<?php

namespace App\Services\ClassProgress;

use App\Models\ClassProgressReport;
use App\Models\TeacherClass;
use App\Models\User;
use Illuminate\Database\Eloquent\Collection;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Log;

class ClassProgressMutationService
{
    public function __construct(
        private ClassProgressRuleService $rules,
        private ClassProgressAttachmentService $attachments
    ) {}

    public function createReports(User $user, array $payload, array $filesBySubject): Collection
    {
        $subjectSections = (array) config('progress.subject_sections', []);
        $classSectionId = (int) ($payload['class_section_id'] ?? 0);

        $this->assertTeacherAssignment($user, $classSectionId);

        $weekStart = (string) ($payload['week_start'] ?? '');
        $weekEnd = $this->rules->ensureWeekEnd($weekStart, $payload['week_end'] ?? null);

        if (!$this->rules->isWeekEndValid($weekStart, $weekEnd)) {
            throw new \InvalidArgumentException('Week end must be the same as or after the week start.');
        }

        $reports = DB::transaction(function () use ($user, $payload, $subjectSections, $classSectionId, $weekStart, $weekEnd, $filesBySubject) {
            $created = collect();

            foreach ($subjectSections as $slug => $section) {
                $covered = trim((string) ($payload["covered_{$slug}"] ?? ''));
                if ($covered === '') {
                    continue;
                }

                $homework = trim((string) ($payload["homework_{$slug}"] ?? ''));
                $unitValues = (array) ($payload["unit_{$slug}"] ?? []);
                $chapterValues = (array) ($payload["chapter_{$slug}"] ?? []);
                $unitTitle = $this->rules->buildUnitChapterSummary($unitValues, $chapterValues);

                $report = ClassProgressReport::query()->create([
                    'teacher_id' => $user->id,
                    'class_section_id' => $classSectionId,
                    'week_start' => $weekStart,
                    'week_end' => $weekEnd,
                    'subject' => $section['db_subject'] ?? $section['label'] ?? $slug,
                    'unit_title' => $unitTitle,
                    'covered' => $covered,
                    'homework' => $homework !== '' ? $homework : null,
                    'status' => $this->rules->defaultStatus(),
                    'support_needed' => $payload['support_needed'] ?? null,
                    'flags_json' => $this->rules->normalizeFlags($payload['flags'] ?? null),
                ]);

                $attachments = $filesBySubject[$slug] ?? [];
                $stored = $this->attachments->storeAttachments($report->id, $attachments);
                if ($stored !== []) {
                    $report->update(['attachment_path' => $stored[0]['file_path'] ?? null]);
                }

                $created->push($report);
            }

            if ($created->isEmpty()) {
                throw new \InvalidArgumentException('Please provide progress for at least one subject.');
            }

            return $created;
        });

        Log::info('Class progress reports created.', [
            'teacher_id' => $user->id,
            'class_section_id' => $classSectionId,
            'count' => $reports->count(),
        ]);

        return $reports;
    }

    public function updateReport(ClassProgressReport $report, array $payload, array $attachments): ClassProgressReport
    {
        return DB::transaction(function () use ($report, $payload, $attachments) {
            $weekStart = $payload['week_start'] ?? $report->week_start?->format('Y-m-d');
            $weekEnd = $this->rules->ensureWeekEnd((string) $weekStart, $payload['week_end'] ?? null);
            if ($weekStart && $weekEnd && !$this->rules->isWeekEndValid((string) $weekStart, (string) $weekEnd)) {
                throw new \InvalidArgumentException('Week end must be the same as or after the week start.');
            }

            $data = [];
            if ($weekStart) {
                $data['week_start'] = $weekStart;
            }
            if ($weekEnd) {
                $data['week_end'] = $weekEnd;
            }
            if (array_key_exists('covered', $payload)) {
                $data['covered'] = $payload['covered'];
            }
            if (array_key_exists('homework', $payload)) {
                $data['homework'] = $payload['homework'];
            }
            if (array_key_exists('unit_title', $payload)) {
                $data['unit_title'] = $payload['unit_title'];
            }
            if (array_key_exists('status', $payload)) {
                $data['status'] = $payload['status'];
            }
            if (array_key_exists('support_needed', $payload)) {
                $data['support_needed'] = $payload['support_needed'];
            }
            if (array_key_exists('flags', $payload)) {
                $data['flags_json'] = $this->rules->normalizeFlags($payload['flags']);
            }

            if ($data !== []) {
                $report->fill($data);
                $report->save();
            }

            if ($attachments !== []) {
                $stored = $this->attachments->storeAttachments($report->id, $attachments);
                if ($stored !== []) {
                    $report->update(['attachment_path' => $stored[0]['file_path'] ?? $report->attachment_path]);
                }
            }

            return $report->fresh(['classSection', 'attachments']);
        });
    }

    public function deleteReport(ClassProgressReport $report): void
    {
        DB::transaction(function () use ($report) {
            $report->attachments()->delete();
            $report->delete();
        });
    }

    private function assertTeacherAssignment(User $user, int $classSectionId): void
    {
        if ($classSectionId <= 0) {
            throw new \InvalidArgumentException('No class assignment found for this report.');
        }

        if ($this->isAdmin($user)) {
            return;
        }

        $assigned = TeacherClass::query()
            ->where('teacher_id', $user->id)
            ->where('class_section_id', $classSectionId)
            ->exists();

        if (!$assigned) {
            throw new \InvalidArgumentException('No class assignment found for this report.');
        }
    }

    private function isAdmin(User $user): bool
    {
        $roles = $user->roles()
            ->pluck('roles.name')
            ->map(fn ($name) => strtolower((string) $name))
            ->toArray();

        foreach (['administrator', 'admin', 'principal', 'vice_principal', 'vice-principal'] as $role) {
            if (in_array($role, $roles, true)) {
                return true;
            }
        }

        return false;
    }
}