using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Xml;

using Verse;

namespace LoadOnDemand
{
    public class PatchOperationLoadOnDemand : PatchOperation
    {
        bool required;
        bool tested;

        public List<string> mods;
        public List<string> folders;

        protected override bool ApplyWorker (XmlDocument xml)
        {
            if (tested) return false;

            tested = true;

            if (mods.NullOrEmpty () || folders.NullOrEmpty()) {
                return false;
            }

            required = ModLister.AllInstalledMods.Select (mod => mod.Name).Any (name => mods.Contains (name));

            return true;
        }

        public override void Complete (string modIdentifier)
        {
            if (required) {
                foreach (var folder in folders) {
                    Log.Message (modIdentifier + " :: Loading " + folder + " on demand");

                    LoadDefs (LoadedModManager.GetMod<LoadOnDemand> ().Content, folder);
                }
            }

            base.Complete (modIdentifier);
        }

        // Adapted from ModContentPack.LoadDefs
        public void LoadDefs (ModContentPack content, string folder)
        {
            string path = Path.Combine (Path.Combine (content.RootDir, "DefsOnDemand/"), folder);
            if (!Directory.Exists (path)) {
                Log.Warning (string.Format("{0} is trying to load non-existant folder DefsOnDemand/{1}", content.Identifier, folder));

                return;
            }

            var list = DirectXmlLoader.XmlAssetsInModFolder (content, "DefsOnDemand/" + folder).ToList<LoadableXmlAsset> ();
            foreach (var xmlAsset in list) {
                foreach (var patch in content.Patches) {
                    patch.Apply (xmlAsset.xmlDoc);
                }
            }
            for (int i = 0; i < list.Count; i++) {
                if (list [i] == null || list [i].xmlDoc == null || list [i].xmlDoc.DocumentElement == null) {
                    Log.Error (string.Format ("{0}: unknown parse failure", list [i].fullFolderPath + "/" + list [i].name));
                } else if (list [i].xmlDoc.DocumentElement.Name != "Defs") {
                    Log.Error (string.Format ("{0}: root element named {1}; should be named Defs", list [i].fullFolderPath + "/" + list [i].name, list [i].xmlDoc.DocumentElement.Name));
                }
                XmlInheritance.TryRegisterAllFrom (list [i], content);
            }
            XmlInheritance.Resolve ();

            for (int j = 0; j < list.Count; j++) {
                var defPackage = new DefPackage (list [j].name, folder);
                foreach (var def in DirectXmlLoader.AllDefsFromAsset (list [j])) {
                    defPackage.defs.Add (def);
                }
                content.AddDefPackage (defPackage);
            }
        }
    }
}