using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using FinlyticCore.Dtos.Yahoo;
using FinlyticCore.Models.Settings;
using FinlyticCore.Services;

namespace FinlyticCore.Services.Yahoo;

public class YahooFinanceClient
{
    private readonly HttpClient _httpClient;
    private readonly CookieContainer _cookieContainer;
    private readonly IFinlyticLogger<YahooFinanceClient>? _finlyticLogger;
    private readonly ISettingsService? _settingsService;
    private readonly SemaphoreSlim _authLock = new(1, 1);

    private string? _crumb;
    private DateTime _lastAuthTime = DateTime.MinValue;

    /// <summary>
    /// Standard modules available for the quoteSummary endpoint.
    /// </summary>
    public static readonly string[] StandardQuoteSummaryModules = new[]
    {
        "assetProfile",
        "financialData",
        "defaultKeyStatistics",
        "summaryDetail",
        "incomeStatementHistory",
        "incomeStatementHistoryQuarterly",
        "balanceSheetHistory",
        "balanceSheetHistoryQuarterly",
        "cashflowStatementHistory",
        "cashflowStatementHistoryQuarterly",
        "calendarEvents"
    };

    public YahooFinanceClient(
        IFinlyticLogger<YahooFinanceClient>? finlyticLogger = null,
        ISettingsService? settingsService = null,
        HttpClient? httpClient = null)
    {
        _finlyticLogger = finlyticLogger;
        _settingsService = settingsService;
        _cookieContainer = new CookieContainer();

        if (httpClient != null)
        {
            _httpClient = httpClient;
        }
        else
        {
            var handler = new HttpClientHandler
            {
                CookieContainer = _cookieContainer,
                UseCookies = true,
                AllowAutoRedirect = true
            };

            _httpClient = new HttpClient(handler);
            _httpClient.DefaultRequestHeaders.Add("User-Agent",
                "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36");
        }
    }

    /// <summary>
    /// Ensures that an active Yahoo session (Cookie + dynamic Crumb token) is initialized.
    /// Uses persistent DB caching and only refreshes when the crumb is invalid or forceRefresh is true.
    /// </summary>
    public async Task<string?> EnsureAuthenticatedAsync(bool forceRefresh = false,
        CancellationToken cancellationToken = default)
    {
        await _authLock.WaitAsync(cancellationToken);
        try
        {
            // 1. Check in-memory crumb
            if (!forceRefresh && !string.IsNullOrWhiteSpace(_crumb))
            {
                return _crumb;
            }

            // 2. Check persistent DB cache via SettingsService
            if (!forceRefresh && _settingsService != null)
            {
                try
                {
                    var cachedCrumb = await _settingsService.GetSettingAsync(CoreSettingKeys.YahooAuthCrumb, cancellationToken);
                    var cachedCookies = await _settingsService.GetSettingAsync(CoreSettingKeys.YahooAuthCookie, cancellationToken);

                    if (!string.IsNullOrWhiteSpace(cachedCrumb) && !string.IsNullOrWhiteSpace(cachedCookies))
                    {
                        RestoreCookies(cachedCookies);
                        _crumb = cachedCrumb;
                        _lastAuthTime = DateTime.UtcNow;

                        if (_finlyticLogger != null)
                            await _finlyticLogger.LogInfoAsync(CoreSettingKeys.YahooClientChannel, "[YahooFinanceClient] Restored cached Yahoo session & crumb from database ({Crumb}).", _crumb);
                        return _crumb;
                    }
                }
                catch (Exception ex)
                {
                    if (_finlyticLogger != null)
                        await _finlyticLogger.LogWarningAsync(CoreSettingKeys.YahooClientChannel, ex, "[YahooFinanceClient] Error restoring cached Yahoo session from DB.");
                }
            }

            if (_finlyticLogger != null)
                await _finlyticLogger.LogInfoAsync(CoreSettingKeys.YahooClientChannel, "[YahooFinanceClient] Authenticating fresh session with Yahoo (Cookie + Crumb)...");

            // 3. Send GET request to fc.yahoo.com to obtain session cookie A3
            using (var initRequest = new HttpRequestMessage(HttpMethod.Get, "https://fc.yahoo.com"))
            {
                initRequest.Headers.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36");
                initRequest.Headers.Add("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8");
                using var initResponse = await _httpClient.SendAsync(initRequest, cancellationToken);
            }

