# CURL Extern Type, reproduce CURL low level behaviors
extern class NativeCurl `{ CURL * `}
	# Constructor, CURL low level initializer
	new easy_init `{ return curl_easy_init(); `}

	# Check for correct initialization
	fun is_init: Bool `{ return (self != NULL); `}

	# Easy Clean / Release CURL instance
	fun easy_clean `{ curl_easy_cleanup( self ); `}

	# Perform the transfer described by setted options
	fun easy_perform: CURLCode `{ return curl_easy_perform( self ); `}

	# Set options to tell CURL how to behave. Obj parameter type can be Int, Bool, String, FileWriter, CURLSList.
	fun easy_setopt(opt: CURLOption, obj: Object): CURLCode
	do
		if obj isa Int then return native_setopt_int(opt, obj)
		if obj == true then return native_setopt_int(opt, 1)
		if obj == false then return native_setopt_int(opt, 0)
		if obj isa String then return native_setopt_string(opt, obj.to_cstring)
		if obj isa FileWriter then return native_setopt_file(opt, obj._file.as(not null))
		if obj isa CURLSList then return native_setopt_slist(opt, obj)
		return once new CURLCode.unknown_option
	end

	# Internal method to set options to CURL using NativeFile parameter.
	private fun native_setopt_file(opt: CURLOption, file: NativeFile): CURLCode `{
		return curl_easy_setopt( self, opt, file);
	`}

	# Internal method to set options to CURL using Int parameter.
	private fun native_setopt_int(opt: CURLOption, num: Int): CURLCode `{ return curl_easy_setopt( self, opt, num); `}

	# Internal method to set options to CURL using CURLSList parameter.
	private fun native_setopt_slist(opt: CURLOption, list: CURLSList): CURLCode `{ return curl_easy_setopt( self, opt, list); `}

	# Internal method to set options to CURL using String parameter.
	private fun native_setopt_string(opt: CURLOption, str: CString): CURLCode `{
		return curl_easy_setopt( self, opt, str);
	`}

	# Request Chars internal information from the CURL session
	fun easy_getinfo_chars(opt: CURLInfoChars): nullable String
	do
		 var answ = new Ref[CString]("".to_cstring)
		 if not native_getinfo_chars(opt, answ).is_ok then return null
		 if answ.item.address_is_null then return null
		 return answ.item.to_s
	end

	# Internal method used to get String object information initially known as C Chars type
	private fun native_getinfo_chars(opt: CURLInfoChars, res: Ref[CString]): CURLCode
	import Ref[CString].item= `{
		char *r;
		CURLcode c = curl_easy_getinfo( self, opt, &r);
		if (c == CURLE_OK) Ref_of_CString_item__assign(res, r);
		return c;
	`}

	# Request Long internal information from the CURL session
	fun easy_getinfo_long(opt: CURLInfoLong): nullable Int
	do
		 var answ = new Ref[Int](0)
		 if not native_getinfo_long(opt, answ).is_ok then return null
		 return answ.item
	end

	# Internal method used to get Int object information initially knowns as C Long type
	private fun native_getinfo_long(opt: CURLInfoLong, res: Ref[Int]): CURLCode
	import Ref[Int].item= `{
		long r;
		CURLcode c = curl_easy_getinfo( self, opt, &r);
		if (c == CURLE_OK) Ref_of_Int_item__assign(res, r);
		return c;
	`}

	# Request Double internal information from the CURL session
	fun easy_getinfo_double(opt: CURLInfoDouble): nullable Float
	do
		 var answ = new Ref[Float](0.0)
		 if not native_getinfo_double(opt, answ).is_ok then return null
		 return answ.item
	end

	# Internal method used to get Int object information initially knowns as C Double type
	private fun native_getinfo_double(opt: CURLInfoDouble, res: Ref[Float]): CURLCode
	import Ref[Float].item= `{
		double r;
		CURLcode c = curl_easy_getinfo(self, opt, &r);
		if (c == CURLE_OK) Ref_of_Float_item__assign(res, r);
		return c;
	`}

