PdfPig/src/UglyToad.PdfPig/Graphics/InlineImageBuilder.cs

namespace UglyToad.PdfPig.Graphics
{
    using System;
    using System.Collections;
    using System.Collections.Generic;
    using System.Linq;
    using System.Xml.Linq;
    using Content;
    using Core;
    using Filters;
    using PdfPig.Core;
    using Tokenization.Scanner;
    using Tokens;
    using UglyToad.PdfPig.Graphics.Colors;
    using UglyToad.PdfPig.XObjects;

    /// <summary>
    /// Inline Image Builder.
    /// </summary>
    public sealed class InlineImageBuilder
    {
        /// <summary>
        /// Inline image properties.
        /// </summary>
        public IReadOnlyDictionary<NameToken, IToken>? Properties { get; internal set; }

        /// <summary>
        /// Inline image bytes.
        /// </summary>
        public ReadOnlyMemory<byte> Bytes { get; internal set; }

        internal InlineImage CreateInlineImage(
            in TransformationMatrix transformationMatrix,
            ILookupFilterProvider filterProvider,
            IPdfTokenScanner tokenScanner,
            RenderingIntent defaultRenderingIntent,
            IResourceStore resourceStore)
        {
            if (Properties is null)
            {
                throw new InvalidOperationException($"Inline image builder not completely defined before calling {nameof(CreateInlineImage)}.");
            }

            var bounds = transformationMatrix.Transform(new PdfRectangle(new PdfPoint(1, 1),
                new PdfPoint(0, 0)));

            var width = GetByKeys<NumericToken>(NameToken.Width, NameToken.W, true).Int;

            var height = GetByKeys<NumericToken>(NameToken.Height, NameToken.H, true).Int;

            var maskToken = GetByKeys<BooleanToken>(NameToken.ImageMask, NameToken.Im, false);

            var isMask = maskToken?.Data == true;

            var bitsPerComponent = GetByKeys<NumericToken>(NameToken.BitsPerComponent, NameToken.Bpc, !isMask)?.Int ?? 1;
            NameToken? colorSpaceName = null;

            var imgDic = new DictionaryToken(Properties ?? new Dictionary<NameToken, IToken>());

            XObjectImage? softMaskImage = null;
            if (imgDic.TryGet(NameToken.Smask, tokenScanner, out StreamToken? sMaskToken))
            {
                if (!sMaskToken.StreamDictionary.TryGet(NameToken.Subtype, out NameToken softMaskSubType) || !softMaskSubType.Equals(NameToken.Image))
                {
                    throw new Exception("The SMask dictionary does not contain a 'Subtype' entry, or its value is not 'Image'.");
                }

                if (!sMaskToken.StreamDictionary.TryGet(NameToken.ColorSpace, out NameToken softMaskColorSpace) || !softMaskColorSpace.Equals(NameToken.Devicegray))
                {
                    throw new Exception("The SMask dictionary does not contain a 'ColorSpace' entry, or its value is not 'Devicegray'.");
                }

                if (sMaskToken.StreamDictionary.ContainsKey(NameToken.Mask) || sMaskToken.StreamDictionary.ContainsKey(NameToken.Smask))
                {
                    throw new Exception("The SMask dictionary contains a 'Mask' or 'Smask' entry.");
                }

                XObjectContentRecord softMaskImageRecord = new XObjectContentRecord(XObjectType.Image, sMaskToken, TransformationMatrix.Identity,
                    defaultRenderingIntent, DeviceGrayColorSpaceDetails.Instance);

                softMaskImage = XObjectFactory.ReadImage(softMaskImageRecord, tokenScanner, filterProvider, resourceStore);
            }

            if (!isMask)
            {
                colorSpaceName = GetByKeys<NameToken>(NameToken.ColorSpace, NameToken.Cs, false);

                if (colorSpaceName is null)
                {
                    var colorSpaceArray = GetByKeys<ArrayToken>(NameToken.ColorSpace, NameToken.Cs, true);

                    if (colorSpaceArray.Length == 0)
                    {
                        throw new PdfDocumentFormatException("Empty ColorSpace array defined for inline image.");
                    }

                    if (!(colorSpaceArray.Data[0] is NameToken firstColorSpaceName))
                    {
                        throw new PdfDocumentFormatException($"Invalid ColorSpace array defined for inline image: {colorSpaceArray}.");
                    }

                    colorSpaceName = firstColorSpaceName;
                }
            }

            var details = resourceStore.GetColorSpaceDetails(colorSpaceName, imgDic);

            var renderingIntent = GetByKeys<NameToken>(NameToken.Intent, null, false)?.Data?.ToRenderingIntent() ?? defaultRenderingIntent;

            var filterNames = new List<NameToken>();

            var filterName = GetByKeys<NameToken>(NameToken.Filter, NameToken.F, false);

            if (filterName is null)
            {
                var filterArray = GetByKeys<ArrayToken>(NameToken.Filter, NameToken.F, false);

                if (filterArray != null)
                {
                    filterNames.AddRange(filterArray.Data.OfType<NameToken>());
                }
            }
            else
            {
                filterNames.Add(filterName);
            }

            var decodeRaw = GetByKeys<ArrayToken>(NameToken.Decode, NameToken.D, false) ?? new ArrayToken(Array.Empty<IToken>());

            var decode = decodeRaw.Data.OfType<NumericToken>().Select(x => x.Double).ToArray();

            var interpolate = GetByKeys<BooleanToken>(NameToken.Interpolate, NameToken.I, false)?.Data ?? false;

            return new InlineImage(bounds, width, height, bitsPerComponent,
                isMask, renderingIntent, interpolate, decode, Bytes,
                filterProvider, filterNames, imgDic, details, softMaskImage);
        }

#nullable disable

        // ReSharper disable once ParameterOnlyUsedForPreconditionCheck.Local
        private T GetByKeys<T>(NameToken name1, NameToken name2, bool required)
            where T : class, IToken
        {
            if (Properties.TryGetValue(name1, out var val) && val is T result)
            {
                return result;
            }

            if (name2 != null)
            {
                if (Properties.TryGetValue(name2, out val) && val is T result2)
                {
                    return result2;
                }
            }

            if (required)
            {
                throw new PdfDocumentFormatException($"Inline image dictionary missing required entry {name1}/{name2}.");
            }

            return null;
        }
    }
}