import * as plugins from './plugins.js';
import { Account } from './skr.classes.account.js';
import { Transaction } from './skr.classes.transaction.js';
import { JournalEntry } from './skr.classes.journalentry.js';
import type {
  TSKRType,
  ITransactionData,
  IJournalEntry,
  IJournalEntryLine,
  IAccountBalance,
} from './skr.types.js';

export class Ledger {
  private logger: plugins.smartlog.Smartlog;

  constructor(private skrType: TSKRType) {
    this.logger = new plugins.smartlog.Smartlog({
      logContext: {
        company: 'fin.cx',
        companyunit: 'skr',
        containerName: 'Ledger',
        environment: 'local',
        runtime: 'node',
        zone: 'local',
      },
    });
  }

  /**
   * Post a transaction with validation
   */
  public async postTransaction(
    transactionData: ITransactionData,
  ): Promise<Transaction> {
    this.logger.log(
      'info',
      `Posting transaction: ${transactionData.description}`,
    );

    // Ensure SKR type matches
    const fullTransactionData: ITransactionData = {
      ...transactionData,
      skrType: this.skrType,
    };

    // Validate accounts exist
    await this.validateAccounts([
      transactionData.debitAccount,
      transactionData.creditAccount,
    ]);

    // Create and post transaction
    const transaction =
      await Transaction.createTransaction(fullTransactionData);

    this.logger.log(
      'info',
      `Transaction ${transaction.transactionNumber} posted successfully`,
    );
    return transaction;
  }

  /**
   * Post a journal entry with validation
   */
  public async postJournalEntry(
    journalData: IJournalEntry,
  ): Promise<JournalEntry> {
    this.logger.log(
      'info',
      `Posting journal entry: ${journalData.description}`,
    );

    // Ensure SKR type matches
    const fullJournalData: IJournalEntry = {
      ...journalData,
      skrType: this.skrType,
    };

    // Validate all accounts exist
    const accountNumbers = journalData.lines.map((line) => line.accountNumber);
    await this.validateAccounts(accountNumbers);

    // Validate journal entry is balanced
    this.validateJournalBalance(journalData.lines);

    // Create and post journal entry
    const journalEntry = await JournalEntry.createJournalEntry(fullJournalData);
    await journalEntry.post();

    this.logger.log(
      'info',
      `Journal entry ${journalEntry.journalNumber} posted successfully`,
    );
    return journalEntry;
  }

  /**
   * Validate that accounts exist and are active
   */
  private async validateAccounts(accountNumbers: string[]): Promise<void> {
    const uniqueAccountNumbers = [...new Set(accountNumbers)];

    for (const accountNumber of uniqueAccountNumbers) {
      const account = await Account.getAccountByNumber(
        accountNumber,
        this.skrType,
      );

      if (!account) {
        throw new Error(
          `Account ${accountNumber} not found for ${this.skrType}`,
        );
      }

      if (!account.isActive) {
        throw new Error(`Account ${accountNumber} is not active`);
      }
    }
  }

  /**
   * Validate journal entry balance
   */
  private validateJournalBalance(lines: IJournalEntryLine[]): void {
    let totalDebits = 0;
    let totalCredits = 0;

    for (const line of lines) {
      if (line.debit) totalDebits += line.debit;
      if (line.credit) totalCredits += line.credit;
    }

    const difference = Math.abs(totalDebits - totalCredits);
    if (difference >= 0.01) {
      throw new Error(
        `Journal entry is not balanced. Debits: ${totalDebits}, Credits: ${totalCredits}`,
      );
    }
  }

  /**
   * Reverse a transaction
   */
  public async reverseTransaction(transactionId: string): Promise<Transaction> {
    this.logger.log('info', `Reversing transaction: ${transactionId}`);

    const transaction = await Transaction.getTransactionById(transactionId);
    if (!transaction) {
      throw new Error(`Transaction ${transactionId} not found`);
    }

    if (transaction.skrType !== this.skrType) {
      throw new Error(
        `Transaction ${transactionId} belongs to different SKR type`,
      );
    }

    const reversalTransaction = await transaction.reverseTransaction();

    this.logger.log(
      'info',
      `Transaction reversed: ${reversalTransaction.transactionNumber}`,
    );
    return reversalTransaction;
  }

