<?php

namespace App\Traits;

use App\Models\AccountingEntry;
use App\Models\ChartOfAccount;
use Illuminate\Database\Eloquent\Relations\HasMany;

/**
 * Trait for models that can have accounting entries (double-entry bookkeeping).
 *
 * Usage:
 * 1. Add `use HasAccountingEntries;` to your model
 * 2. Define the `getAccountingDescription()` method in your model
 * 3. Define the `getAccountingDate()` method in your model
 * 4. Define the `getAccountingChartOfAccountId()` method if auto-generating entries
 */
trait HasAccountingEntries
{
    /**
     * Get all accounting entries for this model
     */
    public function accountingEntries(): HasMany
    {
        return $this->hasMany(AccountingEntry::class, $this->getAccountingForeignKey());
    }

    /**
     * Get the foreign key name for accounting entries
     */
    protected function getAccountingForeignKey(): string
    {
        return 'finance_document_id';
    }

    /**
     * Get debit entries for this model
     */
    public function debitEntries(): HasMany
    {
        return $this->accountingEntries()->where('entry_type', AccountingEntry::ENTRY_TYPE_DEBIT);
    }

    /**
     * Get credit entries for this model
     */
    public function creditEntries(): HasMany
    {
        return $this->accountingEntries()->where('entry_type', AccountingEntry::ENTRY_TYPE_CREDIT);
    }

    /**
     * Validate that debit and credit entries balance
     */
    public function validateBalance(): bool
    {
        $debitTotal = $this->debitEntries()->sum('amount');
        $creditTotal = $this->creditEntries()->sum('amount');

        return bccomp((string) $debitTotal, (string) $creditTotal, 2) === 0;
    }

    /**
     * Generate accounting entries for this model
     * This creates the double-entry bookkeeping records
     */
    public function generateAccountingEntries(array $entries): void
    {
        // Delete existing entries
        $this->accountingEntries()->delete();

        // Create new entries
        foreach ($entries as $entry) {
            $this->accountingEntries()->create([
                'chart_of_account_id' => $entry['chart_of_account_id'],
                'entry_type' => $entry['entry_type'],
                'amount' => $entry['amount'],
                'entry_date' => $entry['entry_date'] ?? $this->getAccountingDate(),
                'description' => $entry['description'] ?? $this->getAccountingDescription(),
            ]);
        }
    }

    /**
     * Auto-generate simple accounting entries based on account type
     * For basic income/expense transactions
     */
    public function autoGenerateAccountingEntries(): void
    {
        $chartOfAccountId = $this->getAccountingChartOfAccountId();

        // Only auto-generate if chart_of_account_id is set
        if (! $chartOfAccountId) {
            return;
        }

        $entries = [];
        $entryDate = $this->getAccountingDate();
        $description = $this->getAccountingDescription();
        $amount = $this->getAccountingAmount();

        // Get account to determine type
        $account = ChartOfAccount::find($chartOfAccountId);
        if (! $account) {
            return;
        }

        if ($account->account_type === 'income') {
            // Income: Debit Cash, Credit Income Account
            $entries[] = [
                'chart_of_account_id' => $this->getCashAccountId(),
                'entry_type' => AccountingEntry::ENTRY_TYPE_DEBIT,
                'amount' => $amount,
                'entry_date' => $entryDate,
                'description' => '收入 - '.$description,
            ];
            $entries[] = [
                'chart_of_account_id' => $chartOfAccountId,
                'entry_type' => AccountingEntry::ENTRY_TYPE_CREDIT,
                'amount' => $amount,
                'entry_date' => $entryDate,
                'description' => $description,
            ];
        } elseif ($account->account_type === 'expense') {
            // Expense: Debit Expense Account, Credit Cash
            $entries[] = [
                'chart_of_account_id' => $chartOfAccountId,
                'entry_type' => AccountingEntry::ENTRY_TYPE_DEBIT,
                'amount' => $amount,
                'entry_date' => $entryDate,
                'description' => $description,
            ];
            $entries[] = [
                'chart_of_account_id' => $this->getCashAccountId(),
                'entry_type' => AccountingEntry::ENTRY_TYPE_CREDIT,
                'amount' => $amount,
                'entry_date' => $entryDate,
                'description' => '支出 - '.$description,
            ];
        }

        if (! empty($entries)) {
            $this->generateAccountingEntries($entries);
        }
    }

    /**
     * Get the cash account ID using config
     */
    protected function getCashAccountId(): int
    {
        static $cashAccountId = null;

        if ($cashAccountId === null) {
            $cashCode = config('accounting.account_codes.cash', '1101');
            $cashAccount = ChartOfAccount::where('account_code', $cashCode)->first();
            $cashAccountId = $cashAccount ? $cashAccount->id : 1;
        }

        return $cashAccountId;
    }

    /**
     * Get the bank account ID using config
     */
    protected function getBankAccountId(): int
    {
        static $bankAccountId = null;

        if ($bankAccountId === null) {
            $bankCode = config('accounting.account_codes.bank', '1201');
            $bankAccount = ChartOfAccount::where('account_code', $bankCode)->first();
            $bankAccountId = $bankAccount ? $bankAccount->id : 2;
        }

        return $bankAccountId;
    }

    /**
     * Get description for accounting entries
     * Override in model if needed
     */
    protected function getAccountingDescription(): string
    {
        return $this->description ?? $this->title ?? 'Transaction';
    }

    /**
     * Get date for accounting entries
     * Override in model if needed
     */
    protected function getAccountingDate()
    {
        return $this->submitted_at ?? $this->created_at ?? now();
    }

    /**
     * Get chart of account ID for auto-generation
     * Override in model if needed
     */
    protected function getAccountingChartOfAccountId(): ?int
    {
        return $this->chart_of_account_id ?? null;
    }

    /**
     * Get amount for accounting entries
     * Override in model if needed
     */
    protected function getAccountingAmount(): float
    {
        return (float) ($this->amount ?? 0);
    }
}