#!/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>
 *   php run.php repl
 *
 * 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 function Arboricx\{app, apply_, reduce, ofString, ofNumber, ofBytes, ofList,
    formatTree, decodeResult, unwrapResult,
    unwrapHostValue, decodeHostPayload,
    isLeaf, isStem, isFork,
    HOST_STRING_TAG, HOST_NUMBER_TAG, HOST_BOOL_TAG,
    HOST_LIST_TAG, HOST_BYTES_TAG, HOST_TREE_TAG,
    getRunArboricxToString};

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

function debugTime(string $label): void
{
    static $start = null;
    static $last = null;
    $now = microtime(true);
    if ($start === null) {
        $start = $now;
        $last = $now;
    }
    fwrite(STDERR, sprintf("[%.3fs +%.3fs] %s\n", $now - $start, $now - $last, $label));
    $last = $now;
}

function cmdRun(string $bundlePath, array $args): void
{
    debugTime('start');

    if (!file_exists($bundlePath)) {
        fwrite(STDERR, "Error: bundle file not found: $bundlePath\n");
        exit(1);
    }
    $bundleBytes = file_get_contents($bundlePath);
    debugTime('read bundle bytes');
    if ($bundleBytes === false) {
        fwrite(STDERR, "Error: could not read bundle file: $bundlePath\n");
        exit(1);
    }

    $kernel = getRunArboricxToString();
    debugTime('loaded kernel');
    if ($kernel === null) {
        fwrite(STDERR, "Error: runArboricxToString kernel not configured (empty ternary string)\n");
        fwrite(STDERR, "Set KERNEL_RUN_ARBORICX_TO_STRING constant in kernel.php\n");
        exit(1);
    }

    $bundleTree = ofBytes($bundleBytes);
    debugTime('encoded bundle bytes');

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

    $expr = app(app($kernel, $bundleTree), $argsTree);
    debugTime('built expression');

    fwrite(STDERR, "Reducing kernel application...\n");
    $result = reduce($expr, 1_000_000);
    debugTime('reduced kernel application');

    [$kind, $value, $rest] = unwrapResult($result);
    debugTime('unwrapped 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);
    debugTime('unwrapped host value');

    try {
        $decoded = decodeHostPayload($tag, $payload);
        debugTime('decoded 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);
    }
}

/**
 * Encode a command-line argument into a Tree Calculus value.
 *
 * - Numeric strings (digits only) → tree number
 * - Everything else → tree string
 */
function encodeArg(string $arg): int
{
    if (ctype_digit($arg) || ($arg !== '0' && preg_match('/^-?\d+$/', $arg))) {
        return ofNumber((int)$arg);
    }
    return ofString($arg);
}

function cmdInspect(string $bundlePath): void
{
    // Minimal inspection: just read the bundle as bytes and print its size.
    // Full parsing is done by the kernel, not the host shell.
    if (!file_exists($bundlePath)) {
        fwrite(STDERR, "Error: bundle file not found: $bundlePath\n");
        exit(1);
    }
    $bundleBytes = file_get_contents($bundlePath);
    if ($bundleBytes === false) {
        fwrite(STDERR, "Error: could not read bundle file: $bundlePath\n");
        exit(1);
    }

    $bytes = strlen($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";
    }
}

function cmdRepl(): void
{
    echo "Arboricx PHP REPL\n";
    echo "Commands:\n";
    echo "  run <bundle> [args...]   — Run a bundle\n";
    echo "  inspect <bundle>         — Inspect a bundle\n";
    echo "  exit                     — Exit\n";
    echo "\n";

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

    while (true) {
        $prompt = "arboricx> ";
        fwrite(STDOUT, $prompt);
        $line = trim(fgets(STDIN));
        if ($line === '' || $line === 'exit' || $line === 'quit') {
            break;
        }

        $parts = preg_split('/\s+/', $line, 2);
        if (!$parts) {
            continue;
        }

        $cmd = $parts[0];
        switch ($cmd) {
            case 'run':
                if (!isset($parts[1])) {
                    fwrite(STDERR, "Usage: run <bundle> [args...]\n");
                    break;
                }
                $cmdRun($parts[1], array_slice($parts, 2));
                break;
            case 'inspect':
                if (!isset($parts[1])) {
                    fwrite(STDERR, "Usage: inspect <bundle>\n");
                    break;
                }
                cmdInspect($parts[1]);
                break;
            case 'help':
                echo "Commands:\n";
                echo "  run <bundle> [args...]   — Run a bundle\n";
                echo "  inspect <bundle>         — Inspect a bundle\n";
                echo "  exit                     — Exit\n";
                break;
            default:
                fwrite(STDERR, "Unknown command: $cmd\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";
    echo "  php run.php repl\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;
    case 'repl':
        cmdRepl();
        break;
    default:
        echo "Unknown command: $command\n";
        echo "Usage: php run.php run|inspect|repl ...\n";
        exit(1);
}