using System;
using System.Collections.Generic;
using System.Globalization;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using FinlyticFundamentals.Entities;
using Microsoft.Extensions.Logging;
using Microsoft.Playwright;

namespace FinlyticFundamentals.Services;

public interface IHtmlFallbackScraper
{
    Task<ScrapedFundamentalsData?> ScrapeFallbackAsync(string isin, string ticker, CancellationToken cancellationToken = default);
}

/// <summary>
/// Fallback scraper using Playwright (headless Chromium) to scrape Yahoo Finance pages
/// for alternative ticker symbols (e.g., APC.SG) whose data is not available via the API.
/// Targets stable data-testid selectors from the rendered Yahoo Finance SPA.
/// </summary>
public class HtmlFallbackScraper : IHtmlFallbackScraper, IAsyncDisposable
{
    private readonly ILogger<HtmlFallbackScraper> _logger;

    private IPlaywright? _playwright;
    private IBrowser?    _browser;
    private readonly SemaphoreSlim _browserLock = new(1, 1);

    public HtmlFallbackScraper(ILogger<HtmlFallbackScraper> logger)
    {
        _logger = logger;
    }

    public async Task<ScrapedFundamentalsData?> ScrapeFallbackAsync(
        string isin,
        string ticker,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation(
            "[YahooFallbackScraper] Executing Playwright Fallback Scrape for ticker '{Ticker}' (ISIN: {Isin})...",
            ticker, isin);

        try
        {
            var browser = await GetOrInitBrowserAsync(cancellationToken);

            var fundamentals = new AssetFundamentalsEntity
            {
                Isin                = isin,
                PrimaryTicker       = ticker,
                LastUpdatedAt       = DateTime.UtcNow,
                LastStaticUpdatedAt = DateTime.UtcNow
            };

            var tickerData = new TickerFundamentalsEntity
            {
                Ticker        = ticker,
                Isin          = isin,
                LastUpdatedAt = DateTime.UtcNow
            };

            fundamentals.CompanyName = ticker;
            // Share context for both pages so we only have to accept cookies once
            await using (var ctx = await browser.NewContextAsync(BuildContextOptions()))
            {
                // ── 1. Key Statistics Page ─────────────────────────────────────
                var statsUrl = $"https://finance.yahoo.com/quote/{Uri.EscapeDataString(ticker)}/key-statistics/";
                _logger.LogInformation("[YahooFallbackScraper] Navigating to stats page: {Url}", statsUrl);

                var statsPage = await ctx.NewPageAsync();
                try
                {
                    await statsPage.GotoAsync(statsUrl, new PageGotoOptions
                    {
                        WaitUntil = WaitUntilState.DOMContentLoaded,
                        Timeout   = 45_000
                    });
                    
                    await HandleConsentAsync(statsPage);

                    // Wait for the statistics section to be visible
                    await statsPage.WaitForSelectorAsync(
                        "section[data-testid='qsp-statistics'], section[data-testid='stats-highlight']",
                        new PageWaitForSelectorOptions { Timeout = 20_000 });

                    // --- Valuation Measures Table ---
                    var valuationRows = await statsPage.QuerySelectorAllAsync(
                        "section[data-testid='qsp-statistics'] table tbody tr");

                    foreach (var row in valuationRows)
                    {
                        var cells = await row.QuerySelectorAllAsync("td");
                        if (cells.Count < 2) continue;

                        var label = (await cells[0].InnerTextAsync()).Trim();
                        var value = (await cells[1].InnerTextAsync()).Trim();

                        if (string.IsNullOrWhiteSpace(value) || value == "N/A" || value == "--") continue;

                        switch (NormalizeLabel(label))
                        {
                            case "market cap":                    tickerData.MarketCapitalization = ParseSuffixNumber(value) ?? 0m; break;
                            case "enterprise value":              tickerData.EnterpriseValue      = ParseSuffixNumber(value) ?? 0m; break;
                            case "trailing p/e":                  tickerData.PeRatioTrailing      = ParseDecimal(value);            break;
                            case "forward p/e":                   tickerData.PeRatioForward       = ParseDecimal(value);            break;
                            case "peg ratio (5yr expected)":      tickerData.PegRatio             = ParseDecimal(value);            break;
                            case "price/sales":                   tickerData.PsRatio              = ParseDecimal(value);            break;
                            case "price/book":                    tickerData.PbRatio              = ParseDecimal(value);            break;
                            case "enterprise value/revenue":      tickerData.EvToRevenue          = ParseDecimal(value);            break;
                            case "enterprise value/ebitda":       tickerData.EvToEbitda           = ParseDecimal(value);            break;
                        }
                    }

