<?php
declare(strict_types=1);

class EscalationService
{
    private TaskAssignmentRepository $assignmentRepo;
    private TaskRuleRepository $ruleRepo;
    private TaskChangeLogRepository $changeLogRepo;

    public function __construct(
        TaskAssignmentRepository $assignmentRepo,
        TaskRuleRepository $ruleRepo,
        TaskChangeLogRepository $changeLogRepo
    ) {
        $this->assignmentRepo = $assignmentRepo;
        $this->ruleRepo = $ruleRepo;
        $this->changeLogRepo = $changeLogRepo;
    }

    public function recalculateEscalations(): int
    {
        $summary = $this->recalculateEscalationsDetailed(true, null);
        return (int) ($summary['changed_assignments'] ?? 0);
    }

    public function recalculateEscalationsDetailed(bool $apply = true, ?int $taskId = null): array
    {
        $now = new DateTimeImmutable();
        $auth = TaskCertAuthContext::fromGlobals();
        $changedBy = $auth->isLoggedIn() ? $auth->contactId() : 0;
        $scope = $taskId !== null && $taskId > 0 ? 'single_task' : 'all_active_tasks';
        $jobRunId = $this->createJobRunId();
        $trigger = PHP_SAPI === 'cli' ? 'cron_cli' : 'admin_ui';

        $summary = [
            'apply' => $apply,
            'task_id' => $taskId !== null && $taskId > 0 ? $taskId : null,
            'scope' => $scope,
            'job_run_id' => $jobRunId,
            'trigger' => $trigger,
            'processed_candidates' => 0,
            'changed_assignments' => 0,
            'entered_count' => 0,
            'cleared_count' => 0,
            'tasks' => [],
        ];
        $taskSummary = [];

        foreach ($this->assignmentRepo->findEscalationCandidates($taskId) as $assignment) {
            $summary['processed_candidates']++;
            $taskId = (int) $assignment['task_id'];
            $dueAtRaw = (string) ($assignment['due_at'] ?? '');
            if ($dueAtRaw === '') {
                continue;
            }

            try {
                $dueAt = new DateTimeImmutable($dueAtRaw);
            } catch (Throwable $throwable) {
                continue;
            }
            $graceUntilRaw = trim((string) ($assignment['grace_until'] ?? ''));
            $graceUntil = null;
            if ($graceUntilRaw !== '') {
                try {
                    $graceUntil = new DateTimeImmutable($graceUntilRaw);
                } catch (Throwable $throwable) {
                    $graceUntil = null;
                }
            }
            $effectiveDueAt = ($graceUntil !== null && $graceUntil > $dueAt) ? $graceUntil : $dueAt;
            $isOverdue = $now > $effectiveDueAt;
            $assignmentId = (int) $assignment['id'];
            $currentStatus = (string) ($assignment['status'] ?? '');
            $oldLevel = (int) ($assignment['escalation_level'] ?? 0);
            $assignmentChanged = false;
            $assignmentEntered = false;
            $assignmentCleared = false;

            if (!$isOverdue) {
                if ($currentStatus === 'overdue') {
                    if ($apply) {
                        $this->assignmentRepo->clearOverdue($assignmentId);
                    }
                    $assignmentChanged = true;
                }

                if ($oldLevel !== 0) {
                    if ($apply) {
                        $this->assignmentRepo->clearEscalation($assignmentId);
                        $this->assignmentRepo->addEscalationEvent(
                            $assignmentId,
                            0,
                            'cleared',
                            ['reason' => 'due_date_not_reached']
                        );
                    }
                    $assignmentChanged = true;
                    $assignmentCleared = true;
                }

                $this->collectEscalationStats($summary, $taskSummary, $taskId, $assignmentChanged, $assignmentEntered, $assignmentCleared);
                continue;
            }

            $overdueAtRaw = trim((string) ($assignment['overdue_at'] ?? ''));
            $overdueAt = $overdueAtRaw !== '' ? new DateTimeImmutable($overdueAtRaw) : $effectiveDueAt;
            if ($currentStatus !== 'overdue') {
                $overdueAt = $effectiveDueAt;
                if ($apply) {
                    $this->assignmentRepo->markOverdue($assignmentId, $overdueAt->format('Y-m-d H:i:s'));
                }
                $assignmentChanged = true;
            } elseif ($overdueAtRaw === '') {
                $overdueAt = $effectiveDueAt;
                if ($apply) {
                    $this->assignmentRepo->markOverdue($assignmentId, $overdueAt->format('Y-m-d H:i:s'));
                }
                $assignmentChanged = true;
            }

