adds a way to store what we intend to install

using a package-manifest file.

agsget/agsget/EditorPlugin/AGS.Plugin.AgsGet/AgsGetCore/IntentDescriptor.cs

@@ -0,0 +1,116 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.IO;
+using Newtonsoft.Json;
+
+// this file deals with writing intent as a manifest file
+// when we want to add a package, we add it to the list
+// when we want to remove a package, we remove it from the list
+// we will use this file to store the state of which packages we need to install later on
+// in another step we will get these packages, and figure out dependencies and the order to insert!
+
+namespace AgsGetCore
+{
+    class IntentDescriptor
+    {
+        private const string ManifestFile = "agsget-manifest.json";
+
+        private static string GetManifestFilePath()
+        {
+            return Path.Combine(BaseFiles.GetRunDirectory(), ManifestFile);
+        }
+
+        public static List<MinimalPackageDescriptor> GetManifestAsList()
+        {
+            if (!File.Exists(GetManifestFilePath()))
+            {
+                return new List<MinimalPackageDescriptor>();
+            }
+
+            var manifestAsString = File.ReadAllText(GetManifestFilePath());
+
+            return JsonConvert.DeserializeObject<List<MinimalPackageDescriptor>>(manifestAsString);
+        }
+
+        public static bool AddPackage(string package_id)
+        {
+            var manifestList = GetManifestAsList();
+
+            if (!BaseFiles.ExistsIndexFile())
+            {
+                // we don't even have an index, we need one before adding packages for installation
+                return false;
+            }
+
+            if (!PackageCacheIO.PackageOnIndex(package_id))
+            {
+                // the package_id is wrong or our index is wrong
+                return false;
+            }
+
+            var previouslyAddedPackage = manifestList.Where<MinimalPackageDescriptor>(_mpd =>
+            {
+                return _mpd.id.Equals(package_id.ToLower());
+            });
+
+            if (previouslyAddedPackage.Count() > 0)
+            {
+                return true;
+            }
+
+            var mpd = new MinimalPackageDescriptor();
+            mpd.id = package_id;
+
+            manifestList.Add(mpd);
+
+            string resulting_json_manifest = JsonConvert.SerializeObject(manifestList);
+            const string bkp_ext = ".bkp";
+            string manifest_file = GetManifestFilePath();
+            string bkp_manifest_file = manifest_file + bkp_ext;
+
+            if (File.Exists(manifest_file)) File.Move(manifest_file, bkp_manifest_file);
+            System.IO.File.WriteAllText(manifest_file, resulting_json_manifest);
+            if (File.Exists(bkp_manifest_file)) File.Delete(bkp_manifest_file);
+
+            return true;
+        }
+        public static bool RemovePackage(string package_id)
+        {
+            var manifestList = GetManifestAsList();
+
+            var previouslyAddedPackage = manifestList.Where<MinimalPackageDescriptor>(_mpd =>
+            {
+                return _mpd.id.Equals(package_id.ToLower());
+            });
+
+            if (previouslyAddedPackage.Count() == 0)
+            {
+                return false;
+            }
+
+            manifestList = manifestList.Where<MinimalPackageDescriptor>(_mpd =>
+            {
+                return !_mpd.id.Equals(package_id.ToLower());
+            }).ToList();
+
+            string resulting_json_manifest = JsonConvert.SerializeObject(manifestList);
+            const string bkp_ext = ".bkp";
+            string manifest_file = GetManifestFilePath();
+            string bkp_manifest_file = manifest_file + bkp_ext;
+
+            if (File.Exists(manifest_file)) File.Move(manifest_file, bkp_manifest_file);
+            System.IO.File.WriteAllText(manifest_file, resulting_json_manifest);
+            if (File.Exists(bkp_manifest_file)) File.Delete(bkp_manifest_file);
+
+            return true;
+        }
+
+        public class MinimalPackageDescriptor
+        {
+            public string id { get; set; }
+        }
+    }
+}