<?php

declare(strict_types=1);

if (!defined('ABSPATH')) {
    exit;
}

/**
 * Local receiving gate for a future hosted AI advisor.
 *
 * This class deliberately has no HTTP client, provider settings, model name, or
 * credit accounting. It accepts a structured proposal only after another layer
 * has obtained one, then keeps WordPress as the local review/apply authority.
 */
final class TheDotDevAgenticBridge_AI_Proposal_Gate
{
    private const MAX_ID = 160;

    /** @param array<string, mixed> $proposal @return array{ok: bool, error: string, proposal?: array<string, mixed>} */
    public static function stage(array $proposal): array
    {
        if (self::pending() !== null) {
            return ['ok' => false, 'error' => 'pending_proposal_exists'];
        }
        foreach (['id', 'organizationId', 'siteId', 'contentId', 'fieldKey', 'beforeValue', 'proposedValue', 'beforeFingerprint', 'evidence'] as $key) {
            if (!array_key_exists($key, $proposal)) {
                return ['ok' => false, 'error' => 'invalid_proposal'];
            }
        }
        $settings = TheDotDevAgenticBridge_Storage::get();
        $organization_id = trim((string) ($settings['organization_id'] ?? ''));
        $site_id = trim((string) ($settings['site_id'] ?? ''));
        if ($organization_id === '' || $site_id === '' || !self::bounded($proposal['id'])) {
            return ['ok' => false, 'error' => 'invalid_proposal'];
        }
        if (!hash_equals($organization_id, (string) $proposal['organizationId'])) {
            return ['ok' => false, 'error' => 'organization_mismatch'];
        }
        if (!hash_equals($site_id, (string) $proposal['siteId'])) {
            return ['ok' => false, 'error' => 'site_mismatch'];
        }
        if (!hash_equals('agentSummary', (string) $proposal['fieldKey'])) {
            return ['ok' => false, 'error' => 'field_not_allowed'];
        }
        $content_id = is_int($proposal['contentId']) ? $proposal['contentId'] : 0;
        $post = get_post($content_id);
        if ($content_id <= 0 || !$post instanceof WP_Post || !TheDotDevAgenticBridge_Content_Metadata::is_configurable_content($post)) {
            return ['ok' => false, 'error' => 'content_not_configurable'];
        }
        $before = self::summary($content_id);
        $fingerprint = self::fingerprint($content_id, (string) get_permalink($post), $before);
        if (!hash_equals($before, (string) $proposal['beforeValue']) || !self::valid_fingerprint((string) $proposal['beforeFingerprint']) || !hash_equals($fingerprint, (string) $proposal['beforeFingerprint'])) {
            return ['ok' => false, 'error' => 'content_conflict'];
        }
        $proposed = trim((string) $proposal['proposedValue']);
        if ($proposed === '' || strlen($proposed) > TheDotDevAgenticBridge_Content_Metadata::MAX_SUMMARY_CHARS || TheDotDevAgenticBridge_Content_Metadata::contains_dangerous_text_public($proposed)) {
            return ['ok' => false, 'error' => 'unsafe_proposed_value'];
        }
        $record = [
            'id' => (string) $proposal['id'], 'organizationId' => $organization_id, 'siteId' => $site_id,
            'contentId' => $content_id, 'fieldKey' => 'agentSummary', 'beforeValue' => $before,
            'proposedValue' => $proposed, 'beforeFingerprint' => $fingerprint,
            'evidence' => sanitize_text_field((string) $proposal['evidence']),
            'state' => 'staged', 'stagedAt' => gmdate('c'),
        ];
        TheDotDevAgenticBridge_Storage::update(['ai_proposal_pending' => $record]);
        return ['ok' => true, 'error' => '', 'proposal' => $record];
    }

    /** @return array{ok: bool, error: string} */
    public static function approve(string $id, int $actor_id): array
    {
        $record = self::pending();
        if (!is_array($record) || !hash_equals((string) ($record['id'] ?? ''), $id) || $actor_id <= 0) {
            return ['ok' => false, 'error' => 'proposal_mismatch'];
        }
        if (($record['state'] ?? '') !== 'staged') {
            return ['ok' => false, 'error' => 'approval_not_available'];
        }
        $record['state'] = 'approved'; $record['approvedBy'] = $actor_id; $record['approvedAt'] = gmdate('c');
        TheDotDevAgenticBridge_Storage::update(['ai_proposal_pending' => $record]);
        return ['ok' => true, 'error' => ''];
    }

