<?php

namespace App\Filament\Admin\Resources\InternApplications\Widgets;

use App\Models\CareerApplication;
use Filament\Widgets\Widget;
use Carbon\Carbon;

class InternGanttChartWidget extends Widget
{
    protected string $view = 'filament.admin.resources.intern-applications.widgets.intern-gantt-chart-widget';

    protected int | string | array $columnSpan = 'full';

    public function getViewData(): array
    {
        $interns = CareerApplication::query()
            ->where('type', 'internship')
            ->where('status', 'accepted')
            ->whereNotNull('internship_start_date')
            ->whereNotNull('internship_end_date')
            ->orderBy('internship_start_date', 'asc')
            ->get();

        if ($interns->isEmpty()) {
            return [
                'interns' => [],
                'months' => [],
                'totalDays' => 0,
                'minDate' => null,
                'todayPercent' => null,
            ];
        }

        $minDate = Carbon::parse($interns->min('internship_start_date'))->startOfDay();
        $maxDate = Carbon::parse($interns->max('internship_end_date'))->endOfDay();
        
        // Pad the range slightly for better visual presentation
        $minDate = $minDate->copy()->subDays(5);
        $maxDate = $maxDate->copy()->addDays(5);

        $totalDays = $minDate->diffInDays($maxDate);
        if ($totalDays <= 0) {
            $totalDays = 1;
        }

        // Generate months in range
        $months = [];
        $tempDate = $minDate->copy()->startOfMonth();
        $endLimit = $maxDate->copy()->endOfMonth();

        while ($tempDate->lte($endLimit)) {
            $monthStart = $tempDate->copy()->startOfMonth();
            $monthEnd = $tempDate->copy()->endOfMonth();

            $overlapStart = $monthStart->gt($minDate) ? $monthStart : $minDate;
            $overlapEnd = $monthEnd->lt($maxDate) ? $monthEnd : $maxDate;

            if ($overlapStart->lte($overlapEnd)) {
                $daysInOverlap = $overlapStart->diffInDays($overlapEnd) + 1;
                $startOffset = $minDate->diffInDays($overlapStart);
                $months[] = [
                    'name' => $tempDate->translatedFormat('F Y'),
                    'left' => ($startOffset / $totalDays) * 100,
                    'width' => ($daysInOverlap / $totalDays) * 100,
                ];
            }
            $tempDate->addMonth();
        }

        // Calculate today's line position if it falls within the range
        $today = Carbon::today();
        $todayPercent = null;
        if ($today->between($minDate, $maxDate)) {
            $todayPercent = ($minDate->diffInDays($today) / $totalDays) * 100;
        }

        $formattedInterns = $interns->map(function ($intern) use ($minDate, $totalDays) {
            $start = Carbon::parse($intern->internship_start_date)->startOfDay();
            $end = Carbon::parse($intern->internship_end_date)->endOfDay();
            
            $startOffset = $minDate->diffInDays($start);
            $duration = $start->diffInDays($end) + 1;

            $left = ($startOffset / $totalDays) * 100;
            $width = ($duration / $totalDays) * 100;

            // Ensure width is at least a visible sliver
            if ($width < 1.5) {
                $width = 1.5;
            }

            // Assign a stable color palette based on the intern ID
            $palettes = [
                [
                    'bg' => 'bg-emerald-500 dark:bg-emerald-600',
                    'gradient' => 'from-emerald-400 to-teal-500 dark:from-emerald-500 dark:to-teal-600',
                    'text' => 'text-emerald-950 dark:text-emerald-50',
                    'border' => 'border-emerald-500/20',
                    'shadow' => 'shadow-emerald-500/20'
                ],
                [
                    'bg' => 'bg-blue-500 dark:bg-blue-600',
                    'gradient' => 'from-blue-400 to-indigo-500 dark:from-blue-500 dark:to-indigo-600',
                    'text' => 'text-blue-950 dark:text-blue-50',
                    'border' => 'border-blue-500/20',
                    'shadow' => 'shadow-blue-500/20'
                ],
                [
                    'bg' => 'bg-rose-500 dark:bg-rose-600',
                    'gradient' => 'from-rose-400 to-pink-500 dark:from-rose-500 dark:to-pink-600',
                    'text' => 'text-rose-950 dark:text-rose-50',
                    'border' => 'border-rose-500/20',
                    'shadow' => 'shadow-rose-500/20'
                ],
                [
                    'bg' => 'bg-amber-500 dark:bg-amber-600',
                    'gradient' => 'from-amber-400 to-orange-500 dark:from-amber-500 dark:to-orange-600',
                    'text' => 'text-amber-950 dark:text-amber-50',
                    'border' => 'border-amber-500/20',
                    'shadow' => 'shadow-amber-500/20'
                ],
                [
                    'bg' => 'bg-violet-500 dark:bg-violet-600',
                    'gradient' => 'from-violet-400 to-purple-500 dark:from-violet-500 dark:to-purple-600',
                    'text' => 'text-violet-950 dark:text-violet-50',
                    'border' => 'border-violet-500/20',
                    'shadow' => 'shadow-violet-500/20'
                ],
            ];

            $paletteIndex = $intern->id % count($palettes);
            $color = $palettes[$paletteIndex];

            $startMonth = (int) $start->format('n');
            $endMonth = (int) $end->format('n');
            $gridStart = $startMonth + 1;
            $gridEnd = min(14, $endMonth + 2);

            // Background color map based on user's examples
            $hexColors = [
                '#2ecaac', // Emerald Teal
                '#54c6f9', // Sky Blue
                '#ff6252', // Red Coral
                '#f59e0b', // Amber
                '#8b5cf6', // Violet
            ];
            $hexColor = $hexColors[$intern->id % count($hexColors)];
            $isStripes = ($intern->id % 2 === 0);

            return [
                'id' => $intern->id,
                'name' => $intern->name,
                'start_date' => $start->translatedFormat('d M Y'),
                'end_date' => $end->translatedFormat('d M Y'),
                'total_days' => $intern->internship_total_days,
                'left' => $left,
                'width' => $width,
                'color' => $color,
                'grid_start' => $gridStart,
                'grid_end' => $gridEnd,
                'hex_color' => $hexColor,
                'is_stripes' => $isStripes,
                'raw_start' => $intern->internship_start_date,
                'raw_end' => $intern->internship_end_date,
            ];
        });

        return [
            'interns' => $formattedInterns,
            'months' => $months,
            'todayPercent' => $todayPercent,
        ];
    }
}