EditTextCommand.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Threading.Tasks;
using Waher.Runtime.IO;
using Waher.Runtime.Language;
using Waher.Things;
using Waher.Things.Attributes;
using Waher.Things.Queries;
 
namespace Waher.Service.IoTBroker.Sources.ProgramData
{
    public class EditTextCommand : ICommand
    {
        private readonly ProgramDataFile fileNode;
        private readonly string contentType;
 
        public EditTextCommand(ProgramDataFile FileNode)
        {
            this.fileNode = FileNode;
            this.contentType = FileNode.ContentType;
 
            byte[] Bin = File.ReadAllBytes(FileNode.FileName);
            Encoding Encoding = Strings.GetEncoding(Bin, Encoding.UTF8, out int BomLength);
 
            string s = Encoding.GetString(Bin, BomLength, Bin.Length - BomLength);
            string[] Rows = s.Replace("\r\n", "\n").Replace('\r', '\n').Split('\n');
 
            this.Content = Rows;
            this.Encoding = Encoding.BodyName;
        }
 
        [Page(7, "File System", 100)]
        [Header(30, "Text Content:")]
        [ToolTip(31, "Text content in file.")]
        [Required]
        [DynamicContentType(nameof(GetContentType))]
        public string[] Content { get; set; }
 
        [Page(7, "File System", 100)]
        [Header(32, "Text Encoding:")]
        [ToolTip(33, "Encoding used to store text in file.")]
        [Required]
        [DynamicOptions(nameof(GetEncodingOptions))]
        public string Encoding { get; set; }
 
        public OptionAttribute[] GetEncodingOptions()
        {
            List<OptionAttribute> Encodings = new List<OptionAttribute>();
 
            foreach (EncodingInfo Encoding in System.Text.Encoding.GetEncodings())
                Encodings.Add(new OptionAttribute(Encoding.Name));
 
            return Encodings.ToArray();
        }
 
        public ContentTypeAttribute GetContentType()
        {
            return new ContentTypeAttribute(this.contentType);
        }
 
        public string CommandID => "EditText";
 
        public CommandType Type => CommandType.Parametrized;
 
        public string SortCategory => "Edit";
 
        public string SortKey => "Text";
 
        public Task<string> GetNameAsync(Language Language) => Language.GetStringAsync(typeof(ProgramDataSource), 29, "Edit File...");
 
        public Task<string> GetConfirmationStringAsync(Language Language) => Task.FromResult(string.Empty);
 
        public Task<string> GetFailureStringAsync(Language Language) => Task.FromResult(string.Empty);
 
        public Task<string> GetSuccessStringAsync(Language Language) => Task.FromResult(string.Empty);
 
        public Task<bool> CanExecuteAsync(RequestOrigin Caller)
        {
            return Task.FromResult(Caller.HasPrivilege("Source." + ProgramDataSource.SourceID + "Command." + this.CommandID));
        }
 
        public async Task ExecuteCommandAsync()
        {
            Encoding Encoding = System.Text.Encoding.GetEncoding(this.Encoding)
                ?? throw new ArgumentException("Invalid encoding.", nameof(this.Encoding));
 
            StringBuilder sb = new StringBuilder();
            bool First = true;
 
            foreach (string Row in this.Content)
            {
                if (First)
                    First = false;
                else
                    sb.AppendLine();
 
                sb.Append(Row);
            }
 
            string Text = sb.ToString();
            byte[] Bin = Encoding.GetBytes(Text);
            byte[] Bom = Encoding.GetPreamble();
            bool HasBom = EditTextCommand.HasBom(Bin, Bom);
 
            using FileStream fs = File.OpenWrite(this.fileNode.FileName);
            
            if (!HasBom)
                await fs.WriteAsync(Bom, 0, Bom.Length);
 
            await fs.WriteAsync(Bin, 0, Bin.Length);
            await fs.FlushAsync();
 
            fs.SetLength(fs.Position);
        }
 
        internal static bool HasBom(byte[] Bin, byte[] Bom)
        {
            int i, c = Bom.Length;
 
            if (c > Bin.Length)
                return false;
            else if (c == 0)
                return true;
            else
            {
                bool HasBom = true;
 
                for (i = 0; i < c; i++)
                {
                    if (Bom[i] != Bin[i])
                    {
                        HasBom = false;
                        break;
                    }
                }
 
                return HasBom;
            }
        }
 
        public Task StartQueryExecutionAsync(Query Query, Language Language) => this.ExecuteCommandAsync();
 
        public ICommand Copy()
        {
            return new EditTextCommand(this.fileNode);
        }
    }
}