using Big.Application;
using Big.Infrastructure;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.Abstractions;

namespace Big.Tests;

// S-14 (#15): the escalation drain loop. Mirrors OpenZaakJobProcessor — acquire the parked
// BeoordelingEscaleren jobs, reassign each instance's Beoordelen task to teamlead, then complete the
// job. A job whose reassignment fails is logged and left un-completed for Flowable to redeliver (§8.6).
public class BeoordelingEscalatieProcessorTests
{
    /// <summary>A fake escalation client: scripts the jobs to acquire, records reassignments and
    /// completions, and can be told to throw on reassigning a given instance.</summary>
    private sealed class FakeEscalatieClient(params EscalatieJob[] jobs) : IBeoordelingEscalatieClient
    {
        public int AcquireCount { get; private set; }
        public List<string> Reassigned { get; } = [];
        public List<string> Completed { get; } = [];
        public string? ThrowOnInstance { get; set; }

        public Task<IReadOnlyList<EscalatieJob>> AcquireBeoordelingEscalatieJobsAsync(int maxJobs, CancellationToken ct = default)
        {
            AcquireCount++;
            return Task.FromResult<IReadOnlyList<EscalatieJob>>(jobs.Take(maxJobs).ToList());
        }

        public Task ReassignBeoordelingToTeamleadAsync(string processInstanceId, CancellationToken ct = default)
        {
            if (processInstanceId == ThrowOnInstance)
                throw new InvalidOperationException("reassign failed");
            Reassigned.Add(processInstanceId);
            return Task.CompletedTask;
        }

        public Task CompleteBeoordelingEscalatieJobAsync(string jobId, CancellationToken ct = default)
        {
            Completed.Add(jobId);
            return Task.CompletedTask;
        }
    }

    [Fact]
    public async Task Acquires_an_escalation_reassigns_to_teamlead_and_completes_the_job()
    {
        var client = new FakeEscalatieClient(new EscalatieJob("job-9", "pi-1"));

        var acquired = await new BeoordelingEscalatieProcessor(
            client, NullLogger<BeoordelingEscalatieProcessor>.Instance).PumpOnceAsync(5);

        Assert.Equal(1, acquired);
        Assert.Equal("pi-1", Assert.Single(client.Reassigned));
        Assert.Equal("job-9", Assert.Single(client.Completed));
    }

    [Fact]
    public async Task A_failing_reassign_is_left_uncompleted_for_flowable_to_redeliver()
    {
        var client = new FakeEscalatieClient(new EscalatieJob("job-9", "pi-1")) { ThrowOnInstance = "pi-1" };
        var logger = new CapturingLogger<BeoordelingEscalatieProcessor>();

        var acquired = await new BeoordelingEscalatieProcessor(client, logger).PumpOnceAsync(5);

        Assert.Equal(1, acquired);
        Assert.Empty(client.Completed);
        var error = Assert.Single(logger.Entries, e => e.Level == LogLevel.Error);
        Assert.Contains("job-9", error.Message);
    }

    [Fact]
    public async Task Does_nothing_but_poll_when_there_are_no_escalations()
    {
        var client = new FakeEscalatieClient();

        var acquired = await new BeoordelingEscalatieProcessor(
            client, NullLogger<BeoordelingEscalatieProcessor>.Instance).PumpOnceAsync(5);

        Assert.Equal(0, acquired);
        Assert.Equal(1, client.AcquireCount);
        Assert.Empty(client.Completed);
    }
}