<?php

namespace App\Services\Survey;

class SurveyStatistics
{
    public static function summarize(array $questions, iterable $responses): array
    {
        $stats = [];
        foreach ($questions as $q) {
            $q['stats'] = self::emptyStats($q);
            if ($q['edit_input'] === 'multi_dimension') {
                $q['dimensions'] = array_map(function ($dim) {
                    $dim['edit_input'] = $dim['edit_input'] ?? 'radio';
                    $dim['stats'] = self::emptyStats($dim);
                    return $dim;
                }, $q['dimensions'] ?? []);
            }
            $stats[(string) $q['id']] = $q;
        }
        $count = 0;
        foreach ($responses as $response) {
            $count++;
            $map = SurveySchema::answerMap($response['data'] ?? []);
            $snapshot = SurveySchema::arrayValue($response['snapshot'] ?? []);
            $keyed = ($snapshot['version'] ?? 0) >= 2;
            foreach ($stats as $id => &$q) {
                if ($q['edit_input'] === 'section') {
                    continue;
                }
                $raw = $map[$id] ?? [];
                $value = $raw['value'] ?? null;
                if ($q['edit_input'] === 'multi_dimension') {
                    $values = SurveySchema::arrayValue($value);
                    $hasAnswer = false;
                    foreach ($q['dimensions'] as &$dim) {
                        $v = $values[$dim['field']] ?? null;
                        self::add($dim['stats'], $dim, $v, $keyed);
                        $hasAnswer = $hasAnswer || !SurveySchema::blank($v);
                    }
                    unset($dim);
                    if ($hasAnswer) {
                        $q['stats']['valid_count']++;
                    }
                } else {
                    self::add($q['stats'], $q, $value, $keyed);
                }
                if (!SurveySchema::blank($raw['other_text'] ?? $raw['allow_input_text'] ?? null)) {
                    $q['stats']['other_count']++;
                }
            }
            unset($q);
        }
        $scoreSum = 0;
        $scoreCount = 0;
        foreach ($stats as &$q) {
            if ($q['edit_input'] === 'multi_dimension') {
                $q['stats']['score_sum'] = 0;
                $q['stats']['score_count'] = 0;
                foreach ($q['dimensions'] as &$dim) {
                    self::finish($dim['stats']);
                    $q['stats']['score_sum'] += $dim['stats']['score_sum'];
                    $q['stats']['score_count'] += $dim['stats']['score_count'];
                }
                unset($dim);
            }
            self::finish($q['stats']);
            $scoreSum += $q['stats']['score_sum'];
            $scoreCount += $q['stats']['score_count'];
        }
        unset($q);
        return [
            'responses' => $count,
            'questions_count' => count(array_filter($questions, fn ($q) => $q['edit_input'] !== 'section')),
            'average' => $scoreCount ? round($scoreSum / $scoreCount, 2) : null,
            'score_count' => $scoreCount,
            'questions' => array_values($stats),
        ];
    }

    private static function emptyStats(array $field): array
    {
        return [
            'valid_count' => 0, 'other_count' => 0, 'sum' => 0, 'score_sum' => 0, 'score_count' => 0, 'average' => null,
            'options' => array_map(fn ($o) => ['key' => (string) $o['key'], 'label' => $o['value'], 'count' => 0, 'percentage' => 0], $field['select_item'] ?? []),
        ];
    }

    private static function add(array &$stats, array $field, $value, bool $keyed): void
    {
        if (SurveySchema::blank($value)) {
            return;
        }
        $type = $field['edit_input'] ?? 'radio';
        if (in_array($type, ['radio', 'checkbox'], true)) {
            $values = is_array($value) ? $value : ($type === 'checkbox' ? explode(',', (string) $value) : [$value]);
            $matched = false;
            foreach ($field['select_item'] ?? [] as $index => $option) {
                $target = (string) ($keyed ? $option['key'] : $option['value']);
                if (in_array($target, array_map('strval', $values), true)) {
                    $stats['options'][$index]['count']++;
                    $matched = true;
                    if (!empty($field['config']['is_score']) && isset($option['score']) && is_numeric($option['score'])) {
                        $stats['score_count']++;
                        $stats['score_sum'] += (float) $option['score'];
                    }
                }
            }
            if ($matched) {
                $stats['valid_count']++;
            }
        } elseif ($type === 'number') {
            if (is_numeric($value)) {
                $stats['valid_count']++;
                $stats['sum'] += (float) $value;
            }
        } else {
            $stats['valid_count']++;
        }
    }

    private static function finish(array &$stats): void
    {
        $stats['average'] = $stats['score_count'] ? round($stats['score_sum'] / $stats['score_count'], 2) : null;
        foreach ($stats['options'] as &$option) {
            $option['percentage'] = $stats['valid_count'] ? round($option['count'] * 100 / $stats['valid_count'], 1) : 0;
        }
    }
}