retain);

		uc_vector_clear(array);
		break;

	case UC_OBJECT:
		object = (uc_object_t *)uv;
		ref = &object->ref;
		ucv_put_value(object->proto, retain);
		lh_table_free(object->table);
		break;

	case UC_REGEXP:
		regexp = (uc_regexp_t *)uv;
		regfree(&regexp->regexp);
		break;

	case UC_FUNCTION:
		function = (uc_function_t *)uv;
		uc_chunk_free(&function->chunk);
		uc_source_put(function->source);
		break;

	case UC_CLOSURE:
		closure = (uc_closure_t *)uv;
		function = closure->function;
		ref = &closure->ref;

		for (i = 0; i < function->nupvals; i++)
			ucv_put_value((uc_value_t *)closure->upvals[i], retain);

		ucv_put_value((uc_value_t *)function, retain);
		break;

	case UC_RESSOURCE:
		ressource = (uc_ressource_t *)uv;
		restype = ucv_ressource_type_get(ressource->type);

		if (restype && restype->free)
			restype->free(ressource->data);

		break;

	case UC_UPVALUE:
		upval = (uc_upvalref_t *)uv;
		ucv_put_value(upval->value, retain);
		break;
	}

	if (!ref || !retain) {
		if (ref && ref->prev && ref->next)
			ucv_unref(ref);

		free(uv);
	}
	else {
		uv->type = UC_NULL;
	}
}

void
ucv_put(uc_value_t *uv)
{
	ucv_put_value(uv, false);
}

uc_value_t *
ucv_get(uc_value_t *uv)
{
	if (uv == NULL || (uintptr_t)uv & 3)
		return uv;

	assert(uv->refcount < 0x03ffffff);

	uv->refcount++;

	return uv;
}

uc_value_t *
ucv_boolean_new(bool val)
{
	uintptr_t pv = UC_BOOLEAN | (val << 2);

	return (uc_value_t *)pv;
}

bool
ucv_boolean_get(uc_value_t *uv)
{
	uintptr_t pv = (uintptr_t)uv;

	if ((pv & 3) == UC_BOOLEAN)
		return (pv >> 2) & 1;

	return false;
}


uc_value_t *
ucv_string_new(const char *str)
{
	return ucv_string_new_length(str, strlen(str));
}

uc_value_t *
ucv_string_new_length(const char *str, size_t length)
{
	uc_string_t *ustr;
	uintptr_t pv;
	size_t i;
	char *s;

	if ((length + 1) < sizeof(void *)) {
		pv = UC_STRING | (length << 2);

#if __BYTE_ORDER == __LITTLE_ENDIAN
		s = (char *)&pv + 1;
#else
		s = (char *)&pv;
#endif

		for (i = 0; i < length; i++)
			s[i] = str[i];

		return (uc_value_t *)pv;
	}

	ustr = xalloc(sizeof(*ustr) + length + 1);
	ustr->header.type = UC_STRING;
	ustr->header.refcount = 1;
	ustr->length = length;
	memcpy(ustr->str, str, length);

	return &ustr->header;
}

uc_stringbuf_t *
ucv_stringbuf_new(void)
{
	uc_stringbuf_t *sb = xprintbuf_new();
	uc_string_t ustr = {
		.header = {
			.type = UC_STRING,
			.refcount = 1
		}
	};

	printbuf_memappend_fast(sb, (char *)&ustr, sizeof(ustr));

	return sb;
}

uc_value_t *
ucv_stringbuf_finish(uc_stringbuf_t *sb)
{
	uc_string_t *ustr = (uc_string_t *)sb->buf;

	ustr->length = printbuf_length(sb) - offsetof(uc_string_t, str);

	free(sb);

	return &ustr->header;
}

char *
_ucv_string_get(uc_value_t **uv)
{
	uc_string_t *str;

	switch ((uintptr_t)*uv & 3) {
	case UC_STRING:
#if __BYTE_ORDER == __LITTLE_ENDIAN
		return (char *)uv + 1;
#else
		return (char *)uv;
#endif

	case UC_NULL:
		if (*uv != NULL && (*uv)->type == UC_STRING) {
			str = (uc_string_t *)*uv;

			return str->str;
		}
	}

	return NULL;
}

size_t
ucv_string_length(uc_value_t *uv)
{
	uc_string_t *str = (uc_string_t *)uv;
	uintptr_t pv = (uintptr_t)uv;

	if ((pv & 3) == UC_STRING)
		return (pv & 0xff) >> 2;
	else if (uv != NULL && uv->type == UC_STRING)
		return str->length;

	return 0;
}


uc_value_t *
ucv_int64_new(int64_t n)
{
	uint64_t uval = (n < 0) ? ((n > INT64_MIN) ? (~n + 1) : INT64_MAX) : n;
	uint64_t max = (1ULL << ((sizeof(void *) * 8) - 3)) - 1;
	uc_integer_t *integer;
	uintptr_t pv;

