"""Application metrics are defined here."""

from dataclasses import dataclass

from opentelemetry import metrics
from opentelemetry.sdk.metrics import Counter, Histogram


@dataclass
class HTTPMetrics:
    request_processing_duration: Histogram
    """Processing time histogram in seconds by `["method", "path"]`."""
    requests_started: Counter
    """Total started requests counter by `["method", "path"]`."""
    requests_finished: Counter
    """Total finished requests counter by `["method", "path", "status_code"]`."""
    errors: Counter
    """Total errors (exceptions) counter by `["method", "path", "error_type", "status_code"]`."""


@dataclass
class Metrics:
    http: HTTPMetrics


def init_metrics() -> Metrics:
    meter = metrics.get_meter("{{project_name}}")
    return Metrics(
        http=HTTPMetrics(
            request_processing_duration=meter.create_histogram(
                "request_processing_duration",
                "sec",
                "Request processing duration time in seconds",
                explicit_bucket_boundaries_advisory=[
                    0.05,
                    0.2,
                    0.3,
                    0.7,
                    1.0,
                    1.5,
                    2.5,
                    5.0,
                    10.0,
                    20.0,
                    40.0,
                    60.0,
                    120.0,
                ],
            ),
            requests_started=meter.create_counter("requests_started_total", "1", "Total number of started requests"),
            requests_finished=meter.create_counter("request_finished_total", "1", "Total number of finished requests"),
            errors=meter.create_counter("request_errors_total", "1", "Total number of errors (exceptions) in requests"),
        )
    )