<?php

declare(strict_types=1);

/**
 * SPDX-FileCopyrightText: Sebastian Krupinski <krupinski01@gmail.com>
 * SPDX-License-Identifier: AGPL-3.0-or-later
 */

namespace KTXM\ProviderImap\Providers;

use DateTimeImmutable;
use DateTimeInterface;
use KTXM\ProviderImap\Client\Message;
use KTXM\ProviderImap\Client\MessagePart as ClientMessagePart;
use KTXF\Mail\Object\MessagePropertiesMutableAbstract;

/**
 * Mail Message Properties Implementation
 */
class MessageProperties extends MessagePropertiesMutableAbstract {

    /**
     * Part ids of text sections that were cut off when fetched (cache only, not part of the API shape)
     *
     * @var list<string>
     */
    private array $incompleteSections = [];

    /**
     * Convert IMAP data to mail message properties object.
     */
    public function fromImap(Message $message): static
    {
        $this->data[static::PROPERTY_SIZE] = $message->size();
        $this->incompleteSections = $message->truncatedSections();

        if ($message->messageId() !== null) {
            $this->data[static::PROPERTY_URID] = $message->messageId();
        }

        if ($message->inReplyTo() !== null) {
            $this->data[static::PROPERTY_IN_REPLY_TO] = $message->inReplyTo();
        }

        if ($message->references() !== []) {
            $this->data[static::PROPERTY_REFERENCES] = $message->references();
        }

        $receivedAt = $message->receivedAt() ?? $message->internalDate();
        if ($receivedAt !== null) {
            $date = new DateTimeImmutable($receivedAt);
            $this->data[static::PROPERTY_RECEIVED] = $date->format(DateTimeInterface::ATOM);
        }

        if ($message->sentAt() !== null) {
            $date = new DateTimeImmutable($message->sentAt());
            $this->data[static::PROPERTY_SENT] = $date->format(DateTimeInterface::ATOM);
        }

        if ($message->sender() !== []) {
            $this->data[static::PROPERTY_SENDER] = $message->sender()[0]->toArray();
        }

        if ($message->from() !== []) {
            $this->data[static::PROPERTY_FROM] = $message->from()[0]->toArray();
        }

        $addressProperties = [
            'to' => static::PROPERTY_TO,
            'cc' => static::PROPERTY_CC,
            'bcc' => static::PROPERTY_BCC,
            'replyTo' => static::PROPERTY_REPLY_TO,
        ];

        foreach ($addressProperties as $field => $property) {
            $addresses = $message->{$field}();
            if ($addresses === []) {
                continue;
            }

            $this->data[$property] = array_map(
                static fn ($address): array => $address->toArray(),
                $addresses,
            );
        }

        if ($message->subject() !== null) {
            $this->data[static::PROPERTY_SUBJECT] = $message->subject();
        }

        if ($message->bodyStructure() !== null) {
            $body = $message->bodyStructure()->withInjectedSections($message->bodySections() ?? [])->toArray();
            $this->data[static::PROPERTY_BODY] = $body;

            $attachments = [];
            $this->collectAttachments($body, $attachments);
            if ($attachments !== []) {
                $this->data[static::PROPERTY_ATTACHMENTS] = $attachments;
            }
        }

        $this->data[static::PROPERTY_FLAGS] = array_fill_keys(self::normalizeFlags($message->flags()), true);

        return $this;
    }

    /**
     * Normalise IMAP flags (e.g. "\\Seen", "$Forwarded") to flag names (e.g. "seen", "$forwarded").
     *
     * @param string[] $flags
     * @return list<string>
     */
    public static function normalizeFlags(array $flags): array
    {
        $normalized = [];
        foreach ($flags as $flag) {
            $normalized[] = strtolower(ltrim($flag, '\\'));
        }

        return array_values(array_unique($normalized));
    }

    // ── Cache (meta store / content store) ───────────────────────────────────

    /**
     * Part ids of text sections that were cut off when fetched and must be completed on open.
     *
     * @return list<string>
     */
    public function getIncompleteSections(): array
    {
        return $this->incompleteSections;
    }

    public function setIncompleteSections(string ...$partIds): static
    {
        $this->incompleteSections = array_values(array_unique($partIds));
        return $this;
    }

