local resolve_relative_path = require "core.configmanager".resolve_relative_path;

local logger = require "util.logger".init;

local set = require "util.set";

local add_filter = require "util.filters".add_filter;

zones = {};

local zones = zones;

setmetatable(zones, {

	__index = function (zones, zone)

		local t = { [zone] = true };

		rawset(zones, zone, t);

		return t;

	end;

});

local chains = {

	preroute = {

		type = "event";

		priority = 0.1;

		"pre-message/bare", "pre-message/full", "pre-message/host";

		"pre-presence/bare", "pre-presence/full", "pre-presence/host";

		"pre-iq/bare", "pre-iq/full", "pre-iq/host";

	};

	deliver = {

		type = "event";

		priority = 0.1;

		"message/bare", "message/full", "message/host";

		"presence/bare", "presence/full", "presence/host";

		"iq/bare", "iq/full", "iq/host";

	};

	deliver_remote = {

		type = "event"; "route/remote";

		priority = 0.1;

	};

};

-- Dependency locations:

-- <type lib>

-- <type global>

-- function handler()

--   <local deps>

--   if <conditions> then

--     <actions>

--   end

-- end

local available_deps = {

	st = { global_code = [[local st = require "util.stanza"]]};

	jid_split = {

		global_code = [[local jid_split = require "util.jid".split;]];

	};

	jid_bare = {

		global_code = [[local jid_bare = require "util.jid".bare;]];

	};

	to = { local_code = [[local to = stanza.attr.to;]] };

	from = { local_code = [[local from = stanza.attr.from;]] };

	type = { local_code = [[local type = stanza.attr.type;]] };

	name = { local_code = [[local name = stanza.name]] };

	split_to = { -- The stanza's split to address

		depends = { "jid_split", "to" };

		local_code = [[local to_node, to_host, to_resource = jid_split(to);]];

	};

	split_from = { -- The stanza's split from address

		depends = { "jid_split", "from" };

		local_code = [[local from_node, from_host, from_resource = jid_split(from);]];

	};

	bare_to = { depends = { "jid_bare", "to" }, local_code = "local bare_to = jid_bare(to)"};

	bare_from = { depends = { "jid_bare", "from" }, local_code = "local bare_from = jid_bare(from)"};

	group_contains = {

		global_code = [[local group_contains = module:depends("groups").group_contains]];

	};

	is_admin = { global_code = [[local is_admin = require "core.usermanager".is_admin]]};

	core_post_stanza = { global_code = [[local core_post_stanza = prosody.core_post_stanza]] };

};

local function include_dep(dep, code)

	local dep_info = available_deps[dep];

	if not dep_info then

		module:log("error", "Dependency not found: %s", dep);

		return;

	end

	if code.included_deps[dep] then

		if code.included_deps[dep] ~= true then

			module:log("error", "Circular dependency on %s", dep);

		end

		return;

	end

	code.included_deps[dep] = false; -- Pending flag (used to detect circular references)

	for _, dep_dep in ipairs(dep_info.depends or {}) do

		include_dep(dep_dep, code);

	end

	if dep_info.global_code then

		table.insert(code.global_header, dep_info.global_code);

	end

	if dep_info.local_code then

		table.insert(code, "\n\t-- "..dep.."\n\t"..dep_info.local_code.."\n\n\t");

	end

	code.included_deps[dep] = true;

end

local condition_handlers = module:require("conditions");

local action_handlers = module:require("actions");

local function new_rule(ruleset, chain)

	assert(chain, "no chain specified");

	local rule = { conditions = {}, actions = {}, deps = {} };

	table.insert(ruleset[chain], rule);

	return rule;

end

local function compile_firewall_rules(filename)

	local line_no = 0;

	local ruleset = {

		deliver = {};

	};

	local chain = "deliver"; -- Default chain

	local rule;

	local file, err = io.open(filename);

	if not file then return nil, err; end

	local state; -- nil -> "rules" -> "actions" -> nil -> ...

	local line_hold;

	for line in file:lines() do

		line = line:match("^%s*(.-)%s*$");

		if line_hold and line:sub(-1,-1) ~= "\\" then

			line = line_hold..line;

			line_hold = nil;

		elseif line:sub(-1,-1) == "\\" then

			line_hold = (line_hold or "")..line:sub(1,-2);

		end

		line_no = line_no + 1;

		if line_hold or line:match("^[#;]") then

			-- No action; comment or partial line

		elseif line == "" then

			if state == "rules" then

				return nil, ("Expected an action on line %d for preceding criteria")

