using System;
using System.Collections.Generic;
using System.Linq;
using Centron.BusinessLogic;
using Centron.BusinessLogic.Sales.CustomerAssets.TimerBilling;
using Centron.BusinessLogic.WebServices.Employee;
using Centron.Interfaces.BL;
using Centron.Tests.EndToEnd.Infrastructure;
using CentronSoftware.Centron.WebServices.Entities.Sales.CustomerAssets.TimerBilling;
using Xunit.Abstractions;

namespace Centron.Tests.EndToEnd.Tests.Administration.Employees;

/// <summary>
/// Regression tests for ticket 168634.
/// Deactivating an employee used to delete the employee-article assignment (Mitarbeiterartikel).
/// That assignment is the only link between a recorded time and its employee in the billing modules,
/// so the deactivation silently made all already recorded times of that employee unbillable - and a
/// reactivation could not restore it.
/// These tests cover both halves of the fix: the assignment now survives a deactivation (only the
/// articles are marked as end-of-life), and the billing search falls back to the employee who
/// recorded the time when the assignment is missing.
/// </summary>
public class EmployeeDeactivationBillingTests : EndToEndTest
{
    public EmployeeDeactivationBillingTests(ITestOutputHelper testOutputHelper)
        : base(testOutputHelper)
    {
    }

    public override void Execute()
    {
        var appUserI3D = this.GetAppUserWithBillableTimers();
        var employeeI3D = this.Sql<int>($"SELECT Personal FROM dbo.Sichbenu WHERE I3D = {appUserI3D}");

        this.DeactivationKeepsAssignmentAndMarksArticlesEndOfLife(appUserI3D);
        this.ReactivationRevokesEndOfLife(appUserI3D);
        this.TimersStayAttributedWhenAssignmentIsMissing(appUserI3D, employeeI3D);
    }

    /// <summary>
    /// Finds an app-user that has employee articles which are used by open (not yet billed) timers
    /// recorded by that same employee.
    /// </summary>
    private int GetAppUserWithBillableTimers()
    {
        var appUserI3D = this.Sql<int>(@"
SELECT TOP 1 SB.I3D
FROM dbo.hlpdsk_timer HT
INNER JOIN dbo.Mitarbeiterartikel MA ON MA.ArtikelI3D = HT.ArtikelI3D
INNER JOIN dbo.Sichbenu SB ON SB.I3D = MA.MitarbeiterI3D
WHERE ISNULL(HT.RechPosI3D, 0) = 0
  AND ISNULL(HT.LiefPosI3D, 0) = 0
  AND ISNULL(HT.AufPosI3D, 0) = 0
  AND HT.PersonalI3D = SB.Personal
GROUP BY SB.I3D
ORDER BY COUNT(*) DESC, SB.I3D");

        if (appUserI3D <= 0)
            throw new InvalidOperationException("No app-user with employee articles and open timers found in the test database.");

        return appUserI3D;
    }

    /// <summary>
    /// Deactivating an employee must keep the employee-article assignment and only mark the
    /// assigned articles as end-of-life, so the articles disappear from new selections while
    /// the recorded times stay attributable.
    /// </summary>
    private void DeactivationKeepsAssignmentAndMarksArticlesEndOfLife(int appUserI3D)
    {
        // Reset the end-of-life flag first, so the snapshot is independent of the backup's state.
        this.Sql($@"
UPDATE A SET A.EOL = 0
FROM dbo.ARTIK A
INNER JOIN dbo.Mitarbeiterartikel MA ON MA.ArtikelI3D = A.I3D
WHERE MA.MitarbeiterI3D = {appUserI3D}");

        this.SetEmployeeArticlesEndOfLife(appUserI3D, true);

        this.VerifyEmployeeArticles("Deactivation_AssignmentKeptAndArticlesEndOfLife", appUserI3D);
    }

    /// <summary>
    /// Reactivating an employee must revoke the end-of-life mark that the deactivation has set.
    /// </summary>
    private void ReactivationRevokesEndOfLife(int appUserI3D)
    {
        this.SetEmployeeArticlesEndOfLife(appUserI3D, false);

        this.VerifyEmployeeArticles("Reactivation_ArticlesUsableAgain", appUserI3D);
    }

    /// <summary>
    /// Databases that were damaged by the old deactivation behaviour have no employee-article
    /// assignment left. The billing search must still attribute those times to the employee who
    /// recorded them, otherwise the times can never be billed again.
    /// Times that merely use one of the employee's articles but were recorded by somebody else
    /// move to that other employee, which is the correct attribution once the assignment is gone.
    /// </summary>
    private void TimersStayAttributedWhenAssignmentIsMissing(int appUserI3D, int employeeI3D)
    {
        var timersBefore = this.SearchTimersForEmployee(employeeI3D);

        if (timersBefore.Any() == false)
            throw new InvalidOperationException($"No open timers found for employee {employeeI3D} in the test database.");

        // Simulate a database that was damaged by the old deactivation behaviour.
        this.Sql($"DELETE FROM dbo.Mitarbeiterartikel WHERE MitarbeiterI3D = {appUserI3D}");

        var timersAfter = this.SearchTimersForEmployee(employeeI3D);

        this.Verifier.Verify("TimerBillingSearch_WithoutEmployeeArticleAssignment", new
        {
            AssignmentsLeft = this.Sql<int>($"SELECT COUNT(*) FROM dbo.Mitarbeiterartikel WHERE MitarbeiterI3D = {appUserI3D}"),
            TimersFoundBefore = timersBefore.Count,
            TimersRecordedByEmployeeBefore = timersBefore.Count(timer => timer.CreatorEmployeeI3D == employeeI3D),
            TimersFoundAfter = timersAfter.Count,
            TimersRecordedByEmployeeAfter = timersAfter.Count(timer => timer.CreatorEmployeeI3D == employeeI3D)
        });
    }

    private void SetEmployeeArticlesEndOfLife(int appUserI3D, bool isEndOfLife)
    {
        using (var session = new BLSession())
        {
            session.GetBL<EmployeeArticleWebServiceBL>()
                .SetEmployeeArticlesEndOfLife(this.GetLoggedInUser(), appUserI3D, isEndOfLife)
                .ThrowIfError();
        }
    }

    private void VerifyEmployeeArticles(string name, int appUserI3D)
    {
        this.Verifier.VerifySql(name, $@"
SELECT ArticleCode = A.Artikelcode,
       IsEndOfLife = CAST(ISNULL(A.EOL, 0) AS bit)
FROM dbo.Mitarbeiterartikel MA
INNER JOIN dbo.ARTIK A ON A.I3D = MA.ArtikelI3D
WHERE MA.MitarbeiterI3D = {appUserI3D}
ORDER BY A.Artikelcode");
    }

    private List<TimerForTimerBillingDTO> SearchTimersForEmployee(int employeeI3D)
    {
        using (var session = new BLSession())
        {
            return session.GetBL<TimerBillingBL>()
                .SearchTimers(new TimerBillingFilter { EmployeeI3Ds = new List<int> { employeeI3D } })
                .ToList();
        }
    }
}