using System.Text;

namespace Processor.Generators;

public class GodotCSV : IGenerator
{
    private static readonly List<string> CULTURE_CODES = new();

    #region Implementation of IGenerator

    /// <inheritdoc />
    public async Task<ProcessorResult<long>> GenerateAsync()
    {
        const string filename = "I18N.csv";
        const char delimiter = ',';
        
        var destPath = await AppSettings.GetGeneratorGodotDestinationPath();
        destPath = Environment.ExpandEnvironmentVariables(destPath);
        long destBytesWritten = 0;
        
        var pathFinal = Path.Join(destPath, filename);
        var pathTemp = Path.Join(destPath, filename + ".gen");
        var issueFinal = string.Empty;

        try
        {
            if(File.Exists(pathTemp))
                File.Delete(pathTemp);
        }
        catch (IOException e)
        {
            return new ProcessorResult<long>(0, false, $"Cannot delete the temporary file: '{e.Message}'. Hint: Is the ransomware protection enabled in your Windows system? If so, please make sure that the I18N Commander has write permission.");
        }

        CULTURE_CODES.Clear();
        var cultures = await AppSettings.GetCultureInfos();
        foreach (var (code, _) in cultures.OrderBy(n => n.Code))
            CULTURE_CODES.Add(code);
        
        if (CULTURE_CODES.Count == 0)
            return new ProcessorResult<long>(0, true, string.Empty);

        try
        {
            await using var fileStream = new FileStream(pathTemp, FileMode.CreateNew, FileAccess.Write, FileShare.None);
            await using var writer = new StreamWriter(fileStream, Encoding.UTF8);

            // Write the header:
            await writer.WriteLineAsync($"keys{delimiter}{string.Join(delimiter, CULTURE_CODES)}");
            
            //
            // Iterate through all sections and text elements:
            //
            var sectionDepth = await SectionProcessor.GetDepth();
            foreach (var sectionLayer in Enumerable.Range(0, sectionDepth + 1))
            {
                var sections = await SectionProcessor.LoadLayer(sectionLayer);
                foreach (var section in sections.OrderBy(n => n.DataKey))
                foreach (var textElement in section.TextElements.OrderBy(n => n.Code))
                {
                    // Get the key for this text element:
                    var key = await TextElementProcessor.GetKey(textElement.Id);
                    
                    // Write the path to the text element as key:
                    await writer.WriteAsync($"{key}{delimiter}");
                    
                    // Load all translations:
                    var translations = textElement.Translations.DistinctBy(n => n.Culture).ToDictionary(translation => translation.Culture, translation => translation.Text);
                    
                    // Iterate through all text elements and write the translations out:
                    for (var cultureIndex = 0; cultureIndex < CULTURE_CODES.Count; cultureIndex++)
                    {
                        var cultureCode = CULTURE_CODES[cultureIndex];
                        var cultureText = translations.TryGetValue(cultureCode, out var text) ? text : string.Empty;
                        
                        // Write the text with delimiter or only the text in case of the last column:
                        if (cultureIndex < CULTURE_CODES.Count - 1)
                            await writer.WriteAsync($@"""{Escape4CSV(cultureText)}""{delimiter}");
                        else
                            await writer.WriteLineAsync($@"""{Escape4CSV(cultureText)}""");
                    }
                }
            }
        }
        catch(IOException e)
        {
            // Happens, e.g. when the ransomware protection on Windows is active and
            // the I18N commander is not on the exclusion list.
            return new ProcessorResult<long>(0, false, $"Cannot write the generator's result file: '{e.Message}'. Hint: Is the ransomware protection enabled in your Windows system? If so, please make sure that the I18N Commander has write permission.");
        }
        finally
        {
            if (File.Exists(pathTemp))
            {
                destBytesWritten = new FileInfo(pathTemp).Length;
                if (destBytesWritten > 0)
                {
                    try
                    {
                        if (File.Exists(pathFinal))
                            File.Delete(pathFinal);

                        File.Move(pathTemp, pathFinal);
                    }
                    catch (IOException e)
                    {
                        // Happens when the file is still in use by the compiler, the IDE, etc.
                        // Depends on the timing, this happens sometimes. We ignore it, though.
                        issueFinal = e.Message;
                    }
                }
            }
        }
        
        if(string.IsNullOrWhiteSpace(issueFinal))
            return new ProcessorResult<long>(destBytesWritten, true, string.Empty);
        else
            return new ProcessorResult<long>(0, false, $"Cannot move the generator's result file to the destination: '{issueFinal}'. Hint: Is the ransomware protection enabled in your Windows system? If so, please make sure that the I18N Commander has write permission.");
    }
    
    private static string Escape4CSV(string text)
    {
        if (string.IsNullOrWhiteSpace(text))
            return string.Empty;

        var sb = new StringBuilder(text.Length);
        foreach (var c in text)
        {
            if (c == '"')
                sb.Append(@""""""); // quoted double quote, i.e. prints ""
            else
                sb.Append(c);
        }

        return sb.ToString();
    }

    #endregion
}