//
// This code is part of Document Solutions for PDF demos.
// Copyright (c) MESCIUS inc. All rights reserved.
//
using System;
using System.IO;
using System.IO.Compression;
using System.Drawing;
using System.Collections.Generic;
using GrapeCity.Documents.Pdf;
using GrapeCity.Documents.Text;
using GrapeCity.Documents.Common;

namespace DsPdfWeb.Demos
{
    // This sample shows how to use the GcPdfDocument.Optimize() method
    // to reduce the size of a PDF by applying various optimization strategies,
    // such as using the optimal compression, using object streams,
    // merging duplicate and removing unused embedded fonts, and so on.
    // For details on the optimization strategies, see the OptimizeDocumentOptions class.
    //
    // This sample extracts the first five pages of a PDF, and then merges those pages
    // into a single new document without applying any optimizations.
    // The sample records the merged PDF's size, then runs Optimize() on that PDF
    // and records the size of the optimized PDF. These results are printed into the
    // PDF returned by the sample, thus illustrating the effect of running Optimize()
    // with most optimization options on (the only option that is not applied is
    // removing embedded fonts, which is not recommended in most cases as it can produce
    // documents not readable on some systems).
    //
    // See also OptimizeFonts and RemoveDuplicateImages.
    public class OptimizePDF
    {
        public int CreatePDF(Stream stream)
        {
            // Create a 5 page non-optimal PDF:
            var srcFn = Path.Combine("Resources", "PDFs", "CompleteJavaScriptBook.pdf");
            var tmpInput = MakeInputFile(srcFn);
            var fiInput = new FileInfo(tmpInput);

            // Create a new PDF, load the source PDF into it, and optimize it:
            var tmpOutput = Path.GetTempFileName();
            var tmpDoc = new GcPdfDocument();
            using (var fs = File.OpenRead(tmpInput))
            {
                tmpDoc.Load(fs);
                var odo = new OptimizeDocumentOptions();
                // Maximize minimization:
                odo.SetForMinimumSize();
                // But do not remove embedded fonts which is not recommended in most cases:
                odo.RemoveEmbeddedFonts = false;
                tmpDoc.Optimize(tmpOutput, odo);
            }
            var fiOutput = new FileInfo(tmpOutput);

            // Record the input and output file sizes in the resultant PDF:
            var doc = new GcPdfDocument();
            Common.Util.AddNote(String.Format(
                "Using the GcPdfDocument.Optimize() method reduced the size of a 5-page PDF from {0:N0} to {1:N0} bytes " +
                "by applying various optimization strategies.\n" +
                "To reproduce these results locally, download and run this sample. You may also modify the sample code to keep the temporary " +
                "input and output files and compare their sizes using a file manager.", fiInput.Length, fiOutput.Length),
                doc.NewPage());
            doc.Save(stream);

            // Clean up (for debugging purposes you may want to change the temp files' extensions to .pdf
            // and keep/examine them, in that case replace the next two lines with the two ChangeExtension calls):
            // File.Move(tmpInput, Path.ChangeExtension(tmpInput, ".pdf"), true);
            // File.Move(tmpOutput, Path.ChangeExtension(tmpOutput, ".pdf"), true);
            File.Delete(tmpInput);
            File.Delete(tmpOutput);

            return doc.Pages.Count;
        }

        static string MakeInputFile(string inFn)
        {
            var indoc = new GcPdfDocument();
            using var fs = File.OpenRead(inFn);
            indoc.Load(fs);

            // Create 5 PDFs from the first 5 pages of the source document:
            var pageCount = 5;
            var docs = new List<GcPdfDocument>(pageCount);
            for (int i = 0; i < pageCount; ++i)
            {
                var outdoc = new GcPdfDocument();
                outdoc.MergeWithDocument(indoc, new MergeDocumentOptions() { PagesRange = new OutputRange(i + 1, i + 1) });
                docs.Add(outdoc);
            }
            // Merge the PDFs into a single document:
            var doc = new GcPdfDocument();
            foreach (var d in docs)
                doc.MergeWithDocument(d);

            // Save the resultant PDF in a temp file:
            var outFn = Path.GetTempFileName();
            doc.Save(outFn);
            return outFn;
        }
    }
}