local id = require "util.id";

-- Library configuration (see configure())

local auto_inject_traceback = false;

local display_tracebacks = false;

local error_mt = { __name = "error" };

function error_mt:__tostring()

	if display_tracebacks and self.context.traceback then

		return ("error<%s:%s:%s:%s>"):format(self.type, self.condition, self.text or "", self.context.traceback);

	end

	return ("error<%s:%s:%s>"):format(self.type, self.condition, self.text or "");

end

local function is_err(e)

	return getmetatable(e) == error_mt;

end

local function configure(opt)

	if opt.display_tracebacks ~= nil then

		display_tracebacks = opt.display_tracebacks;

	end

	if opt.auto_inject_traceback ~= nil then

		auto_inject_traceback = opt.auto_inject_traceback;

	end

end

-- Do we want any more well-known fields?

-- Or could we just copy all fields from `e`?

-- Sometimes you want variable details in the `text`, how to handle that?

-- Translations?

-- Should the `type` be restricted to the stanza error types or free-form?

-- What to set `type` to for stream errors or SASL errors? Those don't have a 'type' attr.

local function new(e, context, registry, source)

	local template = (registry and registry[e]) or e or {};

	context = context or {};

	if auto_inject_traceback then

		context.traceback = debug.traceback("error stack", 2);

	end

		instance_id = id.short();

		type = template.type or "cancel";

		condition = template.condition or "undefined-condition";

		text = template.text;

		code = template.code;

		source = source;

	}, error_mt);

end

local function init(source, registry)

	return function (e, context)

		return new(e, context, registry, source);

	end

end

local function coerce(ok, err, ...)

	if ok or is_err(err) then

		return ok, err, ...;

	end

	local new_err = setmetatable({

		native = err;

		type = "cancel";

		condition = "undefined-condition";

	}, error_mt);

	return ok, new_err, ...;

end

local function from_stanza(stanza, context)

	local error_type, condition, text = stanza:get_error();

	return setmetatable({

		type = error_type or "cancel";

		condition = condition or "undefined-condition";

		text = text;

		context = context or { stanza = stanza };

	}, error_mt);

end

return {

	new = new;

	init = init;

	coerce = coerce;

	is_err = is_err;

	from_stanza = from_stanza;

	configure = configure;

}