using Convention.RScript.Matcher;
using Convention.RScript.Parser;
using Convention.RScript.Runner;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;

namespace Convention.RScript
{
    public struct RScriptSentence
    {
        public enum Mode
        {
            /// <summary>
            /// 表达式, 格式: 任意合法表达式
            /// </summary>
            Expression,
            /// <summary>
            /// 定义变量, 格式: 类型 变量名 [=Expression]
            /// <para>类型支持: string, int, double, float, bool, var</para>
            /// <para>每层命名空间中不可重复定义变量, 不可使用未定义的变量, 不存在时会自动向上查找上级空间的变量</para>
            /// </summary>
            DefineVariable,
            /// <summary>
            /// 进入新的命名空间, 格式: {
            /// <para>命名空间是一对花括号包裹内容空间, 格式: {...}</para>
            /// </summary>
            EnterNamespace,
            /// <summary>
            /// 退出当前命名空间, 格式: }
            /// <para>命名空间是一对花括号包裹内容空间, 格式: {...}</para>
            /// </summary>
            ExitNamespace,
            /// <summary>
            /// 标签, 格式: label(labelname);
            /// </summary>
            Label,
            /// <summary>
            /// 跳转到指定标签, 格式: goto(boolean,labelname);
            /// <para>判断为真时跳转到labelname</para>
            /// </summary>
            Goto,
            /// <summary>
            /// 跳转到当前命名空间的结束位置, 格式: break(boolean);
            /// </summary>
            Breakpoint,
            /// <summary>
            /// 跳转到上次跳转的位置的后一个位置, 格式: back(boolean);
            /// </summary>
            Backpoint,
            /// <summary>
            /// 命名空间命名, 格式: namespace(labelname){}
            /// </summary>
            NamedSpace,
        }

        public string content;
        public List<string> info;
        public Mode mode;

        public override string ToString()
        {
            return $"{mode.ToString()}/: {content}";
        }
    }

    public interface IRSentenceMatcher
    {
        bool Match(string expression, ref RScriptSentence sentence);
    }

    public interface IRSentenceRunner
    {
        [return: MaybeNull] object Run(ExpressionParser parser, RScriptSentence sentence, RScriptContext context);
    }

    public partial class RScriptContext
    {
        public readonly RScriptImportClass Import;
        public readonly RScriptVariables Variables;
        internal readonly RScriptSentence[] Sentences;
        internal readonly Dictionary<string, int> Labels = new();
        internal readonly Dictionary<int, int> NamespaceLayer = new();
        internal readonly Dictionary<string, int> NamespaceLabels = new();

        public List<IRSentenceMatcher> SentenceParser = new()
        {
            new NamespaceMater(),
            new DefineVariableMatcher(),
            new LabelMatcher(),
            new GotoMatcher(),
            new BreakMatcher(),
            new BackMatcher(),
        };

        public Dictionary<RScriptSentence.Mode, IRSentenceRunner> SentenceRunners = new()
        {
            { RScriptSentence.Mode.DefineVariable, new DefineVariableRunner() },
            { RScriptSentence.Mode.EnterNamespace, new EnterNamespaceRunner() },
            { RScriptSentence.Mode.ExitNamespace, new ExitNamespaceRunner() },
            { RScriptSentence.Mode.Goto, new GoToRunner() },
            { RScriptSentence.Mode.Breakpoint, new BreakpointRunner() },
            { RScriptSentence.Mode.Backpoint, new BackpointRunner() },
            { RScriptSentence.Mode.Expression, new ExpressionRunner() },
            { RScriptSentence.Mode.NamedSpace, new EnterNamedSpaceRunner() },
        };

        private RScriptSentence ParseToSentence(string expression)
        {
            RScriptSentence result = new()
            {
                content = expression,
                mode = RScriptSentence.Mode.Expression
            };
            expression = expression.Trim();
            expression = expression.TrimEnd(';');
            var _ = SentenceParser.Any(matcher => matcher.Match(expression, ref result));
            return result;
        }

