// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Xml.Linq;
using System.Xml.Schema;
using DocumentFormat.OpenXml.Packaging;

namespace OpenXmlPowerTools
{
    public partial class WmlDocument
    {
        public WmlDocument SimplifyMarkup(SimplifyMarkupSettings settings)
        {
            return MarkupSimplifier.SimplifyMarkup(this, settings);
        }
    }

    public class SimplifyMarkupSettings
    {
        public bool AcceptRevisions;
        public bool NormalizeXml;
        public bool RemoveBookmarks;
        public bool RemoveComments;
        public bool RemoveContentControls;
        public bool RemoveEndAndFootNotes;
        public bool RemoveFieldCodes;
        public bool RemoveGoBackBookmark;
        public bool RemoveHyperlinks;
        public bool RemoveLastRenderedPageBreak;
        public bool RemoveMarkupForDocumentComparison;
        public bool RemovePermissions;
        public bool RemoveProof;
        public bool RemoveRsidInfo;
        public bool RemoveSmartTags;
        public bool RemoveSoftHyphens;
        public bool RemoveWebHidden;
        public bool ReplaceTabsWithSpaces;
    }

    [SuppressMessage("ReSharper", "InconsistentNaming")]
    public static class MarkupSimplifier
    {
        public static WmlDocument SimplifyMarkup(WmlDocument doc, SimplifyMarkupSettings settings)
        {
            using (var streamDoc = new OpenXmlMemoryStreamDocument(doc))
            {
                using (WordprocessingDocument document = streamDoc.GetWordprocessingDocument())
                    SimplifyMarkup(document, settings);
                return streamDoc.GetModifiedWmlDocument();
            }
        }

        public static void SimplifyMarkup(WordprocessingDocument doc, SimplifyMarkupSettings settings)
        {
            if (settings.RemoveMarkupForDocumentComparison)
            {
                settings.RemoveRsidInfo = true;
                RemoveElementsForDocumentComparison(doc);
            }
            if (settings.RemoveRsidInfo)
                RemoveRsidInfoInSettings(doc);
            if (settings.AcceptRevisions)
                RevisionAccepter.AcceptRevisions(doc);
            foreach (OpenXmlPart part in doc.ContentParts())
                SimplifyMarkupForPart(part, settings);

            if (doc.MainDocumentPart.StyleDefinitionsPart != null)
                SimplifyMarkupForPart(doc.MainDocumentPart.StyleDefinitionsPart, settings);
            if (doc.MainDocumentPart.StylesWithEffectsPart != null)
                SimplifyMarkupForPart(doc.MainDocumentPart.StylesWithEffectsPart, settings);

            if (settings.RemoveComments)
            {
                WordprocessingCommentsPart commentsPart = doc.MainDocumentPart.WordprocessingCommentsPart;
                if (commentsPart != null) doc.MainDocumentPart.DeletePart(commentsPart);

                WordprocessingCommentsExPart commentsExPart = doc.MainDocumentPart.WordprocessingCommentsExPart;
                if (commentsExPart != null) doc.MainDocumentPart.DeletePart(commentsExPart);
            }
        }

        private static void RemoveRsidInfoInSettings(WordprocessingDocument doc)
        {
            DocumentSettingsPart part = doc.MainDocumentPart.DocumentSettingsPart;
            if (part == null) return;

            XDocument settingsXDoc = part.GetXDocument();
            settingsXDoc.Descendants(W.rsids).Remove();
            part.PutXDocument();
        }

        private static void RemoveElementsForDocumentComparison(WordprocessingDocument doc)
        {
            OpenXmlPart part = doc.ExtendedFilePropertiesPart;
            if (part != null)
            {
                XDocument appPropsXDoc = part.GetXDocument();
                appPropsXDoc.Descendants(EP.TotalTime).Remove();
                part.PutXDocument();
            }

            part = doc.CoreFilePropertiesPart;
            if (part != null)
            {
                XDocument corePropsXDoc = part.GetXDocument();
                corePropsXDoc.Descendants(CP.revision).Remove();
                corePropsXDoc.Descendants(DCTERMS.created).Remove();
                corePropsXDoc.Descendants(DCTERMS.modified).Remove();
                part.PutXDocument();
            }

