package proc

import (
	"context"
	"errors"
	"net/http"
	"net/http/httptest"
	"sync"
	"testing"
	"time"
)

func TestProcessDoneBroadcastsAndExitErrorPersists(t *testing.T) {
	m := New(nil)
	p, err := m.Start(context.Background(), Spec{
		Name: "exit",
		Args: []string{"sh", "-c", "exit 7"},
	})
	if err != nil {
		t.Fatalf("Start() error = %v", err)
	}

	waitForDone(t, p.Done)
	waitForDone(t, p.Done)

	first := p.ExitErr()
	second := p.ExitErr()
	if first == nil {
		t.Fatal("ExitErr() = nil, want exit error")
	}
	if first.Error() != second.Error() {
		t.Fatalf("ExitErr() changed: first %q, second %q", first, second)
	}
}

func TestProcessExitErrorIsRepeatable(t *testing.T) {
	want := errors.New("exited")
	done := make(chan struct{})
	p := &Process{Done: done, done: done}
	p.finish(want)

	for i := 0; i < 2; i++ {
		got, exited := processExitError(p)
		if !exited {
			t.Fatalf("call %d: exited = false, want true", i+1)
		}
		if !errors.Is(got, want) {
			t.Fatalf("call %d: error = %v, want %v", i+1, got, want)
		}
	}
}

func TestStopUntracksProcessAndIsIdempotent(t *testing.T) {
	m := New(nil)
	p, err := m.Start(context.Background(), Spec{
		Name: "stop",
		Args: []string{"sh", "-c", "trap 'exit 0' TERM; while :; do sleep 1; done"},
	})
	if err != nil {
		t.Fatalf("Start() error = %v", err)
	}
	if got := len(m.procs); got != 1 {
		t.Fatalf("tracked processes = %d, want 1", got)
	}

	m.Stop(p)
	m.Stop(p)
	if got := len(m.procs); got != 0 {
		t.Fatalf("tracked processes after Stop = %d, want 0", got)
	}
	waitForDone(t, p.Done)
	m.StopAll()
}

func TestConcurrentStopAndStopAllDrainEveryProcess(t *testing.T) {
	m := New(nil)
	processes := make([]*Process, 0, 4)
	for i := 0; i < 4; i++ {
		p, err := m.Start(context.Background(), Spec{
			Name: "concurrent-stop",
			Args: []string{"sh", "-c", "trap 'exit 0' TERM; while :; do sleep 1; done"},
		})
		if err != nil {
			t.Fatalf("Start() error = %v", err)
		}
		processes = append(processes, p)
	}

	var wg sync.WaitGroup
	wg.Add(2)
	go func() {
		defer wg.Done()
		m.Stop(processes[0])
	}()
	go func() {
		defer wg.Done()
		m.StopAll()
	}()
	wg.Wait()

	if got := len(m.procs); got != 0 {
		t.Fatalf("tracked processes after concurrent drain = %d, want 0", got)
	}
	for _, process := range processes {
		waitForDone(t, process.Done)
	}
}

func TestAwaitReadyDoesNotConsumeCompletion(t *testing.T) {
	server := httptest.NewServer(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {}))
	defer server.Close()

	want := errors.New("exited during readiness")
	done := make(chan struct{})
	p := &Process{
		Name: "exit",
		Done: done,
		done: done,
		spec: Spec{
			ReadyURL:     server.URL,
			ReadyTimeout: time.Second,
		},
	}
	p.finish(want)

	err := New(nil).awaitReady(context.Background(), p)
	if !errors.Is(err, want) {
		t.Fatalf("awaitReady() error = %v, want %v", err, want)
	}
	waitForDone(t, p.Done)
	if !errors.Is(p.ExitErr(), want) {
		t.Fatalf("ExitErr() = %v, want %v", p.ExitErr(), want)
	}
}

func waitForDone(t *testing.T, done <-chan struct{}) {
	t.Helper()
	select {
	case <-done:
	case <-time.After(time.Second):
		t.Fatal("timed out waiting for process completion")
	}
}