using System.Collections.Generic;
using System.IO;
using System.IO.Compression;

namespace Follina;

internal class FollinaExtractor
{
    public List<string> ReadFollinaInfectedDocument(string path)
    {
        List<string> hits = new();

        if (string.IsNullOrEmpty(path) == false)
        {
            if (Path.GetExtension(path).ToLower() == ".docx")
            {
                using MemoryStream memoryStream = new();
                using ZipArchive archive = ZipFile.OpenRead(path);
                foreach (ZipArchiveEntry entry in archive.Entries)
                {
                    if (entry.FullName == "word/_rels/document.xml.rels")
                    {
                        using var entryStream = entry.Open();
                        using var streamReader = new StreamReader(entryStream);
                        var text = streamReader.ReadToEnd();

                        int start = text.IndexOf("Target=\"mhtml:");

                        const string prefix = "Target=\"";

                        if (start != -1)
                        {
                            hits.Add(text[(start + prefix.Length)..text.IndexOf("\"", start + prefix.Length)]);
                        }
                    }
                }
            }
            else if (Path.GetExtension(path).ToLower() == ".rtf")
            {
                string text = File.ReadAllText(path);

                int start = text.IndexOf("\\objclass http");

                const string prefix1 = "\\objclass ";
                const string prefix2 = "\\objclass (";

                if (start != -1)
                {
                    hits.Add(text[(start + prefix1.Length)..text.IndexOf("}", start)]);
                }

                start = text.IndexOf("\\objclass (http");

                if (start != -1)
                {
                    hits.Add(text[(start + prefix2.Length)..text.IndexOf("}", start)]);
                }
            }
        }

        return hits;
    }
}