<?php

namespace App\Http\Controllers\Admin;

use App\Http\Controllers\Controller;
use App\Models\Invoice;
use App\Models\InvoiceItem;
use App\Models\InvoiceInstallment;
use App\Models\InvoiceChargeGroup;
use App\Models\InvoiceChargeGroupItem;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\Storage;
use Mpdf\Mpdf;

class AdminInvoiceController extends Controller
{
    // -------------------------------------------------------------
    // INVOICE LIST PAGE
    // -------------------------------------------------------------
    public function index(Request $request)
    {
        $query = Invoice::with(['items', 'customer', 'container']);

        // Search (जर पुढे form मधून पाठवलंस तर)
        if ($request->filled('search')) {
            $search = $request->search;
            $query->where(function ($q) use ($search) {
                $q->where('invoice_number', 'like', "%{$search}%")
                    ->orWhere('customer_name', 'like', "%{$search}%");
            });
        }

        // Status filter
        if ($request->filled('status') && $request->status !== 'all') {
            $query->where('status', $request->status);
        }

        // Date range filter (invoice_date वर)
        if ($request->filled('start_date')) {
            $query->whereDate('invoice_date', '>=', $request->start_date);
        }

        if ($request->filled('end_date')) {
            $query->whereDate('invoice_date', '<=', $request->end_date);
        }

        // Latest first
        $invoices = $query->latest()->get();

        return view('admin.invoice', compact('invoices'));
    }

    // -------------------------------------------------------------
    // POPUP VIEW (AJAX)
    // -------------------------------------------------------------
    public function popup($id)
    {
        $invoice = Invoice::with([
            'items',
            'customer',
            'container',
            'chargeGroups.items.item',
        ])->findOrFail($id);

        $shipment = null;

        return view('admin.popup_invoice', compact('invoice', 'shipment'));
    }

    // -------------------------------------------------------------
    // EDIT INVOICE PAGE
    // -------------------------------------------------------------
    public function edit($id)
    {
        $invoice = Invoice::with([
            'items',
            'customer',
            'container',
            'chargeGroups.items',
        ])->findOrFail($id);

        $shipment = null;

        $groupedItemIds = $invoice->chargeGroups
            ->flatMap(function ($group) {
                return $group->items->pluck('invoice_item_id');
            })
            ->unique()
            ->values()
            ->toArray();

        return view('admin.invoice_edit', compact('invoice', 'shipment', 'groupedItemIds'));
    }

    // -------------------------------------------------------------
    // UPDATE INVOICE (HEADER LEVEL)
    // -------------------------------------------------------------
    public function update(Request $request, $id)
    {
        Log::info('🟡 Invoice Update Request Received', [
            'invoice_id' => $id,
            'request'    => $request->all(),
        ]);

        $invoice = Invoice::findOrFail($id);

        $data = $request->validate([
            'invoice_date' => 'required|date',
            'due_date'     => 'required|date|after_or_equal:invoice_date',
            'final_amount' => 'required|numeric|min:0',
            'tax_type'     => 'required|in:gst,igst',
            'tax_percent'  => 'required|numeric|min:0|max:28',
            'status'       => 'required|in:pending,paid,overdue',
            'notes'        => 'nullable|string',
        ]);

        Log::info('✅ Validated Invoice Update Data', $data);

        $finalAmount = (float) $data['final_amount'];
        $taxPercent  = (float) $data['tax_percent'];

        if ($data['tax_type'] === 'gst') {
            Log::info('🟢 GST Selected', compact('taxPercent'));

            $data['cgst_percent'] = $taxPercent / 2;
            $data['sgst_percent'] = $taxPercent / 2;
            $data['igst_percent'] = 0;
        } else {
            Log::info('🔵 IGST Selected', compact('taxPercent'));

            $data['cgst_percent'] = 0;
            $data['sgst_percent'] = 0;
            $data['igst_percent'] = $taxPercent;
        }

        $gstAmount = ($finalAmount * $taxPercent) / 100;
        $data['gst_amount']            = $gstAmount;
        $data['final_amount_with_gst'] = $finalAmount + $gstAmount;
        $data['gst_percent']           = $taxPercent;

        Log::info('📌 Final Calculated Invoice Values', [
            'invoice_id'            => $invoice->id,
            'final_amount'          => $finalAmount,
            'gst_amount'            => $data['gst_amount'],
            'final_amount_with_gst' => $data['final_amount_with_gst'],
            'tax_type'              => $data['tax_type'],
            'cgst_percent'          => $data['cgst_percent'],
            'sgst_percent'          => $data['sgst_percent'],
            'igst_percent'          => $data['igst_percent'],
        ]);

