using HrynCo.NotificationService.DAL.Abstract.PushChannels;
using HrynCo.NotificationService.DAL.EF.Entities;
using Microsoft.EntityFrameworkCore;

namespace HrynCo.NotificationService.DAL.EF.Repositories;

internal sealed class PushChannelRepository(NotificationDbContext db, TemplateMutationRunner mutations) : IPushChannelRepository
{
    public async Task<IReadOnlyList<PushChannel>> GetAllAsync(CancellationToken ct = default) =>
        await ReadModels().OrderBy(c => c.ServiceName).ToListAsync(ct);

    public Task<PushChannel?> GetByIdAsync(Guid id, CancellationToken ct = default) =>
        ReadModels().SingleOrDefaultAsync(c => c.Id == id, ct);

    public Task<PushChannel?> GetActiveForServiceAsync(Guid serviceId, CancellationToken ct = default) =>
        ReadModels().SingleOrDefaultAsync(c => c.ServiceId == serviceId && c.IsActive, ct);

    public Task<string?> GetCredentialsAsync(Guid id, CancellationToken ct = default) =>
        db.PushChannels.AsNoTracking().Where(c => c.Id == id).Select(c => c.CredentialsJson).SingleOrDefaultAsync(ct);

    public Task SaveAsync(PushChannel channel, string credentialsJson, bool isNew, CancellationToken ct = default) =>
        mutations.ExecuteAsync(async () =>
        {
            await ValidateServiceAsync(channel, ct);
            var entity = await LoadForSaveAsync(channel.Id, isNew, ct);
            entity.ServiceId = channel.ServiceId;
            entity.FirebaseProjectId = channel.FirebaseProjectId;
            entity.CredentialsJson = credentialsJson;
            entity.IsActive = channel.IsActive;
            entity.Updated = isNew ? null : DateTimeOffset.UtcNow;
            channel.Id = entity.Id;
        }, ct);

    private async Task ValidateServiceAsync(PushChannel channel, CancellationToken ct)
    {
        if (!await db.Services.AnyAsync(s => s.Id == channel.ServiceId, ct))
            throw new PushChannelWriteException("Select an existing service.", false);
        if (await db.PushChannels.AnyAsync(c => c.ServiceId == channel.ServiceId && c.Id != channel.Id, ct))
            throw new PushChannelWriteException("This service already has a push channel. Edit that channel instead.");
    }

    private async Task<PushChannelEntity> LoadForSaveAsync(Guid id, bool isNew, CancellationToken ct)
    {
        if (!isNew)
            return await db.PushChannels.SingleOrDefaultAsync(c => c.Id == id, ct)
                ?? throw new PushChannelWriteException("The push channel no longer exists. Reload the list.");
        var entity = new PushChannelEntity
        {
            Id = id, FirebaseProjectId = string.Empty, CredentialsJson = "{}", Created = DateTimeOffset.UtcNow
        };
        db.PushChannels.Add(entity);
        return entity;
    }

    private IQueryable<PushChannel> ReadModels() => db.PushChannels.AsNoTracking().Select(c => new PushChannel
    {
        Id = c.Id, ServiceId = c.ServiceId, ServiceName = c.Service.Name,
        FirebaseProjectId = c.FirebaseProjectId, IsActive = c.IsActive, Created = c.Created, Updated = c.Updated
    });
}