using Microsoft.Extensions.DependencyInjection;
using StellaOps.DependencyInjection;
using StellaOps.Notify.Engine;
using StellaOps.Notify.Models;
using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

namespace StellaOps.Notify.Connectors.Slack;

[ServiceBinding(typeof(INotifyChannelHealthProvider), ServiceLifetime.Singleton)]
public sealed class SlackChannelHealthProvider : INotifyChannelHealthProvider
{
    public NotifyChannelType ChannelType => NotifyChannelType.Slack;

    public Task<ChannelHealthResult> CheckAsync(ChannelHealthContext context, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(context);
        cancellationToken.ThrowIfCancellationRequested();

        var builder = SlackMetadataBuilder.CreateBuilder(context)
            .Add("slack.channel.enabled", context.Channel.Enabled ? "true" : "false")
            .Add("slack.validation.targetPresent", HasConfiguredTarget(context.Channel) ? "true" : "false");

        var metadata = builder.Build();
        var status = ResolveStatus(context.Channel);
        var message = status switch
        {
            ChannelHealthStatus.Healthy => "Slack channel configuration validated.",
            ChannelHealthStatus.Degraded => "Slack channel is disabled; enable it to resume deliveries.",
            ChannelHealthStatus.Unhealthy => "Slack channel is missing a configured destination (target).",
            _ => "Slack channel diagnostics completed."
        };

        return Task.FromResult(new ChannelHealthResult(status, message, metadata));
    }

    private static ChannelHealthStatus ResolveStatus(NotifyChannel channel)
    {
        if (!HasConfiguredTarget(channel))
        {
            return ChannelHealthStatus.Unhealthy;
        }

        if (!channel.Enabled)
        {
            return ChannelHealthStatus.Degraded;
        }

        return ChannelHealthStatus.Healthy;
    }

    private static bool HasConfiguredTarget(NotifyChannel channel)
        => !string.IsNullOrWhiteSpace(channel.Config.Target);
}