using System.Collections.Generic;
using System.IO;
using System.Linq;
using Sharpmake;
using Configuration = Sharpmake.Project.Configuration;

namespace JustDance.Tools.Helpers
{
    /// <summary>
    /// Creates ntfs hard link to references instead of copying them locally,
    /// in order to improve the build time and reduces the output size.
    /// </summary>
    /// <remarks>Should be called after all the projects have been resolved.</remarks>
    internal static class CopyLocalOptimizer
    {
        public static void ConvertCopiesIntoHardlinks(this Project project)
        {
            foreach (var configuration in project.Configurations)
            {
                configuration.ConvertCopiesIntoHardlinks();
            }
        }

        private static void ConvertCopiesIntoHardlinks(this Configuration configuration)
        {
            var dependencies = new HashSet<Configuration>();
            var mklinker = Path.Combine(Globals.BranchRoot, @"extern\mklinker\mklinker.exe");
            CollectDependenciesRecursive(dependencies, configuration);

            var filesToCopy = dependencies.SelectMany(GetFilesToCopy).Concat(GetReferencesByPath(configuration));

            foreach (var toCopy in filesToCopy)
            {
                var sourceFile = toCopy.Source;
                var targetFile = Path.Combine(configuration.TargetPath, toCopy.RelativePath);

                // C# supports a single declaration of post build events, we must replace the target
                // configuration with its corresponding macro.
                var postBuild = string.Format("\"{0}\" \"{1}\" \"{2}\"", mklinker, targetFile, sourceFile);
                postBuild = postBuild.Replace(string.Format("\\{0}\\", configuration.Target.Name), "\\$(ConfigurationName)\\");

                configuration.EventPostBuild.Add(postBuild);
            }
        }

        private static IEnumerable<FileToCopy> GetFilesToCopy(Configuration dependency)
        {
            var toCopy = new List<FileToCopy>();

            toCopy.AddRange(GetCustomBuildActionFiles(dependency));
            toCopy.AddRange(GetReferencesByPath(dependency));

            toCopy.Add(FileToCopy.Create(Path.Combine(dependency.TargetPath, dependency.TargetFileFullName + GetAssemblyExtension(dependency))));
            toCopy.Add(FileToCopy.Create(Path.Combine(dependency.TargetPath, dependency.TargetFileFullName + ".pdb")));

            return toCopy;
        }

        private static IEnumerable<FileToCopy> GetReferencesByPath(Configuration dependency)
        {
            return dependency.ReferencesByPath.Select(file => Util.PathGetAbsolute(dependency.TargetPath, file)).Select(FileToCopy.Create);
        }

        /// <summary>
        /// Returns the files in the project that are copied to output. They should be relative to their folder.
        /// </summary>
        private static IEnumerable<FileToCopy> GetCustomBuildActionFiles(Configuration dependency)
        {
            var project = dependency.Project as CSharpProject;
            
            if (project != null)
            {
                return from additionalFile in project.AdditionalContentAlwaysCopy.Concat(project.AdditionalContentCopyIfNewer)
                    let absolutePath = Path.Combine(project.SourceRootPath, additionalFile)
                    from file in ExpandWildcards(absolutePath)
                    select new FileToCopy
                    {
                        Source = file,
                        RelativePath = Util.PathGetRelative(project.SourceRootPath, file)
                    };
            }
            return new FileToCopy[0];
        }

        /// <summary>
        /// Expands the * into their files.
        /// </summary>
        private static IEnumerable<string> ExpandWildcards(string sourceFile)
        {
            if (sourceFile.EndsWith("*"))
            {
                var directory = sourceFile.TrimEnd('*');
                if (Directory.Exists(directory))
                {
                    foreach (var file in Directory.GetFiles(directory, "*", SearchOption.AllDirectories))
                    {
                        yield return file;
                    }
                }
            }
            else
            {
                yield return sourceFile;
            }
        }
    
        private static void CollectDependenciesRecursive(HashSet<Configuration> configurations, Configuration configuration)
        {
            foreach (var dependency in configuration.ResolvedDependencies)
            {
                if (configurations.Add(dependency))
                {
                    CollectDependenciesRecursive(configurations, dependency);
                }
            }
        }

        private static string GetAssemblyExtension(Configuration dependency)
        {
            return (dependency.Output == Configuration.OutputType.Exe ||
                    dependency.Output == Configuration.OutputType.DotNetWindowsApp ||
                    dependency.Output == Configuration.OutputType.DotNetConsoleApp) ? ".exe" : ".dll";
        }

        private struct FileToCopy
        {
            /// <summary>
            /// The full path of the sourceFolder file.
            /// </summary>
            public string Source { get; set; }
            /// <summary>
            /// The destination relative to the output.
            /// </summary>
            public string RelativePath { get; set; }

            public static FileToCopy Create(string source)
            {
                return new FileToCopy
                {
                    Source = source,
                    RelativePath = Path.GetFileName(source)
                };
            }
        }
    }
}