package main

import (
	"os"
	"path/filepath"
	"testing"
)

// TestIsCharDeviceRejectsNonConsoles pins down the half of the check that can
// be tested without a terminal: a pipe, a regular file and a closed handle
// must all read as "not a console", because each of them means something other
// than a person waiting at a keyboard.
//
// Getting this wrong in this direction is the dangerous one: it would drop a
// script or a build pipeline into an interactive prompt and hang it forever.
func TestIsCharDeviceRejectsNonConsoles(t *testing.T) {
	r, w, err := os.Pipe()
	if err != nil {
		t.Fatalf("pipe: %v", err)
	}
	defer r.Close()
	defer w.Close()

	tmp, err := os.CreateTemp(t.TempDir(), "out")
	if err != nil {
		t.Fatalf("temp file: %v", err)
	}
	defer tmp.Close()

	devNull, err := os.Open(os.DevNull)
	if err != nil {
		t.Fatalf("open %s: %v", os.DevNull, err)
	}
	defer devNull.Close()

	for _, tc := range []struct {
		name string
		file *os.File
		want bool
	}{
		{"read end of a pipe", r, false},
		{"write end of a pipe", w, false},
		{"regular file", tmp, false},
		// os.DevNull IS a character device on Unix, so this case documents a
		// real limitation rather than asserting a value that differs by
		// platform: `prog < /dev/null` on Unix looks interactive on stdin.
		// It is harmless, because stdout must ALSO be a console, and a script
		// redirecting stdin almost always redirects stdout too.
	} {
		if got := isCharDevice(tc.file); got != tc.want {
			t.Errorf("isCharDevice(%s) = %v, want %v", tc.name, got, tc.want)
		}
	}
	_ = devNull
}

// TestIsCharDeviceHandlesAClosedFile makes sure a handle we cannot stat is
// treated as "not a console" rather than panicking or defaulting to true.
func TestIsCharDeviceHandlesAClosedFile(t *testing.T) {
	f, err := os.CreateTemp(t.TempDir(), "closed")
	if err != nil {
		t.Fatalf("temp file: %v", err)
	}
	f.Close()
	if isCharDevice(f) {
		t.Error("isCharDevice(closed file) = true, want false")
	}
}

// TestInteractiveConsoleNeedsBothEnds asserts the AND: one console end is not
// enough. Under `go test` stdout is not a terminal, so this must be false.
func TestInteractiveConsoleNeedsBothEnds(t *testing.T) {
	if interactiveConsole() {
		t.Error("interactiveConsole() = true under `go test`, where output is captured; " +
			"the guided prompt would hang any non-interactive run")
	}
}

// TestSuggestedVideoIsRealOrEmpty guards the one-keypress default: whatever it
// offers must actually exist and be a file videomend can open, or pressing
// Enter greets the reader with an error on their very first interaction.
func TestSuggestedVideoIsRealOrEmpty(t *testing.T) {
	got := suggestedVideo()
	if got == "" {
		return // no video lying around; the prompt asks for one instead
	}
	info, err := os.Stat(got)
	if err != nil {
		t.Fatalf("suggestedVideo() = %q, which does not exist: %v", got, err)
	}
	if info.IsDir() {
		t.Errorf("suggestedVideo() = %q, which is a directory, not a video file", got)
	}
	if !isVideoName(got) {
		t.Errorf("suggestedVideo() = %q, which is not a container videomend reads", got)
	}
}

// TestNewestVideoInIgnoresNonVideos makes sure the default never lands on a
// text file that happens to be sitting in the same folder.
func TestNewestVideoInIgnoresNonVideos(t *testing.T) {
	dir := t.TempDir()
	for _, name := range []string{"notes.txt", "archive.zip", "empty.mp4"} {
		if err := os.WriteFile(filepath.Join(dir, name), nil, 0o644); err != nil {
			t.Fatalf("write %s: %v", name, err)
		}
	}
	if got := newestVideoIn(dir); got != "" {
		t.Errorf("newestVideoIn(folder of non-videos and an empty .mp4) = %q, want \"\"", got)
	}
	real := filepath.Join(dir, "clip.mov")
	if err := os.WriteFile(real, []byte("not really a movie, but not empty"), 0o644); err != nil {
		t.Fatalf("write clip.mov: %v", err)
	}
	if got := newestVideoIn(dir); got != real {
		t.Errorf("newestVideoIn(...) = %q, want %q", got, real)
	}
}