					:format(line_no);

			end

			state = nil;

		elseif not(state) and line:match("^::") then

			chain = line:gsub("^::%s*", "");

			ruleset[chain] = ruleset[chain] or {};

		elseif not(state) and line:match("^ZONE ") then

			local zone_name = line:match("^ZONE ([^:]+)");

			local zone_members = line:match("^ZONE .-: ?(.*)");

			local zone_member_list = {};

			for member in zone_members:gmatch("[^, ]+") do

				zone_member_list[#zone_member_list+1] = member;

			end

			zones[zone_name] = set.new(zone_member_list)._items;

		elseif line:match("^[^%s:]+[%.=]") then

			-- Action

			if state == nil then

				-- This is a standalone action with no conditions

				rule = new_rule(ruleset, chain);

			end

			state = "actions";

			-- Action handlers?

			local action = line:match("^%P+");

			if not action_handlers[action] then

				return nil, ("Unknown action on line %d: %s"):format(line_no, action or "<unknown>");

			end

			table.insert(rule.actions, "-- "..line)

			local action_string, action_deps = action_handlers[action](line:match("=(.+)$"));

			table.insert(rule.actions, action_string);

			for _, dep in ipairs(action_deps or {}) do

				table.insert(rule.deps, dep);

			end

		elseif state == "actions" then -- state is actions but action pattern did not match

			state = nil; -- Awaiting next rule, etc.

			table.insert(ruleset[chain], rule);

			rule = nil;

		else

			if not state then

				state = "rules";

				rule = new_rule(ruleset, chain);

			end

			-- Check standard modifiers for the condition (e.g. NOT)

			local negated;

			local condition = line:match("^[^:=%.]*");

			if condition:match("%f[%w]NOT%f[^%w]") then

				local s, e = condition:match("%f[%w]()NOT()%f[^%w]");

				condition = (condition:sub(1,s-1)..condition:sub(e+1, -1)):match("^%s*(.-)%s*$");

				negated = true;

			end

			condition = condition:gsub(" ", "");

			if not condition_handlers[condition] then

				return nil, ("Unknown condition on line %d: %s"):format(line_no, condition);

			end

			-- Get the code for this condition

			local condition_code, condition_deps = condition_handlers[condition](line:match(":%s?(.+)$"));

			if negated then condition_code = "not("..condition_code..")"; end

			table.insert(rule.conditions, condition_code);

			for _, dep in ipairs(condition_deps or {}) do

				table.insert(rule.deps, dep);

			end

		end

	end

	-- Compile ruleset and return complete code

	local chain_handlers = {};

	-- Loop through the chains in the parsed ruleset (e.g. incoming, outgoing)

	for chain_name, rules in pairs(ruleset) do

		local code = { included_deps = {}, global_header = {} };

		-- This inner loop assumes chain is an event-based, not a filter-based

		-- chain (filter-based will be added later)

		for _, rule in ipairs(rules) do

			for _, dep in ipairs(rule.deps) do

				include_dep(dep, code);

			end

			local rule_code = "if ("..table.concat(rule.conditions, ") and (")..") then\n\t"

			..table.concat(rule.actions, "\n\t")

			.."\n end\n";

			table.insert(code, rule_code);

		end

		assert(chains[chain_name].type == "event", "Only event chains supported at the moment")

		local code_string = [[return function (zones, log)

			]]..table.concat(code.global_header, "\n")..[[

			local db = require 'util.debug'

			return function (event)

				local stanza, session = event.stanza, event.origin;

				]]..table.concat(code, " ")..[[

			end;

		end]];

		print(code_string)

		-- Prepare event handler function

		local chunk, err = loadstring(code_string, "="..filename);

		if not chunk then

			return nil, "Error compiling (probably a compiler bug, please report): "..err;

		end

		chunk = chunk()(zones, logger(filename)); -- Returns event handler with 'zones' upvalue.

		chain_handlers[chain_name] = chunk;

	end

	return chain_handlers;

end

function module.load()

	local firewall_scripts = module:get_option_set("firewall_scripts", {});

	for script in firewall_scripts do

		local chain_functions, err = compile_firewall_rules(script)

		if not chain_functions then

			module:log("error", "Error compiling %s: %s", script, err or "unknown error");

		else

			for chain, handler in pairs(chain_functions) do

				local chain_definition = chains[chain];

				if chain_definition.type == "event" then

					for _, event_name in ipairs(chain_definition) do

						module:hook(event_name, handler, chain_definition.priority);

					end

				end

			end

		end

	end

end