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")
	d := fs.Duration("d", time.Second, "interval")
	if err := fs.Parse(os.Args[1:]); err != nil {
		panic(err)
	}

	return with.PSQL(ctx, *c, func(pg *sql.DB) error {
		log.Println("staging...")
		if _, err := pg.ExecContext(ctx, `
	   	DROP TABLE IF EXISTS "pg-pulse";
	   	CREATE TABLE IF NOT EXISTS "pg-pulse" (k TEXT);
	   `); err != nil {
			return err
		}

		log.Println("spamming...")

		var downtime time.Duration
		okc := make(chan bool)
		defer close(okc)
		go func() {
			lastOK := true
			wasOK := time.Now()
			for ok := range okc {
				if isNewlyOK := ok && !lastOK; isNewlyOK {
					downtime += time.Since(wasOK)
				}
				lastOK = ok
				if ok {
					wasOK = time.Now()
				}
			}
		}()
		pushOK := func(v bool) {
			select {
			case okc <- v:
			default:
			}
		}

		n := uint(0)
		isHA := false
		isHA0 := false
		var lostWrites uint
		go with.Every(ctx, 5*time.Second, func() {
			using := ""
			if isHA && isHA0 {
				using = "using ha0"
			} else if isHA && !isHA0 {
				using = "using ha1"
			}
			log.Printf("%v writes (%v lost) (%v down) %s", n, lostWrites, downtime.Round(time.Second), using)
		})

		with.GoEvery(ctx, *d, func() {
			if _, err := pg.ExecContext(ctx, fmt.Sprintf(`
	   		INSERT INTO "pg-pulse" (k) SELECT substr(md5(random()::text), 1, 25)
	   	`)); err != nil {
				pushOK(false)
				log.Println("\n! failed nonzero insert:", err)
			} else {
				n += 1
				pushOK(true)
			}

			ha, ha1 := false, false
			row := pg.QueryRowContext(ctx, `
	   		SELECT
	   			(
	   				SELECT COUNT(*) > 0
	   				FROM pg_replication_slots
	   				WHERE slot_name LIKE 'dpg_%_a_ha__'
	   			) AS is_ha,
	   			(
	   				SELECT COUNT(*) > 0
	   				FROM pg_replication_slots
	   				WHERE slot_name LIKE 'dpg_%_a_ha_0'
	   			) AS is_ha1,
	   			(
	   				SELECT $1 - COUNT(*)
	   				FROM "pg-pulse"
	   			) AS lost_writes
	   	`, n)
			if err := row.Err(); err != nil {
				log.Println("\n! failed getting ha-stuff:", err)
			} else if err := row.Scan(&ha, &ha1, &lostWrites); err != nil {
				log.Println("\n! failed scanning ha-stuff:", err)
			} else {
				isHA = isHA || ha
				isHA0 = isHA && !ha1
			}
		})
		return ctx.Err()
	})
}