#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange
//
// Copyright (c) 2005-2017 empira Software GmbH, Cologne Area (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

namespace PdfSharp.Pdf.AcroForms
{
    /// <summary>
    /// Represents the signature field.
    /// </summary>
    public sealed class PdfSignatureField : PdfAcroField
    {
        /// <summary>
        /// Initializes a new instance of PdfSignatureField.
        /// </summary>
        internal PdfSignatureField(PdfDocument document)
            : base(document)
        { }

        internal PdfSignatureField(PdfDictionary dict)
            : base(dict)
        { }

        /// <summary>
        /// Predefined keys of this dictionary.
        /// The description comes from PDF 1.4 Reference.
        /// </summary>
        public new class Keys : PdfAcroField.Keys
        {
            /// <summary>
            /// (Optional) The type of PDF object that this dictionary describes; if present,
            /// must be Sig for a signature dictionary.
            /// </summary>
            [KeyInfo(KeyType.Name | KeyType.Optional)]
            public const string Type = "/Type";

            /// <summary>
            /// (Required; inheritable) The name of the signature handler to be used for
            /// authenticating the field’s contents, such as Adobe.PPKLite, Entrust.PPKEF,
            /// CICI.SignIt, or VeriSign.PPKVS.
            /// </summary>
            [KeyInfo(KeyType.Name | KeyType.Required)]
            public const string Filter = "/Filter";

            /// <summary>
            /// (Optional) The name of a specific submethod of the specified handler.
            /// </summary>
            [KeyInfo(KeyType.Name | KeyType.Optional)]
            public const string SubFilter = "/SubFilter";

            /// <summary>
            /// (Required) An array of pairs of integers (starting byte offset, length in bytes)
            /// describing the exact byte range for the digest calculation. Multiple discontinuous
            /// byte ranges may be used to describe a digest that does not include the
            /// signature token itself.
            /// </summary>
            [KeyInfo(KeyType.Array | KeyType.Required)]
            public const string ByteRange = "/ByteRange";

            /// <summary>
            /// (Required) The encrypted signature token.
            /// </summary>
            [KeyInfo(KeyType.String | KeyType.Required)]
            public const string Contents = "/Contents";

            /// <summary>
            /// (Optional) The name of the person or authority signing the document.
            /// </summary>
            [KeyInfo(KeyType.TextString | KeyType.Optional)]
            public const string Name = "/Name";

            /// <summary>
            /// (Optional) The time of signing. Depending on the signature handler, this
            /// may be a normal unverified computer time or a time generated in a verifiable
            /// way from a secure time server.
            /// </summary>
            [KeyInfo(KeyType.Date | KeyType.Optional)]
            public const string M = "/M";

            /// <summary>
            /// (Optional) The CPU host name or physical location of the signing.
            /// </summary>
            [KeyInfo(KeyType.TextString | KeyType.Optional)]
            public const string Location = "/Location";

            /// <summary>
            /// (Optional) The reason for the signing, such as (I agree…).
            /// </summary>
            [KeyInfo(KeyType.TextString | KeyType.Optional)]
            public const string Reason = "/Reason";

            /// <summary>
            /// Gets the KeysMeta for these keys.
            /// </summary>
            internal static DictionaryMeta Meta
            {
                get { return _meta ?? (_meta = CreateMeta(typeof(Keys))); }
            }
            static DictionaryMeta _meta;
        }

        /// <summary>
        /// Gets the KeysMeta of this dictionary type.
        /// </summary>
        internal override DictionaryMeta Meta
        {
            get { return Keys.Meta; }
        }
    }
}