            // 4. Send GET request to getcrumb to obtain dynamic crumb token
            string[] crumbUrls = new[]
            {
                "https://query1.finance.yahoo.com/v1/test/getcrumb",
                "https://query2.finance.yahoo.com/v1/test/getcrumb"
            };

            foreach (var url in crumbUrls)
            {
                try
                {
                    using var crumbRequest = new HttpRequestMessage(HttpMethod.Get, url);
                    crumbRequest.Headers.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36");
                    crumbRequest.Headers.Add("Accept", "*/*");

                    using var crumbResponse = await _httpClient.SendAsync(crumbRequest, cancellationToken);
                    if (crumbResponse.IsSuccessStatusCode)
                    {
                        var crumbText = await crumbResponse.Content.ReadAsStringAsync(cancellationToken);
                        if (!string.IsNullOrWhiteSpace(crumbText))
                        {
                            _crumb = crumbText.Trim('"', ' ', '\t', '\r', '\n');
                            _lastAuthTime = DateTime.UtcNow;

                            // Persist to DB cache via SettingsService
                            if (_settingsService != null)
                            {
                                try
                                {
                                    var serializedCookies = SerializeCookies();
                                    await _settingsService.SetSettingAsync(CoreSettingKeys.YahooAuthCrumb, _crumb, cancellationToken);
                                    if (!string.IsNullOrWhiteSpace(serializedCookies))
                                    {
                                        await _settingsService.SetSettingAsync(CoreSettingKeys.YahooAuthCookie, serializedCookies, cancellationToken);
                                    }
                                }
                                catch (Exception persistEx)
                                {
                                    if (_finlyticLogger != null)
                                        await _finlyticLogger.LogWarningAsync(CoreSettingKeys.YahooClientChannel, persistEx, "[YahooFinanceClient] Failed to persist new Yahoo session to database.");
                                }
                            }

                            if (_finlyticLogger != null)
                                await _finlyticLogger.LogInfoAsync(CoreSettingKeys.YahooClientChannel, "[YahooFinanceClient] Acquired fresh Crumb token successfully and persisted: {Crumb}", _crumb);
                            return _crumb;
                        }
                    }
                    else
                    {
                        if (_finlyticLogger != null)
                            await _finlyticLogger.LogWarningAsync(CoreSettingKeys.YahooClientChannel, "[YahooFinanceClient] Endpoint '{Url}' returned status {Status}", url, crumbResponse.StatusCode);
                    }
                }
                catch
                {
                    // Fallthrough to next endpoint
                }
            }

            if (_finlyticLogger != null)
                await _finlyticLogger.LogWarningAsync(CoreSettingKeys.YahooClientChannel, "[YahooFinanceClient] Failed to fetch crumb token from all endpoints.");
            return null;
        }
        catch (Exception ex)
        {
            if (_finlyticLogger != null)
                await _finlyticLogger.LogErrorAsync(CoreSettingKeys.YahooClientChannel, ex, "[YahooFinanceClient] Exception during Cookie & Crumb authentication.");
            return null;
        }
        finally
        {
            _authLock.Release();
        }
    }

    private string SerializeCookies()
    {
        try
        {
            var cookies = _cookieContainer.GetAllCookies();
            var pairs = new List<string>();
            foreach (Cookie cookie in cookies)
            {
                pairs.Add($"{cookie.Name}={cookie.Value}");
            }
            return string.Join(";", pairs);
        }
        catch
        {
            return string.Empty;
        }
    }

    private void RestoreCookies(string serializedCookies)
    {
        if (string.IsNullOrWhiteSpace(serializedCookies)) return;

        try
        {
            var parts = serializedCookies.Split(';', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
            foreach (var part in parts)
            {
                var eqIdx = part.IndexOf('=');
                if (eqIdx > 0 && eqIdx < part.Length - 1)
                {
                    var name = part.Substring(0, eqIdx).Trim();
                    var val = part.Substring(eqIdx + 1).Trim();
                    _cookieContainer.Add(new Cookie(name, val, "/", ".yahoo.com"));
                }
            }
        }
        catch
        {
            // Ignore cookie restore errors
        }
    }

