using LiteDB;
using LehrerApp.Core.Models;

namespace LehrerApp.Data;

/// <summary>
/// Zentrale LiteDB-Verbindung. Singleton – eine Datei = ein Nutzer.
/// </summary>
public class LiteDbContext : IDisposable
{
    private readonly LiteDatabase _db;

    public LiteDbContext(string databasePath)
    {
        _db = new LiteDatabase(new ConnectionString(databasePath)
        {
            Connection = ConnectionType.Shared,
        });
        MigrateExistingData();
        EnsureIndexes();
    }

    public ILiteCollection<Student>       Students      => _db.GetCollection<Student>("students");
    public ILiteCollection<LearningGroup> Groups        => _db.GetCollection<LearningGroup>("groups");
    public ILiteCollection<Enrollment>    Enrollments   => _db.GetCollection<Enrollment>("enrollments");
    public ILiteCollection<Exam>          Exams         => _db.GetCollection<Exam>("exams");
    public ILiteCollection<ExamResult>    ExamResults   => _db.GetCollection<ExamResult>("exam_results");
    public ILiteCollection<Grade>         Grades        => _db.GetCollection<Grade>("grades");
    public ILiteCollection<GradingKeyTemplate> GradingKeyTemplates => _db.GetCollection<GradingKeyTemplate>("grading_key_templates");
    public ILiteCollection<Unit>          Units         => _db.GetCollection<Unit>("units");
    public ILiteCollection<Lesson>        Lessons       => _db.GetCollection<Lesson>("lessons");
    public ILiteCollection<Documentation> Documentation => _db.GetCollection<Documentation>("documentation");
    public ILiteCollection<WorkTask>           Tasks              => _db.GetCollection<WorkTask>("tasks");
    public ILiteCollection<TimeEntry>          TimeEntries        => _db.GetCollection<TimeEntry>("time_entries");
    public ILiteCollection<ParticipationSession> ParticipationSessions => _db.GetCollection<ParticipationSession>("participation_sessions");
    public ILiteCollection<ParticipationEntry>   ParticipationEntries  => _db.GetCollection<ParticipationEntry>("participation");
    public ILiteCollection<ParticipationAspect>  ParticipationAspects  => _db.GetCollection<ParticipationAspect>("participation_aspects");
    public ILiteCollection<Subject>              Subjects              => _db.GetCollection<Subject>("subjects");
    public ILiteCollection<CompetencyDomain>     CompetencyDomains     => _db.GetCollection<CompetencyDomain>("competency_domains");

    public void Checkpoint() => _db.Checkpoint();

    private void MigrateExistingData()
    {
        var groups = _db.GetCollection<BsonDocument>("groups");
        var missingArchiveState = groups.FindAll()
            .Where(g => !g.ContainsKey(nameof(LearningGroup.IsActive)))
            .ToList();
        foreach (var group in missingArchiveState)
        {
            group[nameof(LearningGroup.IsActive)] = true;
            groups.Update(group);
        }
    }

    private void EnsureIndexes()
    {
        Students.EnsureIndex(x => x.LastName);
        Students.EnsureIndex(x => x.IsActive);
        Groups.EnsureIndex(x => x.SchoolYear);
        Groups.EnsureIndex(x => x.IsActive);
        Enrollments.EnsureIndex(x => x.StudentId);
        Enrollments.EnsureIndex(x => x.GroupId);
        Enrollments.EnsureIndex(x => x.SchoolYear);
        Exams.EnsureIndex(x => x.GroupId);
        Exams.EnsureIndex(x => x.Status);
        ExamResults.EnsureIndex(x => x.ExamId);
        ExamResults.EnsureIndex(x => x.StudentId);
        Grades.EnsureIndex(x => x.StudentId);
        Grades.EnsureIndex(x => x.GroupId);
        GradingKeyTemplates.EnsureIndex(x => x.GradingSystem);
        Units.EnsureIndex(x => x.GroupId);
        Lessons.EnsureIndex(x => x.UnitId);
        Lessons.EnsureIndex(x => x.GroupId);
        Lessons.EnsureIndex(x => x.Date);
        Documentation.EnsureIndex(x => x.StudentId);
        Tasks.EnsureIndex(x => x.Status);
        TimeEntries.EnsureIndex(x => x.Date);
        ParticipationSessions.EnsureIndex(x => x.GroupId);
        ParticipationSessions.EnsureIndex(x => x.Date);
        ParticipationEntries.EnsureIndex(x => x.SessionId);
        ParticipationEntries.EnsureIndex(x => x.StudentId);
        ParticipationAspects.EnsureIndex(x => x.GroupId);
        Subjects.EnsureIndex(x => x.Name);
        CompetencyDomains.EnsureIndex(x => x.SubjectId);
        CompetencyDomains.EnsureIndex(x => x.GradeLevel);
    }

    public void Dispose() => _db.Dispose();
}