package cli_test

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

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"

	"sneak.berlin/go/x/internal/cli"
	"sneak.berlin/go/x/internal/pwgen"
	"sneak.berlin/go/x/pkg/bip39wordlist"
	"sneak.berlin/go/x/pkg/cbk"
)

const (
	testVersion = "v1.2.3-test"

	// vectorRepeats is how many times "abandon" appears in the standard
	// BIP39 test vector for all-zero 128-bit entropy, which ends with
	// "about".
	vectorRepeats = bip39wordlist.MinWordCount - 1
)

// vectorMnemonic returns the standard BIP39 test vector for all-zero
// 128-bit entropy.
func vectorMnemonic() string {
	return strings.Repeat("abandon ", vectorRepeats) + "about"
}

func TestVersionCommand(t *testing.T) {
	t.Parallel()

	output, err := execute(t, "", "version")
	require.NoError(t, err)
	assert.Equal(t, testVersion+"\n", output)
}

func TestVersionFlag(t *testing.T) {
	t.Parallel()

	output, err := execute(t, "", "--version")
	require.NoError(t, err)
	assert.Contains(t, output, testVersion)
}

func TestInfoCommand(t *testing.T) {
	t.Parallel()

	output, err := execute(t, "", "info")
	require.NoError(t, err)
	assert.Contains(t, output, "version: "+testVersion+"\n")
	assert.Contains(t, output, "go: go")
	assert.Contains(t, output, "module: sneak.berlin/go/x\n")
	assert.Contains(t, output, "config: (none)\n")
}

func TestConfigFileDiscoveredInConfigDir(t *testing.T) {
	t.Parallel()

	configDir := t.TempDir()
	path := filepath.Join(configDir, ".sneak.yaml")
	require.NoError(t, os.WriteFile(path, []byte("example: 1\n"), 0o600))

	params := cli.Params{Version: testVersion, ConfigDir: configDir}

	output, err := executeWithParams(t, params, "", "info")
	require.NoError(t, err)
	assert.Contains(t, output, "Using config file: "+path+"\n")
	assert.Contains(t, output, "config: "+path+"\n")
}

func TestConfigFlagLoadsNamedFile(t *testing.T) {
	t.Parallel()

	path := filepath.Join(t.TempDir(), "elsewhere.yaml")
	require.NoError(t, os.WriteFile(path, []byte("example: 1\n"), 0o600))

	output, err := execute(t, "", "--config", path, "info")
	require.NoError(t, err)
	assert.Contains(t, output, "Using config file: "+path+"\n")
	assert.Contains(t, output, "config: "+path+"\n")
}

func TestConfigFlagRejectsMissingFile(t *testing.T) {
	t.Parallel()

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

	_, err := execute(t, "", "--config", path, "version")
	require.Error(t, err)
}

func TestConfigRejectsMalformedFile(t *testing.T) {
	t.Parallel()

	configDir := t.TempDir()
	path := filepath.Join(configDir, ".sneak.yaml")
	require.NoError(t, os.WriteFile(path, []byte("not: [valid\n"), 0o600))

	params := cli.Params{Version: testVersion, ConfigDir: configDir}

	_, err := executeWithParams(t, params, "", "version")
	require.Error(t, err)
}

func TestGenerateRandomSeededIsDeterministic(t *testing.T) {
	t.Parallel()

	first, err := execute(t, "", "generate", "random", "--count", "4096", "seed")
	require.NoError(t, err)
	assert.Len(t, first, 4096)

	second, err := execute(t, "", "generate", "random", "--count", "4096", "seed")
	require.NoError(t, err)
	assert.Equal(t, first, second)

	other, err := execute(t, "", "gen", "random", "-c", "4096", "other seed")
	require.NoError(t, err)
	assert.NotEqual(t, first, other)
}

func TestGenerateRandomUnseeded(t *testing.T) {
	t.Parallel()

	first, err := execute(t, "", "generate", "random", "--count", "1024")
	require.NoError(t, err)
	assert.Len(t, first, 1024)

	second, err := execute(t, "", "generate", "random", "--count", "1024")
	require.NoError(t, err)
	assert.NotEqual(t, first, second)
}

func TestGenerateRandomRejectsExtraArguments(t *testing.T) {
	t.Parallel()

	_, err := execute(t, "", "generate", "random", "one", "two")
	require.Error(t, err)
}

func TestGenerateMnemonic(t *testing.T) {
	t.Parallel()

	output, err := execute(t, "", "generate", "mnemonic")
	require.NoError(t, err)

	mnemonic := strings.TrimSuffix(output, "\n")
	require.NoError(t, bip39wordlist.ValidateWordlist(mnemonic))
	assert.Len(t, strings.Fields(mnemonic), bip39wordlist.MaxWordCount)

	output, err = execute(t, "", "generate", "mnemonic", "--words", "12")
	require.NoError(t, err)
	assert.Len(t, strings.Fields(output), bip39wordlist.MinWordCount)

	_, err = execute(t, "", "generate", "mnemonic", "--words", "13")
	require.ErrorIs(t, err, bip39wordlist.ErrInvalidWordCount)
}

func TestGeneratePassword(t *testing.T) {
	t.Parallel()

	_, err := pwgen.New(pwgen.Params{Words: nil, MinWordLength: 0, MaxWordLength: 0})
	if errors.Is(err, pwgen.ErrNoUsableWords) {
		t.Skip("this system has no word list")
	}

	require.NoError(t, err)

	output, err := execute(t, "", "generate", "password")
	require.NoError(t, err)

	password := strings.TrimSuffix(output, "\n")
	assert.NotContains(t, password, "\n")
	assert.GreaterOrEqual(t, len(password), 3*(pwgen.DefaultMinWordLength+1)+2)
	assert.True(t, strings.ContainsAny(password, "0123456789"), password)
	assert.True(t, strings.ContainsAny(password, pwgen.Delimiters), password)
}

func TestCBKDerive(t *testing.T) {
	t.Parallel()

	expected, err := cbk.FromMnemonic(vectorMnemonic())
	require.NoError(t, err)

	stdin := "  " + strings.ToUpper(vectorMnemonic()) + "\n"

	output, err := execute(t, stdin, "cbk", "derive")
	require.NoError(t, err)
	assert.Equal(t,
		"public: "+expected.PublicKeyHex()+"\n"+
			"private: "+expected.PrivateKeyHex()+"\n",
		output,
	)

	output, err = execute(t, vectorMnemonic(), "cbk", "derive", "--public")
	require.NoError(t, err)
	assert.Equal(t, expected.PublicKeyHex()+"\n", output)
}

func TestCBKDeriveRejectsInvalidMnemonic(t *testing.T) {
	t.Parallel()

	_, err := execute(t, "not a mnemonic\n", "cbk", "derive")
	require.ErrorIs(t, err, bip39wordlist.ErrInvalidWordCount)
}

// execute runs sutil with the given stdin and arguments, looking for config
// in an empty temporary directory, and returns everything it wrote to
// stdout and stderr.
func execute(t *testing.T, stdin string, args ...string) (string, error) {
	t.Helper()

	params := cli.Params{Version: testVersion, ConfigDir: t.TempDir()}

	return executeWithParams(t, params, stdin, args...)
}

// executeWithParams is execute with explicit Params.
func executeWithParams(
	t *testing.T, params cli.Params, stdin string, args ...string,
) (string, error) {
	t.Helper()

	root := cli.New(params)

	var output bytes.Buffer

	root.SetOut(&output)
	root.SetErr(&output)
	root.SetIn(strings.NewReader(stdin))
	root.SetArgs(args)

	err := root.Execute()

	return output.String(), err
}