package authelia

import (
	"fmt"
	"os"

	"gopkg.in/yaml.v3"

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

// OIDCClient represents a registered OIDC client application
type OIDCClient struct {
	ID           string   `yaml:"client_id" json:"clientId"`
	Name         string   `yaml:"client_name" json:"clientName"`
	Secret       string   `yaml:"client_secret" json:"clientSecret,omitempty"` // pbkdf2 hash in config, cleartext on create response
	RedirectURIs []string `yaml:"redirect_uris" json:"redirectUris"`
	Scopes       []string `yaml:"scopes" json:"scopes"`
	Policy       string   `yaml:"authorization_policy" json:"authorizationPolicy"`
	ConsentMode  string   `yaml:"consent_mode,omitempty" json:"consentMode,omitempty"`
}

// OIDCClientUpdate holds partial updates for an OIDC client
type OIDCClientUpdate struct {
	Name         *string  `json:"clientName,omitempty"`
	RedirectURIs []string `json:"redirectUris,omitempty"`
	Scopes       []string `json:"scopes,omitempty"`
	Policy       *string  `json:"authorizationPolicy,omitempty"`
	ConsentMode  *string  `json:"consentMode,omitempty"`
}

// oidcClientsFile is the top-level structure of the OIDC clients file
type oidcClientsFile struct {
	Clients []OIDCClient `yaml:"clients"`
}

// ListOIDCClients returns all registered OIDC clients (secrets redacted)
func (m *Manager) ListOIDCClients() ([]OIDCClient, error) {
	clients, err := m.readOIDCClients()
	if err != nil {
		return nil, err
	}

	// Redact secrets for listing
	for i := range clients {
		clients[i].Secret = ""
	}
	return clients, nil
}

// ReadOIDCClients returns all clients with secrets (for config generation)
func (m *Manager) ReadOIDCClients() ([]OIDCClient, error) {
	return m.readOIDCClients()
}

// AddOIDCClient adds a new OIDC client. Returns the cleartext secret (shown once).
func (m *Manager) AddOIDCClient(client OIDCClient) (cleartextSecret string, err error) {
	if client.ID == "" {
		return "", fmt.Errorf("client_id is required")
	}
	if client.Name == "" {
		return "", fmt.Errorf("client_name is required")
	}
	if len(client.RedirectURIs) == 0 {
		return "", fmt.Errorf("at least one redirect_uri is required")
	}

	lockPath := m.configPath() + ".lock"
	err = storage.WithLock(lockPath, func() error {
		clients, readErr := m.readOIDCClients()
		if readErr != nil {
			return readErr
		}

		for _, c := range clients {
			if c.ID == client.ID {
				return fmt.Errorf("client %q already exists", client.ID)
			}
		}

		// Generate client secret
		secret, genErr := GenerateSecret(32)
		if genErr != nil {
			return fmt.Errorf("generating client secret: %w", genErr)
		}
		cleartextSecret = secret

		// Hash for storage
		client.Secret = hashClientSecret(secret)

		// Default scopes
		if len(client.Scopes) == 0 {
			client.Scopes = []string{"openid", "profile", "email", "groups"}
		}
		if client.Policy == "" {
			client.Policy = "one_factor"
		}

		return m.writeOIDCClients(append(clients, client))
	})
	return
}

// UpdateOIDCClient applies partial updates to an OIDC client
func (m *Manager) UpdateOIDCClient(clientID string, updates OIDCClientUpdate) error {
	lockPath := m.configPath() + ".lock"
	return storage.WithLock(lockPath, func() error {
		clients, err := m.readOIDCClients()
		if err != nil {
			return err
		}

		found := false
		for i, c := range clients {
			if c.ID == clientID {
				if updates.Name != nil {
					clients[i].Name = *updates.Name
				}
				if updates.RedirectURIs != nil {
					clients[i].RedirectURIs = updates.RedirectURIs
				}
				if updates.Scopes != nil {
					clients[i].Scopes = updates.Scopes
				}
				if updates.Policy != nil {
					clients[i].Policy = *updates.Policy
				}
				if updates.ConsentMode != nil {
					clients[i].ConsentMode = *updates.ConsentMode
				}
				found = true
				break
			}
		}
		if !found {
			return fmt.Errorf("client %q not found", clientID)
		}

		return m.writeOIDCClients(clients)
	})
}

// DeleteOIDCClient removes an OIDC client by ID
func (m *Manager) DeleteOIDCClient(clientID string) error {
	lockPath := m.configPath() + ".lock"
	return storage.WithLock(lockPath, func() error {
		clients, err := m.readOIDCClients()
		if err != nil {
			return err
		}

		var filtered []OIDCClient
		found := false
		for _, c := range clients {
			if c.ID == clientID {
				found = true
				continue
			}
			filtered = append(filtered, c)
		}
		if !found {
			return fmt.Errorf("client %q not found", clientID)
		}

		return m.writeOIDCClients(filtered)
	})
}

// OIDCClientCount returns the number of registered OIDC clients
func (m *Manager) OIDCClientCount() int {
	clients, err := m.readOIDCClients()
	if err != nil {
		return 0
	}
	return len(clients)
}

// readOIDCClients reads OIDC clients from the dedicated clients file
func (m *Manager) readOIDCClients() ([]OIDCClient, error) {
	data, err := os.ReadFile(m.oidcClientsPath())
	if err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, fmt.Errorf("reading oidc clients: %w", err)
	}

	var f oidcClientsFile
	if err := yaml.Unmarshal(data, &f); err != nil {
		return nil, fmt.Errorf("parsing oidc clients: %w", err)
	}

	return f.Clients, nil
}

// writeOIDCClients writes the OIDC clients to the dedicated clients file
func (m *Manager) writeOIDCClients(clients []OIDCClient) error {
	f := oidcClientsFile{Clients: clients}
	data, err := yaml.Marshal(f)
	if err != nil {
		return fmt.Errorf("marshaling oidc clients: %w", err)
	}

	tmpPath := m.oidcClientsPath() + ".tmp"
	if err := os.WriteFile(tmpPath, data, 0600); err != nil {
		return fmt.Errorf("writing temp oidc clients: %w", err)
	}
	if err := os.Rename(tmpPath, m.oidcClientsPath()); err != nil {
		os.Remove(tmpPath)
		return fmt.Errorf("installing oidc clients: %w", err)
	}
	return nil
}

// hashClientSecret wraps the secret with $plaintext$ prefix.
// Authelia accepts this format and handles hashing internally.
func hashClientSecret(secret string) string {
	return "$plaintext$" + secret
}