<?php
declare(strict_types=1);

final class DirectAdminVacationSyncService
{
    public function __construct(
        private RuleRepository $rules,
        private DirectAdminSyncRepository $sync,
        private MailboxDirectory $mailboxes,
        private DirectAdminVacationApi $api
    ) {
    }

    public function syncUser(string $username): void
    {
        $rules = $this->rulesById($username);
        foreach ($this->sync->allRuleEntries($username) as $ruleId => $entries) {
            if (!isset($rules[$ruleId]) || empty($rules[$ruleId]['enabled'])) {
                $this->deleteEntries($username, $ruleId, $entries);
            }
        }

        foreach ($rules as $ruleId => $rule) {
            if (empty($rule['enabled'])) {
                continue;
            }
            $this->syncRule($username, $ruleId, $rule);
        }
    }

    /** @return array<string,array<string,mixed>> */
    private function rulesById(string $username): array
    {
        $out = [];
        foreach ($this->rules->all($username) as $rule) {
            $id = (string)($rule['id'] ?? '');
            if ($id !== '') {
                $out[$id] = $rule;
            }
        }
        return $out;
    }

    /** @param array<string,mixed> $rule */
    private function syncRule(string $username, string $ruleId, array $rule): void
    {
        $existing = $this->indexedEntries($this->sync->entriesForRule($username, $ruleId));
        $targets = $this->targetMailboxes($username, $rule);
        $next = [];
        foreach ($targets as $mailbox) {
            $email = strtolower((string)$mailbox['email']);
            $isTracked = isset($existing[$email]);
            if (!$isTracked && $this->api->vacationExists($username, $email)) {
                throw new RuntimeException('Untracked DirectAdmin vacation already exists for ' . $email);
            }
            $this->api->saveVacation($username, $email, $rule, $isTracked);
            $next[] = [
                'rule_id' => $ruleId,
                'domain' => (string)$mailbox['domain'],
                'mailbox' => (string)$mailbox['mailbox'],
                'email' => $email,
                'api_key' => $email,
                'last_sync_at' => time(),
            ];
            unset($existing[$email]);
        }
        foreach ($existing as $entry) {
            $this->api->deleteVacation($username, (string)$entry['email']);
        }
        $this->sync->replaceRuleEntries($username, $ruleId, $next);
    }

    /** @param array<int,array<string,mixed>> $entries */
    private function deleteEntries(string $username, string $ruleId, array $entries): void
    {
        foreach ($entries as $entry) {
            $email = (string)($entry['email'] ?? $entry['api_key'] ?? '');
            if ($email !== '') {
                $this->api->deleteVacation($username, $email);
            }
        }
        $this->sync->deleteRuleEntries($username, $ruleId);
    }

    /** @param array<int,array<string,mixed>> $entries @return array<string,array<string,mixed>> */
    private function indexedEntries(array $entries): array
    {
        $out = [];
        foreach ($entries as $entry) {
            $email = strtolower((string)($entry['email'] ?? $entry['api_key'] ?? ''));
            if ($email !== '') {
                $out[$email] = $entry + ['email' => $email];
            }
        }
        return $out;
    }

    /** @param array<string,mixed> $rule @return array<int,array{domain:string,mailbox:string,email:string}> */
    private function targetMailboxes(string $username, array $rule): array
    {
        if (empty($rule['dynamic_scope']) && isset($rule['mailbox_snapshot']) && is_array($rule['mailbox_snapshot'])) {
            return array_values(array_filter($rule['mailbox_snapshot'], static function (mixed $mailbox): bool {
                return is_array($mailbox)
                    && isset($mailbox['domain'], $mailbox['mailbox'], $mailbox['email'])
                    && filter_var((string)$mailbox['email'], FILTER_VALIDATE_EMAIL);
            }));
        }
        return $this->mailboxes->mailboxesForUser($username);
    }
}