const fp = require("lodash/fp");
const _ = require("lodash");

const DatabaseAnalayser = require("../default/DatabaseAnalyser");

/** @returns {Promise<string>} */
async function loadQuery(pool, name) {
  return await pool._nativeModules.fs.readFile(
    pool._nativeModules.path.join(__dirname, name),
    "utf-8"
  );
}

const byTableFilter = table => x =>
  x.pureName == table.pureName && x.schemaName == x.schemaName;

function extractPrimaryKeys(table, pkColumns) {
  const filtered = pkColumns.filter(byTableFilter(table));
  if (filtered.length == 0) return undefined;
  return {
    ..._.pick(filtered[0], ["constraintName", "schemaName", "pureName"]),
    constraintType: "primaryKey",
    columns: filtered.map(fp.pick("columnName"))
  };
}

function extractForeignKeys(table, fkColumns) {
  const grouped = _.groupBy(
    fkColumns.filter(byTableFilter(table)),
    "constraintName"
  );
  return _.keys(grouped).map(constraintName => ({
    constraintName,
    constraintType: "foreignKey",
    ..._.pick(grouped[constraintName][0], [
      "constraintName",
      "schemaName",
      "pureName",
      "refSchemaName",
      "refTableName",
      "updateAction",
      "deleteAction"
    ]),
    columns: grouped[constraintName].map(
      fp.pick(["columnName", "refColumnName"])
    )
  }));
}

class MsSqlAnalyser extends DatabaseAnalayser {
  constructor(pool, driver) {
    super(pool, driver);
  }

  async createQuery(
    resFileName,
    tables = false,
    views = false,
    procedures = false,
    functions = false,
    triggers = false
  ) {
    let res = await loadQuery(this.pool, resFileName);
    res = res.replace("=[OBJECT_ID_CONDITION]", " is not null");
    return res;
  }
  async runAnalysis() {
    const tables = await this.driver.query(
      this.pool,
      await this.createQuery("tables.sql")
    );
    const columns = await this.driver.query(
      this.pool,
      await this.createQuery("columns.sql")
    );
    const pkColumns = await this.driver.query(
      this.pool,
      await this.createQuery("primary_keys.sql")
    );
    const fkColumns = await this.driver.query(
      this.pool,
      await this.createQuery("foreign_keys.sql")
    );

    this.result.tables = tables.rows.map(table => ({
      ...table,
      columns: columns.rows
        .filter(col => col.objectId == table.objectId)
        .map(({ isNullable, isIdentity, ...col }) => ({
          ...col,
          notNull: !isNullable,
          autoIncrement: !!isIdentity
        })),
      primaryKey: extractPrimaryKeys(table, pkColumns.rows),
      foreignKeys: extractForeignKeys(table, fkColumns.rows)
    }));
  }
}

module.exports = MsSqlAnalyser;