package input

import (
	"errors"
	"fmt"
	"io"
	"os"
	"syscall"

	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
	"github.com/nspcc-dev/neo-go/pkg/encoding/fixedn"
	"golang.org/x/term"
)

// Terminal is a terminal used for input. If `nil`, stdin is used.
var Terminal *term.Terminal

// ReadWriter combiner reader and writer.
type ReadWriter struct {
	io.Reader
	io.Writer
}

// ReadLine reads a line from the input without trailing '\n'.
func ReadLine(prompt string) (string, error) {
	trm := Terminal
	if trm == nil {
		s, err := term.MakeRaw(int(syscall.Stdin))
		if err != nil {
			return "", err
		}
		defer func() { _ = term.Restore(int(syscall.Stdin), s) }()
		trm = term.NewTerminal(ReadWriter{
			Reader: os.Stdin,
			Writer: os.Stdout,
		}, "")
	}
	return readLine(trm, prompt)
}

func readLine(trm *term.Terminal, prompt string) (string, error) {
	_, err := trm.Write([]byte(prompt))
	if err != nil {
		return "", err
	}
	return trm.ReadLine()
}

// ReadPassword reads the user's password with prompt.
func ReadPassword(prompt string) (string, error) {
	trm := Terminal
	if trm == nil {
		s, err := term.MakeRaw(int(syscall.Stdin))
		if err != nil {
			return "", err
		}
		defer func() { _ = term.Restore(int(syscall.Stdin), s) }()
		trm = term.NewTerminal(ReadWriter{os.Stdin, os.Stdout}, prompt)
	}
	return trm.ReadPassword(prompt)
}

// ConfirmTx asks for a confirmation to send the tx.
func ConfirmTx(w io.Writer, tx *transaction.Transaction) error {
	fmt.Fprintf(w, "Network fee: %s\n", fixedn.Fixed8(tx.NetworkFee))
	fmt.Fprintf(w, "System fee: %s\n", fixedn.Fixed8(tx.SystemFee))
	fmt.Fprintf(w, "Total fee: %s\n", fixedn.Fixed8(tx.NetworkFee+tx.SystemFee))
	ln, err := ReadLine("Relay transaction (y|N)> ")
	if err != nil {
		return err
	}
	if 0 < len(ln) && (ln[0] == 'y' || ln[0] == 'Y') {
		return nil
	}
	return errors.New("cancelled")
}