using System.Collections.Generic;
using System.IO;
using System.Linq;
using DotNet.Globbing;
using Gallium;
using Nitride.Contents;
using Zio;

namespace 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>
    public class ReadFiles : FileSystemOperation
    {
        public ReadFiles(IFileSystem fileSystem)
            : base(fileSystem)
        {
        }

        /// <summary>
        /// Primary method for creating a read file.
        /// </summary>
        public delegate ReadFiles Factory(IFileSystem fileSystem);

        /// <summary>
        /// Reads all files from the file system and returns them.
        /// </summary>
        /// <returns>A populated collection of entities.</returns>
        public IEnumerable<Entity> Read(
            UPath path = new(),
            string searchPattern = "*",
            SearchOption search = SearchOption.AllDirectories)
        {
            // Normalize the path.
            path = path == new UPath() ? "/" : path;

            //  Search for the file and wrap the results.
            IEnumerable<FileEntry> files = this.FileSystem
                .EnumerateFileEntries(path, searchPattern, search);
            IEnumerable<Entity> entities = files.Select(this.ToEntity);

            return entities;
        }

        /// <summary>
        /// Reads all files from the file system and returns them.
        /// </summary>
        /// <returns>A populated collection of entities.</returns>
        public IEnumerable<Entity> Read(string glob)
        {
            Glob parsed = Glob.Parse(glob);

            return this.Read(parsed);
        }

        /// <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> Read(Glob glob)
        {
            IEnumerable<FileEntry> files = this.FileSystem
                .EnumerateFileEntries("/", "*.*", SearchOption.AllDirectories)
                .Where(x => glob.IsMatch(x.Path.ToString()));
            IEnumerable<Entity> entities = files.Select(this.ToEntity);

            return entities;
        }

        /// <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;
        }
    }
}