/*
 * Copyright (C) 2016 Charybdis Development Team
 * Copyright (C) 2016 Jason Volk <jason@zemos.net>
 *
 * 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 is present in all copies.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
 */

#pragma once
#define HAVE_IRCD_JS_STRING_H

namespace ircd  {
namespace js    {

bool external(const JSString *const &);
size_t size(const JSString *const &);
char16_t at(const JSString *const &, const size_t &);

const size_t CSTR_BUFS = 8;
const size_t CSTR_BUFSIZE = 1024;
char *c_str(const JSString *const &);

namespace basic {

template<lifetime L>
struct string
:root<JSString *, L>
{
	IRCD_OVERLOAD(literal)

	char *c_str() const;                         // Copy into rotating buf
	size_t native_size() const;
	size_t size() const;
	bool empty() const;
	char16_t operator[](const size_t &at) const;

	explicit operator std::string() const;
	operator JS::Value() const;

	using root<JSString *, L>::root;
	string(literal_t, const char16_t *const &);
	string(const char16_t *const &, const size_t &len);
	string(const char16_t *const &);
	string(const std::u16string &);
	string(const char *const &, const size_t &len);
	string(const std::string &);
	string(const char *const &);
	string(const value<L> &);
	string(JSString *const &);
	string(JSString &);
	string();

	struct less
	{
		using is_transparent = std::true_type;

		template<class A, class B> bool operator()(const A &, const B &) const;
	};
};

template<class T> constexpr bool is_string();
template<class A, class B> constexpr bool string_argument();

template<lifetime A, lifetime B> int cmp(const string<A> &a, const string<B> &b);
template<lifetime L> int cmp(const char *const &a, const string<L> &b);
template<lifetime L> int cmp(const string<L> &a, const char *const &b);
template<lifetime L> int cmp(const string<L> &a, const std::string &b);
template<lifetime L> int cmp(const std::string &a, const string<L> &b);
template<lifetime L> bool operator==(const string<L> &a, const char *const &b);
template<lifetime L> bool operator==(const char *const &a, const string<L> &b);

template<class A,
         class B>
using string_comparison = typename std::enable_if<string_argument<A, B>(), bool>::type;
template<class A, class B> string_comparison<A, B> operator==(const A &a, const B &b);
template<class A, class B> string_comparison<A, B> operator!=(const A &a, const B &b);
template<class A, class B> string_comparison<A, B> operator>(const A &a, const B &b);
template<class A, class B> string_comparison<A, B> operator<(const A &a, const B &b);
template<class A, class B> string_comparison<A, B> operator>=(const A &a, const B &b);
template<class A, class B> string_comparison<A, B> operator<=(const A &a, const B &b);
template<class A, class B> string_comparison<A, B> operator==(const A &a, const B &b);
template<class A, class B> string_comparison<A, B> operator!=(const A &a, const B &b);

template<lifetime L>
using string_pair = std::pair<string<L>, string<L>>;
template<lifetime L> string_pair<L> split(const typename string<L>::handle &s, const char &c);
template<lifetime L> string_pair<L> split(const typename string<L>::handle &s, const char16_t &c);
template<lifetime L> string<L> substr(const typename string<L>::handle &s, const size_t &pos, const size_t &len);
template<lifetime L> string<L> operator+(const typename string<L>::handle &left, const typename string<L>::handle &right);

template<lifetime L> std::ostream & operator<<(std::ostream &os, const string<L> &s);

} // namespace basic

using string = basic::string<lifetime::stack>;
using heap_string = basic::string<lifetime::heap>;

//
// Implementation
//
namespace basic {

template<lifetime L>
string<L>::string()
:string<L>::root::type
{
	JS_GetEmptyString(*rt)
}
{
}

template<lifetime L>
string<L>::string(JSString &val)
:string<L>::root::type{&val}
{
}

template<lifetime L>
string<L>::string(JSString *const &val)
:string<L>::root::type
{
	likely(val)? val : throw internal_error("NULL string")
}
{
}

template<lifetime L>
string<L>::string(const value<L> &val)
:string<L>::root::type
{
	JS::ToString(*cx, val)?: throw type_error("Failed to convert value to string")
}
{
}

template<lifetime L>
string<L>::string(const std::string &s)
:string(s.data(), s.size())
{
}

template<lifetime L>
string<L>::string(const char *const &s)
:string(s, strlen(s))
{
}

template<lifetime L>
string<L>::string(const char *const &s,
                  const size_t &len)
:string<L>::root::type{[&s, &len]
{
	auto buf(native_external_copy(s, len));
	return JS_NewExternalString(*cx, buf.release(), len, &native_external_delete);
}()}
{
	if(unlikely(!this->get()))
		throw type_error("Failed to construct string from character array");
}

template<lifetime L>
string<L>::string(const std::u16string &s)
:string(s.data(), s.size())
{
}

template<lifetime L>
string<L>::string(const char16_t *const &s)
:string(s, std::char_traits<char16_t>::length(s))
{
}

template<lifetime L>
string<L>::string(const char16_t *const &s,
                  const size_t &len)
:string<L>::root::type{[&s, &len]
{
	// JS_NewExternalString does not require a null terminated buffer, but we are going
	// to terminate anyway in case the deleter ever wants to iterate a canonical vector.
	auto buf(std::make_unique<char16_t[]>(len+1));
	memcpy(buf.get(), s, len * 2);
	buf.get()[len] = char16_t(0);
	return JS_NewExternalString(*cx, buf.release(), len, &native_external_delete);
}()}
{
	if(unlikely(!this->get()))
		throw type_error("Failed to construct string from character array");
}

