package main

import (
	"context"
	"database/sql"
	"flag"
	"fmt"
	"log"
	"os"
	"time"

	"pg/src/with"

	_ "github.com/lib/pq"
)

func main() {
	if err := with.Context(run); err != nil {
		panic(err)
	}
}

func run(ctx context.Context) error {
	fs := flag.NewFlagSet(os.Args[0], flag.ContinueOnError)
	c := fs.String("c", "postgresql://pulsegres:pulsegres@localhost:15432", "conn string")
	n := fs.Int("n", 12, "mb to generate")
	if err := fs.Parse(os.Args[1:]); err != nil {
		panic(err)
	}

	return with.PSQL(ctx, *c, func(pg *sql.DB) error {
		presently := func() int {
			var n2 int
			if row := pg.QueryRowContext(ctx, `SELECT pg_total_relation_size('fill_with_data')/1024/1024`); row.Err() != nil {
				return 0
			} else if err := row.Scan(&n2); err != nil {
				return 0
			}
			return n2
		}
		report := func() {
			log.Printf("filled %vMiB of requested %vMiB", presently(), *n)
		}

		go with.Every(ctx, 5*time.Second, func() {
			report()
		})

		if _, err := pg.ExecContext(ctx, `
			DROP TABLE IF EXISTS fill_with_data;
			CREATE TABLE IF NOT EXISTS fill_with_data(x BIGINT, y DOUBLE PRECISION, z DOUBLE PRECISION);
		`); err != nil {
			return fmt.Errorf("failed initial table setup: %w", err)
		}

		// https://gist.github.com/ololobus/5b25c432f208d7eb31051a5f238dffff
		// 2e6=1GB, so 2e6/8=12MB
		for i := presently(); i < (*n)/12; i++ {
			for ctx.Err() == nil {
				if _, err := pg.ExecContext(ctx, `
			   	INSERT INTO fill_with_data (x, y, z)
			   	SELECT ROUND(RANDOM()), RANDOM(), RANDOM()
			   	FROM generate_series(1, 2e6/8)
			   `); err != nil {
					return fmt.Errorf("failed lo_from_bytea: %w", err)
				} else {
					break
				}
				select {
				case <-ctx.Done():
					return ctx.Err()
				default:
				}
			}
		}

		report()
		return nil
	})
}