<?php
declare(strict_types=1);
namespace App\Dashboard;

use App\Http\{Request, Response};
use App\Auth\SessionStore;
use App\Repository\EventRepository;

/**
 * GET /api/report?days=N — the safety operations report: the numbers a 안전관리자 takes
 * into the weekly safety meeting. Everything the system collects, folded into management
 * indicators over one window: incident counts, response time, the near-miss pyramid,
 * false-positive rate, posture-load exposure, occupancy-rule violations.
 */
final class ReportController
{
    private const DEFAULT_DAYS = 7;
    private const MAX_DAYS = 90;
    private const TOP_CAMERAS = 8;
    private const OCCUPANCY_TYPES = ['lone_worker', 'overcapacity', 'overstay'];
    private const ERGO_KEYS = ['observed_s', 'trunk_high_s', 'trunk_mod_s', 'arm_high_s', 'squat_s'];
    // 전조(precursor) 그룹: 부상 없이 끝났지만 사고로 이어질 수 있던 신호 — 급증 경보와
    // 시간 패턴의 대상. 사고 자체(fall/no_motion/ghost/immobility/pinch)는 제외.
    private const PRECURSOR_TYPES = ['near_fall', 'zone_warning', 'zone_restricted',
        'lone_worker', 'overcapacity', 'overstay'];
    private const SPIKE_BASELINE_WEEKS = 4;
    private const SPIKE_MIN_COUNT = 5;     // 이보다 적으면 통계가 아니라 소음
    private const SPIKE_RATIO = 1.5;
    private const PATTERN_LIMIT = 20000;

    public function __construct(private EventRepository $events, private SessionStore $sess) {}

    public function json(Request $req): Response
    {
        if ($this->sess->get('user_id') === null) return Response::json(['error' => 'unauthorized'], 401);
        $days = self::clampDays($req->query('days'));
        $scope = $this->sess->get('site_scope');
        $site = is_string($scope) ? $scope : null;
        $now = time();
        $since = (float)($now - $days * 86400);
        $s = $this->events->reportSummary($since, $site, self::TOP_CAMERAS);
        // 직전 동일 길이 기간 — KPI의 "지난 기간 대비" 추이. 같은 집계를 상한만 걸어 재사용.
        $prev = $this->events->reportSummary((float)($now - 2 * $days * 86400), $site,
            self::TOP_CAMERAS, $since);

        $severityTotals = ['critical' => 0, 'high' => 0, 'warning' => 0, 'info' => 0];
        $typeCounts = [];
        $unacked = 0; $fpTagged = 0; $total = 0;
        $nearFall = 0; $falls = 0;
        $occupancy = array_fill_keys(self::OCCUPANCY_TYPES, 0);
        foreach ($s['by_type'] as $row) {
            $total += $row['count'];
            $unacked += $row['unacked'];
            $fpTagged += $row['fp'];
            if (isset($severityTotals[$row['severity']])) $severityTotals[$row['severity']] += $row['count'];
            $typeCounts[$row['event_type']] = ($typeCounts[$row['event_type']] ?? 0) + $row['count'];
            if ($row['event_type'] === 'near_fall') $nearFall += $row['count'];
            if (in_array($row['event_type'], ['fall', 'no_motion'], true)) $falls += $row['count'];
            if (in_array($row['event_type'], self::OCCUPANCY_TYPES, true)) {
                $occupancy[$row['event_type']] += $row['count'];
            }
        }
        // ergo_report is bookkeeping, not a detection — it must not inflate "감지 N건".
        $ergoReports = $typeCounts['ergo_report'] ?? 0;
        $total -= $ergoReports;
        if (isset($severityTotals['info'])) $severityTotals['info'] = max(0, $severityTotals['info'] - $ergoReports);
        unset($typeCounts['ergo_report']);
        arsort($typeCounts);

        $ergo = array_fill_keys(self::ERGO_KEYS, 0.0);
        foreach ($s['ergo_metrics'] as $m) {
            foreach (self::ERGO_KEYS as $k) $ergo[$k] += (float)($m[$k] ?? 0);
        }
        $ergo = array_map(static fn ($v) => round($v, 1), $ergo);