            XDocument mainXDoc = doc.MainDocumentPart.GetXDocument();
            List<XElement> bookmarkStart = mainXDoc
                .Descendants(W.bookmarkStart)
                .Where(b => (string) b.Attribute(W.name) == "_GoBack")
                .ToList();
            foreach (XElement item in bookmarkStart)
            {
                IEnumerable<XElement> bookmarkEnd = mainXDoc
                    .Descendants(W.bookmarkEnd)
                    .Where(be => (int) be.Attribute(W.id) == (int) item.Attribute(W.id));
                bookmarkEnd.Remove();
            }

            bookmarkStart.Remove();
            doc.MainDocumentPart.PutXDocument();
        }

        public static XElement MergeAdjacentSuperfluousRuns(XElement element)
        {
            return (XElement) MergeAdjacentRunsTransform(element);
        }

        public static XElement TransformElementToSingleCharacterRuns(XElement element)
        {
            return (XElement) SingleCharacterRunTransform(element);
        }

        public static void TransformPartToSingleCharacterRuns(OpenXmlPart part)
        {
            // After transforming to single character runs, Rsid info will be invalid, so
            // remove from the part.
            XDocument xDoc = part.GetXDocument();
            var newRoot = (XElement) RemoveRsidTransform(xDoc.Root);
            newRoot = (XElement) SingleCharacterRunTransform(newRoot);
            xDoc.Elements().First().ReplaceWith(newRoot);
            part.PutXDocument();
        }

        public static void TransformToSingleCharacterRuns(WordprocessingDocument doc)
        {
            if (RevisionAccepter.HasTrackedRevisions(doc))
                throw new OpenXmlPowerToolsException(
                    "Transforming a document to single character runs is not supported for " +
                    "a document with tracked revisions.");

            foreach (OpenXmlPart part in doc.ContentParts())
                TransformPartToSingleCharacterRuns(part);
        }

        private static object RemoveCustomXmlAndContentControlsTransform(
            XNode node, SimplifyMarkupSettings simplifyMarkupSettings)
        {
            XElement element = node as XElement;
            if (element != null)
            {
                if (simplifyMarkupSettings.RemoveSmartTags &&
                    element.Name == W.smartTag)
                    return element
                        .Elements()
                        .Select(e =>
                            RemoveCustomXmlAndContentControlsTransform(e,
                                simplifyMarkupSettings));

                if (simplifyMarkupSettings.RemoveContentControls &&
                    element.Name == W.sdt)
                    return element
                        .Elements(W.sdtContent)
                        .Elements()
                        .Select(e =>
                            RemoveCustomXmlAndContentControlsTransform(e,
                                simplifyMarkupSettings));

                return new XElement(element.Name,
                    element.Attributes(),
                    element.Nodes().Select(n => RemoveCustomXmlAndContentControlsTransform(n, simplifyMarkupSettings)));
            }

            return node;
        }

        private static object RemoveRsidTransform(XNode node)
        {
            var element = node as XElement;
            if (element == null) return node;

            if (element.Name == W.rsid)
                return null;

            return new XElement(element.Name,
                element
                    .Attributes()
                    .Where(a => (a.Name != W.rsid) &&
                                (a.Name != W.rsidDel) &&
                                (a.Name != W.rsidP) &&
                                (a.Name != W.rsidR) &&
                                (a.Name != W.rsidRDefault) &&
                                (a.Name != W.rsidRPr) &&
                                (a.Name != W.rsidSect) &&
                                (a.Name != W.rsidTr)),
                element.Nodes().Select(n => RemoveRsidTransform(n)));
        }

        private static object MergeAdjacentRunsTransform(XNode node)
        {
            var element = node as XElement;
            if (element == null) return node;

            if (element.Name == W.p)
                return WordprocessingMLUtil.CoalesceAdjacentRunsWithIdenticalFormatting(element);

            return new XElement(element.Name,
                element.Attributes(),
                element.Nodes().Select(n => MergeAdjacentRunsTransform(n)));
        }

