using System;

using HtmlAgilityPack;

using System.Collections.Generic;

public class Program

{

    private const string WhitelistedTableClass = "whitelisted-table";

    // description: Showing here how to parse complex web HTML table using HTML Agility Pack C#

    public static void Main()

    {

        // declare object of HtmlDocument

        var html = @"

<h2>Some Title</h2>

​

<h3>Some sub title</h3>

​

<p>A Paragraph of something...</p>

​

<a href='https://google.com'>A link to Google</a>

​

<h3>Example Table</h3>

​

<table class='whitelisted-table'>

    <thead>

      <tr>

        <th>Company</th>

        <th>Contact</th>

        <th>Country</th>

      </tr>

    </thead>

    <tbody>

      <tr>

        <td>Alfreds Futterkiste</td>

        <td>Maria Anders</td>

        <td>Germany</td>

      </tr>

      <tr>

        <td>Centro comercial Moctezuma</td>

        <td>Francisco Chang</td>

        <td>Mexico</td>

      </tr>

    </tbody>

</table>";

        HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();

        doc.LoadHtml(html);

        var thColumns = new List<string>();

        var rows = new List<string>();

        var childNodes = doc.DocumentNode.ChildNodes;

        var texts = ConvertToPlainText(childNodes);

        Console.WriteLine(string.Join("", texts));

    }

    private static ICollection<string> ConvertToPlainText(HtmlNodeCollection nodes)

    {

        var texts = new List<string>();

        foreach (var node in nodes)

        {

            var nodeName = node.Name.ToLowerInvariant();

            switch(nodeName)

            {

                case "style":

                    continue;

                case "br":

                    texts.Add("\n\n");

                    continue;

                default:

                    break;

            }

            // Convert table 

            if (node.HasClass(WhitelistedTableClass))

            {

                texts.Add(ConvertTable(node));

                continue;

            }

​

            if (node.HasChildNodes)

            {

                if (node.Attributes != null && node.Attributes.Count > 0 && node.Attributes.Contains("href"))

                {

                    texts.Add(LinkToTxt(node) + "\n\n");

                }

                else

                {

                    texts.AddRange(ConvertToPlainText(node.ChildNodes));

                }

            }

            else

            {

                var innerText = node.InnerText;

                if (!string.IsNullOrWhiteSpace(innerText))

                {

                    texts.Add(innerText + "\n\n");

                }

            }

        }

​

        return texts;

    }

    private static string LinkToTxt(HtmlNode node)

    {

        var link = node.Attributes["href"].Value;

        var linkLabel = node.InnerText.ToString();

​

        return linkLabel + ": " + link;

    }

    private static string ConvertTable(HtmlNode node)

    {

        var thColumns = new List<string>();

        var rows = new List<string>();

        var trs = node.SelectNodes("tr");

        // Attempt to parse thead 

        var theadColValues = ParseTHead(node);

        if (theadColValues.Count > 0)

        {

            thColumns.AddRange(theadColValues);

        }

        //Loop through child nodes of table

        if (trs != null && trs.Count > 0)

        {

            foreach (var row in trs) 

            {

                // In the event that thead is not present 

                // and <th>'s are only under a <tr>  

                // Loop through th's (column names)

                var ths = row.SelectNodes("th");

                if (ths != null)

                {

                    foreach (var cell in ths) 

                    {

                        thColumns.Add(cell.InnerText);

                    }

                }

​

                //Build list of key value pair 

                var tds = row.SelectNodes("td");

                if (tds != null)

                {

                    int idx = 0;

                    var rowValues = new List<string>();

                    foreach (var cell in tds) 

                    {

                        var columnValue = thColumns[idx];

                        rowValues.Add(columnValue + ": " + cell.InnerText);

                        ++idx;

                    }

                    rows.Add(string.Join("\n", rowValues));

                }

            }

        }

        // Attempt to parse tbody

        var tBodyValues = ParseTBody(thColumns, node);

        if (tBodyValues.Count > 0)

        {

            rows.Add(string.Join("\n\n", tBodyValues));

            return string.Join("", rows);

        }

​

        return string.Join("\n\n", rows);

    }

    // Will return empty array if there is no thead to parse

    private static List<string> ParseTHead(HtmlNode node)

    {

        var thColumns = new List<string>();

        var thead = node.SelectSingleNode("thead");

        if (thead != null)

        {

            var theadTrs = thead.SelectNodes("tr");

            //Loop through child nodes of table

            foreach (var row in theadTrs) 

            {

                var ths = row.SelectNodes("th");

                if (ths != null)

                {

                    foreach (var cell in ths) 

                    {

                        thColumns.Add(cell.InnerText);

                    }

                }

            }

        }

        return thColumns;

    }

    // Will return empty array if there is no tbody to parse

    private static List<string> ParseTBody(List<string> thColumns, HtmlNode node)

    {

        var tBodyValues = new List<string>();

        var tbody = node.SelectSingleNode("tbody");

        if (tbody != null)

        {

            var trs = tbody.SelectNodes("tr");

            //Loop through child nodes of table

            foreach (var row in trs) 

            {

                var rowValues = new List<string>();

                var tds = row.SelectNodes("td");

                if (tds != null)

                {

                    int idx = 0;

                    foreach (var cell in tds) 

                    {

                        var columnValue = thColumns[idx];

                        rowValues.Add(columnValue + ": " + cell.InnerText);

                        ++idx;

                    }

                }

                tBodyValues.Add(string.Join("\n", rowValues));

            }

        }

        return tBodyValues;

    }

}