using Distribution.Data;
using Microsoft.EntityFrameworkCore;

namespace Distribution.Features.Notifications;

public class NotificationRepository(AppDBContext context) : INotificationRepository
{
    // ── Inbox ────────────────────────────────────────────────────────────

    public async Task AddAsync(Models.Notification notification) =>
        await context.Notifications.AddAsync(notification);

    public void Discard(Models.Notification notification)
    {
        foreach (var recipient in notification.Recipients)
            context.Entry(recipient).State = EntityState.Detached;
        context.Entry(notification).State = EntityState.Detached;
    }

    private IQueryable<Models.NotificationRecipient> InboxQuery(Guid userId, bool unreadOnly)
    {
        var query = context.NotificationRecipients.Where(r => r.FK_UserId == userId && r.IsActive);
        return unreadOnly ? query.Where(r => !r.IsRead) : query;
    }

    public Task<int> GetInboxCountAsync(Guid userId, bool unreadOnly) =>
        InboxQuery(userId, unreadOnly).CountAsync();

    public Task<List<Models.NotificationRecipient>> GetInboxAsync(Guid userId, bool unreadOnly, int page, int pageSize) =>
        InboxQuery(userId, unreadOnly)
            .Include(r => r.Notification)
            .OrderByDescending(r => r.Notification.CreatedAt)
            .Skip((page - 1) * pageSize)
            .Take(pageSize)
            .AsNoTracking()
            .ToListAsync();

    public Task<int> GetUnreadCountAsync(Guid userId) =>
        InboxQuery(userId, unreadOnly: true).CountAsync();

    public Task<Models.NotificationRecipient?> GetRecipientAsync(Guid userId, Guid recipientId) =>
        context.NotificationRecipients
            .FirstOrDefaultAsync(r => r.Id == recipientId && r.FK_UserId == userId && r.IsActive);

    public Task<List<Models.NotificationRecipient>> GetUnreadRecipientsAsync(Guid userId) =>
        InboxQuery(userId, unreadOnly: true).ToListAsync();

    public void RemoveRecipient(Models.NotificationRecipient recipient) =>
        context.NotificationRecipients.Remove(recipient);

    // ── Recipient resolution ─────────────────────────────────────────────

    public Task<List<Guid>> FilterActiveUserIdsAsync(IEnumerable<Guid> userIds)
    {
        var ids = userIds.ToList();
        return context.Users
            .Where(u => u.IsActive && ids.Contains(u.Id))
            .Select(u => u.Id)
            .ToListAsync();
    }

    public Task<List<Guid>> GetUserIdsByPermissionAsync(string permissionCode) =>
        context.Users
            .Where(u => u.IsActive && context.RolePermissions.Any(rp =>
                rp.FK_RoleId == u.FK_RoleId && rp.IsActive &&
                rp.Permission.IsActive && rp.Permission.Code == permissionCode))
            .Select(u => u.Id)
            .ToListAsync();

    public async Task<List<Guid>> GetUserIdsByScopeAsync(ScopeKind kind, Guid id)
    {
        Guid? regionId = null;
        Guid? routeId = null;
        Guid? storeId = null;

        switch (kind)
        {
            case ScopeKind.Region:
                regionId = id;
                break;
            case ScopeKind.Route:
                routeId = id;
                regionId = await context.Routes.Where(r => r.Id == id)
                    .Select(r => (Guid?)r.FK_RegionId).FirstOrDefaultAsync();
                break;
            case ScopeKind.Store:
                storeId = id;
                routeId = await context.Stores.Where(s => s.Id == id)
                    .Select(s => (Guid?)s.FK_RouteId).FirstOrDefaultAsync();
                if (routeId is { } rid)
                    regionId = await context.Routes.Where(r => r.Id == rid)
                        .Select(r => (Guid?)r.FK_RegionId).FirstOrDefaultAsync();
                break;
        }

        var userIds = new HashSet<Guid>();

        if (regionId is { } region)
            userIds.UnionWith(await context.UserRegionScopes
                .Where(s => s.IsActive && s.FK_RegionId == region)
                .Select(s => s.FK_UserId).ToListAsync());

        if (routeId is { } route)
            userIds.UnionWith(await context.UserRouteScopes
                .Where(s => s.IsActive && s.FK_RouteId == route)
                .Select(s => s.FK_UserId).ToListAsync());

        if (storeId is { } store)
            userIds.UnionWith(await context.UserStoreScopes
                .Where(s => s.IsActive && s.FK_StoreId == store)
                .Select(s => s.FK_UserId).ToListAsync());

        return userIds.ToList();
    }

    public Task<Guid?> GetReportsToUserIdAsync(Guid userId) =>
        context.Users.Where(u => u.Id == userId)
            .Select(u => u.FK_ReportsToUserId)
            .FirstOrDefaultAsync();

    public async Task<Guid?> GetRouteOwnerUserIdAsync(ScopeKind kind, Guid id)
    {
        Guid? routeId = kind switch
        {
            ScopeKind.Route => id,
            ScopeKind.Store => await context.Stores.Where(s => s.Id == id)
                .Select(s => (Guid?)s.FK_RouteId).FirstOrDefaultAsync(),
            _ => null
        };
        if (routeId is not { } rid) return null;

        return await context.Routes.Where(r => r.Id == rid && r.IsActive)
            .Select(r => r.FK_OwnerUserId)
            .FirstOrDefaultAsync();
    }

    // ── Retention ────────────────────────────────────────────────────────

    public Task<List<Models.NotificationRecipient>> GetExpiredReadRecipientsAsync(DateTime cutoff, int take) =>
        context.NotificationRecipients
            .Where(r => r.IsRead && r.ReadAt != null && r.ReadAt < cutoff)
            .Take(take)
            .ToListAsync();

    public Task<List<Models.Notification>> GetOrphanNotificationsAsync(int take) =>
        context.Notifications
            .Where(n => !n.Recipients.Any())
            .Take(take)
            .ToListAsync();

    public void RemoveRecipients(IEnumerable<Models.NotificationRecipient> recipients) =>
        context.NotificationRecipients.RemoveRange(recipients);

    public void RemoveNotifications(IEnumerable<Models.Notification> notifications) =>
        context.Notifications.RemoveRange(notifications);
}