<?php

namespace App\Http\Controllers;

use App\Models\LineItem;
use App\Models\Unit;
use App\Support\ApiDataTransformer;
use Illuminate\Http\Request;

class LineItemController extends Controller
{
    public function index($invoiceId)
    {
        $items = LineItem::with('unit')
            ->select('line_items.*')
            ->where('invoice_id', $invoiceId)
            ->orderBy('position', 'asc')
            ->get();

        return $items->map(function ($item) {
            $itemArray = $item->toArray();

            if ($item->unit) {
                $itemArray['unit_name'] = $item->unit->name;
                $itemArray['unit_symbol'] = $item->unit->symbol;
            }

            return ApiDataTransformer::snakeToCamel($itemArray);
        });
    }

    /**
     * Imports LineItems from a CSV file for a specific invoice
     *
     * CSV Format Requirements:
     * 1. The CSV file must be semicolon-separated (use ; as delimiter) to avoid conflicts with commas in numeric values
     * 2. The CSV file must contain the following columns (in any order):
     *    - position (optional): The position of the item in the invoice (if not provided, items will be numbered sequentially starting from 1)
     *    - title (required): The title of the item
     *    - description (optional): A description of the item
     *    - quantity (optional): The quantity (default: 1). Can use comma as decimal separator and dot as thousands separator (e.g., 1.500,50 for 1500.50)
     *    - unit (required): The unit (must exist in the units table, either as name or symbol)
     *    - price (optional): The price per unit (default: 0). Can use comma as decimal separator and dot as thousands separator (e.g., 1.500,50 for 1500.50)
     *
     * 3. The first row can optionally contain a header row with column names
     * 4. Each row must contain at least the 'title' and 'unit' columns
     * 5. Empty rows or rows with incomplete data will be skipped
     * 6. The CSV file must have the extension .csv or .txt
     *
     * Example CSV (with header):
     * position;title;description;quantity;unit;price
     * 1;"Webdesign";"Development of a new website";10;"Hours";93,75
     * ;"Hosting";"Annual hosting";1.500,50;"lump sum";1.200,00
     *
     * Example CSV (without header):
     * 1;"Webdesign";"Development of a new website";10;"Hours";93,75
     * ;"Hosting";"Annual hosting";1.500,50;"lump sum";1.200,00
     *
     * @param Request $request The HTTP request with the CSV file
     * @return \Illuminate\Http\JsonResponse A JSON response with the imported items or an error message
     */
    public function importFromCsv(Request $request)
    {
        $request->validate([
            'csv' => 'required|file|mimes:csv,txt'
        ]);

        $file = $request->file('csv');
        $csvData = array_map(function ($row) {
            // Use semicolon as delimiter
            return str_getcsv($row, ';');
        }, file($file->getRealPath()));

        // Skip header row if it exists
        if (count($csvData) > 0 && count($csvData[0]) > 0) {
            $headers = array_map('trim', $csvData[0]);
            $data = array_slice($csvData, 1);
        } else {
            $headers = [];
            $data = $csvData;
        }

        // Default headers if none provided
        if (empty($headers)) {
            $headers = ['position', 'title', 'description', 'quantity', 'unit', 'price'];
        }

        $lineItems = [];
        $units = Unit::all();
        $positionCounter = 1;

        // Create a NumberFormatter for German locale
        $formatter = new \NumberFormatter('de_DE', \NumberFormatter::DECIMAL);

        foreach ($data as $row) {
            if (count($row) < count($headers)) {
                continue; // Skip incomplete rows
            }

            $itemData = array_combine($headers, $row);
            $itemData = array_map('trim', $itemData);

            // Validate required fields
            if (empty($itemData['title']) || empty($itemData['unit'])) {
                continue;
            }

            // Find unit by name or symbol
            $unit = $units->first(function ($u) use ($itemData) {
                return strtolower($u->name) === strtolower($itemData['unit']) ||
                    strtolower($u->symbol) === strtolower($itemData['unit']);
            });

            if (!$unit) {
                return response()->json([
                    'message' => "Unit '{$itemData['unit']}' not found in database. Please add it first."
                ], 400);
            }

            // Determine position
            $position = !empty($itemData['position']) ? (float)$itemData['position'] : $positionCounter++;

            // Parse quantity using NumberFormatter
            $quantity = $this->parseNumber($formatter, $itemData['quantity'] ?? 1);

            // Parse price using NumberFormatter
            $price = $this->parseNumber($formatter, $itemData['price'] ?? 0);

            // Validate numeric values
            if (!is_numeric($quantity) || !is_numeric($price)) {
                continue; // Skip rows with invalid numeric values
            }

            $lineItems[] = [
                'id' => 0,
                'invoice_id' => 0,
                'position' => $position,
                'is_section' => false,
                'title' => $itemData['title'],
                'description' => $itemData['description'] ?? '',
                'quantity' => (float)$quantity,
                'unit_id' => $unit->id,
                'unit' => [
                    'id' => $unit->id,
                    'name' => $unit->name,
                    'symbol' => $unit->symbol,
                    'created_at' => $unit->created_at,
                    'updated_at' => $unit->updated_at,
                ],
                'price' => (float)$price,
            ];
        }

        if (empty($lineItems)) {
            return response()->json(['message' => 'No valid items found in the CSV file'], 400);
        }

        return response()->json(
            ApiDataTransformer::snakeToCamel($lineItems)
        );
    }

    /**
     * Parses a number using NumberFormatter for the specified locale
     *
     * @param \NumberFormatter $formatter The NumberFormatter instance
     * @param string|float $value The value to parse
     * @return float The parsed number
     */
    protected function parseNumber(\NumberFormatter $formatter, $value)
    {
        if (is_numeric($value)) {
            return (float)$value;
        }

        if (!is_string($value)) {
            return 0.0;
        }

        // Parse the number using NumberFormatter
        $parsed = $formatter->parse($value);

        // Check if parsing was successful
        if ($parsed === false) {
            return 0.0;
        }

        return (float)$parsed;
    }
}