<?php

namespace App\Services;

use App\Exceptions\DockerNotInstalled;
use App\Models\Server;
use InvalidArgumentException;
use RuntimeException;

/**
 * Manage the containers running ON a fleet server, agentlessly over SSH. Every docker call goes
 * through FleetService::runPrivileged (base64 transport → shell-injection-safe); every container
 * id/name is validated before interpolation so a crafted name can neither inject a command nor a
 * leading-dash argument. Mirrors the FleetService::serviceAction discipline.
 */
class DockerService
{
    public const ACTIONS = ['start', 'stop', 'restart', 'pause', 'unpause'];

    /**
     * A non-interactive SSH exec (and sudo's secure_path) often has a MINIMAL PATH (~/usr/bin:/bin),
     * so `docker` installed in /usr/local/bin (get.docker.com), /snap/bin (snap), or /usr/sbin isn't
     * found → "sh: docker: not found" even though it IS installed. Prepend the common bin dirs to
     * every docker call so the binary is located regardless of the login shell's PATH. Single-quoted
     * so `${PATH:+:$PATH}` reaches the remote shell literally (not interpolated by PHP).
     */
    private const PATH_PREFIX = 'export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin${PATH:+:$PATH}; ';

    public function __construct(private FleetService $fleet) {}

    public function available(Server $server): bool
    {
        $res = $this->fleet->runPrivileged($server, self::PATH_PREFIX.'command -v docker >/dev/null 2>&1 && echo yes || echo no');

        return trim($res['output']) === 'yes';
    }

    /**
     * @return array<int, array{id:string,name:string,image:string,state:string,status:string,ports:string}>
     */
    public function containers(Server $server): array
    {
        // Tab-separated columns (NOT `{{json .}}`): works on much older Docker AND avoids a JSON
        // key-casing dependency. `.State` was added late, so we derive state from `.Status` text —
        // this is the whole reason a modern-only `{{json .}}` could return nothing on an older host.
        $fmt = '{{.ID}}\t{{.Names}}\t{{.Image}}\t{{.Status}}\t{{.Ports}}';
        $res = $this->fleet->runPrivileged($server, self::PATH_PREFIX."docker ps -a --format '{$fmt}'");

        if (! $res['ok']) {
            $err = $this->firstLine($res['output']);
            // Distinguish "docker binary absent" (a native server, no runtime) from a real fault
            // right here, so callers get the honest "not installed" state from THIS single `docker
            // ps` call instead of paying a second SSH round-trip on a separate available() probe.
            if (preg_match('/docker:\s.*not found/i', $err)) {
                throw new DockerNotInstalled($err);
            }
            // Surface the REAL reason (daemon down / permission / rootless socket) rather than a
            // misleading empty list — the component shows this instead of "no containers".
            throw new RuntimeException($err ?: 'docker ps failed');
        }

        $out = [];
        foreach (preg_split('/\r?\n/', trim($res['output'])) ?: [] as $line) {
            if (trim($line) === '') {
                continue;
            }
            $p = explode("\t", $line);
            $status = trim($p[3] ?? '');
            $name = trim($p[1] ?? '');
            $out[] = [
                'id' => trim($p[0] ?? ''),
                'name' => $name,
                'display' => self::displayName($name),
                'image' => trim($p[2] ?? ''),
                'state' => $this->stateFromStatus($status),
                'status' => $status,
                'ports' => trim($p[4] ?? ''),
            ];
        }

        return $out;
    }

    /**
     * Display-only container name: strip the compose replica suffix ("clusev-app-1" -> "clusev-app").
     * NEVER use for docker commands — actions/logs keep the real name/id.
     */
    public static function displayName(string $name): string
    {
        return preg_replace('/-\d+$/', '', $name) ?: $name;
    }

    /** Derive a coarse state from docker's Status text (portable across versions that lack .State). */
    private function stateFromStatus(string $status): string
    {
        $s = strtolower($status);

        return match (true) {
            str_contains($s, '(paused)') => 'paused',
            str_starts_with($s, 'up') => 'running',
            str_starts_with($s, 'created') => 'created',
            str_starts_with($s, 'restarting') => 'restarting',
            default => 'exited', // Exited / Dead / Removal
        };
    }

    private function firstLine(string $out): string
    {
        return trim(preg_split('/\r?\n/', trim($out))[0] ?? '');
    }

    public function containerAction(Server $server, string $id, string $op): array
    {
        if (! in_array($op, self::ACTIONS, true)) {
            throw new InvalidArgumentException('Unbekannte Aktion.');
        }
        $this->assertValidRef($id);

        $res = $this->fleet->runPrivileged($server, self::PATH_PREFIX."docker {$op} {$id}");

        return ['ok' => $res['ok'], 'output' => trim($res['output'])];
    }

    public function logs(Server $server, string $id, int $lines = 200): string
    {
        $this->assertValidRef($id);
        $lines = max(1, min(2000, $lines));

        // Cap by BYTES too (not just lines): one huge line or a binary-ish log could otherwise bloat
        // the response or, via invalid UTF-8, break Livewire's JSON snapshot. head -c bounds it, and
        // mb_scrub drops any invalid byte sequence before it reaches a Livewire public property.
        $res = $this->fleet->runPrivileged($server, self::PATH_PREFIX."docker logs --tail {$lines} {$id} 2>&1 | head -c 262144");

        return mb_scrub(trim($res['output']), 'UTF-8');
    }

    /**
     * @return array<int, array{name:string,status:string}>
     */
    public function composeStacks(Server $server): array
    {
        $res = $this->fleet->runPrivileged($server, self::PATH_PREFIX.'docker compose ls --format json 2>/dev/null');
        if (! $res['ok']) {
            return [];
        }

        $rows = json_decode(trim($res['output']), true);
        if (! is_array($rows)) {
            return [];
        }

        return array_map(fn ($r) => [
            'name' => (string) ($r['Name'] ?? ''),
            'status' => (string) ($r['Status'] ?? ''),
        ], array_values(array_filter($rows, 'is_array')));
    }

    /**
     * A container id or name — hex id or a docker name. MUST start alphanumeric (blocks a leading
     * dash = argument injection) and contain only [\w.-] (no shell metacharacters).
     */
    private function assertValidRef(string $ref): void
    {
        // \A ... \z (not ^...$): \z anchors the ABSOLUTE end so a trailing newline can't sneak past.
        if (! preg_match('/\A[a-zA-Z0-9][\w.-]*\z/', $ref)) {
            throw new InvalidArgumentException('Ungueltige Container-Referenz.');
        }
    }
}