<?php
/**
 * LDAP Authentication Class
 * Handles LDAP directory authentication and user information retrieval
 */

class LDAPAuth {
    private $connection;
    private $config;
    
    public function __construct() {
        $this->config = [
            'host' => LDAP_HOST,
            'port' => LDAP_PORT,
            'base_dn' => LDAP_BASE_DN,
            'user_filter' => LDAP_USER_FILTER,
            'bind_dn' => LDAP_BIND_DN,
            'bind_password' => LDAP_BIND_PASSWORD,
            'email_attribute' => LDAP_EMAIL_ATTRIBUTE,
            'name_attribute' => LDAP_NAME_ATTRIBUTE
        ];
    }
    
    public function authenticate($username, $password) {
        try {
            // Connect to LDAP server
            $this->connect();
            
            // First bind with service account if configured
            if (!empty($this->config['bind_dn'])) {
                if (!ldap_bind($this->connection, $this->config['bind_dn'], $this->config['bind_password'])) {
                    throw new Exception('LDAP bind failed with service account');
                }
            }
            
            // Search for user
            $filter = str_replace('{username}', ldap_escape($username, '', LDAP_ESCAPE_FILTER), $this->config['user_filter']);
            $search = ldap_search($this->connection, $this->config['base_dn'], $filter, [$this->config['email_attribute'], $this->config['name_attribute'], 'dn']);
            
            if (!$search) {
                throw new Exception('LDAP search failed');
            }
            
            $entries = ldap_get_entries($this->connection, $search);
            
            if ($entries['count'] === 0) {
                return false;
            }
            
            $user_dn = $entries[0]['dn'];
            
            // Try to bind with user credentials
            if (@ldap_bind($this->connection, $user_dn, $password)) {
                return true;
            }
            
            return false;
            
        } catch (Exception $e) {
            error_log('LDAP Authentication Error: ' . $e->getMessage());
            return false;
        } finally {
            $this->disconnect();
        }
    }
    
    public function getUserInfo($username) {
        try {
            $this->connect();
            
            // Bind with service account if configured
            if (!empty($this->config['bind_dn'])) {
                if (!ldap_bind($this->connection, $this->config['bind_dn'], $this->config['bind_password'])) {
                    throw new Exception('LDAP bind failed with service account');
                }
            }
            
            // Search for user
            $filter = str_replace('{username}', ldap_escape($username, '', LDAP_ESCAPE_FILTER), $this->config['user_filter']);
            $search = ldap_search($this->connection, $this->config['base_dn'], $filter, [
                $this->config['email_attribute'], 
                $this->config['name_attribute'], 
                'dn',
                'cn',
                'givenName',
                'sn',
                'mail',
                'uid'
            ]);
            
            if (!$search) {
                throw new Exception('LDAP search failed');
            }
            
            $entries = ldap_get_entries($this->connection, $search);
            
            if ($entries['count'] === 0) {
                return null;
            }
            
            $user_entry = $entries[0];
            
            $userInfo = [
                'ldap_dn' => $user_entry['dn'],
                'username' => $username,
                'email' => $this->getLdapAttribute($user_entry, $this->config['email_attribute']),
                'name' => $this->getLdapAttribute($user_entry, $this->config['name_attribute']),
                'first_name' => $this->getLdapAttribute($user_entry, 'givenName'),
                'last_name' => $this->getLdapAttribute($user_entry, 'sn'),
                'full_name' => $this->getLdapAttribute($user_entry, 'cn'),
                'uid' => $this->getLdapAttribute($user_entry, 'uid')
            ];
            
            return $userInfo;
            
        } catch (Exception $e) {
            error_log('LDAP User Info Error: ' . $e->getMessage());
            return null;
        } finally {
            $this->disconnect();
        }
    }
    
    public function testConnection() {
        try {
            $this->connect();
            
