<?php

namespace App\Service\Assignment;

use App\Entity\Destination;
use App\Entity\StaffingRule;
use App\Enum\StaffingFee;
use App\Enum\StaffingRole;
use App\Model\PlannedAssignment;
use App\Service\Common\PickupOptions;

/**
 * Turns a staffing matrix row into the draft assignments for one travel date.
 *
 * The rules, agreed 2026-10-15 (see .ddev/plans/teamer-auto-assignments-plan.md):
 * - one assignment per role, the role's head count as its places;
 * - without split, each ski level is a Kursleitung of its own, one place;
 * - with split, a Reiseleitung takes over each level through the combined profile, one place
 *   per level, and the plain Reiseleitung keeps the remaining places;
 * - Guiding is the guiding fee on every guide-type assignment, not an assignment of its own;
 * - a date with bus travel (boarding points) gets its first boarding point pre-selected as
 *   Busbegleitung on exactly one assignment, the first guide-type one - the plain Reiseleitung
 *   where there is one. Taken from the date, not the matrix: bus travel varies between the
 *   dates of one product.
 */
final class AssignmentPlanner
{
    /**
     * @return list<PlannedAssignment>
     */
    public function plan(StaffingRule $rule, Destination $destination): array
    {
        $roles = [];
        $guides = (int) $rule->getGuides();

        if (true === $rule->isSplit()) {
            $combined = [];

            if (true === $rule->isSkiBeginner()) {
                $combined[] = StaffingRole::GUIDE_SKI_BEGINNER;
            }

            if (true === $rule->isSkiAdvanced()) {
                $combined[] = StaffingRole::GUIDE_SKI_ADVANCED;
            }

            // The matrix validation refuses more levels than guides; max() keeps a row that
            // slipped past it from planning a negative head count.
            $roles[] = [StaffingRole::GUIDE, max(0, $guides - count($combined))];

            foreach ($combined as $role) {
                $roles[] = [$role, 1];
            }
        } else {
            $roles[] = [StaffingRole::GUIDE, $guides];

            if (true === $rule->isSkiBeginner()) {
                $roles[] = [StaffingRole::SKI_BEGINNER, 1];
            }

            if (true === $rule->isSkiAdvanced()) {
                $roles[] = [StaffingRole::SKI_ADVANCED, 1];
            }
        }

        $pickup = $this->firstPickup($destination);
        $planned = [];

        foreach ($roles as [$role, $places]) {
            if (0 === $places) {
                continue;
            }

            $fees = [];

            if (true === $role->isGuide() && true === $rule->isGuiding()) {
                $fees[] = StaffingFee::GUIDING;
            }

            if (true === $role->isCourse()) {
                $fees[] = StaffingFee::COURSE;
            }

            $planned[] = new PlannedAssignment(
                $role,
                $places,
                true === $role->isGuide() ? $pickup : null,
                $fees,
            );

            if (true === $role->isGuide()) {
                $pickup = null;
            }
        }

        return $planned;
    }

    private function firstPickup(Destination $destination): ?int
    {
        return PickupOptions::inDepartureOrder($destination)[0]['busProId'] ?? null;
    }
}