package mnemonic_test

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

	"github.com/stretchr/testify/require"
	"sneak.berlin/go/keyfunc/internal/mnemonic"
)

// Two more mnemonics that pass the checksum, so a test can tell which
// source an answer came from.
const (
	fromCommandVariable = "legal winner thank year wave sausage worth " +
		"useful legal winner thank yellow"
	fromVariable = "letter advice cage absurd amount doctor acoustic " +
		"avoid letter advice cage above"
)

// example returns the mnemonic every BIP-39 document uses to show its
// test vectors: eleven abandons and about.
func example() string {
	return strings.Repeat("abandon ", 11) + "about"
}

// broken returns a mnemonic whose last word does not match the rest.
func broken() string {
	return strings.TrimSpace(strings.Repeat("abandon ", 12))
}

// prints builds a shell command that writes the given words padded
// with spaces, so the test also shows that the padding is dropped.
func prints(words string) string {
	return "printf '  %s  \\n' '" + words + "'"
}

func TestTheCommandOnTheCommandLineWins(t *testing.T) {
	t.Setenv(mnemonic.CommandVariable, prints(fromCommandVariable))
	t.Setenv(mnemonic.Variable, fromVariable)

	words, err := mnemonic.Read(t.Context(), prints(example()))
	require.NoError(t, err)
	require.Equal(t, example(), words)
}

func TestTheCommandInTheEnvironmentComesNext(t *testing.T) {
	t.Setenv(mnemonic.CommandVariable, prints(fromCommandVariable))
	t.Setenv(mnemonic.Variable, fromVariable)

	words, err := mnemonic.Read(t.Context(), "")
	require.NoError(t, err)
	require.Equal(t, fromCommandVariable, words)
}

func TestTheMnemonicInTheEnvironmentComesLast(t *testing.T) {
	t.Setenv(mnemonic.CommandVariable, "")
	t.Setenv(mnemonic.Variable, "  "+fromVariable+"  ")

	words, err := mnemonic.Read(t.Context(), "")
	require.NoError(t, err)
	require.Equal(t, fromVariable, words)
}

func TestTheMnemonicIsNotHandedToTheCommand(t *testing.T) {
	const marker = "KEYFUNC_TEST_MARKER"

	t.Setenv(mnemonic.CommandVariable, prints(fromCommandVariable))
	t.Setenv(mnemonic.Variable, fromVariable)
	t.Setenv(marker, "reaches the command")

	path := filepath.Join(t.TempDir(), "environment")

	words, err := mnemonic.Read(
		t.Context(), "env > '"+path+"'; "+prints(example()),
	)
	require.NoError(t, err)
	require.Equal(t, example(), words)

	//nolint:gosec // the path is a temporary file of the test's own
	content, err := os.ReadFile(path)
	require.NoError(t, err)

	environment := string(content)
	require.NotContains(t, environment, mnemonic.Variable+"=")
	require.NotContains(t, environment, mnemonic.CommandVariable+"=")
	require.Contains(t, environment, marker+"=")
}

func TestAFailingCommandSaysWhatWentWrong(t *testing.T) {
	t.Setenv(mnemonic.CommandVariable, "")
	t.Setenv(mnemonic.Variable, "")

	_, err := mnemonic.Read(t.Context(), "echo nothing here >&2; exit 3")
	require.Error(t, err)
	require.Contains(t, err.Error(), "nothing here")
}

func TestValidMnemonicsOf15To24WordsAreAccepted(t *testing.T) {
	t.Setenv(mnemonic.CommandVariable, "")

	// abandon repeated, then the last word that makes the checksum
	// match: 15, 18, 21 and 24 words.
	valid := []string{
		strings.Repeat("abandon ", 14) + "address",
		strings.Repeat("abandon ", 17) + "agent",
		strings.Repeat("abandon ", 20) + "admit",
		strings.Repeat("abandon ", 23) + "art",
	}

	for _, words := range valid {
		t.Setenv(mnemonic.Variable, words)

		got, err := mnemonic.Read(t.Context(), "")
		require.NoError(t, err)
		require.Equal(t, words, got)
	}
}

func TestABadChecksumIsRefused(t *testing.T) {
	t.Setenv(mnemonic.CommandVariable, "")
	t.Setenv(mnemonic.Variable, broken())

	_, err := mnemonic.Read(t.Context(), "")
	require.ErrorIs(t, err, mnemonic.ErrChecksum)
}

func TestACommandThatPrintsNothingGivesAnEmptyMnemonic(t *testing.T) {
	t.Setenv(mnemonic.CommandVariable, "")
	t.Setenv(mnemonic.Variable, "")

	_, err := mnemonic.Read(t.Context(), "true")
	require.ErrorIs(t, err, mnemonic.ErrEmpty)
	require.NotContains(t, err.Error(), "checksum")
}

func TestAWrongWordCountIsRefused(t *testing.T) {
	t.Setenv(mnemonic.CommandVariable, "")
	t.Setenv(mnemonic.Variable, strings.Repeat("abandon ", 3))

	_, err := mnemonic.Read(t.Context(), "")
	require.ErrorIs(t, err, mnemonic.ErrWordCount)
	require.ErrorContains(t, err, "not 3")
	require.NotContains(t, err.Error(), "checksum")
}

func TestAWordNotOnTheListIsNamedByPositionOnly(t *testing.T) {
	const typo = "abuot"

	t.Setenv(mnemonic.CommandVariable, "")
	t.Setenv(mnemonic.Variable, strings.Repeat("abandon ", 11)+typo)

	_, err := mnemonic.Read(t.Context(), "")
	require.ErrorIs(t, err, mnemonic.ErrUnknownWord)
	require.ErrorContains(t, err, "word 12 ")
	require.NotContains(t, err.Error(), typo)
	require.NotContains(t, err.Error(), "checksum")
}

func TestNothingToReadAndNobodyToAsk(t *testing.T) {
	t.Setenv(mnemonic.CommandVariable, "")
	t.Setenv(mnemonic.Variable, "")

	_, err := mnemonic.Read(t.Context(), "")
	require.ErrorIs(t, err, mnemonic.ErrMissing)
}