                    // --- Financial Highlight Cards ---
                    var highlightRows = await statsPage.QuerySelectorAllAsync(
                        "div[data-testid='stats-highlight'] section[data-testid='card-container'] table tr");

                    foreach (var row in highlightRows)
                    {
                        var cells = await row.QuerySelectorAllAsync("td");
                        if (cells.Count < 2) continue;

                        var label = (await cells[0].InnerTextAsync()).Trim();
                        var value = (await cells[1].InnerTextAsync()).Trim();

                        if (string.IsNullOrWhiteSpace(value) || value == "N/A" || value == "--") continue;

                        switch (NormalizeLabel(label))
                        {
                            case "profit margin":           tickerData.NetProfitMargin  = ParsePercent(value); break;
                            case "operating margin":        tickerData.OperatingMargin  = ParsePercent(value); break;
                            case "return on assets":        tickerData.ReturnOnAssets   = ParsePercent(value); break;
                            case "return on equity":        tickerData.ReturnOnEquity   = ParsePercent(value); break;
                            case "current ratio":           tickerData.CurrentRatio     = ParseDecimal(value); break;
                            case "quick ratio":             tickerData.QuickRatio       = ParseDecimal(value); break;
                            case "total debt/equity":       tickerData.DebtToEquity     = ParseDecimal(value); break;
                            case "52 week high":            tickerData.FiftyTwoWeekHigh = ParseDecimal(value) ?? 0m; break;
                            case "52 week low":             tickerData.FiftyTwoWeekLow  = ParseDecimal(value) ?? 0m; break;
                            case "forward annual dividend yield":
                            case "trailing annual dividend yield":
                                tickerData.DividendYield ??= ParsePercent(value); break;
                            case "payout ratio":            tickerData.PayoutRatio      = ParsePercent(value); break;
                        }
                    }

                    _logger.LogInformation(
                        "[YahooFallbackScraper] Stats parsed for '{Ticker}': MarketCap={MarketCap}, EV={EV}, TrailingPE={PE}, ForwardPE={FPE}",
                        ticker, tickerData.MarketCapitalization, tickerData.EnterpriseValue,
                        tickerData.PeRatioTrailing, tickerData.PeRatioForward);
                }
                catch (TimeoutException tex)
                {
                    _logger.LogWarning(tex,
                        "[YahooFallbackScraper] Timeout waiting for stats page selectors for ticker '{Ticker}'. Page may not have loaded.", ticker);
                }
                finally
                {
                    await statsPage.CloseAsync();
                }

            }

            // ── 2. Guard: no meaningful data ──────────────────────────────
            if (tickerData.MarketCapitalization == 0)
            {
                _logger.LogWarning(
                    "[YahooFallbackScraper] Playwright scrape for '{Ticker}' produced no meaningful data (MarketCap=0). Returning NULL.",
                    ticker);
                return null;
            }

            _logger.LogInformation(
                "[YahooFallbackScraper] Playwright Fallback Scrape complete for '{Ticker}'. MarketCap={MarketCap}",
                ticker, tickerData.MarketCapitalization);

            return new ScrapedFundamentalsData(
                fundamentals,
                tickerData,
                new List<CompanyExecutiveEntity>(),
                new List<FinancialStatementEntity>(),
                new List<ForwardEstimateEntity>()
            );
        }
        catch (Exception ex)
        {
            _logger.LogError(ex,
                "[YahooFallbackScraper] Error during Playwright Fallback Scrape for ticker '{Ticker}' (ISIN: {Isin})",
                ticker, isin);
            return null;
        }
    }

    // ── Browser Lifecycle ──────────────────────────────────────────────────

    private async Task<IBrowser> GetOrInitBrowserAsync(CancellationToken cancellationToken = default)
    {
        if (_browser != null) return _browser;

        await _browserLock.WaitAsync(cancellationToken);
        try
        {
            if (_browser != null) return _browser;