        private static object RemoveEmptyRunsAndRunPropertiesTransform(
            XNode node)
        {
            var element = node as XElement;
            if (element != null)
            {
                if (((element.Name == W.r) || (element.Name == W.rPr) || (element.Name == W.pPr)) &&
                    !element.Elements().Any())
                    return null;

                return new XElement(element.Name,
                    element.Attributes(),
                    element.Nodes().Select(n => RemoveEmptyRunsAndRunPropertiesTransform(n)));
            }

            return node;
        }

        private static object MergeAdjacentInstrText(
            XNode node)
        {
            var element = node as XElement;
            if (element != null)
            {
                if ((element.Name == W.r) && element.Elements(W.instrText).Any())
                {
                    IEnumerable<IGrouping<bool, XElement>> grouped =
                        element.Elements().GroupAdjacent(e => e.Name == W.instrText);
                    return new XElement(W.r,
                        grouped.Select(g =>
                        {
                            if (g.Key == false)
                                return (object) g;

                            // If .doc files are converted to .docx by the Binary to Open XML Translator,
                            // the w:instrText elements might be empty, in which case newInstrText would
                            // be an empty string.
                            string newInstrText = g.Select(i => (string) i).StringConcatenate();
                            if (string.IsNullOrEmpty(newInstrText))
                                return new XElement(W.instrText);

                            return new XElement(W.instrText,
                                (newInstrText[0] == ' ') || (newInstrText[newInstrText.Length - 1] == ' ')
                                    ? new XAttribute(XNamespace.Xml + "space", "preserve")
                                    : null,
                                newInstrText);
                        }));
                }

                return new XElement(element.Name,
                    element.Attributes(),
                    element.Nodes().Select(n => MergeAdjacentInstrText(n)));
            }

            return node;
        }

        // lastRenderedPageBreak, permEnd, permStart, proofErr, noProof
        // softHyphen:
        // Remove when simplifying.

        // fldSimple, fldData, fldChar, instrText:
        // For hyperlinks, generate same in XHtml.  Other than hyperlinks, do the following:
        // - collapse fldSimple
        // - remove fldSimple, fldData, fldChar, instrText.

        private static object SimplifyMarkupTransform(
            XNode node,
            SimplifyMarkupSettings settings,
            SimplifyMarkupParameters parameters)
        {
            var element = node as XElement;
            if (element == null) return node;

            if (settings.RemovePermissions &&
                ((element.Name == W.permEnd) ||
                 (element.Name == W.permStart)))
                return null;

            if (settings.RemoveProof &&
                ((element.Name == W.proofErr) ||
                 (element.Name == W.noProof)))
                return null;

            if (settings.RemoveSoftHyphens &&
                (element.Name == W.softHyphen))
                return null;

            if (settings.RemoveLastRenderedPageBreak &&
                (element.Name == W.lastRenderedPageBreak))
                return null;

            if (settings.RemoveBookmarks &&
                ((element.Name == W.bookmarkStart) ||
                 (element.Name == W.bookmarkEnd)))
                return null;

            if (settings.RemoveGoBackBookmark &&
                (((element.Name == W.bookmarkStart) && ((int) element.Attribute(W.id) == parameters.GoBackId)) ||
                 ((element.Name == W.bookmarkEnd) && ((int) element.Attribute(W.id) == parameters.GoBackId))))
                return null;

            if (settings.RemoveWebHidden &&
                (element.Name == W.webHidden))
                return null;

            if (settings.ReplaceTabsWithSpaces &&
                (element.Name == W.tab) && 
                (element.Parent != null && element.Parent.Name == W.r))
                return new XElement(W.t, new XAttribute(XNamespace.Xml + "space", "preserve"), " ");

            if (settings.RemoveComments &&
                ((element.Name == W.commentRangeStart) ||
                 (element.Name == W.commentRangeEnd) ||
                 (element.Name == W.commentReference) ||
                 (element.Name == W.annotationRef)))
                return null;

            if (settings.RemoveComments &&
                (element.Name == W.rStyle) &&
                (element.Attribute(W.val).Value == "CommentReference"))
                return null;

