using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using MongoDB.Bson;
using MongoDB.Driver;
using StellaOps.Feedser.Storage.Mongo.Migrations;

namespace StellaOps.Feedser.Storage.Mongo;

/// <summary>
/// Ensures required collections and indexes exist before the service begins processing.
/// </summary>
public sealed class MongoBootstrapper
{
    private const string RawDocumentBucketName = "documents";
    private static readonly string[] RequiredCollections =
    {
        MongoStorageDefaults.Collections.Source,
        MongoStorageDefaults.Collections.SourceState,
        MongoStorageDefaults.Collections.Document,
        MongoStorageDefaults.Collections.Dto,
        MongoStorageDefaults.Collections.Advisory,
        MongoStorageDefaults.Collections.Alias,
        MongoStorageDefaults.Collections.Affected,
        MongoStorageDefaults.Collections.Reference,
        MongoStorageDefaults.Collections.KevFlag,
        MongoStorageDefaults.Collections.RuFlags,
        MongoStorageDefaults.Collections.JpFlags,
        MongoStorageDefaults.Collections.PsirtFlags,
        MongoStorageDefaults.Collections.MergeEvent,
        MongoStorageDefaults.Collections.ExportState,
        MongoStorageDefaults.Collections.ChangeHistory,
        MongoStorageDefaults.Collections.Locks,
        MongoStorageDefaults.Collections.Jobs,
        MongoStorageDefaults.Collections.Migrations,
    };

    private readonly IMongoDatabase _database;
    private readonly MongoStorageOptions _options;
    private readonly ILogger<MongoBootstrapper> _logger;
    private readonly MongoMigrationRunner _migrationRunner;

    public MongoBootstrapper(
        IMongoDatabase database,
        IOptions<MongoStorageOptions> options,
        ILogger<MongoBootstrapper> logger,
        MongoMigrationRunner migrationRunner)
    {
        _database = database ?? throw new ArgumentNullException(nameof(database));
        _options = options?.Value ?? throw new ArgumentNullException(nameof(options));
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
        _migrationRunner = migrationRunner ?? throw new ArgumentNullException(nameof(migrationRunner));
    }

    public async Task InitializeAsync(CancellationToken cancellationToken)
    {
        var existingCollections = await ListCollectionsAsync(cancellationToken).ConfigureAwait(false);

        foreach (var collectionName in RequiredCollections)
        {
            if (!existingCollections.Contains(collectionName))
            {
                await _database.CreateCollectionAsync(collectionName, cancellationToken: cancellationToken).ConfigureAwait(false);
                _logger.LogInformation("Created Mongo collection {Collection}", collectionName);
            }
        }

        await Task.WhenAll(
            EnsureLocksIndexesAsync(cancellationToken),
            EnsureJobsIndexesAsync(cancellationToken),
            EnsureAdvisoryIndexesAsync(cancellationToken),
            EnsureDocumentsIndexesAsync(cancellationToken),
            EnsureDtoIndexesAsync(cancellationToken),
            EnsureAliasIndexesAsync(cancellationToken),
            EnsureAffectedIndexesAsync(cancellationToken),
            EnsureReferenceIndexesAsync(cancellationToken),
            EnsureSourceStateIndexesAsync(cancellationToken),
            EnsurePsirtFlagIndexesAsync(cancellationToken),
            EnsureChangeHistoryIndexesAsync(cancellationToken),
            EnsureGridFsIndexesAsync(cancellationToken)).ConfigureAwait(false);

        await _migrationRunner.RunAsync(cancellationToken).ConfigureAwait(false);

