using System;
using System.Collections.Generic;
using System.Reflection;
using System.Xml;

namespace UnityEditor.AddressableAssets.Build
{
    /// <summary>
    /// This can be used to create a LinkXml for your build.  This will ensure that the desired runtime types are packed into the build.
    /// </summary>
    public class LinkXmlGenerator
    {
        Dictionary<Type, Type> m_TypeConversion = new Dictionary<Type, Type>();
        HashSet<Type> m_Types = new HashSet<Type>();

        /// <summary>
        /// Add runtime type to the LinkXml Generator.
        /// </summary>
        /// <param name="types">The desired runtime types.</param>
        public void AddTypes(params Type[] types)
        {
            if (types == null)
                return;
            foreach (var t in types)
                AddTypeInternal(t);
        }

        /// <summary>
        /// Add runtime type to the LinkXml Generator.
        /// </summary>
        /// <param name="types">The desired runtime types.</param>
        public void AddTypes(IEnumerable<Type> types)
        {
            if (types == null)
                return;
            foreach (var t in types)
                AddTypeInternal(t);
        }

        private void AddTypeInternal(Type t)
        {
            if (t == null)
                return;
            
            Type convertedType;
            if (m_TypeConversion.TryGetValue(t, out convertedType))
                m_Types.Add(convertedType);
            else
                m_Types.Add(t);
        }

        /// <summary>
        /// Setup runtime type conversion
        /// </summary>
        /// <param name="a">Convert from type.</param>
        /// <param name="b">Convert to type.</param>
        public void SetTypeConversion(Type a, Type b)
        {
            m_TypeConversion[a] = b; 
        }

        /// <summary>
        /// Save the LinkXml to the specified path.
        /// </summary>
        /// <param name="path">The path to save the linker xml file.</param>
        public void Save(string path)
        {
            var assemblyMap = new Dictionary<Assembly, List<Type>> ();
            foreach (var t in m_Types)
            {
                var a = t.Assembly;
                List<Type> types;
                if (!assemblyMap.TryGetValue(a, out types))
                    assemblyMap.Add(a, types = new List<Type>());
                types.Add(t);
            }
            XmlDocument doc = new XmlDocument();
            var linker = doc.AppendChild(doc.CreateElement("linker"));
            foreach (var k in assemblyMap)
            {
                var assembly = linker.AppendChild(doc.CreateElement("assembly"));
                var attr = doc.CreateAttribute("fullname");
                attr.Value = k.Key.FullName;
                if (assembly.Attributes != null)
                {
                    assembly.Attributes.Append(attr);

                    //TODO - this is a temporary fix to deal with iOS stripping. 
                    if (k.Key.FullName.Contains("Addressables") || k.Key.FullName.Contains("ResourceManager"))
                    {
                        var preserveAssembly = doc.CreateAttribute("preserve");
                        preserveAssembly.Value = "all";
                        assembly.Attributes.Append(preserveAssembly);
                    }
                    
                    foreach (var t in k.Value)
                    {
                        var typeEl = assembly.AppendChild(doc.CreateElement("type"));
                        var tattr = doc.CreateAttribute("fullname");
                        tattr.Value = t.FullName;
                        if (typeEl.Attributes != null)
                        {
                            typeEl.Attributes.Append(tattr);
                            var pattr = doc.CreateAttribute("preserve");
                            pattr.Value = "all";
                            typeEl.Attributes.Append(pattr);
                        }
                    }
                }
            }
            doc.Save(path);
        }
    }
}