<?php

namespace App\Services;

use App\Models\FranchiseeAccountReceive;
use App\Models\FranchiseeAccountReceiveDetail;
use App\Models\FranchiseeContract;
use App\Models\InhabitantClassification;
use App\Models\Tbr;
use App\Models\TbrCalculation;
use Carbon\Carbon;
use Illuminate\Pagination\LengthAwarePaginator;
use Illuminate\Support\Facades\Auth;
use Illuminate\Support\Facades\DB;
use Illuminate\Validation\ValidationException;

class TbrCalculationService
{
    private const ROYALTIES_REVENUE_RATE = 0.08;
    private const FNM_REVENUE_RATE       = 0.02;
    private const FNM_BRACKET_PERCENTAGE = 0.20;
    private const MAINTENANCE_RATE       = 0.30;
    private const EXEMPT_THRESHOLD_MONTH = 3;

    public function paginate(int $perPage = 15): LengthAwarePaginator
    {
        return TbrCalculation::with(['unit', 'user'])
            ->orderBy('created_at', 'desc')
            ->paginate($perPage);
    }

    public function listAll(int $limit = 100): \Illuminate\Database\Eloquent\Collection
    {
        return TbrCalculation::with(['unit', 'user'])
            ->orderBy('created_at', 'desc')
            ->limit($limit)
            ->get();
    }

    public function findById(int $id): ?TbrCalculation
    {
        return TbrCalculation::with([
            'unit',
            'user',
            'royaltiesBracket',
        ])->find($id);
    }

    public function preview(array $data): array
    {
        $contract = $this->resolveContract($data['unit_id']);
        return $this->buildPreview($contract, (int) $data['reference_year'], (int) $data['reference_month'], (float) ($data['revenue_value'] ?? 0));
    }

    public function previewBatch(int $referenceYear, int $referenceMonth): array
    {
        $contracts = $this->loadActiveContracts($referenceYear, $referenceMonth);

        return $contracts->map(function (FranchiseeContract $contract) use ($referenceYear, $referenceMonth) {
            try {
                return $this->buildPreview($contract, $referenceYear, $referenceMonth, 0);
            } catch (ValidationException $e) {
                return [
                    'unit_id'   => $contract->unit_id,
                    'unit_name' => $contract->unit?->fantasy_name,
                    'error'     => collect($e->errors())->flatten()->first(),
                ];
            }
        })->values()->toArray();
    }

    public function calculate(array $data): TbrCalculation
    {
        return DB::transaction(function () use ($data) {
            $contract = $this->resolveContract($data['unit_id']);
            $payload  = $this->buildPreview($contract, (int) $data['reference_year'], (int) $data['reference_month'], (float) ($data['revenue_value'] ?? 0));

            return $this->persistCalculation($payload);
        });
    }

    public function generateReceivable(int $calculationId): FranchiseeAccountReceive
    {
        return DB::transaction(function () use ($calculationId) {
            $calculation = TbrCalculation::lockForUpdate()->findOrFail($calculationId);

            if ($calculation->receivable_generated) {
                throw ValidationException::withMessages([
                    'tbr_calculation_id' => 'Já existe um título gerado para este cálculo.',
                ]);
            }

            $duplicate = TbrCalculation::where('unit_id', $calculation->unit_id)
                ->where('contract_month_reference', $calculation->contract_month_reference)
                ->where('receivable_generated', true)
                ->where('id', '!=', $calculation->id)
                ->exists();

            if ($duplicate) {
                throw ValidationException::withMessages([
                    'tbr_calculation_id' => 'Já existe um título gerado para esta unidade no mês de contrato '
                        . $calculation->contract_month_reference . '.',
                ]);
            }

            $contract = FranchiseeContract::where('unit_id', $calculation->unit_id)
                ->orderByDesc('start_date')
                ->first();

            return $this->buildReceivable($calculation, $contract);
        });
    }

    public function generateBatch(int $referenceYear, int $referenceMonth, ?array $unitIds = null): array
    {
        $contracts = $this->loadActiveContracts($referenceYear, $referenceMonth);

        if ($unitIds !== null) {
            $contracts = $contracts->filter(fn ($c) => in_array($c->unit_id, $unitIds, true))->values();
        }

        $generated = [];
        $skipped   = [];
        $errors    = [];

        foreach ($contracts as $contract) {
            try {
                DB::transaction(function () use ($contract, $referenceYear, $referenceMonth, &$generated, &$skipped) {
                    $payload = $this->buildPreview($contract, $referenceYear, $referenceMonth, 0);

                    if ($payload['receivable_already_generated']) {
                        $skipped[] = [
                            'unit_id'   => $contract->unit_id,
                            'unit_name' => $payload['unit_name'],
                            'reason'    => 'Já gerado para este mês de contrato.',
                        ];
                        return;
                    }

