<?php
namespace ABeCe\Booking\Service;
use ABeCe\Booking\Support\Time;
/** Interval arithmetic, never booking slots; blocks are subtracted as a union. */
final class StatisticsUtilizationService {
 public function __construct(private readonly OperatingScheduleService $schedule){}
 public static function subtract(array $intervals,array $blocks): array {
  foreach($blocks as [$start,$end]){$next=[];foreach($intervals as [$a,$b]){if($end<=$a||$start>=$b){$next[]=[$a,$b];continue;}if($a<$start)$next[]=[$a,min($start,$b)];if($end<$b)$next[]=[max($end,$a),$b];}$intervals=$next;}return $intervals;
 }
 /** Split actual instants at hour boundaries; repeated DST hours both contribute. */
 public static function hourParts(int $start,int $end,callable $consume): void {
  while($start<$end){$local=Time::timestamp($start);$next=min($end,$start+3600-(int)$local->format('i')*60-(int)$local->format('s'));$consume((int)$local->format('N'),(int)$local->format('G'),$next-$start,$local->format('Y-m-d'));$start=$next;}
 }
 public function calculate(array $resources,array $data,StatisticsFilter $f): array {
  $hours=[];$exceptions=[];$blocks=[];
  foreach(['hours','exceptions'] as $kind)foreach($data[$kind] as $row){$row['resource_id']=$row['resource_id']===null?null:(int)$row['resource_id'];if($kind==='hours')$hours[(int)$row['day_of_week']][]=$row;else $exceptions[$row['exception_date']][]=$row;}
  foreach($data['blocks'] as $row)$blocks[$row['resource_id']??0][]=[Time::fromSql($row['starts_at']),Time::fromSql($row['ends_at'])];
  $capacity=[];$heat=array_fill(0,168,0);$last=$f->values['date_to'];
  foreach($resources as $r){$id=(int)$r['id'];$capacity[$id]=['available_seconds'=>0,'blocked_seconds'=>0];if(!$r['is_active']||!$r['is_visible']||!$r['is_bookable'])continue;
   for($day=Time::day($f->values['date_from']);$day&&$day->format('Y-m-d')<=$last;$day=Time::nextDay($day->format('Y-m-d'))){$date=$day->format('Y-m-d');$intervals=$this->schedule->intervalsFromRows($id,$date,$hours[(int)$day->format('N')]??[],$exceptions[$date]??[]);$free=self::subtract($intervals,array_merge($blocks[0]??[],$blocks[$id]??[]));
    $original=0;foreach($intervals as [$a,$b])$original+=$b-$a;$available=0;
    foreach($free as [$a,$b]){$available+=$b-$a;self::hourParts($a,$b,static function($w,$h,$s)use(&$heat){$heat[($w-1)*24+$h]+=$s;});}
    $capacity[$id]['available_seconds']+=$available;$capacity[$id]['blocked_seconds']+=$original-$available;
   }
  }
  return ['resources'=>$capacity,'heat'=>$heat];
 }
}