##! Functions for accessing counter metrics from script land.

module Telemetry;

%%{

#include <span>
#include "zeek/telemetry/Counter.h"
#include "zeek/telemetry/Gauge.h"
#include "zeek/telemetry/Histogram.h"
#include "zeek/telemetry/Manager.h"
#include "zeek/telemetry/Opaques.h"

namespace {

template <class ScriptHandle, class Fun>
auto with(zeek::Val* val, const char* error_msg, Fun fun)
	{
	if ( auto ptr = dynamic_cast<ScriptHandle*>(val) )
		{
		fun(ptr->GetHandle());
		return zeek::val_mgr->True();
		}
	else
		{
		zeek::reporter->Error("%s", error_msg);
		return zeek::val_mgr->False();
		}
	}

std::string_view sv(const zeek::String* str) noexcept
	{
	auto len = static_cast<size_t>(str->Len());
	return {reinterpret_cast<char*>(str->Bytes()), len};
	};

std::string_view sv(const zeek::StringVal* val) noexcept
	{
	return sv(val->AsString());
	};

std::vector<std::string_view> sv_vec(zeek::VectorVal* xs)
	{
	std::vector<std::string_view> result;
	if ( xs )
		for ( unsigned index = 0; index < xs->Size(); ++index )
			if ( auto ptr = xs->ValAt(index) )
				if ( auto* str = ptr->AsString() )
					result.emplace_back(sv(str));
	return result;
	}

std::vector<zeek::telemetry::LabelView> sv_tbl(zeek::TableVal* xs)
	{
	std::vector<zeek::telemetry::LabelView> result;
	if ( xs )
		{
		for ( auto& val : *xs->Get() )
			{
			auto val_ptr = val.value->GetVal();
			result.emplace_back(std::string_view{val.GetKey(), val.key_size},
			                    sv(val_ptr->AsStringVal()));
			}
		}
	return result;
	}

bool labels_valid(std::span<const zeek::telemetry::LabelView> labels,
              std::span<const std::string> label_names)
	{
	auto key_in_label_names = [keys{label_names}](auto x)
		{
		return std::find(keys.begin(), keys.end(), x.first) != keys.end();
		};
	return labels.size() == label_names.size()
	       && std::ranges::all_of(labels, key_in_label_names);
	}

template <class IntOrDbl>
auto to_std_vec(zeek::VectorVal* xs)
	{
	std::vector<IntOrDbl> result;
	if( xs )
		for ( unsigned index = 0; index < xs->Size() ; ++index )
			{
			if constexpr (std::is_same_v<IntOrDbl, int64_t>)
				result.emplace_back(xs->ValAt(index)->AsInt());
			else
				result.emplace_back(xs->ValAt(index)->AsDouble());
			}
	return result;
	}

template <class IntOrDbl>
auto to_std_vec(zeek::Val* xs)
	{
	return to_std_vec<IntOrDbl>(xs->AsVectorVal());
	}

}
%%}

# -- Counter ----------------------------------------------------------------

function Telemetry::__counter_family%(prefix: string,
                                          name: string,
                                          labels: string_vec,
                                          helptext: string &default = "Zeek Script Metric",
                                          unit: string &default = ""%): opaque of counter_metric_family
	%{
	auto lbl_vec = sv_vec(labels->AsVectorVal());
	auto hdl = telemetry_mgr->CounterFamily(sv(prefix), sv(name), lbl_vec,
	                                        sv(helptext), sv(unit));
	return zeek::make_intrusive<CounterMetricFamilyVal>(hdl);
	%}

function Telemetry::__counter_metric_get_or_add%(family: opaque of counter_metric_family,
                                                     labels: table_string_of_string%): opaque of counter_metric
	%{
	using ResultType = zeek::IntrusivePtr<CounterMetricFamilyVal>;
	if ( auto ptr = dynamic_cast<zeek::CounterMetricFamilyVal*>(family) )
		{
		auto hdl = ptr->GetHandle();
		auto lbl_map = sv_tbl(labels->AsTableVal());
		if ( labels_valid(lbl_map, hdl->LabelNames()) )
			{
			auto res = hdl->GetOrAdd(lbl_map);
			return zeek::make_intrusive<CounterMetricVal>(res);
			}
		else
			{
			zeek::reporter->Error("Telemetry::counter_metric_get_or_add: invalid label dimensions.");
			return ResultType{nullptr};
			}
		}
	else
		{
		zeek::reporter->Error("Telemetry::counter_metric_get_or_add: invalid handle.");
		return ResultType{nullptr};
		}
	%}

function Telemetry::__counter_inc%(val: opaque of counter_metric,
                                   amount: double &default = 1.0%): bool
	%{
	return with<CounterMetricVal>(val, "Telemetry::counter_inc: invalid handle.", [amount](auto hdl) { hdl->Inc(amount); });
	%}

function Telemetry::__counter_value%(val: opaque of counter_metric%): double
	%{
	if ( auto ptr = dynamic_cast<zeek::CounterMetricVal*>(val) )
		{
		return zeek::make_intrusive<zeek::DoubleVal>(ptr->GetHandle()->Value());
		}
	else
		{
		zeek::reporter->Error("Telemetry::counter_value: invalid handle.");
		return zeek::make_intrusive<zeek::DoubleVal>(0);
		}
	%}

