using ClosedXML.Excel;
using SurveyLib.Core.Services;
using SurveyLib.Core.Tools;

namespace SurveyLib.Tools.Tools;

public class TableExporter : IDataExporter
{
    private readonly ISurveyService _surveyService;
    private readonly IQuestionService _questionService;
    private readonly ICompletionService _completionService;
    private readonly IAnswerService _answerService;

    public TableExporter(ISurveyService surveyService, IQuestionService questionService,
        ICompletionService completionService, IAnswerService answerService)
    {
        _surveyService = surveyService;
        _questionService = questionService;
        _completionService = completionService;
        _answerService = answerService;
    }

    public async Task<byte[]> ExportDataBySurveyIdAsync(int surveyId)
    {
        var survey = await _surveyService.GetSurveyAsync(surveyId);
        var questions = await _questionService.GetQuestionsBySurveyIdAsync(surveyId);
        var completions = await _completionService.GetCompletionsBySurveyIdAsync(surveyId);

        using var workbook = new XLWorkbook();
        var ws = workbook.Worksheets.Add(survey.Title);
        ws.Cell(1, 1).Value = "Title";
        ws.Cell(1, 2).Value = survey.Title;

        ws.Cell(2, 1).Value = "Description";
        ws.Cell(2, 2).Value = survey.Description;

        ws.Cell(3, 1).Value = "Export issued at";
        ws.Cell(3, 2).Value = DateTime.UtcNow;

        ws.Cell(4, 1).Value = "Completed By";
        ws.Cell(4, 2).Value = "Finished At";

        var column = 3;
        foreach (var question in questions)
        {
            ws.Cell(4, column).Value = question.Title;
            column++;
        }

        var row = 5;
        foreach (var completion in completions)
        {
            ws.Cell(row, 1).Value = completion.CompletedBy?.ToString() ?? "Unknown";
            ws.Cell(row, 2).Value = completion.FinishedAt;
            column = 3;
            var answers = await _answerService.GetAnswersByCompletionIdAsync(completion.Id);
            var answersGroupedByQuestion = answers.GroupBy(a => a.QuestionId);
            foreach (var questionAnswers in answersGroupedByQuestion)
            {
                ws.Cell(row, column).Value = string.Join("; ", questionAnswers.Select(a => a.AnswerText));
                column++;
            }

            row++;
        }

        ws.Columns().AdjustToContents();

        using var stream = new MemoryStream();
        workbook.SaveAs(stream);
        return stream.ToArray();
    }
}