#!/usr/bin/env php
<?php

declare(strict_types=1);

/**
 * run.php — Self-hosted Arboricx PHP host shell.
 *
 * Usage:
 *   php run.php run <bundle.arboricx> <arg> [arg ...]
 *   php run.php inspect <bundle.arboricx>
 *
 * The "run" command:
 *   1. Reads the .arboricx bundle as raw bytes
 *   2. Encodes bundle bytes as a Tree Calculus byte list
 *   3. Encodes each host argument (string or number)
 *   4. Calls runArboricxToString via the hardcoded kernel
 *   5. Unwraps ok/err, then Host ABI envelope
 *   6. Decodes the string payload
 *
 * This is a minimal host shell — it does NOT parse Arboricx bundles itself.
 * The kernel handles bundle parsing internally.
 */

require __DIR__ . '/src/functions.php';
require __DIR__ . '/src/codecs.php';
require __DIR__ . '/src/kernel.php';

use Arboricx\Node;
use function Arboricx\{app, reduce, ofString, ofNumber, ofBytes, ofList,
    formatTree, unwrapResult, unwrapHostValue, decodeHostPayload,
    getRunArboricxToString};

// ── Commands ─────────────────────────────────────────────────────────────────

function readBundle(string $path): string
{
    if (!file_exists($path)) {
        fwrite(STDERR, "Error: bundle not found: $path\n");
        exit(1);
    }
    $bytes = file_get_contents($path);
    if ($bytes === false) {
        fwrite(STDERR, "Error: could not read bundle: $path\n");
        exit(1);
    }
    return $bytes;
}

function cmdRun(string $bundlePath, array $args): void
{
    $bundleBytes = readBundle($bundlePath);

    $kernel = getRunArboricxToString();
    if ($kernel === null) {
        fwrite(STDERR, "Error: runArboricxToString kernel not configured\n");
        exit(1);
    }

    $bundleTree = ofBytes($bundleBytes);

    $argTrees = [];
    foreach ($args as $arg) {
        $argTrees[] = encodeArg($arg);
    }
    $argsTree = ofList($argTrees);

    // Kernel application: runArboricxToString bundle args
    $expr = app(app($kernel, $bundleTree), $argsTree);
    fwrite(STDERR, "Reducing kernel application...\n");
    $result = reduce($expr, 1_000_000_000_000);

    // The kernel returns an ok/err pair.  On ok, the value is a
    // Host ABI envelope: Fork(tag_number, payload_tree).
    [$kind, $value, $rest] = unwrapResult($result);
    if ($kind === 'error') {
        fwrite(STDERR, "Error detail: $rest\n");
        exit(1);
    }
    if ($kind === 'err') {
        [$ok2, $code] = Arboricx\toNumber($value);
        $codeStr = $ok2 ? (string)$code : formatTree($value);
        fwrite(STDERR, "Arboricx error code: $codeStr\n");
        fwrite(STDERR, "Rest: " . formatTree($rest) . "\n");
        exit(1);
    }

    [$tag, $payload] = unwrapHostValue($value);

    try {
        $decoded = decodeHostPayload($tag, $payload);
        echo $decoded['value'] . "\n";
    } catch (\Throwable $e) {
        fwrite(STDERR, "Host ABI decode error: " . $e->getMessage() . "\n");
        fwrite(STDERR, "Raw tag: $tag, payload: " . formatTree($payload) . "\n");
        exit(1);
    }
}

function encodeArg(string $arg): Node
{
    return ctype_digit($arg) ? ofNumber((int)$arg) : ofString($arg);
}

function cmdInspect(string $bundlePath): void
{
    $bundleBytes = readBundle($bundlePath);
    $bytes = strlen($bundleBytes);
    echo "Bundle: $bundlePath\n";
    echo "Size: $bytes bytes\n";

    // Run with no arguments to see the default export
    $kernel = getRunArboricxToString();
    if ($kernel === null) {
        fwrite(STDERR, "Warning: kernel not configured, skipping execution\n");
        return;
    }

    $bundleTree = ofBytes($bundleBytes);
    $emptyArgs = ofList([]);
    $result = reduce(app(app($kernel, $bundleTree), $emptyArgs), 10_000);
    [$kind, $value, $rest] = unwrapResult($result);

    if ($kind === 'ok') {
        echo "\nResult (ok):\n";
        try {
            [$tag, $payload] = unwrapHostValue($value);
            $decoded = decodeHostPayload($tag, $payload);
            echo "  Tag: $tag (type: " . $decoded['type'] . ")\n";
            echo "  Value: " . $decoded['value'] . "\n";
        } catch (\Throwable $e) {
            echo "  Raw: " . formatTree($value) . "\n";
        }
    } else {
        echo "\nResult (err):\n";
        [$ok, $code] = Arboricx\toNumber($value);
        echo "  Code: " . ($ok ? (string)$code : formatTree($value)) . "\n";
    }
}

// ── Main ─────────────────────────────────────────────────────────────────────

$argv = $_SERVER['argv'] ?? [];
$argc = $_SERVER['argc'] ?? 0;

if ($argc < 2) {
    echo "Arboricx PHP Host Shell\n";
    echo "\nUsage:\n";
    echo "  php run.php run <bundle.arboricx> [args...]\n";
    echo "  php run.php inspect <bundle.arboricx>\n";
    exit(0);
}

$command = $argv[1];
switch ($command) {
    case 'run':
        if ($argc < 3) {
            fwrite(STDERR, "Usage: php run.php run <bundle.arboricx> [args...]\n");
            exit(1);
        }
        cmdRun($argv[2], array_slice($argv, 3));
        break;
    case 'inspect':
        if ($argc < 3) {
            fwrite(STDERR, "Usage: php run.php inspect <bundle.arboricx>\n");
            exit(1);
        }
        cmdInspect($argv[2]);
        break;
    default:
        echo "Unknown command: $command\n";
        echo "Usage: php run.php run|inspect ...\n";
        exit(1);
}