using JobTrackerApi.Controllers;
using JobTrackerApi.Data;
using JobTrackerApi.Models;
using Microsoft.EntityFrameworkCore;

namespace JobTrackerApi.Services;

public sealed record CvProcessingOutcome(
    bool Succeeded,
    string? FailureCategory = null,
    string? FailureMessage = null,
    bool Retryable = false,
    string? Provider = null,
    string? Model = null,
    string? RouteReason = null);

public interface ICvProcessingQueue
{
    Task<AiOperationAdmissionResult?> EnqueueAsync(int runId, CancellationToken cancellationToken = default);
}

/// <summary>
/// Compatibility name for the CV producer bridge. Durable scheduling and execution are owned by
/// the shared AI operation queue; this type does not keep an in-memory CV queue.
/// </summary>
public sealed class CvProcessingQueue(AiOperationAdmission admission, JobTrackerContext db, IConfiguration configuration) : ICvProcessingQueue
{
    public const string TaskType = "cv.process";
    public const string SubjectType = "cv_extraction_run";

    public async Task<AiOperationAdmissionResult?> EnqueueAsync(int runId, CancellationToken cancellationToken = default)
    {
        var document = await db.CvExtractionRuns.AnyAsync(run => run.Id == runId &&
            run.ParserVersion == ProfileCvController.DocumentParserVersion && run.Trigger == "document_import", cancellationToken);
        if (document && !configuration.GetValue("Workers:AiOperationsEnabled", false) &&
            !configuration.GetValue("Workers:CvDocumentImportsEnabled", false))
            throw new AiOperationAdmissionException("cv_worker_disabled", "CV processing is disabled on this server. Ask the administrator to enable document processing, then retry the upload.", StatusCodes.Status503ServiceUnavailable);
        return await admission.EnqueueAsync(
            TaskType,
            $"run:{runId}",
            SubjectType,
            runId.ToString(System.Globalization.CultureInfo.InvariantCulture),
            AiOperationPriorities.UserVisible,
            cancellationToken);
    }
}

public sealed class NoOpCvProcessingQueue : ICvProcessingQueue
{
    public static readonly NoOpCvProcessingQueue Instance = new();
    public Task<AiOperationAdmissionResult?> EnqueueAsync(int runId, CancellationToken cancellationToken = default)
        => Task.FromResult<AiOperationAdmissionResult?>(null);
}

public sealed class CvProcessingOperationHandler : IAiOperationHandler
{
    public string TaskType => CvProcessingQueue.TaskType;

    public async Task<AiOperationExecutionResult> ExecuteAsync(
        AiOperationExecutionContext context,
        IServiceProvider services,
        CancellationToken cancellationToken)
    {
        if (!string.Equals(context.Lease.SubjectType, CvProcessingQueue.SubjectType, StringComparison.Ordinal) ||
            !int.TryParse(context.Lease.SubjectId, out var runId) || runId <= 0)
        {
            throw new AiOperationFailure("invalid_cv_run", "The CV processing operation has an invalid run reference.", retryable: false);
        }

        CvProcessingOutcome? outcome;
        try
        {
            outcome = await services.GetRequiredService<ProfileCvController>()
                .ProcessQueuedRunAsync(runId, cancellationToken, context);
        }
        catch (OperationCanceledException)
        {
            var operation = await services.GetRequiredService<UserOperationStore>()
                .GetAsync(context.Lease.OperationId, CancellationToken.None);
            await SetRunStatusAsync(
                services,
                runId,
                operation?.CancellationRequestedAtUtc is null ? "queued" : "cancelled",
                operation?.CancellationRequestedAtUtc is null ? "CV processing timed out and may be retried." : "CV processing was cancelled.", context.Lease);
            throw;
        }
        if (outcome is null)
            throw new AiOperationFailure("cv_run_not_found", "The CV processing run is no longer available.", retryable: false);
        if (!outcome.Succeeded)
        {
            if (outcome.Retryable)
            {
                var operation = await services.GetRequiredService<UserOperationStore>()
                    .GetAsync(context.Lease.OperationId, cancellationToken);
                var canRetry = operation is not null && operation.AttemptCount < operation.MaxAttempts &&
                    (operation.DeadlineAtUtc is null || operation.DeadlineAtUtc > DateTime.UtcNow);
                if (!canRetry)
                    await SetRunStatusAsync(services, runId, "failed", outcome.FailureMessage ?? "CV processing failed.", context.Lease);
            }

            if (outcome.Provider is not null || outcome.Model is not null || outcome.RouteReason is not null)
            {
                throw new AiGenerationException(
                    outcome.FailureCategory ?? "cv_processing_failed",
                    outcome.FailureMessage ?? "CV processing failed.",
                    outcome.Retryable,
                    outcome.Provider,
                    outcome.Model,
                    outcome.RouteReason);
            }

            throw new AiOperationFailure(
                outcome.FailureCategory ?? "cv_processing_failed",
                outcome.FailureMessage ?? "CV processing failed.",
                outcome.Retryable);
        }

        var isDocumentImport = await services.GetRequiredService<JobTrackerContext>().CvExtractionRuns.Where(r => r.Id == runId).Select(r => r.ParserVersion).FirstAsync(cancellationToken) == ProfileCvController.DocumentParserVersion;
        return new AiOperationExecutionResult(
            $"/api/profile-cv/runs/{runId}/{(isDocumentImport ? "review" : "diff")}",
            outcome.Provider,
            outcome.Model,
            outcome.RouteReason ?? (isDocumentImport ? "cv_review_ready" : "cv_pipeline"));
    }

    private static Task<int> SetRunStatusAsync(IServiceProvider services, int runId, string status, string message, UserOperationLease lease)
    {
        var completedAtUtc = status == "failed" || status == "cancelled" ? DateTimeOffset.UtcNow : (DateTimeOffset?)null;
        var db = services.GetRequiredService<JobTrackerContext>();
        return db.CvExtractionRuns
            .Where(run => run.Id == runId && (run.Status == "running" || run.Status == "queued") && db.UserOperations.Any(o => o.Id == lease.OperationId && o.LeaseToken == lease.LeaseToken && o.Status == OperationStatuses.Running))
            .ExecuteUpdateAsync(setters => setters
                .SetProperty(run => run.Status, status)
                .SetProperty(run => run.ErrorMessage, message)
                .SetProperty(run => run.CompletedAtUtc, completedAtUtc),
                CancellationToken.None);
    }
}