//                           _       _
// __      _____  __ ___   ___  __ _| |_ ___
// \ \ /\ / / _ \/ _` \ \ / / |/ _` | __/ _ \
//  \ V  V /  __/ (_| |\ V /| | (_| | ||  __/
//   \_/\_/ \___|\__,_| \_/ |_|\__,_|\__\___|
//
//  Copyright © 2016 - 2024 Weaviate B.V. All rights reserved.
//
//  CONTACT: hello@weaviate.io
//

/* Remark:

In the current implementation, there is no guarantee of consistent updates to the schema
as updating the actual index and the schema itself is not an atomic operation.
Resolving this issue is beyond the scope of this PR,
but it will be addressed in a separate task specifically dedicated to it.
*/

package schema

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"

	"github.com/pkg/errors"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/weaviate/weaviate/adapters/repos/db/inverted/stopwords"
	"github.com/weaviate/weaviate/entities/backup"
	"github.com/weaviate/weaviate/entities/models"
	"github.com/weaviate/weaviate/entities/schema"
	"github.com/weaviate/weaviate/usecases/config"
	"github.com/weaviate/weaviate/usecases/monitoring"
	"github.com/weaviate/weaviate/usecases/replica"
	"github.com/weaviate/weaviate/usecases/sharding"
)

// AddClass to the schema
func (m *Manager) AddClass(ctx context.Context, principal *models.Principal,
	class *models.Class,
) error {
	err := m.Authorizer.Authorize(principal, "create", "schema/objects")
	if err != nil {
		return err
	}

	shardState, err := m.addClass(ctx, class)
	if err != nil {
		return err
	}

	// call to migrator needs to be outside the lock that is set in addClass
	return m.migrator.AddClass(ctx, class, shardState)
	// TODO gh-846: Rollback state update if migration fails
}

func (m *Manager) RestoreClass(ctx context.Context, d *backup.ClassDescriptor, nodeMapping map[string]string) error {
	// get schema and sharding state
	class := &models.Class{}
	if err := json.Unmarshal(d.Schema, &class); err != nil {
		return fmt.Errorf("marshal class schema: %w", err)
	}
	var shardingState sharding.State
	if d.ShardingState != nil {
		err := json.Unmarshal(d.ShardingState, &shardingState)
		if err != nil {
			return fmt.Errorf("marshal sharding state: %w", err)
		}
	}

	m.Lock()
	defer m.Unlock()
	metric, err := monitoring.GetMetrics().BackupRestoreClassDurations.GetMetricWithLabelValues(class.Class)
	if err == nil {
		timer := prometheus.NewTimer(metric)
		defer timer.ObserveDuration()
	}

	class.Class = schema.UppercaseClassName(class.Class)
	class.Properties = schema.LowercaseAllPropertyNames(class.Properties)

	m.setClassDefaults(class)
	err = m.validateCanAddClass(ctx, class, true)
	if err != nil {
		return err
	}
	// migrate only after validation in completed
	m.migrateClassSettings(class)

	err = m.parseShardingConfig(ctx, class)
	if err != nil {
		return err
	}

	err = m.parseVectorIndexConfig(ctx, class)
	if err != nil {
		return err
	}

	err = m.invertedConfigValidator(class.InvertedIndexConfig)
	if err != nil {
		return err
	}

	shardingState.MigrateFromOldFormat()
	shardingState.ApplyNodeMapping(nodeMapping)

	payload, err := CreateClassPayload(class, &shardingState)
	if err != nil {
		return err
	}
	shardingState.SetLocalName(m.clusterState.LocalName())
	m.schemaCache.addClass(class, &shardingState)

	if err := m.repo.NewClass(ctx, payload); err != nil {
		return err
	}
	m.logger.
		WithField("action", "schema_restore_class").
		Debugf("restore class %q from schema", class.Class)
	m.triggerSchemaUpdateCallbacks()

