using StellaOps.Integrations.Contracts;
using StellaOps.Integrations.Core;
using System.Net.Http.Headers;
using System.Text.Json;

namespace StellaOps.Integrations.Plugin.GitHubApp;

/// <summary>
/// GitHub App connector plugin for SCM integration.
/// Supports GitHub.com and GitHub Enterprise Server.
/// </summary>
public sealed class GitHubAppConnectorPlugin : IIntegrationConnectorPlugin
{
    private readonly TimeProvider _timeProvider;

    public GitHubAppConnectorPlugin()
        : this(TimeProvider.System)
    {
    }

    public GitHubAppConnectorPlugin(TimeProvider? timeProvider = null)
    {
        _timeProvider = timeProvider ?? TimeProvider.System;
    }

    public string Name => "github-app";

    public IntegrationType Type => IntegrationType.Scm;

    public IntegrationProvider Provider => IntegrationProvider.GitHubApp;

    public bool IsAvailable(IServiceProvider services) => true;

    public async Task<TestConnectionResult> TestConnectionAsync(IntegrationConfig config, CancellationToken cancellationToken = default)
    {
        var startTime = _timeProvider.GetUtcNow();

        using var client = CreateHttpClient(config);

        try
        {
            // Call GitHub API to verify authentication
            var response = await client.GetAsync("/app", cancellationToken);
            var duration = _timeProvider.GetUtcNow() - startTime;

            if (response.IsSuccessStatusCode)
            {
                var content = await response.Content.ReadAsStringAsync(cancellationToken);
                var app = JsonSerializer.Deserialize<GitHubAppResponse>(content, JsonOptions);

                return new TestConnectionResult(
                    Success: true,
                    Message: $"Connected as GitHub App: {app?.Name}",
                    Details: new Dictionary<string, string>
                    {
                        ["endpoint"] = config.Endpoint,
                        ["appName"] = app?.Name ?? "unknown",
                        ["appId"] = app?.Id.ToString() ?? "unknown",
                        ["slug"] = app?.Slug ?? "unknown"
                    },
                    Duration: duration);
            }

            var errorContent = await response.Content.ReadAsStringAsync(cancellationToken);
            return new TestConnectionResult(
                Success: false,
                Message: $"GitHub returned {response.StatusCode}",
                Details: new Dictionary<string, string>
                {
                    ["endpoint"] = config.Endpoint,
                    ["statusCode"] = ((int)response.StatusCode).ToString(),
                    ["error"] = errorContent.Length > 200 ? errorContent[..200] : errorContent
                },
                Duration: duration);
        }
        catch (Exception ex)
        {
            var duration = _timeProvider.GetUtcNow() - startTime;
            return new TestConnectionResult(
                Success: false,
                Message: $"Connection failed: {ex.Message}",
                Details: new Dictionary<string, string>
                {
                    ["endpoint"] = config.Endpoint,
                    ["error"] = ex.GetType().Name
                },
                Duration: duration);
        }
    }

    public async Task<HealthCheckResult> CheckHealthAsync(IntegrationConfig config, CancellationToken cancellationToken = default)
    {
        var startTime = _timeProvider.GetUtcNow();

        using var client = CreateHttpClient(config);

        try
        {
            // Check GitHub API status
            var response = await client.GetAsync("/rate_limit", cancellationToken);
            var duration = _timeProvider.GetUtcNow() - startTime;

            if (response.IsSuccessStatusCode)
            {
                var content = await response.Content.ReadAsStringAsync(cancellationToken);
                var rateLimit = JsonSerializer.Deserialize<GitHubRateLimitResponse>(content, JsonOptions);

                var remaining = rateLimit?.Resources?.Core?.Remaining ?? 0;
                var limit = rateLimit?.Resources?.Core?.Limit ?? 1;
                var percentUsed = (int)((1 - (double)remaining / limit) * 100);

                var status = percentUsed switch
                {
                    < 80 => HealthStatus.Healthy,
                    < 95 => HealthStatus.Degraded,
                    _ => HealthStatus.Unhealthy
                };

                return new HealthCheckResult(
                    Status: status,
                    Message: $"Rate limit: {remaining}/{limit} remaining ({percentUsed}% used)",
                    Details: new Dictionary<string, string>
                    {
                        ["remaining"] = remaining.ToString(),
                        ["limit"] = limit.ToString(),
                        ["percentUsed"] = percentUsed.ToString()
                    },
                    CheckedAt: _timeProvider.GetUtcNow(),
                    Duration: duration);
            }

            return new HealthCheckResult(
                Status: HealthStatus.Unhealthy,
                Message: $"GitHub returned {response.StatusCode}",
                Details: new Dictionary<string, string> { ["statusCode"] = ((int)response.StatusCode).ToString() },
                CheckedAt: _timeProvider.GetUtcNow(),
                Duration: duration);
        }
        catch (Exception ex)
        {
            var duration = _timeProvider.GetUtcNow() - startTime;
            return new HealthCheckResult(
                Status: HealthStatus.Unhealthy,
                Message: $"Health check failed: {ex.Message}",
                Details: new Dictionary<string, string> { ["error"] = ex.GetType().Name },
                CheckedAt: _timeProvider.GetUtcNow(),
                Duration: duration);
        }
    }

    private static HttpClient CreateHttpClient(IntegrationConfig config)
    {
        var baseUrl = string.IsNullOrEmpty(config.Endpoint) || config.Endpoint == "https://github.com"
            ? "https://api.github.com"
            : config.Endpoint.TrimEnd('/') + "/api/v3";

        var client = new HttpClient
        {
            BaseAddress = new Uri(baseUrl),
            Timeout = TimeSpan.FromSeconds(30)
        };

        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/vnd.github+json"));
        client.DefaultRequestHeaders.Add("X-GitHub-Api-Version", "2022-11-28");
        client.DefaultRequestHeaders.UserAgent.Add(new ProductInfoHeaderValue("StellaOps", "1.0"));

        // Add JWT token if provided (GitHub App authentication)
        if (!string.IsNullOrEmpty(config.ResolvedSecret))
        {
            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", config.ResolvedSecret);
        }

        return client;
    }

    private static readonly JsonSerializerOptions JsonOptions = new()
    {
        PropertyNameCaseInsensitive = true
    };

    private sealed class GitHubAppResponse
    {
        public long Id { get; set; }
        public string? Name { get; set; }
        public string? Slug { get; set; }
    }

    private sealed class GitHubRateLimitResponse
    {
        public GitHubResources? Resources { get; set; }
    }

    private sealed class GitHubResources
    {
        public GitHubRateLimit? Core { get; set; }
    }

    private sealed class GitHubRateLimit
    {
        public int Limit { get; set; }
        public int Remaining { get; set; }
        public int Reset { get; set; }
    }
}