<?php

namespace NoccyLabs\Serverctl\Container;

use RuntimeException;

class ContainerManager
{

    private string $dataPath;

    private string $stateFile;

    private array $autoEnv = [];

    private array $serverEnvs = [];

    public function __construct(?string $dataPath=null)
    {
        $this->dataPath = $dataPath ?? (getenv("HOME")."/.var/serverctl");
        $this->stateFile = $this->dataPath . "/state.json";
        $this->setupAutoEnv();
        $this->setupServerEnvs();
    }

    private function setupServerEnvs()
    {
        $file = getenv("HOME")."/.serverenvs";

        if (!file_exists($file)) {
            $this->serverEnvs = [];
            return;
        }

        $parsed = parse_ini_file($file, true);

        $this->serverEnvs = $parsed;
    }

    private function setupAutoEnv()
    {
        $ifs = net_get_interfaces();
        if ($ifs) {
            $dockerHostIp = null;
            if (array_key_exists('docker0', $ifs)) {
                foreach ($ifs['docker0']['unicast'] as $uc) {
                    if ($uc['family'] == 2) {
                        $dockerHostIp = $uc['address'];
                        break;
                    }
                }
            } else {
                // Find a usable interface
                foreach ($ifs as $if=>$conf) {
                    if (!array_key_exists('unicast', $conf)) continue;
                    foreach ($conf['unicast'] as $uc) {
                        if ($uc['family'] == 2) {
                            $dockerHostIp = $uc['address'];
                            break;
                        }
                    }
                }
            }
            $this->autoEnv['DOCKER_HOST'] = $dockerHostIp;
        }
    }

    private function updateStateFile(string $instanceId, ?array $options)
    {
        if (!file_exists($this->stateFile)) {
            touch($this->stateFile);
        }
        $fd = fopen($this->stateFile, 'r+');
        if (!flock($fd, LOCK_EX)) {
            throw new \RuntimeException("flock fail");
        }
        
        // Read the state from the file, seek to end first to get size
        fseek($fd, 0, SEEK_END);
        $flen = ftell($fd);
        fseek($fd, 0, SEEK_SET);
        if ($flen > 0) {
            $body = fread($fd, $flen);
            // Parse the state
            $state = (array)((@json_decode($body, true))??[]);
        } else {
            $state = [];
        }

        // Update node in state
        if ($options === null) {
            unset($state[$instanceId]);
        } else {
            $state[$instanceId] = $options;
        }

        // Reencode the state, truncate the file and write it
        $body = json_encode($state, JSON_PRETTY_PRINT|JSON_UNESCAPED_SLASHES);
        fseek($fd, 0, SEEK_SET);
        ftruncate($fd, 0);
        fwrite($fd, $body);
        
        // TODO: release lock
        flock($fd, LOCK_UN);
    }

    /**
     * Start a service
     * 
     * Instance options:
     *   name: Instance name (default)
     *   portoffset: Port number offset (0)
     * 
     * @param array $service The service definition from the registry  
     * @param array $options Instance options
     */
    public function startService(array $service, array $options)
    {
        $args = [];

        $serviceName = $service['name'];
        $instanceName = $options['name']??'default';
        $portOffset = intval($options['portoffset']??0);

        $temporary = $option['temporary']??false;
        if ($temporary) {
            $instanceName = sprintf("%04x%04x", rand(0,0xFFFF), rand(0,0xFFFF));
        }

        $containerName = "sm_".$serviceName."_".$instanceName;

        $args[] = 'run';
        $args[] = '--rm'; // remove container after run
        $args[] = '-d';
        $args[] = '--name';
        $args[] = $containerName;

        // Map the ports
        $ports = (array)($service['ports']??[]);
        $mappedPorts = [];
        foreach ($ports as $port) {
            $portNumber = intval($port['port']) + $portOffset;
            $target = array_key_exists('target',$port)?intval($port['target']):intval($port['port']);
            $proto = $port['proto']??"tcp";
            $args[] = '-p';
            $args[] = $portNumber.":".$target."/".$proto;
            $mappedPorts[$port['info']] = $portNumber."/".$proto;
        }

