using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Dynamic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CompilerDesignIFlr1
{
    internal class LR1Creator
    {
        internal string StartSymbol { get; init; }
        internal Dictionary<int, LR1Closure> Closures = [];

        // 终结符
        internal Dictionary<string, LR1Unit> TokenUnit = [];

        // 非终结符 考虑 或 的情况
        internal Dictionary<string, List<LR1Unit>> GrammarUnit = [];

        // First集
        internal Dictionary<string, HashSet<string>> FirstGroup = [];
        internal Dictionary<int, LR1Unit> UnitIndex = [];

        internal LR1Creator(GrammarReader reader)
        {
            TokenUnit.Add("End", new LR1Unit("End", "#"));
            foreach (var (key, value) in reader.SymbolToken)
            {
                TokenUnit.Add(key, new LR1Unit(key, value));
            }
            foreach (var (key, value) in reader.KeyToken)
            {
                TokenUnit.Add(key, new LR1Unit(key, value));
            }
            foreach (var (key, value) in reader.RegexToken)
            {
                TokenUnit.Add(key, new LR1Unit(key, value));
            }
            foreach (var (key, _) in reader.RegularToken)
            {
                if (key.StartsWith("@skip"))
                    continue;
                if (key.StartsWith("@top"))
                    GrammarUnit.Add(key.Substring(5), []);
                else
                    GrammarUnit.Add(key, []);
            }
            string startSymbol = "";
            foreach (var (key, value) in reader.RegularToken)
            {
                if (key.StartsWith("@skip"))
                    continue;
                if (key.StartsWith("@top"))
                {
                    startSymbol = key.Substring(5);
                    GrammarUnitCreate(value, key.Substring(5));
                }
                else
                {
                    GrammarUnitCreate(value, key);
                }
            }
            SetGrammarIndex();
            PrintGrammar();
            foreach (var (key, _) in TokenUnit)
                GetFirst(key);
            foreach (var (key, _) in GrammarUnit)
                GetFirst(key);
            PrintFirst();
            StartSymbol = startSymbol;
            I0Creator();
            CalculateAllClosure();
            PrintClosure(Enumerable.Range(0, Closures.Count).ToArray());
        }

        internal void SetGrammarIndex()
        {
            int id = 0;
            foreach (var (key, units) in GrammarUnit)
            foreach (var unit in units)
            {
                unit.Id = id++;
                UnitIndex[unit.Id] = unit;
            }
        }

        internal void PrintClosure(params int[] index)
        {
            foreach (int t in index)
            {
                //Console.WriteLine($"闭包{t}:");
                Console.WriteLine(Closures[t]);
                //var closure = Closures[t];
                //foreach (var unit in closure.Units)
                //{
                //    Console.Write($"{unit.Name} ::= ");
                //    Console.WriteLine(unit);
                //}
            }
        }

        internal void I0Creator()
        {
            var closure = new LR1Closure(this);
            foreach (var root in GrammarUnit[StartSymbol])
            {
                var res = root.Clone();
                res.Prospect.Add("End");
                closure.Units.Add(res);
            }
            closure.AddMissingUnits();
            //foreach (var (key, value) in GrammarUnit)
            //{
            //    if (key == StartSymbol)
            //        continue;
            //    value.ForEach(x => closure.Units.Add(x.Clone()));
            //}
            closure.CalculateProspects();
            Closures.Add(closure.Index, closure);
        }

        internal HashSet<string> GetFirst(string root)
        {
            if (FirstGroup.TryGetValue(root, out var ans))
                return ans;
            if (GrammarUnit.TryGetValue(root, out var units))
            {
                HashSet<string> res = [];
                foreach (var unit in units)
                {
                    if (FirstGroup.TryGetValue(root, out var list))
                        res.UnionWith(list);
                    else
                    {
                        if (unit.Type == "Token")
                            res.UnionWith(GetFirst(unit.Name));
                        else if (unit.Type == "Grammar")
                        {
                            var val = unit.Grammar.FirstOrDefault();
                            if (val == null)
                                continue;
                            res.UnionWith(GetFirst(val));
                        }
                    }
                }
                FirstGroup.Add(root, res);
                return res;
            }
            else if (TokenUnit.TryGetValue(root, out var unit))
            {
                FirstGroup.Add(root, [unit.Name]);
                return [unit.Name];
            }
            else
            {
                throw new Exception("Grammar can't be recognized. " + root);
            }
        }

        internal void CalculateAllClosure()
        {
            int t = 0;
            bool haveNew = true;
            while (Closures.ContainsKey(t))
            {
                haveNew = false;
                if (Closures.TryGetValue(t, out var closure))
                {
                    List<LR1Closure> nextClosures = closure.NextClosures();
                    if (nextClosures.Count > 0)
                        haveNew = true;
                    nextClosures.ForEach(x => Closures.Add(x.Index, x));
                }
                t++;
            }
            if (!Closures.ContainsKey(t) && haveNew)
                throw new Exception("Really weird. This situation shouldn't be possible.");
        }