            // Test bind
            if (!empty($this->config['bind_dn'])) {
                $bind_result = ldap_bind($this->connection, $this->config['bind_dn'], $this->config['bind_password']);
            } else {
                $bind_result = ldap_bind($this->connection);
            }
            
            if (!$bind_result) {
                throw new Exception('LDAP bind failed');
            }
            
            // Test search
            $search = ldap_search($this->connection, $this->config['base_dn'], '(objectClass=*)', ['dn']);
            if (!$search) {
                throw new Exception('LDAP search failed');
            }
            
            return true;
            
        } catch (Exception $e) {
            error_log('LDAP Connection Test Error: ' . $e->getMessage());
            return false;
        } finally {
            $this->disconnect();
        }
    }
    
    private function connect() {
        $connection_string = $this->config['host'] . ':' . $this->config['port'];
        
        // Suppress LDAP warnings for cleaner error handling
        $this->connection = @ldap_connect($connection_string);
        
        if (!$this->connection) {
            error_log('LDAP Connection Error: Failed to connect to LDAP server');
            throw new Exception('Failed to connect to LDAP server');
        }
        
        // Set LDAP options
        ldap_set_option($this->connection, LDAP_OPT_PROTOCOL_VERSION, 3);
        ldap_set_option($this->connection, LDAP_OPT_REFERRALS, 0);
        
        // Enable TLS if using port 636
        if ($this->config['port'] == 636) {
            if (!ldap_start_tls($this->connection)) {
                throw new Exception('Failed to start TLS');
            }
        }
    }
    
    private function disconnect() {
        if ($this->connection) {
            ldap_close($this->connection);
            $this->connection = null;
        }
    }
    
    private function getLdapAttribute($entry, $attribute) {
        if (isset($entry[$attribute])) {
            if ($entry[$attribute]['count'] > 1) {
                return $entry[$attribute][0]; // Return first value for multi-valued attributes
            }
            return $entry[$attribute][0];
        }
        return null;
    }
    
    public function searchUsers($query = '', $limit = 50) {
        try {
            $this->connect();
            
            // Bind with service account if configured
            if (!empty($this->config['bind_dn'])) {
                if (!ldap_bind($this->connection, $this->config['bind_dn'], $this->config['bind_password'])) {
                    throw new Exception('LDAP bind failed with service account');
                }
            }
            
            // Build search filter
            if ($query) {
                $escaped_query = ldap_escape($query, '', LDAP_ESCAPE_FILTER);
                $filter = "(&(|(uid=*$escaped_query*)(cn=*$escaped_query*)(mail=*$escaped_query*)(givenName=*$escaped_query*)(sn=*$escaped_query*))(!(objectClass=computer)))";
            } else {
                $filter = "(&(objectClass=person)(!(objectClass=computer)))";
            }
            
            $search = ldap_search($this->connection, $this->config['base_dn'], $filter, [
                'uid',
                'cn',
                'givenName',
                'sn',
                'mail',
                'dn'
            ]);
            
            if (!$search) {
                throw new Exception('LDAP search failed');
            }
            
            ldap_control_paged_result($this->connection, $limit);
            $entries = ldap_get_entries($this->connection, $search);
            
            $users = [];
            for ($i = 0; $i < $entries['count']; $i++) {
                $user_entry = $entries[$i];
                $users[] = [
                    'username' => $this->getLdapAttribute($user_entry, 'uid'),
                    'name' => $this->getLdapAttribute($user_entry, 'cn'),
                    'first_name' => $this->getLdapAttribute($user_entry, 'givenName'),
                    'last_name' => $this->getLdapAttribute($user_entry, 'sn'),
                    'email' => $this->getLdapAttribute($user_entry, 'mail'),
                    'ldap_dn' => $user_entry['dn']
                ];
            }
            
            return $users;
            
        } catch (Exception $e) {
            error_log('LDAP User Search Error: ' . $e->getMessage());
            return [];
        } finally {
            $this->disconnect();
        }
    }
}