const _ = require('lodash');
const stream = require('stream');
const { identify } = require('sql-query-identifier');

const driverBases = require('../frontend/drivers');
const Analyser = require('./Analyser');
const pg = require('pg');
const { createBulkInsertStreamBase, makeUniqueColumnNames } = require('dbgate-tools');

function extractPostgresColumns(result) {
  if (!result || !result.fields) return [];
  const res = result.fields.map(fld => ({
    columnName: fld.name,
  }));
  makeUniqueColumnNames(res);
  return res;
}

function zipDataRow(rowArray, columns) {
  return _.zipObject(
    columns.map(x => x.columnName),
    rowArray
  );
}

async function runStreamItem(client, sql, options) {
  return new Promise((resolve, reject) => {
    const query = new pg.Query({
      text: sql,
      rowMode: 'array',
    });

    let wasHeader = false;

    query.on('row', row => {
      if (!wasHeader) {
        columns = extractPostgresColumns(query._result);
        if (columns && columns.length > 0) {
          options.recordset(columns);
        }
        wasHeader = true;
      }

      options.row(zipDataRow(row, columns));
    });

    query.on('end', () => {
      if (!wasHeader) {
        columns = extractPostgresColumns(query._result);
        if (columns && columns.length > 0) {
          options.recordset(columns);
        }
        wasHeader = true;
      }

      resolve();
    });

    query.on('error', error => {
      console.log('ERROR', error);
      const { message, lineNumber, procName } = error;
      options.info({
        message,
        line: lineNumber,
        procedure: procName,
        time: new Date(),
        severity: 'error',
      });
      resolve();
    });

    client.query(query);
  });
}

/** @type {import('dbgate-types').EngineDriver} */
const drivers = driverBases.map(driverBase => ({
  ...driverBase,
  analyserClass: Analyser,

  async connect({ engine, server, port, user, password, database, databaseUrl, ssl }) {
    let options = null;

    if (engine == 'redshift@dbgate-plugin-postgres') {
      let url = databaseUrl;
      if (url && url.startsWith('jdbc:redshift://')) {
        url = url.substring('jdbc:redshift://'.length);
      }
      if (user && password) {
        url = `postgres://${user}:${password}@${url}`;
      } else if (user) {
        url = `postgres://${user}@${url}`;
      } else {
        url = `postgres://${url}`;
      }

      options = {
        connectionString: url,
      };
    } else {
      options = {
        // connectionString: 'postgres://root@localhost:26257/postgres?sslmode=disabke'
        host: server,
        port,
        user,
        password,
        database: database || 'postgres',
        ssl,
      };
    }

    const client = new pg.Client(options);
    await client.connect();
    return client;
  },
  async close(pool) {
    return pool.end();
  },
  async query(client, sql) {
    if (sql == null) {
      return {
        rows: [],
        columns: [],
      };
    }
    const res = await client.query({ text: sql, rowMode: 'array' });
    const columns = extractPostgresColumns(res);
    return { rows: res.rows.map(row => zipDataRow(row, columns)), columns };
  },
  async stream(client, sql, options) {
    let sqlSplitted;
    try {
      sqlSplitted = identify(sql, { dialect: 'psql', strict: false });
    } catch (e) {
      // workaround
      sqlSplitted = [{ text: sql }];
    }

    for (const sqlItem of sqlSplitted) {
      await runStreamItem(client, sqlItem.text, options);
    }

    options.done();
    // return stream;
  },
  async getVersion(client) {
    const { rows } = await this.query(client, 'SELECT version()');
    const { version } = rows[0];

    const isCockroach = version.toLowerCase().includes('cockroachdb');
    const isRedshift = version.toLowerCase().includes('redshift');
    const isPostgres = !isCockroach && !isRedshift;

    const m = version.match(/([\d\.]+)/);
    let versionText = null;
    if (m) {
      if (isCockroach) versionText = `CockroachDB ${m[1]}`;
      if (isRedshift) versionText = `Redshift ${m[1]}`;
      if (isPostgres) versionText = `PostgreSQL ${m[1]}`;
    }

    return {
      version,
      versionText,
      isPostgres,
      isCockroach,
      isRedshift,
    };
  },
  async readQuery(client, sql, structure) {
    const query = new pg.Query({
      text: sql,
      rowMode: 'array',
    });

    let wasHeader = false;
    let columns = null;

    const pass = new stream.PassThrough({
      objectMode: true,
      highWaterMark: 100,
    });

    query.on('row', row => {
      if (!wasHeader) {
        columns = extractPostgresColumns(query._result);
        pass.write({
          __isStreamHeader: true,
          ...(structure || { columns }),
        });
        wasHeader = true;
      }

      pass.write(zipDataRow(row, columns));
    });

    query.on('end', () => {
      if (!wasHeader) {
        columns = extractPostgresColumns(query._result);
        pass.write({
          __isStreamHeader: true,
          ...(structure || { columns }),
        });
        wasHeader = true;
      }

      pass.end();
    });

    query.on('error', error => {
      console.error(error);
      pass.end();
    });

    client.query(query);

    return pass;
  },
  async writeTable(pool, name, options) {
    // @ts-ignore
    return createBulkInsertStreamBase(this, stream, pool, name, options);
  },
  async listDatabases(client) {
    const { rows } = await this.query(client, 'SELECT datname AS name FROM pg_database WHERE datistemplate = false');
    return rows;
  },
}));

module.exports = drivers;