template<lifetime L>
string<L>::string(literal_t,
                  const char16_t *const &s)
:string<L>::root::type
{
	JS_NewExternalString(*cx, s, std::char_traits<char16_t>::length(s), &native_external_static)
}
{
	if(unlikely(!this->get()))
		throw type_error("Failed to construct string from wide character literal");
}

template<lifetime L>
char16_t
string<L>::operator[](const size_t &pos)
const
{
	return at(this->get(), pos);
}

template<lifetime L>
string<L>::operator JS::Value()
const
{
	return JS::StringValue(this->get());
}

template<lifetime L>
string<L>::operator std::string()
const
{
	return native(this->get());
}

template<lifetime L>
char *
string<L>::c_str()
const
{
	return js::c_str(this->get());
}

template<lifetime L>
bool
string<L>::empty()
const
{
	return size() == 0;
}

template<lifetime L>
size_t
string<L>::size()
const
{
	return js::size(this->get());
}

template<lifetime L>
size_t
string<L>::native_size()
const
{
	return js::native_size(this->get());
}

template<lifetime L>
template<class A,
         class B>
bool
string<L>::less::operator()(const A &a, const B &b)
const
{
	return cmp(a, b) < 0;
}

template<lifetime L>
std::ostream &
operator<<(std::ostream &os, const string<L> &s)
{
	os << std::string(s);
	return os;
}

template<class A,
         class B>
string_comparison<A, B>
operator>(const A &a, const B &b)
{
	return cmp(a, b) > 0;
}

template<class A,
         class B>
string_comparison<A, B>
operator<(const A &a, const B &b)
{
	return cmp(a, b) < 0;
}

template<class A,
         class B>
string_comparison<A, B>
operator>=(const A &a, const B &b)
{
	return cmp(a, b) >= 0;
}

template<class A,
         class B>
string_comparison<A, B>
operator<=(const A &a, const B &b)
{
	return cmp(a, b) <= 0;
}

template<class A,
         class B>
string_comparison<A, B>
operator==(const A &a, const B &b)
{
	return cmp(a, b) == 0;
}

template<class A,
         class B>
string_comparison<A, B>
operator!=(const A &a, const B &b)
{
	return !(operator==(a, b));
}

template<lifetime L>
bool
operator==(const string<L> &a, const char *const &b)
{
	bool ret;
	if(unlikely(!JS_StringEqualsAscii(*cx, a, b, &ret)))
		throw internal_error("Failed to compare string to native");

	return ret;
}

template<lifetime L>
bool
operator==(const char *const &a, const string<L> &b)
{
	bool ret;
	if(unlikely(!JS_StringEqualsAscii(*cx, b, a, &ret)))
		throw internal_error("Failed to compare string to native");

	return ret;
}

template<lifetime L>
int
cmp(const string<L> &a,
    const std::string &b)
{
	return cmp(a, b.c_str());
}

template<lifetime L>
int
cmp(const std::string &a,
    const string<L> &b)
{
	return cmp(a.c_str(), b);
}

template<lifetime L>
int
cmp(const string<L> &a,
    const char *const &b)
{
	return cmp(a, string<L>(b));
}

template<lifetime L>
int
cmp(const char *const &a,
    const string<L> &b)
{
	return cmp(string<L>(a), b);
}

template<lifetime A,
         lifetime B>
int
cmp(const string<A> &a,
    const string<B> &b)
{
	int32_t ret;
	if(unlikely(!JS_CompareStrings(*cx, a, b, &ret)))
		throw internal_error("Failed to compare strings");

	return ret;
}

template<lifetime L>
std::pair<string<L>, string<L>>
split(const typename string<L>::handle &s,
      const char &c)
{
	return {};
}

template<lifetime L>
std::pair<string<L>, string<L>>
split(const typename string<L>::handle &s,
      const char16_t &c)
{
	size_t i(0);
	for(; i < size(s) && at(s, i) != c; ++i);
	return
	{
		substr(s, 0, i),
		i < size(s)? substr(s, i + 1, size(s) - i) : string<L>()
	};
}

template<lifetime L>
string<L>
substr(const typename string<L>::handle &s,
       const size_t &pos,
       const size_t &len)
{
	const auto _len(len == size_t(-1)? size(s) - pos : len);
	const auto ret(JS_NewDependentString(*cx, s, pos, _len));
	if(!ret)
		throw std::out_of_range("substr(): invalid arguments");

	return ret;
}

template<lifetime L>
string<L>
operator+(const typename string<L>::handle &left,
          const typename string<L>::handle &right)
{
	return JS_ConcatStrings(*cx, left, right);
}

template<class A,
         class B>
constexpr bool
string_argument()
{
	return is_string<A>() || is_string<B>();
}

template<class T>
constexpr bool
is_string()
{
	return std::is_base_of<string<lifetime::stack>, T>() ||
	       std::is_base_of<string<lifetime::heap>, T>();
}

} // namespace basic

inline char16_t
at(const JSString *const &s,
   const size_t &pos)
{
	char16_t ret;
	if(unlikely(!JS_GetStringCharAt(*cx, const_cast<JSString *>(s), pos, &ret)))
		throw range_error("index %zu is out of range", pos);

	return ret;
}

inline size_t
size(const JSString *const &s)
{
	return JS_GetStringLength(const_cast<JSString *>(s));
}

inline bool
external(const JSString *const &s)
{
	return JS_IsExternalString(const_cast<JSString *>(s));
}

} // namespace js
} // namespace ircd