using System.Data;
using Validation.Core;

namespace Validation.Rule.Format
{
    /// <summary>
    /// 邮箱格式校验规则
    /// </summary>
    public class EmailValidationRule : IValidationRule
    {
        private readonly string columnName;

        public string RuleName => $"Email_{columnName}";
        public string Description => $"检查列'{columnName}'的邮箱格式";

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="columnName">要校验的列</param>
        public EmailValidationRule(string columnName)
        {
            this.columnName = columnName;
        }

        /// <inheritdoc />
        public ValidationResult Validate(DataTable dataTable)
        {
            var result = new ValidationResult { IsValid = true };

            if (!dataTable.Columns.Contains(columnName))
                return result;

            foreach (DataRow row in dataTable.Rows)
            {
                int rowIndex = dataTable.Rows.IndexOf(row);

                if (!row.IsNull(columnName))
                {
                    var value = row[columnName]?.ToString() ?? string.Empty;
                    if (!IsValidEmail(value))
                    {
                        result.AddError(rowIndex, $"第{rowIndex + 1}行，列'{columnName}'的邮箱格式不正确: {value}");
                    }
                }
            }

            return result;
        }

        /// <inheritdoc />
        public ValidationResult Validate(string[] headers, int rowIndex, object[] values)
        {
            var result = new ValidationResult { IsValid = true };

            // 查找列索引
            int columnIndex = Array.IndexOf(headers, columnName);

            // 如果找不到列或值为空，则直接返回
            if (columnIndex < 0 || columnIndex >= values.Length || values[columnIndex] == null || values[columnIndex] == DBNull.Value)
            {
                return result;
            }

            var value = values[columnIndex]?.ToString() ?? string.Empty;
            if (!IsValidEmail(value))
            {
                result.AddError(rowIndex, $"第{rowIndex + 1}行，列'{columnName}'的邮箱格式不正确: {value}");
            }

            return result;
        }

        private bool IsValidEmail(string email)
        {
            return !string.IsNullOrEmpty(email) &&
                   email.Contains("@") &&
                   email.Contains(".") &&
                   email.IndexOf('@') < email.LastIndexOf('.');
        }
    }
}