    /**
     * Serialise the fields the meta store needs for list, filter and sort.
     *
     * Dates are normalised to UTC so they sort correctly as strings; the original
     * values (with their offsets) are kept in the content store.
     */
    public function toCacheMeta(): array
    {
        return [
            'received'       => self::cacheDate($this->data[static::PROPERTY_RECEIVED] ?? null),
            'sent'           => self::cacheDate($this->data[static::PROPERTY_SENT] ?? null),
            'size'           => $this->data[static::PROPERTY_SIZE] ?? 0,
            'subject'        => $this->data[static::PROPERTY_SUBJECT] ?? '',
            'from'           => $this->data[static::PROPERTY_FROM] ?? null,
            'to'             => $this->data[static::PROPERTY_TO] ?? [],
            'cc'             => $this->data[static::PROPERTY_CC] ?? [],
            'urid'           => $this->data[static::PROPERTY_URID] ?? null,
            'inReplyTo'      => $this->data[static::PROPERTY_IN_REPLY_TO] ?? null,
            'references'     => $this->data[static::PROPERTY_REFERENCES] ?? [],
            // list of set flags, not a map: keywords such as $Forwarded are not valid field names
            'flags'          => array_keys(array_filter($this->data[static::PROPERTY_FLAGS] ?? [])),
            'hasAttachments' => ($this->data[static::PROPERTY_ATTACHMENTS] ?? []) !== [],
            'preview'        => $this->cachePreview(),
        ];
    }

    /**
     * Restore the mutable fields from a meta store document.
     *
     * Only flags are taken from the meta store; everything else comes from the
     * content store, which holds the original values.
     */
    public function fromCacheMeta(array $document): static
    {
        $this->data[static::PROPERTY_FLAGS] = array_fill_keys(
            array_map('strval', (array) ($document['flags'] ?? [])),
            true,
        );

        return $this;
    }

    /**
     * Serialise the immutable message content for the content store.
     */
    public function toCacheContent(): array
    {
        $content = $this->data;
        unset($content[static::PROPERTY_FLAGS]);

        return $content;
    }

    /**
     * Restore the immutable message content from the content store, keeping any flags already set.
     */
    public function fromCacheContent(array $content): static
    {
        unset($content[static::PROPERTY_FLAGS]);
        $flags = $this->data[static::PROPERTY_FLAGS] ?? null;

        $this->data = $content;
        if ($flags !== null) {
            $this->data[static::PROPERTY_FLAGS] = $flags;
        }

        return $this;
    }

    private function cachePreview(int $length = 200): string
    {
        $text = $this->getBodyTextPlain();
        if ($text === null) {
            $html = $this->getBodyTextHtml();
            $text = $html !== null
                ? html_entity_decode(strip_tags((string) preg_replace('/<(style|script)\b[^>]*>.*?<\/\1>/is', ' ', $html)), ENT_QUOTES | ENT_HTML5, 'UTF-8')
                : '';
        }

        $text = trim((string) preg_replace('/\s+/u', ' ', $text));

        return mb_substr($text, 0, $length);
    }

    private static function cacheDate(?string $value): ?string
    {
        if ($value === null || $value === '') {
            return null;
        }

        try {
            return (new DateTimeImmutable($value))
                ->setTimezone(new \DateTimeZone('UTC'))
                ->format('Y-m-d\TH:i:s\Z');
        } catch (\Exception) {
            return null;
        }
    }

    /**
     * Recursively collect attachment parts from body structure
     */
    private function collectAttachments(array $part, array &$attachments): void
    {
        $children = $part['subParts'] ?? [];
        if ($children !== []) {
            foreach ($children as $childPart) {
                $this->collectAttachments($childPart, $attachments);
            }
            return;
        }

        $mimeType = strtolower((string)($part['type'] ?? ''));
        $disposition = strtolower((string)($part['disposition'] ?? ''));
        $name = $part['name'] ?? null;
        $isInlineText = str_starts_with($mimeType, 'text/')
            && in_array($mimeType, ['text/plain', 'text/html'], true)
            && $disposition !== 'attachment';

        if ($isInlineText || ($disposition === '' && $name === null)) {
            return;
        }

        $attachments[] = $part;
    }

}