using Microsoft.EntityFrameworkCore;

namespace timetracker.Data;

public class TimetrackerService(IDbContextFactory<TimetrackerDbContext> factory)
{
    public async Task<List<WorkDay>> GetWeekAsync(DateOnly monday)
    {
        await using var db = await factory.CreateDbContextAsync();
        return await db.WorkDays
            .Include(w => w.Breaks)
            .Where(w => w.Date >= monday && w.Date < monday.AddDays(7))
            .OrderBy(w => w.Date)
            .ToListAsync();
    }

    public async Task UpsertWorkDayAsync(WorkDay workDay)
    {
        await using var db = await factory.CreateDbContextAsync();
        var existing = await db.WorkDays
            .Include(w => w.Breaks)
            .FirstOrDefaultAsync(w => w.Date == workDay.Date);

        if (existing == null)
        {
            workDay.Id = 0;
            foreach (var b in workDay.Breaks) b.Id = 0;
            db.WorkDays.Add(workDay);
        }
        else
        {
            existing.StartTime = workDay.StartTime;
            existing.EndTime = workDay.EndTime;
            db.BreakEntries.RemoveRange(existing.Breaks);
            existing.Breaks.Clear();
            foreach (var b in workDay.Breaks)
                existing.Breaks.Add(new BreakEntry
                {
                    WorkDayId = existing.Id,
                    StartTime = b.StartTime,
                    EndTime = b.EndTime
                });
        }

        await db.SaveChangesAsync();
    }

    public async Task<AppSettings> GetSettingsAsync()
    {
        await using var db = await factory.CreateDbContextAsync();
        return await db.AppSettings.FindAsync(1) ?? new AppSettings { Id = 1 };
    }

    public async Task SaveSettingsAsync(AppSettings settings)
    {
        await using var db = await factory.CreateDbContextAsync();
        settings.Id = 1;
        var existing = await db.AppSettings.FindAsync(1);
        if (existing == null)
            db.AppSettings.Add(settings);
        else
        {
            existing.DailyTargetHours = settings.DailyTargetHours;
            existing.MinimumBreakMinutes = settings.MinimumBreakMinutes;
            existing.VacationDaysPerYear = settings.VacationDaysPerYear;
            existing.WorkMonday = settings.WorkMonday;
            existing.WorkTuesday = settings.WorkTuesday;
            existing.WorkWednesday = settings.WorkWednesday;
            existing.WorkThursday = settings.WorkThursday;
            existing.WorkFriday = settings.WorkFriday;
            existing.WorkSaturday = settings.WorkSaturday;
            existing.WorkSunday = settings.WorkSunday;
        }
        await db.SaveChangesAsync();
    }

    // ── Urlaub ────────────────────────────────────────────────────────────
    public async Task<List<VacationDay>> GetVacationDaysAsync(int year)
    {
        await using var db = await factory.CreateDbContextAsync();
        return await db.VacationDays
            .Where(v => v.Date.Year == year)
            .OrderBy(v => v.Date)
            .ToListAsync();
    }

    public async Task AddVacationDayAsync(VacationDay vacationDay)
    {
        await using var db = await factory.CreateDbContextAsync();
        var exists = await db.VacationDays.AnyAsync(v => v.Date == vacationDay.Date);
        if (!exists)
        {
            vacationDay.Id = 0;
            db.VacationDays.Add(vacationDay);
            await db.SaveChangesAsync();
        }
    }

    public async Task RemoveVacationDayAsync(int id)
    {
        await using var db = await factory.CreateDbContextAsync();
        var v = await db.VacationDays.FindAsync(id);
        if (v != null)
        {
            db.VacationDays.Remove(v);
            await db.SaveChangesAsync();
        }
    }

    // ── Gleitzeitkonto ───────────────────────────────────────────────────
    public async Task<TimeSpan> GetTotalOvertimeAsync(AppSettings settings)
    {
        await using var db = await factory.CreateDbContextAsync();
        var allDays = await db.WorkDays
            .Include(w => w.Breaks)
            .Where(w => w.StartTime != null && w.EndTime != null)
            .ToListAsync();

        var total = TimeSpan.Zero;
        foreach (var wd in allDays)
        {
            if (!settings.IsWorkDay(wd.Date.DayOfWeek)) continue;
            var gross = wd.EndTime!.Value.ToTimeSpan() - wd.StartTime!.Value.ToTimeSpan();
            if (gross <= TimeSpan.Zero) continue;
            var breakTotal = wd.Breaks
                .Where(b => b.StartTime.HasValue && b.EndTime.HasValue && b.EndTime > b.StartTime)
                .Aggregate(TimeSpan.Zero, (s, b) =>
                    s + (b.EndTime!.Value.ToTimeSpan() - b.StartTime!.Value.ToTimeSpan()));
            total += gross - breakTotal - TimeSpan.FromHours(settings.DailyTargetHours);
        }
        return total;
    }

    // ── Monatsübersicht ───────────────────────────────────────────────────
    public async Task<List<WorkDay>> GetMonthAsync(int year, int month)
    {
        await using var db = await factory.CreateDbContextAsync();
        var from = new DateOnly(year, month, 1);
        var to = from.AddMonths(1);
        return await db.WorkDays
            .Include(w => w.Breaks)
            .Where(w => w.Date >= from && w.Date < to)
            .OrderBy(w => w.Date)
            .ToListAsync();
    }
}