<?php
namespace Grav\Plugin;

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

require_once __DIR__ . '/classes/EntryScopeGuard.php';

use Grav\Plugin\Shared\EntryScopeGuard;

class CacheOnSavePlugin extends Plugin
{
    /**
     * onFormProcessed fires once per `process:` action (add_page, upload, message,
     * reset — 4x for the post form). Photo reconciliation must run exactly once:
     * the first pass renames the kept photos to photo-1..N, so a second pass with
     * the same manifest would see those renamed files as "unlisted" and delete
     * them. This latches after the first run (the plugin instance persists for the
     * request); the first fire is the `add_page` action, after add-page-by-form
     * (priority 0) has created the page and copied files, so files are present.
     */
    private bool $photosReconciled = false;

    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));

        // One shared /post form drives both create and edit (KTD1). add-page-by-form
        // reads overwrite_mode from the /post page header's pageconfig (not form
        // data), so we toggle it here per submit.
        $editPath = $this->editPathFromForm($form);

        if ($editPath === '') {
            // CREATE — left untouched (any site.login user): overwrite_mode:false
            // so stock add-page-by-form falls through to slug_field (date,title)
            // and writes a fresh dated folder.
            $this->setOverwriteMode('false');
            return;
        }

        // EDIT — enforce R6 server-side (KTD6) BEFORE allowing an in-place write.
        // Fail closed (ValidationException) so the add_page action never runs.
        // The UI only renders Edit for the owner on the active trip, but that gate
        // is cosmetic; this is the authoritative check.
        if (!EntryScopeGuard::isOwner($this->grav)) {
            throw new ValidationException('You are not allowed to edit journal entries.');
        }
        $segment = EntryScopeGuard::segmentFromEditPath($editPath);
        if (EntryScopeGuard::resolveActiveDailyChild($this->grav, $segment) === null) {
            // Unsafe/traversal segment, no active trip, missing page, or a target
            // outside the active trip's dailies — all rejected identically.
            throw new ValidationException('That entry is not editable here — it is not in the active trip.');
        }
        $this->setOverwriteMode('edit');
    }

    /**
     * The hidden edit_path form field, trimmed. Empty string when creating a new
     * entry; the entry's `<route>/entry.md` path when editing (set by post-form.js).
     */
    private function editPathFromForm($form): string
    {
        $value = $form->value('edit_path');
        return is_string($value) ? trim($value) : '';
    }

    /**
     * Override add-page-by-form's overwrite_mode by mutating the current (/post)
     * page header's pageconfig. add-page-by-form reads
     * `$grav['page']->header()->pageconfig['overwrite_mode']` (add-page-by-form.php
     * :385) from the same page singleton, and Page::header() returns a cached
     * instance, so this write is visible when its onFormProcessed runs afterwards.
     */
    private function setOverwriteMode(string $mode): void
    {
        $page = $this->grav['page'] ?? null;
        if (!$page) {
            return;
        }
        $header = $page->header();
        $pageconfig = (isset($header->pageconfig) && is_array($header->pageconfig)) ? $header->pageconfig : [];
        $pageconfig['overwrite_mode'] = $mode;
        $header->pageconfig = $pageconfig;
    }

    /**
     * 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;
        }

        // Reconcile the entry's photos to the order the owner arranged in the form
        // (FilePond drag). On create this only renumbers the just-copied uploads;
        // on edit (M2) it also removes any photo the owner dropped and renumbers
        // the surviving set so the first file is the cover. Runs ONCE per submit
        // (see $photosReconciled) — a second pass would delete the just-renamed
        // photo-N files as "unlisted". Best-effort: any failure logs and is
        // skipped so a post is never lost over cosmetics.
        if (!$this->photosReconciled) {
            $this->photosReconciled = true;
            try {
                $this->reconcilePhotos($form);
            } catch (\Throwable $e) {
                $this->grav['log']->warning('cache-on-save: photo reconcile skipped — ' . $e->getMessage());
            }
        }

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

    /**
     * Reconcile the entry's photo files to the submitted (drag) order.
     *
     * The published entry lists media in filename order and treats the first as
     * the hero/cover (see partials/entry-journal + entry-story), so a deterministic
     * photo-N naming is what makes the arranged order stick. post-form.js sends the
     * final ordered set via the top-level `photo_order` POST key (orderFromPost):
     * on create these are the just-uploaded client filenames; on edit (M2) the mix
     * of surviving existing photos (loaded into FilePond as local items) plus any
     * new uploads, in the arranged order.
     *
     * Create: fuzzily locate the fresh folder by its uploaded filenames, then
     * renumber. Edit: locate the folder authoritatively through the page tree via
     * the shared scope guard (findEntryFolder is unsafe once files are the generic
     * photo-N.jpg — many entries share those names), delete any image the owner
     * dropped (not in the manifest), then renumber the survivors.
     *
     * Fail-safe: an empty manifest reconciles nothing (photos are left untouched),
     * so a missing/failed `photo_order` on edit never wipes an entry's images.
     */
    private function reconcilePhotos($form): void
    {
        $names = $this->orderFromPost();
        if (count($names) < 1) {
            return; // nothing submitted — leave the entry's photos untouched
        }

        $editPath = $this->editPathFromForm($form);
        if ($editPath !== '') {
            // EDIT — resolve the target folder through the page tree (shared guard),
            // then prune dropped photos before renumbering the survivors.
            $segment = EntryScopeGuard::segmentFromEditPath($editPath);
            $page = EntryScopeGuard::resolveActiveDailyChild($this->grav, $segment);
            if ($page === null) {
                return; // out of scope / unresolvable — the save guard already ran
            }
            $dir = $page->path();
            $this->deleteUnlistedImages($dir, $names);
        } else {
            // CREATE — locate the fresh folder by the set of uploaded filenames.
            $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
            }
        }

        $this->renumberPhotos($dir, $names);
    }

    /**
     * Delete every image file in $dir whose basename is not in $keep (the manifest
     * of photos the owner kept). Only touches known image extensions — never the
     * entry .md or any other file — and clears any Grav media sidecar so a stale
     * `.meta.yaml` can't resurrect a removed image.
     */
    private function deleteUnlistedImages(string $dir, array $keep): void
    {
        $keepSet = array_flip($keep);
        $imageExts = ['jpg', 'jpeg', 'png', 'gif', 'webp', 'heic', 'heif'];
        foreach (glob($dir . DIRECTORY_SEPARATOR . '*') ?: [] as $path) {
            if (!is_file($path)) {
                continue;
            }
            $base = basename($path);
            $ext = strtolower(pathinfo($base, PATHINFO_EXTENSION));
            if (!in_array($ext, $imageExts, true)) {
                continue; // never touch .md or non-image files
            }
            if (isset($keepSet[$base])) {
                continue; // still in the arranged set — keep it
            }
            @unlink($path);
            if (is_file($path . '.meta.yaml')) {
                @unlink($path . '.meta.yaml');
            }
        }
    }

    /**
     * Rename the files named in $names to photo-1..N in that order, in $dir.
     * Two-phase via temp names so a target (photo-2.jpg) can't clobber a
     * not-yet-moved source of the same name.
     */
    private function renumberPhotos(string $dir, array $names): void
    {
        $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;
    }
}