            _playwright = await Playwright.CreateAsync();
            _browser    = await _playwright.Chromium.LaunchAsync(new BrowserTypeLaunchOptions
            {
                Headless = true,
                Args     = new[] { "--no-sandbox", "--disable-dev-shm-usage" }
            });

 
            _logger.LogInformation("[YahooFallbackScraper] Playwright Chromium browser initialized.");
            return _browser;
        }
        finally
        {
            _browserLock.Release();
        }
    }

    private static BrowserNewContextOptions BuildContextOptions() => new()
    {
        UserAgent    = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36",
        ViewportSize = new ViewportSize { Width = 1280, Height = 900 },
        Locale       = "en-US",
        ExtraHTTPHeaders = new Dictionary<string, string>
        {
            ["Accept-Language"] = "en-US,en;q=0.9"
        }
    };

    public async ValueTask DisposeAsync()
    {
        if (_browser != null) await _browser.CloseAsync();
        _playwright?.Dispose();
    }

    // ── Parse Helpers ─────────────────────────────────────────────────────

    private async Task HandleConsentAsync(IPage page)
    {
        try
        {
            if (page.Url.Contains("consent.yahoo.com"))
            {
                _logger.LogInformation("[YahooFallbackScraper] Redirected to consent page. Attempting to accept cookies...");
                var agreeBtn = page.Locator("button[name='agree'], button.accept-all, button[value='agree']");
                if (await agreeBtn.CountAsync() > 0)
                {
                    await agreeBtn.First.ClickAsync();
                    await page.WaitForNavigationAsync(new PageWaitForNavigationOptions { WaitUntil = WaitUntilState.DOMContentLoaded, Timeout = 20_000 });
                    _logger.LogInformation("[YahooFallbackScraper] Cookie consent accepted. Navigated back to: {Url}", page.Url);
                }
                else
                {
                    _logger.LogWarning("[YahooFallbackScraper] On consent page but could not find the 'agree' button.");
                }
            }
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "[YahooFallbackScraper] Error while handling cookie consent.");
        }
    }

    /// <summary>Lowercases, strips trailing digits, common Yahoo qualifiers like (ttm), (mrq), and extra spaces.</summary>
    private static string NormalizeLabel(string label)
    {
        label = label.ToLowerInvariant();
        label = Regex.Replace(label, @"\s*\d+\s*$", ""); // trailing superscripts
        label = label.Replace("(ttm)", "").Replace("(mrq)", "").Replace("(fye)", ""); // remove date qualifiers
        label = Regex.Replace(label, @"\s+", " "); // collapse spaces
        return label.Trim();
    }

    private static decimal? ParseDecimal(string? input)
    {
        if (string.IsNullOrWhiteSpace(input) || input == "N/A" || input == "--" || input == "-") return null;
        input = Regex.Replace(input, @"[^\d.-]", "");
        return decimal.TryParse(input, NumberStyles.Any, CultureInfo.InvariantCulture, out var val) ? val : null;
    }

    private static decimal? ParsePercent(string? input)
    {
        var val = ParseDecimal(input);
        if (!val.HasValue) return null;
        return val.Value > 1m ? val.Value / 100m : val.Value;
    }

    private static decimal? ParseSuffixNumber(string? input)
    {
        if (string.IsNullOrWhiteSpace(input) || input == "N/A" || input == "--" || input == "-") return null;
        input = input.Trim();
        decimal multiplier = input.EndsWith("T", StringComparison.OrdinalIgnoreCase) ? 1_000_000_000_000m
                           : input.EndsWith("B", StringComparison.OrdinalIgnoreCase) ? 1_000_000_000m
                           : input.EndsWith("M", StringComparison.OrdinalIgnoreCase) ? 1_000_000m
                           : input.EndsWith("K", StringComparison.OrdinalIgnoreCase) ? 1_000m
                           : 1m;
        var numPart = Regex.Replace(input, @"[^\d.-]", "");
        var val     = ParseDecimal(numPart);
        return val.HasValue ? val.Value * multiplier : null;
    }
}