        // Get the paths to persist
        $volumes = (array)($service['persistence']??[]);
        $volumePath = $this->getServiceDataPath($service)."/".$instanceName;
        foreach ($volumes as $volume) {
            // volume { path, hint }
            $path = $volume['path'];
            $hint = $volume['hint'] ?? crc32($path);
            $args[] = '-v'; // add volume
            $args[] = $volumePath."/".$hint.":".$path;
        }

        $parsedEnv = [];

        // Prepared environment from serviceenvs
        $key = $serviceName . ":" . $instanceName;
        if (array_key_exists($key, $this->serverEnvs)) {
            foreach ($this->serverEnvs[$key] as $env=>$value) {
                $value = $this->expandString($value);
                array_push($args, "-e", sprintf("%s=%s", $env, $value));
                $parsedEnv[$env] = $value;
            }
        }

        // Get environment
        $envs = (array)($service['environment']??[]);
        foreach ($envs as $env=>$value) {
            if (array_key_exists($env, $parsedEnv)) continue;
            $args[] = '-e';
            $envval = getenv($env, true);
            if ($envval) $value = $envval;
            $value = $this->expandString($value);
            $args[] = sprintf("%s=%s", $env, $value);
            $parsedEnv[$env] = $value;
        }

        $args[] = $service['image'];

        $cmdl = 'docker '.join(' ',array_map('escapeshellarg', $args));
        
        //echo "$ {$cmdl}\n";

        exec($cmdl, $out, $ret);
        if ($ret != 0) {
            echo join("\n",$out)."\n";
            throw new RuntimeException("Docker returned non-zero exit code");
        }

        $this->updateStateFile($containerName, [
            'command' => $cmdl,
            'instance' => $instanceName,
            'environment' => $parsedEnv,
            'service' => $service,
            'ports' => $mappedPorts,
            'temporary' => $temporary,
        ]);

        return [
            'ports' => $mappedPorts
        ];

    }

    /**
     * Stop a service
     */
    public function stopService(array $service, string $instanceName)
    {
        $args = [];

        $serviceName = $service['name'];
        $containerName = "sm_".$serviceName."_".$instanceName;

        $args[] = 'stop';
        $args[] = $containerName;

        $cmdl = 'docker '.join(' ',array_map('escapeshellarg', $args));

        //echo "$ {$cmdl}\n";
        exec($cmdl, $out, $ret);
        if ($ret != 0) {
            echo join("\n",$out)."\n";
            throw new RuntimeException("Docker returned non-zero exitcode");
        }

        $this->updateStateFile($containerName, null);

    }

    public function execute(array $service, string $instanceName, array $command)
    {
        $args = [];

        $serviceName = $service['name'];
        $instanceName = $options['name']??'default';
        $containerName = "sm_".$serviceName."_".$instanceName;

        $args[] = 'exec';
        $args[] = '-it';
        $args[] = $containerName;

        array_push($args, ...$command);

        $cmdl = 'docker '.join(' ',array_map('escapeshellarg', $args));

        $cmdl = preg_replace_callback('<\$\{(.+?)\}>', function ($v) use ($service) {
            return $service['environment'][$v[1]]??null;
        }, $cmdl);

        echo "$ {$cmdl}\n";
        passthru($cmdl);
        
    }

    /**
     * Get running services
     */
    public function getRunningServices(): array
    {
        if (!file_exists($this->stateFile)) {
            return [];
        }

        $fd = fopen($this->stateFile, 'r+');
        if (!flock($fd, LOCK_SH)) {
            throw new \RuntimeException("flock fail");
        }
        
        // Read the state from the file, seek to end first to get size
        fseek($fd, 0, SEEK_END);
        $flen = ftell($fd);
        fseek($fd, 0, SEEK_SET);

        $ret = [];
        if ($flen > 0) {
            $body = fread($fd, $flen);
            // Parse the state
            $ret = (array)((@json_decode($body, true))??[]);
        } else {
            return [];
        }

        return $ret;
    }

    public function getServiceDataPath(array $service)
    {
        return $this->dataPath."/".$service['name'];
    }

    private function expandString(string $input): string
    {
        return preg_replace_callback('<\$\{(.+?)\}>i', function ($m) {
            $k = $m[1];
            if (array_key_exists($k, $this->autoEnv)) {
                return $this->autoEnv[$k];
            }
            return getenv($k);
        }, $input);
    }

}