<?php

declare(strict_types=1);

namespace BattleForge\Domain;

use InvalidArgumentException;

final readonly class Scenario
{
    /**
     * @param list<UnitState> $units
     * @param array<string, DeploymentZone> $deploymentZones
     * @param array<string, ObjectiveMarker> $objectives
     */
    public function __construct(
        public string $id,
        public string $name,
        public Battlefield $battlefield,
        public array $units,
        public array $deploymentZones,
        public array $objectives,
        public VictoryCondition $victoryCondition,
        public int $holdRoundsRequired,
    ) {
        if ($id === '') {
            throw new InvalidArgumentException('Scenario id cannot be empty.');
        }

        if ($name === '') {
            throw new InvalidArgumentException('Scenario name cannot be empty.');
        }

        if (!array_is_list($units)) { // @phpstan-ignore function.alreadyNarrowedType (Runtime guard: PHPDoc is not a runtime contract for JSON-sourced arrays in Plan 4.)
            throw new InvalidArgumentException('Scenario units must be a list.');
        }

        if ($deploymentZones === []) {
            throw new InvalidArgumentException('Scenario must declare at least one deployment zone.');
        }

        if (count($deploymentZones) !== 2) {
            throw new InvalidArgumentException('Scenarios must declare exactly two deployment zones.');
        }

        if ($holdRoundsRequired < 1) {
            throw new InvalidArgumentException('Hold rounds required must be at least 1.');
        }

        if ($victoryCondition === VictoryCondition::HoldObjective && count($this->objectives) !== 1) {
            throw new InvalidArgumentException('Hold objective victory requires exactly one objective.');
        }

        if ($victoryCondition === VictoryCondition::EliminateAll && $this->objectives !== []) {
            throw new InvalidArgumentException('Eliminate all victory does not allow objectives.');
        }

        $unitsByTeam = $this->groupUnitsByTeam($units);

        foreach ($unitsByTeam as $teamId => $teamUnits) {
            if (count($teamUnits) < 3 || count($teamUnits) > 6) {
                throw new InvalidArgumentException("Team {$teamId} must have between 3 and 6 units.");
            }

            if (!isset($deploymentZones[$teamId])) {
                throw new InvalidArgumentException("Team {$teamId} is missing a deployment zone.");
            }
        }

        foreach ($units as $unit) {
            if (!$this->battlefield->contains($unit->position)) {
                throw new InvalidArgumentException("Unit {$unit->id} is outside the battlefield.");
            }

            $template = ArchetypeCatalog::templates()[$unit->archetype->value] ?? null;
            if ($template === null) {
                throw new InvalidArgumentException("Unit {$unit->id} uses an unknown archetype.");
            }

            if ($unit->maxHealth < $template->minHealth || $unit->maxHealth > $template->maxHealth) {
                throw new InvalidArgumentException("Unit {$unit->id} health is outside archetype bounds.");
            }
            if ($unit->attack < $template->minAttack || $unit->attack > $template->maxAttack) {
                throw new InvalidArgumentException("Unit {$unit->id} attack is outside archetype bounds.");
            }
            if ($unit->defense < $template->minDefense || $unit->defense > $template->maxDefense) {
                throw new InvalidArgumentException("Unit {$unit->id} defense is outside archetype bounds.");
            }
            if ($unit->speed < $template->minSpeed || $unit->speed > $template->maxSpeed) {
                throw new InvalidArgumentException("Unit {$unit->id} speed is outside archetype bounds.");
            }

            foreach ($unit->abilities as $ability) {
                if (!in_array($ability, $template->allowedAbilities, true)) {
                    throw new InvalidArgumentException("Unit {$unit->id} has an ability that its archetype forbids.");
                }
            }

            $zone = $deploymentZones[$unit->teamId] ?? null;
            if ($zone === null || !$zone->contains($unit->position)) {
                throw new InvalidArgumentException("Unit {$unit->id} must start inside team {$unit->teamId} deployment zone.");
            }
        }

        foreach ($objectives as $objective) {
            if (!$this->battlefield->contains($objective->position)) {
                throw new InvalidArgumentException("Objective {$objective->id} is outside the battlefield.");
            }
        }
    }

    public function startMatch(string $activeTeamId): MatchState
    {
        $resetUnits = [];

        foreach ($this->units as $unit) {
            $resetUnits[] = new UnitState(
                $unit->id,
                $unit->teamId,
                $unit->position,
                $unit->maxHealth,
                $unit->maxHealth,
                $unit->attack,
                $unit->defense,
                $unit->speed,
                2,
                false,
                $unit->archetype,
                $unit->abilities,
                0,
                false,
            );
        }

        return new MatchState(
            battlefield: $this->battlefield,
            units: $resetUnits,
            activeTeamId: $activeTeamId,
            objectives: $this->objectives,
            victoryCondition: $this->victoryCondition,
            holdRoundsRequired: $this->holdRoundsRequired,
        );
    }

    /**
     * @param list<UnitState> $units
     * @return array<string, list<UnitState>>
     */
    private function groupUnitsByTeam(array $units): array
    {
        $grouped = [];

        foreach ($units as $unit) {
            $grouped[$unit->teamId] ??= [];
            $grouped[$unit->teamId][] = $unit;
        }

        return $grouped;
    }
}