	if (uval <= max) {
		pv = UC_INTEGER | ((n < 0) << 2) | (uval << 3);

		return (uc_value_t *)pv;
	}

	integer = xalloc(sizeof(*integer));
	integer->header.type = UC_INTEGER;
	integer->header.refcount = 1;
	integer->header.u64 = 0;
	integer->i.s64 = n;

	return &integer->header;
}

uc_value_t *
ucv_uint64_new(uint64_t n)
{
	uint64_t max = (1ULL << ((sizeof(void *) * 8) - 3)) - 1;
	uc_integer_t *integer;
	uintptr_t pv;

	if (n <= max) {
		pv = UC_INTEGER | (n << 3);

		return (uc_value_t *)pv;
	}

	integer = xalloc(sizeof(*integer));
	integer->header.type = UC_INTEGER;
	integer->header.refcount = 1;
	integer->header.u64 = 1;
	integer->i.u64 = n;

	return &integer->header;
}

uint64_t
ucv_uint64_get(uc_value_t *uv)
{
	uintptr_t pv = (uintptr_t)uv;
	uc_integer_t *integer;

	errno = 0;

	if ((pv & 3) == UC_INTEGER) {
		if (((pv >> 2) & 1) == 0)
			return (uint64_t)(pv >> 3);

		errno = ERANGE;

		return 0;
	}
	else if (uv != NULL && uv->type == UC_INTEGER) {
		integer = (uc_integer_t *)uv;

		if (integer->header.u64)
			return integer->i.u64;

		if (integer->i.s64 >= 0)
			return (uint64_t)integer->i.s64;

		errno = ERANGE;

		return 0;
	}

	errno = EINVAL;

	return 0;
}

int64_t
ucv_int64_get(uc_value_t *uv)
{
	uintptr_t pv = (uintptr_t)uv;
	uc_integer_t *integer;

	errno = 0;

	if ((pv & 3) == UC_INTEGER) {
		if (((pv >> 2) & 1) == 0)
			return (int64_t)(pv >> 3);

		return -(int64_t)(pv >> 3);
	}
	else if (uv != NULL && uv->type == UC_INTEGER) {
		integer = (uc_integer_t *)uv;

		if (integer->header.u64 && integer->i.u64 <= INT64_MAX)
			return (int64_t)integer->i.u64;

		if (!integer->header.u64)
			return integer->i.s64;

		errno = ERANGE;

		return 0;
	}

	errno = EINVAL;

	return 0;
}


uc_value_t *
ucv_double_new(double d)
{
	uc_double_t *dbl;

	dbl = xalloc(sizeof(*dbl));
	dbl->header.type = UC_DOUBLE;
	dbl->header.refcount = 1;
	dbl->dbl = d;

	return &dbl->header;
}

double
ucv_double_get(uc_value_t *uv)
{
	uc_double_t *dbl;

	errno = 0;

	if (ucv_type(uv) != UC_DOUBLE) {
		errno = EINVAL;

		return NAN;
	}

	dbl = (uc_double_t *)uv;

	return dbl->dbl;
}


uc_value_t *
ucv_array_new(uc_vm *vm)
{
	return ucv_array_new_length(vm, 0);
}

uc_value_t *
ucv_array_new_length(uc_vm *vm, size_t length)
{
	uc_array_t *array;

	/* XXX */
	length = 0;

	array = xalloc(sizeof(*array) + length * sizeof(array->entries[0]));
	array->header.type = UC_ARRAY;
	array->header.refcount = 1;

	if (length > 0)
		array->count = length;

	uc_vector_grow(array);

	if (vm)
		ucv_ref(&vm->values, &array->ref);

	return &array->header;
}

uc_value_t *
ucv_array_pop(uc_value_t *uv)
{
	uc_array_t *array = (uc_array_t *)uv;
	uc_value_t *item;

	if (ucv_type(uv) != UC_ARRAY || array->count == 0)
		return NULL;

	item = ucv_get(array->entries[array->count - 1]);

	ucv_array_delete(uv, array->count - 1, 1);

	return item;
}

uc_value_t *
ucv_array_push(uc_value_t *uv, uc_value_t *item)
{
	uc_array_t *array = (uc_array_t *)uv;

	if (ucv_type(uv) != UC_ARRAY)
		return NULL;

	ucv_array_set(uv, array->count, item);

	return item;
}

uc_value_t *
ucv_array_shift(uc_value_t *uv)
{
	uc_array_t *array = (uc_array_t *)uv;
	uc_value_t *item;

	if (ucv_type(uv) != UC_ARRAY || array->count == 0)
		return NULL;

	item = ucv_get(array->entries[0]);

	ucv_array_delete(uv, 0, 1);

