package ldap

import (
	"context"
	"fmt"
	"strings"

	"github.com/seaweedfs/seaweedfs/weed/iam/providers"
)

// LDAPProvider implements LDAP authentication
type LDAPProvider struct {
	name        string
	config      *LDAPConfig
	initialized bool
	connPool    interface{} // Will be proper LDAP connection pool
}

// LDAPConfig holds LDAP provider configuration
type LDAPConfig struct {
	// Server is the LDAP server URL (e.g., ldap://localhost:389)
	Server string `json:"server"`

	// BaseDN is the base distinguished name for searches
	BaseDN string `json:"baseDn"`

	// BindDN is the distinguished name for binding (authentication)
	BindDN string `json:"bindDn,omitempty"`

	// BindPass is the password for binding
	BindPass string `json:"bindPass,omitempty"`

	// UserFilter is the LDAP filter for finding users (e.g., "(sAMAccountName=%s)")
	UserFilter string `json:"userFilter"`

	// GroupFilter is the LDAP filter for finding groups (e.g., "(member=%s)")
	GroupFilter string `json:"groupFilter,omitempty"`

	// Attributes maps SeaweedFS identity fields to LDAP attributes
	Attributes map[string]string `json:"attributes,omitempty"`

	// RoleMapping defines how to map LDAP groups to roles
	RoleMapping *providers.RoleMapping `json:"roleMapping,omitempty"`

	// TLS configuration
	UseTLS        bool   `json:"useTls,omitempty"`
	TLSCert       string `json:"tlsCert,omitempty"`
	TLSKey        string `json:"tlsKey,omitempty"`
	TLSSkipVerify bool   `json:"tlsSkipVerify,omitempty"`

	// Connection pool settings
	MaxConnections int `json:"maxConnections,omitempty"`
	ConnTimeout    int `json:"connTimeout,omitempty"` // seconds
}

// NewLDAPProvider creates a new LDAP provider
func NewLDAPProvider(name string) *LDAPProvider {
	return &LDAPProvider{
		name: name,
	}
}

// Name returns the provider name
func (p *LDAPProvider) Name() string {
	return p.name
}

// Initialize initializes the LDAP provider with configuration
func (p *LDAPProvider) Initialize(config interface{}) error {
	if config == nil {
		return fmt.Errorf("config cannot be nil")
	}

	ldapConfig, ok := config.(*LDAPConfig)
	if !ok {
		return fmt.Errorf("invalid config type for LDAP provider")
	}

	if err := p.validateConfig(ldapConfig); err != nil {
		return fmt.Errorf("invalid LDAP configuration: %w", err)
	}

	p.config = ldapConfig
	p.initialized = true

	// For testing, skip actual LDAP connection pool initialization
	return nil
}

// validateConfig validates the LDAP configuration
func (p *LDAPProvider) validateConfig(config *LDAPConfig) error {
	if config.Server == "" {
		return fmt.Errorf("server is required")
	}

	if config.BaseDN == "" {
		return fmt.Errorf("base DN is required")
	}

	// Basic URL validation
	if !strings.HasPrefix(config.Server, "ldap://") && !strings.HasPrefix(config.Server, "ldaps://") {
		return fmt.Errorf("invalid server URL format")
	}

	// Set default user filter if not provided
	if config.UserFilter == "" {
		config.UserFilter = "(uid=%s)" // Default LDAP user filter
	}

	// Set default attributes if not provided
	if config.Attributes == nil {
		config.Attributes = map[string]string{
			"email":       "mail",
			"displayName": "cn",
			"groups":      "memberOf",
		}
	}

	return nil
}

// Authenticate authenticates a user with LDAP
func (p *LDAPProvider) Authenticate(ctx context.Context, credentials string) (*providers.ExternalIdentity, error) {
	if !p.initialized {
		return nil, fmt.Errorf("provider not initialized")
	}

	if credentials == "" {
		return nil, fmt.Errorf("credentials cannot be empty")
	}

	// Parse credentials (username:password format)
	parts := strings.SplitN(credentials, ":", 2)
	if len(parts) != 2 {
		return nil, fmt.Errorf("invalid credentials format (expected username:password)")
	}

	username, password := parts[0], parts[1]