	# Request SList internal information from the CURL session
	fun easy_getinfo_slist(opt: CURLInfoSList): nullable Array[String]
	do
		var answ = new Ref[CURLSList](new CURLSList)
		if not native_getinfo_slist(opt, answ).is_ok then return null

		var native = answ.item
		var nity = native.to_a
		native.destroy
		return nity
	end

	# Internal method used to get Array[String] object information initially knowns as C SList type
	private fun native_getinfo_slist(opt: CURLInfoSList, res: Ref[CURLSList]): CURLCode
	import Ref[CURLSList].item= `{
		struct curl_slist* csl;
		CURLcode c = curl_easy_getinfo(self, opt, &csl);
		if (c == CURLE_OK) Ref_of_CURLSList_item__assign(res, csl);
		return c;
	`}

	# Register delegate to read datas from given buffer
	fun register_read_datas_callback(delegate: NativeCurlCallbacks, datas: String): CURLCode
	do
		if datas.length > 0 then return native_register_read_datas_callback(delegate, datas, datas.length)
		return once new CURLCode.unknown_option
	end

	# Internal method used to configure read callback
	private fun native_register_read_datas_callback(delegate: NativeCurlCallbacks, datas: String, size: Int): CURLCode import String.to_cstring `{
		CURLCallbackReadDatas *d = NULL;
		d = malloc(sizeof(CURLCallbackReadDatas));
		d->data = (char*)String_to_cstring(datas);
		d->len = size;
		d->pos = 0;
		return curl_easy_setopt( self, CURLOPT_READDATA, d);
	`}

	# Register `delegate` to get callbacks about the CURL transfer
	fun register_callback_header(delegate: NativeCurlCallbacks): CURLCode
	import CString.native_callback_header `{
		CURLcode e;
		NativeCurlCallbacks_incr_ref(delegate); // FIXME deallocated these when download completes?

		e = curl_easy_setopt(self, CURLOPT_HEADERFUNCTION, (curl_write_callback)&CString_native_callback_header);
		if(e != CURLE_OK) return e;

		e = curl_easy_setopt(self, CURLOPT_WRITEHEADER, delegate);
		return e;
	`}

	# Register `delegate` to get callbacks about the CURL transfer
	fun register_callback_body(delegate: NativeCurlCallbacks): CURLCode
	import CString.native_callback_body `{
		CURLcode e;
		NativeCurlCallbacks_incr_ref(delegate);

		e = curl_easy_setopt(self, CURLOPT_WRITEFUNCTION, (curl_write_callback)&CString_native_callback_body);
		if(e != CURLE_OK) return e;

		e = curl_easy_setopt(self, CURLOPT_WRITEDATA, delegate);
		return e;
	`}

	# Register `delegate` to get callbacks about the CURL transfer
	fun register_callback_stream(delegate: NativeCurlCallbacks): CURLCode
	import CString.native_callback_stream `{
		CURLcode e;
		NativeCurlCallbacks_incr_ref(delegate);

		e = curl_easy_setopt(self, CURLOPT_WRITEFUNCTION, (curl_write_callback)&CString_native_callback_stream);
		if(e != CURLE_OK) return e;

		e = curl_easy_setopt(self, CURLOPT_WRITEDATA, delegate);
		return e;
	`}

	# Register `delegate` to get callbacks about the CURL transfer
	fun register_callback_read(delegate: NativeCurlCallbacks): CURLCode
	import CString.native_callback_stream `{
		NativeCurlCallbacks_incr_ref(delegate);

		return curl_easy_setopt(self, CURLOPT_READFUNCTION, (curl_write_callback)&nit_curl_callback_read_func);
	`}

	# Convert given string to URL encoded string
	fun escape(url: String): String import String.to_cstring, CString.to_s `{
		char *orig_url, *encoded_url = NULL;
		orig_url = String_to_cstring(url);
		encoded_url = curl_easy_escape( self, orig_url, strlen(orig_url));
		String b_url = CString_to_s(encoded_url);
		curl_free(encoded_url);
		return b_url;
	`}
end