<?php

namespace App\Http\Controllers;

use App\Http\Requests\ValidateSelectionRequest;
use App\Models\MasterImage;
use App\Models\Reservation;
use App\Services\SelectionMapper;
use Carbon\Carbon;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Storage;

class PublicGridController extends Controller
{
    public function show()
    {
        $meta = $this->meta();

        return inertia('PublicGrid/Index', [
            'master_image_url' => $meta['master_image_url'],
            'master_version' => $meta['master_version'],
            'cell_size' => $meta['cell_size'],
        ]);
    }

    public function meta(): array
    {
        $masterPath = config('pixel_grid.master_path');
        $url = Storage::disk('public')->url($masterPath);

        $master = MasterImage::latest()->first();

        $version = $master ? $master->version : 1;

        return [
            'master_image_url' => $url.'?v='.$version,
            'master_version' => $version,
            'cell_size' => (int) config('pixel_grid.cell_size'),
        ];
    }

    public function price(): array
    {
        return [
            'price_per_cell' => (int) config('pixel_grid.price_per_cell'),
        ];
    }

    public function availability(): array
    {
        // Stub for MVP — returns empty array
        return [
            'occupied' => [],
        ];
    }

    public function validateSelection(ValidateSelectionRequest $request, SelectionMapper $mapper)
    {
        $data = $request->validated();

        $offsetX = $data['offsetX'] ?? 0;
        $offsetY = $data['offsetY'] ?? 0;

        $cellSize = (int) config('pixel_grid.cell_size', 20);

        $mapped = $mapper->mapPixelsToCells(
            (float) $data['x'],
            (float) $data['y'],
            (float) $data['w'],
            (float) $data['h'],
            (float) $offsetX,
            (float) $offsetY,
            $cellSize
        );

        return response()->json(['selection' => $mapped]);
    }

    public function reserveSelection(ValidateSelectionRequest $request, SelectionMapper $mapper)
    {
        $data = $request->validated();

        $offsetX = $data['offsetX'] ?? 0;
        $offsetY = $data['offsetY'] ?? 0;
        $cellSize = (int) config('pixel_grid.cell_size', 20);

        $mapped = $mapper->mapPixelsToCells(
            (float) $data['x'],
            (float) $data['y'],
            (float) $data['w'],
            (float) $data['h'],
            (float) $offsetX,
            (float) $offsetY,
            $cellSize
        );

        // Hold duration in minutes
        $holdMinutes = (int) config('pixel_grid.hold_minutes', 5);
        $now = Carbon::now();
        $expiresAt = $now->copy()->addMinutes($holdMinutes);

        // Transaction + FOR UPDATE style check for overlapping active reservations
        $result = DB::transaction(function () use ($mapped, $expiresAt, $now) {
            $overlaps = Reservation::where(function ($q) use ($mapped) {
                $q->whereRaw('NOT (x + w <= ? OR x >= ? OR y + h <= ? OR y >= ?)', [
                    $mapped['x'],
                    $mapped['x'] + $mapped['w'],
                    $mapped['y'],
                    $mapped['y'] + $mapped['h'],
                ]);
            })->where(function ($q) use ($now) {
                $q->where('status', 'held')->where('reserved_until', '>', $now)
                    ->orWhere('status', 'confirmed');
            })->lockForUpdate()->exists();

            if ($overlaps) {
                return null;
            }

            $reservation = Reservation::create([
                'x' => $mapped['x'],
                'y' => $mapped['y'],
                'w' => $mapped['w'],
                'h' => $mapped['h'],
                'status' => 'held',
                'reserved_until' => $expiresAt,
            ]);

            return $reservation;
        });

        if (! $result) {
            return response()->json(['message' => 'Selection conflicts with an existing reservation'], 409);
        }

        return response()->json(['reservation_id' => $result->id, 'expires_at' => $result->reserved_until]);
    }

    public function confirmReservation(Request $request)
    {
        $id = $request->input('reservation_id');

        if (! $id) {
            return response()->json(['message' => 'reservation_id required'], 422);
        }

        $now = Carbon::now();

        $reservation = Reservation::where('id', $id)->lockForUpdate()->first();

        if (! $reservation) {
            return response()->json(['message' => 'not_found'], 404);
        }

        if ($reservation->status !== 'held') {
            return response()->json(['message' => 'invalid_status'], 409);
        }

        if ($reservation->reserved_until && $reservation->reserved_until->lessThanOrEqualTo($now)) {
            $reservation->status = 'expired';
            $reservation->save();

            return response()->json(['message' => 'expired'], 409);
        }

        $reservation->status = 'confirmed';
        $reservation->save();

        return response()->json(['reservation_id' => $reservation->id, 'status' => 'confirmed']);
    }
}