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")
	}
}

// TestSuggestedTargetsFileIsRealOrEmpty guards the one-keypress default:
// whatever it offers must actually exist and actually be a file, or pressing
// Enter greets the reader with an error on their very first interaction.
func TestSuggestedTargetsFileIsRealOrEmpty(t *testing.T) {
	got := suggestedTargetsFile()
	if got == "" {
		return // nobody has written a watchlist yet; the prompt explains the format
	}
	info, err := os.Stat(got)
	if err != nil {
		t.Fatalf("suggestedTargetsFile() = %q, which does not exist: %v", got, err)
	}
	if !info.Mode().IsRegular() {
		t.Errorf("suggestedTargetsFile() = %q, which is not a regular file", got)
	}
}

// TestGuidedTargetsAcceptsAFileOrAnAddress covers the two things a person can
// reasonably type at the prompt, and the mistakes they make instead. Every
// rejection has to come back as a sentence for a human, never a Go error
// string, and never as a program that exits and takes the window with it.
func TestGuidedTargetsAcceptsAFileOrAnAddress(t *testing.T) {
	dir := t.TempDir()
	list := filepath.Join(dir, "targets.txt")
	if err := os.WriteFile(list, []byte("# hosts\nweb1 10.0.0.5:443\ndb1 10.0.0.9:5432\n"), 0o644); err != nil {
		t.Fatalf("write: %v", err)
	}

	targets, err := guidedTargets(list)
	if err != nil {
		t.Fatalf("guidedTargets(watchlist) failed: %v", err)
	}
	if len(targets) != 2 || targets[0].Name != "web1" || targets[1].Addr != "10.0.0.9:5432" {
		t.Errorf("guidedTargets(watchlist) = %+v, want the two hosts in the file", targets)
	}

	targets, err = guidedTargets("example.test:22")
	if err != nil {
		t.Fatalf("guidedTargets(address) failed: %v", err)
	}
	if len(targets) != 1 || targets[0].Addr != "example.test:22" {
		t.Errorf("guidedTargets(address) = %+v, want one target for that address", targets)
	}

	for _, bad := range []string{dir, "example.test", filepath.Join(dir, "nope.txt")} {
		if _, err := guidedTargets(bad); err == nil {
			t.Errorf("guidedTargets(%q) succeeded, want a friendly refusal", bad)
		}
	}
}