<?php

use Carbon\Carbon;
use Illuminate\Support\Collection;

/**
 * Determine the age group based on birth year.
 *
 * @param int $birthYear
 * @param int $competitionYear
 * @return string
 */
function getAgeGroupByBirthYear(int $birthYear, int $competitionYear = 2025): string
{
    // Age group birth year ranges (adjust as per your competition)
    $ageGroups = [
        'child'  => [2014, 2019],
        'cadet'  => [2011, 2013],
        'junior' => [2008, 2010],
        'senior' => [0, 2007],
    ];

    foreach ($ageGroups as $group => [$startYear, $endYear]) {
        if ($startYear <= $birthYear && $birthYear <= $endYear) {
            return $group;
        }
    }
    return 'unknown';
}

/**
 * Assign weight class based on age group, gender, and weight.
 *
 * @param string $ageGroup
 * @param string $gender Lowercase 'male' or 'female'
 * @param float $weight
 * @return string Weight class label or 'unknown'
 */
function assignWeightClass(string $ageGroup, string $gender, float $weight): string
{
    $weightClasses = [
        'senior' => [
            'male' => [
                ['min' => 0,    'max' => 54,   'label' => '-54kg'],
                ['min' => 54,   'max' => 58,   'label' => '-58kg'],
                ['min' => 58,   'max' => 63,   'label' => '-63kg'],
                ['min' => 63,   'max' => 68,   'label' => '-68kg'],
                ['min' => 68,   'max' => 74,   'label' => '-74kg'],
                ['min' => 74,   'max' => 80,   'label' => '-80kg'],
                ['min' => 80,   'max' => 87,   'label' => '-87kg'],
                ['min' => 87,   'max' => INF,  'label' => '+87kg'],
            ],
            'female' => [
                ['min' => 0,    'max' => 46,   'label' => '-46kg'],
                ['min' => 46,   'max' => 49,   'label' => '-49kg'],
                ['min' => 49,   'max' => 53,   'label' => '-53kg'],
                ['min' => 53,   'max' => 57,   'label' => '-57kg'],
                ['min' => 57,   'max' => 62,   'label' => '-62kg'],
                ['min' => 62,   'max' => 67,   'label' => '-67kg'],
                ['min' => 67,   'max' => 73,   'label' => '-73kg'],
                ['min' => 73,   'max' => INF,  'label' => '+73kg'],
            ],
        ],
        'junior' => [
            'male' => [
                ['min' => 0,  'max' => 45,  'label' => '-45kg'],
                ['min' => 45, 'max' => 48,  'label' => '-48kg'],
                ['min' => 48, 'max' => 51,  'label' => '-51kg'],
                ['min' => 51, 'max' => 55,  'label' => '-55kg'],
                ['min' => 55, 'max' => 59,  'label' => '-59kg'],
                ['min' => 59, 'max' => 63,  'label' => '-63kg'],
                ['min' => 63, 'max' => 68,  'label' => '-68kg'],
                ['min' => 68, 'max' => 73,  'label' => '-73kg'],
                ['min' => 73, 'max' => 78,  'label' => '-78kg'],
                ['min' => 78, 'max' => INF, 'label' => '+78kg'],
            ],
            'female' => [
                ['min' => 0,  'max' => 42,  'label' => '-42kg'],
                ['min' => 42, 'max' => 44,  'label' => '-44kg'],
                ['min' => 44, 'max' => 46,  'label' => '-46kg'],
                ['min' => 46, 'max' => 49,  'label' => '-49kg'],
                ['min' => 49, 'max' => 52,  'label' => '-52kg'],
                ['min' => 52, 'max' => 55,  'label' => '-55kg'],
                ['min' => 55, 'max' => 59,  'label' => '-59kg'],
                ['min' => 59, 'max' => 63,  'label' => '-63kg'],
                ['min' => 63, 'max' => 68,  'label' => '-68kg'],
                ['min' => 68, 'max' => INF, 'label' => '+68kg'],
            ],
        ],
        'cadet' => [
            'male' => [
                ['min' => 0,   'max' => 33,  'label' => '-33kg'],
                ['min' => 33,  'max' => 37,  'label' => '-37kg'],
