<?php

namespace KTXC\Logger;

use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;

/**
 * Creates a PSR-3 LoggerInterface instance from the application config.
 *
 * Reads the 'log' key from the system config array and builds:
 *   1. A driver-specific inner logger (file, systemd, syslog, null).
 *   2. A LevelFilterLogger decorator that discards messages below the
 *      configured minimum level.
 *
 * Per-tenant routing (TenantAwareLogger) is applied separately inside the
 * DI container definition in Kernel::configureContainer(), because that
 * requires access to the SessionTenant singleton which lives in the container.
 *
 * Supported config keys inside $config['log']:
 *
 *   driver      string  'file' | 'systemd' | 'syslog' | 'null'   default: 'file'
 *   level       string  PSR-3 level string (minimum to log)        default: 'debug'
 *   per_tenant  bool    Route to per-tenant files (DI-level only)  default: false
 *
 *   -- file driver --
 *   path        ?string Absolute log directory, null = {root}/var/log
 *   channel     string  File basename without extension             default: 'app'
 *
 *   -- systemd driver --
 *   channel     string  Channel tag embedded in each line          default: 'app'
 *
 *   -- syslog driver --
 *   ident       string  openlog() identity tag                     default: 'ktrix'
 *   facility    int     openlog() facility constant                 default: LOG_USER
 *   channel     string  Prefix embedded in each syslog message     default: 'app'
 */
class LoggerFactory
{
    /**
     * Build and return a configured, level-filtered PSR-3 logger.
     *
     * @param array  $config     The full system config array (reads $config['log']).
     * @param string $projectDir Absolute project root path (used for default file path).
     */
    public static function create(array $config, string $projectDir): LoggerInterface
    {
        $logConfig = $config['log'] ?? [];

        $driver  = $logConfig['driver']  ?? 'file';
        $level   = $logConfig['level']   ?? 'debug';
        $channel = $logConfig['channel'] ?? 'app';

        // Validate level early for a clear error message.
        LogLevelSeverity::validate($level);

        $inner = match ($driver) {
            'file'    => self::buildFileLogger($logConfig, $projectDir, $channel),
            'systemd' => new SystemdLogger($channel),
            'syslog'  => new SyslogLogger(
                            $logConfig['ident']    ?? 'ktrix',
                            $logConfig['facility'] ?? LOG_USER,
                            $channel,
                         ),
            'null'    => new NullLogger(),
            default   => throw new \RuntimeException(
                            sprintf(
                                'Unknown log driver "%s". Supported drivers: file, systemd, syslog, null.',
                                $driver
                            )
                         ),
        };

        return new LevelFilterLogger($inner, $level);
    }

    private static function buildFileLogger(array $logConfig, string $projectDir, string $channel): FileLogger
    {
        $path = $logConfig['path'] ?? null;

        if ($path === null || $path === '') {
            $path = $projectDir . '/var/log';
        }

        return new FileLogger($path, $channel);
    }
}