	return item;
}

uc_value_t *
ucv_array_unshift(uc_value_t *uv, uc_value_t *item)
{
	uc_array_t *array = (uc_array_t *)uv;
	size_t i;

	if (ucv_type(uv) != UC_ARRAY || array->count == 0)
		return NULL;

	array->count++;
	uc_vector_grow(array);

	for (i = array->count; i > 1; i--)
		array->entries[i - 1] = array->entries[i - 2];

	array->entries[0] = item;

	return item;
}

void
ucv_array_sort(uc_value_t *uv, int (*cmp)(const void *, const void *))
{
	uc_array_t *array = (uc_array_t *)uv;

	if (ucv_type(uv) != UC_ARRAY || array->count <= 1)
		return;

	qsort(array->entries, array->count, sizeof(array->entries[0]), cmp);
}

bool
ucv_array_delete(uc_value_t *uv, size_t offset, size_t count)
{
	uc_array_t *array = (uc_array_t *)uv;
	size_t i;

	if (ucv_type(uv) != UC_ARRAY || array->count == 0)
		return false;

	if (offset >= array->count)
		return false;

	if ((offset + count) < offset)
		return false;

	if ((offset + count) > array->count)
		count = array->count - offset;

	for (i = 0; i < count; i++)
		ucv_put(array->entries[offset + i]);

	memmove(&array->entries[offset],
	        &array->entries[offset + count],
	        (array->count - (offset + count)) * sizeof(array->entries[0]));

	array->count -= count;

	uc_vector_grow(array);

	return true;
}

bool
ucv_array_set(uc_value_t *uv, size_t index, uc_value_t *item)
{
	uc_array_t *array = (uc_array_t *)uv;

	if (ucv_type(uv) != UC_ARRAY)
		return false;

	if (index >= array->count) {
		array->count = index + 1;
		uc_vector_grow(array);
	}
	else {
		ucv_put(array->entries[index]);
	}

	array->entries[index] = item;

	return true;
}

uc_value_t *
ucv_array_get(uc_value_t *uv, size_t index)
{
	uc_array_t *array = (uc_array_t *)uv;

	if (ucv_type(uv) != UC_ARRAY)
		return NULL;

	if (index >= array->count)
		return NULL;

	return array->entries[index];
}
size_t
ucv_array_length(uc_value_t *uv)
{
	uc_array_t *array = (uc_array_t *)uv;

	if (ucv_type(uv) != UC_ARRAY)
		return 0;

	return array->count;
}


static void
ucv_free_object_entry(struct lh_entry *entry)
{
	free(lh_entry_k(entry));
	ucv_put(lh_entry_v(entry));
}

uc_value_t *
ucv_object_new(uc_vm *vm)
{
	struct lh_table *table;
	uc_object_t *object;

	table = lh_kchar_table_new(16, ucv_free_object_entry);

	if (!table) {
		fprintf(stderr, "Out of memory\n");
		abort();
	}

	object = xalloc(sizeof(*object));
	object->header.type = UC_OBJECT;
	object->header.refcount = 1;
	object->table = table;

	if (vm)
		ucv_ref(&vm->values, &object->ref);

	return &object->header;
}

bool
ucv_object_add(uc_value_t *uv, const char *key, uc_value_t *val)
{
	uc_object_t *object = (uc_object_t *)uv;
	struct lh_entry *existing_entry;
	uc_value_t *existing_value;
	unsigned long hash;
	void *k;

	if (ucv_type(uv) != UC_OBJECT)
		return false;

	hash = lh_get_hash(object->table, (const void *)key);
	existing_entry = lh_table_lookup_entry_w_hash(object->table, (const void *)key, hash);

	if (existing_entry == NULL) {
		k = xstrdup(key);

		if (lh_table_insert_w_hash(object->table, k, val, hash, 0) != 0) {
			free(k);

			return false;
		}

		return true;
	}

	existing_value = (uc_value_t *)lh_entry_v(existing_entry);

	if (existing_value)
		ucv_put(existing_value);

	existing_entry->v = val;

	return true;
}

bool
ucv_object_delete(uc_value_t *uv, const char *key)
{
	uc_object_t *object = (uc_object_t *)uv;

	if (ucv_type(uv) != UC_OBJECT)
		return false;

	return (lh_table_delete(object->table, key) == 0);
}

uc_value_t *
ucv_object_get(uc_value_t *uv, const char *key, bool *found)
{
	uc_object_t *object = (uc_object_t *)uv;
	uc_value_t *val = NULL;
	bool rv;

	if (found != NULL)
		*found = false;

	if (ucv_type(uv) != UC_OBJECT)
		return NULL;

	rv = lh_table_lookup_ex(object->table, (const void *)key, (void **)&val);

	if (found != NULL)
		*found = rv;

	return val;
}

size_t
ucv_object_length(uc_value_t *uv)
{
	uc_object_t *object = (uc_object_t *)uv;