                    $calculation = $this->persistCalculation($payload);
                    $receive     = $this->buildReceivable($calculation, $contract);

                    $generated[] = [
                        'unit_id'             => $contract->unit_id,
                        'unit_name'           => $payload['unit_name'],
                        'tbr_calculation_id'  => $calculation->id,
                        'receivable_id'       => $receive->id,
                        'total'               => $payload['final_value'],
                    ];
                });
            } catch (ValidationException $e) {
                $errors[] = [
                    'unit_id'   => $contract->unit_id,
                    'unit_name' => $contract->unit?->fantasy_name,
                    'reason'    => collect($e->errors())->flatten()->first(),
                ];
            } catch (\Throwable $e) {
                $errors[] = [
                    'unit_id'   => $contract->unit_id,
                    'unit_name' => $contract->unit?->fantasy_name,
                    'reason'    => $e->getMessage(),
                ];
            }
        }

        return [
            'generated_count' => count($generated),
            'skipped_count'   => count($skipped),
            'error_count'     => count($errors),
            'generated'       => $generated,
            'skipped'         => $skipped,
            'errors'          => $errors,
        ];
    }

    private function loadActiveContracts(int $referenceYear, int $referenceMonth): \Illuminate\Support\Collection
    {
        $referenceLastDay  = Carbon::createFromDate($referenceYear, $referenceMonth, 1)->endOfMonth()->toDateString();
        $referenceFirstDay = Carbon::createFromDate($referenceYear, $referenceMonth, 1)->startOfMonth()->toDateString();

        return FranchiseeContract::with(['unit', 'municipalitySize'])
            ->whereNotNull('start_date')
            ->whereNotNull('municipality_size_id')
            ->where('start_date', '<=', $referenceLastDay)
            ->where(function ($q) use ($referenceFirstDay) {
                $q->whereNull('end_date')->orWhere('end_date', '>=', $referenceFirstDay);
            })
            ->orderByDesc('start_date')
            ->orderByDesc('id')
            ->get()
            ->unique('unit_id')
            ->values();
    }

    private function resolveContract(int $unitId): FranchiseeContract
    {
        $contract = FranchiseeContract::with(['unit', 'municipalitySize'])
            ->where('unit_id', $unitId)
            ->whereNotNull('start_date')
            ->orderByDesc('start_date')
            ->orderByDesc('id')
            ->first();

        if (!$contract) {
            throw ValidationException::withMessages([
                'unit_id' => 'Unidade não possui contrato cadastrado.',
            ]);
        }

        if (!$contract->municipality_size_id) {
            throw ValidationException::withMessages([
                'unit_id' => 'O contrato da unidade não tem a faixa de habitantes definida. Edite o contrato para informá-la.',
            ]);
        }

        return $contract;
    }

    private function buildPreview(FranchiseeContract $contract, int $referenceYear, int $referenceMonth, float $revenueValue): array
    {
        $tbrValue = (float) ($contract->tbr_fixed_value ?? 0);

        if ($tbrValue <= 0) {
            $tbrValue = (float) (Tbr::where('year', $referenceYear)->orderByDesc('id')->value('tbr_value') ?? 0);
        }

        if ($tbrValue <= 0) {
            throw ValidationException::withMessages([
                'unit_id' => 'TBR não definida para o contrato nem para o ano de referência.',
            ]);
        }

        $contractMonth = $this->resolveContractMonth($contract->start_date, $referenceYear, $referenceMonth);
        $municipalitySizeId = (int) $contract->municipality_size_id;

        $royaltiesBracket  = $this->findRoyaltiesBracket($municipalitySizeId, $contractMonth);
        $fnmPercentage     = $this->resolveFnmPercentage($contractMonth);
        $maintenancePercentage = self::MAINTENANCE_RATE;

        $royaltiesBracketValue   = round((float) $royaltiesBracket->tbr_percentage * $tbrValue, 2);
        $fnmBracketValue         = round($fnmPercentage * $tbrValue, 2);
        $maintenanceBracketValue = round($maintenancePercentage * $tbrValue, 2);

        [$royaltiesEffectiveValue, $royaltiesEffectivePercentage, $royaltiesAppliedCriteria,
         $fnmEffectiveValue, $fnmEffectivePercentage] = $this->resolveEffectiveValues(
            $contractMonth,
            $revenueValue,
            (float) $royaltiesBracket->tbr_percentage,
            $royaltiesBracketValue,
            $fnmPercentage,
            $fnmBracketValue,
        );