	// TODO: Implement actual LDAP authentication
	// 1. Connect to LDAP server using bind credentials
	// 2. Search for user using configured user filter
	// 3. Attempt to bind with user credentials
	// 4. Retrieve user attributes and group memberships
	// 5. Map to ExternalIdentity structure

	_ = username // Avoid unused variable warning
	_ = password // Avoid unused variable warning

	return nil, fmt.Errorf("LDAP authentication not implemented yet - requires LDAP client integration")
}

// GetUserInfo retrieves user information from LDAP
func (p *LDAPProvider) GetUserInfo(ctx context.Context, userID string) (*providers.ExternalIdentity, error) {
	if !p.initialized {
		return nil, fmt.Errorf("provider not initialized")
	}

	if userID == "" {
		return nil, fmt.Errorf("user ID cannot be empty")
	}

	// TODO: Implement LDAP user information retrieval
	// 1. Connect to LDAP server
	// 2. Search for user by userID using configured user filter
	// 3. Retrieve configured attributes (email, displayName, etc.)
	// 4. Retrieve group memberships using group filter
	// 5. Map to ExternalIdentity structure

	return nil, fmt.Errorf("LDAP user info retrieval not implemented yet")
}

// ValidateToken validates credentials (for LDAP, this is username/password)
func (p *LDAPProvider) ValidateToken(ctx context.Context, token string) (*providers.TokenClaims, error) {
	if !p.initialized {
		return nil, fmt.Errorf("provider not initialized")
	}

	if token == "" {
		return nil, fmt.Errorf("token cannot be empty")
	}

	// Parse credentials (username:password format)
	parts := strings.SplitN(token, ":", 2)
	if len(parts) != 2 {
		return nil, fmt.Errorf("invalid token format (expected username:password)")
	}

	username, password := parts[0], parts[1]

	// TODO: Implement LDAP credential validation
	// 1. Connect to LDAP server
	// 2. Authenticate with service account if configured
	// 3. Search for user using configured user filter
	// 4. Attempt to bind with user credentials to validate password
	// 5. Extract user claims (DN, attributes, group memberships)
	// 6. Return TokenClaims with LDAP-specific information

	_ = username // Avoid unused variable warning
	_ = password // Avoid unused variable warning

	return nil, fmt.Errorf("LDAP credential validation not implemented yet")
}

// mapLDAPAttributes maps LDAP attributes to ExternalIdentity
func (p *LDAPProvider) mapLDAPAttributes(userID string, attrs map[string][]string) *providers.ExternalIdentity {
	identity := &providers.ExternalIdentity{
		UserID:     userID,
		Provider:   p.name,
		Attributes: make(map[string]string),
	}

	// Map configured attributes
	for identityField, ldapAttr := range p.config.Attributes {
		if values, exists := attrs[ldapAttr]; exists && len(values) > 0 {
			switch identityField {
			case "email":
				identity.Email = values[0]
			case "displayName":
				identity.DisplayName = values[0]
			case "groups":
				identity.Groups = values
			default:
				// Store as custom attribute
				identity.Attributes[identityField] = values[0]
			}
		}
	}

	return identity
}

// mapUserToRole maps user groups to roles based on role mapping rules
func (p *LDAPProvider) mapUserToRole(identity *providers.ExternalIdentity) string {
	if p.config.RoleMapping == nil {
		return ""
	}

	// Create token claims from identity for rule matching
	claims := &providers.TokenClaims{
		Subject: identity.UserID,
		Claims: map[string]interface{}{
			"groups": identity.Groups,
			"email":  identity.Email,
		},
	}

	// Check mapping rules
	for _, rule := range p.config.RoleMapping.Rules {
		if rule.Matches(claims) {
			return rule.Role
		}
	}

	// Return default role if no rules match
	return p.config.RoleMapping.DefaultRole
}

// Connection management methods (stubs for now)
func (p *LDAPProvider) getConnectionPool() interface{} {
	return p.connPool
}

func (p *LDAPProvider) getConnection() (interface{}, error) {
	// TODO: Get connection from pool
	return nil, fmt.Errorf("not implemented")
}

func (p *LDAPProvider) releaseConnection(conn interface{}) {
	// TODO: Return connection to pool
}