package main

import (
	"context"
	"errors"
	"strings"
	"sync"
	"testing"
)

func TestWorkerMemprosesJob(t *testing.T) {
	jobs := make(chan Job, 1)
	results := make(chan Result, 1)
	var wg sync.WaitGroup

	fn := func(job Job) (string, error) {
		return strings.ToUpper(job.Payload), nil
	}

	wg.Add(1)
	go worker(context.Background(), jobs, results, fn, &wg)

	jobs <- Job{ID: 7, Payload: "tugas-07"}
	close(jobs)

	res := <-results
	wg.Wait()

	if res.JobID != 7 {
		t.Errorf("JobID hasil = %d, ingin 7", res.JobID)
	}
	if res.Output != "TUGAS-07" {
		t.Errorf("Output hasil = %q, ingin TUGAS-07", res.Output)
	}
	if res.Err != nil {
		t.Errorf("Err hasil = %v, ingin nil", res.Err)
	}
}

func TestWorkerJobGagal(t *testing.T) {
	jobs := make(chan Job, 1)
	results := make(chan Result, 1)
	var wg sync.WaitGroup

	galatUji := errors.New("payload kosong")
	fn := func(job Job) (string, error) {
		return "", galatUji
	}

	wg.Add(1)
	go worker(context.Background(), jobs, results, fn, &wg)

	jobs <- Job{ID: 1, Payload: ""}
	close(jobs)

	res := <-results
	wg.Wait()

	if res.Err == nil {
		t.Fatal("Err hasil = nil, ingin galat")
	}
	if !errors.Is(res.Err, galatUji) {
		t.Errorf("Err hasil = %v, ingin galat uji", res.Err)
	}
	if res.Output != "" {
		t.Errorf("Output hasil = %q, ingin string kosong saat gagal", res.Output)
	}
}

func TestWorkerBerhentiSaatContextDibatalkan(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	// Batalkan sebelum worker sempat mengambil job apa pun.
	cancel()

	jobs := make(chan Job, 1)
	results := make(chan Result, 1)
	var wg sync.WaitGroup

	fn := func(job Job) (string, error) {
		return strings.ToUpper(job.Payload), nil
	}

	wg.Add(1)
	go worker(ctx, jobs, results, fn, &wg)

	jobs <- Job{ID: 1, Payload: "tugas-01"}
	close(jobs)
	wg.Wait()

	select {
	case res := <-results:
		t.Errorf("worker memproses job setelah pembatalan: %+v", res)
	default:
		// Tidak ada hasil: worker keluar tanpa memproses apa pun.
	}
}

func TestWorkerChannelTertutupMenghentikanWorker(t *testing.T) {
	jobs := make(chan Job, 2)
	results := make(chan Result, 2)
	var wg sync.WaitGroup

	fn := func(job Job) (string, error) {
		return strings.ToUpper(job.Payload), nil
	}

	wg.Add(1)
	go worker(context.Background(), jobs, results, fn, &wg)

	jobs <- Job{ID: 1, Payload: "satu"}
	jobs <- Job{ID: 2, Payload: "dua"}
	close(jobs)
	wg.Wait()

	if len(results) != 2 {
		t.Fatalf("jumlah hasil = %d, ingin 2", len(results))
	}
}