                ['min' => 37,  'max' => 41,  'label' => '-41kg'],
                ['min' => 41,  'max' => 45,  'label' => '-45kg'],
                ['min' => 45,  'max' => 49,  'label' => '-49kg'],
                ['min' => 49,  'max' => 53,  'label' => '-53kg'],
                ['min' => 53,  'max' => 57,  'label' => '-57kg'],
                ['min' => 57,  'max' => 61,  'label' => '-61kg'],
                ['min' => 61,  'max' => 65,  'label' => '-65kg'],
                ['min' => 65,  'max' => INF, 'label' => '+65kg'],
            ],
            'female' => [
                ['min' => 0,   'max' => 29,  'label' => '-29kg'],
                ['min' => 29,  'max' => 33,  'label' => '-33kg'],
                ['min' => 33,  'max' => 37,  'label' => '-37kg'],
                ['min' => 37,  'max' => 41,  'label' => '-41kg'],
                ['min' => 41,  'max' => 44,  'label' => '-44kg'],
                ['min' => 44,  'max' => 47,  'label' => '-47kg'],
                ['min' => 47,  'max' => 51,  'label' => '-51kg'],
                ['min' => 51,  'max' => 55,  'label' => '-55kg'],
                ['min' => 55,  'max' => 59,  'label' => '-59kg'],
                ['min' => 59,  'max' => INF, 'label' => '+59kg'],
            ],
        ],
        'child' => [
            'male' => [
                ['min' => 0,   'max' => 24,  'label' => '-24kg'],
                ['min' => 24,  'max' => 28,  'label' => '-28kg'],
                ['min' => 28,  'max' => 32,  'label' => '-32kg'],
                ['min' => 32,  'max' => 36,  'label' => '-36kg'],
                ['min' => 36,  'max' => 40,  'label' => '-40kg'],
                ['min' => 40,  'max' => 44,  'label' => '-44kg'],
                ['min' => 44,  'max' => 48,  'label' => '-48kg'],
                ['min' => 48,  'max' => 52,  'label' => '-52kg'],
                ['min' => 52,  'max' => 56,  'label' => '-56kg'],
                ['min' => 56,  'max' => INF, 'label' => '+56kg'],
            ],
            'female' => [
                ['min' => 0,    'max' => 29,  'label' => '-29kg'],
                ['min' => 29,   'max' => 33,  'label' => '29-33kg'],
                ['min' => 33,   'max' => 37,  'label' => '33-37kg'],
                ['min' => 37,   'max' => 41,  'label' => '37-41kg'],
                ['min' => 41,   'max' => 44,  'label' => '41-44kg'],
                ['min' => 44,   'max' => 47,  'label' => '44-47kg'],
                ['min' => 47,   'max' => 51,  'label' => '47-51kg'],
                ['min' => 51,   'max' => 55,  'label' => '51-55kg'],
                ['min' => 55,   'max' => 59,  'label' => '55-59kg'],
                ['min' => 59,   'max' => INF, 'label' => '+59kg'],
            ],
        ],
    ];

    if (!isset($weightClasses[$ageGroup][$gender])) {
        return 'unknown';
    }

    foreach ($weightClasses[$ageGroup][$gender] as $class) {
        if ($weight > $class['min'] && $weight <= $class['max']) {
            return $class['label'];
        }
    }

    return 'unknown';
}

/**
 * Classify a single fighter by age group, gender, birth year, and weight class.
 *
 * @param array $fighter Array with keys 'date_of_birth', 'gender', 'weight'.
 * @param int $competitionYear
 * @return array Augmented fighter data.
 */
function classifyFighter(array $fighter, int $competitionYear = 2025): array
{
    $dob = Carbon::parse($fighter['date_of_birth']);
    $birthYear = $dob->year;
    $ageGroup = getAgeGroupByBirthYear($birthYear, $competitionYear);
    $gender = strtolower($fighter['gender']);
    $weight = floatval($fighter['weight']);
    $weightClass = assignWeightClass($ageGroup, $gender, $weight);

    return array_merge($fighter, [
        'age_group' => $ageGroup,
        'birth_year' => $birthYear,
        'gender' => $gender,
        'weight_class' => $weightClass,
    ]);
}

