<?php

namespace App\Http\Controllers;

use App\Models\Expense;
use App\Models\Category;
use App\Models\CategoryRule;
use Illuminate\Http\Request;

class InvoiceImportController extends Controller
{
    // ── 自動偵測格式 ──
    private function detectFormat(array $firstRow): string
    {
        // AndroMoney 第一行是 "Windows Excel", "理財幫手AndroMoney", 日期
        if (isset($firstRow[1]) && str_contains($firstRow[1], 'AndroMoney')) {
            return 'andromoney';
        }
        return 'invoice';
    }

    // ── 取得或建立分類 ──
    private function findOrCreateCategory(string $name, ?int $parentId = null): int
    {
        $category = Category::firstOrCreate(
            [
                'user_id'   => auth()->id(),
                'name'      => $name,
                'parent_id' => $parentId,
            ],
            [
                'color' => $this->randomColor(),
            ]
        );
        return $category->id;
    }

    private function randomColor(): string
    {
        $colors = [
            '#EF4444',
            '#F59E0B',
            '#10B981',
            '#3B82F6',
            '#8B5CF6',
            '#EC4899',
            '#14B8A6',
            '#F97316',
        ];
        return $colors[array_rand($colors)];
    }

    // ── 發票格式匯入 ──
    private function importInvoice($handle, $rules): array
    {
        $imported = 0;
        $updated  = 0;

        while (($row = fgetcsv($handle)) !== false) {
            if (count($row) < 8) continue;

            $invoiceNumber = trim($row[2] ?? '');
            $date          = trim($row[1] ?? '');
            $amount        = trim($row[3] ?? '0');
            $sellerName    = trim($row[7] ?? '');
            $itemName      = trim($row[13] ?? '');

            if (empty($invoiceNumber)) continue;
            if ((float)$amount < 0) {
                $updated++;
                continue;
            }

            $formattedDate = null;
            if (strlen($date) === 8) {
                $formattedDate = substr($date, 0, 4) . '-'
                    . substr($date, 4, 2) . '-'
                    . substr($date, 6, 2);
            }

            $exists = Expense::where('user_id', auth()->id())
                ->where('invoice_number', $invoiceNumber)
                ->exists();

            if ($exists) {
                $updated++;
                continue;
            }

            $categoryId = $this->guessCategory($sellerName, $rules);

            $expense = Expense::updateOrCreate(
                [
                    'user_id'     => auth()->id(),
                    'external_id' => $invoiceNumber,
                ],
                [
                    'type'           => 'expense',
                    'amount'         => (float)$amount,
                    'date'           => $formattedDate,
                    'seller_name'    => $sellerName,
                    'item_name'      => $itemName,
                    'invoice_number' => $invoiceNumber,
                    'note'           => $sellerName,
                    'category_id'    => $categoryId,
                ]
            );
            if ($expense->wasRecentlyCreated) {
                $imported++;
            } else {
                $updated++;
            }
        }

        return [$imported, $updated];
    }

    // ── AndroMoney 格式匯入 ──
    private function importAndroMoney($handle): array
    {
        $imported = 0;
        $updated  = 0;

        // 跳過標題列（第二行）
        fgetcsv($handle);

        while (($row = fgetcsv($handle)) !== false) {
            // 轉換 Big5 → UTF-8
            $row = array_map(fn($val) => mb_convert_encoding($val, 'UTF-8', 'Big5'), $row);

            if (count($row) < 6) continue;
            // 欄位對應
            // A=0:id, B=1:幣別, C=2:金額, D=3:分類, E=4:子分類
            // F=5:日期, G=6:付款, H=7:收款, I=8:備註, M=12:商家, N=13:uid
            $amount      = trim($row[2]  ?? '0');
            $catName     = trim($row[3]  ?? '');
            $subCatName  = trim($row[4]  ?? '');
            $date        = trim($row[5]  ?? '');
            $payOut      = trim($row[6]  ?? '');
            $payIn       = trim($row[7]  ?? '');
            $note       = trim($row[8]  ?? '');
            $sellerName = trim($row[13] ?? '');

            // 過濾掉看起來像 uid 的值（32碼以上的hex字串）
            if (preg_match('/^[0-9a-f]{20,}$/i', $note)) {
                $note = '';
            }

            if (empty($amount) || empty($date)) continue;
            if ((float)$amount == 0) continue;

            // 日期格式轉換 20260106 → 2026-01-06
            $formattedDate = null;
            if (strlen($date) === 8 && is_numeric($date)) {
                $formattedDate = substr($date, 0, 4) . '-'
                    . substr($date, 4, 2) . '-'
                    . substr($date, 6, 2);
            }

            // 日期無效就跳過
            if (!$formattedDate) {
                $updated++;
                continue;
            }

            // 判斷收入/支出
            // 付款欄有值 = 支出，收款欄有值 = 收入
            $type = !empty($payIn) ? 'income' : 'expense';

            // 取得或建立主分類
            $categoryId = null;
            if (!empty($catName)) {
                $categoryId = $this->findOrCreateCategory($catName);
            }

            // 取得或建立子分類（掛在主分類下）
            $subcategoryId = null;
            if (!empty($subCatName) && $categoryId) {
                $subcategoryId = $this->findOrCreateCategory($subCatName, $categoryId);
            }

            // uid 是 row[12]
            $uid = trim($row[12] ?? '');

            $expense = Expense::updateOrCreate(
                [
                    'user_id'     => auth()->id(),
                    'external_id' => $uid ?: null,
                ],
                [
                    'type'           => $type,
                    'amount'         => abs((float)$amount),
                    'date'           => $formattedDate,
                    'category_id'    => $categoryId,
                    'subcategory_id' => $subcategoryId,
                    'note'           => $note ?: $sellerName,
                    'seller_name'    => $sellerName,
                ]
            );

            if ($expense->wasRecentlyCreated) {
                $imported++;
            } else {
                $updated++;
            }
        }

        return [$imported, $updated];
    }

    // ── 自動分類（發票用）──
    private function guessCategory($sellerName, $rules)
    {
        foreach ($rules as $rule) {
            if (str_contains($sellerName, $rule->keyword)) {
                return $rule->category_id;
            }
        }
        return null;
    }

    public function index()
    {
        return inertia('Expenses/Import');
    }

    public function store(Request $request)
    {
        $request->validate([
            'file' => 'required|file|mimes:csv,txt',
        ]);

        $file   = $request->file('file');
        $handle = fopen($file->getPathname(), 'r');

        // 讀第一行偵測格式
        $firstRow = fgetcsv($handle);
        $format   = $this->detectFormat($firstRow);

        $rules = CategoryRule::with('category')
            ->where('user_id', auth()->id())
            ->get();

        if ($format === 'andromoney') {
            [$imported, $updated] = $this->importAndroMoney($handle);
        } else {
            [$imported, $updated] = $this->importInvoice($handle, $rules);
        }

        fclose($handle);

        $formatName = $format === 'andromoney' ? 'AndroMoney' : '發票';

        return redirect()->route('expenses.index')->with([
            'message' => "【{$formatName}】匯入完成！新增 {$imported} 筆，更新 {$updated} 筆",
        ]);
    }
}