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

namespace DsWordWeb.Demos
{
    // This example shows how to deal with the 'item processed action is required' error.
    public class DataTplFixBatchActionNeeded
    {
        // Code demonstrating the problem:
        GcWordDocument Problem()
        {
            using var oceans = File.OpenRead(Path.Combine("Resources", "data", "oceans.json"));
            var doc = new GcWordDocument();
            doc.DataTemplate.DataSources.Add("ds", oceans);
            doc.Body.Paragraphs.Add("{{ds.name}}");
            // Incorrect: batch processing requires to specify an action that would be invoked
            // after each root data item is processed. Such action could for example save the
            // processed document instance containing the current record's data.
            // Not specifying an action causes an exception:
            doc.DataTemplate.BatchProcess(null);
            return doc;
        }

        // Code demonstrating the fix:
        GcWordDocument Fix()
        {
            using var oceans = File.OpenRead(Path.Combine("Resources", "data", "oceans.json"));
            var doc = new GcWordDocument();
            doc.DataTemplate.DataSources.Add("ds", oceans);
            doc.Body.Paragraphs.Add("{{ds.name}}");
            // Correct: any (even empty) action except null is good enough for the BatchProcess call:
            doc.DataTemplate.BatchProcess(() => { });
            return doc;
        }

        public GcWordDocument CreateDocx()
        {
            GcWordDocument doc;
            try
            {
                // This fails:
                doc = Problem();
            }
            catch (Exception ex)
            {
                // This works:
                doc = Fix();
                // Insert a brief explanation of the problem and the fix into the generated document:
                doc.Body.Paragraphs.Insert(
                    $"The error \"{ex.Message}\" occurred because the BatchProcess() method requires a non-null " +
                    $"action to be specified that would be called as each root data item is processed. " +
                    $"The fix is to specify an action (even an action that does nothing would do). " +
                    $"Note that when the BatchProcess() method returns, the original template document " +
                    $"with data tags rather than actual data is restored.",
                    doc.Styles[BuiltInStyleId.BlockText],
                    InsertLocation.Start);
            }
            return doc;
        }
    }
}