import {DatabaseConnection} from "./DatabaseConnection";
import {DatabaseColumnDefinition, DatabaseDefinition} from "./DatabaseDefinition";
import {Container} from "../Container/Container";
import {Logger} from "log4js";

export class DatabaseUpdater {
  constructor(private readonly database: DatabaseConnection) {
  }

  public ensureAvaliablity(definitions: Iterable<DatabaseDefinition>) {
    for (const definition of definitions) {
      this.ensureDefinition(definition);
    }
  }

  private ensureDefinition(definition: DatabaseDefinition) {
    if (this.database.hasTable(definition.name)) {
      this.ensureTableColumns(definition);
      return;
    }

    this.createTable(definition);
  }

  private ensureTableColumns(definition: DatabaseDefinition) {
    const DBSQLColumns = this.database.fetchAll<object, { name: string, type: string }>(
      `PRAGMA table_info("${definition.name}")`
    );

    if (!DBSQLColumns) {
      Container.get<Logger>("logger").warn("Request for database columns failed!");
      return;
    }

    const missingColumns = definition.columns.filter(
      (column: DatabaseColumnDefinition) => {
        return !DBSQLColumns.some((dbColumn: DatabaseColumnDefinition) => {
          return column.name === dbColumn.name
        });
      }
    )

    if (missingColumns.length < 1) {
      Container.get<Logger>("logger").debug(`No new columns found for ${definition.name}`)
      return;
    }

    const columnsSQL = missingColumns.map((column: DatabaseColumnDefinition) => {
      const values = [
        "ADD",
        this.getSQLColumnDefinition(column)
      ]

      return values.join(' ');
    }).join(', ');

    const sql = `ALTER TABLE ${definition.name} ${columnsSQL}`;
    console.log(sql);
  }


  private createTable(definition: DatabaseDefinition) {
    const columnsSQL = definition.columns.map((column: DatabaseColumnDefinition) => 
      this.getSQLColumnDefinition(column)
    ).join(', ');

    const sql = `CREATE TABLE IF NOT EXISTS ${definition.name}
                 (
                     ${columnsSQL}
                 )`;
    this.database.execute(sql);
  }
  
  private getSQLColumnDefinition(column: DatabaseColumnDefinition) {
    const values = [
      column.name,
      `${column.type}${column.size ? `(${column.size})` : ''}`,
      column.primaryKey ? `PRIMARY KEY` : '',
      column.notNull ? 'NOT NULL' : '',
      column.autoIncrement ? 'AUTOINCREMENT' : '',
    ];
    
    return values.join(' ')
  }
}