    /** @return array{ok: bool, error: string, auditId?: string} */
    public static function apply(string $id, int $actor_id): array
    {
        $record = self::pending();
        if (!is_array($record) || !hash_equals((string) ($record['id'] ?? ''), $id) || $actor_id <= 0 || ($record['state'] ?? '') !== 'approved') {
            return ['ok' => false, 'error' => 'approval_required'];
        }
        $content_id = (int) ($record['contentId'] ?? 0); $post = get_post($content_id);
        $before = self::summary($content_id);
        $current = $post instanceof WP_Post ? self::fingerprint($content_id, (string) get_permalink($post), $before) : '';
        if (!$post instanceof WP_Post || !hash_equals((string) ($record['beforeValue'] ?? ''), $before) || !hash_equals((string) ($record['beforeFingerprint'] ?? ''), $current)) {
            return ['ok' => false, 'error' => 'content_conflict'];
        }
        $snapshot = TheDotDevAgenticBridge_Content_Metadata::raw_record($content_id);
        $config = TheDotDevAgenticBridge_Content_Metadata::effective_config_for_post($post);
        $config['agentSummary'] = (string) $record['proposedValue'];
        $result = TheDotDevAgenticBridge_Content_Metadata::save_content_config($content_id, $config);
        if (empty($result['ok']) || !hash_equals((string) $record['proposedValue'], self::summary($content_id))) {
            return ['ok' => false, 'error' => 'apply_verification_failed'];
        }
        $audit_id = function_exists('wp_generate_uuid4') ? wp_generate_uuid4() : ('ai-proposal-' . gmdate('YmdHis'));
        $audit = self::audit();
        $audit[] = ['id' => $audit_id, 'proposalId' => $id, 'contentId' => $content_id, 'beforeValue' => $before, 'appliedValue' => (string) $record['proposedValue'], 'rawSnapshot' => $snapshot, 'appliedAt' => gmdate('c'), 'appliedBy' => $actor_id, 'undoneAt' => ''];
        TheDotDevAgenticBridge_Storage::update(['ai_proposal_pending' => null, 'ai_proposal_audit' => $audit]);
        return ['ok' => true, 'error' => '', 'auditId' => $audit_id];
    }

    /** @return array{ok: bool, error: string} */
    public static function undo(string $audit_id, int $actor_id): array
    {
        $audit = self::audit();
        foreach ($audit as $index => $entry) {
            if (!is_array($entry) || !hash_equals((string) ($entry['id'] ?? ''), $audit_id)) { continue; }
            if ($actor_id <= 0 || !empty($entry['undoneAt'])) { return ['ok' => false, 'error' => 'undo_not_available']; }
            $content_id = (int) ($entry['contentId'] ?? 0);
            if (!hash_equals((string) ($entry['appliedValue'] ?? ''), self::summary($content_id))) { return ['ok' => false, 'error' => 'restore_refused']; }
            $result = TheDotDevAgenticBridge_Content_Metadata::restore_raw_record($content_id, is_array($entry['rawSnapshot'] ?? null) ? $entry['rawSnapshot'] : []);
            if (empty($result['ok']) || !hash_equals((string) $entry['beforeValue'], self::summary($content_id))) { return ['ok' => false, 'error' => 'restore_verification_failed']; }
            $audit[$index]['undoneAt'] = gmdate('c'); TheDotDevAgenticBridge_Storage::update(['ai_proposal_audit' => $audit]);
            return ['ok' => true, 'error' => ''];
        }
        return ['ok' => false, 'error' => 'audit_not_found'];
    }

    /** @return array<string, mixed>|null */
    public static function pending(): ?array { $value = TheDotDevAgenticBridge_Storage::get()['ai_proposal_pending'] ?? null; return is_array($value) ? $value : null; }
    /** @return list<array<string, mixed>> */
    public static function audit(): array { $value = TheDotDevAgenticBridge_Storage::get()['ai_proposal_audit'] ?? []; return is_array($value) ? $value : []; }
    public static function fingerprint(int $content_id, string $url, string $value): string { return hash('sha256', wp_json_encode(['contentId' => $content_id, 'url' => $url, 'value' => $value], JSON_UNESCAPED_SLASHES) ?: ''); }
    private static function summary(int $content_id): string { $store = TheDotDevAgenticBridge_Content_Metadata::normalized_store(); return (string) ($store['by_content_id'][(string) $content_id]['agentSummary'] ?? ''); }
    private static function bounded(mixed $value): bool { return is_string($value) && trim($value) !== '' && strlen($value) <= self::MAX_ID; }
    private static function valid_fingerprint(string $value): bool { return (bool) preg_match('/^[a-f0-9]{64}$/', $value); }
}