using System.Text.Json;
using System.Text.Json.Nodes;
using SPTarkov.DI.Annotations;
using SPTarkov.Server.Core.Migration;
using SPTarkov.Server.Core.Models.Eft.Profile;
using SPTarkov.Server.Core.Models.Utils;
using SPTarkov.Server.Core.Utils;

namespace SPTarkov.Server.Core.Services
{
    [Injectable(InjectionType.Singleton)]
    public class ProfileMigratorService(
        IEnumerable<IProfileMigration> profileMigrations,
        TimeUtil timeUtil,
        ISptLogger<ProfileMigratorService> logger
    )
    {
        private IEnumerable<AbstractProfileMigration> _sortedMigrations = [];

        public SptProfile HandlePendingMigrations(JsonObject profile)
        {
            // On the initial run, begin sorting our migrations
            // This will sort it so that any non-prerequisite migrations go first
            // And then all the prerequisite ones.
            if (!_sortedMigrations.Any())
            {
                _sortedMigrations = SortMigrations();
            }

            var profileId = profile["info"]?["id"]?.GetValue<string>();

            // Profile is due for a wipe or a reset, do not continue here.
            if (
                profile["characters"]?["pmc"]?["Info"] == null
                || profile["characters"]?["scav"]?["Info"] == null
                || (profile["info"]?["wipe"]?.GetValue<bool>() == true)
            )
            {
                return profile.Deserialize<SptProfile>(JsonUtil.JsonSerializerOptionsNoIndent)
                    ?? throw new InvalidOperationException($"Could not deserialize the profile {profileId}");
            }

            var ranMigrations = new List<AbstractProfileMigration>();

            foreach (var profileMigration in _sortedMigrations)
            {
                if (profileMigration.CanMigrate(profile, ranMigrations))
                {
                    logger.Warning($"{profileId} has a pending profile migration: {profileMigration.MigrationName}");

                    var migratedProfile = profileMigration.Migrate(profile);

                    if (migratedProfile is not null)
                    {
                        profile = migratedProfile;

                        ranMigrations.Add(profileMigration);
                    }
                }
            }

            var sptReadyProfile =
                profile.Deserialize<SptProfile>(JsonUtil.JsonSerializerOptionsNoIndent)
                ?? throw new InvalidOperationException($"Could not deserialize the profile {profileId}");

            foreach (var ranMigration in ranMigrations)
            {
                if (ranMigration.PostMigrate(sptReadyProfile))
                {
                    logger.Success($"{profileId} successfully ran profile migration: {ranMigration.MigrationName}");

                    if (sptReadyProfile.SptData!.Migrations is null)
                    {
                        sptReadyProfile.SptData.Migrations = [];
                    }

                    sptReadyProfile.SptData.Migrations.Add(ranMigration.MigrationName, timeUtil.GetTimeStamp());
                }
            }

            return sptReadyProfile;
        }

        protected IEnumerable<AbstractProfileMigration> SortMigrations()
        {
            var sortedMigrations = new List<AbstractProfileMigration>();
            var visitedMigrations = new Dictionary<Type, bool>();
            var migrationDict = profileMigrations.Cast<AbstractProfileMigration>().ToDictionary(m => m.GetType());

            foreach (var migration in profileMigrations.Cast<AbstractProfileMigration>())
            {
                VisitMigrationForSort(migration, migrationDict, visitedMigrations, sortedMigrations);
            }

            return sortedMigrations;
        }

        protected void VisitMigrationForSort(
            AbstractProfileMigration migration,
            Dictionary<Type, AbstractProfileMigration> migrationTypeDictionary,
            Dictionary<Type, bool> visitedTypeDictionary,
            List<AbstractProfileMigration> sortedMigrations
        )
        {
            var migrationType = migration.GetType();

            if (visitedTypeDictionary.TryGetValue(migrationType, out var isVisited))
            {
                if (isVisited)
                {
                    return;
                }

                // Big error, two migrations should never depend on one another
                throw new InvalidOperationException($"Cycle detected in migration prerequisites involving: {migrationType.Name}");
            }

            // Mark the current migration type for visiting
            visitedTypeDictionary[migrationType] = false;

            foreach (var prerequisiteType in migration.PrerequisiteMigrations)
            {
                if (!migrationTypeDictionary.TryGetValue(prerequisiteType, out var prereqMigration))
                {
                    continue;
                }

                // Visit the next prerequisite
                VisitMigrationForSort(prereqMigration, migrationTypeDictionary, visitedTypeDictionary, sortedMigrations);
            }

            // Done visiting, mark it as fully visited and add it to the sorted migrations
            visitedTypeDictionary[migrationType] = true;
            sortedMigrations.Add(migration);
        }
    }
}