<?php
namespace Zadex\Forms\Integrations;

defined('ABSPATH') || exit;

use WP_Error;

/**
 * Mailchimp Marketing API v3. The datacenter comes from the API key suffix (`…-us21` →
 * `https://us21.api.mailchimp.com/3.0`), auth is HTTP Basic with the key as password.
 *
 *  - upsert: PUT /lists/{list}/members/{md5(lowercase email)} {email_address, status_if_new, merge_fields}
 *    (`status_if_new` = `pending` with double opt-in, else `subscribed`; FNAME / LNAME from the name fields,
 *    other merge tags from the `mailchimp_fields` mapping)
 *  - tags:   POST /lists/{list}/members/{hash}/tags {tags: [{name, status: active}]}
 *  - lists:  GET /lists?count=100&fields=lists.id,lists.name
 */
final class Mailchimp extends EmailProvider
{
    public function id(): string
    {
        return 'mailchimp';
    }

    public function label(): string
    {
        return 'Mailchimp';
    }

    public function configured(): bool
    {
        return $this->base() !== '';
    }

    public static function datacenter(string $key): string
    {
        $pos = strrpos($key, '-');
        $dc = $pos === false ? '' : strtolower(substr($key, $pos + 1));
        return preg_match('/^[a-z]{2,4}\d{1,3}$/', $dc) ? $dc : '';
    }

    public function base(): string
    {
        $dc = self::datacenter(Credentials::get('mailchimp_api_key'));
        return $dc !== '' ? 'https://' . $dc . '.api.mailchimp.com/3.0' : '';
    }

    /** @return array<string, string> */
    private function headers(): array
    {
        return ['Authorization' => self::basic('zadex', Credentials::get('mailchimp_api_key'))];
    }

    public function lists()
    {
        if (!$this->configured()) {
            return new WP_Error('zadex_integration_not_configured', 'Mailchimp API key missing or invalid.');
        }
        $r = Http::request('GET', $this->base() . '/lists?count=100&fields=lists.id,lists.name', ['headers' => $this->headers()]);
        return $r instanceof WP_Error ? $r : self::options($r['json']['lists'] ?? [], 'id', 'name');
    }

    public function subscribe(array $contact)
    {
        $list = rawurlencode($contact['list']);
        $hash = md5(strtolower($contact['email']));
        $merge = $contact['fields'];
        if ($contact['first_name'] !== '' && !isset($merge['FNAME'])) {
            $merge['FNAME'] = $contact['first_name'];
        }
        if ($contact['last_name'] !== '' && !isset($merge['LNAME'])) {
            $merge['LNAME'] = $contact['last_name'];
        }
        $body = [
            'email_address' => $contact['email'],
            'status_if_new' => $contact['double_optin'] ? 'pending' : 'subscribed',
        ];
        if ($merge) {
            $body['merge_fields'] = $merge;
        }
        $member = $this->base() . '/lists/' . $list . '/members/' . $hash;
        $r = Http::json('PUT', $member, $body, $this->headers());
        if ($r instanceof WP_Error) {
            return $r;
        }
        if ($contact['tags']) {
            $tags = array_map(static fn(string $t): array => ['name' => $t, 'status' => 'active'], $contact['tags']);
            $t = Http::json('POST', $member . '/tags', ['tags' => $tags], $this->headers());
            if ($t instanceof WP_Error) {
                return $t;
            }
        }
        return true;
    }
}