// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using Aspire.Dashboard.Otlp.Model;
 
namespace Aspire.Dashboard.Model.Otlp;
 
public static class ApplicationsSelectHelpers
{
    public static SelectViewModel<ResourceTypeDetails> GetApplication(this ICollection<SelectViewModel<ResourceTypeDetails>> applications, ILogger logger, string? name, bool canSelectGrouping, SelectViewModel<ResourceTypeDetails> fallback)
    {
        if (name is null)
        {
            return fallback;
        }
 
        var allowedMatches = applications.Where(e => SupportType(e.Id?.Type, canSelectGrouping)).ToList();
 
        // First attempt an exact match on the instance id.
        var instanceIdMatches = allowedMatches.Where(e => string.Equals(name, e.Id?.InstanceId, StringComparisons.ResourceName)).ToList();
        if (instanceIdMatches.Count == 1)
        {
            return instanceIdMatches[0];
        }
        else if (instanceIdMatches.Count == 0)
        {
            // Fallback to matching on app name. This is commonly used when there is only one instance of the app.
            var replicaSetMatches = allowedMatches.Where(e => e.Id?.Type != OtlpApplicationType.Instance && string.Equals(name, e.Id?.ReplicaSetName, StringComparisons.ResourceName)).ToList();
 
            if (replicaSetMatches.Count == 1)
            {
                return replicaSetMatches[0];
            }
            else if (replicaSetMatches.Count == 0)
            {
                // No matches found so return the passed in fallback.
                return fallback;
            }
            else
            {
                return MultipleMatches(allowedMatches, logger, name, replicaSetMatches);
            }
        }
        else
        {
            return MultipleMatches(allowedMatches, logger, name, instanceIdMatches);
        }
 
        static SelectViewModel<ResourceTypeDetails> MultipleMatches(ICollection<SelectViewModel<ResourceTypeDetails>> applications, ILogger logger, string name, List<SelectViewModel<ResourceTypeDetails>> matches)
        {
            // There are multiple matches. Log as much information as possible about applications.
            logger.LogWarning(
                """
                Multiple matches found when getting application '{Name}'.
                Available applications:
                {AvailableApplications}
                Matched applications:
                {MatchedApplications}
                """, name, string.Join(Environment.NewLine, applications), string.Join(Environment.NewLine, matches));
 
            // Return first match to not break app. Make the UI resilient to unexpectedly bad data.
            return matches[0];
        }
    }
 
    public static List<SelectViewModel<ResourceTypeDetails>> CreateApplications(List<OtlpApplication> applications)
    {
        var replicasByApplicationName = OtlpApplication.GetReplicasByApplicationName(applications);
 
        var selectViewModels = new List<SelectViewModel<ResourceTypeDetails>>();
 
        foreach (var (applicationName, replicas) in replicasByApplicationName)
        {
            if (replicas.Count == 1)
            {
                // not replicated
                var app = replicas.Single();
                selectViewModels.Add(new SelectViewModel<ResourceTypeDetails>
                {
                    Id = ResourceTypeDetails.CreateSingleton($"{applicationName}-{app.InstanceId}", applicationName),
                    Name = applicationName
                });
 
                continue;
            }
 
            // add a disabled "Resource" as a header
            selectViewModels.Add(new SelectViewModel<ResourceTypeDetails>
            {
                Id = ResourceTypeDetails.CreateApplicationGrouping(applicationName, isReplicaSet: true),
                Name = applicationName
            });
 
            // add each individual replica
            selectViewModels.AddRange(replicas.Select(replica =>
                new SelectViewModel<ResourceTypeDetails>
                {
                    Id = ResourceTypeDetails.CreateReplicaInstance($"{applicationName}-{replica.InstanceId}", applicationName),
                    Name = OtlpApplication.GetResourceName(replica, applications)
                }));
        }
 
        var sortedVMs = selectViewModels.OrderBy(vm => vm.Name, StringComparers.ResourceName).ToList();
        return sortedVMs;
    }
 
    private static bool SupportType(OtlpApplicationType? type, bool canSelectGrouping)
    {
        if (type is OtlpApplicationType.Instance or OtlpApplicationType.Singleton)
        {
            return true;
        }
 
        if (canSelectGrouping && type is OtlpApplicationType.ResourceGrouping)
        {
            return true;
        }
 
        return false;
    }
}