using System.Collections.Generic;
using System.Linq;

namespace NTERA.Interpreter.Compiler
{
	public static class Preprocessor
	{
		public static IDictionary<FunctionDefinition, string> PreprocessFile(string contents, string filename)
		{
			Dictionary<FunctionDefinition, string> procs = new Dictionary<FunctionDefinition, string>();

			Lexer lexer = new Lexer(contents);

			Marker startMarker = lexer.TokenMarker;
			string currentDefinitionName = null;
			List<FunctionParameter> currentDefinitionParameters = new List<FunctionParameter>();
			List<FunctionVariable> currentDefinitionVariables = new List<FunctionVariable>();
			bool isReturnFunction = false;

			void Commit()
			{
				if (currentDefinitionName != null)
				{
					string procBody = contents.Substring(startMarker.Pointer,
						lexer.TokenMarker.Pointer - startMarker.Pointer);

					var definition = new FunctionDefinition(currentDefinitionName,
						currentDefinitionParameters.ToArray(),
						currentDefinitionVariables.ToArray(),
						isReturnFunction,
						filename,
						startMarker);

					procs.Add(definition, procBody);

					isReturnFunction = false;
					currentDefinitionName = null;
					currentDefinitionParameters.Clear();
				}
			}

			using (var enumerator = lexer.GetEnumerator())
			{
				do
				{
					if (lexer.TokenMarker.Column != 1)
						continue;

					if (enumerator.Current == Token.Function)
					{
						Commit();

						startMarker = lexer.TokenMarker;

						enumerator.MoveNext();
						if (enumerator.Current != Token.Identifer)
							throw new ParserException("Invalid function declaration - Expected an identifier", lexer.TokenMarker);

						currentDefinitionName = lexer.Identifer;

						enumerator.MoveNext();
						if (enumerator.Current == Token.NewLine
							|| enumerator.Current == Token.EOF)
							continue;

						if (enumerator.Current != Token.LParen
							&& enumerator.Current != Token.Comma)
							throw new ParserException("Invalid function declaration", lexer.TokenMarker);

						enumerator.MoveNext();

						if (enumerator.Current != Token.Identifer
							&& enumerator.Current != Token.RParen)
							throw new ParserException("Invalid function declaration", lexer.TokenMarker);

						while (enumerator.Current == Token.Identifer)
						{
							string parameterName = lexer.Identifer;
							List<string> indices = new List<string>();
							Value? defaultValue = null;

							enumerator.MoveNext();

							while (enumerator.Current == Token.Colon
								   && enumerator.MoveNext())
							{
								if (enumerator.Current == Token.Value)
								{
									indices.Add(lexer.Value.Type == ValueType.Real
										? ((int)lexer.Value).ToString()
										: lexer.Value.String);
								}
								else if (enumerator.Current == Token.Identifer)
								{
									indices.Add(lexer.Identifer);
								}

								enumerator.MoveNext();
							}

							if (enumerator.Current == Token.Equal)
							{
								enumerator.MoveNext();

								bool hasUnaryMinus = false;

								if (enumerator.Current == Token.Minus)
								{
									hasUnaryMinus = true;
									enumerator.MoveNext();
								}

								if (enumerator.Current == Token.Identifer)
								{
									defaultValue = lexer.Identifer;
								}
								else if (enumerator.Current == Token.Value)
								{
									defaultValue = lexer.Value;

									if (hasUnaryMinus)
									{
										if (defaultValue.Value.Type == ValueType.Real)
											defaultValue = defaultValue * -1;
										else
											defaultValue = "-" + defaultValue;
									}
								}
								else
									throw new ParserException("Invalid function declaration", lexer.TokenMarker);

								enumerator.MoveNext();
							}

							if (enumerator.Current == Token.Comma
								|| enumerator.Current == Token.RParen)
							{
								enumerator.MoveNext();
							}
							else if (enumerator.Current != Token.NewLine
									 && enumerator.Current != Token.EOF)
								throw new ParserException("Invalid function declaration", lexer.TokenMarker);

							currentDefinitionParameters.Add(new FunctionParameter(parameterName, indices.ToArray(), defaultValue));
						}

						if (enumerator.Current == Token.RParen)
							enumerator.MoveNext();

						if (enumerator.Current != Token.NewLine
							&& enumerator.Current != Token.EOF)
							throw new ParserException("Invalid function declaration", lexer.TokenMarker);
					}
					else if (enumerator.Current == Token.Sharp)
					{
						enumerator.MoveNext();

						switch (enumerator.Current)
						{
							case Token.Dims:
							case Token.Dim:
							{
								bool isString = enumerator.Current != Token.Dim;

								enumerator.MoveNext();
								VariableType variableType = VariableType.None;

								while (enumerator.Current == Token.Const
									   || enumerator.Current == Token.Ref
									   || enumerator.Current == Token.Dynamic)
								{
									if (enumerator.Current == Token.Const)
										variableType |= VariableType.Constant;
									else if (enumerator.Current == Token.Ref)
										variableType |= VariableType.Reference;
									else if (enumerator.Current == Token.Dynamic)
										variableType |= VariableType.Dynamic;

									enumerator.MoveNext();
								}

								string variable = lexer.Identifer;

								enumerator.MoveNext();
								Value? defaultValue = null;

								if (enumerator.Current == Token.Comma)
								{
									while (enumerator.MoveNext()
										   && enumerator.Current != Token.Equal
										   && enumerator.Current != Token.NewLine
										   && enumerator.Current != Token.EOF)
									{
									}

									//arraySize = (int)lexer.Expression().Real;
								}

								if (enumerator.Current == Token.Equal)
								{
									enumerator.MoveNext();

									if (isString)
										lexer.Type = LexerType.String;


									defaultValue = lexer.Expression();

									lexer.Type = LexerType.Both;
								}
								else if (enumerator.Current != Token.NewLine
										 && enumerator.Current != Token.EOF)
								{
									throw new ParserException("Invalid function declaration", lexer.TokenMarker);
								}

								currentDefinitionVariables.Add(new FunctionVariable(variable,
									isString ? ValueType.String : ValueType.Real,
									variableType,
									defaultValue));

								break;
							}
							case Token.ReturnFunction:
							{
								isReturnFunction = true;
								break;
							}
						}
					}
				} while (enumerator.MoveNext());
			}

			Commit();

			return procs;
		}

		public static IList<IList<string>> ProcessCSV(IEnumerable<string> lines)
		{
			List<IList<string>> csv = new List<IList<string>>();

			foreach (var line in lines)
			{
				if (string.IsNullOrWhiteSpace(line)
					|| line[0] == ';')
					continue;

				string newLine = line;

				int commentIndex = line.IndexOf(';');

				if (commentIndex >= 0)
					newLine = line.Substring(0, commentIndex);

				string[] split = newLine.Split(',');

				csv.Add(split.ToList());
			}

			return csv;
		}
	}
}