package db

import (
	"context"
	"fmt"
	"math"
	"strconv"
	"strings"
	"time"

	"github.com/jackc/pgx/v5"

	"github.com/netbirdio/netbird/util"
)

const (
	transactionTimeoutEnv = "NB_STORE_TRANSACTION_TIMEOUT"
	statementTimeoutEnv   = "NB_STORE_STATEMENT_TIMEOUT"
)

// sessionTimeouts sets the configured timeouts on each new Postgres session with
// SET, since poolers such as PgBouncer reject them as startup parameters.
func sessionTimeouts() func(context.Context, *pgx.Conn) error {
	var settings []string
	if d := util.DurationFromEnv(statementTimeoutEnv, 0); d > 0 {
		settings = append(settings, "SET statement_timeout = "+postgresMillis(d))
	}
	if d := util.DurationFromEnv(transactionTimeoutEnv, defaultTransactionTimeout); d > 0 {
		settings = append(settings, "SET idle_in_transaction_session_timeout = "+postgresMillis(d))
	}
	query := strings.Join(settings, "; ")

	return func(ctx context.Context, conn *pgx.Conn) error {
		if query == "" {
			return nil
		}
		if _, err := conn.Exec(ctx, query); err != nil {
			return fmt.Errorf("set session timeouts: %w", err)
		}
		return nil
	}
}

// postgresMillis converts d to milliseconds for a Postgres timeout, rounding up
// so a positive d never becomes 0 (disabled) and capping at the server maximum.
func postgresMillis(d time.Duration) string {
	ms := d.Milliseconds()
	if d%time.Millisecond != 0 {
		ms++
	}
	return strconv.FormatInt(min(ms, math.MaxInt32), 10)
}