<?php

namespace App\Modules\Courses\Application;

use App\Modules\Courses\Domain\CourseVersion;

final class CourseVersionComparison
{
    /** @return array<string, mixed> */
    public function compare(CourseVersion $before, CourseVersion $after): array
    {
        $before->loadMissing(['modules.lessons.blocks', 'assessments.questions']);
        $after->loadMissing(['modules.lessons.blocks', 'assessments.questions']);

        $categories = [
            $this->category('structure', 'ساختار', $this->structure($before), $this->structure($after), $this->structureLabel($before), $this->structureLabel($after)),
            $this->category('content', 'محتوا', $this->content($before), $this->content($after), $this->contentLabel($before), $this->contentLabel($after)),
            $this->category('assessments', 'ارزیابی‌ها', $this->assessments($before), $this->assessments($after), $this->assessmentLabel($before), $this->assessmentLabel($after)),
            $this->category('settings', 'تنظیمات', $this->settings($before), $this->settings($after), 'مشخصات و قوانین نسخه', 'مشخصات و قوانین نسخه'),
        ];

        return [
            'compatible' => true,
            'before' => $this->identity($before),
            'after' => $this->identity($after),
            'changedCategories' => collect($categories)->where('changed', true)->count(),
            'categories' => $categories,
        ];
    }

    public function unpublishedChangeCount(CourseVersion $version): int
    {
        if ($version->status->value !== 'draft') {
            return 0;
        }
        if (! $version->source_version_id) {
            $version->loadMissing(['modules.lessons.blocks', 'assessments.questions']);

            return $version->modules->count() + $version->lessons->count() + $version->blocks->count() + $version->assessments->count();
        }
        $source = CourseVersion::query()->where('organization_id', $version->organization_id)->where('course_id', $version->course_id)->find($version->source_version_id);
        if (! $source) {
            return 0;
        }

        return collect($this->compare($source, $version)['categories'])->where('changed', true)->count();
    }

    /** @return array<string, mixed> */
    private function identity(CourseVersion $version): array
    {
        return ['id' => $version->getKey(), 'number' => $version->version_number, 'status' => $version->status->value];
    }

    /** @return array<string, mixed> */
    private function category(string $key, string $label, array $before, array $after, string $beforeLabel, string $afterLabel): array
    {
        return compact('key', 'label', 'beforeLabel', 'afterLabel') + ['changed' => $before !== $after];
    }

    private function structure(CourseVersion $version): array
    {
        return $version->modules->sortBy('position')->map(fn ($module) => [
            'title' => $module->title,
            'position' => $module->position,
            'lessons' => $module->lessons->sortBy('position')->map(fn ($lesson) => ['title' => $lesson->title, 'position' => $lesson->position, 'presentationMode' => $lesson->presentation_mode])->values()->all(),
        ])->values()->all();
    }

    private function content(CourseVersion $version): array
    {
        return $version->modules->sortBy('position')->flatMap(fn ($module) => $module->lessons->sortBy('position')->map(fn ($lesson) => [
            'lessonPosition' => $lesson->position,
            'blocks' => $lesson->blocks->sortBy('position')->map(fn ($block) => ['type' => $block->type, 'schemaVersion' => $block->schema_version, 'data' => $block->data, 'style' => $block->style, 'behavior' => $block->behavior, 'responsive' => $block->responsive, 'accessibility' => $block->accessibility, 'position' => $block->position])->values()->all(),
        ]))->values()->all();
    }

    private function assessments(CourseVersion $version): array
    {
        return $version->assessments->sortBy('created_at')->map(fn ($assessment) => [
            'title' => $assessment->title,
            'settings' => $assessment->settings,
            'questions' => $assessment->questions->sortBy('position')->map(fn ($question) => ['type' => $question->type, 'prompt' => $question->prompt, 'configuration' => $question->configuration, 'position' => $question->position])->values()->all(),
        ])->values()->all();
    }

    private function settings(CourseVersion $version): array
    {
        return ['title' => $version->title, 'description' => $version->description, 'settings' => $version->settings, 'completionRules' => $version->completion_rules];
    }

    private function structureLabel(CourseVersion $version): string
    {
        return $version->modules->count().' ماژول · '.$version->lessons->count().' درس';
    }

    private function contentLabel(CourseVersion $version): string
    {
        return $version->blocks->count().' بلوک محتوایی';
    }

    private function assessmentLabel(CourseVersion $version): string
    {
        return $version->assessments->count().' ارزیابی';
    }
}