        $invoice->update($data);

        Log::info('✅ Invoice Updated Successfully', [
            'invoice_id' => $invoice->id,
        ]);

        $invoice->refresh();
        Log::info('🔍 Invoice AFTER UPDATE (DB values)', [
            'invoice_id'            => $invoice->id,
            'final_amount'          => $invoice->final_amount,
            'gst_percent'           => $invoice->gst_percent,
            'gst_amount'            => $invoice->gst_amount,
            'final_amount_with_gst' => $invoice->final_amount_with_gst,
            'tax_type'              => $invoice->tax_type,
            'cgst_percent'          => $invoice->cgst_percent,
            'sgst_percent'          => $invoice->sgst_percent,
            'igst_percent'          => $invoice->igst_percent,
        ]);

        $this->generateInvoicePDF($invoice);

        return redirect()
            ->route('admin.invoices.index')
            ->with('success', 'Invoice updated & PDF generated successfully.');
    }

    // -------------------------------------------------------------
    // 🔹 UPDATE INVOICE ITEMS (price + ttl_amount)
    // -------------------------------------------------------------
    public function updateItems(Request $request, Invoice $invoice)
    {
        Log::info('🟡 Invoice Items Update Request', [
            'invoice_id' => $invoice->id,
            'payload'    => $request->all(),
        ]);

        $data = $request->validate([
            'items'              => ['required', 'array'],
            'items.*.price'      => ['required', 'numeric', 'min:0'],
            'items.*.ttl_amount' => ['required', 'numeric', 'min:0'],
        ]);

        $itemsInput = $data['items'];

        foreach ($itemsInput as $itemId => $itemData) {
            $item = InvoiceItem::where('id', $itemId)
                ->where('invoice_id', $invoice->id)
                ->first();

            if (!$item) {
                Log::warning('Invoice item not found or mismatched invoice', [
                    'invoice_id' => $invoice->id,
                    'item_id'    => $itemId,
                ]);
                continue;
            }

            $item->price      = $itemData['price'];
            $item->ttl_amount = $itemData['ttl_amount'];
            $item->save();
        }

        $newBaseAmount = InvoiceItem::where('invoice_id', $invoice->id)
            ->sum('ttl_amount');

        $taxType     = $invoice->tax_type;
        $cgstPercent = (float) ($invoice->cgst_percent ?? 0);
        $sgstPercent = (float) ($invoice->sgst_percent ?? 0);
        $igstPercent = (float) ($invoice->igst_percent ?? 0);

        $gstPercent = 0;
        if ($taxType === 'gst') {
            $gstPercent = $cgstPercent + $sgstPercent;
        } elseif ($taxType === 'igst') {
            $gstPercent = $igstPercent;
        }

        $gstAmount    = $newBaseAmount * $gstPercent / 100;
        $finalWithGst = $newBaseAmount + $gstAmount;

        $invoice->final_amount           = $newBaseAmount;
        $invoice->gst_amount             = $gstAmount;
        $invoice->final_amount_with_gst  = $finalWithGst;
        $invoice->gst_percent            = $gstPercent;
        $invoice->save();

        Log::info('✅ Invoice items updated & totals recalculated', [
            'invoice_id'            => $invoice->id,
            'final_amount'          => $invoice->final_amount,
            'gst_amount'            => $invoice->gst_amount,
            'final_amount_with_gst' => $invoice->final_amount_with_gst,
            'tax_type'              => $invoice->tax_type,
            'cgst_percent'          => $invoice->cgst_percent,
            'sgst_percent'          => $invoice->sgst_percent,
            'igst_percent'          => $invoice->igst_percent,
        ]);

        return back()->with('success', 'Invoice items updated successfully.');
    }

    // -------------------------------------------------------------
    // PDF GENERATION USING mPDF
    // -------------------------------------------------------------
    public function generateInvoicePDF($invoice)
    {
        $invoice->load(['items', 'customer', 'container']);
        $shipment = null;

        $fileName = 'invoice-' . $invoice->invoice_number . '.pdf';
        $folder   = public_path('invoices/');

        if (!file_exists($folder)) {
            mkdir($folder, 0777, true);
        }

        $filePath = $folder . $fileName;

        if (file_exists($filePath)) {
            unlink($filePath);
        }

        $mpdf = new Mpdf([
            'mode'         => 'utf-8',
            'format'       => 'A4',
            'default_font' => 'sans-serif',
        ]);

        $html = view('admin.pdf.invoice', [
            'invoice'  => $invoice,
            'shipment' => $shipment,
        ])->render();

