package secrets

import (
	"bytes"
	"crypto/rand"
	"fmt"
	"math/big"
	"os/exec"
	"path/filepath"
	"strings"

	"github.com/wild-cloud/wild-central/internal/storage"
)

// YQ provides a wrapper around the yq command-line tool
type YQ struct {
	yqPath string
}

// NewYQ creates a new YQ wrapper
func NewYQ() *YQ {
	path, err := exec.LookPath("yq")
	if err != nil {
		path = "yq"
	}
	return &YQ{yqPath: path}
}

// Get retrieves a value from a YAML file using a yq expression
func (y *YQ) Get(filePath, expression string) (string, error) {
	cmd := exec.Command(y.yqPath, expression, filePath)
	var stdout, stderr bytes.Buffer
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr
	if err := cmd.Run(); err != nil {
		return "", fmt.Errorf("yq get failed: %w, stderr: %s", err, stderr.String())
	}
	return strings.TrimSpace(stdout.String()), nil
}

// Set sets a value in a YAML file using a yq expression
func (y *YQ) Set(filePath, expression, value string) error {
	if !strings.HasPrefix(expression, ".") {
		expression = "." + expression
	}
	quotedValue := fmt.Sprintf(`"%s"`, strings.ReplaceAll(value, `"`, `\"`))
	setExpr := fmt.Sprintf("%s = %s", expression, quotedValue)
	cmd := exec.Command(y.yqPath, "-i", setExpr, filePath)
	var stderr bytes.Buffer
	cmd.Stderr = &stderr
	if err := cmd.Run(); err != nil {
		return fmt.Errorf("yq set failed: %w, stderr: %s", err, stderr.String())
	}
	return nil
}

// Delete removes a key from a YAML file
func (y *YQ) Delete(filePath, expression string) error {
	delExpr := fmt.Sprintf("del(%s)", expression)
	cmd := exec.Command(y.yqPath, "-i", delExpr, filePath)
	var stderr bytes.Buffer
	cmd.Stderr = &stderr
	if err := cmd.Run(); err != nil {
		return fmt.Errorf("yq delete failed: %w, stderr: %s", err, stderr.String())
	}
	return nil
}

// Validate checks if a YAML file is valid
func (y *YQ) Validate(filePath string) error {
	cmd := exec.Command(y.yqPath, "eval", ".", filePath)
	var stderr bytes.Buffer
	cmd.Stderr = &stderr
	if err := cmd.Run(); err != nil {
		return fmt.Errorf("yaml validation failed: %w, stderr: %s", err, stderr.String())
	}
	return nil
}

const (
	// DefaultSecretLength is 32 characters
	DefaultSecretLength = 32
	// Alphanumeric characters for secret generation
	alphanumeric = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
)

// Manager handles secret generation and storage
type Manager struct {
	yq *YQ
}

// NewManager creates a new secrets manager
func NewManager() *Manager {
	return &Manager{
		yq: NewYQ(),
	}
}

// GenerateSecret generates a cryptographically secure random alphanumeric string
func GenerateSecret(length int) (string, error) {
	if length <= 0 {
		length = DefaultSecretLength
	}

	result := make([]byte, length)
	for i := range result {
		num, err := rand.Int(rand.Reader, big.NewInt(int64(len(alphanumeric))))
		if err != nil {
			return "", fmt.Errorf("generating random number: %w", err)
		}
		result[i] = alphanumeric[num.Int64()]
	}

	return string(result), nil
}

// EnsureSecretsFile ensures a secrets file exists with proper structure and permissions
func (m *Manager) EnsureSecretsFile(dataDir, instanceName string) error {
	secretsPath := filepath.Join(dataDir, "instances", instanceName, "config", "secrets.yaml")

	// Check if secrets file already exists
	if storage.FileExists(secretsPath) {
		// Ensure proper permissions
		if err := storage.EnsureFilePermissions(secretsPath, 0600); err != nil {
			return err
		}
		return nil
	}

	// Create minimal secrets structure
	initialSecrets := `# Wild Cloud Instance Secrets
# WARNING: This file contains sensitive data. Keep secure!
cluster:
  talosSecrets: ""
  kubeconfig: ""
cloudflare:
  token: ""
`

	// Ensure config directory exists
	if err := storage.EnsureDir(filepath.Join(dataDir, "instances", instanceName, "config"), 0755); err != nil {
		return err
	}

	// Write secrets file with restrictive permissions (0600)
	if err := storage.WriteFile(secretsPath, []byte(initialSecrets), 0600); err != nil {
		return err
	}

	return nil
}

// GetSecret retrieves a secret value from a secrets file
func (m *Manager) GetSecret(secretsPath, key string) (string, error) {
	if !storage.FileExists(secretsPath) {
		return "", fmt.Errorf("secrets file not found: %s", secretsPath)
	}

	value, err := m.yq.Get(secretsPath, fmt.Sprintf(".%s", key))
	if err != nil {
		return "", fmt.Errorf("getting secret %s: %w", key, err)
	}

	// yq returns "null" for non-existent keys
	if value == "" || value == "null" {
		return "", fmt.Errorf("secret not found: %s", key)
	}

	return value, nil
}

// SetSecret sets a secret value in a secrets file
func (m *Manager) SetSecret(secretsPath, key, value string) error {
	if !storage.FileExists(secretsPath) {
		return fmt.Errorf("secrets file not found: %s", secretsPath)
	}

	// Acquire lock before modifying
	lockPath := secretsPath + ".lock"
	return storage.WithLock(lockPath, func() error {
		// Don't wrap value in quotes - yq handles YAML quoting automatically
		if err := m.yq.Set(secretsPath, fmt.Sprintf(".%s", key), value); err != nil {
			return err
		}
		// Ensure permissions remain secure after modification
		return storage.EnsureFilePermissions(secretsPath, 0600)
	})
}

// EnsureSecret generates and sets a secret only if it doesn't exist (idempotent)
func (m *Manager) EnsureSecret(secretsPath, key string, length int) (string, error) {
	if !storage.FileExists(secretsPath) {
		return "", fmt.Errorf("secrets file not found: %s", secretsPath)
	}

	// Check if secret already exists
	existingSecret, err := m.GetSecret(secretsPath, key)
	if err == nil && existingSecret != "" && existingSecret != "null" {
		// Secret already exists, return it
		return existingSecret, nil
	}

	// Generate new secret
	secret, err := GenerateSecret(length)
	if err != nil {
		return "", err
	}

	// Set the secret
	if err := m.SetSecret(secretsPath, key, secret); err != nil {
		return "", err
	}

	return secret, nil
}

// GenerateAndStoreSecret is a convenience function that generates a secret and stores it
func (m *Manager) GenerateAndStoreSecret(secretsPath, key string) (string, error) {
	return m.EnsureSecret(secretsPath, key, DefaultSecretLength)
}

// DeleteSecret removes a secret from a secrets file
func (m *Manager) DeleteSecret(secretsPath, key string) error {
	if !storage.FileExists(secretsPath) {
		return fmt.Errorf("secrets file not found: %s", secretsPath)
	}

	// Acquire lock before modifying
	lockPath := secretsPath + ".lock"
	return storage.WithLock(lockPath, func() error {
		if err := m.yq.Delete(secretsPath, fmt.Sprintf(".%s", key)); err != nil {
			return err
		}
		// Ensure permissions remain secure after modification
		return storage.EnsureFilePermissions(secretsPath, 0600)
	})
}