        private void BuildUpLabelsAndNamespace()
        {
            Stack<int> namespaceLayers = new();
            string namespaceName = "";
            for (int i = 0, e = Sentences.Length; i != e; i++)
            {
                var sentence = Sentences[i];
                if (string.IsNullOrEmpty(namespaceName))
                {
                    if (sentence.mode == RScriptSentence.Mode.Label)
                    {
                        this.Labels[Sentences[i].content] = i;
                    }
                    else if (sentence.mode == RScriptSentence.Mode.EnterNamespace)
                    {
                        namespaceLayers.Push(i);
                    }
                    else if (sentence.mode == RScriptSentence.Mode.ExitNamespace)
                    {
                        if (namespaceLayers.Count == 0)
                            throw new RScriptRuntimeException("Namespace exit without enter.", i);
                        var enterPointer = namespaceLayers.Pop();
                        this.NamespaceLayer[enterPointer] = i;
                    }
                    else if (sentence.mode == RScriptSentence.Mode.NamedSpace)
                    {
                        namespaceName = sentence.content;
                    }
                }
                else
                {
                    if (sentence.mode == RScriptSentence.Mode.EnterNamespace)
                    {
                        namespaceLayers.Push(i);
                        this.NamespaceLabels[namespaceName] = i;
                        namespaceName = "";
                    }
                    else
                    {
                        throw new RScriptRuntimeException($"Namespace is invalid", i);
                    }
                }
            }
            if (namespaceLayers.Count > 0)
            {
                throw new RScriptRuntimeException("Namespace enter without exit.", namespaceLayers.Peek());
            }
        }

        public class BuildInContext
        {
            private RScriptContext context;
            public BuildInContext(RScriptContext context)
            {
                this.context = context;
            }

            public bool ExistVar(string name)
            {
                return context.Variables.ContainsKey(name);
            }

            public bool ExistNamespace(string name)
            {
                return context.NamespaceLabels.ContainsKey(name);
            }

            public bool ExistLabel(string name)
            {
                return context.Labels.ContainsKey(name);
            }
        }

        public RScriptContext(string[] expressions,
                              RScriptImportClass import = null,
                              RScriptVariables variables = null,
                              List<IRSentenceMatcher> matcher = null,
                              Dictionary<RScriptSentence.Mode, IRSentenceRunner> sentenceRunners = null)
        {
            this.Import = import ?? new();
            this.Variables = variables ?? new();
            this.Variables.Add("context", new(typeof(object), new BuildInContext(this)));
            this.Sentences = (from item in expressions select ParseToSentence(item)).ToArray();
            if (matcher != null)
                this.SentenceParser = matcher;
            if (sentenceRunners != null)
                this.SentenceRunners = sentenceRunners;

            BuildUpLabelsAndNamespace();
        }

        public RScriptSentence CurrentSentence => Sentences[CurrentRuntimePointer];


        internal object RunNextStep(ExpressionParser parser)
        {
            var sentence = CurrentSentence;
            try
            {
                return SentenceRunners.TryGetValue(sentence.mode, out var runner) ? runner.Run(parser, sentence, this) : null;
            }
            catch (RScriptException)
            {
                throw;
            }
            catch (Exception ex)
            {
                throw new RScriptRuntimeException($"Runtime error: {ex.Message}", CurrentRuntimePointer, ex);
            }
        }

        internal readonly Stack<int> RuntimePointerStack = new();
        internal readonly Stack<int> GotoPointerStack = new();
        public int CurrentRuntimePointer { get; internal set; } = 0;
        internal readonly Stack<HashSet<string>> CurrentLocalSpaceVariableNames = new();

        public Dictionary<string, RScriptVariableEntry> GetCurrentVariables()
        {
            Dictionary<string, RScriptVariableEntry> result = new();
            foreach (var (key, value) in Variables)
            {
                result[key] = value;
            }
            return result;
        }

        private void BeforeRun(ExpressionParser parser)
        {
            CurrentLocalSpaceVariableNames.Clear();
            RuntimePointerStack.Clear();
            GotoPointerStack.Clear();
            CurrentLocalSpaceVariableNames.Clear();
            CurrentLocalSpaceVariableNames.Push(new());
            foreach (var staticType in Import)
            {
                parser.context.Imports.AddType(staticType);
            }
            foreach (var (name,varObject) in Variables)
            {
                parser.context.Variables[name] = varObject.data;
            }
        }

        public void Run(ExpressionParser parser)
        {
            BeforeRun(parser);
            for (CurrentRuntimePointer = 0; CurrentRuntimePointer < Sentences.Length; CurrentRuntimePointer++)
            {
                RunNextStep(parser);
            }
            // 更新上下文变量
            foreach (var (varName, varValue) in parser.context.Variables)
            {
                if (Variables.ContainsKey(varName))
                    Variables.SetValue(varName, varValue);
            }
        }

        public IEnumerator RunAsync(ExpressionParser parser)
        {
            BeforeRun(parser);
            for (CurrentRuntimePointer = 0; CurrentRuntimePointer < Sentences.Length; CurrentRuntimePointer++)
            {
                var ret = RunNextStep(parser);
                if (ret is IEnumerator ir)
                {
                    yield return ir;
                }
                yield return null;
            }
            // 更新上下文变量
            foreach (var (varName, varValue) in parser.context.Variables)
            {
                if (Variables.ContainsKey(varName))
                    Variables.SetValue(varName, varValue);
            }
        }
    }
}