<?php

declare(strict_types=1);

namespace Sarcio\WordPress\Assistant;

final class JournalAbilities
{
    /** @return array<int,Ability> */
    public static function abilities(): array
    {
        return [
            new Ability(
                'sarcio/changes-list',
                __('Look at recent changes', 'sarcio'),
                Ability::READ,
                'The last changes the assistant made on this site (id, when, what, whether it was undone), newest first. Use changes-undo with an id to put one back.',
                ['properties' => ['limit' => ['maximum' => 50, 'minimum' => 1, 'type' => 'integer']], 'required' => [], 'type' => 'object'],
                static fn (array $args): bool => current_user_can('edit_posts'),
                static fn (array $args): array => ['changes' => self::list((int) ($args['limit'] ?? 50))],
            ),
            new Ability(
                'sarcio/changes-undo',
                __('Undo a change', 'sarcio'),
                Ability::WRITE,
                'Undo one of the assistant’s earlier changes by its id from changes-list. Installing a plugin cannot be undone; everything else can.',
                ['properties' => ['id' => ['minimum' => 1, 'type' => 'integer']], 'required' => ['id'], 'type' => 'object'],
                static fn (array $args): bool => current_user_can('edit_posts'),
                static fn (array $args): array => self::undo((int) $args['id']),
                static fn (array $args): array => self::undoPreview((int) $args['id']),
            ),
        ];
    }

    /** @return array<int,array<string,mixed>> */
    public static function list(int $limit = 50): array
    {
        $out = [];
        foreach (Journal::recent() as $entry) {
            if (count($out) >= $limit) {
                break;
            }
            if (!self::visible($entry)) {
                continue;
            }
            $ability = Catalog::get($entry['ability']);
            [$before, $after] = self::changedText($entry['before'], $entry['after']);
            $out[] = [
                'after' => $after,
                'at' => $entry['createdAt'],
                'before' => $before,
                'by' => self::userName($entry['userId']),
                'id' => $entry['id'],
                'label' => $ability?->label ?? $entry['ability'],
                'summary' => $entry['summary'],
                'note' => $entry['undoneAt'] === null ? Catalog::inactiveReason($entry['ability']) : null,
                'undoable' => $entry['undoneAt'] === null && $ability !== null && $ability->undo !== null,
                'undoneAt' => $entry['undoneAt'],
            ];
        }
        return $out;
    }

    /**
     * The fields a change touched, one `name: value` line each, as text the
     * screen can diff. Values that are not text are shown as JSON.
     *
     * @param array<string,mixed> $before
     * @param array<string,mixed> $after
     * @return array{0:string,1:string}
     */
    private static function changedText(array $before, array $after): array
    {
        $keys = array_unique(array_merge(array_keys($before), array_keys($after)));
        $changed = array_values(array_filter($keys, static fn ($key) => ($before[$key] ?? null) !== ($after[$key] ?? null)));
        $line = static function (array $fields, string $key) use ($changed): string {
            $value = $fields[$key] ?? '';
            if ($key === 'builderData' && is_array($value)) {
                return Builders::textOf($value);
            }
            $text = is_scalar($value) || $value === null ? (string) $value : (string) wp_json_encode($value, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
            if (in_array($key, ['content', 'description', 'shortDescription', 'excerpt'], true)) {
                $text = ContentAbilities::readable($text);
            }
            return count($changed) === 1 ? $text : $key . ': ' . $text;
        };
        $side = static function (array $fields) use ($changed, $line): string {
            $lines = [];
            foreach ($changed as $key) {
                if (array_key_exists($key, $fields)) {
                    $lines[] = $line($fields, $key);
                }
            }
            return mb_substr(implode("\n", $lines), 0, 20000);
        };
        return [$side($before), $side($after)];
    }

    private static function undo(int $id): array
    {
        $result = Catalog::undo($id);
        if (!$result['ok']) {
            return ['error' => (string) ($result['error'] ?? '')];
        }
        return $result['output'] ?? ['undone' => true];
    }

    private static function undoPreview(int $id): array
    {
        $entry = Journal::get($id);
        if ($entry === null) {
            return ['error' => __('That change is no longer in the list.', 'sarcio')];
        }
        if (!self::visible($entry)) {
            return ['error' => __('You do not have permission to undo that.', 'sarcio')];
        }
        if ($entry['undoneAt'] !== null) {
            return ['error' => __('That change was already undone.', 'sarcio')];
        }
        $ability = Catalog::get($entry['ability']);
        if ($ability === null || $ability->undo === null) {
            return ['error' => Catalog::inactiveReason($entry['ability']) ?? __('That change cannot be undone from here.', 'sarcio')];
        }
        return [
            'after' => '',
            'before' => $entry['summary'],
            'summary' => sprintf(
                /* translators: %s: what the change did. */
                __('Undo: %s', 'sarcio'),
                $entry['summary'],
            ),
        ];
    }

    /**
     * Whether the signed-in user may see a change: an administrator sees them
     * all, anyone else the changes they could have made themselves, and a
     * change by an ability no longer here only its author.
     *
     * @param array{ability:string,before:array<string,mixed>,after:array<string,mixed>,userId:int} $entry
     */
    public static function visible(array $entry): bool
    {
        if (current_user_can('manage_options')) {
            return true;
        }
        $ability = $entry['ability'] === 'sarcio/changes-undo' ? null : Catalog::get($entry['ability']);
        if ($ability === null) {
            return $entry['userId'] === get_current_user_id();
        }
        return $ability->allowed($entry['before'] + $entry['after']);
    }

    private static function userName(int $userId): string
    {
        $user = function_exists('get_userdata') ? get_userdata($userId) : null;
        return is_object($user) && isset($user->display_name) ? (string) $user->display_name : '';
    }
}