  /**
   * Reverse a journal entry
   */
  public async reverseJournalEntry(journalId: string): Promise<JournalEntry> {
    this.logger.log('info', `Reversing journal entry: ${journalId}`);

    const journalEntry = await JournalEntry.getInstance({ id: journalId });
    if (!journalEntry) {
      throw new Error(`Journal entry ${journalId} not found`);
    }

    if (journalEntry.skrType !== this.skrType) {
      throw new Error(
        `Journal entry ${journalId} belongs to different SKR type`,
      );
    }

    const reversalEntry = await journalEntry.reverse();

    this.logger.log(
      'info',
      `Journal entry reversed: ${reversalEntry.journalNumber}`,
    );
    return reversalEntry;
  }

  /**
   * Get account history (all transactions for an account)
   */
  public async getAccountHistory(
    accountNumber: string,
    dateFrom?: Date,
    dateTo?: Date,
  ): Promise<Transaction[]> {
    const account = await Account.getAccountByNumber(
      accountNumber,
      this.skrType,
    );
    if (!account) {
      throw new Error(`Account ${accountNumber} not found`);
    }

    let transactions = await Transaction.getTransactionsByAccount(
      accountNumber,
      this.skrType,
    );

    // Apply date filter if provided
    if (dateFrom || dateTo) {
      transactions = transactions.filter((transaction) => {
        if (dateFrom && transaction.date < dateFrom) return false;
        if (dateTo && transaction.date > dateTo) return false;
        return true;
      });
    }

    // Sort by date
    transactions.sort((a, b) => a.date.getTime() - b.date.getTime());

    return transactions;
  }

  /**
   * Get account balance at a specific date
   */
  public async getAccountBalance(
    accountNumber: string,
    asOfDate?: Date,
  ): Promise<IAccountBalance> {
    const account = await Account.getAccountByNumber(
      accountNumber,
      this.skrType,
    );
    if (!account) {
      throw new Error(`Account ${accountNumber} not found`);
    }

    let transactions = await Transaction.getTransactionsByAccount(
      accountNumber,
      this.skrType,
    );

    // Filter transactions up to the specified date
    if (asOfDate) {
      transactions = transactions.filter((t) => t.date <= asOfDate);
    }

    // Calculate balance
    let debitTotal = 0;
    let creditTotal = 0;

    for (const transaction of transactions) {
      if (transaction.debitAccount === accountNumber) {
        debitTotal += transaction.amount;
      }
      if (transaction.creditAccount === accountNumber) {
        creditTotal += transaction.amount;
      }
    }

    // Calculate net balance based on account type
    let balance: number;
    switch (account.accountType) {
      case 'asset':
      case 'expense':
        // Normal debit accounts
        balance = debitTotal - creditTotal;
        break;
      case 'liability':
      case 'equity':
      case 'revenue':
        // Normal credit accounts
        balance = creditTotal - debitTotal;
        break;
    }

    return {
      accountNumber,
      debitTotal,
      creditTotal,
      balance,
      lastUpdated: new Date(),
    };
  }

  /**
   * Close accounting period (create closing entries)
   */
  public async closeAccountingPeriod(
    period: string, // Format: YYYY-MM
    closingAccountNumber: string = '9400', // Default P&L account
  ): Promise<JournalEntry[]> {
    this.logger.log('info', `Closing accounting period: ${period}`);

    const closingEntries: JournalEntry[] = [];

    // Get all revenue and expense accounts
    const revenueAccounts = await Account.getAccountsByType(
      'revenue',
      this.skrType,
    );
    const expenseAccounts = await Account.getAccountsByType(
      'expense',
      this.skrType,
    );

    // Calculate totals for each account in the period
    const periodTransactions = await Transaction.getTransactionsByPeriod(
      period,
      this.skrType,
    );

    // Create closing entry for revenue accounts
    const revenueLines: IJournalEntryLine[] = [];
    let totalRevenue = 0;

    for (const account of revenueAccounts) {
      const balance = await this.getAccountBalanceForPeriod(
        account.accountNumber,
        periodTransactions,
      );

      if (balance !== 0) {
        // Revenue accounts have credit balance, so debit to close
        revenueLines.push({
          accountNumber: account.accountNumber,
          debit: Math.abs(balance),
          description: `Closing ${account.accountName}`,
        });
        totalRevenue += Math.abs(balance);
      }
    }

    if (totalRevenue > 0) {
      // Credit the closing account
      revenueLines.push({
        accountNumber: closingAccountNumber,
        credit: totalRevenue,
        description: 'Revenue closing to P&L',
      });

