using System.Threading.Channels;
using Validation.Core;

namespace Validation.Validator
{
    /// <summary>
    /// CSV数据校验类，使用Channel提升并发效率
    /// </summary>
    public class CsvDataValidator
    {
        private readonly SimpleDataValidator validator;
        private readonly Channel<string[]> channel;
        private readonly List<IValidationRule> rules;

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="validator">数据校验器</param>
        /// <param name="rules">校验规则列表</param>
        public CsvDataValidator(SimpleDataValidator validator, List<IValidationRule> rules)
        {
            this.validator = validator;
            this.rules = rules;
            
            // 创建一个有界通道，用于控制内存使用
            var options = new BoundedChannelOptions(100)
            {
                FullMode = BoundedChannelFullMode.Wait
            };
            channel = Channel.CreateBounded<string[]>(options);
        }

        /// <summary>
        /// 读取CSV文件并发送数据到通道
        /// </summary>
        /// <param name="filePath">CSV文件路径</param>
        /// <param name="cancellationToken">取消令牌</param>
        /// <returns>表示异步操作的任务</returns>
        public async Task ReadCsvFileAsync(string filePath, CancellationToken cancellationToken = default)
        {
            var writer = channel.Writer;
            
            try
            {
                using (var reader = new StreamReader(filePath))
                {
                    string? line;
                    bool isFirstLine = true;
                    
                    while ((line = await reader.ReadLineAsync(cancellationToken)) != null && !cancellationToken.IsCancellationRequested)
                    {
                        if (isFirstLine)
                        {
                            // 第一行作为标题行处理
                            isFirstLine = false;
                            continue;
                        }
                        
                        var values = ParseCsvLine(line);
                        await writer.WriteAsync(values, cancellationToken);
                    }
                }
            }
            finally
            {
                writer.Complete();
            }
        }

        /// <summary>
        /// 处理通道中的数据并进行校验
        /// </summary>
        /// <param name="headers">CSV标题行</param>
        /// <param name="cancellationToken">取消令牌</param>
        /// <returns>校验结果</returns>
        public async Task<ValidationResult> ProcessDataAsync(string[] headers, CancellationToken cancellationToken = default)
        {
            var reader = channel.Reader;
            var result = new ValidationResult { IsValid = true };

            // 创建多个消费者任务来处理数据
            var consumerTasks = new List<Task>();
            for (int i = 0; i < Environment.ProcessorCount; i++)
            {
                consumerTasks.Add(ProcessDataConsumerAsync(headers, result, cancellationToken));
            }

            // 等待所有消费者任务完成
            await Task.WhenAll(consumerTasks);
            return result;
        }

        /// <summary>
        /// 数据消费者任务
        /// </summary>
        /// <param name="headers">CSV标题行</param>
        /// <param name="result">校验结果</param>
        /// <param name="cancellationToken">取消令牌</param>
        /// <returns>表示异步操作的任务</returns>
        private async Task ProcessDataConsumerAsync(string[] headers, ValidationResult result, CancellationToken cancellationToken)
        {
            var reader = channel.Reader;
            int rowIndex = 1; // 每个消费者从第二行开始（第一行是标题）
            
            await foreach (var values in reader.ReadAllAsync(cancellationToken))
            {
                var rowResult = validator.Validate(headers, rowIndex, values, rules);
                
                lock (result)
                {
                    if (!rowResult.IsValid)
                    {
                        result.IsValid = false;
                        result.Errors.AddRange(rowResult.Errors);
                    }
                    result.Warnings.AddRange(rowResult.Warnings);
                }
                
                rowIndex++;
            }
        }

        /// <summary>
        /// 简单的CSV行解析方法（实际项目中可能需要更复杂的处理）
        /// </summary>
        /// <param name="line">CSV行数据</param>
        /// <returns>解析后的字符串数组</returns>
        private string[] ParseCsvLine(string line)
        {
            return line.Split(',');
        }
    }
}