<?php

declare(strict_types=1);

namespace LIT\MCP\Integrations\Divi\Pages;

use LIT\MCP\Abilities\Errors;
use LIT\MCP\Abilities\Rev;
use LIT\MCP\Abilities\ToolResult;
use LIT\MCP\Abilities\WriteFailed;
use LIT\MCP\ChangeLog\ChangeLog;
use LIT\MCP\Integrations\Divi\BlockTree\NodeIndex;
use LIT\MCP\Integrations\Divi\BlockTree\Outline;
use LIT\MCP\Integrations\Divi\BlockTree\Serializer;
use LIT\MCP\Integrations\Divi\Design\DesignSystemReader;
use LIT\MCP\Integrations\Divi\Library\GlobalEdits;
use LIT\MCP\Integrations\Divi\Library\SimilarSections;
use LIT\MCP\Integrations\Divi\ThemeBuilder\ThemeBuilderEdits;
use LIT\MCP\Integrations\WordPress\PostSaveFollowUp;
use WP_Error;

defined('ABSPATH') || exit;

/**
 * The shared frame of every Divi write (spec §5.6): load with rights and the tree_rev lock
 * (ruling P16; a mismatch is rev_mismatch and nothing is written), let the ability change the
 * tree – only when its whole input validated (all or nothing) –, serialize, save via DiviSaver,
 * then lit_mcp_after_save, change log and the ToolResult with changed nodes, affected outline,
 * quality warnings (spec §5.5), revision_id, the new rev and tree_rev. commit() is the entry point
 * of the tools: library entries additionally pass GlobalEdits (shape, dry run/confirm, backup), Theme
 * Builder layouts ThemeBuilderEdits (live layouts: dry run/confirm, backup; ruling Q2/Q9). SimilarSections adds
 * the "similar section" warning (spec §5.5, E11) – not for lit/library-insert, whose sections come from the library.
 */
final class DiviWriter
{
    public const OUTLINE_TRUNCATED = 'Die Übersicht der geänderten Abschnitte ist gekürzt; vollständig mit '
        . 'lit-divi-outline lesen.';

    /** Inserts library entries: no advice to use the library (SimilarSections). */
    private const FROM_LIBRARY = 'lit/library-insert';

    public function __construct(
        private DiviPageLoader $loader,
        private DiviSaver $saver,
        private ChangeLog $log,
        private DesignSystemReader $design,
        private DiviComposition $composition,
        private ?GlobalEdits $globals = null,
        private ?ThemeBuilderEdits $themeBuilder = null,
        private ?SimilarSections $similar = null
    ) {
    }

    /**
     * The page to change, after rights, type, layout and the tree_rev lock were checked.
     *
     * @param array<string, mixed> $input
     */
    public function page(array $input): DiviPage|WP_Error
    {
        $page = $this->loader->loadWritable($input['post_id'] ?? null);
        if ($page instanceof WP_Error) {
            return $page;
        }

        if (! is_string($input['tree_rev'] ?? null) || $input['tree_rev'] !== $page->treeRev()) {
            return Errors::revMismatch(
                'Die Divi-Seite wurde seit dem letzten Lesen geändert (tree_rev passt nicht); nichts wurde '
                    . 'geschrieben.',
                DiviPageLoader::OUTLINE_HINT
            );
        }

        return $page;
    }

    /**
     * The Compose classes for $page: bound to its entry, so placeholders and $variable(…)$
     * references are checked against Divi's dynamic content options for it (ruling S22); a Theme
     * Builder layout also by its area (F22: modules Divi renders only elsewhere are refused).
     */
    public function composition(DiviPage $page): DiviComposition
    {
        return $this->composition->forPost((int) $page->post->ID, $page->themeBuilderArea());
    }

    /**
     * Saves the changed tree of $page and returns the ToolResult array. Call it only when the
     * whole input validated – every error before means nothing is written.
     *
     * @param array<string, mixed> $input
     * @return array<string, mixed>
     * @throws WriteFailed
     */
    public function save(
        string $ability,
        DiviPage $page,
        DiviChange $change,
        array $input,
        SaveScope $scope = SaveScope::Page
    ): array {
        $post = $page->post;
        $content = Serializer::document($page->document);
        if ($content === (string) $post->post_content) {
            return ToolResult::ok('Keine Änderung – die Seite ist bereits so.')
                ->rev(Rev::ofPost($post))
                ->with('tree_rev', $page->treeRev())
                ->warnings($change->warnings())
                ->urls((string) get_preview_post_link($post), $page->editUrl())
                ->toArray();
        }

