using System;
using System.Collections.Generic;
using System.IO;
using System.Text;

namespace Cryville.Common.Font {
	public abstract class FontTable<T> {
		protected UInt32 Offset { get; private set; }
		protected BinaryReader Reader { get; private set; }

		protected FontTable(BinaryReader reader, UInt32 offset) {
			Reader = reader;
			Offset = offset;
			reader.BaseStream.Position = offset;
		}
		public abstract IReadOnlyList<T> GetItems();
	}
	public abstract class FontTable<T, U> : FontTable<T> {
		protected FontTable(BinaryReader reader, UInt32 offset) : base(reader, offset) { }
		public abstract U GetSubTable(T item);
	}
	public sealed class TTCHeader : FontTable<UInt32, TableDirectory> {
		readonly String ttcTag;
		readonly UInt16 majorVersion;
		readonly UInt16 minorVersion;
		readonly UInt32 numFonts;
		readonly List<UInt32> tableDirectoryOffsets = new List<UInt32>();
		readonly String dsigTag;
		readonly UInt32 dsigLength;
		readonly UInt32 dsigOffset;
		public TTCHeader(BinaryReader reader, UInt32 offset) : base(reader, offset) {
			ttcTag = reader.ReadTag();
			if (ttcTag != "ttcf") throw new NotImplementedException();
			majorVersion = reader.ReadUInt16();
			minorVersion = reader.ReadUInt16();
			numFonts = reader.ReadUInt32();
			for (UInt32 i = 0; i < numFonts; i++) tableDirectoryOffsets.Add(reader.ReadUInt32());
			if (majorVersion == 2) {
				dsigTag = reader.ReadTag();
				dsigLength = reader.ReadUInt32();
				dsigOffset = reader.ReadUInt32();
			}
		}
		public override IReadOnlyList<UInt32> GetItems() {
			return tableDirectoryOffsets;
		}
		public override TableDirectory GetSubTable(UInt32 item) {
			var i = item;
			return new TableDirectory(Reader, i);
		}
	}
	public sealed class TableDirectory : FontTable<TableRecord, object> {
		readonly UInt32 sfntVersion;
		readonly UInt16 numTables;
		readonly UInt16 searchRange;
		readonly UInt16 entrySelector;
		readonly UInt16 rangeShift;
		readonly List<TableRecord> tableRecords = new List<TableRecord>();
		public TableDirectory(BinaryReader reader, UInt32 offset) : base(reader, offset) {
			sfntVersion = reader.ReadUInt32();
			numTables = reader.ReadUInt16();
			searchRange = reader.ReadUInt16();
			entrySelector = reader.ReadUInt16();
			rangeShift = reader.ReadUInt16();
			for (int i = 0; i < numTables; i++)
				tableRecords.Add(new TableRecord {
					tableTag = reader.ReadTag(),
					checksum = reader.ReadUInt32(),
					offset = reader.ReadUInt32(),
					length = reader.ReadUInt32(),
				});
		}
		public override IReadOnlyList<TableRecord> GetItems() {
			return tableRecords;
		}
		public override object GetSubTable(TableRecord item) {
			switch (item.tableTag) {
				case "name": return new NameTable(Reader, item.offset);
				case "meta": return new MetaTable(Reader, item.offset);
				default: throw new NotImplementedException();
			}
		}
	}
	public struct TableRecord {
		public string tableTag;
		public UInt32 checksum;
		public UInt32 offset;
		public UInt32 length;
	}
	public sealed class NameTable : FontTable<NameRecord> {
		readonly UInt16 version;
		readonly UInt16 count;
		readonly UInt16 storageOffset;
		readonly List<NameRecord> nameRecord = new List<NameRecord>();
		readonly UInt16 langTagCount;
		readonly List<LangTagRecord> langTagRecord = new List<LangTagRecord>();
		public NameTable(BinaryReader reader, UInt32 offset) : base(reader, offset) {
			version = reader.ReadUInt16();
			count = reader.ReadUInt16();
			storageOffset = reader.ReadUInt16();
			for (UInt16 i = 0; i < count; i++)
				nameRecord.Add(new NameRecord {
					platformID = reader.ReadUInt16(),
					encodingID = reader.ReadUInt16(),
					languageID = reader.ReadUInt16(),
					nameID = (NameID)reader.ReadUInt16(),
					length = reader.ReadUInt16(),
					stringOffset = reader.ReadUInt16(),
				});
			if (version == 1) {
				langTagCount = reader.ReadUInt16();
				for (UInt16 i = 0; i < langTagCount; i++)
					langTagRecord.Add(new LangTagRecord {
						length = reader.ReadUInt16(),
						langTagOffset = reader.ReadUInt16(),
					});
			}
			UInt32 origin = (UInt32)reader.BaseStream.Position;
			for (int i = 0; i < nameRecord.Count; i++) nameRecord[i] = nameRecord[i].Load(reader, origin);
			for (int i = 0; i < langTagRecord.Count; i++) langTagRecord[i] = langTagRecord[i].Load(reader, origin);
		}
		public sealed override IReadOnlyList<NameRecord> GetItems() {
			return nameRecord;
		}
	}
	public struct NameRecord {
		public UInt16 platformID;
		public UInt16 encodingID;
		public UInt16 languageID;
		public NameID nameID;
		public UInt16 length;
		public UInt16 stringOffset;
		public String value { get; private set; }
		public NameRecord Load(BinaryReader reader, UInt32 origin) {
			reader.BaseStream.Position = origin + stringOffset;
			Encoding encoding;
			switch (platformID) {
				case 0: encoding = Encoding.BigEndianUnicode; break;
				case 3: encoding = Encoding.BigEndianUnicode; break;
				default: return this;
			}
			value = encoding.GetString(reader.ReadBytes(length));
			return this;
		}
	}
	public enum NameID : UInt16 {
		CopyrightNotice      =  0,
		FontFamilyName       =  1,
		FontSubfamilyName    =  2,
		UniqueFontIdentifier =  3,
		FullFontName         =  4,
		VersionString        =  5,
		PostScriptName       =  6,
		Trademark            =  7,
		ManufacturerName     =  8,
		Designer             =  9,
		Description          = 10,
		URLVendor            = 11,
		URLDesigner          = 12,
		LicenseDescription   = 13,
		LicenseInfoURL       = 14,