	if (ucv_type(uv) != UC_OBJECT)
		return 0;

	return lh_table_length(object->table);
}


uc_value_t *
ucv_function_new(const char *name, size_t srcpos, uc_source *source)
{
	size_t namelen = 0;
	uc_function_t *fn;

	if (name)
		namelen = strlen(name);

	fn = xalloc(sizeof(*fn) + namelen + 1);
	fn->header.type = UC_FUNCTION;
	fn->header.refcount = 1;

	if (name)
		strcpy(fn->name, name);

	fn->nargs = 0;
	fn->nupvals = 0;
	fn->srcpos = srcpos;
	fn->source = uc_source_get(source);
	fn->vararg = false;

	uc_chunk_init(&fn->chunk);

	return &fn->header;
}

size_t
ucv_function_srcpos(uc_value_t *uv, size_t off)
{
	uc_function_t *fn = (uc_function_t *)uv;
	size_t pos;

	if (ucv_type(uv) != UC_FUNCTION)
		return 0;

	pos = uc_chunk_debug_get_srcpos(&fn->chunk, off);

	return pos ? fn->srcpos + pos : 0;
}


uc_value_t *
ucv_cfunction_new(const char *name, uc_cfn_ptr_t fptr)
{
	uc_cfunction_t *cfn;
	size_t namelen = 0;

	if (name)
		namelen = strlen(name);

	cfn = xalloc(sizeof(*cfn) + namelen + 1);
	cfn->header.type = UC_CFUNCTION;
	cfn->header.refcount = 1;

	if (name)
		strcpy(cfn->name, name);

	cfn->cfn = fptr;

	return &cfn->header;
}


uc_value_t *
ucv_closure_new(uc_vm *vm, uc_function_t *function, bool arrow_fn)
{
	uc_closure_t *closure;

	closure = xalloc(sizeof(*closure) + (sizeof(uc_upvalref_t *) * function->nupvals));
	closure->header.type = UC_CLOSURE;
	closure->header.refcount = 1;
	closure->function = function;
	closure->is_arrow = arrow_fn;
	closure->upvals = function->nupvals ? ((void *)closure + ALIGN(sizeof(*closure))) : NULL;

	if (vm)
		ucv_ref(&vm->values, &closure->ref);

	return &closure->header;
}


static uc_ressource_types_t res_types;

uc_ressource_type_t *
ucv_ressource_type_add(const char *name, uc_value_t *proto, void (*freefn)(void *))
{
	uc_ressource_type_t *existing;

	existing = ucv_ressource_type_lookup(name);

	if (existing) {
		ucv_put(proto);

		return existing;
	}

	uc_vector_grow(&res_types);

	res_types.entries[res_types.count].name = name;
	res_types.entries[res_types.count].proto = proto;
	res_types.entries[res_types.count].free = freefn;

	return &res_types.entries[res_types.count++];
}

static uc_ressource_type_t *
ucv_ressource_type_get(size_t type)
{
	return (type < res_types.count) ? &res_types.entries[type] : NULL;
}

uc_ressource_type_t *
ucv_ressource_type_lookup(const char *name)
{
	size_t i;

	for (i = 0; i < res_types.count; i++)
		if (!strcmp(res_types.entries[i].name, name))
			return &res_types.entries[i];

	return NULL;
}


uc_value_t *
ucv_ressource_new(uc_ressource_type_t *type, void *data)
{
	uc_ressource_t *res;

	res = xalloc(sizeof(*res));
	res->header.type = UC_RESSOURCE;
	res->header.refcount = 1;
	res->type = type - res_types.entries;
	res->data = data;

	return &res->header;
}

void **
ucv_ressource_dataptr(uc_value_t *uv, const char *name)
{
	uc_ressource_t *res = (uc_ressource_t *)uv;
	uc_ressource_type_t *type;

	if (ucv_type(uv) != UC_RESSOURCE)
		return NULL;

	if (name) {
		type = ucv_ressource_type_lookup(name);

		if (!type || type != ucv_ressource_type_get(res->type))
			return NULL;
	}

	return &res->data;
}


uc_value_t *
ucv_regexp_new(const char *pattern, bool icase, bool newline, bool global, char **error)
{
	int cflags = REG_EXTENDED, res;
	uc_regexp_t *re;
	size_t len;

	re = xalloc(sizeof(*re) + strlen(pattern) + 1);
	re->header.type = UC_REGEXP;
	re->header.refcount = 1;
	re->icase = icase;
	re->global = global;
	re->newline = newline;
	strcpy(re->source, pattern);

	if (icase)
		cflags |= REG_ICASE;

	if (newline)
		cflags |= REG_NEWLINE;

	res = regcomp(&re->regexp, pattern, cflags);

	if (res != 0) {
		if (error) {
			len = regerror(res, &re->regexp, NULL, 0);
			*error = xalloc(len);

