using System;
using System.Globalization;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

namespace Gott.Services
{
    public class KeyCheckResult
    {
        public string Status { get; set; }    // "ok", "invalid", "rate_limited", "quota_exceeded", "error"
        public string Message { get; set; }
        public string Plan { get; set; }       // "Max", "Pro", "Pro/Max", "API Console", "Unknown"
        public bool IsSubscription { get; set; }
        public double? Usage7d { get; set; }
        public double? Usage5h { get; set; }
        public double? Overage { get; set; }
        public string Status7d { get; set; }
        public string Status5h { get; set; }
        public string StatusOverage { get; set; }
    }

    public static class AnthropicKeyChecker
    {
        private const string CheckModel = "claude-sonnet-4-20250514";

        public static async Task<KeyCheckResult> CheckKeyAsync(IHttpClientFactory httpFactory, string apiKey)
        {
            try
            {
                var client = httpFactory.CreateClient();
                client.Timeout = TimeSpan.FromSeconds(30);

                var payload = JsonSerializer.Serialize(new
                {
                    model = CheckModel,
                    max_tokens = 1,
                    messages = new[] { new { role = "user", content = "hi" } }
                });

                var request = new HttpRequestMessage(HttpMethod.Post, "https://api.anthropic.com/v1/messages");
                request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);
                request.Headers.Add("anthropic-version", "2023-06-01");
                request.Headers.Add("anthropic-beta", "claude-code-20250219,oauth-2025-04-20");
                request.Headers.Add("User-Agent", "claude-cli/2.1.2 (external, cli)");
                request.Headers.Add("x-app", "cli");
                request.Headers.Add("anthropic-dangerous-direct-browser-access", "true");
                request.Content = new StringContent(payload, Encoding.UTF8, "application/json");

                var resp = await client.SendAsync(request);
                var statusCode = (int)resp.StatusCode;
                var headers = resp.Headers;

                if (statusCode == 401)
                {
                    var has7d = GetHeader(headers, "anthropic-ratelimit-unified-7d-utilization", "unified-7d-utilization");
                    var has5h = GetHeader(headers, "anthropic-ratelimit-unified-5h-utilization", "unified-5h-utilization");
                    if (has7d == null && has5h == null)
                        return new KeyCheckResult { Status = "invalid", Message = "Ungültig oder abgelaufen (401)", Plan = "Unknown" };
                }
                else if (statusCode == 429)
                {
                    return new KeyCheckResult { Status = "rate_limited", Message = "Rate Limited (429)", Plan = "Unknown" };
                }
                else if (statusCode == 403)
                {
                    return new KeyCheckResult { Status = "quota_exceeded", Message = "Insufficient Quota (403)", Plan = "Unknown" };
                }
                else if (statusCode >= 400)
                {
                    return new KeyCheckResult { Status = "error", Message = $"API-Fehler ({statusCode})", Plan = "Unknown" };
                }

                // Header auslesen
                var d7Util = GetHeader(headers, "anthropic-ratelimit-unified-7d-utilization", "unified-7d-utilization");
                var d5hUtil = GetHeader(headers, "anthropic-ratelimit-unified-5h-utilization", "unified-5h-utilization");
                var overageUtil = GetHeader(headers, "anthropic-ratelimit-unified-overage-utilization", "unified-overage-utilization");
                var d7Status = GetHeader(headers, "anthropic-ratelimit-unified-7d-status", "unified-7d-status");
                var d5hStatus = GetHeader(headers, "anthropic-ratelimit-unified-5h-status", "unified-5h-status");
                var overageStatus = GetHeader(headers, "anthropic-ratelimit-unified-overage-status", "unified-overage-status");
                var fallbackPct = GetHeader(headers, "anthropic-ratelimit-unified-fallback-percentage", "unified-fallback-percentage");

                var isSubscription = d7Util != null || d5hUtil != null;

                // Plan-Erkennung
                string plan;
                if (!isSubscription)
                    plan = "API Console";
                else if (overageUtil != null && double.TryParse(overageUtil, NumberStyles.Float, CultureInfo.InvariantCulture, out var ov) && ov > 0)
                    plan = "Max";
                else if (fallbackPct == null)
                    plan = "Pro";
                else
                    plan = "Pro/Max";

                var result = new KeyCheckResult
                {
                    Status = statusCode == 401 ? "usage_limited" : "ok",
                    Message = statusCode == 401 ? "Gültig, aber Usage-Limit erreicht (401)" : null,
                    Plan = plan,
                    IsSubscription = isSubscription,
                    Status7d = d7Status,
                    Status5h = d5hStatus,
                    StatusOverage = overageStatus
                };

                if (d7Util != null && double.TryParse(d7Util, NumberStyles.Float, CultureInfo.InvariantCulture, out var d7))
                    result.Usage7d = Math.Round(d7 * 100, 1);
                if (d5hUtil != null && double.TryParse(d5hUtil, NumberStyles.Float, CultureInfo.InvariantCulture, out var d5))
                    result.Usage5h = Math.Round(d5 * 100, 1);
                if (overageUtil != null && double.TryParse(overageUtil, NumberStyles.Float, CultureInfo.InvariantCulture, out var ovVal))
                    result.Overage = Math.Round(ovVal * 100, 1);

                return result;
            }
            catch (Exception ex)
            {
                return new KeyCheckResult { Status = "error", Message = ex.Message, Plan = "Unknown" };
            }
        }

        /// <summary>
        /// Extrahiert Plan/Usage-Metadaten nur aus Response-Headern (kein eigener HTTP-Request).
        /// Kann null zurückgeben wenn keine Usage-Header vorhanden sind.
        /// </summary>
        public static KeyCheckResult ExtractMetaFromHeaders(HttpResponseHeaders headers)
        {
            var d7Util = GetHeader(headers, "anthropic-ratelimit-unified-7d-utilization", "unified-7d-utilization");
            var d5hUtil = GetHeader(headers, "anthropic-ratelimit-unified-5h-utilization", "unified-5h-utilization");

            if (d7Util == null && d5hUtil == null)
                return null; // Keine Usage-Header → nichts zu updaten

            var overageUtil = GetHeader(headers, "anthropic-ratelimit-unified-overage-utilization", "unified-overage-utilization");
            var fallbackPct = GetHeader(headers, "anthropic-ratelimit-unified-fallback-percentage", "unified-fallback-percentage");

            string plan;
            if (overageUtil != null && double.TryParse(overageUtil, NumberStyles.Float, CultureInfo.InvariantCulture, out var ov) && ov > 0)
                plan = "Max";
            else if (fallbackPct == null)
                plan = "Pro";
            else
                plan = "Pro/Max";

            var result = new KeyCheckResult
            {
                Status = "valid",
                Plan = plan,
                IsSubscription = true
            };

            if (d7Util != null && double.TryParse(d7Util, NumberStyles.Float, CultureInfo.InvariantCulture, out var d7))
                result.Usage7d = Math.Round(d7 * 100, 1);
            if (d5hUtil != null && double.TryParse(d5hUtil, NumberStyles.Float, CultureInfo.InvariantCulture, out var d5))
                result.Usage5h = Math.Round(d5 * 100, 1);
            if (overageUtil != null && double.TryParse(overageUtil, NumberStyles.Float, CultureInfo.InvariantCulture, out var ovVal))
                result.Overage = Math.Round(ovVal * 100, 1);

            return result;
        }

        private static string GetHeader(HttpResponseHeaders headers, params string[] names)
        {
            foreach (var name in names)
                if (headers.TryGetValues(name, out var values))
                    return values.FirstOrDefault();
            return null;
        }
    }
}