        _logger.LogInformation("Mongo bootstrapper completed");
    }

    private async Task<HashSet<string>> ListCollectionsAsync(CancellationToken cancellationToken)
    {
        using var cursor = await _database.ListCollectionNamesAsync(cancellationToken: cancellationToken).ConfigureAwait(false);
        var list = await cursor.ToListAsync(cancellationToken).ConfigureAwait(false);
        return new HashSet<string>(list, StringComparer.Ordinal);
    }

    private Task EnsureLocksIndexesAsync(CancellationToken cancellationToken)
    {
        var collection = _database.GetCollection<BsonDocument>(MongoStorageDefaults.Collections.Locks);
        var indexes = new List<CreateIndexModel<BsonDocument>>
        {
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("ttlAt"),
                new CreateIndexOptions { Name = "ttl_at_ttl", ExpireAfter = TimeSpan.Zero }),
        };

        return collection.Indexes.CreateManyAsync(indexes, cancellationToken);
    }

    private Task EnsureJobsIndexesAsync(CancellationToken cancellationToken)
    {
        var collection = _database.GetCollection<BsonDocument>(MongoStorageDefaults.Collections.Jobs);
        var indexes = new List<CreateIndexModel<BsonDocument>>
        {
            new(
                Builders<BsonDocument>.IndexKeys.Descending("createdAt"),
                new CreateIndexOptions { Name = "jobs_createdAt_desc" }),
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("kind").Descending("createdAt"),
                new CreateIndexOptions { Name = "jobs_kind_createdAt" }),
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("status").Descending("createdAt"),
                new CreateIndexOptions { Name = "jobs_status_createdAt" }),
        };

        return collection.Indexes.CreateManyAsync(indexes, cancellationToken);
    }

    private Task EnsureAdvisoryIndexesAsync(CancellationToken cancellationToken)
    {
        var collection = _database.GetCollection<BsonDocument>(MongoStorageDefaults.Collections.Advisory);
        var indexes = new List<CreateIndexModel<BsonDocument>>
        {
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("advisoryKey"),
                new CreateIndexOptions { Name = "advisory_key_unique", Unique = true }),
            new(
                Builders<BsonDocument>.IndexKeys.Descending("modified"),
                new CreateIndexOptions { Name = "advisory_modified_desc" }),
            new(
                Builders<BsonDocument>.IndexKeys.Descending("published"),
                new CreateIndexOptions { Name = "advisory_published_desc" }),
        };

        return collection.Indexes.CreateManyAsync(indexes, cancellationToken);
    }

    private Task EnsureDocumentsIndexesAsync(CancellationToken cancellationToken)
    {
        var collection = _database.GetCollection<BsonDocument>(MongoStorageDefaults.Collections.Document);
        var indexes = new List<CreateIndexModel<BsonDocument>>
        {
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("sourceName").Ascending("uri"),
                new CreateIndexOptions { Name = "document_source_uri_unique", Unique = true }),
            new(
                Builders<BsonDocument>.IndexKeys.Descending("fetchedAt"),
                new CreateIndexOptions { Name = "document_fetchedAt_desc" }),
        };

        var expiresKey = Builders<BsonDocument>.IndexKeys.Ascending("expiresAt");
        var expiresOptions = new CreateIndexOptions<BsonDocument>
        {
            Name = _options.RawDocumentRetention > TimeSpan.Zero ? "document_expiresAt_ttl" : "document_expiresAt",
            PartialFilterExpression = Builders<BsonDocument>.Filter.Exists("expiresAt", true),
        };

        if (_options.RawDocumentRetention > TimeSpan.Zero)
        {
            expiresOptions.ExpireAfter = TimeSpan.Zero;
        }

        indexes.Add(new CreateIndexModel<BsonDocument>(expiresKey, expiresOptions));

        return collection.Indexes.CreateManyAsync(indexes, cancellationToken);
    }

    private Task EnsureAliasIndexesAsync(CancellationToken cancellationToken)
    {
        var collection = _database.GetCollection<BsonDocument>(MongoStorageDefaults.Collections.Alias);
        var indexes = new List<CreateIndexModel<BsonDocument>>
        {
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("scheme").Ascending("value"),
                new CreateIndexOptions { Name = "alias_scheme_value", Unique = false }),
        };

        return collection.Indexes.CreateManyAsync(indexes, cancellationToken);
    }

    private Task EnsureGridFsIndexesAsync(CancellationToken cancellationToken)
    {
        if (_options.RawDocumentRetention <= TimeSpan.Zero)
        {
            return Task.CompletedTask;
        }

