#if DEBUG
#define DEBUGOCR
#endif
using System;
using System.Collections.Generic;
using System.IO;
using System.Text.RegularExpressions;
using System.Xml;
using iTextSharp.text.pdf;
using PDFPatcher.Common;
using PDFPatcher.Model;
using PDFPatcher.Processor.Imaging;

namespace PDFPatcher.Processor
{
	sealed class OcrProcessor
	{
		internal sealed class Result
		{
			public ImageDisposition Image { get; }
			public List<TextLine> Texts { get; }
			public Result(ImageDisposition image) {
				Image = image;
				Texts = new List<TextLine>();
			}
		}

		const int OpenWorkload = 1;
		const string __punctuations = @"·．“”，,\.－""～∼。:：\p{P}";
		static readonly AutoBookmarkOptions __MergeOptions = new AutoBookmarkOptions { MergeAdjacentTitles = true, MergeDifferentSizeTitles = true };
		static readonly Regex __ContentPunctuationExpression = new Regex(@"[" + __punctuations + @"][" + __punctuations + @"0一\s]+[" + __punctuations + @"]\s*", RegexOptions.Compiled);
		static readonly Regex __ContinuousWhiteSpaceExpression = new Regex(@"[ 　]{3,}", RegexOptions.Compiled);
		static readonly Regex __WhiteSpaceBetweenChineseCharacters = new Regex(@"([\u4E00-\u9FFF\u3400-\u4DBF])[ 　]+(?=[\u4E00-\u9FFF\u3400-\u4DBF])", RegexOptions.Compiled);

		private readonly ModiOcr _Ocr;
		private readonly float _OcrQuantitativeFactor;
		private readonly PdfReader _reader;
		private readonly ImageExtractor _ocrImageExp;
		private readonly OcrOptions _options;
		private IResultWriter _resultWriter;

		public OcrProcessor(PdfReader reader, OcrOptions options) : this(options) {
			var expOptions = new ImageExtracterOptions() {
				OutputPath = Path.GetTempPath(),
				FileMask = "\"ocr-" + DateTime.Now.ToString("yyMMddHHmmss") + "-\"0000",
				MergeImages = true,
				MergeJpgToPng = true,
				MinHeight = 100,
				MinWidth = 100
			};
			CleanUpTempFiles(expOptions.OutputPath);
			_reader = reader;
			_ocrImageExp = new ImageExtractor(expOptions) {
				PrintImageLocation = false
			};
		}

		private OcrProcessor(OcrOptions options) {
			_Ocr = new ModiOcr {
				LangID = options.OcrLangID,
				StretchPage = options.StretchPage,
				OrientPage = options.OrientPage,
				WritingDirection = options.WritingDirection
			};
			_OcrQuantitativeFactor = options.QuantitativeFactor;
			_options = options;
		}

		private static void CleanUpTempFiles(string folderPath) {
			var tf = Directory.GetFiles(folderPath, "ocr-*.tif");
			foreach (var file in tf) {
				try {
					File.Delete(file);
				}
				catch (Exception) {
				}
			}
		}

		internal int EstimateWorkload() {
			var n = _reader.NumberOfPages;
			var load = 0;
			load += OpenWorkload;
			var t = PageRangeCollection.Parse(_options.PageRanges, 1, n, true).TotalPages;
			load += t > 0 ? t : n;
			return load;
		}

		internal void SetWriter(XmlWriter writer) {
			_resultWriter = new XmlResultWriter(writer);
		}
		internal void SetWriter(TextWriter writer) {
			_resultWriter = new TextResultWriter(writer);
		}