        $maintenanceEffectiveValue      = $maintenanceBracketValue;
        $maintenanceEffectivePercentage = $maintenancePercentage;

        $bracketSubtotal = round($royaltiesBracketValue + $fnmBracketValue + $maintenanceBracketValue, 2);
        $subtotal        = round($royaltiesEffectiveValue + $fnmEffectiveValue + $maintenanceEffectiveValue, 2);

        return [
            'unit_id'                          => $contract->unit_id,
            'unit_name'                        => $contract->unit?->fantasy_name,
            'contract_id'                      => $contract->id,
            'reference_year'                   => $referenceYear,
            'reference_month'                  => $referenceMonth,
            'contract_month_reference'         => $contractMonth,
            'revenue_value'                    => $revenueValue,
            'tbr_value'                        => $tbrValue,
            'municipality_size_id'             => $municipalitySizeId,
            'municipality_size_name'           => $contract->municipalitySize?->description,
            'royalties_bracket_id'             => $royaltiesBracket->id,
            'royalties_bracket_percentage'     => (float) $royaltiesBracket->tbr_percentage,
            'royalties_bracket_value'          => $royaltiesBracketValue,
            'fnm_bracket_percentage'           => $fnmPercentage,
            'fnm_bracket_value'                => $fnmBracketValue,
            'maintenance_bracket_percentage'   => $maintenancePercentage,
            'maintenance_bracket_value'        => $maintenanceBracketValue,
            'royalties_effective_percentage'   => $royaltiesEffectivePercentage,
            'royalties_effective_value'        => $royaltiesEffectiveValue,
            'fnm_effective_percentage'         => $fnmEffectivePercentage,
            'fnm_effective_value'              => $fnmEffectiveValue,
            'maintenance_effective_percentage' => $maintenanceEffectivePercentage,
            'maintenance_effective_value'      => $maintenanceEffectiveValue,
            'bracket_subtotal'                 => $bracketSubtotal,
            'subtotal'                         => $subtotal,
            'final_value'                      => $subtotal,
            'royalties_applied_criteria'       => $royaltiesAppliedCriteria,
            'receivable_already_generated'     => $this->existingReceivable($contract->unit_id, $contractMonth),
        ];
    }

    private function persistCalculation(array $payload): TbrCalculation
    {
        return TbrCalculation::create([
            'unit_id'                          => $payload['unit_id'],
            'revenue_value'                    => $payload['revenue_value'],
            'contract_month_reference'         => $payload['contract_month_reference'],
            'tbr_value'                        => $payload['tbr_value'],
            'royalties_bracket_id'             => $payload['royalties_bracket_id'],
            'royalties_bracket_percentage'     => $payload['royalties_bracket_percentage'],
            'royalties_bracket_value'          => $payload['royalties_bracket_value'],
            'fnm_bracket_percentage'           => $payload['fnm_bracket_percentage'],
            'fnm_bracket_value'                => $payload['fnm_bracket_value'],
            'maintenance_bracket_percentage'   => $payload['maintenance_bracket_percentage'],
            'maintenance_bracket_value'        => $payload['maintenance_bracket_value'],
            'royalties_effective_percentage'   => $payload['royalties_effective_percentage'],
            'royalties_effective_value'        => $payload['royalties_effective_value'],
            'fnm_effective_percentage'         => $payload['fnm_effective_percentage'],
            'fnm_effective_value'              => $payload['fnm_effective_value'],
            'maintenance_effective_percentage' => $payload['maintenance_effective_percentage'],
            'maintenance_effective_value'      => $payload['maintenance_effective_value'],
            'bracket_subtotal'                 => $payload['bracket_subtotal'],
            'subtotal'                         => $payload['subtotal'],
            'final_value'                      => $payload['final_value'],
            'user_id'                          => Auth::id(),
            'royalties_applied_criteria'       => $payload['royalties_applied_criteria'],
            'receivable_generated'             => false,
        ]);
    }

    private function buildReceivable(TbrCalculation $calculation, ?FranchiseeContract $contract): FranchiseeAccountReceive
    {
        $referenceDate  = Carbon::parse($calculation->created_at);
        $referenceLabel = $referenceDate->format('m/Y');
        $dueDate        = $this->resolveDueDate($contract, $referenceDate);

        $receive = FranchiseeAccountReceive::create([
            'unit_id'            => $calculation->unit_id,
            'tbr_calculation_id' => $calculation->id,
            'order'              => $calculation->contract_month_reference,
            'history'            => 'Royalties / FNM / Manutenção — ' . $referenceLabel,
            'value'              => $calculation->final_value,
            'paid_value'         => 0,
            'due_date'           => $dueDate,
            'discount'           => 0,
            'fees'               => 0,
            'obs'                => null,
            'asaas_id'           => null,
            'status'             => 'pending',
        ]);

