<?php

namespace KTXC\Logger;

use Psr\Log\LoggerInterface;
use Psr\Log\LogLevel;

/**
 * PSR-3 logger that writes via PHP's built-in syslog() facility.
 *
 * Each message is prefixed with "[channel] " so entries can be filtered easily
 * in /var/log/syslog (or equivalent) or via journalctl -t {ident}.
 */
class SyslogLogger implements LoggerInterface
{
    /** Maps PSR-3 levels to PHP syslog priority constants */
    private const PRIORITY = [
        LogLevel::EMERGENCY => LOG_EMERG,
        LogLevel::ALERT     => LOG_ALERT,
        LogLevel::CRITICAL  => LOG_CRIT,
        LogLevel::ERROR     => LOG_ERR,
        LogLevel::WARNING   => LOG_WARNING,
        LogLevel::NOTICE    => LOG_NOTICE,
        LogLevel::INFO      => LOG_INFO,
        LogLevel::DEBUG     => LOG_DEBUG,
    ];

    public function __construct(
        private readonly string $ident    = 'ktrix',
        private readonly int    $facility = LOG_USER,
        private readonly string $channel  = 'app',
    ) {}

    public function emergency($message, array $context = []): void { $this->log(LogLevel::EMERGENCY, $message, $context); }
    public function alert($message, array $context = []): void      { $this->log(LogLevel::ALERT,     $message, $context); }
    public function critical($message, array $context = []): void   { $this->log(LogLevel::CRITICAL,  $message, $context); }
    public function error($message, array $context = []): void      { $this->log(LogLevel::ERROR,     $message, $context); }
    public function warning($message, array $context = []): void    { $this->log(LogLevel::WARNING,   $message, $context); }
    public function notice($message, array $context = []): void     { $this->log(LogLevel::NOTICE,    $message, $context); }
    public function info($message, array $context = []): void       { $this->log(LogLevel::INFO,      $message, $context); }
    public function debug($message, array $context = []): void      { $this->log(LogLevel::DEBUG,     $message, $context); }

    public function log($level, $message, array $context = []): void
    {
        // Extract tenant id injected by TenantAwareLogger; default to 'system'.
        $tenantId = isset($context['__tenant']) && is_string($context['__tenant'])
            ? $context['__tenant']
            : 'system';
        unset($context['__tenant']);

        $level    = strtolower((string) $level);
        $priority = self::PRIORITY[$level] ?? LOG_DEBUG;

        $interpolated = $this->interpolate((string) $message, $context);
        $contextStr   = empty($context) ? '' : ' ' . $this->encodeContext($context);

        $entry = sprintf('[%s] [%s] %s%s', $this->channel, $tenantId, $interpolated, $contextStr);

        openlog($this->ident, LOG_NDELAY | LOG_PID, $this->facility);
        syslog($priority, $entry);
        closelog();
    }

    private function interpolate(string $message, array $context): string
    {
        if (!str_contains($message, '{')) {
            return $message;
        }
        $replace = [];
        foreach ($context as $key => $val) {
            if (!is_array($val) && !is_object($val)) {
                $replace['{' . $key . '}'] = (string) $val;
            }
        }
        return strtr($message, $replace);
    }

    private function encodeContext(array $context): string
    {
        $clean = [];
        foreach ($context as $k => $v) {
            if ($v instanceof \Throwable) {
                $clean[$k] = ['type' => get_class($v), 'message' => $v->getMessage()];
            } elseif (is_resource($v)) {
                $clean[$k] = 'resource(' . get_resource_type($v) . ')';
            } elseif (is_object($v)) {
                $clean[$k] = method_exists($v, '__toString') ? (string) $v : ['object' => get_class($v)];
            } else {
                $clean[$k] = $v;
            }
        }
        return json_encode($clean, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE) ?: '{}';
    }
}