		internal void PerformOcr() {
			Tracker.IncrementProgress(OpenWorkload);
			var ranges = PageRangeCollection.Parse(_options.PageRanges, 1, _reader.NumberOfPages, true);
			__MergeOptions.DetectColumns = _options.DetectColumns;
			__MergeOptions.WritingDirection = _options.WritingDirection;
			TextLine.DefaultDirection = _options.WritingDirection;
			if (FileHelper.IsPathValid(_options.SaveOcredImagePath)) {
				File.Delete(_options.SaveOcredImagePath);
			}
			var el = new List<int>();
			foreach (PageRange r in ranges) {
				for (int i = r.StartValue; i <= r.EndValue; i++) {
					Tracker.TraceMessage("正在识别第 " + i + " 页。");
					var or = OcrPage(i, el);
					if (or.Count > 0) {
						_resultWriter?.BeginWritePage(i);

						foreach (var result in or) {
							_resultWriter?.BeginWriteImage(result.Image);
							if (_options.OutputOriginalOcrResult) {
								if (_resultWriter != null) {
									foreach (var item in result.Texts) {
										_resultWriter.WriteText(item, null);
									}
								}
							}
							else {
								WriteOcrResult(i, result);
							}
							_resultWriter?.EndWriteImage();
						}
						_resultWriter?.EndWritePage();
					}
					Tracker.IncrementProgress(1);
				}
			}
			if (el.Count > 0) {
				Tracker.TraceMessage(Tracker.Category.Alert, String.Concat("有 ", el.Count, " 页在识别过程中出现错误，页码为：", String.Join(", ", el)));
			}
		}

		private void WriteOcrResult(int i, Result result) {
			SortRecognizedText(result.Texts, _options);
			var pr = _reader.GetPageNRelease(i).GetPageVisibleRectangle();
			var tl = _options.WritingDirection != WritingDirection.Unknown
				? AutoBookmarkCreator.MergeTextInfoList(pr, result.Texts.ConvertAll((l) => GetMergedTextInfo(result.Image, l)), __MergeOptions) // 按照书写方向重组识别文本
				: result.Texts;
			foreach (var item in tl) {
				var t = item.Text;
				var ir = item.Region;

				t = CleanUpText(t, _options);
				if (_options.PrintOcrResult) {
#if DEBUG
					Tracker.TraceMessage(String.Concat(item.Direction.ToString()[0], ir.Top.ToString(" 0000"), ',', ir.Left.ToString("0000"), "(", ir.Width.ToString("0000"), ',', ir.Height.ToString("0000"), ")\t", t));
#else
					Tracker.TraceMessage (t);
#endif
				}

				_resultWriter?.WriteText(item, t);
			}
		}

		/// <summary>
		/// 根据识别选项优化输出结果。
		/// </summary>
		/// <param name="text">文本内容。</param>
		/// <param name="options">识别选项。</param>
		/// <returns>优化后的文本。</returns>
		internal static string CleanUpText(string text, OcrOptions options) {
			if (options.DetectContentPunctuations) {
				text = __ContentPunctuationExpression.Replace(text, " .... ");
			}
			if (options.CompressWhiteSpaces) {
				text = __ContinuousWhiteSpaceExpression.Replace(text, "  ");
			}
			if (options.RemoveWhiteSpacesBetweenChineseCharacters) {
				text = __WhiteSpaceBetweenChineseCharacters.Replace(text, "$1");
			}
			return text;
		}

