using System;
using System.IO;
using System.Diagnostics;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Linq;
using System.Reflection;
using System.Reflection.Metadata;
using System.Reflection.PortableExecutable;
using System.Reflection.Metadata.Ecma335;
using System.Text;

using AtomicEngine;

using File = System.IO.File;

namespace AtomicTools
{

    class AssemblyInspector
    {

        Dictionary<string, InspectorEnum> InspectorEnums = new Dictionary<string, InspectorEnum>();
        Dictionary<string, InspectorComponent> InspectorComponents = new Dictionary<string, InspectorComponent>();

        PEReader peFile;
        MetadataReader metaReader;

        public AssemblyInspector()
        {

        }

        public string DumpToJSON()
        {
            var dict = new Dictionary<string, object>();

            var enumList = new List<object>();
            var componentList = new List<object>();

            foreach (var entry in InspectorEnums)
            {
                enumList.Add(entry.Value.GetJSONDict());
            }

            foreach (var entry in InspectorComponents)
            {
                componentList.Add(entry.Value.GetJSONDict());
            }

            dict["enums"] = enumList;
            dict["components"] = componentList;

            return MiniJSON.Json.Serialize(dict);

        }

        public void Inspect(String pathToAssembly)
        {

            using (var stream = File.OpenRead(pathToAssembly))
            using (peFile = new PEReader(stream))
            {

                metaReader = peFile.GetMetadataReader();

                ParseEnums();
                ParseComponents();
            }

        }

        void ParseComponents()
        {

            foreach (var handle in metaReader.TypeDefinitions)
            {

                var typeDef = metaReader.GetTypeDefinition(handle);

                // Is this a generic type?
                var genericParams = typeDef.GetGenericParameters();
                if (genericParams.Count != 0)
                    continue;

                var typeName = metaReader.GetString(typeDef.Name);

                var baseTypeHandle = typeDef.BaseType;

                // Work up to base reference (ie defined outside this assembly)
                while (baseTypeHandle.Kind == HandleKind.TypeDefinition)
                {
                    var baseTypeDef = metaReader.GetTypeDefinition((TypeDefinitionHandle)baseTypeHandle);
                    // No way to predetermine if .BaseType is valid
                    try
                    {
                        baseTypeHandle = baseTypeDef.BaseType;
                    }
                    catch (Exception) { break; }
                }

                if (baseTypeHandle.Kind == HandleKind.TypeReference)
                {

                    var typeRef = metaReader.GetTypeReference((TypeReferenceHandle)baseTypeHandle);

                    var baseName = metaReader.GetString(typeRef.Name);

                    if (baseName != "CSComponent")
                        continue;

                    var inspector = new CSComponentInspector(typeDef, peFile, metaReader);

                    var icomponent = inspector.Inspect();

                    if (icomponent != null)
                        InspectorComponents[icomponent.Name] = icomponent;
                }
            }
        }


        void ParseEnums()
        {
            foreach (var handle in metaReader.TypeDefinitions)
            {

                var typeDef = metaReader.GetTypeDefinition(handle);

                var baseTypeHandle = typeDef.BaseType;

                if (baseTypeHandle.Kind == HandleKind.TypeReference)
                {
                    var typeRef = metaReader.GetTypeReference((TypeReferenceHandle)baseTypeHandle);

                    if (metaReader.GetString(typeRef.Name) == "Enum")
                    {
                        ParseEnum(typeDef);
                    }
                }
            }
        }

        void ParseEnum(TypeDefinition enumTypeDef)
        {

            // TODO: verify that int32 is the enums storage type for constant read below

            InspectorEnum ienum = new InspectorEnum();

            ienum.Name = metaReader.GetString(enumTypeDef.Name);

            InspectorEnums[ienum.Name] = ienum;

            var fields = enumTypeDef.GetFields();

            foreach (var fieldHandle in fields)
            {

                var inspectorField = new InspectorField();

                var fieldDef = metaReader.GetFieldDefinition(fieldHandle);

                if ((fieldDef.Attributes & FieldAttributes.HasDefault) != 0)
                {

                    var constantHandle = fieldDef.GetDefaultValue();
                    var constant = metaReader.GetConstant(constantHandle);

                    BlobReader constantReader = metaReader.GetBlobReader(constant.Value);

                    ienum.Values[metaReader.GetString(fieldDef.Name)] = constantReader.ReadInt32();

                }
            }

            return;

        }
    }

    internal class InspectorEnum
    {
        public String Name;
        public Dictionary<string, int> Values = new Dictionary<string, int>();

        public Dictionary<string, object> GetJSONDict()
        {
            var dict = new Dictionary<string, object>();
            dict["name"] = Name;
            dict["values"] = Values;
            return dict;
        }
    }

    internal class InspectorComponent
    {
        public String Name;
        public String Namespace;
        public Dictionary<string, InspectorField> Fields = new Dictionary<string, InspectorField>();

        public Dictionary<string, object> GetJSONDict()
        {
            var dict = new Dictionary<string, object>();

            dict["name"] = Name;
            dict["namespace"] = Namespace;

            var fieldList = new List<object>();

            foreach (var entry in Fields)
            {
                fieldList.Add(entry.Value.GetJSONDict());
            }

            dict["fields"] = fieldList;

            return dict;
        }
    }

    internal class InspectorField
    {

        public Dictionary<string, object> GetJSONDict()
        {

            var dict = new Dictionary<string, object>();

            dict["isEnum"] = IsEnum;
            dict["isArray"] = IsArray;
            dict["typeName"] = TypeName;
            dict["name"] = Name;
            dict["defaultValue"] = DefaultValue;

            dict["caPos"] = CustomAttrPositionalArgs;
            dict["caNamed"] = CustomAttrNamedArgs;

            return dict;

        }

        public bool IsEnum = false;
        public bool IsArray = false;

        public string TypeName;

        // the Name of the InspectorField
        public string Name;
        // The DefaultValue if supplied
        public string DefaultValue;

        // custom attributes, positional and named
        public List<string> CustomAttrPositionalArgs = new List<string>();
        public Dictionary<string, string> CustomAttrNamedArgs = new Dictionary<string, string>();
    }

}