			regerror(res, &re->regexp, *error, len);
		}

		free(re);

		return NULL;
	}

	/*
	json_object_object_add(re->header.jso, "source", xjs_new_string(pattern));
	json_object_object_add(re->header.jso, "i", xjs_new_boolean(icase));
	json_object_object_add(re->header.jso, "g", xjs_new_boolean(global));
	json_object_object_add(re->header.jso, "s", xjs_new_boolean(newline));
	*/

	return &re->header;
}


uc_value_t *
ucv_upvalref_new(size_t slot)
{
	uc_upvalref_t *up;

	up = xalloc(sizeof(*up));
	up->header.type = UC_UPVALUE;
	up->header.refcount = 1;
	up->slot = slot;

	return &up->header;
}


uc_value_t *
ucv_prototype_get(uc_value_t *uv)
{
	uc_ressource_type_t *restype;
	uc_ressource_t *ressource;
	uc_object_t *object;
	uc_array_t *array;

	switch (ucv_type(uv)) {
	case UC_ARRAY:
		array = (uc_array_t *)uv;

		return array->proto;

	case UC_OBJECT:
		object = (uc_object_t *)uv;

		return object->proto;

	case UC_RESSOURCE:
		ressource = (uc_ressource_t *)uv;
		restype = ucv_ressource_type_get(ressource->type);

		return restype ? restype->proto : NULL;

	default:
		return NULL;
	}
}

bool
ucv_prototype_set(uc_value_t *uv, uc_value_t *proto)
{
	uc_object_t *object;
	uc_array_t *array;

	if (ucv_type(proto) != UC_OBJECT)
		return false;

	switch (ucv_type(uv)) {
	case UC_ARRAY:
		array = (uc_array_t *)uv;
		array->proto = proto;

		return true;

	case UC_OBJECT:
		object = (uc_object_t *)uv;
		object->proto = proto;

		return true;

	default:
		return false;
	}
}

uc_value_t *
ucv_property_get(uc_value_t *uv, const char *key)
{
	uc_value_t *val;
	bool found;

	for (; uv; uv = ucv_prototype_get(uv)) {
		val = ucv_object_get(uv, key, &found);

		if (found)
			return val;
	}

	return NULL;
}


uc_value_t *
ucv_from_json(uc_vm *vm, json_object *jso)
{
	//uc_array_t *arr;
	uc_value_t *uv, *item;
	int64_t n;
	size_t i;

	switch (json_object_get_type(jso)) {
	case json_type_null:
		return NULL;

	case json_type_boolean:
		return ucv_boolean_new(json_object_get_boolean(jso));

	case json_type_double:
		return ucv_double_new(json_object_get_double(jso));

	case json_type_int:
		n = json_object_get_int64(jso);

		if (n == INT64_MAX)
			return ucv_uint64_new(json_object_get_uint64(jso));

		return ucv_int64_new(n);

	case json_type_object:
		uv = ucv_object_new(vm);

		json_object_object_foreach(jso, key, val) {
			item = ucv_from_json(vm, val);

			if (!ucv_object_add(uv, key, item))
				ucv_put(item);

#ifdef __clang_analyzer__
			/* Clang static analyzer does not understand that the object retains
			 * our item so pretend to free it here to suppress the false positive
			 * memory leak warning. */
			ucv_put(item);
#endif
		}

		return uv;

	case json_type_array:
		/* XXX
		arr = (uc_array_t *)ucv_array_new_length(vm, json_object_array_length(jso));

		for (i = 0; i < arr->count; i++)
			arr->entries[i] = ucv_from_json(vm, json_object_array_get_idx(jso, i));

		return &arr->header;
		*/
		uv = ucv_array_new(vm);

		for (i = 0; i < json_object_array_length(jso); i++) {
			item = ucv_from_json(vm, json_object_array_get_idx(jso, i));

			if (!ucv_array_push(uv, item))
				ucv_put(item);

#ifdef __clang_analyzer__
			/* Clang static analyzer does not understand that the array retains
			 * our item so pretend to free it here to suppress the false positive
			 * memory leak warning. */
			ucv_put(item);
#endif
		}

		return uv;

	case json_type_string:
		return ucv_string_new_length(json_object_get_string(jso), json_object_get_string_len(jso));
	}

	return NULL;
}

json_object *
ucv_to_json(uc_value_t *uv)
{
	uc_regexp_t *regexp;
	uc_array_t *array;
	json_object *jso;
	size_t i;
	char *s;

	switch (ucv_type(uv)) {
	case UC_BOOLEAN:
		return json_object_new_boolean(ucv_boolean_get(uv));

	case UC_INTEGER:
		if (ucv_is_u64(uv))
			return json_object_new_uint64(ucv_uint64_get(uv));

		return json_object_new_int64(ucv_int64_get(uv));

