package sync

import (
	"context"
	"fmt"
	"gorm.io/gorm"
	"log"
	"strings"
	"tercul/internal/platform/config"

	"github.com/weaviate/weaviate-go-client/v5/weaviate"
)

// BatchProcessor handles batch processing of entities for sync operations
type BatchProcessor struct {
	db               *gorm.DB
	defaultBatchSize int
	weaviateClient   *weaviate.Client
}

// NewBatchProcessor creates a new BatchProcessor
func NewBatchProcessor(db *gorm.DB, cfg *config.Config, weaviateClient *weaviate.Client) *BatchProcessor {
	batchSize := cfg.BatchSize
	if batchSize <= 0 {
		batchSize = DefaultBatchSize
	}

	return &BatchProcessor{
		db:               db,
		defaultBatchSize: batchSize,
		weaviateClient:   weaviateClient,
	}
}

// ProcessEntitiesBatch processes a batch of entities from a given table
func (bp *BatchProcessor) ProcessEntitiesBatch(ctx context.Context, className string, batchSize, offset int) error {
	log.Printf("Processing %s batch (offset %d, batch size %d)...", className, offset, batchSize)

	var results []map[string]interface{}
	tableName := toSnakeCase(className)

	if err := bp.db.Table(tableName).Limit(batchSize).Offset(offset).Find(&results).Error; err != nil {
		return fmt.Errorf("error fetching %s batch: %w", className, err)
	}

	if len(results) == 0 {
		log.Printf("No %s records found for batch (offset %d)", className, offset)
		return nil
	}

	return bp.CreateObjectsBatch(ctx, className, results)
}

// ProcessAllEntities processes all entities of a given type in batches
func (bp *BatchProcessor) ProcessAllEntities(ctx context.Context, className string) error {
	log.Printf("Processing all %s entities...", className)

	var count int64
	tableName := toSnakeCase(className)
	if err := bp.db.Table(tableName).Count(&count).Error; err != nil {
		return fmt.Errorf("error counting %s: %w", className, err)
	}

	if count == 0 {
		log.Printf("No %s entities found", className)
		return nil
	}

	for offset := 0; offset < int(count); offset += bp.defaultBatchSize {
		if err := bp.ProcessEntitiesBatch(ctx, className, bp.defaultBatchSize, offset); err != nil {
			log.Printf("Error processing %s batch (offset %d): %v", className, offset, err)
			// Continue with next batch instead of failing completely
		}
	}

	log.Printf("Completed processing all %s entities", className)
	return nil
}

// GetBatchSize returns the configured batch size
func (bp *BatchProcessor) GetBatchSize() int {
	return bp.defaultBatchSize
}

// toSnakeCase converts a class name from CamelCase to snake_case
func toSnakeCase(str string) string {
	// Handle special cases for known entity types
	specialCases := map[string]string{
		"Work":              "work",
		"Translation":       "translation",
		"Author":            "author",
		"Media":             "media",
		"Category":          "category",
		"TopicCluster":      "topic_cluster",
		"LanguageAnalysis":  "language_analysis",
		"WritingStyle":      "writing_style",
		"LanguageEntity":    "language_entity",
		"LinguisticLayer":   "linguistic_layer",
		"EditorialWorkflow": "editorial_workflow",
		"WorkStats":         "work_stats",
		"TranslationStats":  "translation_stats",
		"MediaStats":        "media_stats",
		"UserStats":         "user_stats",
		"BookStats":         "book_stats",
		"CollectionStats":   "collection_stats",
		"TextMetadata":      "text_metadata",
		"PoeticAnalysis":    "poetic_analysis",
		"HybridEntityWork":  "hybrid_entity_work",
		"CopyrightClaim":    "copyright_claim",
	}

	if tableName, exists := specialCases[str]; exists {
		return tableName
	}

	// For other cases, convert CamelCase to snake_case
	var result string
	for i, r := range str {
		if i > 0 && 'A' <= r && r <= 'Z' {
			result += "_"
		}
		result += string(r)
	}
	return strings.ToLower(result)
}

// CreateObjectsBatch creates multiple objects in Weaviate using the existing client
func (bp *BatchProcessor) CreateObjectsBatch(ctx context.Context, className string, objects []map[string]interface{}) error {
	var errors []error

	for _, record := range objects {
		objID := fmt.Sprintf("%v", record["id"])
		if err := bp.createObject(ctx, className, objID, record); err != nil {
			log.Printf("Error syncing %s ID %s: %v", className, objID, err)
			errors = append(errors, err)
		}
	}

	if len(errors) > 0 {
		return fmt.Errorf("batch sync completed with %d errors", len(errors))
	}

	return nil
}

// createObject creates a single object in Weaviate using the injected client.
func (bp *BatchProcessor) createObject(ctx context.Context, className, objID string, properties map[string]interface{}) error {
	_, err := bp.weaviateClient.Data().Creator().
		WithClassName(className).
		WithID(objID).
		WithProperties(properties).
		Do(ctx)

	if err != nil {
		return fmt.Errorf("failed to create %s object with ID %s: %w", className, objID, err)
	}

	log.Printf("Successfully synced %s ID %s", className, objID)
	return nil
}