            if (settings.RemoveEndAndFootNotes &&
                ((element.Name == W.endnoteReference) ||
                 (element.Name == W.footnoteReference)))
                return null;

            if (settings.RemoveFieldCodes)
            {
                if (element.Name == W.fldSimple)
                    return element.Elements().Select(e => SimplifyMarkupTransform(e, settings, parameters));

                if ((element.Name == W.fldData) ||
                    (element.Name == W.fldChar) ||
                    (element.Name == W.instrText))
                    return null;
            }

            if (settings.RemoveHyperlinks &&
                (element.Name == W.hyperlink))
                return element.Elements();

            return new XElement(element.Name,
                element.Attributes(),
                element.Nodes().Select(n => SimplifyMarkupTransform(n, settings, parameters)));
        }

        private static XDocument Normalize(XDocument source, XmlSchemaSet schema)
        {
            var havePsvi = false;

            // validate, throw errors, add PSVI information
            if (schema != null)
            {
                source.Validate(schema, null, true);
                havePsvi = true;
            }
            return new XDocument(
                source.Declaration,
                source.Nodes().Select(n =>
                {
                    // Remove comments, processing instructions, and text nodes that are
                    // children of XDocument.  Only white space text nodes are allowed as
                    // children of a document, so we can remove all text nodes.
                    if (n is XComment || n is XProcessingInstruction || n is XText)
                        return null;

                    var e = n as XElement;
                    return e != null ? NormalizeElement(e, havePsvi) : n;
                }));
        }

        // TODO: Check whether this can be removed.
        //private static bool DeepEqualsWithNormalization(XDocument doc1, XDocument doc2, XmlSchemaSet schemaSet)
        //{
        //    XDocument d1 = Normalize(doc1, schemaSet);
        //    XDocument d2 = Normalize(doc2, schemaSet);
        //    return XNode.DeepEquals(d1, d2);
        //}

        private static IEnumerable<XAttribute> NormalizeAttributes(XElement element, bool havePsvi)
        {
            return element.Attributes()
                .Where(a => !a.IsNamespaceDeclaration &&
                            (a.Name != Xsi.schemaLocation) &&
                            (a.Name != Xsi.noNamespaceSchemaLocation))
                .OrderBy(a => a.Name.NamespaceName)
                .ThenBy(a => a.Name.LocalName)
                .Select(a =>
                {
                    if (havePsvi)
                    {
                        IXmlSchemaInfo schemaInfo = a.GetSchemaInfo();
                        XmlSchemaType schemaType = schemaInfo != null ? schemaInfo.SchemaType : null;
                        XmlTypeCode? typeCode = schemaType != null ? schemaType.TypeCode : (XmlTypeCode?) null;

                        switch (typeCode)
                        {
                            case XmlTypeCode.Boolean:
                                return new XAttribute(a.Name, (bool) a);
                            case XmlTypeCode.DateTime:
                                return new XAttribute(a.Name, (DateTime) a);
                            case XmlTypeCode.Decimal:
                                return new XAttribute(a.Name, (decimal) a);
                            case XmlTypeCode.Double:
                                return new XAttribute(a.Name, (double) a);
                            case XmlTypeCode.Float:
                                return new XAttribute(a.Name, (float) a);
                            case XmlTypeCode.HexBinary:
                            case XmlTypeCode.Language:
                                return new XAttribute(a.Name,
                                    ((string) a).ToLower());
                        }
                    }

                    return a;
                });
        }

        private static XNode NormalizeNode(XNode node, bool havePsvi)
        {
            // trim comments and processing instructions from normalized tree
            if (node is XComment || node is XProcessingInstruction)
                return null;

            var e = node as XElement;
            if (e != null)
                return NormalizeElement(e, havePsvi);

