using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Newtonsoft.Json;

using LibSearchBox;
using System.Text.RegularExpressions;
using Newtonsoft.Json.Serialization;

namespace SearchBoxCLI
{
	enum OperatingModes
	{
		Query,
		Index,
		Add,
		Remove,
		Update
	}

	enum OutputModes
	{
		Json,
		Text
	}

	class MainClass {
		private static OperatingModes Mode = OperatingModes.Query;
		private static bool Batch = false;
		private static string Name = string.Empty;
		private static IEnumerable<string> Tags;
		private static string SearchIndexFilepath = string.Empty;
		private static TextReader Source = Console.In;
		private static TextReader SourceOld = null, SourceNew = null;
		private static OutputModes OutputMode = OutputModes.Json;

		public static int Main(string[] args)
		{
			List<string> extras = new List<string>();
			for (int i = 0; i < args.Length; i++)
			{
				if (!args[i].StartsWith("-")) {
					extras.Add(args[i]);
					continue;
				}

				switch (args[i].TrimStart("-".ToCharArray())) {
					case "s":
					case "source":
						string sourceFilename = args[++i];
						Source = new StreamReader(sourceFilename);
						Name = Name.Length > 0 ? Name : sourceFilename;
						break;

					case "batch":
						Batch = true;
						break;

					case "old-source":
						SourceOld = new StreamReader(args[++i]);
						break;
					case "new-source":
						string newSourceFilename = args[++i];
						SourceNew = new StreamReader(newSourceFilename);
						Name = Name.Length > 0 ? Name : newSourceFilename;
						break;

					case "tags":
						Tags = Regex.Split(args[++i], @",\s*");
						break;

					case "n":
					case "name":
						Name = args[++i];
						break;

					case "index":
						SearchIndexFilepath = args[++i];
						break;

					case "help":
						return HandleHelp();

					default:
						Console.Error.WriteLine($"Error: Unknown property {args[i]}.");
						return 1;
				}
			}
			if (extras.Count < 1) return HandleHelp();
			string modeText = extras.First(); extras.RemoveAt(0);
			Mode = (OperatingModes)Enum.Parse(typeof(OperatingModes), modeText, true);

			switch (Mode) {
				case OperatingModes.Index: return HandleIndex();
				case OperatingModes.Add: return HandleAdd();
				case OperatingModes.Remove: return HandleRemove();
			}

			return 0;
		}

		private static int HandleHelp()
		{
			Console.WriteLine("SearchBox");
			Console.WriteLine("---------");
			Console.WriteLine("A standalone full-text search engine. Operates on plain text sources.");
			Console.WriteLine();
			Console.WriteLine("Usage:");
			Console.WriteLine("    ./SearchBox.exe {mode} [options]");
			Console.WriteLine();
			Console.WriteLine("Modes:");
			Console.WriteLine("    query     Query a pre-existing inverted search index");
			Console.WriteLine("    index     Generate a raw index of the source document.");
			Console.WriteLine("    add       Add a named document to a search index.");
			Console.WriteLine("    remove    Remove a named document from a search index.");
			Console.WriteLine("    update    Update a named document in a search index.");
			Console.WriteLine();
			Console.WriteLine("Options:");
			Console.WriteLine("    --source, -s    Specifies the path to the source document {index, add}");
			Console.WriteLine("    --old-source    Specifies the path to the old version of the source document to update {update}");
			Console.WriteLine("    --new-source    Specifies the path to the new version of the source document to update {update}");
			Console.WriteLine("    --name, -n      Sets the name of the source document {add, remove}");
			Console.WriteLine("    --index         Specifies the location of the search index to use {add, remove, update}");
			Console.WriteLine("    --tags          Sets the tags to associate with the document. {add, update}");
			Console.WriteLine("    --batch         Enters a mode where the operations to process are specified via the source (by default stdin; change with --source as usual) - one per line in the format \"{filename}|{name}|{tags}\" {add}");
			Console.WriteLine();
			Console.WriteLine("Examples:");
			Console.WriteLine("    cat books/complex_knots.txt | ./SearchBox.exe add --name \"Complex Knots: How to do and undo them\"");
			Console.WriteLine();
			return 1;
		}

		private static int HandleAdd()
		{
			if (Name == string.Empty && !Batch)
			{
				Console.Error.WriteLine("Error: The document name must be specified when reading from stdin!");
				return 1;
			}
			if (SearchIndexFilepath == string.Empty)
			{
				Console.Error.WriteLine("Error: No search index file path specified.");
				return 1;
			}

			// --------------------------------------

			SearchBox searchBox;
			if (!File.Exists(SearchIndexFilepath))
				searchBox = new SearchBox();
			else
				searchBox = JsonConvert.DeserializeObject<SearchBox>(File.ReadAllText(SearchIndexFilepath));


			if (!Batch)
				searchBox.AddDocument(Name, Tags, Source.ReadToEnd());
			else {
				string nextLine = "";
				while ((nextLine = Source.ReadLine()) != null) {
					string[] parts = nextLine.Split('|');
					if (parts[0].Trim().Length == 0)
						continue;
					try {
						searchBox.AddDocument(
							parts[1].Trim(),
							Regex.Split(parts[2], @",\s*"),
							File.ReadAllText(parts[0].Trim())
						);
						Console.Error.WriteLine($"[Searchbox] [add] {parts[0].Trim()}");
					} catch (FileNotFoundException) {
						Console.Error.WriteLine($"Error: Can't find file {parts[2].Trim()}.");
						return 1;
					}
				}
			}

			File.WriteAllText(SearchIndexFilepath, JsonConvert.SerializeObject(searchBox));

			Console.Error.WriteLine($"[Searchbox] [add] {Name} -> {SearchIndexFilepath}");

			return 0;
		}



		private static int HandleRemove()
		{
			if (Name == string.Empty) {
				Console.Error.WriteLine("Error: The document name must be specified when removing a document!");
				return 1;
			}

			// --------------------------------------

			SearchBox searchBox = JsonConvert.DeserializeObject<SearchBox>(
				File.ReadAllText(SearchIndexFilepath)
			);

			searchBox.RemoveDocument(Name);


			File.WriteAllText(SearchIndexFilepath, JsonConvert.SerializeObject(searchBox));

			Console.Error.WriteLine($"[Searchbox] [remove] {Name} <- {SearchIndexFilepath}");

			return 0;
		}

		private static int HandleIndex()
		{
			Index index = new Index(Source.ReadToEnd());
			switch (OutputMode)
			{
				case OutputModes.Json:
					Console.WriteLine(JsonConvert.SerializeObject(index));
					break;
				case OutputModes.Text:
					Console.WriteLine(index);
					break;
			}

			return 0;
		}
	}
}