using System;
using System.Collections.Generic;
using System.Data;
using System.IO;

namespace etoy
{
    //  KeyValue表结构
    // *   0                    1                   2                   3                   4
    // 0  key                 value               type            description              tag
    // 1  AAA                   0                 int                des1                   c
    // 2  BBB                  111                int                des2
    // 3  CCC                 Hello              string              des3                   s
    // 4  DDD                 <Json>             string              des4

    //  * type 目前仅支持 int & string

    sealed class KeyValueTableCsvParser
    {
        const int START_ROW = 1;

        public KeyValueTable Parse(DataTable dt, string file)
        {
            int rowCount = dt.Rows.Count;
            int colCount = dt.Columns.Count;
            if (rowCount <= 0 || colCount < 5)
                throw new Exception($"KeyValue表结构不合法, Row: {rowCount}, Column: {colCount}");

            var row0 = dt.Rows[0];
            string key = row0[0].ToString().ToFieldType();
            string value = row0[1].ToString().ToFieldType();
            string type = row0[2].ToString().ToFieldType();
            string description = row0[3].ToString().ToFieldType();
            string tag = row0[4].ToString().ToFieldType();

            if (key != nameof(key) ||
                value != nameof(value) ||
                type != nameof(type) ||
                description != nameof(description) ||
                tag != nameof(tag))
                throw new Exception();

            var rows = new List<KeyValueRow>(rowCount);
            for (int i = START_ROW; i < rowCount; ++i)
            {
                var row = dt.Rows[i];
                if (string.IsNullOrEmpty(row[0] as string)) // key为empty，不处理此行
                    continue;

                var keyValueRow = new KeyValueRow();
                keyValueRow.Row = i;
                for (int j = 0; j < colCount; ++j)
                {
                    var cellvalue = row[j].ToString().ToCellValue();
                    var keyValueType = (KeyValueColumn)j;
                    switch (keyValueType)
                    {
                        case KeyValueColumn.Key:
                            keyValueRow.Key = cellvalue;
                            break;

                        case KeyValueColumn.Value:
                            keyValueRow.Value = cellvalue;
                            break;

                        case KeyValueColumn.Type:
                            keyValueRow.Type = cellvalue;
                            break;

                        case KeyValueColumn.Description:
                            keyValueRow.Description = cellvalue;
                            break;

                        case KeyValueColumn.Tag:
                            keyValueRow.Tag = cellvalue?.ToLower() ?? string.Empty;
                            break;

                        default:
                            throw new Exception();
                    }
                }

                rows.Add(keyValueRow);
            }

            var table = new KeyValueTable();
            table.Name = Path.GetFileNameWithoutExtension(file).ToTableName();
            table.Path = file;
            table.Rows = rows.ToArray();

            return table;
        }
    }
}