using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using QMax.Api.Data;
using QMax.Api.Data.Entities;
using QMax.Api.Infrastructure.Auth;

namespace QMax.Api.Controllers;

[ApiController]
[Authorize]
[Route("api/push")]
public sealed class PushController(QMaxDbContext db, ILogger<PushController> logger) : ControllerBase
{
    public sealed record RegisterPushDeviceRequest(string FirebaseToken, string Platform);

    [HttpPost("devices")]
    public async Task<IActionResult> Register(RegisterPushDeviceRequest request, CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(request.FirebaseToken))
        {
            return BadRequest("firebaseToken is required.");
        }

        var userId = await ResolvePushUserIdAsync(User.GetUserId(), cancellationToken);
        if (userId is null)
        {
            return Unauthorized();
        }

        var device = await db.PushDevices.FirstOrDefaultAsync(x => x.FirebaseToken == request.FirebaseToken, cancellationToken);
        if (device is null)
        {
            device = new PushDevice { FirebaseToken = request.FirebaseToken };
            db.PushDevices.Add(device);
        }

        device.UserId = userId.Value;
        device.Platform = string.IsNullOrWhiteSpace(request.Platform) ? "android" : request.Platform;
        device.UpdatedAt = DateTimeOffset.UtcNow;
        await db.SaveChangesAsync(cancellationToken);
        return NoContent();
    }

    [HttpDelete("devices/{id:guid}")]
    public async Task<IActionResult> Delete(Guid id, CancellationToken cancellationToken)
    {
        var userId = User.GetUserId();
        var device = await db.PushDevices.FirstOrDefaultAsync(x => x.Id == id && x.UserId == userId, cancellationToken);
        if (device is null)
        {
            return NotFound();
        }

        db.PushDevices.Remove(device);
        await db.SaveChangesAsync(cancellationToken);
        return NoContent();
    }

    private async Task<Guid?> ResolvePushUserIdAsync(Guid authenticatedUserId, CancellationToken cancellationToken)
    {
        if (await db.Users.AnyAsync(x => x.Id == authenticatedUserId, cancellationToken))
        {
            return authenticatedUserId;
        }

        var existingUserIds = await db.Users
            .Select(x => x.Id)
            .Take(2)
            .ToArrayAsync(cancellationToken);

        if (existingUserIds.Length == 1)
        {
            logger.LogWarning(
                "Push registration used stale user {AuthenticatedUserId}; attaching device to single existing user {UserId}.",
                authenticatedUserId,
                existingUserIds[0]);
            return existingUserIds[0];
        }

        if (existingUserIds.Length > 1)
        {
            logger.LogWarning(
                "Push registration used missing user {AuthenticatedUserId}, but database has multiple users.",
                authenticatedUserId);
            return null;
        }

        db.Users.Add(new User
        {
            Id = authenticatedUserId,
            DisplayName = User.Identity?.Name?.Trim() is { Length: > 0 } displayName
                ? displayName
                : "QMAX Owner"
        });
        return authenticatedUserId;
    }
}