module metrics

import sync.stdatomic

struct Counter {
	metric Metric
	data   u64
}

struct FloatSeries {
	metric Metric
pub mut:
	data shared []f64
}

[heap]
struct DefaultCollector {
mut:
	counters   shared map[string]&Counter
	histograms shared map[string]&FloatSeries
	gauges     shared map[string]&FloatSeries
}

pub fn new_default_collector() &DefaultCollector {
	return &DefaultCollector{
		counters: map[string]&Counter{}
		histograms: map[string]&FloatSeries{}
		gauges: map[string]&FloatSeries{}
	}
}

pub fn (mut c DefaultCollector) counter_register(value u64, metric Metric) {
	lock c.counters {
		c.counters[metric.str()] = &Counter{
			metric: metric
			data: value
		}
	}
}

pub fn (c &DefaultCollector) counter_increment(metric Metric) {
	rlock c.counters {
		entry := c.counters[metric.str()]

		stdatomic.add_u64(&entry.data, 1)
	}
}

pub fn (c &DefaultCollector) counter_get(metric Metric) ?u64 {
	return rlock c.counters {
		entry := c.counters[metric.str()] or { return none }

		stdatomic.load_u64(&entry.data)
	}
}

pub fn (c &DefaultCollector) counters() []Metric {
	mut metrics := []Metric{}

	rlock c.counters {
		for _, entry in c.counters {
			metrics << entry.metric
		}
	}

	return metrics
}

pub fn (mut c DefaultCollector) histogram_register(metric Metric) {
	lock c.histograms {
		c.histograms[metric.str()] = &FloatSeries{
			metric: metric
			data: []f64{}
		}
	}
}

pub fn (c &DefaultCollector) histogram_record(value f64, metric Metric) {
	entry := rlock c.histograms {
		c.histograms[metric.str()]
	}

	lock entry.data {
		entry.data << value
	}
}

pub fn (c &DefaultCollector) histogram_get(metric Metric) ?[]f64 {
	entry := rlock c.histograms {
		c.histograms[metric.str()] or { return none }
	}

	return rlock entry.data {
		// Return a clone of the data to prevent user from altering
		// internal structure
		entry.data.clone()
	}
}

pub fn (mut c DefaultCollector) gauge_register(value f64, metric Metric) {
	lock c.gauges {
		c.gauges[metric.str()] = &FloatSeries{
			metric: metric
			data: [value]
		}
	}
}

pub fn (c &DefaultCollector) gauge_add(value f64, metric Metric) {
	entry := rlock c.gauges {
		c.gauges[metric.str()]
	}

	lock entry.data {
		entry.data[0] += value
	}
}

pub fn (c &DefaultCollector) gauge_sub(value f64, metric Metric) {
	entry := rlock c.gauges {
		c.gauges[metric.str()]
	}

	lock entry.data {
		entry.data[0] -= value
	}
}

pub fn (c &DefaultCollector) gauge_set(value f64, metric Metric) {
	entry := rlock c.gauges {
		c.gauges[metric.str()]
	}

	lock entry.data {
		entry.data[0] = value
	}
}

pub fn (c &DefaultCollector) gauge_get(metric Metric) ?f64 {
	entry := rlock c.gauges {
		c.gauges[metric.str()]
	}

	return rlock entry.data {
		entry.data[0]
	}
}