        FranchiseeAccountReceiveDetail::create([
            'franchisee_account_receive_id' => $receive->id,
            'value'                         => $calculation->royalties_effective_value,
            'history'                       => 'Royalties ' . $referenceLabel,
        ]);
        FranchiseeAccountReceiveDetail::create([
            'franchisee_account_receive_id' => $receive->id,
            'value'                         => $calculation->fnm_effective_value,
            'history'                       => 'FNM ' . $referenceLabel,
        ]);
        FranchiseeAccountReceiveDetail::create([
            'franchisee_account_receive_id' => $receive->id,
            'value'                         => $calculation->maintenance_effective_value,
            'history'                       => 'Taxa Manutenção ' . $referenceLabel,
        ]);

        $calculation->update(['receivable_generated' => true]);

        return $receive->load('details');
    }

    private function resolveEffectiveValues(
        int $contractMonth,
        float $revenueValue,
        float $royaltiesBracketPercentage,
        float $royaltiesBracketValue,
        float $fnmBracketPercentage,
        float $fnmBracketValue,
    ): array {
        if ($contractMonth <= self::EXEMPT_THRESHOLD_MONTH) {
            return [0.0, 0.0, 'tbr_fixo', 0.0, 0.0];
        }

        $royaltiesFromRevenue = round(self::ROYALTIES_REVENUE_RATE * $revenueValue, 2);
        $fnmFromRevenue       = round(self::FNM_REVENUE_RATE * $revenueValue, 2);

        if ($royaltiesBracketValue >= $royaltiesFromRevenue) {
            $royaltiesEffectiveValue      = $royaltiesBracketValue;
            $royaltiesEffectivePercentage = $royaltiesBracketPercentage;
            $royaltiesAppliedCriteria     = 'tbr_fixo';
        } else {
            $royaltiesEffectiveValue      = $royaltiesFromRevenue;
            $royaltiesEffectivePercentage = self::ROYALTIES_REVENUE_RATE;
            $royaltiesAppliedCriteria     = 'percentual_faturamento';
        }

        if ($fnmBracketValue >= $fnmFromRevenue) {
            $fnmEffectiveValue      = $fnmBracketValue;
            $fnmEffectivePercentage = $fnmBracketPercentage;
        } else {
            $fnmEffectiveValue      = $fnmFromRevenue;
            $fnmEffectivePercentage = self::FNM_REVENUE_RATE;
        }

        return [$royaltiesEffectiveValue, $royaltiesEffectivePercentage, $royaltiesAppliedCriteria, $fnmEffectiveValue, $fnmEffectivePercentage];
    }

    private function resolveContractMonth(?Carbon $startDate, int $year, int $month): int
    {
        if (!$startDate) {
            return 1;
        }

        $start     = $startDate->copy()->startOfMonth();
        $reference = Carbon::createFromDate($year, $month, 1)->startOfMonth();
        $diff      = (int) $start->diffInMonths($reference);

        return max(1, $diff + 1);
    }

    private function findRoyaltiesBracket(int $municipalitySizeId, int $contractMonth): InhabitantClassification
    {
        $bracket = InhabitantClassification::where('municipality_size_id', $municipalitySizeId)
            ->where('is_renewal', false)
            ->where('start', '<=', $contractMonth)
            ->where(function ($q) use ($contractMonth) {
                $q->whereNull('end')->orWhere('end', '>=', $contractMonth);
            })
            ->orderBy('start')
            ->first();

        if (!$bracket) {
            throw ValidationException::withMessages([
                'municipality_size_id' => 'Não foi encontrada faixa de royalties para o porte e mês de contrato informados.',
            ]);
        }

        return $bracket;
    }

    private function resolveFnmPercentage(int $contractMonth): float
    {
        return $contractMonth <= self::EXEMPT_THRESHOLD_MONTH ? 0.0 : self::FNM_BRACKET_PERCENTAGE;
    }

    private function resolveDueDate(?FranchiseeContract $contract, Carbon $referenceDate): Carbon
    {
        $dueDay = (int) ($contract?->invoice_due_date ?? 10);
        $dueDay = max(1, min(28, $dueDay));

        return $referenceDate->copy()->addMonthNoOverflow()->day($dueDay);
    }

    private function existingReceivable(int $unitId, int $contractMonth): bool
    {
        return TbrCalculation::where('unit_id', $unitId)
            ->where('contract_month_reference', $contractMonth)
            ->where('receivable_generated', true)
            ->exists();
    }
}