using System;
using System.IO;
using System.Linq;
using System.Xml.Serialization;

namespace CadParamPluging.Common
{
    public static class TemplateSchemaStore
    {
        private const string FolderName = "CadParamPluging";
        private const string FileName = "template-schemas.xml";

        public static string GetFilePath()
        {
            var dir = Path.Combine(
                Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
                FolderName);
            return Path.Combine(dir, FileName);
        }

        public static TemplateSchemas Load()
        {
            try
            {
                var defaults = TemplateSchemaDefaults.CreateDefault();
                defaults.Normalize();

                var path = GetFilePath();
                if (!File.Exists(path))
                {
                    return defaults;
                }

                using (var stream = File.OpenRead(path))
                {
                    var serializer = new XmlSerializer(typeof(TemplateSchemas));
                    var obj = serializer.Deserialize(stream) as TemplateSchemas;
                    if (obj == null)
                    {
                        return defaults;
                    }

                    obj.Normalize();

                    // Merge: keep local modifications, but add any missing built-in defaults.
                    foreach (var def in defaults.Items ?? Enumerable.Empty<TemplateSchemaDefinition>())
                    {
                        if (def == null || string.IsNullOrWhiteSpace(def.TemplateKey))
                        {
                            continue;
                        }

                        var exists = (obj.Items ?? Enumerable.Empty<TemplateSchemaDefinition>())
                            .Any(x => x != null && string.Equals(x.TemplateKey, def.TemplateKey, StringComparison.OrdinalIgnoreCase));
                        if (!exists)
                        {
                            obj.Items.Add(def);
                        }
                    }

                    obj.Normalize();
                    if (obj.Items != null)
                    {
                        obj.Items = obj.Items
                            .Where(x => x != null && !string.IsNullOrWhiteSpace(x.TemplateKey))
                            .GroupBy(x => x.TemplateKey, StringComparer.OrdinalIgnoreCase)
                            .Select(g => g.First())
                            .ToList();
                    }
                    return obj;
                }
            }
            catch
            {
                return TemplateSchemaDefaults.CreateDefault();
            }
        }

        public static void Save(TemplateSchemas schemas)
        {
            if (schemas == null)
            {
                throw new ArgumentNullException(nameof(schemas));
            }

            schemas.Normalize();

            var path = GetFilePath();
            var dir = Path.GetDirectoryName(path);
            if (!string.IsNullOrEmpty(dir))
            {
                Directory.CreateDirectory(dir);
            }

            var tempPath = path + ".tmp";
            var serializer = new XmlSerializer(typeof(TemplateSchemas));
            using (var stream = File.Create(tempPath))
            {
                serializer.Serialize(stream, schemas);
            }

            if (File.Exists(path))
            {
                File.Delete(path);
            }

            File.Move(tempPath, path);
        }
    }
}