using Cryville.Common.Culture;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace Cryville.Common.Font {
	public abstract class FontManager {
		public IReadOnlyDictionary<string, IReadOnlyCollection<Typeface>> MapFullNameToTypeface { get; private set; }
		public IReadOnlyDictionary<string, IReadOnlyCollection<Typeface>> MapNameToTypefaces { get; private set; }
		public FontManager() {
			var map1 = new Dictionary<string, List<Typeface>>();
			var map2 = new Dictionary<string, List<Typeface>>();
			foreach (var f in EnumerateAllTypefaces()) {
				List<Typeface> set1;
				if (!map1.TryGetValue(f.FullName, out set1)) {
					map1.Add(f.FullName, set1 = new List<Typeface>());
				}
				set1.Add(f);
				List<Typeface> set2;
				if (!map2.TryGetValue(f.FamilyName, out set2)) {
					map2.Add(f.FamilyName, set2 = new List<Typeface>());
			}
				set2.Add(f);
			}
			MapFullNameToTypeface = map1.ToDictionary(i => i.Key, i => (IReadOnlyCollection<Typeface>)i.Value);
			MapNameToTypefaces = map2.ToDictionary(i => i.Key, i => (IReadOnlyCollection<Typeface>)i.Value);
		}
		protected abstract IEnumerable<Typeface> EnumerateAllTypefaces();
		public abstract IEnumerable<Typeface> MatchScript(string script = null);
		public abstract IEnumerable<Typeface> MatchFamily(string[] candidates);
		protected static IEnumerable<Typeface> ScanDirectoryForTypefaces(string dir) {
			foreach (var f in new DirectoryInfo(dir).EnumerateFiles()) {
				FontFile file;
				try {
					file = FontFile.Create(f);
				}
				catch (InvalidDataException) {
					continue;
				}
				if (file == null) continue;
				var enumerator = file.GetEnumerator();
				while (enumerator.MoveNext()) {
					Typeface ret;
					try {
						ret = enumerator.Current;
					}
					catch (InvalidDataException) {
						continue;
					}
					yield return ret;
				}
				file.Close();
			}
		}
	}
	public class FontManagerAndroid : FontManager {
		protected override IEnumerable<Typeface> EnumerateAllTypefaces() {
			return ScanDirectoryForTypefaces("/system/fonts");
		}

		public override IEnumerable<Typeface> MatchScript(string script = null) {
			throw new NotImplementedException();
		}

		public override IEnumerable<Typeface> MatchFamily(string[] candidates) {
			throw new NotImplementedException();
		}
	}
	public class FontManagerWindows : FontManager {
		public static Dictionary<string, List<string>> MapScriptToTypefaces = new Dictionary<string, List<string>>();