        $index = NodeIndex::build($page->document);
        $quality = $this->composition->warnings()->collect($index, $change->touched());
        $similar = $ability === self::FROM_LIBRARY ? [] : ($this->similar?->warnings($change) ?? []);
        $warnings = array_merge($change->warnings(), $quality, $similar);

        try {
            $saved = $this->saver->save($post, $content, $scope);
        } catch (WriteFailed $e) {
            if (! $e->rolledBack) {
                $this->log->recordPartial(
                    $ability,
                    (string) $post->post_type,
                    (string) $post->ID,
                    sprintf('Divi "%s": Änderung nur teilweise zurückgenommen', $post->post_title),
                    $e->revisionId
                );
            }
            throw $e;
        }

        $outline = $this->outline($index, $change);
        if ($outline['truncated']) {
            $warnings[] = self::OUTLINE_TRUNCATED;
        }

        $result = (new PostSaveFollowUp(
            $ability,
            $this->log,
            (int) $post->ID,
            'die Änderung',
            array_merge($warnings, $saved['warnings'])
        ))->afterSave($input);
        $updated = $result->reread($post) ?? $post;
        $summary = sprintf('Divi "%s": %s', $post->post_title, $change->summary);
        $result->log((string) $post->post_type, $summary, $saved['revision_id']);

        $status = sprintf('%s (Status unverändert: %s).', $change->summary, $updated->post_status);
        $tool = $result->result($status, $updated)
            ->revisionId($saved['revision_id'])
            ->outline($outline['text'])
            ->with('tree_rev', Rev::of((string) $updated->post_content))
            ->urls((string) get_preview_post_link($updated), $page->editUrl());
        foreach ($change->entries() as $entry) {
            $tool->changed(DiviChange::idOf($entry, $index) ?? '?', $entry['type'], $entry['action'], $entry['label']);
        }
        $restore = self::restoreUrl($page, $saved['revision_id']);
        if ($restore !== null) {
            $tool->with('restore_url', $restore);
        }

        return $tool->toArray();
    }

    /**
     * Audit L3: lit/revision-restore takes only the content types (ContentSchema) – not library entries or Theme
     * Builder layouts. Their revision is restored in WordPress' revision screen; null for everything else.
     */
    private static function restoreUrl(DiviPage $page, mixed $revisionId): ?string
    {
        $noRestoreTool = $page->isLibraryItem() || $page->isThemeBuilderLayout();
        if (! $noRestoreTool || ! is_int($revisionId) || $revisionId <= 0) {
            return null;
        }

        return admin_url('revision.php?revision=' . $revisionId);
    }

    /**
     * save() for the Divi tools (E2): pages as before; a library entry keeps its shape, a global one
     * needs confirm (dry run first), gets a backup when revisions are off and clears every page's
     * cache; the result then names the affected pages. Theme Builder layouts: commitLayout().
     *
     * @param array<string, mixed> $input
     * @return array<string, mixed>|WP_Error
     * @throws WriteFailed
     */
    public function commit(string $ability, DiviPage $page, DiviChange $change, array $input): array|WP_Error
    {
        if ($page->isThemeBuilderLayout()) {
            return $this->commitLayout($ability, $page, $change, $input);
        }

        if (! $page->isLibraryItem()) {
            return $this->save($ability, $page, $change, $input);
        }

        if ($this->globals === null) {
            return Errors::unsupported(
                'Bibliothekseinträge lassen sich über diese Verbindung nicht ändern.',
                'Den Eintrag im Divi-Builder bearbeiten.'
            );
        }

        if (Serializer::document($page->document) === (string) $page->post->post_content) {
            return $this->save($ability, $page, $change, $input, SaveScope::LibraryItem);
        }

        $prepared = $this->globals->prepare($page, $input);
        if ($prepared instanceof WP_Error) {
            return $prepared;
        }

        return $this->savePrepared($ability, $page, $change, $input, $prepared, 'des Bibliothekseintrags');
    }

