using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.IO;
using AppLimit.NetSparkle.Interfaces;

namespace AppLimit.NetSparkle
{
    public class NetSparkleAssemblyReflectionAccessor : INetSparkleAssemblyAccessor
    {
        private Assembly _assembly;
        private List<Attribute> _assemblyAttributes = new List<Attribute>();

        public NetSparkleAssemblyReflectionAccessor(String assemblyName)
        {
            if (assemblyName == null)
                _assembly = Assembly.GetEntryAssembly();
            else
            {
                String absolutePath = Path.GetFullPath(assemblyName);
                if (!File.Exists(absolutePath))
                    throw new FileNotFoundException();

                _assembly = Assembly.ReflectionOnlyLoadFrom(absolutePath);

                if (_assembly == null)
                    throw new Exception("Unable to load assembly " + absolutePath);                
            }

            // read the attributes            
            foreach (CustomAttributeData data in _assembly.GetCustomAttributesData())
                _assemblyAttributes.Add(CreateAttribute(data));

            if (_assemblyAttributes == null || _assemblyAttributes.Count == 0)
                throw new Exception("Unable to load assembly attributes from " + _assembly.FullName);                                    
        }

        /// <summary>
        /// This methods creates an attribute instance from the attribute data 
        /// information
        /// </summary>
        /// <param name="data"></param>
        /// <returns></returns>
        private Attribute CreateAttribute(CustomAttributeData data)
        {
            var arguments = from arg in data.ConstructorArguments
                            select arg.Value;

            var attribute = data.Constructor.Invoke(arguments.ToArray())
              as Attribute;

            foreach (var namedArgument in data.NamedArguments)
            {
                var propertyInfo = namedArgument.MemberInfo as PropertyInfo;
                if (propertyInfo != null)
                {
                    propertyInfo.SetValue(attribute, namedArgument.TypedValue.Value, null);
                }
                else
                {
                    var fieldInfo = namedArgument.MemberInfo as FieldInfo;
                    if (fieldInfo != null)
                    {
                        fieldInfo.SetValue(attribute, namedArgument.TypedValue.Value);
                    }
                }
            }

            return attribute;
        }

        private Attribute FindAttribute(Type AttributeType)
        {            
            foreach (Attribute attr in _assemblyAttributes)
            {
                if (attr.GetType().Equals(AttributeType))
                    return attr;                                
            }

            throw new Exception("Attribute of type " + AttributeType.ToString() + " does not exists in the assembly " + _assembly.FullName);
        }

        #region Assembly Attribute Accessors

        public string AssemblyTitle
        {
            get
            {
                AssemblyTitleAttribute a = FindAttribute(typeof(AssemblyTitleAttribute)) as AssemblyTitleAttribute;
                return a.Title;                
            }
        }

        public string AssemblyVersion
        {
            get
            {
                return _assembly.GetName().Version.ToString();
            }
        }        

        public string AssemblyDescription
        {
            get
            {
                AssemblyDescriptionAttribute a = FindAttribute(typeof(AssemblyDescriptionAttribute)) as AssemblyDescriptionAttribute;
                return a.Description;                                
            }
        }

        public string AssemblyProduct
        {
            get
            {
                AssemblyProductAttribute a = FindAttribute(typeof(AssemblyProductAttribute)) as AssemblyProductAttribute;
                return a.Product;                                
            }
        }

        public string AssemblyCopyright
        {
            get
            {
                AssemblyCopyrightAttribute a = FindAttribute(typeof(AssemblyCopyrightAttribute)) as AssemblyCopyrightAttribute;
                return a.Copyright;                                                
            }
        }

        public string AssemblyCompany
        {
            get
            {
                AssemblyCompanyAttribute a = FindAttribute(typeof(AssemblyCompanyAttribute)) as AssemblyCompanyAttribute;
                return a.Company;                  
            }
        }
        #endregion
    }
}