    /// <summary>
    /// Searches for tickers, names, ISINs, or companies via the Yahoo Finance search API.
    /// URL: https://query2.finance.yahoo.com/v1/finance/search?q={query}&amp;quotesCount={quotesCount}&amp;newsCount={newsCount}
    /// Note: Does not require Cookie/Crumb authentication.
    /// </summary>
    public async Task<YahooSearchResponseDto?> SearchAsync(
        string query,
        int quotesCount = 10,
        int newsCount = 0,
        CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(query)) return null;

        try
        {
            var url =
                $"https://query2.finance.yahoo.com/v1/finance/search?q={Uri.EscapeDataString(query)}&quotesCount={quotesCount}&newsCount={newsCount}";
            using var response = await _httpClient.GetAsync(url, cancellationToken);

            if (!response.IsSuccessStatusCode)
            {
                if (_finlyticLogger != null)
                    await _finlyticLogger.LogWarningAsync(CoreSettingKeys.YahooClientChannel, "[YahooFinanceClient] Search for '{Query}' failed with status {Status}", query, response.StatusCode);
                return null;
            }

            var json = await response.Content.ReadAsStringAsync(cancellationToken);
            return JsonSerializer.Deserialize<YahooSearchResponseDto>(json, GetJsonOptions());
        }
        catch (Exception ex)
        {
            if (_finlyticLogger != null)
                await _finlyticLogger.LogErrorAsync(CoreSettingKeys.YahooClientChannel, ex, "[YahooFinanceClient] Exception during Search for query '{Query}'", query);
            return null;
        }
    }

    /// <summary>
    /// Retrieves fundamentals and company metadata using the quoteSummary endpoint.
    /// URL: https://query2.finance.yahoo.com/v10/finance/quoteSummary/{symbol}?crumb={crumb}&amp;modules={modules}
    /// </summary>
    public async Task<YahooQuoteSummaryResponseDto?> GetQuoteSummaryAsync(
        string symbol,
        IEnumerable<string> modules,
        CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(symbol)) return null;

        var moduleList = string.Join(",", modules);
        return await ExecuteWithRetryAsync(async (crumb) =>
        {
            var url =
                $"https://query2.finance.yahoo.com/v10/finance/quoteSummary/{Uri.EscapeDataString(symbol)}?crumb={Uri.EscapeDataString(crumb)}&modules={Uri.EscapeDataString(moduleList)}";
            using var response = await _httpClient.GetAsync(url, cancellationToken);

            if (!response.IsSuccessStatusCode)
            {
                if (_finlyticLogger != null)
                    await _finlyticLogger.LogWarningAsync(CoreSettingKeys.YahooClientChannel, "[YahooFinanceClient] GetQuoteSummary for '{Symbol}' failed with status {Status}", symbol, response.StatusCode);
                return (
                    response.StatusCode == HttpStatusCode.Unauthorized ||
                    response.StatusCode == HttpStatusCode.Forbidden, null);
            }

            var json = await response.Content.ReadAsStringAsync(cancellationToken);
            var dto = JsonSerializer.Deserialize<YahooQuoteSummaryResponseDto>(json, GetJsonOptions());
            return (false, dto);
        }, cancellationToken);
    }

    /// <summary>
    /// Convenience method to fetch all standard quoteSummary modules for a given symbol.
    /// </summary>
    public Task<YahooQuoteSummaryResponseDto?> GetFullQuoteSummaryAsync(string symbol,
        CancellationToken cancellationToken = default)
    {
        return GetQuoteSummaryAsync(symbol, StandardQuoteSummaryModules, cancellationToken);
    }

    /// <summary>
    /// Retrieves historical OHLCV chart data for a given symbol.
    /// URL: https://query1.finance.yahoo.com/v8/finance/chart/{symbol}?range={range}&amp;interval={interval}&amp;crumb={crumb}
    /// </summary>
    public async Task<YahooChartResponseDto?> GetChartAsync(
        string symbol,
        string range = "1y",
        string interval = "1d",
        CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(symbol)) return null;

        return await ExecuteWithRetryAsync(async (crumb) =>
        {
            var url =
                $"https://query1.finance.yahoo.com/v8/finance/chart/{Uri.EscapeDataString(symbol)}?range={Uri.EscapeDataString(range)}&interval={Uri.EscapeDataString(interval)}&crumb={Uri.EscapeDataString(crumb)}";
            using var response = await _httpClient.GetAsync(url, cancellationToken);