            // Only thing left is XCData and XText, so clone them
            return node;
        }

        private static XElement NormalizeElement(XElement element, bool havePsvi)
        {
            if (havePsvi)
            {
                IXmlSchemaInfo schemaInfo = element.GetSchemaInfo();
                XmlSchemaType schemaType = schemaInfo != null ? schemaInfo.SchemaType : null;
                XmlTypeCode? typeCode = schemaType != null ? schemaType.TypeCode : (XmlTypeCode?) null;

                switch (typeCode)
                {
                    case XmlTypeCode.Boolean:
                        return new XElement(element.Name,
                            NormalizeAttributes(element, true),
                            (bool) element);
                    case XmlTypeCode.DateTime:
                        return new XElement(element.Name,
                            NormalizeAttributes(element, true),
                            (DateTime) element);
                    case XmlTypeCode.Decimal:
                        return new XElement(element.Name,
                            NormalizeAttributes(element, true),
                            (decimal) element);
                    case XmlTypeCode.Double:
                        return new XElement(element.Name,
                            NormalizeAttributes(element, true),
                            (double) element);
                    case XmlTypeCode.Float:
                        return new XElement(element.Name,
                            NormalizeAttributes(element, true),
                            (float) element);
                    case XmlTypeCode.HexBinary:
                    case XmlTypeCode.Language:
                        return new XElement(element.Name,
                            NormalizeAttributes(element, true),
                            ((string) element).ToLower());
                    default:
                        return new XElement(element.Name,
                            NormalizeAttributes(element, true),
                            element.Nodes().Select(n => NormalizeNode(n, true)));
                }
            }

            return new XElement(element.Name,
                NormalizeAttributes(element, false),
                element.Nodes().Select(n => NormalizeNode(n, false)));
        }

        private static void SimplifyMarkupForPart(OpenXmlPart part, SimplifyMarkupSettings settings)
        {
            var parameters = new SimplifyMarkupParameters();
            if (part.ContentType == "application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml")
            {
                var doc = (WordprocessingDocument) part.OpenXmlPackage;
                if (settings.RemoveGoBackBookmark)
                {
                    XElement goBackBookmark = doc
                        .MainDocumentPart
                        .GetXDocument()
                        .Descendants(W.bookmarkStart)
                        .FirstOrDefault(bm => (string) bm.Attribute(W.name) == "_GoBack");
                    if (goBackBookmark != null)
                        parameters.GoBackId = (int) goBackBookmark.Attribute(W.id);
                }
            }

            XDocument xdoc = part.GetXDocument();
            XElement newRoot = xdoc.Root;

            // Need to do this first to enable simplifying hyperlinks.
            if (settings.RemoveContentControls || settings.RemoveSmartTags)
                newRoot = (XElement) RemoveCustomXmlAndContentControlsTransform(newRoot, settings);

            // This may touch many elements, so needs to be its own transform.
            if (settings.RemoveRsidInfo)
                newRoot = (XElement) RemoveRsidTransform(newRoot);

            var prevNewRoot = new XDocument(newRoot);
            while (true)
            {
                if (settings.RemoveComments ||
                    settings.RemoveEndAndFootNotes ||
                    settings.ReplaceTabsWithSpaces ||
                    settings.RemoveFieldCodes ||
                    settings.RemovePermissions ||
                    settings.RemoveProof ||
                    settings.RemoveBookmarks ||
                    settings.RemoveWebHidden ||
                    settings.RemoveGoBackBookmark ||
                    settings.RemoveHyperlinks)
                    newRoot = (XElement) SimplifyMarkupTransform(newRoot, settings, parameters);

                // Remove runs and run properties that have become empty due to previous transforms.
                newRoot = (XElement) RemoveEmptyRunsAndRunPropertiesTransform(newRoot);

                // Merge adjacent runs that have identical run properties.
                newRoot = (XElement) MergeAdjacentRunsTransform(newRoot);

                // Merge adjacent instrText elements.
                newRoot = (XElement) MergeAdjacentInstrText(newRoot);

