using System;
using System.Collections.ObjectModel;
using System.Text.RegularExpressions;

using YesNt.Interpreter.Enums;
using YesNt.Interpreter.Runtime;
using YesNt.Interpreter.Utilities;

namespace YesNt.CodeEditor
{
    internal class SyntaxHighlighter
    {
        private readonly ReadOnlyCollection<StatementInformation> statementInformation;

        public SyntaxHighlighter(ReadOnlyCollection<StatementInformation> statementInformation)
        {
            this.statementInformation = statementInformation;
        }

        public void Write(string input)
        {
            input = input.Replace("\0", string.Empty);

            if (input.StartsWith('#'))
            {
                input = AddColorInformation(input, input, ConsoleColor.Gray, SearchMode.Exact);
            }
            else
            {
                MatchCollection matches = Regex.Matches(input, @"!!.");
                for (int i = 0; i < matches.Count; i++)
                {
                    input = AddColorInformation(input, matches[i].Value, Console.ForegroundColor, SearchMode.Contains);
                }

                foreach (StatementInformation statement in statementInformation)
                {
                    if (statement.IgnoreSyntaxHighlighting)
                    {
                        continue;
                    }

                    string name = statement.SpaceAround switch
                    {
                        SpaceAround.StartEnd => $" {statement.Name.Trim()} ",
                        SpaceAround.Start => $" {statement.Name.Trim()}",
                        SpaceAround.End => $"{statement.Name.Trim()} ",
                        _ => statement.Name
                    };
                    input = input.TrimEnd();
                    if (statement.SearchMode == SearchMode.StartOfLine && input.StartsWith(name))
                    {
                        if (statement.Seperator is not null && input.Contains(statement.Seperator))
                        {
                            input = AddColorInformation(input, statement.Seperator, statement.Color, SearchMode.StartOfLine);
                        }
                        else if (statement.Seperator is not null)
                        {
                            continue;
                        }
                        input = AddColorInformation(input, input[..name.Length], statement.Color, statement.SearchMode);
                    }
                    if (statement.SearchMode == SearchMode.Contains && $" {input} ".Contains(name))
                    {
                        if (statement.Seperator is not null && input.Contains(statement.Seperator))
                        {
                            input = AddColorInformation(input, statement.Seperator, statement.Color, SearchMode.StartOfLine);
                        }
                        else if (statement.Seperator is not null)
                        {
                            continue;
                        }
                        input = AddColorInformation($"{input} ", $"{input} ".Substring($"{input} ".IndexOf(name), name.Length), statement.Color, statement.SearchMode);
                    }
                    if (statement.SearchMode == SearchMode.EndOfLine && input.EndsWith(name))
                    {
                        if (statement.Seperator is not null && input.Contains(statement.Seperator))
                        {
                            input = AddColorInformation(input, statement.Seperator, statement.Color, SearchMode.StartOfLine);
                        }
                        else if (statement.Seperator is not null)
                        {
                            continue;
                        }
                        input = AddColorInformation(input, input[^name.Length..], statement.Color, statement.SearchMode);
                    }
                    if (statement.SearchMode == SearchMode.Exact && input.Equals(name))
                    {
                        if (statement.Seperator is not null && input.Contains(statement.Seperator))
                        {
                            input = AddColorInformation(input, statement.Seperator, statement.Color, SearchMode.StartOfLine);
                        }
                        else if (statement.Seperator is not null)
                        {
                            continue;
                        }
                        input = AddColorInformation(input, input, statement.Color, statement.SearchMode);
                    }
                }

                matches = Regex.Matches(input, @">[a-zA-Z0-9]+");
                for (int i = 0; i < matches.Count; i++)
                {
                    input = AddColorInformation(input, matches[i].Value, ConsoleColor.Cyan, SearchMode.Contains);
                }

                matches = Regex.Matches(input, @"^<[a-zA-Z0-9]+");
                for (int i = 0; i < matches.Count; i++)
                {
                    input = AddColorInformation(input, matches[i].Value, ConsoleColor.DarkCyan, SearchMode.StartOfLine);
                }

                matches = Regex.Matches(input, @"^!<[a-zA-Z0-9]+");
                for (int i = 0; i < matches.Count; i++)
                {
                    input = AddColorInformation(input, matches[i].Value, ConsoleColor.Blue, SearchMode.StartOfLine);
                }
            }

            foreach (string part in input.Split("\0"))
            {
                ConsoleColor consoleColor;
                string messagePart = part;

                string stringColor = Regex.Match(messagePart, "(?<=(\\r))(.*)(?=\\r)").Value;
                bool succ = int.TryParse(stringColor, out int colorIndex);
                if (succ && colorIndex >= 0 && colorIndex < 16)
                {
                    messagePart = messagePart.Replace($"\r{stringColor}\r", string.Empty);
                    consoleColor = (ConsoleColor)colorIndex;
                }
                else
                {
                    consoleColor = ConsoleColor.White;
                }

                if (consoleColor == Console.BackgroundColor)
                {
                    consoleColor = ConsoleColor.White;
                }
                Console.ForegroundColor = consoleColor;
                Console.Write(messagePart);
            }
            Console.ForegroundColor = ConsoleColor.Gray;
        }

        private static string AddColorInformation(string originalString, string value, ConsoleColor color, SearchMode searchMode)
        {
            int spacesAtEnd = value.WhiteSpaceAtEnd();
            string reult = searchMode switch
            {
                SearchMode.StartOfLine => originalString.ReplaceFirstOccurrence(value, $"\0\r{(int)color}\r{value.TrimEnd()}\0" + new string(' ', spacesAtEnd)),
                SearchMode.EndOfLine => originalString.ReplaceLastOccurrence(value, $"\0\r{(int)color}\r{value.TrimEnd()}\0" + new string(' ', spacesAtEnd)),
                _ => originalString.Replace(value, $"\0\r{(int)color}\r{value.TrimEnd()}\0" + new string(' ', spacesAtEnd))
            };
            return reult;
        }
    }
}