//go:build windows

package compose

import (
	"context"
	"errors"
	"os"
	"os/exec"
	"strconv"
	"strings"
	"testing"
	"time"

	"golang.org/x/sys/windows"
)

func TestOwnedProcessUsesCreationTimeJobAttribute(t *testing.T) {
	if procThreadAttributeJobList == 0 {
		t.Fatal("owned Windows process must carry a creation-time job-list attribute")
	}
	cmd := exec.Command("cmd.exe")
	configureOwnedProcess(cmd)
	if cmd.SysProcAttr != nil && cmd.SysProcAttr.CreationFlags&windows.CREATE_SUSPENDED != 0 {
		t.Fatal("owned Windows process must not rely on a post-start assignment race")
	}
}

func TestOwnedJobPolicyKillsDescendantsOnClose(t *testing.T) {
	if windows.JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE == 0 {
		t.Fatal("owned job must use kill-on-close policy")
	}
}

// TestWindowsProcessHelper is both a test helper and the child process used by the runtime
// ownership regression below. The grandchild records its PID before the parent can exit. The
// parent then either exits, blocks for cancellation, or overflows stdout.
func TestWindowsProcessHelper(t *testing.T) {
	mode := os.Getenv("THOTHCTL_WINDOWS_HELPER")
	if mode == "" {
		return
	}
	pidFile := os.Getenv("THOTHCTL_WINDOWS_PID_FILE")
	releaseFile := os.Getenv("THOTHCTL_WINDOWS_RELEASE_FILE")
	if mode == "grandchild" {
		if err := os.WriteFile(pidFile, []byte(strconv.Itoa(os.Getpid())), 0o600); err != nil {
			t.Fatal(err)
		}
		for {
			time.Sleep(time.Hour)
		}
	}
	child := exec.Command(os.Args[0], "-test.run=TestWindowsProcessHelper", "--")
	child.Env = append(os.Environ(),
		"THOTHCTL_WINDOWS_HELPER=grandchild",
		"THOTHCTL_WINDOWS_PID_FILE="+pidFile,
	)
	if err := child.Start(); err != nil {
		t.Fatal(err)
	}
	waitForWindowsPIDFile(t, pidFile)
	waitForWindowsReleaseFile(t, releaseFile)
	if mode == "exit" {
		return
	}
	if mode == "cancel" {
		for {
			time.Sleep(time.Hour)
		}
	}
	for {
		_, _ = os.Stdout.Write([]byte("overflow\n"))
	}
}

func waitForWindowsPIDFile(t *testing.T, path string) {
	t.Helper()
	deadline := time.Now().Add(5 * time.Second)
	for time.Now().Before(deadline) {
		contents, err := os.ReadFile(path)
		if err == nil {
			pid, parseErr := strconv.Atoi(strings.TrimSpace(string(contents)))
			if parseErr == nil && pid > 0 {
				return
			}
		}
		time.Sleep(time.Millisecond)
	}
	t.Fatalf("grandchild PID was not recorded in %s", path)
}

func waitForWindowsReleaseFile(t *testing.T, path string) {
	t.Helper()
	deadline := time.Now().Add(5 * time.Second)
	for time.Now().Before(deadline) {
		if _, err := os.Stat(path); err == nil {
			return
		}
		time.Sleep(time.Millisecond)
	}
	t.Fatalf("test did not release Windows helper via %s", path)
}

func openWindowsProcessForTest(t *testing.T, pid int) windows.Handle {
	t.Helper()
	const access = windows.SYNCHRONIZE | windows.PROCESS_QUERY_LIMITED_INFORMATION
	handle, err := windows.OpenProcess(access, false, uint32(pid))
	if err != nil {
		t.Fatalf("OpenProcess(%d): %v", pid, err)
	}
	return handle
}

func assertWindowsProcessTerminated(t *testing.T, handle windows.Handle, pid int) {
	t.Helper()
	const stillActive = 259
	status, err := windows.WaitForSingleObject(handle, uint32((5*time.Second)/time.Millisecond))
	if err != nil {
		t.Fatalf("WaitForSingleObject(%d): %v", pid, err)
	}
	if status != windows.WAIT_OBJECT_0 {
		t.Fatalf("WaitForSingleObject(%d) = %#x, want signaled terminated process", pid, status)
	}
	var exitCode uint32
	if err := windows.GetExitCodeProcess(handle, &exitCode); err != nil {
		t.Fatalf("GetExitCodeProcess(%d): %v", pid, err)
	}
	if exitCode == stillActive {
		t.Fatalf("GetExitCodeProcess(%d) still reports STILL_ACTIVE", pid)
	}
}

func TestOwnedProcessTerminatesDescendantOnOverflowCancelAndParentExit(t *testing.T) {
	for _, mode := range []string{"overflow", "cancel", "exit"} {
		t.Run(mode, func(t *testing.T) {
			pidFile, err := os.CreateTemp("", "thothctl-windows-grandchild-*.pid")
			if err != nil {
				t.Fatal(err)
			}
			pidPath := pidFile.Name()
			_ = pidFile.Close()
			_ = os.Remove(pidPath)
			defer os.Remove(pidPath)
			releaseFile, err := os.CreateTemp("", "thothctl-windows-release-*")
			if err != nil {
				t.Fatal(err)
			}
			releasePath := releaseFile.Name()
			_ = releaseFile.Close()
			_ = os.Remove(releasePath)
			defer os.Remove(releasePath)
			t.Setenv("THOTHCTL_WINDOWS_HELPER", mode)
			t.Setenv("THOTHCTL_WINDOWS_PID_FILE", pidPath)
			t.Setenv("THOTHCTL_WINDOWS_RELEASE_FILE", releasePath)
			ctx := context.Background()
			var cancel context.CancelFunc
			if mode == "cancel" {
				ctx, cancel = context.WithCancel(ctx)
				defer cancel()
			}
			result := make(chan error, 1)
			go func() {
				_, runErr := runBoundedWindows(ctx, os.Args[0], []string{"-test.run=TestWindowsProcessHelper", "--"}, nil, CaptureLimits{StdoutBytes: 1024, StderrBytes: 1024})
				result <- runErr
			}()

			waitForWindowsPIDFile(t, pidPath)
			contents, err := os.ReadFile(pidPath)
			if err != nil {
				t.Fatal(err)
			}
			pid, err := strconv.Atoi(strings.TrimSpace(string(contents)))
			if err != nil {
				t.Fatal(err)
			}
			handle := openWindowsProcessForTest(t, pid)
			defer windows.CloseHandle(handle)
			if err := os.WriteFile(releasePath, []byte("release"), 0o600); err != nil {
				t.Fatal(err)
			}
			if mode == "cancel" {
				cancel()
			}
			select {
			case runErr := <-result:
				if mode == "overflow" && !errors.Is(runErr, ErrOutputLimit) {
					t.Fatalf("overflow error = %v, want ErrOutputLimit", runErr)
				}
				if mode == "cancel" && !errors.Is(runErr, context.Canceled) {
					t.Fatalf("cancel error = %v, want context.Canceled", runErr)
				}
			case <-time.After(5 * time.Second):
				t.Fatal("owned process did not terminate")
			}
			assertWindowsProcessTerminated(t, handle, pid)
		})
	}
}