	out := m.migrator.AddClass(ctx, class, &shardingState)
	return out
}

func (m *Manager) addClass(ctx context.Context, class *models.Class,
) (*sharding.State, error) {
	m.Lock()
	defer m.Unlock()

	class.Class = schema.UppercaseClassName(class.Class)
	class.Properties = schema.LowercaseAllPropertyNames(class.Properties)
	if class.ShardingConfig != nil && schema.MultiTenancyEnabled(class) {
		return nil, fmt.Errorf("cannot have both shardingConfig and multiTenancyConfig")
	} else if class.MultiTenancyConfig == nil {
		class.MultiTenancyConfig = &models.MultiTenancyConfig{}
	} else if class.MultiTenancyConfig.Enabled {
		class.ShardingConfig = sharding.Config{DesiredCount: 0} // tenant shards will be created dynamically
	}

	m.setClassDefaults(class)
	err := m.validateCanAddClass(ctx, class, false)
	if err != nil {
		return nil, err
	}
	// migrate only after validation in completed
	m.migrateClassSettings(class)

	err = m.parseShardingConfig(ctx, class)
	if err != nil {
		return nil, err
	}

	err = m.parseVectorIndexConfig(ctx, class)
	if err != nil {
		return nil, err
	}

	err = m.invertedConfigValidator(class.InvertedIndexConfig)
	if err != nil {
		return nil, err
	}

	shardState, err := sharding.InitState(class.Class,
		class.ShardingConfig.(sharding.Config),
		m.clusterState, class.ReplicationConfig.Factor,
		schema.MultiTenancyEnabled(class))
	if err != nil {
		return nil, errors.Wrap(err, "init sharding state")
	}

	tx, err := m.cluster.BeginTransaction(ctx, AddClass,
		AddClassPayload{class, shardState}, DefaultTxTTL)
	if err != nil {
		// possible causes for errors could be nodes down (we expect every node to
		// the up for a schema transaction) or concurrent transactions from other
		// nodes
		return nil, errors.Wrap(err, "open cluster-wide transaction")
	}

	if err := m.cluster.CommitWriteTransaction(ctx, tx); err != nil {
		// Only log the commit error, but do not abort the changes locally. Once
		// we've told others to commit, we also need to commit ourselves!
		//
		// The idea is that if we abort our changes we are guaranteed to create an
		// inconsistency as soon as any other node honored the commit. This would
		// for example be the case in a 3-node cluster where node 1 is the
		// coordinator, node 2 honored the commit and node 3 died during the commit
		// phase.
		//
		// In this scenario it is far more desirable to make sure that node 1 and
		// node 2 stay in sync, as node 3 - who may or may not have missed the
		// update - can use a local WAL from the first TX phase to replay any
		// missing changes once it's back.
		m.logger.WithError(err).Errorf("not every node was able to commit")
	}

	if err := m.addClassApplyChanges(ctx, class, shardState); err != nil {
		return nil, err
	}
	return shardState, nil
}

func (m *Manager) addClassApplyChanges(ctx context.Context, class *models.Class,
	shardingState *sharding.State,
) error {
	payload, err := CreateClassPayload(class, shardingState)
	if err != nil {
		return err
	}
	if err := m.repo.NewClass(ctx, payload); err != nil {
		return err
	}

	m.logger.
		WithField("action", "schema_add_class").
		Debugf("add class %q from schema", class.Class)

	m.schemaCache.addClass(class, shardingState)

	m.triggerSchemaUpdateCallbacks()
	return nil
}

func (m *Manager) setClassDefaults(class *models.Class) {
	if class.Vectorizer == "" {
		class.Vectorizer = m.config.DefaultVectorizerModule
	}

