using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

using DotNet.Globbing;

using FluentValidation;

using MfGames.Gallium;

using MfGames.Nitride.Contents;

using Zio;

namespace MfGames.Nitride.IO.Contents;

/// <summary>
/// A module that reads files from the file system and wraps them in an
/// entity with the following components: UPath, IContent.
/// </summary>
[WithProperties]
public partial class ReadFiles : FileSystemOperationBase
{
    private readonly IValidator<ReadFiles> validator;

    public ReadFiles(
        IValidator<ReadFiles> validator,
        IFileSystem fileSystem)
        : base(fileSystem)
    {
        this.validator = validator;
    }

    /// <summary>
    /// Gets or sets the file pattern to retrieve fields. This supports
    /// globbing both "*" and "**" patterns such as "**/*".
    /// </summary>
    public string Pattern { get; set; } = null!;

    /// <summary>
    /// Reads all files from the file system, filtering them out by the
    /// minimatch pattern (as defined by DotNet.Blob).
    /// </summary>
    /// <returns>A populated collection of entities.</returns>
    public IEnumerable<Entity> Run()
    {
        return this.Run(Array.Empty<Entity>());
    }

    /// <summary>
    /// Reads all files from the file system, filtering them out by the
    /// minimatch pattern (as defined by DotNet.Blob).
    /// </summary>
    /// <returns>A populated collection of entities.</returns>
    public override IEnumerable<Entity> Run(IEnumerable<Entity> input)
    {
        this.validator.ValidateAndThrow(this);

        var glob = Glob.Parse(this.Pattern);

        IEnumerable<FileEntry> files = this.FileSystem.EnumerateFileEntries("/", "*", SearchOption.AllDirectories)
            .Where(x => glob.IsMatch(x.Path.ToString()));

        IEnumerable<Entity> entities = files.Select(this.ToEntity);

        return entities;
    }

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

        return this;
    }

    /// <summary>
    /// Creates an entity with the standard components for all Zio-based
    /// files. This attaches the file's path relative to the file system
    /// and a way of accessing the content from the file system.
    /// </summary>
    /// <param name="file">The Zio file entry.</param>
    /// <returns>An Entity with appropriate content.</returns>
    private Entity ToEntity(FileEntry file)
    {
        Entity entity = new Entity().Set(file.Path)
            .SetBinaryContent(new FileEntryBinaryContent(file));

        return entity;
    }
}