using System;
using System.Collections.Generic;

using FluentValidation;

using MfGames.Gallium;

using Serilog;

using Zio;

namespace MfGames.Nitride.IO.Directories;

/// <summary>
/// A Nitride operation that removes the contents of a directory but not
/// the directory itself. This is used because some tools don't handle
/// when the root directory is removed.
/// This will create the top-level directory if it doesn't exist.
/// </summary>
[WithProperties]
public partial class ClearDirectory : FileSystemOperationBase, IOperation
{
    private readonly IValidator<ClearDirectory> validator;

    public ClearDirectory(
        IValidator<ClearDirectory> validator,
        IFileSystem fileSystem,
        ILogger logger)
        : base(fileSystem)
    {
        this.Logger = logger;
        this.validator = validator;
    }

    public ILogger Logger { get; set; }

    /// <summary>
    /// Gets or sets the path of the directory to clear.
    /// </summary>
    public UPath? Path { get; set; }

    public IEnumerable<Entity> Run()
    {
        return this.Run(new List<Entity>());
    }

    /// <inheritdoc />
    public override IEnumerable<Entity> Run(IEnumerable<Entity> input)
    {
        this.validator.ValidateAndThrow(this);

        // This really isn't an input-type of operation, but it can fit
        // inside one to keep a pattern.
        if (!this.Path.HasValue)
        {
            throw new InvalidOperationException(
                nameof(ClearDirectory)
                + "cannot be used without setting the path either by the"
                + "factory method, the constructor, the property, or "
                + "SetPath method.");
        }

        // See if the directory exists. If it doesn't, then we make it.
        UPath path = this.Path.Value;

        if (!this.FileSystem.DirectoryExists(path))
        {
            this.Logger.Information("Creating the directory {Path}", path);
            this.FileSystem.CreateDirectory(path);
        }

        // Clear out the contents.
        IEnumerable<UPath> files = this.FileSystem.EnumerateFiles(path);
        IEnumerable<UPath> directories = this.FileSystem.EnumerateDirectories(path);

        foreach (UPath file in files)
        {
            this.FileSystem.DeleteFile(file);
        }

        foreach (UPath directory in directories)
        {
            this.FileSystem.DeleteDirectory(directory, true);
        }

        // Just pass the input on.
        return input;
    }

    public ClearDirectory WithFileSystem(IFileSystem value)
    {
        this.FileSystem = value;

        return this;
    }
}