	if class.VectorIndexType == "" {
		class.VectorIndexType = "hnsw"
	}

	if m.config.DefaultVectorDistanceMetric != "" {
		if class.VectorIndexConfig == nil {
			class.VectorIndexConfig = map[string]interface{}{"distance": m.config.DefaultVectorDistanceMetric}
		} else if class.VectorIndexConfig.(map[string]interface{})["distance"] == nil {
			class.VectorIndexConfig.(map[string]interface{})["distance"] = m.config.DefaultVectorDistanceMetric
		}
	}

	setInvertedConfigDefaults(class)
	for _, prop := range class.Properties {
		setPropertyDefaults(prop)
	}

	m.moduleConfig.SetClassDefaults(class)
}

func setPropertyDefaults(prop *models.Property) {
	setPropertyDefaultTokenization(prop)
	setPropertyDefaultIndexing(prop)
	setNestedPropertiesDefaults(prop.NestedProperties)
}

func setPropertyDefaultTokenization(prop *models.Property) {
	switch dataType, _ := schema.AsPrimitive(prop.DataType); dataType {
	case schema.DataTypeString, schema.DataTypeStringArray:
		// deprecated as of v1.19, default tokenization was word
		// which will be migrated to text+whitespace
		if prop.Tokenization == "" {
			prop.Tokenization = models.PropertyTokenizationWord
		}
	case schema.DataTypeText, schema.DataTypeTextArray:
		if prop.Tokenization == "" {
			prop.Tokenization = models.PropertyTokenizationWord
		}
	default:
		// tokenization not supported for other data types
	}
}

func setPropertyDefaultIndexing(prop *models.Property) {
	// if IndexInverted is set but IndexFilterable and IndexSearchable are not
	// migrate IndexInverted later.
	if prop.IndexInverted != nil &&
		prop.IndexFilterable == nil &&
		prop.IndexSearchable == nil {
		return
	}

	vTrue := true
	vFalse := false

	if prop.IndexFilterable == nil {
		prop.IndexFilterable = &vTrue

		primitiveDataType, isPrimitive := schema.AsPrimitive(prop.DataType)
		if isPrimitive && primitiveDataType == schema.DataTypeBlob {
			prop.IndexFilterable = &vFalse
		}
	}

	if prop.IndexSearchable == nil {
		prop.IndexSearchable = &vFalse

		if dataType, isPrimitive := schema.AsPrimitive(prop.DataType); isPrimitive {
			switch dataType {
			case schema.DataTypeString, schema.DataTypeStringArray:
				// string/string[] are migrated to text/text[] later,
				// at this point they are still valid data types, therefore should be handled here
				prop.IndexSearchable = &vTrue
			case schema.DataTypeText, schema.DataTypeTextArray:
				prop.IndexSearchable = &vTrue
			default:
				// do nothing
			}
		}
	}
}

func setNestedPropertiesDefaults(properties []*models.NestedProperty) {
	for _, property := range properties {
		primitiveDataType, isPrimitive := schema.AsPrimitive(property.DataType)
		nestedDataType, isNested := schema.AsNested(property.DataType)

		setNestedPropertyDefaultTokenization(property, primitiveDataType, nestedDataType, isPrimitive, isNested)
		setNestedPropertyDefaultIndexing(property, primitiveDataType, nestedDataType, isPrimitive, isNested)

		if isNested {
			setNestedPropertiesDefaults(property.NestedProperties)
		}
	}
}

func setNestedPropertyDefaultTokenization(property *models.NestedProperty,
	primitiveDataType, nestedDataType schema.DataType,
	isPrimitive, isNested bool,
) {
	if property.Tokenization == "" && isPrimitive {
		switch primitiveDataType {
		case schema.DataTypeText, schema.DataTypeTextArray:
			property.Tokenization = models.NestedPropertyTokenizationWord
		default:
			// do nothing
		}
	}
}

func setNestedPropertyDefaultIndexing(property *models.NestedProperty,
	primitiveDataType, nestedDataType schema.DataType,
	isPrimitive, isNested bool,
) {
	vTrue := true
	vFalse := false