		private IList<Result> OcrPage(int i, List<int> errorList) {
#if DEBUGOCR
			Tracker.TraceMessage("导出第 " + i + " 页的图片。");
#endif
			_ocrImageExp.ExtractPageImages(_reader, i);
#if DEBUGOCR
			Tracker.TraceMessage("完成导出第 " + i + " 页的图片。");
#endif
			var or = new List<Result>();
			try {
				foreach (var item in _ocrImageExp.PosList) {
					var r = new Result(item);
					OcrPage(r);
					or.Add(r);
					r = null;
				}
			}
			catch (System.Runtime.InteropServices.COMException ex) {
				string err = null;
				switch (ex.ErrorCode) {
					case -959967087:
						err = "页面的图片不包含可识别的文本。";
						goto default;
					default:
						Tracker.TraceMessage(Tracker.Category.Error, "在执行第 " + i + " 页的光学字符识别时出错：");
						if (err != null) {
							Tracker.TraceMessage(err);
						}
						else {
							Tracker.TraceMessage("错误编号：" + ex.ErrorCode);
							Tracker.TraceMessage(ex);
							errorList.Add(i);
						}
						break;
				}
			}
			catch (Exception ex) {
				Tracker.TraceMessage(Tracker.Category.Error, "在执行第 " + i + " 页的光学字符识别时出错：");
				Tracker.TraceMessage(ex);
				errorList.Add(i);
			}
			finally {
				foreach (var item in _ocrImageExp.InfoList) {
					if (String.IsNullOrEmpty(item.FileName)) {
						continue;
					}
					try {
						File.Delete(item.FileName);
					}
					catch (Exception ex) {
						Tracker.TraceMessage(Tracker.Category.Error, ex.Message);
						Tracker.TraceMessage(Tracker.Category.Error, "无法删除识别过程中产生的临时文件：" + item.FileName);
					}
				}
			}
			return or;
		}

		private void OcrPage(Result result) {
			var image = result.Image;
			var p = image.Image.FileName;
			if (String.IsNullOrEmpty(p)) {
				return;
			}
#if DEBUGOCR
			Tracker.TraceMessage("识别图片：" + p);
#endif
#if DEBUG
			Tracker.TraceMessage(p);
#endif
			result.Texts.Clear();
			OcrImageFile(result.Texts, p);
			#region Legacy code
			//            var ll = new List<TextLine> ();
			//            // 同行合并宽度最小值
			//            var cw = image.Image.Width / 4;

			//            // 遍历识别所得的各 TextInfo，使用最小距离聚类方法将其聚类为行
			//            foreach (var item in or) {
			//                var ir = item.Region;
			//                DistanceInfo cd = null; // TextInfo 到 TextLine 的距离
			//                DistanceInfo md = new DistanceInfo (DistanceInfo.Placement.Unknown, float.MaxValue); // 最小距离
			//                TextLine ml = null; // 最小距离的 TextLine

			//if (item.Text == "哉") {
			//    var lxx = 1;
			//}
			//                // 求最小距离的 TextLine
			//                foreach (var li in ll) {
			//                    cd = li.GetDistance (ir);
			//                    if ((cd.Location == DistanceInfo.Placement.Overlapping // 当前项与文本行交叠
			//                            && (md.Location != DistanceInfo.Placement.Overlapping // 最小距离不是交叠
			//                                || cd.Distance < md.Distance) // 当前项与文本行的交叠中心距离小于最小距离
			//                            )
			//                        || ((md.Location == DistanceInfo.Placement.Unknown // 未知最小距离
			//                            || (cd.Location != DistanceInfo.Placement.Overlapping
			//                                && md.Location != DistanceInfo.Placement.Overlapping
			//                                && cd.Distance < md.Distance) // 当前项与文本行的距离小于最小距离
			//                            )
			//                            && (((cd.Location == DistanceInfo.Placement.Left || cd.Location == DistanceInfo.Placement.Right) // 相对位置为水平
			//                                    && li.Direction != TextLine.WritingDirection.Vertical // 文本行方向不为纵向
			//                                    )
			//                                || ((cd.Location == DistanceInfo.Placement.Up || cd.Location == DistanceInfo.Placement.Down) // 相对位置为垂直
			//                                    && li.Direction != TextLine.WritingDirection.Horizontal // 文本行方向不为横向
			//                                    )
			//                                )
			//                            && cd.Distance < cw
			//                        )
			//                        ) {
			//                        md = cd;
			//                        ml = li;
			//                    }
			//                }

