<?php

namespace App\Http\Controllers;

use App\Models\Account;
use App\Models\Expense;
use App\Models\Staff;
use App\Models\Branch;
use App\Models\BranchDocument;
use Illuminate\Http\Request;
use Carbon\Carbon;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Auth;

class ReportController extends Controller
{
    public function getProfitReport(Request $request)
    {
        $user = Auth::guard('web')->user() ?? Auth::guard('receptionist')->user();
        if (!$user) return response()->json(['message' => 'Unauthenticated'], 401);
        
        $branchId = $user->isReceptionist() ? $user->branch_id : $request->query('branch_id');
        $startDate = $request->query('start_date');
        $endDate = $request->query('end_date');
        $page = $request->query('page', 1);
        $perPage = $request->query('per_page', 10);

        // Base Query from Account table (Ledger)
        $query = Account::query()->with('accountable');
        
        if ($branchId) {
            $query->where('branch_id', $branchId);
        }
        if ($startDate) {
            $query->where('date', '>=', $startDate);
        }
        if ($endDate) {
            $query->where('date', '<=', $endDate);
        }

        // Stats from the same filtered query
        $totalCredits = (clone $query)->sum('credit');
        $totalDebits = (clone $query)->sum('debit');
        
        // Fetch Paginated Transactions from the same filtered query
        $allTransactions = $query->where(function($q) {
                $q->where('credit', '>', 0)->orWhere('debit', '>', 0);
            })
            ->orderBy('date', 'desc')
            ->orderBy('time', 'desc')
            ->orderBy('id', 'desc')
            ->get()
            ->map(function($a) {
                $isAdjusted = false;
                $originalAmount = $a->credit > 0 ? $a->credit : $a->debit;
                $remarks = '';

                if ($a->accountable_type === \App\Models\ProductSale::class && $a->accountable) {
                    $originalAmount = $a->accountable->subtotal_amount + $a->accountable->vat_amount;
                    $isAdjusted = abs($a->credit - $originalAmount) > 0.01;
                    $remarks = $a->accountable->remarks;
                } elseif ($a->accountable_type === \App\Models\Collection::class && $a->accountable) {
                    $originalAmount = $a->accountable->items()->sum('subtotal');
                    $isAdjusted = $originalAmount > 0 && abs($a->credit - $originalAmount) > 0.01;
                    $remarks = $a->accountable->remarks;
                }

                return [
                    'id' => $a->id,
                    'date' => $a->date,
                    'time' => $a->time || '00:00:00',
                    'type' => $a->credit > 0 ? 'Income' : 'Expense',
                    'category' => $a->type,
                    'description' => $a->description,
                    'amount' => $a->credit > 0 ? $a->credit : $a->debit,
                    'branch' => 'N/A', // Branch name if needed can be added via relation
                    'is_adjusted' => $isAdjusted,
                    'original_amount' => $originalAmount,
                    'remarks' => $remarks
                ];
            });

        $totalTransactions = $allTransactions->count();
        $paginatedTransactions = $allTransactions->forPage($page, $perPage)->values();
        
        $lowStockCount = \App\Models\Product::query();
        if ($branchId) {
            $lowStockCount->where('branch_id', $branchId);
        }
        $lowStockCount = $lowStockCount->whereRaw('current_stock <= reorder_level')->count();

        // Calculate 6-month trend for Dashboard table/chart
        $trend = [];
        for ($i = 5; $i >= 0; $i--) {
            $monthStart = Carbon::now()->subMonths($i)->startOfMonth();
            $monthEnd = Carbon::now()->subMonths($i)->endOfMonth();
            
            $monthIncome = Account::where('branch_id', $branchId ?: '!=', 0)
                ->when($branchId, fn($q) => $q->where('branch_id', $branchId))
                ->whereBetween('date', [$monthStart->toDateString(), $monthEnd->toDateString()])
                ->sum('credit');
                
