using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
using Autodesk.AutoCAD.DatabaseServices;
using CadParamPluging.Common;

namespace CadParamPluging.Cad
{
    public sealed class TemplateAnnotationExtractionResult
    {
        public DropdownOptions Options { get; set; }
        public TemplateAnnotationExtractionSummary Summary { get; set; }
    }

    public sealed class TemplateAnnotationExtractionSummary
    {
        public int LayoutCountScanned { get; set; }
        public int EntityCountScanned { get; set; }
        public int TextObjectCountScanned { get; set; }
        public int MatchedLineCount { get; set; }
    }

    public static class TemplateAnnotationOptionsExtractor
    {
        private static readonly Regex FieldRegex = new Regex(
            @"^\s*(交付状态|工艺方法|结构特征)\s*[:：]\s*(.+?)\s*$",
            RegexOptions.Compiled);

        private static readonly Regex MTextFormatRegex = new Regex(@"\\[A-Za-z]+[^;]*;", RegexOptions.Compiled);

        public static TemplateAnnotationExtractionResult Extract(string templatePath)
        {
            if (string.IsNullOrWhiteSpace(templatePath))
            {
                throw new ArgumentNullException(nameof(templatePath));
            }

            var options = new DropdownOptions();
            var summary = new TemplateAnnotationExtractionSummary();

            using (var db = new Database(false, true))
            {
                ReadTemplateDatabase(db, templatePath);
                db.CloseInput(true);

                using (var tr = db.TransactionManager.StartTransaction())
                {
                    var layoutDict = (DBDictionary)tr.GetObject(db.LayoutDictionaryId, OpenMode.ForRead);
                    foreach (DBDictionaryEntry entry in layoutDict)
                    {
                        var layout = (Layout)tr.GetObject(entry.Value, OpenMode.ForRead);
                        summary.LayoutCountScanned++;

                        var btr = (BlockTableRecord)tr.GetObject(layout.BlockTableRecordId, OpenMode.ForRead);
                        foreach (ObjectId id in btr)
                        {
                            summary.EntityCountScanned++;

                            var obj = tr.GetObject(id, OpenMode.ForRead);
                            if (obj is Entity ent)
                            {
                                foreach (var line in ExtractLinesFromEntity(ent, tr, summary))
                                {
                                    TryParseLine(line, options, summary);
                                }
                            }
                        }
                    }

                    tr.Commit();
                }
            }

            options.Normalize();

            return new TemplateAnnotationExtractionResult
            {
                Options = options,
                Summary = summary
            };
        }

        private static void ReadTemplateDatabase(Database db, string templatePath)
        {
            // AutoCAD .NET 不同版本 ReadDwgFile 的重载参数略有差异，这里优先使用 FileShare 以允许文件被其它进程占用。
            try
            {
                db.ReadDwgFile(templatePath, FileShare.ReadWrite, true, string.Empty);
            }
            catch (MissingMethodException)
            {
                db.ReadDwgFile(templatePath, FileOpenMode.OpenForReadAndAllShare, true, string.Empty);
            }
        }

        private static IEnumerable<string> ExtractLinesFromEntity(Entity ent, Transaction tr, TemplateAnnotationExtractionSummary summary)
        {
            if (ent is DBText text)
            {
                summary.TextObjectCountScanned++;
                return SplitLines(text.TextString);
            }

            if (ent is MText mt)
            {
                summary.TextObjectCountScanned++;
                var plain = SimplifyMText(mt.Contents);
                return SplitLines(plain);
            }

            if (ent is BlockReference br)
            {
                var lines = new List<string>();
                foreach (ObjectId attId in br.AttributeCollection)
                {
                    var att = tr.GetObject(attId, OpenMode.ForRead) as AttributeReference;
                    if (att == null)
                    {
                        continue;
                    }

                    summary.TextObjectCountScanned++;
                    lines.AddRange(SplitLines(att.TextString));
                }
                return lines;
            }

            return Enumerable.Empty<string>();
        }

        private static IEnumerable<string> SplitLines(string text)
        {
            if (string.IsNullOrWhiteSpace(text))
            {
                return Enumerable.Empty<string>();
            }

            return (text ?? string.Empty)
                .Replace("\r\n", "\n")
                .Replace("\r", "\n")
                .Split(new[] { '\n' }, StringSplitOptions.RemoveEmptyEntries)
                .Select(s => (s ?? string.Empty).Trim())
                .Where(s => s.Length > 0);
        }

        private static string SimplifyMText(string contents)
        {
            if (string.IsNullOrEmpty(contents))
            {
                return string.Empty;
            }

            var s = contents
                .Replace("\\P", "\n")
                .Replace("\\p", "\n")
                .Replace("\\~", " ");

            s = s.Replace("{", string.Empty).Replace("}", string.Empty);
            s = MTextFormatRegex.Replace(s, string.Empty);
            return s;
        }

        private static void TryParseLine(string line, DropdownOptions options, TemplateAnnotationExtractionSummary summary)
        {
            if (string.IsNullOrWhiteSpace(line))
            {
                return;
            }

            var m = FieldRegex.Match(line);
            if (!m.Success)
            {
                return;
            }

            var key = m.Groups[1].Value;
            var rawVal = m.Groups[2].Value;
            var values = SplitValues(rawVal);

            if (values.Count == 0)
            {
                return;
            }

            summary.MatchedLineCount++;

            switch (key)
            {
                case "交付状态":
                    options.DeliveryStatuses.AddRange(values);
                    break;
                case "工艺方法":
                    options.ProcessMethods.AddRange(values);
                    break;
                case "结构特征":
                    options.StructuralFeatures.AddRange(values);
                    break;
            }
        }

        private static List<string> SplitValues(string raw)
        {
            if (string.IsNullOrWhiteSpace(raw))
            {
                return new List<string>();
            }

            var parts = Regex.Split(raw, @"\s*[;；,，\|、/]+\s*")
                .Select(s => (s ?? string.Empty).Trim())
                .Where(s => s.Length > 0)
                .ToList();

            return parts;
        }
    }
}