package database

import (
	"context"
	"database/sql"
	"fmt"
)

type ChunkFileRepository struct {
	db *DB
}

func NewChunkFileRepository(db *DB) *ChunkFileRepository {
	return &ChunkFileRepository{db: db}
}

func (r *ChunkFileRepository) Create(ctx context.Context, tx *sql.Tx, cf *ChunkFile) error {
	query := `
		INSERT INTO chunk_files (chunk_hash, file_id, file_offset, length)
		VALUES (?, ?, ?, ?)
		ON CONFLICT(chunk_hash, file_id) DO NOTHING
	`

	var err error
	if tx != nil {
		_, err = tx.ExecContext(ctx, query, cf.ChunkHash, cf.FileID, cf.FileOffset, cf.Length)
	} else {
		_, err = r.db.ExecWithLog(ctx, query, cf.ChunkHash, cf.FileID, cf.FileOffset, cf.Length)
	}

	if err != nil {
		return fmt.Errorf("inserting chunk_file: %w", err)
	}

	return nil
}

func (r *ChunkFileRepository) GetByChunkHash(ctx context.Context, chunkHash string) ([]*ChunkFile, error) {
	query := `
		SELECT chunk_hash, file_id, file_offset, length
		FROM chunk_files
		WHERE chunk_hash = ?
	`

	rows, err := r.db.conn.QueryContext(ctx, query, chunkHash)
	if err != nil {
		return nil, fmt.Errorf("querying chunk files: %w", err)
	}
	defer CloseRows(rows)

	var chunkFiles []*ChunkFile
	for rows.Next() {
		var cf ChunkFile
		err := rows.Scan(&cf.ChunkHash, &cf.FileID, &cf.FileOffset, &cf.Length)
		if err != nil {
			return nil, fmt.Errorf("scanning chunk file: %w", err)
		}
		chunkFiles = append(chunkFiles, &cf)
	}

	return chunkFiles, rows.Err()
}

func (r *ChunkFileRepository) GetByFilePath(ctx context.Context, filePath string) ([]*ChunkFile, error) {
	query := `
		SELECT cf.chunk_hash, cf.file_id, cf.file_offset, cf.length
		FROM chunk_files cf
		JOIN files f ON cf.file_id = f.id
		WHERE f.path = ?
	`

	rows, err := r.db.conn.QueryContext(ctx, query, filePath)
	if err != nil {
		return nil, fmt.Errorf("querying chunk files: %w", err)
	}
	defer CloseRows(rows)

	var chunkFiles []*ChunkFile
	for rows.Next() {
		var cf ChunkFile
		err := rows.Scan(&cf.ChunkHash, &cf.FileID, &cf.FileOffset, &cf.Length)
		if err != nil {
			return nil, fmt.Errorf("scanning chunk file: %w", err)
		}
		chunkFiles = append(chunkFiles, &cf)
	}

	return chunkFiles, rows.Err()
}

// GetByFileID retrieves chunk files by file ID
func (r *ChunkFileRepository) GetByFileID(ctx context.Context, fileID string) ([]*ChunkFile, error) {
	query := `
		SELECT chunk_hash, file_id, file_offset, length
		FROM chunk_files
		WHERE file_id = ?
	`

	rows, err := r.db.conn.QueryContext(ctx, query, fileID)
	if err != nil {
		return nil, fmt.Errorf("querying chunk files: %w", err)
	}
	defer CloseRows(rows)

	var chunkFiles []*ChunkFile
	for rows.Next() {
		var cf ChunkFile
		err := rows.Scan(&cf.ChunkHash, &cf.FileID, &cf.FileOffset, &cf.Length)
		if err != nil {
			return nil, fmt.Errorf("scanning chunk file: %w", err)
		}
		chunkFiles = append(chunkFiles, &cf)
	}

	return chunkFiles, rows.Err()
}

// DeleteByFileID deletes all chunk_files entries for a given file ID
func (r *ChunkFileRepository) DeleteByFileID(ctx context.Context, tx *sql.Tx, fileID string) error {
	query := `DELETE FROM chunk_files WHERE file_id = ?`

	var err error
	if tx != nil {
		_, err = tx.ExecContext(ctx, query, fileID)
	} else {
		_, err = r.db.ExecWithLog(ctx, query, fileID)
	}

	if err != nil {
		return fmt.Errorf("deleting chunk files: %w", err)
	}

	return nil
}

// DeleteByFileIDs deletes all chunk_files for multiple files in a single statement.
func (r *ChunkFileRepository) DeleteByFileIDs(ctx context.Context, tx *sql.Tx, fileIDs []string) error {
	if len(fileIDs) == 0 {
		return nil
	}

	// Batch at 500 to stay within SQLite's variable limit
	const batchSize = 500

	for i := 0; i < len(fileIDs); i += batchSize {
		end := i + batchSize
		if end > len(fileIDs) {
			end = len(fileIDs)
		}
		batch := fileIDs[i:end]

		query := "DELETE FROM chunk_files WHERE file_id IN (?" + repeatPlaceholder(len(batch)-1) + ")"
		args := make([]interface{}, len(batch))
		for j, id := range batch {
			args[j] = id
		}

		var err error
		if tx != nil {
			_, err = tx.ExecContext(ctx, query, args...)
		} else {
			_, err = r.db.ExecWithLog(ctx, query, args...)
		}
		if err != nil {
			return fmt.Errorf("batch deleting chunk_files: %w", err)
		}
	}

	return nil
}

// CreateBatch inserts multiple chunk_files in a single statement for efficiency.
func (r *ChunkFileRepository) CreateBatch(ctx context.Context, tx *sql.Tx, cfs []ChunkFile) error {
	if len(cfs) == 0 {
		return nil
	}

	// Each ChunkFile has 4 values, so batch at 200 to be safe with SQLite's variable limit
	const batchSize = 200

	for i := 0; i < len(cfs); i += batchSize {
		end := i + batchSize
		if end > len(cfs) {
			end = len(cfs)
		}
		batch := cfs[i:end]

		query := "INSERT INTO chunk_files (chunk_hash, file_id, file_offset, length) VALUES "
		args := make([]interface{}, 0, len(batch)*4)
		for j, cf := range batch {
			if j > 0 {
				query += ", "
			}
			query += "(?, ?, ?, ?)"
			args = append(args, cf.ChunkHash, cf.FileID, cf.FileOffset, cf.Length)
		}
		query += " ON CONFLICT(chunk_hash, file_id) DO NOTHING"

		var err error
		if tx != nil {
			_, err = tx.ExecContext(ctx, query, args...)
		} else {
			_, err = r.db.ExecWithLog(ctx, query, args...)
		}
		if err != nil {
			return fmt.Errorf("batch inserting chunk_files: %w", err)
		}
	}

	return nil
}