using System.Data;
using System.Text.RegularExpressions;

namespace etoy
{
    sealed class MetadataTableCsvParser
    {
        const int START_ROW = 1;

        // 正则解析Metadata结构体
        Regex _structRegex = new Regex(@"(?<quote>""?)(\w+)\s*?{([\w\s:;\[\]]+)}(\k<quote>)");
        Regex _structFieldRegex = new Regex(@"(\w+)\s*?:\s*?([\w]+?)\s*?(\[\])?\s*?(;|$)");

        // 正则解析Metadata枚举
        Regex _enumRegex = new Regex(@"(?<quote>""?)(\w+)\s*?{([\w\s=,]+)}(\k<quote>)");
        Regex _enumFieldRegex = new Regex(@"(\w+)\s*?(=\s*?(\d+))?\s*?,?");


        public MetadataTable Parser(DataTable dt, string file)
        {
            int rowCount = dt.Rows.Count;
            int colCount = dt.Columns.Count;

            if (rowCount <= 0 || colCount < 3)
                throw new Exception($"Metadata表结构不合法, Row: {rowCount}, Column: {colCount}");


            Dictionary<string, MetadataStruct> structs = new Dictionary<string, MetadataStruct>();
            List<MetadataRow> rows = new List<MetadataRow>();

            for (int i = START_ROW; i < rowCount; i++)
            {
                MetadataRow row = new MetadataRow();
                row.Row = i;

                for (int j = 0; j < colCount; j++)
                {
                    var cellvalue = dt.Rows[i][j].ToString().ToCellValue();

                    MetadataColumnType type = (MetadataColumnType)j;
                    switch (type)
                    {
                        case MetadataColumnType.Type:
                            row.Type = cellvalue.ToFieldType();
                            break;
                        case MetadataColumnType.Value:
                            row.Value = cellvalue;
                            break;
                        case MetadataColumnType.Description:
                            row.Description = cellvalue;
                            break;
                        default:
                            throw new Exception();
                    }
                }
                rows.Add(row);
            }

            // 解析Struct & Enum
            for (int i = 0, length = rows.Count; i < length; i++)
            {
                var row = rows[i];

                if (string.IsNullOrEmpty(row.Type))
                    throw new Exception($"Metadata 类型为空(行:{i}) {file}");

                if (Enum.TryParse<MetadataStructType>(row.Type, true, out var structType))
                {
                    if (TryParseMetadata(structType, row.Value, out var @struct))
                    {
                        if (structs.ContainsKey(@struct.Name))
                            throw new Exception($"Metadata 类型重复定义了(行:{i}) ({row.Value}) {file}");

                        @struct.StructType = structType;
                        @struct.Description = row.Description;

                        // 两个地方都存, 方便生成代码使用
                        row.Struct = @struct;
                        structs[@struct.Name] = @struct;
                    }
                    else
                        throw new Exception($"Metadata 类型解析失败(行:{i}) ({row.Value}) {file}");
                }
                else
                    throw new Exception($"Metadata 不支持类型({row.Type}), 请修改 {file}");
            }


            MetadataTable table = new MetadataTable();
            table.Structs = structs;
            table.Rows = rows.ToArray();
            table.Path = file;
            table.Name = Path.GetFileNameWithoutExtension(file).ToTableName();
            return table;
        }


        bool TryParseMetadata(MetadataStructType type, string metadata, out MetadataStruct @struct)
        {
            @struct = default;

            bool bRet = false;

            switch (type)
            {
                case MetadataStructType.Struct:
                    bRet = ParseStruct(metadata, out @struct);
                    break;
                case MetadataStructType.Enum:
                    bRet = ParseEnum(metadata, out @struct);
                    break;
            }
            return bRet;
        }

        bool Parse(string metadata, Regex regex, out string typeName, out string typeBody)
        {
            typeName = typeBody = string.Empty;

            Match match = regex.Match(metadata);
            if (!match.Success) return false;

            typeName = match.Groups[1].Value;
            typeBody = match.Groups[2].Value;
            return true;
        }

        bool ParseStruct(string metadata, out MetadataStruct @struct)
        {
            @struct = new MetadataStruct();
            if (!Parse(metadata, _structRegex, out string typeName, out string typeBody)) return false;

            @struct.Name = typeName;
            MatchCollection collection = _structFieldRegex.Matches(typeBody);
            if (null == collection || collection.Count == 0) return false;

            int length = collection.Count;
            @struct.Fields = new MetadataField[length];
            for (int i = 0; i < length; i++)
            {
                var groups = collection[i].Groups;

                var fieldInfo = new MetadataField();
                fieldInfo.Name = groups[1].Value;
                fieldInfo.FieldType = groups[2].Value;
                fieldInfo.StructRepeated = !string.IsNullOrEmpty(groups[3].Value);

                @struct.Fields[i] = fieldInfo;
            }
            return true;
        }

        bool ParseEnum(string metadata, out MetadataStruct @struct)
        {
            @struct = new MetadataStruct();
            if (!Parse(metadata, _enumRegex, out string typeName, out string typeBody)) return false;

            @struct.Name = typeName;
            MatchCollection collection = _enumFieldRegex.Matches(typeBody);
            if (null == collection || collection.Count == 0) return false;

            int length = collection.Count;
            @struct.Fields = new MetadataField[length];
            for (int i = 0; i < length; i++)
            {
                var groups = collection[i].Groups;

                var fieldInfo = new MetadataField();
                fieldInfo.Name = groups[1].Value;
                var enumValue = groups[3].Value;
                fieldInfo.EnumValue = enumValue;
                var enumIntVal = 0;
                if (string.IsNullOrEmpty(enumValue) || int.TryParse(enumValue, out enumIntVal) == false)
                {
                    if (i == 0)
                    { // 
                        enumIntVal = 0;
                    }
                    else
                    { // 上一个枚举值加一
                        enumIntVal = @struct.Fields[i - 1].EnumIntVal + 1;
                    }
                }
                fieldInfo.EnumIntVal = enumIntVal;
                @struct.Fields[i] = fieldInfo;
            }
            return true;
        }
    }
}