	if property.IndexFilterable == nil {
		property.IndexFilterable = &vTrue

		if isPrimitive && primitiveDataType == schema.DataTypeBlob {
			property.IndexFilterable = &vFalse
		}
	}

	if property.IndexSearchable == nil {
		property.IndexSearchable = &vFalse

		if isPrimitive {
			switch primitiveDataType {
			case schema.DataTypeText, schema.DataTypeTextArray:
				property.IndexSearchable = &vTrue
			default:
				// do nothing
			}
		}
	}
}

func (m *Manager) migrateClassSettings(class *models.Class) {
	for _, prop := range class.Properties {
		migratePropertySettings(prop)
	}
}

func migratePropertySettings(prop *models.Property) {
	migratePropertyDataTypeAndTokenization(prop)
	migratePropertyIndexInverted(prop)
}

// as of v1.19 DataTypeString and DataTypeStringArray are deprecated
// here both are changed to Text/TextArray
// and proper, backward compatible tokenization
func migratePropertyDataTypeAndTokenization(prop *models.Property) {
	switch dataType, _ := schema.AsPrimitive(prop.DataType); dataType {
	case schema.DataTypeString:
		prop.DataType = schema.DataTypeText.PropString()
	case schema.DataTypeStringArray:
		prop.DataType = schema.DataTypeTextArray.PropString()
	default:
		// other types need no migration and do not support tokenization
		return
	}

	switch prop.Tokenization {
	case models.PropertyTokenizationWord:
		prop.Tokenization = models.PropertyTokenizationWhitespace
	case models.PropertyTokenizationField:
		// stays field
	}
}

// as of v1.19 IndexInverted is deprecated and replaced with
// IndexFilterable (set inverted index)
// and IndexSearchable (map inverted index with term frequencies;
// therefore applicable only to text/text[] data types)
func migratePropertyIndexInverted(prop *models.Property) {
	// if none of new options is set, use inverted settings
	if prop.IndexInverted != nil &&
		prop.IndexFilterable == nil &&
		prop.IndexSearchable == nil {
		prop.IndexFilterable = prop.IndexInverted
		switch dataType, _ := schema.AsPrimitive(prop.DataType); dataType {
		// string/string[] are already migrated into text/text[], can be skipped here
		case schema.DataTypeText, schema.DataTypeTextArray:
			prop.IndexSearchable = prop.IndexInverted
		default:
			vFalse := false
			prop.IndexSearchable = &vFalse
		}
	}
	// new options have precedence so inverted can be reset
	prop.IndexInverted = nil
}

func (m *Manager) validateCanAddClass(
	ctx context.Context, class *models.Class,
	relaxCrossRefValidation bool,
) error {
	if err := m.validateClassNameUniqueness(class.Class); err != nil {
		return err
	}

	if err := m.validateClassName(ctx, class.Class); err != nil {
		return err
	}

	existingPropertyNames := map[string]bool{}
	for _, property := range class.Properties {
		if err := m.validateProperty(property, class.Class, existingPropertyNames, relaxCrossRefValidation); err != nil {
			return err
		}
		existingPropertyNames[strings.ToLower(property.Name)] = true
	}

	if err := m.validateVectorSettings(ctx, class); err != nil {
		return err
	}

	if err := m.moduleConfig.ValidateClass(ctx, class); err != nil {
		return err
	}

	if err := replica.ValidateConfig(class, m.config.Replication); err != nil {
		return err
	}

	// all is fine!
	return nil
}

func (m *Manager) validateProperty(
	property *models.Property, className string,
	existingPropertyNames map[string]bool, relaxCrossRefValidation bool,
) error {
	if _, err := schema.ValidatePropertyName(property.Name); err != nil {
		return err
	}

	if err := schema.ValidateReservedPropertyName(property.Name); err != nil {
		return err
	}

	if existingPropertyNames[strings.ToLower(property.Name)] {
		return fmt.Errorf("class %q: conflict for property %q: already in use or provided multiple times", property.Name, className)
	}

