using Creative.Configuration;
using Creative.Models;
using HtmlAgilityPack;
using Microsoft.Extensions.Options;

namespace Creative.Services;

/// <summary>
/// Scrapes a URL and extracts structured business data.
/// Supports emulated mode for development without network calls.
/// </summary>
public class ScraperService
{
    private readonly CreativeConfig _config;
    private readonly IHttpClientFactory _httpFactory;
    private readonly ILogger<ScraperService> _logger;

    public ScraperService(
        IOptions<CreativeConfig> config,
        IHttpClientFactory httpFactory,
        ILogger<ScraperService> logger)
    {
        _config = config.Value;
        _httpFactory = httpFactory;
        _logger = logger;
    }

    /// <summary>
    /// Analyze a URL - scrape and extract structured content.
    /// </summary>
    public async Task<UrlAnalysis> AnalyzeUrlAsync(string url, CancellationToken ct)
    {
        if (!_config.EnableRealApi)
            return EmulateAnalysis(url);

        return await ScrapeRealAsync(url, ct);
    }

    #region Real Implementation

    private async Task<UrlAnalysis> ScrapeRealAsync(string url, CancellationToken ct)
    {
        _logger.LogInformation("[Scraper] Fetching {Url}", url);

        var client = _httpFactory.CreateClient();
        client.Timeout = TimeSpan.FromSeconds(_config.ScrapeTimeoutSeconds);
        client.DefaultRequestHeaders.UserAgent.ParseAdd(
            "Mozilla/5.0 (compatible; AdPlatformBot/1.0)");

        var html = await client.GetStringAsync(url, ct);

        var doc = new HtmlDocument();
        doc.LoadHtml(html);

        // Extract title
        var title = doc.DocumentNode
            .SelectSingleNode("//title")?.InnerText?.Trim();

        // Extract meta description
        var metaDesc = doc.DocumentNode
            .SelectSingleNode("//meta[@name='description']")?
            .GetAttributeValue("content", null)?.Trim();

        // Extract H1-H3 headings
        var headings = new List<string>();
        foreach (var tag in new[] { "h1", "h2", "h3" })
        {
            var nodes = doc.DocumentNode.SelectNodes($"//{tag}");
            if (nodes != null)
            {
                foreach (var node in nodes.Take(5))
                {
                    var text = HtmlEntity.DeEntitize(node.InnerText).Trim();
                    if (!string.IsNullOrWhiteSpace(text))
                        headings.Add(text);
                }
            }
        }

        // Extract body text snippet (first meaningful paragraphs)
        var bodySnippet = ExtractBodySnippet(doc);

        _logger.LogInformation("[Scraper] Extracted: title={Title} headings={Count}",
            title?.Length > 40 ? title[..40] + "..." : title, headings.Count);

        return new UrlAnalysis
        {
            Url = url,
            Title = title,
            MetaDescription = metaDesc,
            Headings = headings,
            BodySnippet = bodySnippet,
            InferredCategory = null,   // Category inference handled by CopyGenerator
            ScrapedAt = DateTimeOffset.UtcNow
        };
    }

    private static string? ExtractBodySnippet(HtmlDocument doc)
    {
        // Remove script/style nodes
        var removeNodes = doc.DocumentNode.SelectNodes("//script|//style|//nav|//footer|//header");
        if (removeNodes != null)
        {
            foreach (var node in removeNodes)
                node.Remove();
        }

        var paragraphs = doc.DocumentNode.SelectNodes("//p");
        if (paragraphs == null) return null;

        var texts = paragraphs
            .Select(p => HtmlEntity.DeEntitize(p.InnerText).Trim())
            .Where(t => t.Length > 30)
            .Take(3);

        var snippet = string.Join(" ", texts);
        return snippet.Length > 500 ? snippet[..500] : snippet;
    }

    #endregion

    #region Emulated

    private UrlAnalysis EmulateAnalysis(string url)
    {
        _logger.LogInformation("[Scraper] Emulated analysis for {Url}", url);

        // Parse domain for realistic emulated data
        var domain = "example.com";
        try
        {
            var uri = new Uri(url.StartsWith("http") ? url : $"https://{url}");
            domain = uri.Host.Replace("www.", "");
        }
        catch { /* use default */ }

        var businessName = domain.Split('.')[0];
        var titleCase = char.ToUpper(businessName[0]) + businessName[1..];

        return new UrlAnalysis
        {
            Url = url,
            Title = $"{titleCase} - Quality Products & Services",
            MetaDescription = $"{titleCase} offers premium products and services. Visit us today for the best experience.",
            Headings = new List<string>
            {
                $"Welcome to {titleCase}",
                "Our Services",
                "Why Choose Us",
                "Contact Us Today"
            },
            BodySnippet = $"{titleCase} has been serving customers with dedication and quality. " +
                          "We offer a wide range of products and services designed to meet your needs. " +
                          "Our team is committed to providing exceptional value and customer satisfaction.",
            InferredCategory = "Business Services",
            ScrapedAt = DateTimeOffset.UtcNow
        };
    }

    #endregion
}