using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using StellaOps.Doctor.Models;
using StellaOps.Doctor.Plugins;

namespace StellaOps.Doctor.Plugins.AI.Checks;

/// <summary>
/// Validates OpenAI API connectivity.
/// </summary>
public sealed class OpenAiProviderCheck : IDoctorCheck
{
    private const string DefaultModel = "gpt-4o";
    private const string DefaultEndpoint = "https://api.openai.com";

    /// <inheritdoc />
    public string CheckId => "check.ai.provider.openai";

    /// <inheritdoc />
    public string Name => "OpenAI Provider";

    /// <inheritdoc />
    public string Description => "Validates OpenAI API connectivity and authentication";

    /// <inheritdoc />
    public DoctorSeverity DefaultSeverity => DoctorSeverity.Warn;

    /// <inheritdoc />
    public IReadOnlyList<string> Tags => ["ai", "llm", "openai", "gpt", "advisoryai"];

    /// <inheritdoc />
    public TimeSpan EstimatedDuration => TimeSpan.FromSeconds(10);

    /// <inheritdoc />
    public bool CanRun(DoctorPluginContext context)
    {
        var apiKey = context.Configuration.GetValue<string>("AdvisoryAI:LlmProviders:OpenAI:ApiKey")
            ?? Environment.GetEnvironmentVariable("OPENAI_API_KEY");

        return !string.IsNullOrWhiteSpace(apiKey);
    }

    /// <inheritdoc />
    public async Task<DoctorCheckResult> RunAsync(DoctorPluginContext context, CancellationToken ct)
    {
        var result = context.CreateResult(CheckId, "stellaops.doctor.ai", DoctorCategory.AI.ToString());

        var apiKey = context.Configuration.GetValue<string>("AdvisoryAI:LlmProviders:OpenAI:ApiKey")
            ?? Environment.GetEnvironmentVariable("OPENAI_API_KEY");

        var endpoint = context.Configuration.GetValue<string>("AdvisoryAI:LlmProviders:OpenAI:Endpoint")
            ?? DefaultEndpoint;

        var model = context.Configuration.GetValue<string>("AdvisoryAI:LlmProviders:OpenAI:Model")
            ?? DefaultModel;

        if (string.IsNullOrWhiteSpace(apiKey))
        {
            return result
                .Skip("OpenAI API key not configured")
                .WithEvidence("OpenAI provider", e =>
                {
                    e.Add("Endpoint", endpoint);
                    e.Add("ApiKeyConfigured", "false");
                })
                .Build();
        }

        var httpClientFactory = context.Services.GetService<IHttpClientFactory>();
        if (httpClientFactory == null)
        {
            return result
                .Skip("HttpClientFactory not available")
                .WithEvidence("OpenAI provider", e =>
                {
                    e.Add("Endpoint", endpoint);
                    e.Add("Error", "IHttpClientFactory not registered");
                })
                .Build();
        }

        try
        {
            using var client = httpClientFactory.CreateClient();
            client.Timeout = TimeSpan.FromSeconds(10);
            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);

            // List models to validate API key (lightweight call)
            using var response = await client.GetAsync($"{endpoint}/v1/models", ct);

            if (response.IsSuccessStatusCode)
            {
                return result
                    .Pass("OpenAI API is accessible")
                    .WithEvidence("OpenAI provider", e =>
                    {
                        e.Add("Endpoint", endpoint);
                        e.Add("Model", model);
                        e.Add("ApiKeyConfigured", "true (masked)");
                        e.Add("StatusCode", ((int)response.StatusCode).ToString());
                    })
                    .Build();
            }

            var errorBody = await response.Content.ReadAsStringAsync(ct);
            var statusCode = (int)response.StatusCode;

            var issues = new List<string>();
            if (statusCode == 401)
            {
                issues.Add("Invalid API key");
            }
            else if (statusCode == 403)
            {
                issues.Add("Access forbidden - check API key permissions");
            }
            else if (statusCode == 429)
            {
                issues.Add("Rate limited - too many requests");
            }
            else
            {
                issues.Add($"API returned status {statusCode}");
            }

            return result
                .Warn($"OpenAI API issue: {response.StatusCode}")
                .WithEvidence("OpenAI provider", e =>
                {
                    e.Add("Endpoint", endpoint);
                    e.Add("Model", model);
                    e.Add("StatusCode", statusCode.ToString());
                    e.Add("Error", TruncateError(errorBody));
                })
                .WithCauses(issues.ToArray())
                .WithRemediation(r => r
                    .AddManualStep(1, "Verify API key", "Check OPENAI_API_KEY is valid")
                    .AddManualStep(2, "Check quotas", "Verify API usage limits on platform.openai.com"))
                .WithVerification("stella doctor --check check.ai.provider.openai")
                .Build();
        }
        catch (HttpRequestException ex)
        {
            return result
                .Fail($"Cannot connect to OpenAI API: {ex.Message}")
                .WithEvidence("OpenAI provider", e =>
                {
                    e.Add("Endpoint", endpoint);
                    e.Add("Error", ex.Message);
                })
                .WithCauses("Network connectivity issue or invalid endpoint")
                .WithRemediation(r => r
                    .AddManualStep(1, "Check network", "Verify network connectivity to api.openai.com")
                    .AddManualStep(2, "Check proxy", "Ensure proxy settings are configured if required"))
                .WithVerification("stella doctor --check check.ai.provider.openai")
                .Build();
        }
        catch (Exception ex) when (ex is not OperationCanceledException)
        {
            return result
                .Fail($"OpenAI API error: {ex.Message}")
                .WithEvidence("OpenAI provider", e =>
                {
                    e.Add("Endpoint", endpoint);
                    e.Add("Error", ex.GetType().Name);
                })
                .Build();
        }
    }

    private static string TruncateError(string error, int maxLength = 200)
    {
        if (string.IsNullOrWhiteSpace(error))
        {
            return "(empty)";
        }

        if (error.Length <= maxLength)
        {
            return error;
        }

        return error[..maxLength] + "...";
    }
}