//------------------------------------------------------------------------------
// <copyright file="LicFileLicenseProvider.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>                                                                
//------------------------------------------------------------------------------

namespace System.ComponentModel {
    using System;
    using System.ComponentModel.Design;
    using System.Diagnostics;
    using System.Globalization;
    using System.IO;
    using System.Reflection;
    using System.Runtime.Remoting;
    using System.Security.Permissions;

    /// <include file='doc\LicFileLicenseProvider.uex' path='docs/doc[@for="LicFileLicenseProvider"]/*' />
    /// <devdoc>
    /// <para>Provides an implementation of a <see cref='System.ComponentModel.LicenseProvider'/>. The provider works in
    ///    a similar fashion to Microsoft .NET Framework standard licensing module.</para>
    /// </devdoc>
    [HostProtection(SharedState = true)]
    public class LicFileLicenseProvider : LicenseProvider {

        /// <include file='doc\LicFileLicenseProvider.uex' path='docs/doc[@for="LicFileLicenseProvider.IsKeyValid"]/*' />
        /// <devdoc>
        /// <para>Determines if the key retrieved by the <see cref='System.ComponentModel.LicFileLicenseProvider.GetLicense'/> method is valid 
        ///    for the specified type.</para>
        /// </devdoc>
        protected virtual bool IsKeyValid(string key, Type type) {
            if (key != null) {
                return key.StartsWith(GetKey(type));
            }
            return false;
        }

        /// <include file='doc\LicFileLicenseProvider.uex' path='docs/doc[@for="LicFileLicenseProvider.GetKey"]/*' />
        /// <devdoc>
        ///    Creates a key for the specified type.
        /// </devdoc>
        protected virtual string GetKey(Type type) {
            // This string should not be localized.
            //
            return string.Format(CultureInfo.InvariantCulture, "{0} is a licensed component.", type.FullName);
        }

        /// <include file='doc\LicFileLicenseProvider.uex' path='docs/doc[@for="LicFileLicenseProvider.GetLicense"]/*' />
        /// <devdoc>
        ///    <para>Gets a license for the instance of the component and determines if it is valid.</para>
        /// </devdoc>
        public override License GetLicense(LicenseContext context, Type type, object instance, bool allowExceptions) {
            LicFileLicense lic = null;

            Debug.Assert(context != null, "No context provided!");
            if (context != null) {
                if (context.UsageMode == LicenseUsageMode.Runtime) {
                    string key = context.GetSavedLicenseKey(type, null);
                    if (key != null && IsKeyValid(key, type)) {
                        lic = new LicFileLicense(this, key);
                    }
                }

                if (lic == null) {
                    string modulePath = null;

                    if (context != null) {
                        ITypeResolutionService resolver = (ITypeResolutionService)context.GetService(typeof(ITypeResolutionService));
                        if (resolver != null) {
                            modulePath = resolver.GetPathOfAssembly(type.Assembly.GetName());
                        }
                    }

                    if (modulePath == null) {
                        modulePath = type.Module.FullyQualifiedName;
                    }

                    string moduleDir = Path.GetDirectoryName(modulePath);
                    string licenseFile = moduleDir + "\\" + type.FullName + ".lic";

                    Debug.WriteLine("Looking for license in: " + licenseFile);
                    if (File.Exists(licenseFile)) {
                        Stream licStream = new FileStream(licenseFile, FileMode.Open, FileAccess.Read, FileShare.Read);
                        StreamReader sr = new StreamReader(licStream);
                        string s = sr.ReadLine();
                        sr.Close();
                        if (IsKeyValid(s, type)) {
                            lic = new LicFileLicense(this, GetKey(type));
                        }
                    }

                    if (lic != null) {
                        context.SetSavedLicenseKey(type, lic.LicenseKey);
                    }
                }

            }
            return lic;
        }

        private class LicFileLicense : License {
            private LicFileLicenseProvider owner;
            private string key;

            public LicFileLicense(LicFileLicenseProvider owner, string key) {
                this.owner = owner;
                this.key = key;
            }
            public override string LicenseKey { 
                get {
                    return key;
                }
            }
            public override void Dispose() {
                GC.SuppressFinalize(this);
            }
        }
    }

}