		static FontManagerWindows() {
			if (Environment.OSVersion.Platform != PlatformID.Win32NT) return;
			ScriptUtils.FillKeysWithScripts(MapScriptToTypefaces, () => new List<string>());
			// Reference: https://github.com/chromium/chromium/blob/main/third_party/blink/renderer/platform/fonts/win/font_fallback_win.cc
			MapScriptToTypefaces["zyyy"].Insert(0, "SimSun"); // Custom
			MapScriptToTypefaces["zyyy"].Insert(0, "SimHei"); // Custom
			MapScriptToTypefaces["zyyy"].Insert(0, "Arial");
			MapScriptToTypefaces["zyyy"].Insert(0, "Times New Roman");
			MapScriptToTypefaces["zyyy"].Insert(0, "Segoe UI"); // Custom
			MapScriptToTypefaces["arab"].Insert(0, "Tahoma");
			MapScriptToTypefaces["cyrl"].Insert(0, "Times New Roman");
			MapScriptToTypefaces["grek"].Insert(0, "Times New Roman");
			MapScriptToTypefaces["hebr"].Insert(0, "David");
			MapScriptToTypefaces["jpan"].Insert(0, "MS PGothic");
			MapScriptToTypefaces["latn"].Insert(0, "Times New Roman");
			MapScriptToTypefaces["hans"].Insert(0, "SimSun");
			MapScriptToTypefaces["hans"].Insert(0, "SimHei"); // Custom
			MapScriptToTypefaces["thai"].Insert(0, "Tahoma");
			MapScriptToTypefaces["hans"].Insert(0, "PMingLiU");
			// Reference: https://learn.microsoft.com/en-us/globalization/input/font-support
			var ver = Environment.OSVersion.Version;
			if (ver >= new Version(5, 0)) { // Windows 2000
				MapScriptToTypefaces["armn"].Insert(0, "Sylfaen");
				MapScriptToTypefaces["deva"].Insert(0, "Mangal");
				MapScriptToTypefaces["geor"].Insert(0, "Sylfaen");
				MapScriptToTypefaces["taml"].Insert(0, "Latha");
			}
			if (ver >= new Version(5, 1)) { // Windows XP
				MapScriptToTypefaces["gujr"].Insert(0, "Shruti");
				MapScriptToTypefaces["guru"].Insert(0, "Raavi");
				MapScriptToTypefaces["knda"].Insert(0, "Tunga");
				MapScriptToTypefaces["syrc"].Insert(0, "Estrangelo Edessa");
				MapScriptToTypefaces["telu"].Insert(0, "Gautami");
				MapScriptToTypefaces["thaa"].Insert(0, "MV Boli");
				// SP2
				MapScriptToTypefaces["beng"].Insert(0, "Vrinda");
				MapScriptToTypefaces["mlym"].Insert(0, "Kartika");
			}
			if (ver >= new Version(6, 0)) { // Windows Vista
				MapScriptToTypefaces["cans"].Insert(0, "Euphemia");
				MapScriptToTypefaces["cher"].Insert(0, "Plantagenet");
				MapScriptToTypefaces["ethi"].Insert(0, "Nyala");
				MapScriptToTypefaces["khmr"].Insert(0, "DaunPenh MoolBoran");
				MapScriptToTypefaces["laoo"].Insert(0, "DokChampa");
				MapScriptToTypefaces["mong"].Insert(0, "Mongolian Baiti");
				MapScriptToTypefaces["orya"].Insert(0, "Kalinga");
				MapScriptToTypefaces["sinh"].Insert(0, "Iskoola Pota");
				MapScriptToTypefaces["tibt"].Insert(0, "Microsoft Himalaya");
				MapScriptToTypefaces["yiii"].Insert(0, "Microsoft Yi Baiti");
				MapScriptToTypefaces["arab"].Insert(0, "Segoe UI");
				MapScriptToTypefaces["cyrl"].Insert(0, "Segoe UI");
				MapScriptToTypefaces["grek"].Insert(0, "Segoe UI");
				MapScriptToTypefaces["latn"].Insert(0, "Segoe UI");
				MapScriptToTypefaces["hans"].Add("SimSun-ExtB");
				MapScriptToTypefaces["hant"].Add("MingLiU-ExtB");
				MapScriptToTypefaces["hant"].Add("MingLiU_HKSCS-ExtB");
				MapScriptToTypefaces["arab"].Add("Microsoft Uighur");
				MapScriptToTypefaces["zmth"].Insert(0, "Cambria Math");
				// Reference: https://en.wikipedia.org/wiki/List_of_CJK_fonts
				MapScriptToTypefaces["jpan"].Insert(0, "Meiryo");
				MapScriptToTypefaces["hans"].Insert(0, "Microsoft YaHei");
			}
			if (ver >= new Version(6, 1)) { // Windows 7
				MapScriptToTypefaces["brai"].Insert(0, "Segoe UI Symbol");
				MapScriptToTypefaces["dsrt"].Insert(0, "Segoe UI Symbol");
				MapScriptToTypefaces["talu"].Insert(0, "Microsoft New Tai Lue");
				MapScriptToTypefaces["ogam"].Insert(0, "Segoe UI Symbol");
				MapScriptToTypefaces["osma"].Insert(0, "Ebrima");
				MapScriptToTypefaces["phag"].Insert(0, "Microsoft PhagsPa");
				MapScriptToTypefaces["runr"].Insert(0, "Segoe UI Symbol");
				MapScriptToTypefaces["zsym"].Insert(0, "Segoe UI Symbol");
				MapScriptToTypefaces["tale"].Insert(0, "Microsoft Tai Le");
				MapScriptToTypefaces["tfng"].Insert(0, "Ebrima");
				MapScriptToTypefaces["vaii"].Insert(0, "Ebrima");
			}
			if (ver >= new Version(6, 2)) { // Windows 8
				MapScriptToTypefaces["glag"].Insert(0, "Segoe UI Symbol");
				MapScriptToTypefaces["goth"].Insert(0, "Segoe UI Symbol");
				MapScriptToTypefaces["hang"].Add("Malgun Gothic");
				MapScriptToTypefaces["ital"].Insert(0, "Segoe UI Symbol");
				MapScriptToTypefaces["lisu"].Insert(0, "Segoe UI");
				MapScriptToTypefaces["mymr"].Insert(0, "Myanmar Text");
				MapScriptToTypefaces["nkoo"].Insert(0, "Ebrima");
				MapScriptToTypefaces["orkh"].Insert(0, "Segoe UI Symbol");
				MapScriptToTypefaces["ethi"].Insert(0, "Ebrima");
				MapScriptToTypefaces["cans"].Insert(0, "Gadugi");
				MapScriptToTypefaces["hant"].Insert(0, "Microsoft JhengHei UI");
				MapScriptToTypefaces["hans"].Insert(0, "Microsoft YaHei UI");
				MapScriptToTypefaces["beng"].Insert(0, "Nirmala UI");
				MapScriptToTypefaces["deva"].Insert(0, "Nirmala UI");
				MapScriptToTypefaces["gujr"].Insert(0, "Nirmala UI");
				MapScriptToTypefaces["guru"].Insert(0, "Nirmala UI"); // NOT DOCUMENTED, UNVERIFIED
				MapScriptToTypefaces["knda"].Insert(0, "Nirmala UI"); // NOT DOCUMENTED, UNVERIFIED
				MapScriptToTypefaces["mlym"].Insert(0, "Nirmala UI");
				MapScriptToTypefaces["orya"].Insert(0, "Nirmala UI");
				MapScriptToTypefaces["sinh"].Insert(0, "Nirmala UI"); // NOT DOCUMENTED, UNVERIFIED
				MapScriptToTypefaces["taml"].Insert(0, "Nirmala UI"); // NOT DOCUMENTED, UNVERIFIED
				MapScriptToTypefaces["telu"].Insert(0, "Nirmala UI");
				MapScriptToTypefaces["armn"].Insert(0, "Segoe UI");
				MapScriptToTypefaces["geor"].Insert(0, "Segoe UI");
				MapScriptToTypefaces["hebr"].Insert(0, "Segoe UI");
			}
			if (ver >= new Version(6, 3)) { // Windows 8.1
				MapScriptToTypefaces["bugi"].Insert(0, "Leelawadee UI");
				MapScriptToTypefaces["copt"].Insert(0, "Segoe UI Symbol");
				MapScriptToTypefaces["java"].Insert(0, "Javanese Text");
				MapScriptToTypefaces["merc"].Insert(0, "Segoe UI Symbol");
				MapScriptToTypefaces["olck"].Insert(0, "Nirmala UI");
				MapScriptToTypefaces["sora"].Insert(0, "Nirmala UI");
				MapScriptToTypefaces["khmr"].Insert(0, "Leelawadee UI");
				MapScriptToTypefaces["laoo"].Insert(0, "Leelawadee UI");
				MapScriptToTypefaces["thai"].Insert(0, "Leelawadee UI");
				MapScriptToTypefaces["zsye"].Insert(0, "Segoe UI Emoji");
			}
			if (ver >= new Version(10, 0)) { // Windows 10
				MapScriptToTypefaces["brah"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["cari"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["cprt"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["egyp"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["armi"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["phli"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["prti"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["khar"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["lyci"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["lydi"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["phnx"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["xpeo"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["sarb"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["shaw"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["xsux"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["ugar"].Insert(0, "Segoe UI Historic");
				// Segoe UI Symbol -> Segoe UI Historic
				MapScriptToTypefaces["glag"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["goth"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["merc"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["ogam"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["ital"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["orkh"].Insert(0, "Segoe UI Historic");
				MapScriptToTypefaces["runr"].Insert(0, "Segoe UI Historic");
				//
				MapScriptToTypefaces["jpan"].Insert(0, "Yu Gothic UI");
				MapScriptToTypefaces["zsym"].Add("Segoe MDL2 Assets");
			}
		}

