using System.Text.Json;
using GetFromLoki.Models;
using Microsoft.Extensions.Options;

namespace GetFromLoki.Services;

public class LokiService : ILokiService
{
    private readonly HttpClient _httpClient;
    private readonly LokiOptions _options;

    public LokiService(HttpClient httpClient, IOptions<LokiOptions> options)
    {
        _httpClient = httpClient;
        _options = options.Value;
        _httpClient.BaseAddress = new Uri(_options.BaseUrl);
        _httpClient.Timeout = TimeSpan.FromSeconds(_options.QueryTimeout);
    }

    public async Task<List<LogEntry>> GetLogsAsync(LogQueryRequest request)
    {
        var logs = new List<LogEntry>();
        
        // Формируем LogQL запрос
        var query = BuildLogQLQuery(request);
        
        // Формируем URL с параметрами
        var queryParams = new List<string>
        {
            $"query={Uri.EscapeDataString(query)}",
            $"limit={request.Limit ?? 100}"
        };

        if (request.StartTime.HasValue)
        {
            var startTimeNs = ((DateTimeOffset)request.StartTime.Value).ToUnixTimeMilliseconds() * 1_000_000;
            queryParams.Add($"start={startTimeNs}");
        }

        if (request.EndTime.HasValue)
        {
            var endTimeNs = ((DateTimeOffset)request.EndTime.Value).ToUnixTimeMilliseconds() * 1_000_000;
            queryParams.Add($"end={endTimeNs}");
        }

        var url = $"/loki/api/v1/query_range?{string.Join("&", queryParams)}";

        try
        {
            var response = await _httpClient.GetAsync(url);
            response.EnsureSuccessStatusCode();

            var jsonResponse = await response.Content.ReadAsStringAsync();
            var lokiResponse = JsonSerializer.Deserialize<LokiQueryResponse>(
                jsonResponse,
                new JsonSerializerOptions { PropertyNameCaseInsensitive = true }
            );

            if (lokiResponse?.Data?.Result != null)
            {
                foreach (var result in lokiResponse.Data.Result)
                {
                    foreach (var value in result.Values)
                    {
                        if (value.Count >= 2)
                        {
                            // Loki возвращает timestamp в наносекундах
                            if (long.TryParse(value[0], out var timestampNs))
                            {
                                var timestamp = DateTimeOffset.FromUnixTimeMilliseconds(timestampNs / 1000000).DateTime;
                                logs.Add(new LogEntry
                                {
                                    Timestamp = timestamp,
                                    Message = value[1]
                                });
                            }
                        }
                    }
                }
            }
        }
        catch (Exception ex)
        {
            throw new InvalidOperationException($"Ошибка при получении логов из Loki: {ex.Message}", ex);
        }

        return logs.OrderBy(l => l.Timestamp).ToList();
    }

    private static string BuildLogQLQuery(LogQueryRequest request)
    {
        var query = "{";
        var conditions = new List<string>();
        
        // Добавляем все лейблы
        foreach (var label in request.Labels)
        {
            if (!string.IsNullOrEmpty(label.Value))
            {
                conditions.Add($"{label.Key}=\"{label.Value}\"");
            }
            else
            {
                conditions.Add($"{label.Key}!=\"\"");
            }
        }
        
        query += string.Join(",", conditions);
        query += "}";
        
        return query;
    }
}