package cli

import (
	"errors"
	"fmt"
	"log"
	"log/slog"
	"os"
	"strings"

	"git.eeqj.de/sneak/secret/internal/secret"
	"git.eeqj.de/sneak/secret/internal/vault"
	"github.com/awnumar/memguard"
	"github.com/spf13/cobra"
	"github.com/tyler-smith/go-bip39"
)

// errPassphraseMismatch is returned when passphrase confirmation fails
var errPassphraseMismatch = errors.New("passphrases do not match")

// NewInitCmd creates the init command
func NewInitCmd() *cobra.Command {
	return &cobra.Command{
		Use:   "init",
		Short: "Initialize the secrets manager",
		Long: `Create the necessary directory structure for storing ` +
			`secrets and generate encryption keys.`,
		RunE: RunInit,
	}
}

// RunInit is the exported function that handles the init command
func RunInit(cmd *cobra.Command, _ []string) error {
	cli, err := NewCLIInstance()
	if err != nil {
		log.Fatalf("failed to initialize CLI: %v", err)
	}

	destroySecrets := cli.readSecretEnv()
	defer destroySecrets()

	return cli.Init(cmd)
}

// promptMnemonic returns the mnemonic from the environment, cli.Mnemonic,
// or reads it interactively. The returned cleanup function must be deferred
// by the caller.
func (cli *Instance) promptMnemonic() (*memguard.LockedBuffer, func(), error) {
	if cli.Mnemonic != nil {
		secret.Debug("Using mnemonic from environment variable")

		return cli.Mnemonic, func() {}, nil
	}

	secret.Debug("Prompting user for mnemonic phrase")

	// Read mnemonic securely without echo
	mnemonicBuffer, err := secret.ReadPassphrase("Enter your BIP39 mnemonic phrase: ")
	if err != nil {
		secret.Debug("Failed to read mnemonic from stdin", "error", err)

		return nil, nil, fmt.Errorf("failed to read mnemonic: %w", err)
	}

	fmt.Fprintln(os.Stderr) // Add newline after hidden input

	return mnemonicBuffer, mnemonicBuffer.Destroy, nil
}

// Init initializes the secret manager, holding the state directory lock
// while initialize runs
func (cli *Instance) Init(cmd *cobra.Command) error {
	release, err := vault.LockStateDir(cli.fs, cli.stateDir)
	if err != nil {
		return err
	}
	defer release()

	return cli.initialize(cmd)
}

// initialize creates the state directory, the default vault and its first
// unlocker
func (cli *Instance) initialize(cmd *cobra.Command) error {
	secret.Debug("Starting secret manager initialization")

	// Create state directory
	stateDir := cli.GetStateDir()
	secret.DebugWith("Creating state directory", slog.String("path", stateDir))

	err := cli.fs.MkdirAll(stateDir, secret.DirPerms)
	if err != nil {
		secret.Debug("Failed to create state directory", "error", err)

		return fmt.Errorf("failed to create state directory: %w", err)
	}

	if cmd != nil {
		cmd.Printf("Initialized secrets manager at: %s\n", stateDir)
	}

	// Prompt for mnemonic
	mnemonic, cleanupMnemonic, err := cli.promptMnemonic()
	if err != nil {
		return err
	}
	defer cleanupMnemonic()

	mnemonicStr := mnemonic.String()
	if mnemonicStr == "" {
		secret.Debug("Empty mnemonic provided")

		return errMnemonicEmpty
	}

	// Validate the mnemonic using BIP39
	secret.DebugWith("Validating BIP39 mnemonic",
		slog.Int("word_count", len(strings.Fields(mnemonicStr))))

	if !bip39.IsMnemonicValid(mnemonicStr) {
		secret.Debug("Invalid BIP39 mnemonic provided")

		return fmt.Errorf(
			"%w\nRun 'secret generate mnemonic' to create a valid mnemonic",
			errInvalidMnemonicPhrase)
	}

	// Ask for the unlocker passphrase before creating the vault, so that
	// stopping at the prompt leaves no vault without an unlocker behind
	passphraseBuffer, cleanupPassphrase, err := cli.resolvePassphrase()
	if err != nil {
		return err
	}
	defer cleanupPassphrase()

	// Create the default vault with its passphrase unlocker
	secret.Debug("Creating default vault")

	vlt, err := vault.CreateVault(cli.fs, cli.stateDir, "default",
		mnemonic, passphraseBuffer)
	if err != nil {
		secret.Debug("Failed to create default vault", "error", err)

		return fmt.Errorf("failed to create default vault: %w", err)
	}

	ltIdentity, err := vlt.GetOrDeriveLongTermKey()
	if err != nil {
		return fmt.Errorf("failed to get long-term key: %w", err)
	}

	unlocker, err := vlt.GetCurrentUnlocker()
	if err != nil {
		return err
	}

	if cmd != nil {
		cmd.Printf("\nDefault vault created and configured\n")
		cmd.Printf("Long-term public key: %s\n", ltIdentity.Recipient().String())
		cmd.Printf("Unlocker ID: %s\n", unlocker.GetID())
		cmd.Println("\nYour secret manager is ready to use!")
		cmd.Println("Note: When using SB_SECRET_MNEMONIC environment variable,")
		cmd.Println("unlockers are not required for secret operations.")
	}

	return nil
}

// readSecurePassphrase reads a passphrase securely from the terminal without echoing
// This version adds confirmation (read twice) for creating new unlockers
// Returns a LockedBuffer containing the passphrase
func readSecurePassphrase(prompt string) (*memguard.LockedBuffer, error) {
	// Get the first passphrase
	passphraseBuffer1, err := secret.ReadPassphrase(prompt)
	if err != nil {
		return nil, err
	}

	// Read confirmation passphrase
	passphraseBuffer2, err := secret.ReadPassphrase("Confirm passphrase: ")
	if err != nil {
		passphraseBuffer1.Destroy()

		return nil, fmt.Errorf("failed to read passphrase confirmation: %w", err)
	}

	// Compare passphrases
	if passphraseBuffer1.String() != passphraseBuffer2.String() {
		passphraseBuffer1.Destroy()
		passphraseBuffer2.Destroy()

		return nil, errPassphraseMismatch
	}

	// Clean up the second buffer, we'll return the first
	passphraseBuffer2.Destroy()

	// Return the first buffer (caller is responsible for destroying it)
	return passphraseBuffer1, nil
}