		TypographicFamilyName          = 16,
		TypographicSubfamilyName       = 17,
		CompatibleFull                 = 18,
		SampleText                     = 19,
		PostScriptCIDFindfontName      = 20,
		WWSFamilyName                  = 21,
		WWSSubfamilyName               = 22,
		LightBackgroundPalette         = 23,
		DarkBackgroundPalette          = 24,
		VariationsPostScriptNamePrefix = 25,
	}
	public struct LangTagRecord {
		public UInt16 length;
		public UInt16 langTagOffset;
		public String value { get; private set; }
		public LangTagRecord Load(BinaryReader reader, UInt32 origin) {
			reader.BaseStream.Position = origin + langTagOffset;
			value = Encoding.BigEndianUnicode.GetString(reader.ReadBytes(length));
			return this;
		}
	}
	public sealed class MetaTable : FontTable<DataMap> {
		readonly UInt32 version;
		readonly UInt32 flags;
		readonly UInt32 dataMapCount;
		readonly List<DataMap> dataMaps = new List<DataMap>();
		public MetaTable(BinaryReader reader, UInt32 offset) : base(reader, offset) {
			version = reader.ReadUInt32();
			flags = reader.ReadUInt32();
			reader.ReadUInt32();
			dataMapCount = reader.ReadUInt32();
			for (UInt32 i = 0; i < dataMapCount; i++)
				dataMaps.Add(new DataMap {
					tag = reader.ReadTag(),
					dataOffset = reader.ReadUInt32(),
					dataLength = reader.ReadUInt32(),
				});
			for (int i = 0; i < dataMaps.Count; i++) dataMaps[i] = dataMaps[i].Load(reader, offset);
		}
		public sealed override IReadOnlyList<DataMap> GetItems() {
			return dataMaps;
		}
	}
	public struct DataMap {
		public String tag;
		public UInt32 dataOffset;
		public UInt32 dataLength;
		public String value { get; private set; }
		public DataMap Load(BinaryReader reader, UInt32 origin) {
			reader.BaseStream.Position = origin + dataOffset;
			value = Encoding.ASCII.GetString(reader.ReadBytes((int)dataLength));
			return this;
		}
	}
	public static class BinaryReaderExtensions {
		public static string ReadTag(this BinaryReader reader) {
			return Encoding.ASCII.GetString(reader.ReadBytes(4));
		}
	}
}