/*
Copyright IBM Corp All Rights Reserved.

SPDX-License-Identifier: Apache-2.0
*/

package raft

import (
	"fmt"
	"strconv"
	"sync"
	"time"

	"github.com/onsi/ginkgo/v2"
	"github.com/onsi/gomega"
	"github.com/onsi/gomega/gbytes"
	"github.com/tedsuo/ifrit/ginkgomon_v2"
)

func FindLeader(ordererRunners []*ginkgomon_v2.Runner) int {
	var wg sync.WaitGroup
	wg.Add(len(ordererRunners))

	findLeader := func(runner *ginkgomon_v2.Runner) int {
		gomega.Eventually(runner.Err(), time.Minute, time.Second).Should(gbytes.Say("Raft leader changed: [0-9] -> "))

		idBuff := make([]byte, 1)
		_, err := runner.Err().Read(idBuff)
		gomega.Expect(err).NotTo(gomega.HaveOccurred())

		newLeader, err := strconv.ParseInt(string(idBuff), 10, 32)
		gomega.Expect(err).To(gomega.BeNil())
		return int(newLeader)
	}

	leaders := make(chan int, len(ordererRunners))

	for _, runner := range ordererRunners {
		go func(runner *ginkgomon_v2.Runner) {
			defer ginkgo.GinkgoRecover()
			defer wg.Done()

			for {
				leader := findLeader(runner)
				if leader != 0 {
					leaders <- leader
					break
				}
			}
		}(runner)
	}

	wg.Wait()

	close(leaders)
	firstLeader := <-leaders
	for leader := range leaders {
		if firstLeader != leader {
			ginkgo.Fail(fmt.Sprintf("First leader is %d but saw %d also as a leader", firstLeader, leader))
		}
	}

	return firstLeader
}