using System;
using System.Collections.Generic;
using CRAWLER.Models;
using HtmlAgilityPack;

namespace CRAWLER.Parsing;

internal sealed class CatalogPageParser
{
    public IReadOnlyList<CatalogListItem> Parse(string html, string baseUrl)
    {
        var document = new HtmlDocument();
        document.LoadHtml(html ?? string.Empty);

        var items = new List<CatalogListItem>();
        var nodes = document.DocumentNode.SelectNodes("//div[contains(concat(' ', normalize-space(@class), ' '), ' sivreestre ')]");
        if (nodes == null)
        {
            return items;
        }

        foreach (var node in nodes)
        {
            var item = new CatalogListItem
            {
                RegistryNumber = ReadBlockValue(node, "№ в госреестре"),
                Name = ReadBlockValue(node, "Наименование"),
                TypeDesignation = ReadBlockValue(node, "Тип"),
                Manufacturer = ReadBlockValue(node, "Производитель"),
                VerificationInterval = ReadBlockValue(node, "МПИ"),
                CertificateOrSerialNumber = ReadBlockValue(node, "Cвидетельство завод. номер")
                    ?? ReadBlockValue(node, "Свидетельство завод. номер"),
                DetailUrl = ReadDetailUrl(node, baseUrl),
                DescriptionTypePdfUrl = ReadPdfUrl(node, "/prof/opisanie/", baseUrl),
                MethodologyPdfUrl = ReadPdfUrl(node, "/prof/metodiki/", baseUrl)
            };

            if (!string.IsNullOrWhiteSpace(item.RegistryNumber) || !string.IsNullOrWhiteSpace(item.Name))
            {
                items.Add(item);
            }
        }

        return items;
    }

    private static string ReadBlockValue(HtmlNode root, string header)
    {
        var block = FindBlockByHeader(root, header);
        return HtmlParsingHelpers.ExtractNodeTextExcludingChildParagraph(block);
    }

    private static HtmlNode FindBlockByHeader(HtmlNode root, string header)
    {
        var blocks = root.SelectNodes("./div");
        if (blocks == null)
        {
            return null;
        }

        foreach (var block in blocks)
        {
            var paragraph = block.SelectSingleNode("./p");
            var label = HtmlParsingHelpers.NormalizeLabel(paragraph?.InnerText);
            if (string.Equals(label, header, StringComparison.OrdinalIgnoreCase))
            {
                return block;
            }
        }

        return null;
    }

    private static string ReadDetailUrl(HtmlNode root, string baseUrl)
    {
        var link = root.SelectSingleNode(".//div[contains(@class,'resulttable6')]/a[1]")
                   ?? root.SelectSingleNode(".//div[contains(@class,'resulttable4')]/a[1]");
        return HtmlParsingHelpers.MakeAbsoluteUrl(baseUrl, link?.GetAttributeValue("href", null));
    }

    private static string ReadPdfUrl(HtmlNode root, string marker, string baseUrl)
    {
        var link = root.SelectSingleNode($".//a[contains(@href,'{marker}')]");
        return HtmlParsingHelpers.MakeAbsoluteUrl(baseUrl, link?.GetAttributeValue("href", null));
    }
}