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module;
#include <boost/json.hpp>
#include <boost/system/system_error.hpp>
module routemon:config$impl;
import std;
import :config;
import :log;
import :util;
namespace json = boost::json;
namespace routemon::config {
class location {
std::optional<std::pair<std::string_view, util::not_null<location const*>>> next_;
auto append_to(std::string& s) const -> void {
if (next_) {
s += next_->first;
s += ".";
next_->second->append_to(s);
}
}
public:
location() = default;
explicit location(location const& next, std::string_view entry)
: next_{std::make_pair(entry, util::not_null{&next})}
{}
[[nodiscard]] auto to_string() const -> std::string {
if (!next_)
return "";
auto s = std::string{next_->first};
next_->second->append_to(s);
return s;
}
auto sub(std::string_view entry) const& -> location {
return location{*this, entry};
}
};
class object_reader {
location loc_;
json::object const& obj_;
std::unordered_set<std::string> visited_;
public:
object_reader(json::value const& jv, location loc)
try : loc_{std::move(loc)}, obj_{jv.as_object()}
{} catch (boost::system::system_error const&) {
throw std::runtime_error{std::format("expected an object at {}", loc.to_string())};
}
auto check_unused() const -> void {
for (auto const& kv : obj_) {
if (!visited_.contains(std::string{kv.key()})) {
throw std::runtime_error{std::format("unexpected key {}", loc_.sub(kv.key()).to_string())};
}
}
}
template<class T>
auto expect_at(std::string_view key) -> T {
visited_.emplace(key);
auto const loc = loc_.sub(key);
if (auto const jv = obj_.try_at(key)) {
try {
return json::value_to<T>(*jv, loc);
} catch (boost::system::system_error const& e) {
throw std::runtime_error{std::format("failed to read {}: {}", loc.to_string(), e.code().message())};
}
} else {
throw std::runtime_error{std::format("did not find expected key {}", loc.to_string())};
}
}
};
auto as_checked_object(json::value const& jv, location const& loc, std::invocable<object_reader&> auto const& f) -> decltype(f(std::declval<object_reader&>())) {
auto r = object_reader{jv, loc};
auto&& v = f(r);
r.check_unused();
return std::forward<decltype(f(r))>(v);
}
auto tag_invoke(json::value_to_tag<rwgps> const&, json::value const& jv, location const& loc) -> rwgps {
return as_checked_object(jv, loc, [](object_reader& r) -> rwgps {
return {
.api_key = r.expect_at<std::string>("api_key"),
.auth_token = r.expect_at<std::string>("auth_token"),
};
});
}
auto tag_invoke(json::value_to_tag<situations> const&, json::value const& jv, location const& loc) -> situations {
return as_checked_object(jv, loc, [](object_reader& r) -> situations {
return {
.datex2_filename = r.expect_at<std::string>("datex2_filename"),
};
});
}
auto tag_invoke(json::value_to_tag<database> const&, json::value const& jv, location const& loc) -> database {
return as_checked_object(jv, loc, [](object_reader& r) -> database {
return {
.sqlite3_filename = r.expect_at<std::string>("sqlite3_filename"),
};
});
}
auto tag_invoke(json::value_to_tag<http_server> const&, json::value const& jv, location const& loc) -> http_server {
return as_checked_object(jv, loc, [](object_reader& r) -> http_server {
return {
.lax_cors = r.expect_at<bool>("lax_cors"),
};
});
}
auto tag_invoke(json::value_to_tag<logger> const&, json::value const& jv, location const& loc) -> logger {
return as_checked_object(jv, loc, [obj_loc = loc](object_reader& r) -> logger {
auto const level_str = r.expect_at<std::string>("level");
auto level = log::level{};
if (level_str == "debug")
level = log::level::debug;
else if (level_str == "info")
level = log::level::info;
else if (level_str == "warn")
level = log::level::warn;
else if (level_str == "error")
level = log::level::error;
else
throw std::runtime_error{std::format("unable to parse log level {:?} at {}: expected one of {{debug, info, warn, error}}", level_str, obj_loc.sub("level").to_string())};
return logger{level};
});
}
auto json_value_to_app(json::value const& jv) -> app {
return as_checked_object(jv, location{}, [](object_reader& r) -> app {
return {
.rwgps = r.expect_at<rwgps>("rwgps"),
.situations = r.expect_at<situations>("situations"),
.database = r.expect_at<database>("database"),
.http_server = r.expect_at<http_server>("http_server"),
.logger = r.expect_at<logger>("logger"),
};
});
}
auto load_file(std::string const& filename) -> app {
auto f = std::ifstream{filename}; // TODO: ensure that we are opening in binary mode?
if (!f.is_open())
throw std::runtime_error{std::format("failed to open {}", filename)};
auto jv = json::value{};
try {
jv = json::parse(f);
} catch (boost::system::system_error const& e) {
throw std::runtime_error{std::format("failed to parse: {}", e.code().message())};
}
return json_value_to_app(jv);
}
} // namespace routemon::config
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