using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using NTERA.Engine.Compiler;

namespace NTERA.Engine.Runtime
{
	public class JITCompiler : IExecutionProvider
	{
		public ICollection<FunctionDefinition> DefinedProcedures { get; protected set; }
		public ICollection<FunctionDefinition> DefinedFunctions { get; protected set; }
		public ICollection<FunctionVariable> DefinedConstants { get; protected set; }
		public CSVDefinition CSVDefinition { get; protected set; }

		public Dictionary<FunctionDefinition, ExecutionNode[]> CompiledProcedures { get; protected set; } = new Dictionary<FunctionDefinition, ExecutionNode[]>();

		public string InputDirectory { get; }

		public static int Threads = 4;

		public JITCompiler(string path)
		{
			InputDirectory = path;

			Compile();
		}

		protected void Compile()
		{
			string csvPath = Path.Combine(InputDirectory, "CSV");
			string erbPath = Path.Combine(InputDirectory, "ERB");

			var csvDefinition = new CSVDefinition();

			Console.WriteLine("Preprocessing CSV files...");


			foreach (var file in Directory.EnumerateFiles(csvPath, "*.csv", SearchOption.AllDirectories))
			{
				string path = Path.GetFileNameWithoutExtension(file);

				if (path.EndsWith("_TR"))
					continue;

				Preprocessor.ProcessCSV(csvDefinition, path, File.ReadLines(file, Encoding.UTF8));
			}

			Console.WriteLine("Preprocessing header files...");

			ConcurrentBag<FunctionVariable> preprocessedConstants = new ConcurrentBag<FunctionVariable>();

#if DEBUG
			foreach (var file in Directory.EnumerateFiles(erbPath, "*.erh", SearchOption.AllDirectories))
#else
			Parallel.ForEach(Directory.EnumerateFiles(erbPath, "*.erh", SearchOption.AllDirectories), new ParallelOptions
			{
				MaxDegreeOfParallelism = Threads
			}, file =>
#endif
			{
				foreach (var variable in Preprocessor.PreprocessHeaderFile(File.ReadAllText(file)))
					preprocessedConstants.Add(variable);
#if DEBUG
			}
#else
			});
#endif

			Console.WriteLine("Preprocessing functions...");

			ConcurrentDictionary<FunctionDefinition, string> preprocessedFunctions = new ConcurrentDictionary<FunctionDefinition, string>();

#if DEBUG
			foreach (var file in Directory.EnumerateFiles(erbPath, "*.erb", SearchOption.AllDirectories))
#else
			Parallel.ForEach(Directory.EnumerateFiles(erbPath, "*.erb", SearchOption.AllDirectories), new ParallelOptions
			{
				MaxDegreeOfParallelism = Threads
			}, file =>
#endif
			{
				foreach (var kv in Preprocessor.PreprocessCodeFile(File.ReadAllText(file), Path.GetFileName(file), preprocessedConstants.ToArray()))
					preprocessedFunctions[kv.Key] = kv.Value;
#if DEBUG
			}
#else
			});
#endif
			DefinedProcedures = preprocessedFunctions.Select(kv => kv.Key).ToArray();
			var DeclaredProcedures = preprocessedFunctions.ToDictionary(kv => kv.Key, kv => kv.Value);

			var declaredFunctions = BaseDefinitions.DefaultGlobalFunctions.ToList();
			declaredFunctions.AddRange(DeclaredProcedures.Keys.Where(x => x.IsReturnFunction));

			var procedures = DeclaredProcedures.Keys.Where(x => !x.IsReturnFunction).ToList();


			Console.WriteLine("Compiling functions...");

#if DEBUG
			foreach (var kv in DeclaredProcedures)
#else
			Parallel.ForEach(DeclaredProcedures, new ParallelOptions
			{
				MaxDegreeOfParallelism = Threads
			}, kv =>
#endif
			{
				Parser parser = new Parser(kv.Value, kv.Key, declaredFunctions, procedures, BaseDefinitions.DefaultGlobalVariables, kv.Key.Variables, BaseDefinitions.DefaultKeywords, csvDefinition, preprocessedConstants.ToArray());

				var nodes = parser.Parse(out var localErrors, out var localWarnings);

				if (localErrors.Count > 0)
					throw new ParserException($"Failed to compile '{kv.Key.Name}'");

				CompiledProcedures.Add(kv.Key, nodes.ToArray());
#if DEBUG
			}
#else
			});
#endif
		}

		public IEnumerable<ExecutionNode> GetExecutionNodes(FunctionDefinition function)
		{
			return CompiledProcedures[function];
		}
	}
}