using System;
using iTextSharp.text.pdf;
using PDFPatcher.Model;

namespace PDFPatcher.Processor
{
	sealed class PageProcessorContext
	{
		/// <summary>正在处理的 PDF 文档。</summary>
		public PdfReader Pdf { get; }

		/// <summary>正在处理的页码。</summary>
		public int PageNumber { get; }

		/// <summary>标记页面内容是否已被更改。</summary>
		public bool IsPageContentModified { get; set; }

		PdfDictionary _Page;
		/// <summary>获取正在处理的页面。</summary>
		public PdfDictionary Page => _Page ??= Pdf.GetPageN(PageNumber);

		PdfPageCommandProcessor _processor;
		/// <summary>获取正在处理的页面指令集合。</summary>
		public IPdfPageCommandContainer PageCommands {
			get {
				if (_processor == null) {
					_processor = new PdfPageCommandProcessor();
					_processor.ProcessContent(PdfReader.GetPageContent(Page), Page.Locate<PdfDictionary>(PdfName.RESOURCES));
				}
				return _processor;
			}
		}

		public PageProcessorContext(PdfReader pdf, int pageNumber) {
			Pdf = pdf;
			PageNumber = pageNumber;
		}

		/// <summary>写入页面指令到当前处理的页面。</summary>
		internal void WritePageCommands() {
			_processor.WritePdfCommands(Pdf, PageNumber);
		}
	}
}