/**
 * Design documents for _users database.
 * Provides views for efficient user lookups by email and tokens.
 */

import Nano from 'nano';
import { getCouchDB } from './index.js';
import logger from '../logger.js';
import { isNanoError } from '../utils/types.js';

/**
 * Design document for user lookups in _users database.
 */
export const usersDesignDoc = {
  _id: '_design/users',
  views: {
    /**
     * Index users by email address.
     */
    by_email: {
      map: `function(doc) {
        if (doc.type === 'user' && doc.email) {
          emit(doc.email, doc._id);
        }
      }`,
    },
    /**
     * Index users by verification token.
     */
    by_verification_token: {
      map: `function(doc) {
        if (doc.type === 'user' && doc.verificationToken) {
          emit(doc.verificationToken, doc._id);
        }
      }`,
    },
    /**
     * Index users by password reset token.
     */
    by_reset_token: {
      map: `function(doc) {
        if (doc.type === 'user' && doc.passwordResetToken) {
          emit(doc.passwordResetToken, doc._id);
        }
      }`,
    },
  },
  language: 'javascript',
};

/**
 * Apply design documents to _users database.
 * Safe to call multiple times - will only update if changed.
 */
export async function applyUsersDesignDocs(): Promise<void> {
  try {
    const usersDB = getCouchDB().use('_users');

    // Try to get existing design doc
    let existingDoc: Nano.DocumentGetResponse | null = null;
    try {
      existingDoc = await usersDB.get(usersDesignDoc._id);
    } catch (error: unknown) {
      if (isNanoError(error) && error.statusCode !== 404) {
        throw error;
      }
      // Doc doesn't exist, will create new
    }

    // Prepare doc with _rev if updating
    const docToInsert = existingDoc
      ? { ...usersDesignDoc, _rev: existingDoc._rev }
      : usersDesignDoc;

    await usersDB.insert(docToInsert);
    logger.info(
      `Applied design doc ${usersDesignDoc._id} to _users database` +
        (existingDoc ? ' (updated)' : ' (created)')
    );
  } catch (error) {
    logger.error('Error applying _users design documents:', error);
    throw error;
  }
}