			//                if (ml != null) {
			//                    // 若存在最小距离的 TextLine 且可合并，则将 item 归入 TextLine
			//                    if (md.Location == DistanceInfo.Placement.Overlapping) {
			//                        // 检查是否存在交叠重复的文本
			//                        foreach (var t in ml.Texts) {
			//                            if (t.Region.IntersectWith (item.Region) // item 与 TextLine 中某项交叠
			//                                && (t.Text.Contains (item.Text) || item.Text.Contains (t.Text) // 交叠的项文本和 item 的文本相同
			//                                )
			//                                ) {
			//                                goto Next; // 忽略此项目
			//                            }
			//                        }
			//                    }
			//                    ml.AddText (item);
			//                }
			//                else {
			//                    // 否则，用 item 创建新的 TextLine
			//                    ll.Add (new TextLine (item));
			//                }
			//            Next:
			//                continue;
			//            }

			//if (or.Count > 0) {
			//    float size = 0, size2 = 0, avgSize, maxSize = 0;
			//    float top = or[0].Region.Top, bottom = or[0].Region.Bottom, left = or[0].Region.Left, right = 0;
			//    var sb = new System.Text.StringBuilder ();
			//    int letterCount = 0;
			//    var rr = new List<TextInfo> ();
			//    Bound r;
			//    var end = or.Count - 1;
			//    for (var i = 0; i <= end; i++) {
			//        var item = or[i];
			//        r = item.Region;
			//        avgSize = letterCount > 0 ? size / letterCount : maxSize;
			//    AddLine:
			//        if (r.Top > bottom + 0.2f * (avgSize) || i > end) { // 新行
			//            size = image.YScale * avgSize;
			//            if (_OcrQuatitiveFactor > 0) {
			//                var a = Math.IEEERemainder (size, _OcrQuatitiveFactor);
			//                var b = Math.IEEERemainder (size + _OcrQuatitiveFactor, _OcrQuatitiveFactor);
			//                if (a < b) {
			//                    size -= (float)a;
			//                }
			//                else {
			//                    size += _OcrQuatitiveFactor - (float)b;
			//                }
			//            }
			//            if (size >= _fontSizeThreshold) {
			//                var ni = new TextInfo ()
			//                {
			//                    Text = sb.ToString (),
			//                    Size = size,
			//                    Region = new Bound (
			//                        image.X + image.XScale * left,
			//                        image.Y + image.YScale * (image.Image.Height - bottom),
			//                        image.X + image.XScale * right,
			//                        image.Y + image.YScale * (image.Image.Height - top)),
			//                    Font = -1
			//                };
			//                rr.Add (ni);
			//            }
			//            maxSize = size = size2 = 0;
			//            left = r.Left;
			//            right = r.Right;
			//            top = r.Top;
			//            bottom = r.Bottom;
			//            sb.Length = 0;
			//            letterCount = 0;
			//            if (i > end) {
			//                break;
			//            }
			//        }
			//        if (Char.IsLetter (item.Text[0])) {
			//            size += item.Size;
			//            size2 += item.Size * item.Size;
			//            letterCount++;
			//        }
			//        if (item.Size > maxSize) {
			//            maxSize = item.Size;
			//        }
			//        if (r.Top < top) {
			//            top = r.Top;
			//        }
			//        if (r.Bottom > bottom) {
			//            bottom = r.Bottom;
			//        }
			//        if (r.Right > right) {
			//            right = r.Right;
			//        }
			//        sb.Append (item.Text);
			//        if (i == end) {
			//            i++;
			//            goto AddLine;
			//        }
			//    }
			//    this._TextList.AddRange (rr);
			//}
			#endregion
		}