	case UC_DOUBLE:
		return json_object_new_double(ucv_double_get(uv));

	case UC_STRING:
		return json_object_new_string_len(ucv_string_get(uv), ucv_string_length(uv));

	case UC_ARRAY:
		array = (uc_array_t *)uv;
		jso = json_object_new_array_ext(array->count);

		for (i = 0; i < array->count; i++)
			json_object_array_put_idx(jso, i, ucv_to_json(array->entries[i]));

		return jso;

	case UC_OBJECT:
		jso = json_object_new_object();

		ucv_object_foreach(uv, key, val)
			json_object_object_add(jso, key, ucv_to_json(val));

		return jso;

	case UC_REGEXP:
		regexp = (uc_regexp_t *)uv;
		i = asprintf(&s, "/%s/%s%s%s",
			regexp->source,
			regexp->global ? "g" : "",
			regexp->icase ? "i" : "",
			regexp->newline ? "s" : "");

		if (i <= 0)
			return NULL;

		jso = json_object_new_string_len(s, i);

		free(s);

		return jso;

	case UC_CLOSURE:
	case UC_CFUNCTION:
	case UC_FUNCTION:
	case UC_RESSOURCE:
	case UC_UPVALUE:
	case UC_NULL:
		return NULL;
	}

	return NULL;
}

static void
ucv_to_string_json_encoded(uc_stringbuf_t *pb, const char *s, size_t len, bool regexp)
{
	size_t i;

	if (!regexp)
		ucv_stringbuf_append(pb, "\"");

	for (i = 0; s != NULL && i < len; i++, s++) {
		switch (*s) {
		case '"':
			ucv_stringbuf_append(pb, "\\\"");
			break;

		case '\\':
			ucv_stringbuf_append(pb, "\\\\");
			break;

		case '\b':
			ucv_stringbuf_append(pb, "\\b");
			break;

		case '\f':
			ucv_stringbuf_append(pb, "\\f");
			break;

		case '\n':
			ucv_stringbuf_append(pb, "\\n");
			break;

		case '\r':
			ucv_stringbuf_append(pb, "\\r");
			break;

		case '\t':
			ucv_stringbuf_append(pb, "\\t");
			break;

		case '/':
			if (regexp)
				ucv_stringbuf_append(pb, "\\");

			ucv_stringbuf_append(pb, "/");
			break;

		default:
			if (*s < 0x20)
				ucv_stringbuf_printf(pb, "\\u%04x", *s);
			else
				ucv_stringbuf_addstr(pb, s, 1);
			break;
		}
	}

	if (!regexp)
		ucv_stringbuf_append(pb, "\"");
}

static bool
ucv_call_tostring(uc_vm *vm, uc_stringbuf_t *pb, uc_value_t *uv, bool json)
{
	uc_value_t *proto = ucv_prototype_get(uv);
	uc_value_t *tostr = ucv_object_get(proto, "tostring", NULL);
	uc_value_t *str;
	size_t l;
	char *s;

	if (!ucv_is_callable(tostr))
		return false;

	uc_vm_stack_push(vm, ucv_get(uv));
	uc_vm_stack_push(vm, ucv_get(tostr));

	if (uc_vm_call(vm, true, 0) != EXCEPTION_NONE)
		return false;

	str = uc_vm_stack_pop(vm);

	if (ucv_type(str) == UC_STRING) {
		s = ucv_string_get(str);
		l = ucv_string_length(str);

		if (json)
			ucv_to_string_json_encoded(pb, s, l, false);
		else if (s)
			ucv_stringbuf_addstr(pb, s, l);
	}
	else if (json) {
		ucv_stringbuf_append(pb, "\"\"");
	}

	ucv_put(str);

	return true;
}

void
_ucv_stringbuf_append(uc_stringbuf_t *pb, const char *str, size_t len)
{
	printbuf_memappend_fast(pb, str, len);
}

void
ucv_to_stringbuf(uc_vm *vm, uc_stringbuf_t *pb, uc_value_t *uv, bool json)
{
	uc_ressource_type_t *restype;
	uc_ressource_t *ressource;
	uc_cfunction_t *cfunction;
	uc_function_t *function;
	uc_closure_t *closure;
	uc_regexp_t *regexp;
	uc_value_t *argname;
	uc_array_t *array;
	size_t i, l;
	double d;
	char *s;

	if (ucv_is_marked(uv)) {
		ucv_stringbuf_append(pb, "null");

		return;
	}

	if (vm != NULL && ucv_call_tostring(vm, pb, uv, json))
		return;

	ucv_set_mark(uv);

	switch (ucv_type(uv)) {
	case UC_NULL:
		ucv_stringbuf_append(pb, "null");
		break;

	case UC_BOOLEAN:
		if (ucv_boolean_get(uv))
			ucv_stringbuf_append(pb, "true");
		else
			ucv_stringbuf_append(pb, "false");
		break;

