// <copyright file="TestImage.cs" company="James Jackson-South">
// Copyright (c) James Jackson-South and contributors.
// Licensed under the Apache License, Version 2.0.
// </copyright>

namespace ImageSharp.Tests
{
    using System;
    using System.Collections.Concurrent;
    using System.Collections.Generic;
    using System.IO;
    using System.Linq;
    using System.Reflection;

    /// <summary>
    /// A test image file.
    /// </summary>
    public class TestFile
    {
        /// <summary>
        /// The test file cache.
        /// </summary>
        private static readonly ConcurrentDictionary<string, TestFile> Cache = new ConcurrentDictionary<string, TestFile>();

        /// <summary>
        /// The formats directory.
        /// </summary>
        private static readonly string FormatsDirectory = GetFormatsDirectory();

        private static readonly object Locker = new object();

        /// <summary>
        /// The image.
        /// </summary>
        private Image<Rgba32> image;

        /// <summary>
        /// The file.
        /// </summary>
        private readonly string file;

        /// <summary>
        /// Initializes a new instance of the <see cref="TestFile"/> class.
        /// </summary>
        /// <param name="file">The file.</param>
        private TestFile(string file)
        {
            this.file = file;
            this.Bytes = File.ReadAllBytes(file);
        }

        /// <summary>
        /// Gets the bytes.
        /// </summary>
        public byte[] Bytes { get; }

        /// <summary>
        /// The file name.
        /// </summary>
        public string FilePath => this.file;

        /// <summary>
        /// The file name.
        /// </summary>
        public string FileName => Path.GetFileName(this.file);

        /// <summary>
        /// The file name without extension.
        /// </summary>
        public string FileNameWithoutExtension => Path.GetFileNameWithoutExtension(this.file);

        /// <summary>
        /// Gets the full qualified path to the file.
        /// </summary>
        /// <param name="file">
        /// The file path.
        /// </param>
        /// <returns>
        /// The <see cref="string"/>.
        /// </returns>
        public static string GetPath(string file)
        {
            return Path.Combine(FormatsDirectory, file);
        }

        /// <summary>
        /// Creates a new test file or returns one from the cache.
        /// </summary>
        /// <param name="file">The file path.</param>
        /// <returns>
        /// The <see cref="TestFile"/>.
        /// </returns>
        public static TestFile Create(string file)
        {
            return Cache.GetOrAdd(file, (string fileName) => new TestFile(GetPath(file)));
        }

        /// <summary>
        /// Gets the file name.
        /// </summary>
        /// <param name="value">The value.</param>
        /// <returns>
        /// The <see cref="string"/>.
        /// </returns>
        public string GetFileName(object value)
        {
            return $"{this.FileNameWithoutExtension}-{value}{Path.GetExtension(this.file)}";
        }

        /// <summary>
        /// Gets the file name without extension.
        /// </summary>
        /// <param name="value">The value.</param>
        /// <returns>
        /// The <see cref="string"/>.
        /// </returns>
        public string GetFileNameWithoutExtension(object value)
        {
            return this.FileNameWithoutExtension + "-" + value;
        }

        /// <summary>
        /// Creates a new image.
        /// </summary>
        /// <returns>
        /// The <see cref="Image"/>.
        /// </returns>
        public Image<Rgba32> CreateImage()
        {
            return new Image<Rgba32>(this.GetImage());
        }

        /// <summary>
        /// Creates a new image.
        /// </summary>
        /// <param name="options">The options for the decoder.</param>
        /// <returns>
        /// The <see cref="Image"/>.
        /// </returns>
        public Image<Rgba32> CreateImage(IDecoderOptions options)
        {
            return Image.Load<Rgba32>(this.Bytes, options);
        }

        private Image<Rgba32> GetImage()
        {
            lock (Locker)
            {
                return this.image ?? (this.image = Image.Load<Rgba32>(this.Bytes));
            }
        }

        /// <summary>
        /// Gets the correct path to the formats directory.
        /// </summary>
        /// <returns>
        /// The <see cref="string"/>.
        /// </returns>
        private static string GetFormatsDirectory()
        {
            var directories = new List<string> {
                 "TestImages/Formats/", // Here for code coverage tests.
                  "tests/ImageSharp.Tests/TestImages/Formats/", // From travis/build script
                  "../../../../../ImageSharp.Tests/TestImages/Formats/", // From Sandbox46
                  "../ImageSharp.Tests/TestImages/Formats/", // From Sandbox46 Program.cs
                  "../../../../TestImages/Formats/",
                  "../../../TestImages/Formats/"
            };

            directories = directories
                .SelectMany(x => new[]
                {
                    Path.GetFullPath(x)
                }).ToList();

            AddFormatsDirectoryFromTestAssebmlyPath(directories);

            string directory = directories.FirstOrDefault(Directory.Exists);

            if (directory != null)
            {
                return directory;
            }

            throw new System.Exception($"Unable to find Formats directory at any of these locations [{string.Join(", ", directories)}]");
        }

        /// <summary>
        /// The path returned by Path.GetFullPath(x) can be relative to dotnet framework directory
        /// in certain scenarios like dotTrace test profiling.
        /// This method calculates and adds the format directory based on the ImageSharp.Tests assembly location.
        /// </summary>
        /// <param name="directories">The directories list</param>
        private static void AddFormatsDirectoryFromTestAssebmlyPath(List<string> directories)
        {
            string assemblyLocation = typeof(TestFile).GetTypeInfo().Assembly.Location;
            assemblyLocation = Path.GetDirectoryName(assemblyLocation);

            if (assemblyLocation != null)
            {
                string dirFromAssemblyLocation = Path.Combine(assemblyLocation, "../../../TestImages/Formats/");
                dirFromAssemblyLocation = Path.GetFullPath(dirFromAssemblyLocation);
                directories.Add(dirFromAssemblyLocation);
            }
        }
    }
}