terminal_windows.go

package devlog

import (
	"io"
	"os"

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

// IsColorTerminal checks if the given writer is a terminal with ANSI color support.
// It respects [NO_COLOR], [FORCE_COLOR] and TERM=dumb environment variables.
//
// [NO_COLOR]: https://no-color.org/
// [FORCE_COLOR]: https://force-color.org/
func IsColorTerminal(output io.Writer) bool {
	if os.Getenv("NO_COLOR") != "" {
		return false
	}
	if os.Getenv("FORCE_COLOR") != "" {
		return true
	}
	if os.Getenv("TERM") == "dumb" {
		return false
	}

	if output == nil {
		return false
	}

	file, isFile := output.(*os.File)
	if !isFile {
		return false
	}

	console := windows.Handle(file.Fd())
	var consoleMode uint32
	if err := windows.GetConsoleMode(console, &consoleMode); err != nil {
		return false
	}

	var wantedMode uint32 = windows.ENABLE_PROCESSED_OUTPUT | windows.ENABLE_VIRTUAL_TERMINAL_PROCESSING
	if (consoleMode & wantedMode) == wantedMode {
		return true
	}

	consoleMode |= wantedMode
	if err := windows.SetConsoleMode(console, consoleMode); err != nil {
		return false
	}

	return true
}