<?php

namespace App\Services;

use Illuminate\Support\Facades\DB;

class IncomeStatementService extends Service
{
    // 손익계산서 항목 구조 (한국 일반기업회계기준, KIS 표준 계정과목 sub_category 매핑)
    private const PL_STRUCTURE = [
        ['code' => 'I', 'name' => '매출액', 'type' => 'sum', 'category' => 'revenue', 'sub_categories' => ['sales_revenue']],
        ['code' => 'II', 'name' => '매출원가', 'type' => 'sum', 'category' => 'expense', 'sub_categories' => ['cogs', 'construction_cost']],
        ['code' => 'III', 'name' => '매출총이익', 'type' => 'calc', 'formula' => 'I - II'],
        ['code' => 'IV', 'name' => '판매비와관리비', 'type' => 'sum', 'category' => 'expense', 'sub_categories' => ['selling_admin']],
        ['code' => 'V', 'name' => '영업이익', 'type' => 'calc', 'formula' => 'III - IV'],
        ['code' => 'VI', 'name' => '영업외수익', 'type' => 'sum', 'category' => 'revenue', 'sub_categories' => ['other_revenue']],
        ['code' => 'VII', 'name' => '영업외비용', 'type' => 'sum', 'category' => 'expense', 'sub_categories' => ['other_expense'], 'exclude_codes' => ['99800', '99900']],
        ['code' => 'VIII', 'name' => '법인세비용차감전순이익', 'type' => 'calc', 'formula' => 'V + VI - VII'],
        ['code' => 'IX', 'name' => '법인세비용', 'type' => 'sum', 'category' => 'expense', 'tax_codes' => ['99800', '99900']],
        ['code' => 'X', 'name' => '당기순이익', 'type' => 'calc', 'formula' => 'VIII - IX'],
    ];

    /**
     * 손익계산서 조회 (기간)
     */
    public function data(array $params): array
    {
        $tenantId = $this->tenantId();
        $startDate = $params['start_date'];
        $endDate = $params['end_date'];
        $unit = $params['unit'] ?? 'won';

        $prevStartDate = date('Y-m-d', strtotime($startDate.' -1 year'));
        $prevEndDate = date('Y-m-d', strtotime($endDate.' -1 year'));

        $accountCodes = $this->getAccountCodes($tenantId);
        $currentSums = $this->getAccountSums($tenantId, $startDate, $endDate);
        $previousSums = $this->getAccountSums($tenantId, $prevStartDate, $prevEndDate);
        $sections = $this->buildSections($accountCodes, $currentSums, $previousSums, $unit);

        $currentYear = (int) date('Y', strtotime($endDate));
        $fiscalYear = $this->getFiscalYear($currentYear);

        return [
            'period' => [
                'current' => ['start' => $startDate, 'end' => $endDate, 'label' => "제 {$fiscalYear} (당)기"],
                'previous' => ['start' => $prevStartDate, 'end' => $prevEndDate, 'label' => '제 '.($fiscalYear - 1).' (전)기'],
            ],
            'unit' => $unit,
            'sections' => $sections,
        ];
    }

    /**
     * 손익계산서 월별 조회
     */
    public function monthly(array $params): array
    {
        $tenantId = $this->tenantId();
        $year = (int) ($params['year'] ?? now()->year);
        $unit = $params['unit'] ?? 'won';

        $accountCodes = $this->getAccountCodes($tenantId);
        $months = [];

        for ($m = 1; $m <= 12; $m++) {
            $startDate = sprintf('%04d-%02d-01', $year, $m);
            $endDate = date('Y-m-t', strtotime($startDate));

            if (strtotime($startDate) > time()) {
                break;
            }

            $sums = $this->getAccountSums($tenantId, $startDate, $endDate);
            $sections = $this->buildSections($accountCodes, $sums, $sums, $unit, true);

            $months[] = [
                'month' => sprintf('%02d', $m),
                'label' => $m.'월',
                'sections' => $sections,
            ];
        }

        $fiscalYear = $this->getFiscalYear($year);

        return [
            'year' => $year,
            'fiscal_year' => $fiscalYear,
            'fiscal_label' => "제 {$fiscalYear} 기",
            'unit' => $unit,
            'months' => $months,
        ];
    }

    private function getAccountCodes(int $tenantId)
    {
        return DB::table('account_codes')
            ->where('tenant_id', $tenantId)
            ->where('is_active', true)
            ->whereIn('category', ['revenue', 'expense'])
            ->orderBy('sort_order')
            ->orderBy('code')
            ->get();
    }

    private function getFiscalYear(int $currentYear): int
    {
        return $currentYear - 2024; // 코드브릿지엑스 설립 2025-09-13, 1기 = 2025년
    }

