<?php

namespace App\Services\Finance;

use App\Enums\EmployeeAdvanceStatus;
use App\Enums\PayrollAdjustmentType;
use App\Enums\PayrollPeriodStatus;
use App\Enums\PayrollStatus;
use App\Enums\Role;
use App\Models\Employee;
use App\Models\EmployeeAdvance;
use App\Models\Payroll;
use App\Models\PayrollPeriod;
use App\Models\User;
use Carbon\Carbon;
use Illuminate\Contracts\Pagination\LengthAwarePaginator;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Support\Collection;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\ValidationException;

class PayrollService
{
    public function __construct(
        private readonly CashService $cashService,
    ) {}

    /**
     * @return Collection<int, PayrollPeriod>
     */
    public function listPeriods(): Collection
    {
        return PayrollPeriod::query()
            ->orderByDesc('year')
            ->orderByDesc('month')
            ->get();
    }

    public function resolvePeriod(?int $periodId): ?PayrollPeriod
    {
        if ($periodId !== null) {
            return PayrollPeriod::query()->find($periodId);
        }

        return PayrollPeriod::query()
            ->where('status', PayrollPeriodStatus::OPEN)
            ->orderByDesc('year')
            ->orderByDesc('month')
            ->first()
            ?? PayrollPeriod::query()
                ->orderByDesc('year')
                ->orderByDesc('month')
                ->first();
    }

    /**
     * @return array{total_net_amount: int, total_net_amount_formatted: string, unpaid_count: int, paid_count: int}
     */
    public function periodSummary(PayrollPeriod $period): array
    {
        $totalNetAmount = (int) Payroll::query()
            ->where('payroll_period_id', $period->id)
            ->where('status', PayrollStatus::UNPAID)
            ->sum('net_amount');

        $unpaidCount = Payroll::query()
            ->where('payroll_period_id', $period->id)
            ->where('status', PayrollStatus::UNPAID)
            ->count();

        $paidCount = Payroll::query()
            ->where('payroll_period_id', $period->id)
            ->where('status', PayrollStatus::PAID)
            ->count();

        return [
            'total_net_amount' => $totalNetAmount,
            'total_net_amount_formatted' => 'Rp '.number_format($totalNetAmount, 0, ',', '.'),
            'unpaid_count' => $unpaidCount,
            'paid_count' => $paidCount,
        ];
    }

    /**
     * @param  array{search: string, sort: string, direction: 'asc'|'desc'}  $tableQuery
     */
    public function paginateForPeriod(PayrollPeriod $period, array $tableQuery): LengthAwarePaginator
    {
        $query = Payroll::query()
            ->with(['employee.user.profile', 'payrollPeriod'])
            ->where('payroll_period_id', $period->id)
            ->when($tableQuery['search'] !== '', function (Builder $query) use ($tableQuery): void {
                $search = $tableQuery['search'];
                $query->where(function (Builder $query) use ($search): void {
                    $query->whereHas('employee.user.profile', fn (Builder $query) => $query->where('full_name', 'like', "%{$search}%"))
                        ->orWhereHas('employee.user', fn (Builder $query) => $query->where('username', 'like', "%{$search}%"));
                });
            });

        $this->applySorting($query, $tableQuery['sort'], $tableQuery['direction']);

        return $query
            ->paginate(10)
            ->withQueryString();
    }

    public function openCurrentPeriod(?User $closedBy = null): PayrollPeriod
    {
        return DB::transaction(function () use ($closedBy): PayrollPeriod {
            $now = now();
            $year = $now->year;
            $month = $now->month;

            PayrollPeriod::query()
                ->where('status', PayrollPeriodStatus::OPEN)
                ->update([
                    'status' => PayrollPeriodStatus::CLOSED,
                    'closed_at' => now(),
                    'closed_by_id' => $closedBy?->id,
                ]);

            $period = PayrollPeriod::query()
                ->where('year', $year)
                ->where('month', $month)
                ->first();

            if ($period === null) {
                $period = PayrollPeriod::create([
                    'year' => $year,
                    'month' => $month,
                    'status' => PayrollPeriodStatus::OPEN,
                ]);
            } elseif ($period->status === PayrollPeriodStatus::CLOSED) {
                $period->status = PayrollPeriodStatus::OPEN;
                $period->closed_at = null;
                $period->closed_by_id = null;
                $period->save();
            }

            $this->generatePayrollsForPeriod($period);

            return $period->fresh();
        });
    }

    public function closePeriod(PayrollPeriod $period, User $user): void
    {
        if (! $period->isOpen()) {
            throw ValidationException::withMessages([
                'payroll_period' => 'Periode gaji ini sudah ditutup.',
            ]);
        }

        $unpaidCount = Payroll::query()
            ->where('payroll_period_id', $period->id)
            ->where('status', PayrollStatus::UNPAID)
            ->where('net_amount', '>', 0)
            ->count();

        if ($unpaidCount > 0) {
            throw ValidationException::withMessages([
                'payroll_period' => 'Masih ada gaji yang belum dibayar.',
            ]);
        }

