namespace Cake.DotNetVersion
{
    using System;
    using System.Collections.Generic;
    using System.IO;
    using System.Text;
    using Cake.Core;
    using Cake.Core.IO;
    using Cake.Core.Tooling;
    using Newtonsoft.Json;
    using Newtonsoft.Json.Linq;

    /// <summary>
    /// Applies a version to a set of project.json files.
    /// </summary>
    public class DotNetCoreVersionRunner : Tool<DotNetCoreVersionSettings>
    {
        /// <summary>
        /// Initialises a new instance of <see cref="DotNetCoreVersionRunner"/>
        /// </summary>
        /// <param name="fileSystem">The Cake file system.</param>
        public DotNetCoreVersionRunner(IFileSystem fileSystem, ICakeEnvironment environment, IProcessRunner processRunner, IToolLocator toolLocator)
            : base(fileSystem, environment, processRunner, toolLocator)
        {
        }

        public void Run(DotNetCoreVersionSettings settings)
        {
            if (settings == null)
            {
                throw new ArgumentNullException(nameof(settings));
            }

            if (settings.Files != null)
            {
                foreach (var file in settings.Files)
                {
                    RunCore(file, settings.Version);
                }
            }
            else if (settings.File != null)
            {
                RunCore(settings.File, settings.Version);
            }
        }

        protected override IEnumerable<string> GetToolExecutableNames()
        {
            return new string[0];
        }

        protected override string GetToolName()
        {
            return "DotNetCoreVersion";
        }

        private void RunCore(FilePath filePath, string version)
        {
            JObject project;

            using (var file = new FileStream(filePath.FullPath, FileMode.Open))
            using (var stream = new StreamReader(file))
            using (var json = new JsonTextReader(stream))
            {
                project = JObject.Load(json);
            }

            var versionAttr = project.Property("version");
            if (versionAttr == null)
            {
                project.Add("version", new JValue(version));
            }
            else
            {
                versionAttr.Value = version;
            }

            File.WriteAllText(filePath.FullPath, project.ToString(), Encoding.UTF8);
        }
    }
}