<?php
namespace Grav\Plugin;

use Grav\Common\Data\ValidationException;
use Grav\Common\Plugin;
use RocketTheme\Toolbox\Event\Event;

class CacheOnSavePlugin extends Plugin
{
    public static function getSubscribedEvents(): array
    {
        return [
            // Runs before add-page-by-form's onFormProcessed (page write), so it
            // can inject the write target and abort the submit by failing validation.
            'onFormValidationProcessed' => ['onFormValidationProcessed', 0],
            // Priority -100 so this runs AFTER add-page-by-form's onFormProcessed
            // (priority 0) has created the page and copied the uploaded files —
            // we reorder those files, then clear the page-tree cache.
            'onFormProcessed' => ['onFormProcessed', -100],
        ];
    }

    /**
     * Server-authoritative active-trip parent injection.
     *
     * The post form no longer hardcodes `pageconfig.parent`; instead the write
     * target is derived from `site.active_trip` at submit time and injected into
     * the form data. add-page-by-form reads `$form->value()->toArray()['parent']`
     * (add-page-by-form.php:521) and honours it over any pageconfig/header parent.
     *
     * Fail closed: if `active_trip` is unset/empty we throw a ValidationException
     * so the `add_page` action never runs. Merely leaving `parent` unset is unsafe —
     * with `pageconfig.parent` removed, add-page-by-form's `getParentPage('')`
     * resolves to the /post page itself and the entry would silently land there.
     */
    public function onFormValidationProcessed(Event $event): void
    {
        $form = $event['form'];
        if (!$form || $form->getName() !== 'new-entry') {
            return;
        }

        $activeTrip = $this->grav['config']->get('site.active_trip');
        $activeTrip = is_string($activeTrip) ? trim($activeTrip) : '';

        if ($activeTrip === '') {
            throw new ValidationException('No active trip is set — cannot post an entry. Set site.active_trip first.');
        }

        $form->setData('parent', $this->resolveDailiesParent($activeTrip));
    }

    /**
     * Normalise `active_trip` to its dailies container route.
     *
     * Accepts either a full route ("/trips/italy-2026-demo") or a bare slug
     * ("italy-2026-demo") and returns "/trips/<slug>/dailies".
     */
    private function resolveDailiesParent(string $activeTrip): string
    {
        $trip = trim($activeTrip, '/');
        if (strpos($trip, 'trips/') !== 0) {
            $trip = 'trips/' . $trip;
        }

        return '/' . $trip . '/dailies';
    }

    /**
     * The photo order the user arranged in the form, sent explicitly by
     * post-form.js as a JSON array of filenames in the dedicated
     * data[photo_order] input. FilePond does not re-sequence its own submitted
     * inputs on reorder, so this is the only reliable source of the drag order.
     * Read straight from $_POST as a top-level key (not under data[]), so Grav's
     * form never captures it and it never lands in the entry frontmatter.
     */
    private function orderFromPost(): array
    {
        $raw = $_POST['photo_order'] ?? null;
        if (!is_string($raw) || $raw === '') {
            return [];
        }
        $decoded = json_decode($raw, true);
        if (!is_array($decoded)) {
            return [];
        }
        $names = [];
        foreach ($decoded as $name) {
            if (is_string($name) && $name !== '') {
                $names[] = basename(str_replace('\\', '/', $name));
            }
        }
        return $names;
    }

    public function onFormProcessed(Event $event): void
    {
        $form = $event['form'];
        if (!$form || $form->getName() !== 'new-entry') {
            return;
        }

        // Reorder the just-copied photos to match the order the user arranged in
        // the form (FilePond drag). Best-effort: any failure logs and is skipped
        // so a post is never lost over cosmetics.
        try {
            $this->reorderPhotos();
        } catch (\Throwable $e) {
            $this->grav['log']->warning('cache-on-save: photo reorder skipped — ' . $e->getMessage());
        }

        $this->grav['cache']->deleteAll();
    }

    /**
     * Rename the uploaded photos to photo-1..N in the submitted (drag) order.
     *
     * The published entry lists media in filename order and treats the first as
     * the hero (see partials/entry-journal + entry-story), so a deterministic
     * photo-N naming is what makes the arranged order stick. copyFiles() writes
     * each file under its unsanitised client filename, and post-form.js sends the
     * drag order via the top-level `photo_order` POST key (orderFromPost) — so we
     * can map each on-disk file to its final photo-N slot.
     */
    private function reorderPhotos(): void
    {
        $names = $this->orderFromPost();
        if (count($names) < 1) {
            return; // nothing uploaded
        }

        $activeTrip = $this->grav['config']->get('site.active_trip');
        $activeTrip = is_string($activeTrip) ? trim($activeTrip) : '';
        if ($activeTrip === '') {
            return;
        }
        $slug = preg_replace('#^/?trips/#', '', trim($activeTrip, '/'));
        $slug = preg_replace('#/.*$#', '', $slug);

        $dir = $this->findEntryFolder($slug, $names);
        if ($dir === null) {
            return; // couldn't confidently locate the new entry folder
        }

        // Two-phase rename via temp names so a target (photo-2.jpg) can't clobber
        // a not-yet-moved source of the same name.
        $planned = [];
        $i = 1;
        foreach ($names as $name) {
            $src = $dir . DIRECTORY_SEPARATOR . $name;
            if (!is_file($src)) {
                continue; // skip anything not actually on disk
            }
            $ext = strtolower(pathinfo($name, PATHINFO_EXTENSION)) ?: 'jpg';
            $tmp = $dir . DIRECTORY_SEPARATOR . '.reorder-tmp-' . $i . '.' . $ext;
            $final = $dir . DIRECTORY_SEPARATOR . 'photo-' . $i . '.' . $ext;
            if ($src === $final) {
                $i++;
                continue; // already correctly named
            }
            @rename($src, $tmp);
            $planned[] = [$tmp, $final];
            $i++;
        }
        foreach ($planned as [$tmp, $final]) {
            if (is_file($tmp)) {
                @rename($tmp, $final);
            }
        }
    }

    /**
     * Locate the freshly-created entry folder: the child of the active trip's
     * dailies directory that contains all of the uploaded files. Matching by the
     * exact uploaded filenames avoids re-deriving add-page-by-form's slug logic.
     */
    private function findEntryFolder(string $slug, array $names): ?string
    {
        $pagesRoot = rtrim(USER_DIR, '/\\') . '/pages';
        $dailies = null;
        foreach (glob($pagesRoot . '/*trips*', GLOB_ONLYDIR) ?: [] as $tripsDir) {
            foreach (glob($tripsDir . '/*', GLOB_ONLYDIR) ?: [] as $tripDir) {
                $base = basename($tripDir);
                if ($base === $slug || preg_match('/(^|\.)' . preg_quote($slug, '/') . '$/', $base)) {
                    $found = glob($tripDir . '/*dailies*', GLOB_ONLYDIR) ?: [];
                    if ($found) {
                        $dailies = $found[0];
                        break 2;
                    }
                }
            }
        }
        if ($dailies === null) {
            return null;
        }

        foreach (glob($dailies . '/*', GLOB_ONLYDIR) ?: [] as $child) {
            $allPresent = true;
            foreach ($names as $name) {
                if (!is_file($child . DIRECTORY_SEPARATOR . $name)) {
                    $allPresent = false;
                    break;
                }
            }
            if ($allPresent) {
                return $child;
            }
        }
        return null;
    }
}