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 'chat') 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

return condition_handlers;