using System;
using System.Linq;
using System.Xml.Serialization;
using System.Collections.Generic;
using System.Text.RegularExpressions;

using Avalonia;

using BFR.Helpers;
using BFR.DataModels;

namespace BFR.Operations
{
    public class Replace : Operation
    {
        public override string Name => nameof(Replace);
        public override string Description => "Replaces the selected part of the file name.";

        public static readonly AvaloniaProperty<ReplaceMode> ModeProperty =
            AvaloniaProperty.Register<MainWindow, ReplaceMode>(nameof(Mode), ReplaceMode.Pattern);
        public ReplaceMode Mode { get => GetValue(ModeProperty); set => SetValue(ModeProperty, value); }

        [XmlIgnore]
        public ReplaceOperationMode[] Modes => ReplaceOperationMode.Modes;

        public string Replacement { get; set; } = "";
        public bool FullName { get; set; } = false;
        public string Pattern { get; set; } = "";
        public bool UseRegex { get; set; } = false;
        public bool UseRegexReplace { get; set; } = false;
        public string Characters { get; set; } = "";
        public int FirstN { get; set; } = 0;
        public int LastN { get; set; } = 0;
        public int FromN { get; set; } = 0;
        public int ToN { get; set; } = 0;

        protected override void ApplyToInternal(IList<FileModel> files)
        {
            // Fail conditions: Various out-of-bounds
            var shortestLength = files.Min(x => FullName ? x.FullName.Length : x.Name.Length);
            if (Mode == ReplaceMode.FirstN && FirstN > shortestLength) throw new OperationException($"First N can't be greater than the shortest file name length ({shortestLength}).");
            if (Mode == ReplaceMode.LastN && LastN > shortestLength) throw new OperationException($"Last N can't be greater than the shortest file name length ({shortestLength}).");
            if (Mode == ReplaceMode.FromNToN && FromN > shortestLength) throw new OperationException($"From N can't be greater than the shortest file name length ({shortestLength}).");
            if (Mode == ReplaceMode.FromNToN && ToN > shortestLength) throw new OperationException($"To N can't be greater than the shortest file name length ({shortestLength}).");
            if (Mode == ReplaceMode.FromNToN && FromN > ToN) throw new OperationException("From N can't be greater than To N.");

            // Regex Failure
            if(Mode == ReplaceMode.Pattern && UseRegex)
                try { "".Replace(Pattern, Replacement, true, false); }
                catch(Exception) { throw new OperationException("Invalid Regex Pattern."); }

            // Apply operation
            foreach(var file in files)
            {
                var newName = FullName ? file.FullName : file.Name;

                newName = Mode switch
                {
                    ReplaceMode.Pattern => newName.Replace(Pattern, Replacement, UseRegex, UseRegexReplace),
                    ReplaceMode.Characters => Characters.Length > 0 ? Regex.Replace(newName, $"[{Characters}]", Replacement.Replace("$", "$$")) : newName,
                    ReplaceMode.FromNToN => Regex.Replace(newName, $"^(.{{{FromN}}}).+(.{{{newName.Length - ToN - 1}}})$", $"$1{Replacement.Replace("$", "$$")}$2"),
                    ReplaceMode.FirstN => Regex.Replace(newName, $"^.{{{FirstN}}}", Replacement.Replace("$", "$$")),
                    ReplaceMode.LastN => Regex.Replace(newName, $".{{{LastN}}}$", Replacement.Replace("$", "$$")),
                    _ => newName
                };

                if (FullName) file.FullName = newName;
                else file.Name = newName;
            }
        }
    }
}