import { writeAttachmentToDisk } from "../attachments-store.js";
import type { DrizzleDb } from "../db-connection.js";
import { getSqliteFrom } from "../db-connection.js";

/**
 * Backfill existing inline (base64-in-DB) attachments to disk.
 *
 * Finds attachment rows that have non-empty data_base64 but no file_path,
 * writes each one to disk, and updates the row to store the file path
 * while clearing the inline data.
 *
 * Processes in batches of 50 to avoid holding large amounts of base64 data
 * in memory at once.
 */
export function migrateBackfillInlineAttachmentsToDisk(
  database: DrizzleDb,
): void {
  const raw = getSqliteFrom(database);
  const BATCH_SIZE = 50;
  let totalMigrated = 0;

  for (;;) {
    const rows = raw
      .query(
        `SELECT id, original_filename, data_base64 FROM attachments
         WHERE (file_path IS NULL OR file_path = '')
           AND data_base64 != ''
           AND length(data_base64) > 0
         LIMIT ?`,
      )
      .all(BATCH_SIZE) as Array<{
      id: string;
      original_filename: string;
      data_base64: string;
    }>;

    if (rows.length === 0) {
      break;
    }

    for (const row of rows) {
      const filePath = writeAttachmentToDisk(
        row.data_base64,
        row.original_filename,
      );
      raw
        .query(
          `UPDATE attachments SET file_path = ?, data_base64 = '' WHERE id = ?`,
        )
        .run(filePath, row.id);
    }

    totalMigrated += rows.length;
  }

  if (totalMigrated > 0) {
    // Log is intentionally not imported to keep migration self-contained;
    // the checkpoint value records completion.
    console.log(`Migrated ${totalMigrated} inline attachments to disk`);
  }
}

/**
 * Reverse: no-op.
 *
 * The forward migration moved attachment data from inline base64 in the
 * database to on-disk files and cleared the dataBase64 column. The original
 * base64 data has been deleted from the DB, and re-reading it from disk
 * back into the database would be unreliable (file paths may have changed,
 * disk files may have been cleaned up). The on-disk files remain intact
 * and functional.
 */
export function migrateBackfillInlineAttachmentsToDiskDown(
  _database: DrizzleDb,
): void {
  // No-op — see comment above.
}