DeepTrace/PrometheusAPI/PrometheusClient.cs

using System.Text.Json;

namespace PrometheusAPI;

public class PrometheusClient
{
    private readonly HttpClient _client;

    public PrometheusClient(HttpClient client)
    {
        _client = client;
    }

    public async Task<InstantQueryResponse> InstantQuery(string query, DateTime? time = null, CancellationToken token = default)
    {
        var q = new List<KeyValuePair<string, string>>
        {
            new KeyValuePair<string, string>("query", query)
        };

        if (time != null)
            q.Add(new KeyValuePair<string, string>("time", TimeSeries.DateTimeToUnixTimestamp(time.Value).ToString("F3")));

        var form = new FormUrlEncodedContent(q);

        var response = await _client.PostAsync("/api/v1/query", form);

        var json = await response.Content.ReadAsStringAsync()
            ?? throw new InvalidDataException("Responce is null");

        var res = JsonSerializer.Deserialize<InstantQueryResponse>(json, JsonSetializerSetup.Options)
            ?? throw new InvalidDataException("Can't convert responce to InstantQueryResponse");

        return res;
    }

    public async Task<InstantQueryResponse> RangeQuery(string query, DateTime start, DateTime end, TimeSpan step, TimeSpan timeout = default, CancellationToken token = default)
    {
        var q = new List<KeyValuePair<string, string>>
        {
            new KeyValuePair<string, string>("query", query),
            new KeyValuePair<string, string>("start", TimeSeries.DateTimeToUnixTimestamp(start).ToString("F3")),
            new KeyValuePair<string, string>("end",   TimeSeries.DateTimeToUnixTimestamp(end).ToString("F3")),
            new KeyValuePair<string, string>("step",  step.TotalSeconds.ToString("F3"))
        };

        if( timeout != default )
        {
            q.Add(new KeyValuePair<string, string>("timeout", timeout.TotalSeconds.ToString("F3")));
        }

        var form = new FormUrlEncodedContent(q);

        var response = await _client.PostAsync("/api/v1/query_range", form);

        var json = await response.Content.ReadAsStringAsync()
            ?? throw new InvalidDataException("Responce is null");

        var res = JsonSerializer.Deserialize<InstantQueryResponse>(json, JsonSetializerSetup.Options)
            ?? throw new InvalidDataException("Can't convert responce to InstantQueryResponse");

        return res;
    }

    public async Task<string> FormatQuery(string query, CancellationToken token = default)
    {
        var q = new List<KeyValuePair<string, string>>
        {
            new KeyValuePair<string, string>("query", query),
        };


        var form = new FormUrlEncodedContent(q);

        var response = await _client.PostAsync("/api/v1/format_query", form);

        var json = await response.Content.ReadAsStringAsync()
            ?? throw new InvalidDataException("Responce is null");

        var res = JsonSerializer.Deserialize<JsonDocument>(json, JsonSetializerSetup.Options)
            ?? throw new InvalidDataException("Can't convert responce to JsonDocument");

        var status = res.RootElement.GetProperty("status").GetString()
            ?? throw new InvalidDataException("Can't get status");

        if (!status.Equals("success", StringComparison.OrdinalIgnoreCase) )
            throw new InvalidDataException(res.RootElement.GetProperty("error").GetString());

        var data = res.RootElement.GetProperty("data").GetString()
            ?? throw new InvalidDataException("Can't get formatted query");

        return data;
    }

    public async Task<string[]> GetMetricsNames(CancellationToken token = default)
    {
        var response = await _client.GetAsync("/api/v1/label/__name__/values");

        var json = await response.Content.ReadAsStringAsync()
            ?? throw new InvalidDataException("Responce is null");

        var res = JsonSerializer.Deserialize<JsonDocument>(json, JsonSetializerSetup.Options)
            ?? throw new InvalidDataException("Can't convert responce to JsonDocument");

        var status = res.RootElement.GetProperty("status").GetString()
            ?? throw new InvalidDataException("Can't get status");

        if (!status.Equals("success", StringComparison.OrdinalIgnoreCase))
            throw new InvalidDataException(res.RootElement.GetProperty("error").GetString());

        var data = res.RootElement.GetProperty("data").EnumerateArray().Select(x => x.GetString()).Where( x => x != null).Cast<string>().ToArray<string>()
            ?? throw new InvalidDataException("Can't get formatted query");

        return data;

    }

}