<?php

declare(strict_types=1);

namespace LIT\MCP\Integrations\Divi\Design;

use LIT\MCP\Integrations\Divi\BlockTree\Block;
use LIT\MCP\Integrations\Divi\Compose\VariableRef;

defined('ABSPATH') || exit;

/**
 * Replaces the references to global variable $id in the attributes of Divi blocks by its value (lit/divi-design-detach
 * with variable, ruling V9): every attribute value that is exactly one reference $variable({"type":"content",
 * "value":{"name":"<id>",…}})$ becomes the value – for a strings variable with the reference's own before/after
 * around it. References embedded in a longer text stay (Divi resolves them inside the text; cutting them out would
 * change the text) and are reported through leftover() (ReportsLeftovers). Other references – colors, other
 * variables, dynamic content – stay untouched. Pure PHP.
 */
final class VariableDetachRewrite implements NodeRewrite, ReportsLeftovers
{
    private const EMBEDDED = 'Die Variable steht hier eingebettet in einem längeren Text; dieser Verweis bleibt '
        . 'unverändert – im Divi-Builder prüfen.';

    private const UNSAFE = 'Vor- oder Nachtext des Verweises enthält Markup oder einen Verweis; der Verweis bleibt '
        . 'unverändert – im Divi-Builder prüfen.';

    /** @param bool $markupAllowed Whether "<" and ">" may enter the content (unfiltered_html); markers never may. */
    public function __construct(
        private string $id,
        private string $value,
        private string $variableType,
        private bool $markupAllowed = false
    ) {
    }

    /**
     * Whether $text must not be inlined into content: it holds a reference marker (it never went through
     * VariableRef::canonical()) or – without unfiltered_html – markup (D7, S1).
     */
    public static function unsafe(string $text, bool $markupAllowed): bool
    {
        return str_contains($text, VariableRef::MARKER) || str_contains($text, VariableRef::END)
            || (! $markupAllowed && (str_contains($text, '<') || str_contains($text, '>')));
    }

    /**
     * What one whole reference to a variable of $variableType becomes: its value, for strings with the reference's
     * before/after settings around it.
     */
    public static function replacement(string $reference, string $value, string $variableType): string
    {
        if ($variableType !== 'strings') {
            return $value;
        }
        $settings = VariableRef::settingsOf($reference);
        $before = is_string($settings['before'] ?? null) ? $settings['before'] : '';
        $after = is_string($settings['after'] ?? null) ? $settings['after'] : '';

        return $before . $value . $after;
    }

    public function rewrite(Block $block): ?array
    {
        if (! $block->isDivi() || $this->hasUnsafeAffix($block->attrs())) {
            return null; // fail closed: the block stays whole and leftover() reports it
        }

        $changed = false;
        $attrs = $this->resolved($block->attrs(), $changed);

        return $changed && is_array($attrs) ? $attrs : null;
    }

    public function notes(Block $block, string $nodeId): array
    {
        return []; // leftovers go through leftover(): they also matter for blocks rewrite() did not change
    }

    public function leftover(Block $block): ?string
    {
        if (! $block->isDivi()) {
            return null;
        }
        if ($this->hasUnsafeAffix($block->attrs())) {
            return self::UNSAFE;
        }

        return $this->embeds($block->attrs()) ? self::EMBEDDED : null;
    }

    public function concernsInstance(Block $instance): bool
    {
        return DetachRewrite::mentions($instance, $this->id);
    }

    /** $value with every whole reference to the variable replaced; $changed tells whether one was. */
    private function resolved(mixed $value, bool &$changed): mixed
    {
        if (is_string($value)) {
            if (VariableRef::nameOf($value) !== $this->id) {
                return $value;
            }
            $changed = true;

            return self::replacement($value, $this->value, $this->variableType);
        }
        if (! is_array($value)) {
            return $value;
        }

        foreach ($value as $key => $item) {
            $value[$key] = $this->resolved($item, $changed);
        }

        return $value;
    }

    /** Whether a whole reference below $value carries before/after text that must not be inlined. */
    private function hasUnsafeAffix(mixed $value): bool
    {
        if (is_string($value)) {
            if ($this->variableType !== 'strings' || VariableRef::nameOf($value) !== $this->id) {
                return false;
            }
            $settings = VariableRef::settingsOf($value);

            foreach (['before', 'after'] as $key) {
                $text = is_string($settings[$key] ?? null) ? $settings[$key] : '';
                if (self::unsafe($text, $this->markupAllowed)) {
                    return true;
                }
            }

            return false;
        }
        if (! is_array($value)) {
            return false;
        }
        foreach ($value as $item) {
            if ($this->hasUnsafeAffix($item)) {
                return true;
            }
        }

        return false;
    }

    /** Whether a string below $value names the variable inside a longer text. */
    private function embeds(mixed $value): bool
    {
        if (is_string($value)) {
            return VariableRef::contains($value) && str_contains($value, '"' . $this->id . '"');
        }
        if (! is_array($value)) {
            return false;
        }

        foreach ($value as $item) {
            if ($this->embeds($item)) {
                return true;
            }
        }

        return false;
    }
}