    /**
     * save() for a Theme Builder layout: a layout visitors see needs confirm and gets the restore point
     * of a visible change (ThemeBuilderEdits, rulings Q2/Q9); the result names the templates that show it.
     *
     * @param array<string, mixed> $input
     * @return array<string, mixed>|WP_Error
     * @throws WriteFailed
     */
    private function commitLayout(string $ability, DiviPage $page, DiviChange $change, array $input): array|WP_Error
    {
        if ($this->themeBuilder === null) {
            return Errors::unsupported(
                'Theme-Builder-Layouts lassen sich über diese Verbindung nicht ändern.',
                'Das Layout im Divi Theme Builder bearbeiten.'
            );
        }

        if (Serializer::document($page->document) === (string) $page->post->post_content) {
            return $this->save($ability, $page, $change, $input, SaveScope::ThemeBuilderLayout);
        }

        // E12: fields in a body checked against the templates' post types – warnings only, also in the dry run
        // and in any refusal (review M-12 a). The live templates are read once for both checks.
        $live = $this->themeBuilder->live();
        $fieldWarnings = $this->themeBuilder->fieldWarnings($page, $change, $live);
        foreach ($fieldWarnings as $warning) {
            $change->warning($warning);
        }

        $prepared = $this->themeBuilder->prepare($page, $input, $live);
        if ($prepared instanceof WP_Error) {
            return $fieldWarnings === [] ? $prepared : self::withWarnings($prepared, $fieldWarnings);
        }

        return $this->savePrepared($ability, $page, $change, $input, $prepared, 'des Theme-Builder-Layouts');
    }

    /**
     * $error with the field warnings of the change (key warnings): a confirm_required also says so in its message.
     *
     * @param list<string> $warnings
     */
    private static function withWarnings(WP_Error $error, array $warnings): WP_Error
    {
        if (Errors::codeOf($error) === 'confirm_required') {
            return VisibleEdits::merged($error, 'Hinweise zu Feldern siehe warnings.', ['warnings' => $warnings]);
        }

        $data = $error->get_error_data();
        $data = is_array($data) ? $data : [];

        return Errors::make(
            Errors::codeOf($error),
            Errors::clientMessage($error),
            (string) ($data['hint'] ?? ''),
            (int) ($data['status'] ?? 400),
            array_merge(array_diff_key($data, ['status' => true, 'hint' => true]), ['warnings' => $warnings])
        );
    }

    /**
     * save() with the scope GlobalEdits/ThemeBuilderEdits prepared; their details join the result, and a
     * failure after their backup names it (ruling P14, VisibleEdits). $entry names the entry in that error.
     *
     * @param array<string, mixed> $input
     * @param array{scope: SaveScope, details: array<string, mixed>} $prepared
     * @return array<string, mixed>
     * @throws WriteFailed
     */
    private function savePrepared(
        string $ability,
        DiviPage $page,
        DiviChange $change,
        array $input,
        array $prepared,
        string $entry
    ): array {
        try {
            $saved = $this->save($ability, $page, $change, $input, $prepared['scope']);
        } catch (WriteFailed $e) {
            throw VisibleEdits::keepingBackup($e, $prepared['details']['backup_id'] ?? null, $entry);
        }

        return array_merge($saved, $prepared['details']);
    }

    /** A tool's confirm_required on a global library entry or a live Theme Builder layout, extended by who sees it. */
    public function notice(DiviPage $page, WP_Error $error): WP_Error
    {
        if ($page->isThemeBuilderLayout()) {
            return $this->themeBuilder?->notice($page, $error) ?? $error;
        }

        return $page->isLibraryItem() && $this->globals !== null ? $this->globals->notice($page, $error) : $error;
    }

    /**
     * Outline of the sections that contain changed nodes (breadth limit of ruling S18). A removed
     * node has no block any more, but its ID from before the removal still names the (surviving)
     * section – unless the removed node was that section itself: its ID now names the next section,
     * which did not change (review m-7).
     *
     * @return array{text: ?string, truncated: bool}
     */
    private function outline(NodeIndex $index, DiviChange $change): array
    {
        $sections = [];
        foreach ($change->entries() as $entry) {
            $id = DiviChange::idOf($entry, $index);
            $wholeSection = $entry['block'] === null && $id !== null && ! str_contains($id, '.');
            if ($id !== null && ! $wholeSection) {
                $sections[explode('.', $id)[0]] = true;
            }
        }

        if ($sections === []) {
            return ['text' => null, 'truncated' => false];
        }

        $outline = new Outline($this->design->read()->presetNames(), $this->loader->libraryIdsVisible());

        return $outline->summary($index, array_map('strval', array_keys($sections)));
    }
}