      const revenueClosingEntry = await this.postJournalEntry({
        date: new Date(),
        description: `Closing revenue accounts for period ${period}`,
        reference: `CLOSE-REV-${period}`,
        lines: revenueLines,
        skrType: this.skrType,
      });

      closingEntries.push(revenueClosingEntry);
    }

    // Create closing entry for expense accounts
    const expenseLines: IJournalEntryLine[] = [];
    let totalExpense = 0;

    for (const account of expenseAccounts) {
      const balance = await this.getAccountBalanceForPeriod(
        account.accountNumber,
        periodTransactions,
      );

      if (balance !== 0) {
        // Expense accounts have debit balance, so credit to close
        expenseLines.push({
          accountNumber: account.accountNumber,
          credit: Math.abs(balance),
          description: `Closing ${account.accountName}`,
        });
        totalExpense += Math.abs(balance);
      }
    }

    if (totalExpense > 0) {
      // Debit the closing account
      expenseLines.push({
        accountNumber: closingAccountNumber,
        debit: totalExpense,
        description: 'Expense closing to P&L',
      });

      const expenseClosingEntry = await this.postJournalEntry({
        date: new Date(),
        description: `Closing expense accounts for period ${period}`,
        reference: `CLOSE-EXP-${period}`,
        lines: expenseLines,
        skrType: this.skrType,
      });

      closingEntries.push(expenseClosingEntry);
    }

    this.logger.log(
      'info',
      `Period ${period} closed with ${closingEntries.length} entries`,
    );
    return closingEntries;
  }

  /**
   * Calculate account balance for a specific set of transactions
   */
  private async getAccountBalanceForPeriod(
    accountNumber: string,
    transactions: Transaction[],
  ): Promise<number> {
    const account = await Account.getAccountByNumber(
      accountNumber,
      this.skrType,
    );
    if (!account) return 0;

    let debitTotal = 0;
    let creditTotal = 0;

    for (const transaction of transactions) {
      if (transaction.debitAccount === accountNumber) {
        debitTotal += transaction.amount;
      }
      if (transaction.creditAccount === accountNumber) {
        creditTotal += transaction.amount;
      }
    }

    // Calculate net balance based on account type
    switch (account.accountType) {
      case 'asset':
      case 'expense':
        return debitTotal - creditTotal;
      case 'liability':
      case 'equity':
      case 'revenue':
        return creditTotal - debitTotal;
    }
  }

  /**
   * Validate double-entry rules
   */
  public validateDoubleEntry(
    debitAmount: number,
    creditAmount: number,
  ): boolean {
    return Math.abs(debitAmount - creditAmount) < 0.01;
  }

  /**
   * Get unbalanced transactions (for audit)
   */
  public async getUnbalancedTransactions(): Promise<Transaction[]> {
    // In a proper double-entry system, all posted transactions should be balanced
    // This method is mainly for audit purposes
    const allTransactions = await Transaction.getInstances({
      skrType: this.skrType,
      status: 'posted',
    });

    // Group transactions by journal entry if they have one
    const unbalanced: Transaction[] = [];

    // Since our system ensures balance at posting time,
    // this should typically return an empty array
    // But we include it for completeness and audit purposes

    return unbalanced;
  }

  /**
   * Recalculate all account balances
   */
  public async recalculateAllBalances(): Promise<void> {
    this.logger.log('info', 'Recalculating all account balances');

    // Get all accounts
    const accounts = await Account.getInstances({ skrType: this.skrType });

    for (const account of accounts) {
      // Reset balances
      account.debitTotal = 0;
      account.creditTotal = 0;
      account.balance = 0;

      // Get all transactions for this account
      const transactions = await Transaction.getTransactionsByAccount(
        account.accountNumber,
        this.skrType,
      );

      // Recalculate totals
      for (const transaction of transactions) {
        if (transaction.debitAccount === account.accountNumber) {
          account.debitTotal += transaction.amount;
        }
        if (transaction.creditAccount === account.accountNumber) {
          account.creditTotal += transaction.amount;
        }
      }

      // Calculate balance based on account type
      switch (account.accountType) {
        case 'asset':
        case 'expense':
          account.balance = account.debitTotal - account.creditTotal;
          break;
        case 'liability':
        case 'equity':
        case 'revenue':
          account.balance = account.creditTotal - account.debitTotal;
          break;
      }

      account.updatedAt = new Date();
      await account.save();
    }

    this.logger.log(
      'info',
      `Recalculated balances for ${accounts.length} accounts`,
    );
  }
}