using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Net.Http.Json;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;
using Predictalytics.Application.Interfaces;

namespace Predictalytics.Infrastructure.Providers.OpenRouter;

public class OpenRouterApiClient : IOpenRouterApiClient
{
    private readonly HttpClient _httpClient;
    private readonly IConfiguration _config;
    private readonly ILogger<OpenRouterApiClient> _logger;

    /// <summary>
    /// Ohne Schluessel wird gar nicht erst gesendet. Sonst quittiert OpenRouter jeden
    /// Aufruf mit 401, das landet als Error im Fehler-Stream des Deployment Centers und
    /// der Aufrufer versucht anschliessend, die Fehlermeldung als JSON zu lesen.
    /// </summary>
    private readonly bool _configured;

    public OpenRouterApiClient(HttpClient httpClient, IConfiguration config, ILogger<OpenRouterApiClient> logger)
    {
        _httpClient = httpClient;
        _config = config;
        _logger = logger;

        var baseUrl = _config["OpenRouter:BaseUrl"] ?? "https://openrouter.ai/api/v1";
        var apiKey = _config["OpenRouter:ApiKey"];
        
        _httpClient.BaseAddress = new Uri(baseUrl.EndsWith("/") ? baseUrl : baseUrl + "/");
        _configured = !string.IsNullOrWhiteSpace(apiKey);
        if (_configured)
        {
            _httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);
        }
        else
        {
            // Warning, nicht Error: eine fehlende KI-Anbindung ist ein Konfigurationszustand,
            // kein Stoerfall - die uebrige Analyse laeuft vollstaendig ohne sie.
            _logger.LogWarning("OpenRouter ist nicht konfiguriert (OpenRouter:ApiKey leer) - die KI-Strategieanalyse bleibt aus. Schluessel ueber die Umgebungsvariable OpenRouter__ApiKey setzen.");
        }
        // OpenRouter recommends adding a referer and title for ranking
        _httpClient.DefaultRequestHeaders.Add("HTTP-Referer", "http://localhost");
        _httpClient.DefaultRequestHeaders.Add("X-Title", "Predictalytics");
    }

    public async Task<string> GenerateChatCompletionAsync(string prompt, bool useManualModel = false, CancellationToken ct = default)
    {
        if (!_configured) return IOpenRouterApiClient.NotConfigured;

        var model = useManualModel 
            ? _config["OpenRouter:ManualAnalysisModel"] ?? "anthropic/claude-3-opus"
            : _config["OpenRouter:DefaultModel"] ?? "google/gemini-flash-1.5";

        var requestBody = new
        {
            model = model,
            messages = new[]
            {
                new { role = "system", content = "You are an expert crypto and prediction market analyst. You analyze a trader's history and deduce their strategy, strengths, and weaknesses." },
                new { role = "user", content = prompt }
            }
        };

        try
        {
            var response = await _httpClient.PostAsJsonAsync("chat/completions", requestBody, ct);
            response.EnsureSuccessStatusCode();

            var result = await response.Content.ReadFromJsonAsync<OpenRouterResponse>(cancellationToken: ct);
            return result?.Choices?[0]?.Message?.Content ?? "No response generated.";
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to generate chat completion from OpenRouter using model {Model}", model);
            return $"Error: {ex.Message}";
        }
    }

    private class OpenRouterResponse
    {
        [JsonPropertyName("choices")]
        public Choice[]? Choices { get; set; }
    }

    private class Choice
    {
        [JsonPropertyName("message")]
        public Message? Message { get; set; }
    }

    private class Message
    {
        [JsonPropertyName("content")]
        public string? Content { get; set; }
    }
}