package stario

import (
	"context"
	"errors"
	"os"

	"golang.org/x/term"
)

// ErrTerminalNotTTY reports that terminal-only input was requested from a
// non-terminal stdin.
var ErrTerminalNotTTY = errors.New("terminal input requires a tty")

var terminalCheckFunc = term.IsTerminal

// IsTerminal reports whether os.Stdin is attached to a terminal.
func IsTerminal() bool {
	return IsTerminalFile(os.Stdin)
}

// IsTerminalFD reports whether fd is attached to a terminal.
func IsTerminalFD(fd int) bool {
	return terminalCheckFunc(fd)
}

// IsTerminalFile reports whether file is attached to a terminal.
func IsTerminalFile(file *os.File) bool {
	if file == nil {
		return false
	}
	return IsTerminalFD(int(file.Fd()))
}

// ReadPasswordContext reads one password-style line from the terminal.
//
// It returns ErrTerminalNotTTY when stdin is not a terminal. If ctx is canceled
// while waiting for input, this function returns ctx.Err() without waiting for
// the underlying terminal read to finish.
func ReadPasswordContext(ctx context.Context, hint string, defaultVal string) (string, error) {
	return ReadPasswordContextWithMask(ctx, hint, defaultVal, "")
}

// ReadPasswordContextWithMask is like ReadPasswordContext but echoes the given
// mask string while the user types.
func ReadPasswordContextWithMask(ctx context.Context, hint string, defaultVal string, mask string) (string, error) {
	if ctx == nil {
		ctx = context.Background()
	}
	if err := ctx.Err(); err != nil {
		return "", err
	}
	if !IsTerminal() {
		return "", ErrTerminalNotTTY
	}
	session, err := rawTerminalSessionFactory(hint, true)
	if err != nil {
		return "", err
	}
	resultCh := make(chan InputMsg, 1)
	go func() {
		defer session.Close()
		resultCh <- rawLineInputSession(session, defaultVal, mask, rawInputSignalReturnError)
	}()
	select {
	case result := <-resultCh:
		return result.String()
	case <-ctx.Done():
		session.Abort()
		<-resultCh
		return "", ctx.Err()
	}
}