            // For trend, we can also use Account table for expenses
            $monthExpense = Account::where('branch_id', $branchId ?: '!=', 0)
                ->when($branchId, fn($q) => $q->where('branch_id', $branchId))
                ->whereBetween('date', [$monthStart->toDateString(), $monthEnd->toDateString()])
                ->sum('debit');
                
            $trend[] = [
                'month' => $monthStart->format('M'),
                'income' => round($monthIncome, 2),
                'expense' => round($monthExpense, 2),
                'profit' => round($monthIncome - $monthExpense, 2),
                'status' => ($monthIncome - $monthExpense) >= 0 ? 'Profit' : 'Loss'
            ];
        }

        return response()->json([
            'total_income' => $totalCredits,
            'total_expense' => $totalDebits,
            'net_profit' => $totalCredits - $totalDebits,
            'low_stock_count' => $lowStockCount,
            'transactions' => $paginatedTransactions,
            'pagination' => [
                'total' => $totalTransactions,
                'per_page' => (int)$perPage,
                'current_page' => (int)$page,
                'last_page' => ceil($totalTransactions / $perPage)
            ],
            'trend' => $trend
        ]);
    }

    public function getExpiryReminders(Request $request)
    {
        $today = Carbon::today();
        $user = Auth::guard('web')->user() ?? Auth::guard('receptionist')->user();
        if (!$user) return response()->json(['message' => 'Unauthenticated'], 401);

        $branchId = $user->isReceptionist() ? $user->branch_id : $request->query('branch_id');
        $startDate = $request->query('start_date');
        $endDate = $request->query('end_date');
        
        $staffDocsQuery = \App\Models\StaffDocument::with('staff.branch')
            ->whereNotNull('expiry_date');
        
        if ($branchId) {
            $staffDocsQuery->whereHas('staff', function($q) use ($branchId) {
                $q->where('branch_id', $branchId);
            });
        }

        if ($startDate) {
            $staffDocsQuery->where('expiry_date', '>=', $startDate);
        }
        if ($endDate) {
            $staffDocsQuery->where('expiry_date', '<=', $endDate);
        }

        $staffDocs = $staffDocsQuery->get()
            ->filter(function($doc) use ($today) {
                $expiryDate = Carbon::parse($doc->expiry_date)->startOfDay();
                $reminderDays = (int)($doc->reminder_days ?? 30);
                return $today->startOfDay()->greaterThanOrEqualTo($expiryDate->copy()->subDays($reminderDays));
            })
            ->map(function($doc) use ($today) {
                $expiryDate = Carbon::parse($doc->expiry_date);
                $reminderDays = (int)($doc->reminder_days ?? 30);
                $reminderStartedOn = $expiryDate->copy()->subDays($reminderDays);

                return [
                    'type' => 'Staff',
                    'entity_name' => $doc->staff->full_name ?? 'N/A',
                    'branch_name' => $doc->staff->branch->name ?? 'Global',
                    'document_name' => $doc->name,
                    'document_number' => $doc->document_number,
                    'reminder_started_on' => $reminderStartedOn->format('d/m/Y'),
                    'expiry_date' => $doc->expiry_date,
                    'days_left' => (int)$today->diffInDays($expiryDate, false)
                ];
            });

        // Branch Document Reminders
        $branchDocsQuery = BranchDocument::with('branch')
            ->whereNotNull('expiry_date');

        if ($branchId) {
            $branchDocsQuery->where('branch_id', $branchId);
        }

        if ($startDate) {
            $branchDocsQuery->where('expiry_date', '>=', $startDate);
        }
        if ($endDate) {
            $branchDocsQuery->where('expiry_date', '<=', $endDate);
        }