            if (!response.IsSuccessStatusCode)
            {
                if (_finlyticLogger != null)
                    await _finlyticLogger.LogWarningAsync(CoreSettingKeys.YahooClientChannel, "[YahooFinanceClient] GetChart for '{Symbol}' failed with status {Status}", symbol, response.StatusCode);
                return (
                    response.StatusCode == HttpStatusCode.Unauthorized ||
                    response.StatusCode == HttpStatusCode.Forbidden, null);
            }

            var json = await response.Content.ReadAsStringAsync(cancellationToken);
            var dto = JsonSerializer.Deserialize<YahooChartResponseDto>(json, GetJsonOptions());
            return (false, dto);
        }, cancellationToken);
    }

    /// <summary>
    /// Retrieves quick real-time price quotes for one or more symbols.
    /// URL: https://query1.finance.yahoo.com/v7/finance/quote?symbols={symbols}&amp;crumb={crumb}
    /// </summary>
    public async Task<YahooQuoteResponseDto?> GetQuotesAsync(
        IEnumerable<string> symbols,
        CancellationToken cancellationToken = default)
    {
        var symbolList = symbols.Where(s => !string.IsNullOrWhiteSpace(s)).ToList();
        if (symbolList.Count == 0) return null;

        var symbolsParam = string.Join(",", symbolList);
        return await ExecuteWithRetryAsync(async (crumb) =>
        {
            var url =
                $"https://query1.finance.yahoo.com/v7/finance/quote?symbols={Uri.EscapeDataString(symbolsParam)}&crumb={Uri.EscapeDataString(crumb)}";
            using var response = await _httpClient.GetAsync(url, cancellationToken);

            if (!response.IsSuccessStatusCode)
            {
                if (_finlyticLogger != null)
                    await _finlyticLogger.LogWarningAsync(CoreSettingKeys.YahooClientChannel, "[YahooFinanceClient] GetQuotes failed with status {Status}", response.StatusCode);
                return (
                    response.StatusCode == HttpStatusCode.Unauthorized ||
                    response.StatusCode == HttpStatusCode.Forbidden, null);
            }

            var json = await response.Content.ReadAsStringAsync(cancellationToken);
            var dto = JsonSerializer.Deserialize<YahooQuoteResponseDto>(json, GetJsonOptions());
            return (false, dto);
        }, cancellationToken);
    }

    /// <summary>
    /// Convenient helper method to fetch the current live price for a single symbol (e.g., "^VIX").
    /// </summary>
    public async Task<decimal?> GetLivePriceAsync(string symbol, CancellationToken cancellationToken = default)
    {
        if (string.IsNullOrWhiteSpace(symbol)) return null;

        var quotes = await GetQuotesAsync(new[] { symbol }, cancellationToken);
        var item = quotes?.QuoteResponse?.Result?.FirstOrDefault();

        if (item?.RegularMarketPrice.HasValue == true && item.RegularMarketPrice.Value > 0)
        {
            return Convert.ToDecimal(item.RegularMarketPrice.Value);
        }

        return null;
    }

    private async Task<T?> ExecuteWithRetryAsync<T>(
        Func<string, Task<(bool isAuthError, T? result)>> action,
        CancellationToken cancellationToken) where T : class
    {
        var crumb = await EnsureAuthenticatedAsync(false, cancellationToken);
        if (string.IsNullOrEmpty(crumb)) return null;

        var (isAuthError, result) = await action(crumb);
        if (!isAuthError && result != null)
        {
            return result;
        }

        if (isAuthError)
        {
            if (_finlyticLogger != null)
                await _finlyticLogger.LogInfoAsync(CoreSettingKeys.YahooClientChannel, "[YahooFinanceClient] Authentication error encountered (401/403). Re-authenticating...");
            crumb = await EnsureAuthenticatedAsync(true, cancellationToken);
            if (string.IsNullOrEmpty(crumb)) return null;

            var (_, retryResult) = await action(crumb);
            return retryResult;
        }

        return result;
    }

    private static JsonSerializerOptions GetJsonOptions()
    {
        return new JsonSerializerOptions
        {
            PropertyNameCaseInsensitive = true,
            PropertyNamingPolicy = JsonNamingPolicy.CamelCase
        };
    }
}