	case UC_INTEGER:
		if (ucv_is_u64(uv))
			ucv_stringbuf_printf(pb, "%" PRIu64, ucv_uint64_get(uv));
		else
			ucv_stringbuf_printf(pb, "%" PRId64, ucv_int64_get(uv));
		break;

	case UC_DOUBLE:
		d = ucv_double_get(uv);

		if (json && isnan(d))
			ucv_stringbuf_append(pb, "\"NaN\"");
		else if (json && d == INFINITY)
			ucv_stringbuf_append(pb, "1e309");
		else if (json && d == -INFINITY)
			ucv_stringbuf_append(pb, "-1e309");
		else if (isnan(d))
			ucv_stringbuf_append(pb, "NaN");
		else if (d == INFINITY)
			ucv_stringbuf_append(pb, "Infinity");
		else if (d == -INFINITY)
			ucv_stringbuf_append(pb, "-Infinity");
		else
			ucv_stringbuf_printf(pb, "%g", d);

		break;

	case UC_STRING:
		s = ucv_string_get(uv);
		l = ucv_string_length(uv);

		if (s) {
			if (json)
				ucv_to_string_json_encoded(pb, s, l, false);
			else
				ucv_stringbuf_addstr(pb, s, l);
		}

		break;

	case UC_ARRAY:
		array = (uc_array_t *)uv;

		ucv_stringbuf_append(pb, "[");

		for (i = 0; i < array->count; i++) {
			if (i)
				ucv_stringbuf_append(pb, ", ");
			else
				ucv_stringbuf_append(pb, " ");

			ucv_to_stringbuf(vm, pb, array->entries[i], true);
		}

		ucv_stringbuf_append(pb, " ]");
		break;

	case UC_OBJECT:
		ucv_stringbuf_append(pb, "{");

		i = 0;
		ucv_object_foreach(uv, key, val) {
			if (i++)
				ucv_stringbuf_append(pb, ", ");
			else
				ucv_stringbuf_append(pb, " ");

			ucv_to_string_json_encoded(pb, key, strlen(key), false);
			ucv_stringbuf_append(pb, ": ");
			ucv_to_stringbuf(vm, pb, val, true);
		}

		ucv_stringbuf_append(pb, " }");
		break;

	case UC_REGEXP:
		regexp = (uc_regexp_t *)uv;

		if (json)
			ucv_stringbuf_append(pb, "\"");

		ucv_stringbuf_append(pb, "/");
		ucv_to_string_json_encoded(pb, regexp->source, strlen(regexp->source), true);
		ucv_stringbuf_append(pb, "/");

		if (regexp->global)
			ucv_stringbuf_append(pb, "g");

		if (regexp->icase)
			ucv_stringbuf_append(pb, "i");

		if (regexp->newline)
			ucv_stringbuf_append(pb, "s");

		if (json)
			ucv_stringbuf_append(pb, "\"");

		break;

	case UC_CLOSURE:
		closure = (uc_closure_t *)uv;
		function = closure->function;

		if (json)
			ucv_stringbuf_append(pb, "\"");

		if (!closure->is_arrow) {
			ucv_stringbuf_append(pb, "function");

			if (function->name[0]) {
				ucv_stringbuf_append(pb, " ");
				ucv_stringbuf_addstr(pb, function->name, strlen(function->name));
			}
		}

		ucv_stringbuf_append(pb, "(");

		for (i = 1; i <= function->nargs; i++) {
			argname = uc_chunk_debug_get_variable(&function->chunk, i - 1, i, false);

			if (i > 1)
				ucv_stringbuf_append(pb, ", ");

			if (i == function->nargs && function->vararg)
				ucv_stringbuf_append(pb, "...");

			if (argname) {
				s = ucv_string_get(argname);
				l = ucv_string_length(argname);

				if (s)
					ucv_stringbuf_addstr(pb, s, l);

				ucv_put(argname);

				continue;
			}

			ucv_stringbuf_printf(pb, "[arg%zu]", i);
		}

		ucv_stringbuf_printf(pb, ")%s { ... }%s",
			closure->is_arrow ? " =>" : "",
			json ? "\"" : "");

		break;

	case UC_CFUNCTION:
		cfunction = (uc_cfunction_t *)uv;

		ucv_stringbuf_printf(pb, "%sfunction%s%s(...) { [native code] }%s",
			json ? "\"" : "",
			cfunction->name ? " " : "",
			cfunction->name ? cfunction->name : "",
			json ? "\"" : "");

		break;

	case UC_FUNCTION:
		ucv_stringbuf_printf(pb, "%s<function %p>%s",
			json ? "\"" : "",
			uv,
			json ? "\"" : "");

		break;

	case UC_RESSOURCE:
		ressource = (uc_ressource_t *)uv;
		restype = ucv_ressource_type_get(ressource->type);

