using ECMJobRunner.Application.Common.Constants;
using ECMJobRunner.Application.Common.Dtos;
using ECMJobRunner.Application.Common.Exceptions;
using ECMJobRunner.Domain.Interfaces;
using ECMJobRunner.Application.Common.Options;
using ECMJobRunner.Application.DEXJob;
using MediatR;
using Microsoft.Extensions.Options;
using System;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;

namespace ECMJobRunner.Application.Behaviors
{
    /// <summary>
    /// Pipeline behavior that executes the main SQL query for DEX jobs
    /// Runs before the command handler and validates query results
    /// </summary>
    /// <typeparam name="TRequest">The request type</typeparam>
    /// <typeparam name="TResponse">The response type</typeparam>
    public class MainQueryExecutionBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
        where TRequest : notnull
    {
        private readonly ISQLExecutor _executor;
        private readonly DexJobOptions _options;

        /// <summary>
        /// Initializes a new instance of MainQueryExecutionBehavior
        /// </summary>
        /// <param name="executor">SQL executor for query execution</param>
        /// <param name="options">DEX job configuration options</param>
        public MainQueryExecutionBehavior(ISQLExecutor executor, IOptions<DexJobOptions> options)
        {
            _executor = executor;
            _options = options.Value;
        }

        /// <summary>
        /// Handles the pipeline behavior
        /// Executes main query if request is TriggeringDEXJobCommand
        /// </summary>
#if NET48
        public async Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate<TResponse> next)
#else
        public async Task<TResponse> Handle(TRequest request, RequestHandlerDelegate<TResponse> next, CancellationToken cancellationToken)
#endif
        {
            if (request is TriggeringDEXJobCommand command)
            {
                await ExecuteMainQueryAsync(command, cancellationToken);
            }

            return await next();
        }

        private async Task ExecuteMainQueryAsync(TriggeringDEXJobCommand command, CancellationToken cancel)
        {
            if (!string.IsNullOrWhiteSpace(command.Job.SqlMainQuery))
            {
                var sqlMainQuery = Regex.Replace(
                    command.Job.SqlMainQuery!,
                    _options.Placeholders.BatchId.Pattern,
                    command.BatchId,
                    _options.Placeholders.BatchId.RegexOptions);

                try
                {
                    var result = await _executor.ExecuteQueryAsync<MainQueryResult>(sqlMainQuery, cancel);
                    if (_options.Error.MainQuery.OnUnexpectedResult == ErrorAction.Stop)
                    {
                        if (result is null)
                            throw new JobSqlException(
                                jobName: "Triggering DEX",
                                processName: "Main Query",
                                batchId: command.BatchId,
                                reason: "Main Query returned nothing.",
                                query: sqlMainQuery,
                                innerException: null);
                        else if (result.ReturnValue is not null)
                            throw new JobSqlException(
                                jobName: "Triggering DEX",
                                processName: "Main Query",
                                batchId: command.BatchId,
                                reason: $"The query unexpectedly returned the value {result.ReturnValue}. The expected value was null.",
                                query: sqlMainQuery, innerException: null);
                    }
                }
                catch (Exception ex)
                {
                    if (_options.Error.MainQuery.OnExecution == ErrorAction.Stop)
                        throw new JobSqlException(
                            jobName: "Triggering DEX",
                            processName: "Main Query",
                            batchId: command.BatchId,
                            reason: null,
                            query: sqlMainQuery,
                            innerException: ex);
                }
            }
            else if (_options.Error.MainQuery.IfNullOrWhiteSpace == ErrorAction.Stop)
            {
                throw new JobSqlException(
                    jobName: "Triggering DEX",
                    processName: "Main Query",
                    batchId: command.BatchId,
                    reason: "SQL Check Query is null or empty",
                    query: null,
                    innerException: null);
            }
        }
    }
}