import {
    Kysely,
    Migrator,
    PostgresDialect,
    FileMigrationProvider
} from 'npm:kysely'

/// <reference types="npm:@types/pg" />
import pg from "npm:pg";
import { Database } from "./scheme.ts"
import { CompiledConfig } from "../cfg/config.ts";

export type SetupDbOutput = {
    pool: pg.Pool,
    db: Kysely<Database>,
}
export const setupDB = async (cfg: CompiledConfig): Promise<SetupDbOutput> => {
    console.log("creating db instance: ", cfg.pgPoolCfg)
    const pool = new pg.Pool(cfg.pgPoolCfg)
    const dialect = new PostgresDialect({ pool })
    const db = new Kysely<Database>({ dialect })

    if (cfg.migrationCfg?.applyMigrations) {
        console.log("applying db migrations", cfg.migrationCfg.migrationsPath)
        const migrator = new Migrator({
            db,
            provider: new FileMigrationProvider({
                fs: {
                    readdir(path) {
                        return Promise.resolve(
                            [...Deno.readDirSync(path)].map((file) => file.name)
                        )
                    },
                },
                path: {
                    join(...path) {
                        return path.join('/')
                    },
                },
                migrationFolder: cfg.migrationCfg.migrationsPath,
            }),
            allowUnorderedMigrations: true
        })

        const { error, results } = await migrator.migrateToLatest()

        results?.forEach((it) => {
          if (it.status === 'Success') {
            console.log(`migration "${it.migrationName}" was executed successfully`)
          } else if (it.status === 'Error') {
            console.error(`failed to execute migration "${it.migrationName}"`)
          }
        })
      
        if (error) {
          console.error('failed to migrate')
          console.error(error)
          throw error
        }
    }

    return { pool, db }
}