        internal string GrammarUnitCreate(string value, string name = "")
        {
            if (value.EndsWith('*') || value.EndsWith('+'))
            {
                string s;
                if (value.StartsWith('(') && value[^2] == ')')
                {
                    s = DeClosure(value.Substring(1, value.Length - 3), value[^1]);
                    if (name != "")
                    {
                        GrammarUnit[name] = [new LR1Unit(name, [s])];
                    }
                    return s;
                }
                else if (value.IndexOf(' ') == -1)
                {
                    s = DeClosure(value.Substring(0, value.Length - 1), value[^1]);
                    if (name != "")
                    {
                        GrammarUnit[name] = [new LR1Unit(name, [s])];
                    }
                    return s;
                }
            }
            bool inParen = false;
            int last = 0;
            name = name.Length == 0 ? NameGenerator(value) : name;
            List<List<string>> ans = [];
            List<string> grammar = [];
            value = value + ' ';
            for (var i = 0; i < value.Length; i++)
            {
                char c = value[i];
                if (inParen && c != ')')
                    continue;
                switch (c)
                {
                    case '(':
                        last = i;
                        inParen = true;
                        break;
                    case ')':
                    {
                        inParen = false;
                        break;
                    }
                    case ' ':
                    {
                        string subValue = value.Substring(last, i - last);
                        last = i + 1;
                        if (GrammarUnit.ContainsKey(subValue.Trim()))
                            grammar.Add(subValue.Trim());
                        else if (TokenUnit.ContainsKey(subValue.Trim()))
                            grammar.Add(subValue.Trim());
                        else
                        {
                            if (subValue.Trim().Length == 0)
                                break;
                            throw new Exception("Grammar can't be recognized. " + subValue);
                        }
                        break;
                    }
                    case '|':
                    {
                        string subValue = value.Substring(last, i - last);
                        if (subValue.Trim().TrimEnd('|').Length != 0)
                        {
                            if (GrammarUnit.ContainsKey(subValue.Trim()))
                                grammar.Add(subValue.Trim());
                            else if (TokenUnit.ContainsKey(subValue.Trim()))
                                grammar.Add(subValue.Trim());
                            else
                                throw new Exception("Grammar can't be recognized. " + subValue);
                        }
                        ans.Add(grammar);
                        grammar = [];
                        last = i + 1;
                        break;
                    }
                    case '*':
                    {
                        string subString = GrammarUnitCreate(value.Substring(last, i - last + 1));
                        grammar.Add(subString);
                        last = i + 1;
                        break;
                    }
                    case '+':
                    {
                        string subString = GrammarUnitCreate(value.Substring(last, i - last + 1));
                        grammar.Add(subString);
                        last = i + 1;
                        break;
                    }
                    default:
                        break;
                }
            }
            if (grammar.Count > 0)
                ans.Add(grammar);
            if (GrammarUnit.TryGetValue(name, out var val))
                GrammarUnit[name] = ToLR1Units(name, ans);
            else
                GrammarUnit.Add(name, ToLR1Units(name, ans));
            return name;
        }

        // 嵌套解包直接报错！！
        internal string DeClosure(string value, char type)
        {
            if (value.IndexOf('+') != -1 || value.IndexOf("*") != -1)
                throw new Exception("Grammar too complex. " + value);
            string name = NameGenerator(value);
            List<List<string>> ans = [];
            List<string> res = [];
            if (type == '*')
            {
                ans.Add([]);
                var grammars = value.Split('|').Select(x => x.Split(' ').Where(x => x.Length != 0));
                foreach (var grammar in grammars)
                {
                    res = [];
                    foreach (var gram in grammar)
                    {
                        if (TokenUnit.ContainsKey(gram) || GrammarUnit.ContainsKey(gram))
                            res.Add(gram);
                        else
                        {
                            Console.WriteLine(gram.Length);
                            throw new Exception("Unknown grammar. " + gram);
                        }
                    }
                    //ans.Add([name,..res]);
                    ans.Add([.. res, name]);
                }
            }
            else if (type == '+')
            {
                var grammars = value.Split('|').Select(x => x.Trim().Split(' '));
                foreach (var grammar in grammars)
                {
                    res = [];
                    foreach (var gram in grammar)
                    {
                        if (TokenUnit.ContainsKey(gram) || GrammarUnit.ContainsKey(gram))
                            res.Add(gram);
                        else
                            throw new Exception("Unknown grammar. " + gram);
                    }
                    ans.Add([.. res]);

                    //ans.Add([name,.. res]);
                    ans.Add([.. res, name]);
                }
            }
            else
            {
                throw new Exception("Unknown type. " + type);
            }
            if (GrammarUnit.TryGetValue(name, out var val))
                GrammarUnit[name] = ToLR1Units(name, ans);
            else
                GrammarUnit.Add(name, ToLR1Units(name, ans));
            return name;
        }

        internal string NameGenerator(string key)
        {
            var list = key.Replace('(', ' ')
                .Replace(')', ' ')
                .Replace('*', ' ')
                .Replace('|', ' ')
                .Replace("  ", " ")
                .Split(' ')
                .Select(x => x.Trim());
            var res = String.Join('_', list);
            for (int i = 0; i < 9; i++)
                if (!GrammarUnit.ContainsKey(res + '_' + i))
                    return res + '_' + i;
            throw new Exception("Grammar too Complex:" + key);
        }

        internal List<LR1Unit> ToLR1Units(string name, List<List<string>> grammars)
        {
            var res = new List<LR1Unit>();
            foreach (var grammar in grammars)
            {
                res.Add(new LR1Unit(name, grammar));
            }
            return res;
        }

        private void PrintGrammar()
        {
            Console.WriteLine("文法：");
            foreach (var (key, value) in GrammarUnit)
            {
                Console.WriteLine("key: " + key);
                foreach (var unit in value)
                {
                    Console.WriteLine("    " + unit);
                }
            }
        }

        internal void PrintFirst()
        {
            Console.WriteLine("First集：");
            foreach (var (key, value) in FirstGroup)
            {
                Console.Write($"{key}: ");
                foreach (var val in value)
                    Console.Write($"{val} ");
                Console.WriteLine();
            }
        }

        internal List<LR1Unit> GetUnits(string name)
        {
            if (TokenUnit.TryGetValue(name, out var unit))
                return [unit];
            if (GrammarUnit.TryGetValue(name, out var units))
                return units;
            throw new Exception($"No Unit Called: {name}");
        }
    }
}