		ucv_stringbuf_printf(pb, "%s<%s %p>%s",
			json ? "\"" : "",
			restype ? restype->name : "ressource",
			ressource->data,
			json ? "\"" : "");

		break;

	case UC_UPVALUE:
		ucv_stringbuf_printf(pb, "%s<upvalref %p>%s",
			json ? "\"" : "",
			uv,
			json ? "\"" : "");

		break;
	}

	ucv_clear_mark(uv);
}

static char *
ucv_to_string_any(uc_vm *vm, uc_value_t *uv, bool json)
{
	uc_stringbuf_t *pb = xprintbuf_new();
	char *rv;

	ucv_to_stringbuf(vm, pb, uv, json);

	rv = pb->buf;

	free(pb);

	return rv;
}

char *
ucv_to_string(uc_vm *vm, uc_value_t *uv)
{
	return ucv_to_string_any(vm, uv, false);
}

char *
ucv_to_jsonstring(uc_vm *vm, uc_value_t *uv)
{
	return ucv_to_string_any(vm, uv, true);
}

bool
ucv_equal(uc_value_t *uv1, uc_value_t *uv2)
{
	uc_type_t t1 = ucv_type(uv1);
	uc_type_t t2 = ucv_type(uv2);
	const char *s1, *s2;
	uint64_t u1, u2;
	int64_t n1, n2;
	bool b1, b2;

	if (t1 != t2)
		return false;

	if (uv1 == uv2)
		return true;

	switch (t1) {
	case UC_NULL:
		return true;

	case UC_BOOLEAN:
		return ucv_boolean_get(uv1) == ucv_boolean_get(uv2);

	case UC_DOUBLE:
		return ucv_double_get(uv1) == ucv_double_get(uv2);

	case UC_INTEGER:
		n1 = ucv_int64_get(uv1);
		b1 = (errno == 0);

		n2 = ucv_int64_get(uv2);
		b2 = (errno == 0);

		if (b1 && b2)
			return (n1 == n2);

		u1 = ucv_uint64_get(uv1);
		b1 = (errno == 0);

		u2 = ucv_uint64_get(uv2);
		b2 = (errno == 0);

		if (b1 && b2)
			return (u1 == u2);

		return false;

	case UC_STRING:
		s1 = ucv_string_get(uv1);
		s2 = ucv_string_get(uv2);
		u1 = ucv_string_length(uv1);
		u2 = ucv_string_length(uv2);

		if (s1 == NULL || s2 == NULL || u1 != u2)
			return false;

		return (memcmp(s1, s2, u1) == 0);

	case UC_ARRAY:
		u1 = ucv_array_length(uv1);
		u2 = ucv_array_length(uv2);

		if (u1 != u2)
			return false;

		for (u1 = 0; u1 < u2; u1++)
			if (!ucv_equal(ucv_array_get(uv1, u1), ucv_array_get(uv2, u1)))
				return false;

		return true;

	case UC_OBJECT:
		u1 = ucv_object_length(uv1);
		u2 = ucv_object_length(uv2);

		if (u1 != u2)
			return false;

		ucv_object_foreach(uv1, key, val) {
			if (!ucv_equal(val, ucv_object_get(uv2, key, NULL)))
				return false;
		}

		ucv_object_foreach(uv2, key2, val2) {
			ucv_object_get(uv1, key2, &b1);

			if (!b1)
				return false;
		}

		return true;

	default:
		return false;
	}
}

void
ucv_gc(uc_vm *vm, bool final)
{
	uc_weakref_t *ref, *tmp;
	uc_value_t *val;
	size_t i;

	if (!final) {
		/* mark reachable objects */
		ucv_gc_mark(vm->globals);

		for (i = 0; i < vm->callframes.count; i++)
			ucv_gc_mark(vm->callframes.entries[i].ctx);

		for (i = 0; i < vm->stack.count; i++)
			ucv_gc_mark(vm->stack.entries[i]);
	}

	/* unref unreachable objects */
	for (ref = vm->values.next; ref != &vm->values; ref = ref->next) {
		val = (void *)ref - offsetof(uc_array_t, ref);

		if (ucv_is_marked(val))
			ucv_clear_mark(val);
		else
			ucv_free(val, true);
	}

	/* free destroyed objects */
	for (ref = vm->values.next, tmp = ref->next; ref != &vm->values; ref = tmp, tmp = tmp->next) {
		val = (void *)ref - offsetof(uc_array_t, ref);

		if (val->type == UC_NULL) {
			ucv_unref(ref);
			free(val);
		}
	}
}


#ifdef __GNUC__

__attribute__((destructor))
static void ucv_ressource_types_free(void)
{
	size_t i;

	for (i = 0; i < res_types.count; i++)
		ucv_put(res_types.entries[i].proto);

	uc_vector_clear(&res_types);
}

#endif