	// Validate data type of property.
	sch := m.getSchema()

	propertyDataType, err := (&sch).FindPropertyDataTypeWithRefs(property.DataType,
		relaxCrossRefValidation, schema.ClassName(className))
	if err != nil {
		return fmt.Errorf("property '%s': invalid dataType: %v", property.Name, err)
	}

	if propertyDataType.IsNested() {
		if err := validateNestedProperties(property.NestedProperties, property.Name); err != nil {
			return err
		}
	} else {
		if len(property.NestedProperties) > 0 {
			return fmt.Errorf("property '%s': nestedProperties not allowed for data types other than object/object[]",
				property.Name)
		}
	}

	if err := m.validatePropertyTokenization(property.Tokenization, propertyDataType); err != nil {
		return err
	}

	if err := m.validatePropertyIndexing(property); err != nil {
		return err
	}

	// all is fine!
	return nil
}

func (m *Manager) parseVectorIndexConfig(ctx context.Context,
	class *models.Class,
) error {
	if class.VectorIndexType != "hnsw" && class.VectorIndexType != "flat" {
		return errors.Errorf(
			"parse vector index config: unsupported vector index type: %q",
			class.VectorIndexType)
	}

	parsed, err := m.configParser(class.VectorIndexConfig, class.VectorIndexType)
	if err != nil {
		return errors.Wrap(err, "parse vector index config")
	}

	class.VectorIndexConfig = parsed

	return nil
}

func (m *Manager) parseShardingConfig(ctx context.Context, class *models.Class) (err error) {
	// multiTenancyConfig and shardingConfig are mutually exclusive
	cfg := sharding.Config{} // cfg is empty in case of MT
	if !schema.MultiTenancyEnabled(class) {
		cfg, err = sharding.ParseConfig(class.ShardingConfig,
			m.clusterState.NodeCount())
		if err != nil {
			return fmt.Errorf("parse sharding config: %w", err)
		}

	}
	class.ShardingConfig = cfg
	return nil
}

func setInvertedConfigDefaults(class *models.Class) {
	if class.InvertedIndexConfig == nil {
		class.InvertedIndexConfig = &models.InvertedIndexConfig{}
	}

	if class.InvertedIndexConfig.CleanupIntervalSeconds == 0 {
		class.InvertedIndexConfig.CleanupIntervalSeconds = config.DefaultCleanupIntervalSeconds
	}

	if class.InvertedIndexConfig.Bm25 == nil {
		class.InvertedIndexConfig.Bm25 = &models.BM25Config{
			K1: config.DefaultBM25k1,
			B:  config.DefaultBM25b,
		}
	}

	if class.InvertedIndexConfig.Stopwords == nil {
		class.InvertedIndexConfig.Stopwords = &models.StopwordConfig{
			Preset: stopwords.EnglishPreset,
		}
	}
}

func CreateClassPayload(class *models.Class,
	shardingState *sharding.State,
) (pl ClassPayload, err error) {
	pl.Name = class.Class
	if pl.Metadata, err = json.Marshal(class); err != nil {
		return pl, fmt.Errorf("marshal class %q metadata: %w", pl.Name, err)
	}
	if shardingState != nil {
		ss := *shardingState
		pl.Shards = make([]KeyValuePair, len(ss.Physical))
		i := 0
		for name, shard := range ss.Physical {
			data, err := json.Marshal(shard)
			if err != nil {
				return pl, fmt.Errorf("marshal shard %q metadata: %w", name, err)
			}
			pl.Shards[i] = KeyValuePair{Key: name, Value: data}
			i++
		}
		ss.Physical = nil
		if pl.ShardingState, err = json.Marshal(&ss); err != nil {
			return pl, fmt.Errorf("marshal class %q sharding state: %w", pl.Name, err)
		}
	}
	return pl, nil
}