        $period->status = PayrollPeriodStatus::CLOSED;
        $period->closed_at = now();
        $period->closed_by_id = $user->id;
        $period->save();
    }

    public function generatePayrollsForPeriod(PayrollPeriod $period): void
    {
        $employees = $this->payrollEligibleEmployees($period);

        foreach ($employees as $employee) {
            $exists = Payroll::query()
                ->where('payroll_period_id', $period->id)
                ->where('employee_id', $employee->id)
                ->exists();

            if ($exists) {
                continue;
            }

            $payroll = new Payroll([
                'payroll_period_id' => $period->id,
                'employee_id' => $employee->id,
                'base_salary' => $employee->base_salary,
                'bonus_amount' => 0,
                'deduction_amount' => 0,
                'net_amount' => 0,
                'status' => PayrollStatus::UNPAID,
            ]);

            $payroll->save();
            $payroll->recalculateAmounts();
            $payroll->save();
        }
    }

    /**
     * @param  array{type: string, amount: int, description: string}  $validated
     */
    public function addAdjustment(Payroll $payroll, array $validated, User $user): void
    {
        $payroll->loadMissing('payrollPeriod');

        if (! $payroll->can_adjust) {
            throw ValidationException::withMessages([
                'payroll' => 'Penyesuaian hanya dapat ditambahkan pada gaji yang belum dibayar di periode terbuka.',
            ]);
        }

        DB::transaction(function () use ($payroll, $validated, $user): void {
            $payroll->adjustments()->create([
                'type' => PayrollAdjustmentType::from($validated['type']),
                'amount' => (int) $validated['amount'],
                'description' => $validated['description'],
                'created_by_id' => $user->id,
            ]);

            $payroll->load('adjustments');
            $payroll->recalculateAmounts();
            $payroll->save();
        });
    }

    public function pay(Payroll $payroll, User $user): void
    {
        $payroll->loadMissing(['payrollPeriod', 'employee.user.profile']);

        if ($payroll->status !== PayrollStatus::UNPAID) {
            throw ValidationException::withMessages([
                'payroll' => 'Gaji ini sudah dibayar.',
            ]);
        }

        if (! $payroll->payrollPeriod?->isOpen()) {
            throw ValidationException::withMessages([
                'payroll' => 'Periode gaji sudah ditutup.',
            ]);
        }

        if ($payroll->net_amount <= 0) {
            DB::transaction(function () use ($payroll, $user): void {
                $payroll->status = PayrollStatus::PAID;
                $payroll->paid_at = now();
                $payroll->paid_by_id = $user->id;
                $payroll->save();

                $this->settleKasbonFromPayroll($payroll, $user);
            });

            return;
        }

        DB::transaction(function () use ($payroll, $user): void {
            $description = sprintf(
                'Pembayaran gaji: %s (%s)',
                $payroll->employeeName,
                $payroll->payrollPeriod->period_label,
            );

            $cashTransaction = $this->cashService->recordOutgoing(
                $payroll,
                $payroll->net_amount,
                $description,
                $user,
            );

            $payroll->cash_transaction_id = $cashTransaction->id;
            $payroll->status = PayrollStatus::PAID;
            $payroll->paid_at = now();
            $payroll->paid_by_id = $user->id;
            $payroll->save();

            $this->settleKasbonFromPayroll($payroll, $user);
        });
    }

    /**
     * @return Collection<int, Employee>
     */
    private function payrollEligibleEmployees(PayrollPeriod $period): Collection
    {
        $periodStart = Carbon::create($period->year, $period->month, 1)->startOfMonth();

        return Employee::query()
            ->with('user.roles')
            ->whereHas('user', function (Builder $query): void {
                $query->where('is_active', true)
                    ->whereDoesntHave('roles', fn (Builder $query) => $query->whereIn('name', [
                        Role::DEVELOPER->value,
                        Role::OWNER->value,
                    ]));
            })
            ->where(function (Builder $query) use ($periodStart): void {
                $query->whereNull('resign_date')
                    ->orWhere('resign_date', '>=', $periodStart);
            })
            ->get();
    }

    private function settleKasbonFromPayroll(Payroll $payroll, User $user): void
    {
        $remaining = (int) $payroll->deduction_amount;

        if ($remaining <= 0) {
            return;
        }

        $advances = EmployeeAdvance::query()
            ->where('employee_id', $payroll->employee_id)
            ->where('status', EmployeeAdvanceStatus::APPROVED)
            ->orderBy('created_at')
            ->get();

        foreach ($advances as $advance) {
            if ($remaining <= 0) {
                break;
            }

            $advance->paid_at = now();
            $advance->paid_by_id = $user->id;
            $advance->status = EmployeeAdvanceStatus::PAID;
            $advance->save();

            $remaining -= $advance->amount;
        }
    }

    private function applySorting(Builder $query, string $sort, string $direction): void
    {
        if (in_array($sort, ['base_salary', 'bonus_amount', 'deduction_amount', 'net_amount', 'status', 'created_at'], true)) {
            $query->orderBy($sort, $direction);

            return;
        }

        $query->orderBy('employee_id');
    }
}