        $mpdf->WriteHTML($html);
        $mpdf->Output($filePath, 'F');

        $invoice->update(['pdf_path' => 'invoices/' . $fileName]);
    }

    // -------------------------------------------------------------
    // INSTALLMENTS (ADD)
    // -------------------------------------------------------------
    public function storeInstallment(Request $request, $invoice_id)
    {
        $request->validate([
            'installment_date' => 'required|date',
            'payment_method'   => 'required|string',
            'reference_no'     => 'nullable|string',
            'amount'           => 'required|numeric|min:1',
        ]);

        $invoice   = Invoice::findOrFail($invoice_id);
        $paidTotal = $invoice->installments()->sum('amount');
        $remaining = $invoice->final_amount_with_gst - $paidTotal;

        if ($request->amount > $remaining) {
            return response()->json([
                'status'  => 'error',
                'message' => 'Installment amount exceeds remaining balance.',
            ], 422);
        }

        $installment = InvoiceInstallment::create([
            'invoice_id'       => $invoice_id,
            'installment_date' => $request->installment_date,
            'payment_method'   => $request->payment_method,
            'reference_no'     => $request->reference_no,
            'amount'           => $request->amount,
        ]);

        $newPaid = $paidTotal + $request->amount;

        if ($newPaid >= $invoice->final_amount_with_gst) {
            $invoice->update(['status' => 'paid']);
        }

        return response()->json([
            'status'             => 'success',
            'message'            => 'Installment added successfully.',
            'installment'        => $installment,
            'totalPaid'          => $newPaid,
            'gstAmount'          => $invoice->gst_amount,
            'finalAmountWithGst' => $invoice->final_amount_with_gst,
            'baseAmount'         => $invoice->final_amount,
            'remaining'          => max(0, $invoice->final_amount_with_gst - $newPaid),
            'isCompleted'        => $newPaid >= $invoice->final_amount_with_gst,
        ]);
    }

    // -------------------------------------------------------------
    // INSTALLMENTS (DELETE)
    // -------------------------------------------------------------
    public function deleteInstallment($id)
    {
        $installment = InvoiceInstallment::findOrFail($id);
        $invoice     = $installment->invoice;

        $installment->delete();

        $paidTotal = $invoice->installments()->sum('amount');
        $remaining = $invoice->final_amount_with_gst - $paidTotal;

        if ($remaining > 0 && $invoice->status === 'paid') {
            $invoice->update(['status' => 'pending']);
        }

        return response()->json([
            'status'             => 'success',
            'message'            => 'Installment deleted.',
            'totalPaid'          => $paidTotal,
            'gstAmount'          => $invoice->gst_amount,
            'finalAmountWithGst' => $invoice->final_amount_with_gst,
            'baseAmount'         => $invoice->final_amount,
            'remaining'          => $remaining,
            'isZero'             => $paidTotal == 0,
        ]);
    }

    // -------------------------------------------------------------
    // CHARGE GROUP SAVE (NEW)
    // -------------------------------------------------------------
    public function storeChargeGroup(Request $request, $invoiceId)
    {
        $invoice = Invoice::with('items')->findOrFail($invoiceId);

        $data = $request->validate([
            'group_name'  => 'nullable|string|max:255',
            'basis_type'  => 'required|in:ttl_qty,amount,ttl_cbm,ttl_kg',
            'basis_value' => 'required|numeric',
            'rate'        => 'required|numeric|min:0.0001',
            'auto_total'  => 'required|numeric|min:0.01',
            'item_ids'    => 'required|array',
            'item_ids.*'  => 'integer|exists:invoice_items,id',
        ]);

        $group = InvoiceChargeGroup::create([
            'invoice_id'   => $invoice->id,
            'group_name'   => $data['group_name'] ?? null,
            'basis_type'   => $data['basis_type'],
            'basis_value'  => $data['basis_value'],
            'rate'         => $data['rate'],
            'total_charge' => $data['auto_total'],
        ]);

        foreach ($data['item_ids'] as $itemId) {
            InvoiceChargeGroupItem::create([
                'group_id'        => $group->id,
                'invoice_item_id' => $itemId,
            ]);
        }

        return redirect()
            ->back()
            ->with('success', 'Charge group saved successfully.');
    }

    public function download(Invoice $invoice)
    {
        if (!$invoice->pdf_path || !Storage::exists($invoice->pdf_path)) {
            return back()->with('error', 'PDF not found.');
        }

        return Storage::download($invoice->pdf_path, $invoice->invoice_number . '.pdf');
    }
}