local condition_handlers = {};

local jid = require "util.jid";

-- Return a code string for a condition that checks whether the contents

-- of variable with the name 'name' matches any of the values in the

-- comma/space/pipe delimited list 'values'.

local function compile_comparison_list(name, values)

	local conditions = {};

	for value in values:gmatch("[^%s,|]+") do

		table.insert(conditions, ("%s == %q"):format(name, value));

	end

	return table.concat(conditions, " or ");

end

function condition_handlers.KIND(kind)

	return compile_comparison_list("name", kind), { "name" };

end

local wildcard_equivs = { ["*"] = ".*", ["?"] = "." };

local function compile_jid_match_part(part, match)

	if not match then

		return part.." == nil"

	end

	local pattern = match:match("<(.*)>");

	if pattern then

		if pattern == "*" then

			return part;

		end

		if pattern:match("^<.*>$") then

			pattern = pattern:match("^<(.*)>$");

		else

			pattern = pattern:gsub("%p", "%%%0"):gsub("%%(%p)", wildcard_equivs);

		end

		return ("%s:match(%q)"):format(part, "^"..pattern.."$");

	else

		return ("%s == %q"):format(part, match);

	end

end

local function compile_jid_match(which, match_jid)

	local match_node, match_host, match_resource = jid.split(match_jid);

	local conditions = {};

	conditions[#conditions+1] = compile_jid_match_part(which.."_node", match_node);

	conditions[#conditions+1] = compile_jid_match_part(which.."_host", match_host);

	if match_resource then

		conditions[#conditions+1] = compile_jid_match_part(which.."_resource", match_resource);

	end

	return table.concat(conditions, " and ");

end

function condition_handlers.TO(to)

	return compile_jid_match("to", to), { "split_to" };

end

function condition_handlers.FROM(from)

	return compile_jid_match("from", from), { "split_from" };

end

function condition_handlers.TYPE(type)

	return compile_comparison_list("(type or (name == 'message' and 'normal') or (name == 'presence' and 'available'))", type), { "type", "name" };

end

local function zone_check(zone, which)

	local which_not = which == "from" and "to" or "from";

	return ("(zone_%s[%s_host] or zone_%s[%s] or zone_%s[bare_%s]) "

		.."and not(zone_%s[%s_host] or zone_%s[%s] or zone_%s[%s])"

		)

		:format(zone, which, zone, which, zone, which,

		zone, which_not, zone, which_not, zone, which_not), {

			"split_to", "split_from", "bare_to", "bare_from", "zone:"..zone

		};

end

function condition_handlers.ENTERING(zone)

	return zone_check(zone, "to");

end

function condition_handlers.LEAVING(zone)

	return zone_check(zone, "from");

end

function condition_handlers.PAYLOAD(payload_ns)

	return ("stanza:get_child(nil, %q)"):format(payload_ns);

end

function condition_handlers.INSPECT(path)

	if path:find("=") then

		local path, match = path:match("(.-)=(.*)");

		return ("stanza:find(%q) == %q"):format(path, match);

	end

	return ("stanza:find(%q)"):format(path);

end

function condition_handlers.FROM_GROUP(group_name)

	return ("group_contains(%q, bare_from)"):format(group_name), { "group_contains", "bare_from" };

end

function condition_handlers.TO_GROUP(group_name)

	return ("group_contains(%q, bare_to)"):format(group_name), { "group_contains", "bare_to" };

end

function condition_handlers.FROM_ADMIN_OF(host)

	return ("is_admin(bare_from, %s)"):format(host ~= "*" and host or nil), { "is_admin", "bare_from" };

end

function condition_handlers.TO_ADMIN_OF(host)

	return ("is_admin(bare_to, %s)"):format(host ~= "*" and host or nil), { "is_admin", "bare_to" };

end

local day_numbers = { sun = 0, mon = 2, tue = 3, wed = 4, thu = 5, fri = 6, sat = 7 };

local function current_time_check(op, hour, minute)

	hour, minute = tonumber(hour), tonumber(minute);

	local adj_op = op == "<" and "<" or ">="; -- Start time inclusive, end time exclusive

	if minute == 0 then

		return "(current_hour"..adj_op..hour..")";

	else

		return "((current_hour"..op..hour..") or (current_hour == "..hour.." and current_minute"..adj_op..minute.."))";

	end

end

local function resolve_day_number(day_name)

	return assert(day_numbers[day_name:sub(1,3):lower()], "Unknown day name: "..day_name);

end

function condition_handlers.DAY(days)

	local conditions = {};

	for day_range in days:gmatch("[^,]+") do

		local day_start, day_end = day_range:match("(%a+)%s*%-%s*(%a+)");

		if day_start and day_end then

			local day_start_num, day_end_num = resolve_day_number(day_start), resolve_day_number(day_end);

			local op = "and";

			if day_end_num < day_start_num then

				op = "or";

			end

			table.insert(conditions, ("current_day >= %d %s current_day <= %d"):format(day_start_num, op, day_end_num));

		elseif day_range:match("%a") then

			local day = resolve_day_number(day_range:match("%a+"));

			table.insert(conditions, "current_day == "..day);

		else

			error("Unable to parse day/day range: "..day_range);

		end

	end

	assert(#conditions>0, "Expected a list of days or day ranges");

	return "("..table.concat(conditions, ") or (")..")", { "time:day" };

end

function condition_handlers.TIME(ranges)

	local conditions = {};

	for range in ranges:gmatch("([^,]+)") do

		local clause = {};

		range = range:lower()

			:gsub("(%d+):?(%d*) *am", function (h, m) return tostring(tonumber(h)%12)..":"..(tonumber(m) or "00"); end)

			:gsub("(%d+):?(%d*) *pm", function (h, m) return tostring(tonumber(h)%12+12)..":"..(tonumber(m) or "00"); end);

		local start_hour, start_minute = range:match("(%d+):(%d+) *%-");

		local end_hour, end_minute = range:match("%- *(%d+):(%d+)");

		local op = tonumber(start_hour) > tonumber(end_hour) and " or " or " and ";

		if start_hour and end_hour then

			table.insert(clause, current_time_check(">", start_hour, start_minute));

			table.insert(clause, current_time_check("<", end_hour, end_minute));

		end

		if #clause == 0 then

			error("Unable to parse time range: "..range);

		end

		table.insert(conditions, "("..table.concat(clause, " "..op.." ")..")");

	end

	return table.concat(conditions, " or "), { "time:hour,min" };

end

function condition_handlers.LIMIT(name)

	return ("not throttle_%s:poll(1)"):format(name), { "throttle:"..name };

end

return condition_handlers;