# -- Gauge ------------------------------------------------------------------

function Telemetry::__gauge_family%(prefix: string,
                                        name: string,
                                        labels: string_vec,
                                        helptext: string &default = "Zeek Script Metric",
                                        unit: string &default = ""%): opaque of gauge_metric_family
	%{
	auto lbl_vec = sv_vec(labels->AsVectorVal());
	auto hdl = telemetry_mgr->GaugeFamily(sv(prefix), sv(name), lbl_vec,
	                                        sv(helptext), sv(unit));
	return zeek::make_intrusive<GaugeMetricFamilyVal>(hdl);
	%}

function Telemetry::__gauge_metric_get_or_add%(family: opaque of gauge_metric_family,
                                                   labels: table_string_of_string%): opaque of gauge_metric
	%{
	using ResultType = zeek::IntrusivePtr<GaugeMetricFamilyVal>;
	if ( auto ptr = dynamic_cast<zeek::GaugeMetricFamilyVal*>(family) )
		{
		auto hdl = ptr->GetHandle();
		auto lbl_map = sv_tbl(labels->AsTableVal());
		if ( labels_valid(lbl_map, hdl->LabelNames()) )
			{
			auto res = hdl->GetOrAdd(lbl_map);
			return zeek::make_intrusive<GaugeMetricVal>(res);
			}
		else
			{
			zeek::reporter->Error("Telemetry::gauge_metric_get_or_add: invalid label dimensions.");
			return ResultType{nullptr};
			}
		}
	else
		{
		zeek::reporter->Error("Telemetry::gauge_metric_get_or_add: invalid handle.");
		return ResultType{nullptr};
		}
	%}

function Telemetry::__gauge_inc%(val: opaque of gauge_metric,
                                     amount: double &default = 1.0%): bool
	%{
	return with<GaugeMetricVal>(val, "Telemetry::gauge_inc: invalid handle.", [amount](auto hdl) { hdl->Inc(amount); });
	%}

function Telemetry::__gauge_dec%(val: opaque of gauge_metric,
                                     amount: double &default = 1.0%): bool
	%{
	return with<GaugeMetricVal>(val, "Telemetry::gauge_dec: invalid handle.", [amount](auto hdl) { hdl->Dec(amount); });
	%}

function Telemetry::__gauge_value%(val: opaque of gauge_metric%): double
	%{
	if ( auto ptr = dynamic_cast<zeek::GaugeMetricVal*>(val) )
		{
		return zeek::make_intrusive<zeek::DoubleVal>(ptr->GetHandle()->Value());
		}
	else
		{
		zeek::reporter->Error("Telemetry::gauge_value: invalid handle.");
		return zeek::make_intrusive<zeek::DoubleVal>(0.0);
		}
	%}

# -- Histogram --------------------------------------------------------------

function Telemetry::__histogram_family%(prefix: string,
                                            name: string,
                                            labels: string_vec,
                                            bounds: double_vec,
                                            helptext: string &default = "Zeek Script Metric",
                                            unit: string &default = ""%): opaque of histogram_metric_family
	%{
	auto lbl_vec = sv_vec(labels->AsVectorVal());
	auto std_bounds = to_std_vec<double>(bounds);
	auto hdl = telemetry_mgr->HistogramFamily(sv(prefix), sv(name), lbl_vec,
	                                          std_bounds, sv(helptext),
	                                          sv(unit));
	return zeek::make_intrusive<HistogramMetricFamilyVal>(hdl);
	%}

function Telemetry::__histogram_metric_get_or_add%(family: opaque of histogram_metric_family,
                                                       labels: table_string_of_string%): opaque of histogram_metric
	%{
	using ResultType = zeek::IntrusivePtr<HistogramMetricFamilyVal>;
	if ( auto ptr = dynamic_cast<zeek::HistogramMetricFamilyVal*>(family) )
		{
		auto hdl = ptr->GetHandle();
		auto lbl_map = sv_tbl(labels->AsTableVal());
		if ( labels_valid(lbl_map, hdl->LabelNames()) )
			{
			auto res = hdl->GetOrAdd(lbl_map);
			return zeek::make_intrusive<HistogramMetricVal>(res);
			}
		else
			{
			zeek::reporter->Error("Telemetry::histogram_metric_get_or_add: invalid label dimensions.");
			return ResultType{nullptr};
			}
		}
	else
		{
		zeek::reporter->Error("Telemetry::histogram_metric_get_or_add: invalid handle.");
		return ResultType{nullptr};
		}
	%}

function Telemetry::__histogram_observe%(val: opaque of histogram_metric,
                                         measurement: double%): bool
	%{
	return with<HistogramMetricVal>(val, "Telemetry::histogram_inc: invalid handle.",
                                    [measurement](auto hdl) { hdl->Observe(measurement); });
	%}

function Telemetry::__histogram_sum%(val: opaque of histogram_metric%): double
	%{
	if ( auto ptr = dynamic_cast<zeek::HistogramMetricVal*>(val) )
		{
		return zeek::make_intrusive<zeek::DoubleVal>(ptr->GetHandle()->Sum());
		}
	else
		{
		zeek::reporter->Error("Telemetry::histogram_sum: invalid handle.");
        return make_intrusive<zeek::DoubleVal>(0.0);
		}
	%}

function Telemetry::__collect_metrics%(prefix: string, name: string%): any_vec
	%{
	return telemetry_mgr->CollectMetrics(sv(prefix), sv(name));
	%}

function Telemetry::__collect_histogram_metrics%(prefix: string, name: string%): any_vec
	%{
	return telemetry_mgr->CollectHistogramMetrics(sv(prefix), sv(name));
	%}