/**
 * Group fighters by age group, gender, and weight class,
 * then generate a Taekwondo single-elimination draw with colors.
 *
 * @param array $fighters
 * @param int $competitionYear
 * @return array Grouped fighters with tournament draws.
 */
function groupFightersWithTaekwondoDraw(array $fighters, int $competitionYear = 2025): array
{
    $classified = array_map(fn($f) => classifyFighter($f, $competitionYear), $fighters);
    $collection = collect($classified);

    $grouped = $collection->groupBy([
        'age_group',
        'gender',
        'weight_class',
    ]);

    $result = [];

    foreach ($grouped as $ageGroup => $genders) {
        foreach ($genders as $gender => $weightClasses) {
            foreach ($weightClasses as $weightClass => $fightersInGroup) {
                // Important: Reset array keys to prevent undefined index errors
                $fightersArray = array_values($fightersInGroup->toArray());

                // Create Taekwondo-style draw
                $draw = createTaekwondoDraw($fightersArray);

                $result[] = [
                    'age_group' => $ageGroup,
                    'gender' => $gender,
                    'weight_class' => $weightClass,
                    'fighters' => $fightersArray,
                    'tournament_draw' => $draw,
                ];
            }
        }
    }

    return $result;
}

/**
 * Create a Taekwondo single-elimination tournament draw.
 * Assign colors (red/blue) properly to matches.
 * Fixes index issues by ensuring the fighters array is properly zero-based and extends to bracket size with byes.
 *
 * @param array $fighters Array of fighters in a single group
 * @return array Tournament draw data with rounds and matches.
 */
function createTaekwondoDraw(array $fighters): array
{
    // Reset keys to zero-indexed array to avoid undefined index errors
    $fighters = array_values($fighters);

    $numFighters = count($fighters);

    $bracketSize = 1;
    while ($bracketSize < $numFighters) {
        $bracketSize <<= 1;
    }

    $numByes = $bracketSize - $numFighters;

    // Add byes as null if needed
    for ($i = 0; $i < $numByes; $i++) {
        $fighters[] = null; // represent bye by null
    }

    $numMatches = $bracketSize / 2;
    $matches = [];

    for ($i = 0; $i < $numMatches; $i++) {
        $p1Index = 2 * $i;
        $p2Index = 2 * $i + 1;

        $player1 = isset($fighters[$p1Index]) ? $fighters[$p1Index] : null;
        $player2 = isset($fighters[$p2Index]) ? $fighters[$p2Index] : null;

        $matches[] = [
            'match_number' => $i + 1,
            'player1' => $player1 ? ['fighter_data' => $player1, 'color' => 'red'] : null,
            'player2' => $player2 ? ['fighter_data' => $player2, 'color' => 'blue'] : null,
            'winner' => null,
        ];
    }

    $totalRounds = (int) log($bracketSize, 2);

    $rounds = [
        [
            'round' => 1,
            'matches' => $matches,
        ]
    ];

    // Add empty rounds for future matches (could be filled dynamically)
    for ($r = 2; $r <= $totalRounds; $r++) {
        $rounds[] = [
            'round' => $r,
            'matches' => [],
        ];
    }

    return [
        'totalRounds' => $totalRounds,
        'rounds' => $rounds,
        'bracketSize' => $bracketSize,
        'originalFightersCount' => $numFighters,
    ];
}