        var collectionName = $"{RawDocumentBucketName}.files";
        var collection = _database.GetCollection<BsonDocument>(collectionName);
        var indexes = new List<CreateIndexModel<BsonDocument>>
        {
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("metadata.expiresAt"),
                new CreateIndexOptions<BsonDocument>
                {
                    Name = "gridfs_files_expiresAt_ttl",
                    ExpireAfter = TimeSpan.Zero,
                    PartialFilterExpression = Builders<BsonDocument>.Filter.Exists("metadata.expiresAt", true),
                }),
        };

        return collection.Indexes.CreateManyAsync(indexes, cancellationToken);
    }

    private Task EnsureAffectedIndexesAsync(CancellationToken cancellationToken)
    {
        var collection = _database.GetCollection<BsonDocument>(MongoStorageDefaults.Collections.Affected);
        var indexes = new List<CreateIndexModel<BsonDocument>>
        {
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("platform").Ascending("name"),
                new CreateIndexOptions { Name = "affected_platform_name" }),
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("advisoryId"),
                new CreateIndexOptions { Name = "affected_advisoryId" }),
        };

        return collection.Indexes.CreateManyAsync(indexes, cancellationToken);
    }

    private Task EnsureReferenceIndexesAsync(CancellationToken cancellationToken)
    {
        var collection = _database.GetCollection<BsonDocument>(MongoStorageDefaults.Collections.Reference);
        var indexes = new List<CreateIndexModel<BsonDocument>>
        {
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("url"),
                new CreateIndexOptions { Name = "reference_url" }),
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("advisoryId"),
                new CreateIndexOptions { Name = "reference_advisoryId" }),
        };

        return collection.Indexes.CreateManyAsync(indexes, cancellationToken);
    }

    private Task EnsureSourceStateIndexesAsync(CancellationToken cancellationToken)
    {
        var collection = _database.GetCollection<BsonDocument>(MongoStorageDefaults.Collections.SourceState);
        var indexes = new List<CreateIndexModel<BsonDocument>>
        {
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("sourceName"),
                new CreateIndexOptions { Name = "source_state_unique", Unique = true }),
        };

        return collection.Indexes.CreateManyAsync(indexes, cancellationToken);
    }

    private Task EnsureDtoIndexesAsync(CancellationToken cancellationToken)
    {
        var collection = _database.GetCollection<BsonDocument>(MongoStorageDefaults.Collections.Dto);
        var indexes = new List<CreateIndexModel<BsonDocument>>
        {
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("documentId"),
                new CreateIndexOptions { Name = "dto_documentId" }),
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("sourceName").Descending("validatedAt"),
                new CreateIndexOptions { Name = "dto_source_validated" }),
        };

        return collection.Indexes.CreateManyAsync(indexes, cancellationToken);
    }

    private async Task EnsurePsirtFlagIndexesAsync(CancellationToken cancellationToken)
    {
        var collection = _database.GetCollection<BsonDocument>(MongoStorageDefaults.Collections.PsirtFlags);
        try
        {
            await collection.Indexes.DropOneAsync("psirt_advisoryKey_unique", cancellationToken).ConfigureAwait(false);
        }
        catch (MongoCommandException ex) when (ex.CodeName == "IndexNotFound")
        {
        }

        var index = new CreateIndexModel<BsonDocument>(
            Builders<BsonDocument>.IndexKeys.Ascending("vendor"),
            new CreateIndexOptions { Name = "psirt_vendor" });

        await collection.Indexes.CreateOneAsync(index, cancellationToken: cancellationToken).ConfigureAwait(false);
    }

    private Task EnsureChangeHistoryIndexesAsync(CancellationToken cancellationToken)
    {
        var collection = _database.GetCollection<BsonDocument>(MongoStorageDefaults.Collections.ChangeHistory);
        var indexes = new List<CreateIndexModel<BsonDocument>>
        {
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("source").Ascending("advisoryKey").Descending("capturedAt"),
                new CreateIndexOptions { Name = "history_source_advisory_capturedAt" }),
            new(
                Builders<BsonDocument>.IndexKeys.Descending("capturedAt"),
                new CreateIndexOptions { Name = "history_capturedAt" }),
            new(
                Builders<BsonDocument>.IndexKeys.Ascending("documentId"),
                new CreateIndexOptions { Name = "history_documentId" })
        };

        return collection.Indexes.CreateManyAsync(indexes, cancellationToken);
    }
}