using System.Security.Claims;
using Jiaowu.Api.Domain.Academic;
using Jiaowu.Api.Domain.Identity;
using Jiaowu.Api.Infrastructure.Auth;
using Jiaowu.Api.Infrastructure.Persistence;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace Jiaowu.Api.Controllers;

[ApiController]
[Authorize]
[Route("api/notifications")]
public sealed class NotificationsController(
    AppDbContext db,
    ICurrentUserDataScope currentUserDataScope) : ControllerBase
{
    [HttpGet]
    public async Task<ActionResult> GetNotifications(
        bool? unreadOnly,
        int page = 1,
        int pageSize = 20,
        CancellationToken cancellationToken = default)
    {
        var userId = currentUserDataScope.Current.UserId;
        var source = db.Notifications.AsNoTracking()
            .Where(x => x.UserId == userId);
        if (unreadOnly == true)
            source = source.Where(x => !x.IsRead);

        var total = await source.CountAsync(cancellationToken);
        var items = await source
            .OrderByDescending(x => x.CreatedAt)
            .Skip((page - 1) * pageSize)
            .Take(pageSize)
            .Select(x => new
            {
                x.Id, x.Title, x.Content, x.IsRead, x.LinkUrl, x.CreatedAt
            })
            .ToListAsync(cancellationToken);

        var unreadCount = await db.Notifications
            .CountAsync(x => x.UserId == userId && !x.IsRead, cancellationToken);

        return Ok(new { Items = items, Total = total, UnreadCount = unreadCount });
    }

    [HttpGet("unread-count")]
    public async Task<ActionResult> GetUnreadCount(CancellationToken cancellationToken)
    {
        var userId = currentUserDataScope.Current.UserId;
        var count = await db.Notifications
            .CountAsync(x => x.UserId == userId && !x.IsRead, cancellationToken);
        return Ok(new { Count = count });
    }

    [HttpPost("{id:guid}/read")]
    public async Task<ActionResult> MarkRead(Guid id, CancellationToken cancellationToken)
    {
        var userId = currentUserDataScope.Current.UserId;
        var n = await db.Notifications
            .FirstOrDefaultAsync(x => x.Id == id && x.UserId == userId, cancellationToken);
        if (n is null) return NotFound();
        n.IsRead = true;
        await db.SaveChangesAsync(cancellationToken);
        return NoContent();
    }

    [HttpPost("read-all")]
    public async Task<ActionResult> MarkAllRead(CancellationToken cancellationToken)
    {
        var userId = currentUserDataScope.Current.UserId;
        await db.Notifications
            .Where(x => x.UserId == userId && !x.IsRead)
            .ExecuteUpdateAsync(s => s.SetProperty(x => x.IsRead, true),
                cancellationToken);
        return NoContent();
    }
}

/// <summary>
/// Centralized helper to send notifications across the app.
/// </summary>
public static class NotificationService
{
    public static async Task SendAsync(
        AppDbContext db,
        Guid userId,
        string title,
        string content,
        string? linkUrl = null,
        CancellationToken cancellationToken = default)
    {
        db.Notifications.Add(new Notification
        {
            UserId = userId,
            Title = title,
            Content = content,
            LinkUrl = linkUrl
        });
        await db.SaveChangesAsync(cancellationToken);
    }

    public static async Task SendToRoleAsync(
        AppDbContext db,
        string roleName,
        string title,
        string content,
        Guid? collegeId = null,
        string? linkUrl = null,
        CancellationToken cancellationToken = default)
    {
        var query = db.Users
            .Join(db.UserRoles, u => u.Id, ur => ur.UserId, (u, ur) => new { u.Id, ur.RoleId })
            .Join(db.Roles, x => x.RoleId, r => r.Id, (x, r) => new { x.Id, RoleName = r.Name! });

        var userIds = query.Where(x => x.RoleName == roleName);

        if (collegeId.HasValue && roleName == SystemRoles.CollegeAdmin)
        {
            userIds = userIds.Where(x =>
                db.Teachers.Any(t =>
                    t.UserId == x.Id && t.CollegeId == collegeId.Value));
        }

        var ids = await userIds.Select(x => x.Id).Distinct().ToListAsync(cancellationToken);
        foreach (var id in ids)
        {
            db.Notifications.Add(new Notification
            {
                UserId = id,
                Title = title,
                Content = content,
                LinkUrl = linkUrl
            });
        }
        await db.SaveChangesAsync(cancellationToken);
    }

    public static async Task SendToUserIdsAsync(
        AppDbContext db,
        IEnumerable<Guid> userIds,
        string title,
        string content,
        string? linkUrl = null,
        CancellationToken cancellationToken = default)
    {
        foreach (var userId in userIds.Distinct())
        {
            db.Notifications.Add(new Notification
            {
                UserId = userId,
                Title = title,
                Content = content,
                LinkUrl = linkUrl
            });
        }
        await db.SaveChangesAsync(cancellationToken);
    }
}