f = {
	args_default = {
		bracket_left = "",
		bracket_right = "",
		bracket_year_left = "",
		bracket_year_right = "",
		postscript = "",
		page = "",
		pages = "",
		location = "",
		page_sep = ", ப. ",
		pages_sep = ", ப. ",
		ref = "",
		P1 = "",
		P2 = "",
		P3 = "",
		P4 = "",
		P5 = ""
	}
};

function trim( str )
	if str == nil then
		return nil;
	end
	return str:match( "^%s*(.-)%s*$");
end    

function core( args )
	local result;

	if args.P5 ~= "" then
		result = args.P1 .. ' et al. ' .. args.bracket_year_left .. args.P5 .. 
		args.bracket_year_right;
	elseif args.P4 ~= "" then
		result = args.P1 .. ', ' .. args.P2 .. ' & ' .. args.P3 .. ' ' .. 
		args.bracket_year_left .. args.P4 .. args.bracket_year_right;
	elseif args.P3 ~= "" then
		result = args.P1 .. ' & ' .. args.P2 .. ' ' .. args.bracket_year_left .. 
		args.P3 .. args.bracket_year_right;
	else
		result = trim( args.P1 .. ' ' .. args.bracket_year_left .. args.P2 .. 
		args.bracket_year_right )
	end

	if args.ref ~= 'none' then
		if args.ref ~= "" then
			result = "[[#" .. mw.uri.anchorEncode(args.ref) .. "|" .. result .. "]]";
		else
			result = "[[#CITEREF" .. mw.uri.anchorEncode(args.P1 .. args.P2 .. args.P3 .. args.P4 .. args.P5) .. "|" .. result .. "]]";
		end
	end

	if args.page ~= "" then
		result = result .. args.page_sep .. args.page;
	elseif args.pages ~= "" then
		result = result .. args.pages_sep .. args.pages;
	end      

	if args.location ~= "" then
		result = result .. ", " .. args.location;
	end

	result = args.bracket_left .. result .. args.bracket_right .. args.postscript;
	return result;
end

function f.harvard_core( frame )
	local args = {};
	local pframe = frame:getParent();

	args.bracket_left = pframe.args.BracketLeft or "";
	args.bracket_right = pframe.args.BracketRight or "";
	args.bracket_year_left = pframe.args.BracketYearLeft or "";
	args.bracket_year_right = pframe.args.BracketYearRight or "";
	args.postscript = pframe.args.Postscript or "";
	if 'none' == args.postscript then
		args.postscript = '';
	end

	args.page = pframe.args.Page or "";
	args.pages = pframe.args.Pages or "";
	args.location = pframe.args.Location or "";
	args.page_sep = pframe.args.PageSep or "";
	args.pages_sep = pframe.args.PagesSep or "";
	args.ref = pframe.args.REF or "{{{REF}}}";
	args.P1 = trim( pframe.args.P1 ) or "";
	args.P2 = trim( pframe.args.P2 ) or "";
	args.P3 = trim( pframe.args.P3 ) or "";
	args.P4 = trim( pframe.args.P4 ) or "";
	args.P5 = trim( pframe.args.P5 ) or "";

	return core( args );
end

function f.harvard_citation( frame )
	local args = f.args_default;
	pframe = frame:getParent();

	args.bracket_left = "(";
	args.bracket_right = ")";
	args.page = pframe.args.p or pframe.args.page or "";
	args.pages = pframe.args.pp or pframe.args.pages or "";
	args.location = pframe.args.loc or "";
	args.ref = pframe.args.ref or pframe.args.Ref or "";
	args.P1 = trim( pframe.args[1] ) or "";
	args.P2 = trim( pframe.args[2] ) or "";
	args.P3 = trim( pframe.args[3] ) or "";
	args.P4 = trim( pframe.args[4] ) or "";
	args.P5 = trim( pframe.args[5] ) or "";

	return core( args );
end

function f.harvard_citation_no_bracket( frame )
	local args = f.args_default;
	pframe = frame:getParent();

	args.page = pframe.args.p or pframe.args.page or "";
	args.pages = pframe.args.pp or pframe.args.pages or "";
	args.location = pframe.args.loc or "";
	args.ref = pframe.args.ref or pframe.args.Ref or "";
	args.P1 = trim( pframe.args[1] ) or "";
	args.P2 = trim( pframe.args[2] ) or "";
	args.P3 = trim( pframe.args[3] ) or "";
	args.P4 = trim( pframe.args[4] ) or "";
	args.P5 = trim( pframe.args[5] ) or "";

	return core( args );
end

function f.sfn( frame )
	local args = f.args_default;
	for k, v in pairs( frame.args ) do											-- for {{sfnp}}, override default with values provided in the #invoke:
		args[k] = v;	   
	end
	
	pframe = frame:getParent();

	args.postscript = pframe.args.postscript or pframe.args.ps or ".";
	if 'none' == args.postscript then
		args.postscript = '';
	end
	args.page = pframe.args.p or pframe.args.page or "";
	args.pages = pframe.args.pp or pframe.args.pages or "";
	args.location = pframe.args.loc or "";
	args.ref = pframe.args.ref or pframe.args.Ref or "";
	args.P1 = trim( pframe.args[1] ) or "";
	args.P2 = trim( pframe.args[2] ) or "";
	args.P3 = trim( pframe.args[3] ) or "";
	args.P4 = trim( pframe.args[4] ) or "";
	args.P5 = trim( pframe.args[5] ) or "";

	local result = core( args );
	local name = "FOOTNOTE" .. args.P1 .. args.P2 .. 
	args.P3 .. args.P4 .. args.P5 .. args.page .. args.pages .. args.location;

	result = frame:extensionTag{ name = "ref", args = {name=name}, content=result };

	return result;
end

return f;