            $policy = $this->ruleRepo->getReminderPolicyByTask($taskId);
            if ($policy === null || (int) ($policy['active'] ?? 1) !== 1) {
                if ($oldLevel !== 0) {
                    if ($apply) {
                        $this->assignmentRepo->clearEscalation($assignmentId);
                        $this->assignmentRepo->addEscalationEvent(
                            $assignmentId,
                            0,
                            'cleared',
                            ['reason' => 'policy_inactive']
                        );
                    }
                    $assignmentChanged = true;
                    $assignmentCleared = true;
                }

                $this->collectEscalationStats($summary, $taskSummary, $taskId, $assignmentChanged, $assignmentEntered, $assignmentCleared);
                continue;
            }

            $daysOverdue = (int) floor(($now->getTimestamp() - $overdueAt->getTimestamp()) / 86400);
            $firstDays = max(0, (int) ($policy['first_escalation_days'] ?? 0));
            $stepDays = max(1, (int) ($policy['step_days'] ?? 7));
            $maxLevel = max(1, (int) ($policy['max_level'] ?? 3));

            if ($daysOverdue < $firstDays) {
                $newLevel = 0;
            } else {
                $newLevel = 1 + (int) floor(($daysOverdue - $firstDays) / $stepDays);
                $newLevel = min($newLevel, $maxLevel);
            }

            if ($newLevel !== $oldLevel) {
                $assignmentChanged = true;
                if ($newLevel === 0) {
                    if ($apply) {
                        $this->assignmentRepo->clearEscalation($assignmentId);
                        $this->assignmentRepo->addEscalationEvent(
                            $assignmentId,
                            0,
                            'cleared',
                            [
                                'days_overdue' => $daysOverdue,
                                'old_level' => $oldLevel,
                            ]
                        );
                    }
                    $assignmentCleared = true;
                } else {
                    if ($apply) {
                        $this->assignmentRepo->setEscalationLevel($assignmentId, $newLevel);
                        $this->assignmentRepo->addEscalationEvent(
                            $assignmentId,
                            $newLevel,
                            'entered',
                            [
                                'days_overdue' => $daysOverdue,
                                'old_level' => $oldLevel,
                                'new_level' => $newLevel,
                            ]
                        );
                    }
                    $assignmentEntered = true;
                }
            }

            $this->collectEscalationStats($summary, $taskSummary, $taskId, $assignmentChanged, $assignmentEntered, $assignmentCleared);
        }

        $summary['tasks'] = array_values($taskSummary);

        if (!$apply) {
            return $summary;
        }

        foreach ($summary['tasks'] as $taskStat) {
            $changedAssignments = (int) ($taskStat['changed_assignments'] ?? 0);
            if ($changedAssignments <= 0) {
                continue;
            }

            $taskIdForLog = (int) ($taskStat['task_id'] ?? 0);
            if ($taskIdForLog <= 0) {
                continue;
            }

            $this->changeLogRepo->create(
                $taskIdForLog,
                'recalculate_escalations_apply',
                $changedBy,
                null,
                null,
                [
                    'changed_assignments' => $changedAssignments,
                    'entered_count' => (int) ($taskStat['entered_count'] ?? 0),
                    'cleared_count' => (int) ($taskStat['cleared_count'] ?? 0),
                    'scope' => $scope,
                    'trigger' => $trigger,
                    'job_run_id' => $jobRunId,
                ]
            );
        }

        return $summary;
    }

    private function collectEscalationStats(
        array &$summary,
        array &$taskSummary,
        int $taskId,
        bool $assignmentChanged,
        bool $assignmentEntered,
        bool $assignmentCleared
    ): void {
        if ($taskId <= 0) {
            return;
        }

        if (!isset($taskSummary[$taskId])) {
            $taskSummary[$taskId] = [
                'task_id' => $taskId,
                'changed_assignments' => 0,
                'entered_count' => 0,
                'cleared_count' => 0,
            ];
        }

        if ($assignmentChanged) {
            $summary['changed_assignments']++;
            $taskSummary[$taskId]['changed_assignments']++;
        }

        if ($assignmentEntered) {
            $summary['entered_count']++;
            $taskSummary[$taskId]['entered_count']++;
        }

        if ($assignmentCleared) {
            $summary['cleared_count']++;
            $taskSummary[$taskId]['cleared_count']++;
        }
    }

    private function createJobRunId(): string
    {
        try {
            $entropy = bin2hex(random_bytes(6));
        } catch (Throwable $throwable) {
            $entropy = substr(sha1((string) microtime(true)), 0, 12);
        }

        return 'esc-' . date('YmdHis') . '-' . $entropy;
    }
}