        // 이전 기간 요약 — KPI 추이에 필요한 축만 (전체 by_type 재전송은 낭비).
        $prevSeverity = ['critical' => 0, 'high' => 0];
        $prevTotal = 0; $prevFp = 0; $prevNearFall = 0;
        foreach ($prev['by_type'] as $row) {
            if ($row['event_type'] === 'ergo_report') continue;
            $prevTotal += $row['count'];
            $prevFp += $row['fp'];
            if (isset($prevSeverity[$row['severity']])) $prevSeverity[$row['severity']] += $row['count'];
            if ($row['event_type'] === 'near_fall') $prevNearFall += $row['count'];
        }

        // 시간 패턴 + 전조 급증. 버킷팅은 PHP에서(서버 로컬 시각 = 현장 시간대) — SQL은
        // 이식성 유지. 급증 기준선은 리포트 기간과 무관하게 최근 5주로 고정한다.
        $pattern = self::buildPattern($this->events->occurrenceTimes($since, $site, self::PATTERN_LIMIT));
        $spike = self::precursorSpike(
            $this->events->occurrenceTimes((float)($now - (self::SPIKE_BASELINE_WEEKS + 1) * 7 * 86400),
                $site, self::PATTERN_LIMIT), $now);

        return Response::json([
            'days' => $days,
            'generated_at' => time(),
            'totals' => ['events' => $total, 'unacked' => $unacked] + $severityTotals,
            'by_type' => $typeCounts,
            'by_camera' => $s['by_camera'],
            'tta' => [
                'acked' => $s['tta']['acked'],
                'avg_s' => $s['tta']['avg_s'] !== null ? round($s['tta']['avg_s'], 1) : null,
                'max_s' => $s['tta']['max_s'] !== null ? round($s['tta']['max_s'], 1) : null,
            ],
            'near_miss' => ['near_fall' => $nearFall, 'incidents' => $falls],
            'fp' => ['tagged' => $fpTagged, 'total' => $total],
            'ergo' => $ergo,
            'occupancy' => $occupancy,
            'previous' => [
                'events' => $prevTotal,
                'critical' => $prevSeverity['critical'], 'high' => $prevSeverity['high'],
                'near_fall' => $prevNearFall,
                'fp' => ['tagged' => $prevFp, 'total' => $prevTotal],
                'tta_avg_s' => $prev['tta']['avg_s'] !== null ? round($prev['tta']['avg_s'], 1) : null,
            ],
            'pattern' => $pattern,
            'precursor_alert' => $spike,
        ], 200);
    }

    /** 요일(0=월)×시간(0..23) 발생 밀도 그리드 — 서버 로컬 시각 기준. */
    private static function buildPattern(array $times): array
    {
        $grid = array_fill(0, 7, array_fill(0, 24, 0));
        $max = 0;
        foreach ($times as $t) {
            $ts = (int)$t['occurred_at'];
            $d = (int)date('N', $ts) - 1;
            $h = (int)date('G', $ts);
            $grid[$d][$h]++;
            if ($grid[$d][$h] > $max) $max = $grid[$d][$h];
        }
        return ['grid' => $grid, 'max' => $max];
    }

    /**
     * 전조 급증: 최근 7일 전조 건수를 그 이전 4주의 주평균과 비교. 사고가 나기 전에 올리는
     * 경보이므로 보수적으로 — 표본이 SPIKE_MIN_COUNT 미만이면 절대 울리지 않는다.
     */
    private static function precursorSpike(array $times, int $now): array
    {
        $weekAgo = $now - 7 * 86400;
        $thisWeek = 0; $baselineTotal = 0;
        foreach ($times as $t) {
            if (!in_array($t['event_type'], self::PRECURSOR_TYPES, true)) continue;
            if ($t['occurred_at'] >= $weekAgo) $thisWeek++;
            else $baselineTotal++;
        }
        $baselineAvg = $baselineTotal / self::SPIKE_BASELINE_WEEKS;
        $ratio = $baselineAvg > 0 ? $thisWeek / $baselineAvg : null;
        $alert = $thisWeek >= self::SPIKE_MIN_COUNT
            && ($baselineAvg == 0.0 || $ratio >= self::SPIKE_RATIO);
        return ['this_week' => $thisWeek, 'baseline_weekly_avg' => round($baselineAvg, 1),
                'ratio' => $ratio !== null ? round($ratio, 2) : null, 'alert' => $alert];
    }

    private static function clampDays(mixed $raw): int
    {
        if ($raw === null || $raw === '' || !is_numeric($raw)) return self::DEFAULT_DAYS;
        return max(1, min(self::MAX_DAYS, (int)$raw));
    }
}