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

namespace Gott.Services
{
    public class GoogleCheckResult
    {
        public string Status { get; set; }     // "ok", "invalid", "disabled", "error"
        public string Message { get; set; }
        public string[] Models { get; set; }
    }

    public class GoogleQuotaResult
    {
        public bool HasQuota { get; set; }
        public string Error { get; set; }
    }

    public static class GoogleKeyChecker
    {
        private static async Task<GoogleQuotaResult> CheckQuotaAsync(HttpClient client, string apiKey, string[] models)
        {
            try
            {
                // Günstigstes Modell wählen (flash > pro > erstbestes)
                var testModel = models.FirstOrDefault(m => m.Contains("flash", StringComparison.OrdinalIgnoreCase))
                             ?? models.FirstOrDefault(m => m.Contains("pro", StringComparison.OrdinalIgnoreCase))
                             ?? models.FirstOrDefault();

                if (testModel == null)
                    return new GoogleQuotaResult { HasQuota = false, Error = "Keine Modelle verfügbar" };

                var url = "https://generativelanguage.googleapis.com/v1/models/" + testModel
                        + ":generateContent?key=" + apiKey;

                var payload = new
                {
                    contents = new[] { new { parts = new[] { new { text = "hi" } } } },
                    generationConfig = new { maxOutputTokens = 1 }
                };

                var json = JsonSerializer.Serialize(payload);
                var content = new StringContent(json, System.Text.Encoding.UTF8, "application/json");
                var resp = await client.PostAsync(url, content);
                var statusCode = (int)resp.StatusCode;

                if (statusCode == 200)
                    return new GoogleQuotaResult { HasQuota = true };

                var body = await resp.Content.ReadAsStringAsync();

                // 429: Quota oder Rate-Limit
                if (statusCode == 429)
                {
                    if (body.Contains("RESOURCE_EXHAUSTED", StringComparison.OrdinalIgnoreCase)
                        && (body.Contains("quota", StringComparison.OrdinalIgnoreCase)
                            || body.Contains("limit_value", StringComparison.OrdinalIgnoreCase)))
                    {
                        // Quota auf 0 oder erschöpft
                        if (body.Contains("\"0\"") || body.Contains("GenerateContent"))
                            return new GoogleQuotaResult { HasQuota = false, Error = "Quota erschöpft (0 RPM)" };

                        return new GoogleQuotaResult { HasQuota = false, Error = "Quota erschöpft" };
                    }

                    // Echtes Rate-Limit → Key hat Quota, ist nur temporär blockiert
                    return new GoogleQuotaResult { HasQuota = true };
                }

                // 403: API nicht aktiviert oder Billing-Problem
                if (statusCode == 403)
                {
                    if (body.Contains("PERMISSION_DENIED", StringComparison.OrdinalIgnoreCase))
                        return new GoogleQuotaResult { HasQuota = false, Error = "Keine Berechtigung für generateContent" };

                    if (body.Contains("billing", StringComparison.OrdinalIgnoreCase))
                        return new GoogleQuotaResult { HasQuota = false, Error = "Billing nicht aktiviert" };

                    return new GoogleQuotaResult { HasQuota = false, Error = "Zugriff verweigert (403)" };
                }

                // Andere Fehler → konservativ als "kein Quota" behandeln
                return new GoogleQuotaResult { HasQuota = false, Error = "API-Fehler (" + statusCode + ")" };
            }
            catch (Exception)
            {
                // Bei Netzwerkfehler etc. → konservativ
                return new GoogleQuotaResult { HasQuota = false, Error = "Quota-Check fehlgeschlagen" };
            }
        }

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

                // Gemini / Generative Language API – listet verfügbare Modelle
                var url = "https://generativelanguage.googleapis.com/v1/models?key=" + apiKey;
                var resp = await client.GetAsync(url);
                var statusCode = (int)resp.StatusCode;

                if (statusCode == 400)
                    return new GoogleCheckResult { Status = "invalid", Message = "API-Key ungültig (400)" };

                if (statusCode == 403)
                {
                    // Key gültig, aber Gemini API nicht aktiviert (z.B. Maps-Key)
                    var errorBody = await resp.Content.ReadAsStringAsync();
                    if (errorBody.Contains("API_KEY_INVALID", StringComparison.OrdinalIgnoreCase))
                        return new GoogleCheckResult { Status = "invalid", Message = "API-Key ungültig (403)" };

                    return new GoogleCheckResult { Status = "disabled", Message = "Key gültig, aber Gemini API nicht aktiviert (403)" };
                }

                if (statusCode == 429)
                    return new GoogleCheckResult { Status = "rate_limited", Message = "Rate Limited (429)" };

                if (statusCode >= 400)
                    return new GoogleCheckResult { Status = "error", Message = "API-Fehler (" + statusCode + ")" };

                // 200 OK → Key gültig + Gemini API aktiv
                var body = await resp.Content.ReadAsStringAsync();
                var doc = JsonDocument.Parse(body);

                string[] models = Array.Empty<string>();
                if (doc.RootElement.TryGetProperty("models", out var modelsArr))
                {
                    var interestingPrefixes = new[] { "gemini" };
                    models = modelsArr.EnumerateArray()
                        .Where(m => m.TryGetProperty("name", out _))
                        .Select(m => m.GetProperty("name").GetString())
                        .Where(n => n != null)
                        .Select(n => n.StartsWith("models/", StringComparison.Ordinal) ? n.Substring(7) : n)
                        .Where(n => interestingPrefixes.Any(p => n.StartsWith(p, StringComparison.OrdinalIgnoreCase)))
                        .Distinct()
                        .OrderBy(x => x)
                        .ToArray();
                }

                // Plan-Erkennung
                string plan;
                if (models.Any(m => m.Contains("2.5", StringComparison.OrdinalIgnoreCase)
                                 || m.Contains("ultra", StringComparison.OrdinalIgnoreCase)))
                    plan = "Premium";
                else if (models.Any(m => m.Contains("pro", StringComparison.OrdinalIgnoreCase)))
                    plan = "Standard";
                else if (models.Any(m => m.Contains("flash", StringComparison.OrdinalIgnoreCase)))
                    plan = "Basic";
                else
                    plan = "Free";

                // Schritt 2: Echten generateContent-Call machen um Quota zu prüfen
                var quota = await CheckQuotaAsync(client, apiKey, models);

                var info = models.Length + " Gemini-Modelle · " + plan;
                if (!quota.HasQuota)
                {
                    info += " · " + quota.Error;
                    return new GoogleCheckResult
                    {
                        Status = "quota_exceeded",
                        Message = info,
                        Models = models
                    };
                }

                return new GoogleCheckResult
                {
                    Status = "ok",
                    Message = info,
                    Models = models
                };
            }
            catch (Exception ex)
            {
                return new GoogleCheckResult { Status = "error", Message = ex.Message };
            }
        }
    }
}