		protected override IEnumerable<Typeface> EnumerateAllTypefaces() {
			return ScanDirectoryForTypefaces("C:/Windows/Fonts");
		}

		public override IEnumerable<Typeface> MatchScript(string script = null) {
			if (string.IsNullOrEmpty(script)) script = ScriptUtils.UltimateFallbackScript;
			List<string> candidates;
			IEnumerable<string> candidateScripts = new string[] { script };
			while (candidateScripts != null) {
				foreach (var candidateScript in candidateScripts) {
					if (MapScriptToTypefaces.TryGetValue(candidateScript, out candidates)) {
						foreach (var candidate in candidates) {
							Typeface typeface;
							if (MapFullNameToTypeface.TryGetValue(candidate, out typeface)) {
								yield return typeface;
							}
							IReadOnlyCollection<Typeface> typefaces;
							if (MapNameToTypefaces.TryGetValue(candidate, out typefaces)) {
								foreach (var typeface2 in typefaces) {
									if (typeface2 == typeface) continue;
									yield return typeface2;
								}
							}
						}
					}
				}
				candidateScripts = ScriptUtils.EnumerateFallbackScripts(script);
			}
		}

		public override IEnumerable<Typeface> MatchFamily(string[] candidates) {
			throw new NotImplementedException();
		}
	}
}