                // Separate run children into separate runs
                newRoot = (XElement) SeparateRunChildrenIntoSeparateRuns(newRoot);

                if (XNode.DeepEquals(prevNewRoot.Root, newRoot))
                    break;

                prevNewRoot = new XDocument(newRoot);
            }

            if (settings.NormalizeXml)
            {
                XAttribute[] nsAttrs =
                {
                    new XAttribute(XNamespace.Xmlns + "wpc", WPC.wpc),
                    new XAttribute(XNamespace.Xmlns + "mc", MC.mc),
                    new XAttribute(XNamespace.Xmlns + "o", O.o),
                    new XAttribute(XNamespace.Xmlns + "r", R.r),
                    new XAttribute(XNamespace.Xmlns + "m", M.m),
                    new XAttribute(XNamespace.Xmlns + "v", VML.vml),
                    new XAttribute(XNamespace.Xmlns + "wp14", WP14.wp14),
                    new XAttribute(XNamespace.Xmlns + "wp", WP.wp),
                    new XAttribute(XNamespace.Xmlns + "w10", W10.w10),
                    new XAttribute(XNamespace.Xmlns + "w", W.w),
                    new XAttribute(XNamespace.Xmlns + "w14", W14.w14),
                    new XAttribute(XNamespace.Xmlns + "w15", W15.w15),
                    new XAttribute(XNamespace.Xmlns + "w16se", W16SE.w16se),
                    new XAttribute(XNamespace.Xmlns + "wpg", WPG.wpg),
                    new XAttribute(XNamespace.Xmlns + "wpi", WPI.wpi),
                    new XAttribute(XNamespace.Xmlns + "wne", WNE.wne),
                    new XAttribute(XNamespace.Xmlns + "wps", WPS.wps),
                    new XAttribute(MC.Ignorable, "w14 wp14 w15 w16se"),
                };

                XDocument newXDoc = Normalize(new XDocument(newRoot), null);
                newRoot = newXDoc.Root;
                if (newRoot != null)
                    foreach (XAttribute nsAttr in nsAttrs)
                        if (newRoot.Attribute(nsAttr.Name) == null)
                            newRoot.Add(nsAttr);

                part.PutXDocument(newXDoc);
            }
            else
            {
                part.PutXDocument(new XDocument(newRoot));
            }
        }

        private static object SeparateRunChildrenIntoSeparateRuns(XNode node)
        {
            var element = node as XElement;
            if (element == null) return node;

            if (element.Name == W.r)
            {
                IEnumerable<XElement> runChildren = element.Elements().Where(e => e.Name != W.rPr);
                XElement rPr = element.Element(W.rPr);
                return runChildren.Select(rc => new XElement(W.r, rPr, rc));
            }

            return new XElement(element.Name,
                element.Attributes(),
                element.Nodes().Select(n => SeparateRunChildrenIntoSeparateRuns(n)));
        }

        private static object SingleCharacterRunTransform(XNode node)
        {
            var element = node as XElement;
            if (element == null) return node;

            if (element.Name == W.r)
                return element.Elements()
                    .Where(e => e.Name != W.rPr)
                    .GroupAdjacent(sr => sr.Name == W.t)
                    .Select(g =>
                    {
                        if (g.Key)
                        {
                            string s = g.Select(t => (string) t).StringConcatenate();
                            return s.Select(c =>
                                new XElement(W.r,
                                    element.Elements(W.rPr),
                                    new XElement(W.t,
                                        c == ' ' ? new XAttribute(XNamespace.Xml + "space", "preserve") : null,
                                        c)));
                        }

                        return g.Select(sr =>
                            new XElement(W.r,
                                element.Elements(W.rPr),
                                new XElement(sr.Name,
                                    sr.Attributes(),
                                    sr.Nodes().Select(n => SingleCharacterRunTransform(n)))));
                    });

            return new XElement(element.Name,
                element.Attributes(),
                element.Nodes().Select(n => SingleCharacterRunTransform(n)));
        }

        private static class Xsi
        {
            private static readonly XNamespace xsi = "http://www.w3.org/2001/XMLSchema-instance";

            public static readonly XName schemaLocation = xsi + "schemaLocation";
            public static readonly XName noNamespaceSchemaLocation = xsi + "noNamespaceSchemaLocation";
        }

        public class InternalException : Exception
        {
            public InternalException(string message) : base(message)
            {
            }
        }

        public class InvalidSettingsException : Exception
        {
            public InvalidSettingsException(string message) : base(message)
            {
            }
        }

        private class SimplifyMarkupParameters
        {
            public int? GoBackId { get; set; }
        }
    }
}