using System;
using System.Collections.Immutable;

namespace StellaOps.Scheduler.Models;

/// <summary>
/// Shared helper for translating persisted <see cref="PolicyRunJob"/> documents into
/// API-facing <see cref="PolicyRunStatus"/> projections.
/// </summary>
public static class PolicyRunStatusFactory
{
    public static PolicyRunStatus Create(PolicyRunJob job, DateTimeOffset nowUtc)
    {
        ArgumentNullException.ThrowIfNull(job);

        var status = MapExecutionStatus(job.Status);
        var queuedAt = job.QueuedAt ?? job.CreatedAt;
        var startedAt = job.SubmittedAt;
        var finishedAt = job.CompletedAt ?? job.CancelledAt;
        var metadata = job.Metadata ?? ImmutableSortedDictionary<string, string>.Empty;
        var inputs = job.Inputs ?? PolicyRunInputs.Empty;
        var policyVersion = job.PolicyVersion
            ?? throw new InvalidOperationException($"Policy run job '{job.Id}' is missing policyVersion.");

        return new PolicyRunStatus(
            job.RunId ?? job.Id,
            job.TenantId,
            job.PolicyId,
            policyVersion,
            job.Mode,
            status,
            job.Priority,
            queuedAt,
            job.Status == PolicyRunJobStatus.Pending ? null : startedAt,
            finishedAt,
            PolicyRunStats.Empty,
            inputs,
            determinismHash: null,
            errorCode: null,
            error: job.Status == PolicyRunJobStatus.Failed ? job.LastError : null,
            attempts: job.AttemptCount,
            traceId: null,
            explainUri: null,
            metadata,
            cancellationRequested: job.CancellationRequested,
            cancellationRequestedAt: job.CancellationRequestedAt,
            cancellationReason: job.CancellationReason,
            SchedulerSchemaVersions.PolicyRunStatus);
    }

    private static PolicyRunExecutionStatus MapExecutionStatus(PolicyRunJobStatus status)
        => status switch
        {
            PolicyRunJobStatus.Pending => PolicyRunExecutionStatus.Queued,
            PolicyRunJobStatus.Dispatching => PolicyRunExecutionStatus.Running,
            PolicyRunJobStatus.Submitted => PolicyRunExecutionStatus.Running,
            PolicyRunJobStatus.Completed => PolicyRunExecutionStatus.Succeeded,
            PolicyRunJobStatus.Failed => PolicyRunExecutionStatus.Failed,
            PolicyRunJobStatus.Cancelled => PolicyRunExecutionStatus.Cancelled,
            _ => PolicyRunExecutionStatus.Queued
        };
}