        $branchReminders = $branchDocsQuery->get()
            ->filter(function($doc) use ($today) {
                $expiryDate = Carbon::parse($doc->expiry_date);
                $reminderDays = (int)($doc->reminder_days ?? 30);
                return $today->greaterThanOrEqualTo($expiryDate->copy()->subDays($reminderDays));
            })
            ->map(function($doc) use ($today) {
                $expiryDate = Carbon::parse($doc->expiry_date);
                $reminderDays = (int)($doc->reminder_days ?? 30);
                $reminderStartedOn = $expiryDate->copy()->subDays($reminderDays);

                return [
                    'type' => 'Branch',
                    'entity_name' => $doc->branch->name ?? 'N/A',
                    'branch_name' => $doc->branch->name ?? 'Global',
                    'document_name' => $doc->name,
                    'document_number' => $doc->document_number,
                    'reminder_started_on' => $reminderStartedOn->format('d/m/Y'),
                    'expiry_date' => $doc->expiry_date,
                    'days_left' => (int)$today->diffInDays($expiryDate, false)
                ];
            });

        return response()->json([
            'reminders' => $staffDocs->concat($branchReminders)->sortBy('expiry_date')->values()
        ]);
    }

    public function getInvestmentReport(Request $request)
    {
        $user = Auth::guard('web')->user() ?? Auth::guard('receptionist')->user();
        if (!$user) return response()->json(['message' => 'Unauthenticated'], 401);

        $branchId = $user->isReceptionist() ? $user->branch_id : $request->query('branch_id');
        $startDate = $request->query('start_date');
        $endDate = $request->query('end_date');
        
        $query = \App\Models\Investor::with('branches');
        
        if ($branchId) {
            $query->where(function($q) use ($branchId) {
                $q->where('applicable_to_all_branches', true)
                  ->orWhereHas('branches', function($bq) use ($branchId) {
                      $bq->where('branches.id', $branchId);
                  });
            });
        }
        
        if ($startDate) {
            $query->where('investment_date', '>=', $startDate);
        }
        if ($endDate) {
            $query->where('investment_date', '<=', $endDate);
        }
        
        $investors = $query->get();
        $reportData = [];
        $currentMonth = Carbon::now()->startOfMonth();

        $totalInvested = 0;
        $totalROIReturned = 0;

        foreach ($investors as $investor) {
            $investmentDate = Carbon::parse($investor->investment_date)->startOfMonth();
            
            // Get all actual payouts made to this investor
            $totalPaid = \App\Models\InvestorPayout::where('investor_id', $investor->id)->sum('amount');
            $returnsEarned = $totalPaid;
                
            $tempMonth = $investmentDate->copy();
            $periodMonths = 1;
            if ($investor->roi_period === 'Quarterly') $periodMonths = 3;
            if ($investor->roi_period === 'Yearly') $periodMonths = 12;

            $totalPending = 0;
            $carryOver = 0;
            
            // Calculate how much should have been paid up to now
            while ($tempMonth->lessThan($currentMonth)) {
                $monthKey = $tempMonth->format('F Y');
                
                $baseAmount = round($investor->roi_type === 'Percentage'
                    ? ($investor->investment_amount * ($investor->roi_value / 100))
                    : ($investor->roi_value ?? 0), 2);
                    
                $expected = $baseAmount + $carryOver;

                if ($totalPaid >= $expected && $expected > 0) {
                    $totalPaid -= $expected;
                    $carryOver = 0;
                } else {
                    $paidTowardsThis = $totalPaid;
                    $remains = $expected - $paidTowardsThis;
                    $totalPaid = 0;
                    $carryOver = $remains;
                }
                $tempMonth->addMonths($periodMonths);
            }

            $totalPending = $carryOver; // The leftover carryover is the net pending amount
            $totalInvested += $investor->investment_amount;
            $totalROIReturned += $returnsEarned;

            $reportData[] = [
                'investor_id' => $investor->id,
                'investor_name' => $investor->name,
                'investment_date' => $investor->investment_date,
                'investment_amount' => $investor->investment_amount,
                'roi_type' => $investor->roi_type,
                'roi_value' => $investor->roi_value,
                'roi_period' => $investor->roi_period,
                'returns_earned' => $returnsEarned,
                'total_pending' => $totalPending
            ];
        }

        return response()->json([
            'total_invested' => $totalInvested,
            'total_roi_returned' => $totalROIReturned,
            'investors' => collect($reportData)->sortByDesc('investment_date')->values()
        ]);
    }
}