		private void OcrImageFile(List<TextLine> result, string p) {
			var sp = _options.SaveOcredImagePath;
			if (FileHelper.HasExtension(p, Constants.FileExtensions.Tif) == false) {
				using (var fi = new FreeImageAPI.FreeImageBitmap(p)) {
#if !DEBUG
					var t = Path.GetDirectoryName (p) + "\\ocr-" + new Random ().Next ().ToText () +".tif";
#else
					var t = "m:\\ocr.tif";
#endif
					if (_options.PreserveColor) {
						fi.Save(t, FreeImageAPI.FREE_IMAGE_FORMAT.FIF_TIFF);
					}
					else {
						using (var ti = fi.GetColorConvertedInstance(FreeImageAPI.FREE_IMAGE_COLOR_DEPTH.FICD_01_BPP_THRESHOLD)) {
							ti.Save(t, FreeImageAPI.FREE_IMAGE_FORMAT.FIF_TIFF);
						}
					}
					_Ocr.Ocr(t, sp, result);
#if !DEBUG
					try {
						File.Delete (t);
					}
					catch (Exception) {
						Tracker.TraceMessage (Tracker.Category.Notice, "无法删除临时文件：" + t);
					}
#endif
				}
			}
			else {
				_Ocr.Ocr(p, sp, result);
			}
#if DEBUGOCR
			Tracker.TraceMessage("完成识别图片：" + p);
#endif
			return;
		}

		/// <summary>
		/// 调用图像处理引擎识别位图。如图片中的文本量太少，将无法识别，并会抛出异常。
		/// </summary>
		/// <param name="bmp">需要识别的图片。</param>
		/// <param name="options">识别选项。</param>
		/// <exception cref="System.Runtime.InteropServices.COMException">在识别时发生的错误。</exception>
		/// <returns>识别后的文本。</returns>
		internal static List<TextLine> OcrBitmap(System.Drawing.Bitmap bmp, OcrOptions options) {
			const int minSize = 500;
			var ocr = new OcrProcessor(options);
			var r = new List<TextLine>();
			string p = null;
			using (var fi = new FreeImageAPI.FreeImageBitmap(bmp)) {
				if (fi.Width < minSize || fi.Height < minSize) {
					fi.EnlargeCanvas<FreeImageAPI.RGBQUAD>(0, 0, fi.Width < minSize ? minSize : fi.Width, fi.Height < minSize ? minSize : fi.Height, new FreeImageAPI.RGBQUAD(fi.GetPixel(0, 0)));
				}
				p = FileHelper.CombinePath(Path.GetTempPath(), new Random().Next(Int32.MaxValue).ToText() + Constants.FileExtensions.Tif);
				fi.Save(p, FreeImageAPI.FREE_IMAGE_FORMAT.FIF_TIFF);
			}
			ocr._Ocr.Ocr(p, null, r);
			File.Delete(p);
			return r;
		}

		private static TextInfo GetMergedTextInfo(ImageDisposition image, TextLine item) {
			var ti = new TextInfo {
				Font = null,
				Region = item.Region,
				Text = item.Text,
				Size = (float)Math.Round(item.Direction == WritingDirection.Vertical ? item.Region.Width/* * image.XScale*/ : item.Region.Height/* * image.YScale*/),
				LetterWidth = item.GetAverageCharSize()
			};
			//if (item.Texts.Count > 0) {
			//    float aw = 0;
			//    foreach (var t in item.Texts) {
			//        aw += t.LetterWidth;
			//    }
			//    aw /= item.Texts.Count;
			//    ti.LetterWidth = aw;
			//}
			return ti;
		}

		private static void SortRecognizedText(List<TextLine> list, OcrOptions ocrOptions) {
			if (ocrOptions.WritingDirection == WritingDirection.Horizontal) {
				list.Sort((a, b) => {
					var ra = a.Region;
					var rb = b.Region;
					if (ra.Bottom > rb.Top) {
						return 1;
					}
					if (ra.Top < rb.Bottom) {
						return -1;
					}
					if (ra.IsAlignedWith(rb, WritingDirection.Horizontal)) {
						return ra.Center < rb.Center ? -1 : 1;
					}
					return ra.Middle < rb.Middle ? -1 : 1;
				});
			}
			else if (ocrOptions.WritingDirection == WritingDirection.Vertical) {
				list.Sort((a, b) => {
					var ra = a.Region;
					var rb = b.Region;
					if (ra.Left > rb.Right) {
						return -1;
					}
					if (ra.Right < rb.Left) {
						return 1;
					}
					if (ra.IsAlignedWith(rb, WritingDirection.Vertical)) {
						return ra.Middle > rb.Middle ? -1 : 1;
					}
					return ra.Center > rb.Center ? -1 : 1;
				});
			}
		}

