//go:build linux

package lagoon

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"strings"
	"sync"
	"syscall"
	"testing"
	"time"
	"unsafe"

	"git.golem15.com/golem15/summercms/modules/bonfire"
)

// ptyOutput collects what the program writes to a pseudo-terminal.
type ptyOutput struct {
	mu  sync.Mutex
	buf bytes.Buffer
}

func (p *ptyOutput) String() string {
	p.mu.Lock()
	defer p.mu.Unlock()
	return p.buf.String()
}

// openPTY opens a pseudo-terminal pair: the slave is a terminal for the
// console (stdin and stdout), input written to the master reaches the
// slave's stdin, and everything the slave prints is collected.
func openPTY(t *testing.T) (master, slave *os.File, output *ptyOutput) {
	t.Helper()
	m, err := os.OpenFile("/dev/ptmx", os.O_RDWR|syscall.O_NOCTTY, 0)
	if err != nil {
		t.Fatalf("open /dev/ptmx: %v", err)
	}
	var unlock int32
	if _, _, e := syscall.Syscall(syscall.SYS_IOCTL, m.Fd(), syscall.TIOCSPTLCK, uintptr(unsafe.Pointer(&unlock))); e != 0 {
		t.Fatalf("unlock pty: %v", e)
	}
	var n uint32
	if _, _, e := syscall.Syscall(syscall.SYS_IOCTL, m.Fd(), syscall.TIOCGPTN, uintptr(unsafe.Pointer(&n))); e != 0 {
		t.Fatalf("pty number: %v", e)
	}
	s, err := os.OpenFile(fmt.Sprintf("/dev/pts/%d", n), os.O_RDWR|syscall.O_NOCTTY, 0)
	if err != nil {
		t.Fatalf("open pty slave: %v", err)
	}
	output = &ptyOutput{}
	done := make(chan struct{})
	go func() {
		defer close(done)
		buf := make([]byte, 4096)
		for {
			n, err := m.Read(buf)
			output.mu.Lock()
			output.buf.Write(buf[:n])
			output.mu.Unlock()
			if err != nil {
				return
			}
		}
	}()
	t.Cleanup(func() {
		_ = s.Close()
		_ = m.Close()
		<-done
	})
	return m, s, output
}

// waitFor waits until the pty output contains want.
func waitFor(t *testing.T, output *ptyOutput, want string) {
	t.Helper()
	for range 200 {
		if strings.Contains(output.String(), want) {
			return
		}
		<-time.After(10 * time.Millisecond)
	}
	t.Fatalf("pty output lacks %q:\n%s", want, output.String())
}

// runOnPTY runs probe:confirm with args on a fresh pseudo-terminal after
// typing answer, and returns the exit code and the terminal output.
func runOnPTY(t *testing.T, env, answer string, args ...string) (int, *ptyOutput) {
	t.Helper()
	master, slave, output := openPTY(t)
	if _, err := master.Write([]byte(answer)); err != nil {
		t.Fatal(err)
	}
	root, err := bonfire.NewRootIO("acme", []bonfire.Command{probeConfirm(envApp(t, env, ""))}, slave, slave, slave)
	if err != nil {
		t.Fatal(err)
	}
	// --no-ansi keeps the line prompt (huh needs a terminal size).
	code := bonfire.Execute(context.Background(), root, append([]string{"--no-ansi", "probe:confirm"}, args...))
	return code, output
}

// TestConfirmProductionInteractiveNo: on an interactive terminal in
// production the question is asked; "n" or an empty answer prints the
// cancel line and exits 1 without an error block (Reported); "y" proceeds.
func TestConfirmProductionInteractiveNo(t *testing.T) {
	for _, answer := range []string{"n\n", "\n", "no\n"} {
		code, output := runOnPTY(t, "production", answer)
		if code != bonfire.ExitFailure {
			t.Fatalf("answer %q: exit %d\n%s", answer, code, output.String())
		}
		waitFor(t, output, "Migration cancelled.")
		got := output.String()
		if !strings.Contains(got, "Apply 3 migrations to the production database? [y/N]") {
			t.Errorf("answer %q: question not asked:\n%s", answer, got)
		}
		if strings.Contains(got, "ERROR") || strings.Contains(got, "proceeded") {
			t.Errorf("answer %q: error block or the step ran:\n%s", answer, got)
		}
	}
	code, output := runOnPTY(t, "production", "y\n")
	if code != bonfire.ExitOK {
		t.Fatalf("answer y: exit %d\n%s", code, output.String())
	}
	waitFor(t, output, "proceeded")
}

// TestForceSkipsConfirm: --force, -n and any environment other than
// production proceed on an interactive terminal without asking (the typed
// "n" is never read).
func TestForceSkipsConfirm(t *testing.T) {
	for name, tc := range map[string]struct {
		env  string
		args []string
	}{
		"--force":     {"production", []string{"--force"}},
		"-n":          {"production", []string{"-n"}},
		"staging":     {"staging", nil},
		"development": {"development", nil},
	} {
		code, output := runOnPTY(t, tc.env, "n\n", tc.args...)
		if code != bonfire.ExitOK {
			t.Fatalf("%s: exit %d\n%s", name, code, output.String())
		}
		waitFor(t, output, "proceeded")
		if strings.Contains(output.String(), "[y/N]") {
			t.Errorf("%s: the question was asked:\n%s", name, output.String())
		}
	}
}