    /**
     * 섹션 조립 공통 로직
     */
    private function buildSections($accountCodes, array $currentSums, array $previousSums, string $unit, bool $currentOnly = false): array
    {
        $sections = [];
        $calcValues = [];

        foreach (self::PL_STRUCTURE as $item) {
            $section = [
                'code' => $item['code'],
                'name' => $item['name'],
                'current_amount' => 0,
                'previous_amount' => 0,
                'items' => [],
                'is_calculated' => $item['type'] === 'calc',
            ];

            if ($item['type'] === 'sum') {
                $relatedAccounts = $accountCodes->filter(function ($ac) use ($item) {
                    if (! empty($item['tax_codes'])) {
                        return in_array($ac->code, $item['tax_codes']);
                    }
                    $subCategories = $item['sub_categories'] ?? [];
                    if ($ac->category !== $item['category'] || ! in_array($ac->sub_category, $subCategories)) {
                        return false;
                    }
                    if (! empty($item['exclude_codes']) && in_array($ac->code, $item['exclude_codes'])) {
                        return false;
                    }

                    return true;
                });

                $currentTotal = 0;
                $previousTotal = 0;

                foreach ($relatedAccounts as $ac) {
                    $curDebit = $currentSums[$ac->code]['debit'] ?? 0;
                    $curCredit = $currentSums[$ac->code]['credit'] ?? 0;
                    $curAmount = $ac->category === 'revenue' ? ($curCredit - $curDebit) : ($curDebit - $curCredit);

                    $prevAmount = 0;
                    if (! $currentOnly) {
                        $prevDebit = $previousSums[$ac->code]['debit'] ?? 0;
                        $prevCredit = $previousSums[$ac->code]['credit'] ?? 0;
                        $prevAmount = $ac->category === 'revenue' ? ($prevCredit - $prevDebit) : ($prevDebit - $prevCredit);
                    }

                    if ($curAmount != 0 || $prevAmount != 0) {
                        $section['items'][] = ['code' => $ac->code, 'name' => $ac->name, 'current' => $curAmount, 'previous' => $prevAmount];
                    }

                    $currentTotal += $curAmount;
                    $previousTotal += $prevAmount;
                }

                $section['current_amount'] = $currentTotal;
                $section['previous_amount'] = $previousTotal;
                $calcValues[$item['code']] = ['current' => $currentTotal, 'previous' => $previousTotal];
            } elseif ($item['type'] === 'calc') {
                $amounts = $this->evaluateFormula($item['formula'], $calcValues);
                $section['current_amount'] = $amounts['current'];
                $section['previous_amount'] = $amounts['previous'];
                $calcValues[$item['code']] = $amounts;
            }

            $sections[] = $section;
        }

        $divisor = match ($unit) {
            'thousand' => 1000, 'million' => 1000000, default => 1
        };
        if ($divisor > 1) {
            foreach ($sections as &$s) {
                $s['current_amount'] = (int) round($s['current_amount'] / $divisor);
                $s['previous_amount'] = (int) round($s['previous_amount'] / $divisor);
                foreach ($s['items'] as &$it) {
                    $it['current'] = (int) round($it['current'] / $divisor);
                    $it['previous'] = (int) round($it['previous'] / $divisor);
                }
                unset($it);
            }
            unset($s);
        }

        return $sections;
    }

    private function getAccountSums(int $tenantId, string $startDate, string $endDate): array
    {
        $journalSums = DB::table('journal_entry_lines as jel')
            ->join('journal_entries as je', 'je.id', '=', 'jel.journal_entry_id')
            ->where('jel.tenant_id', $tenantId)
            ->whereBetween('je.entry_date', [$startDate, $endDate])
            ->whereNull('je.deleted_at')
            ->groupBy('jel.account_code')
            ->select(['jel.account_code', DB::raw('SUM(jel.debit_amount) as debit'), DB::raw('SUM(jel.credit_amount) as credit')])
            ->get();

        $hometaxSums = DB::table('hometax_invoice_journals as hij')
            ->join('hometax_invoices as hi', 'hi.id', '=', 'hij.hometax_invoice_id')
            ->where('hij.tenant_id', $tenantId)
            ->whereBetween('hij.write_date', [$startDate, $endDate])
            ->whereNull('hi.deleted_at')
            ->groupBy('hij.account_code')
            ->select(['hij.account_code', DB::raw('SUM(hij.debit_amount) as debit'), DB::raw('SUM(hij.credit_amount) as credit')])
            ->get();

        $result = [];
        foreach ($journalSums as $row) {
            $result[$row->account_code] = ['debit' => (int) $row->debit, 'credit' => (int) $row->credit];
        }
        foreach ($hometaxSums as $row) {
            if (! isset($result[$row->account_code])) {
                $result[$row->account_code] = ['debit' => 0, 'credit' => 0];
            }
            $result[$row->account_code]['debit'] += (int) $row->debit;
            $result[$row->account_code]['credit'] += (int) $row->credit;
        }

        return $result;
    }

    private function evaluateFormula(string $formula, array $values): array
    {
        $current = 0;
        $previous = 0;
        $parts = preg_split('/\s*([+-])\s*/', $formula, -1, PREG_SPLIT_DELIM_CAPTURE);
        $sign = 1;

        foreach ($parts as $part) {
            $part = trim($part);
            if ($part === '+') {
                $sign = 1;
            } elseif ($part === '-') {
                $sign = -1;
            } elseif (isset($values[$part])) {
                $current += $sign * $values[$part]['current'];
                $previous += $sign * $values[$part]['previous'];
                $sign = 1;
            }
        }

        return compact('current', 'previous');
    }
}