		interface IResultWriter
		{
			void BeginWritePage(int i);
			void BeginWriteImage(ImageDisposition image);
			void WriteText(TextLine text, string optimizedText);
			void EndWriteImage();
			void EndWritePage();
		}

		sealed class XmlResultWriter : IResultWriter
		{
			readonly XmlWriter _writer;
			public XmlResultWriter(XmlWriter writer) {
				_writer = writer;
			}

			#region IResultWriter 成员

			public void BeginWritePage(int i) {
				_writer.WriteStartElement(Constants.Ocr.Result);
				_writer.WriteAttributeString(Constants.Content.PageNumber, ValueHelper.ToText(i));
			}

			public void WriteText(TextLine text, string optimizedText) {
				if (optimizedText != null) {
					WriteTextItem(optimizedText, text.Region, text.Direction);
					return;
				}
				_writer.WriteComment(text.Text);
				foreach (var item in text.Texts) {
					WriteTextItem(item.Text, item.Region, WritingDirection.Unknown);
				}
			}

			private void WriteTextItem(string text, Bound ir, WritingDirection direction) {
				_writer.WriteStartElement(Constants.Ocr.Content);
				_writer.WriteAttributeString(Constants.Ocr.Text, text);
				switch (direction) {
					case WritingDirection.Horizontal:
						_writer.WriteAttributeString(Constants.Coordinates.Direction, Constants.Coordinates.Horizontal);
						break;
					case WritingDirection.Vertical:
						_writer.WriteAttributeString(Constants.Coordinates.Direction, Constants.Coordinates.Vertical);
						break;
				}
				_writer.WriteAttributeString(Constants.Coordinates.Top, ValueHelper.ToText(Math.Round(ir.Top)));
				_writer.WriteAttributeString(Constants.Coordinates.Left, ValueHelper.ToText(Math.Round(ir.Left)));
				_writer.WriteAttributeString(Constants.Coordinates.Bottom, ValueHelper.ToText(Math.Round(ir.Bottom)));
				_writer.WriteAttributeString(Constants.Coordinates.Right, ValueHelper.ToText(Math.Round(ir.Right)));
				_writer.WriteEndElement();
			}

			public void EndWritePage() {
				_writer.WriteEndElement();
			}

			public void BeginWriteImage(ImageDisposition image) {
				_writer.WriteStartElement(Constants.Ocr.Image);
				_writer.WriteAttributeString(Constants.Coordinates.Width, ValueHelper.ToText(image.Image.Width));
				_writer.WriteAttributeString(Constants.Coordinates.Height, ValueHelper.ToText(image.Image.Height));
				_writer.WriteAttributeString(Constants.Content.OperandNames.Matrix, PdfHelper.MatrixToString(image.Ctm));
			}

			public void EndWriteImage() {
				_writer.WriteEndElement();
			}
			#endregion
		}

		sealed class TextResultWriter : IResultWriter
		{
			readonly TextWriter _writer;
			public TextResultWriter(TextWriter writer) {
				_writer = writer;
			}

			#region IResultWriter 成员

			public void BeginWritePage(int i) {
				_writer.WriteLine("#识别页码=" + i);
			}

			public void WriteText(TextLine text, string optimizedText) {
				_writer.WriteLine(optimizedText ?? text.Text);
			}

			public void EndWritePage() {
				_writer.WriteLine();
			}

			public void BeginWriteImage(ImageDisposition image) {
				_writer.WriteLine("#识别图片=" + PdfHelper.MatrixToString(image.Ctm));
			}

			public void EndWriteImage() { }
			#endregion
		}
	}
}