const mongoose = require('mongoose');
const { transactionSchema } = require('@librechat/data-schemas');
const { getBalanceConfig } = require('~/server/services/Config');
const { getMultiplier, getCacheMultiplier } = require('./tx');
const { logger } = require('~/config');
const Balance = require('./Balance');

const cancelRate = 1.15;

/**
 * Updates a user's token balance based on a transaction.
 *
 * @async
 * @function
 * @param {Object} params - The function parameters.
 * @param {string} params.user - The user ID.
 * @param {number} params.incrementValue - The value to increment the balance by (can be negative).
 * @param {import('mongoose').UpdateQuery<import('@librechat/data-schemas').IBalance>['$set']} params.setValues
 * @returns {Promise<Object>} Returns the updated balance response.
 */
const updateBalance = async ({ user, incrementValue, setValues }) => {
  // Use findOneAndUpdate with a conditional update to make the balance update atomic
  // This prevents race conditions when multiple transactions are processed concurrently
  const balanceResponse = await Balance.findOneAndUpdate(
    { user },
    [
      {
        $set: {
          tokenCredits: {
            $cond: {
              if: { $lt: [{ $add: ['$tokenCredits', incrementValue] }, 0] },
              then: 0,
              else: { $add: ['$tokenCredits', incrementValue] },
            },
          },
          ...setValues,
        },
      },
    ],
    { upsert: true, new: true },
  ).lean();

  return balanceResponse;
};

/** Method to calculate and set the tokenValue for a transaction */
transactionSchema.methods.calculateTokenValue = function () {
  if (!this.valueKey || !this.tokenType) {
    this.tokenValue = this.rawAmount;
  }
  const { valueKey, tokenType, model, endpointTokenConfig } = this;
  const multiplier = Math.abs(getMultiplier({ valueKey, tokenType, model, endpointTokenConfig }));
  this.rate = multiplier;
  this.tokenValue = this.rawAmount * multiplier;
  if (this.context && this.tokenType === 'completion' && this.context === 'incomplete') {
    this.tokenValue = Math.ceil(this.tokenValue * cancelRate);
    this.rate *= cancelRate;
  }
};

/**
 * New static method to create an auto-refill transaction that does NOT trigger a balance update.
 * @param {object} txData - Transaction data.
 * @param {string} txData.user - The user ID.
 * @param {string} txData.tokenType - The type of token.
 * @param {string} txData.context - The context of the transaction.
 * @param {number} txData.rawAmount - The raw amount of tokens.
 * @returns {Promise<object>} - The created transaction.
 */
transactionSchema.statics.createAutoRefillTransaction = async function (txData) {
  if (txData.rawAmount != null && isNaN(txData.rawAmount)) {
    return;
  }
  const transaction = new this(txData);
  transaction.endpointTokenConfig = txData.endpointTokenConfig;
  transaction.calculateTokenValue();
  await transaction.save();

  const balanceResponse = await updateBalance({
    user: transaction.user,
    incrementValue: txData.rawAmount,
    setValues: { lastRefill: new Date() },
  });
  const result = {
    rate: transaction.rate,
    user: transaction.user.toString(),
    balance: balanceResponse.tokenCredits,
  };
  logger.debug('[Balance.check] Auto-refill performed', result);
  result.transaction = transaction;
  return result;
};

/**
 * Static method to create a transaction and update the balance
 * @param {txData} txData - Transaction data.
 */
transactionSchema.statics.create = async function (txData) {
  const Transaction = this;
  if (txData.rawAmount != null && isNaN(txData.rawAmount)) {
    return;
  }

  const transaction = new Transaction(txData);
  transaction.endpointTokenConfig = txData.endpointTokenConfig;
  transaction.calculateTokenValue();

  await transaction.save();

  const balance = await getBalanceConfig();
  if (!balance?.enabled) {
    return;
  }

  let incrementValue = transaction.tokenValue;

  const balanceResponse = await updateBalance({
    user: transaction.user,
    incrementValue,
  });

  return {
    rate: transaction.rate,
    user: transaction.user.toString(),
    balance: balanceResponse.tokenCredits,
    [transaction.tokenType]: incrementValue,
  };
};

/**
 * Static method to create a structured transaction and update the balance
 * @param {txData} txData - Transaction data.
 */
transactionSchema.statics.createStructured = async function (txData) {
  const Transaction = this;

  const transaction = new Transaction({
    ...txData,
    endpointTokenConfig: txData.endpointTokenConfig,
  });

  transaction.calculateStructuredTokenValue();

  await transaction.save();

  const balance = await getBalanceConfig();
  if (!balance?.enabled) {
    return;
  }

  let incrementValue = transaction.tokenValue;

  const balanceResponse = await updateBalance({
    user: transaction.user,
    incrementValue,
  });

  return {
    rate: transaction.rate,
    user: transaction.user.toString(),
    balance: balanceResponse.tokenCredits,
    [transaction.tokenType]: incrementValue,
  };
};

/** Method to calculate token value for structured tokens */
transactionSchema.methods.calculateStructuredTokenValue = function () {
  if (!this.tokenType) {
    this.tokenValue = this.rawAmount;
    return;
  }

  const { model, endpointTokenConfig } = this;

  if (this.tokenType === 'prompt') {
    const inputMultiplier = getMultiplier({ tokenType: 'prompt', model, endpointTokenConfig });
    const writeMultiplier =
      getCacheMultiplier({ cacheType: 'write', model, endpointTokenConfig }) ?? inputMultiplier;
    const readMultiplier =
      getCacheMultiplier({ cacheType: 'read', model, endpointTokenConfig }) ?? inputMultiplier;

    this.rateDetail = {
      input: inputMultiplier,
      write: writeMultiplier,
      read: readMultiplier,
    };

    const totalPromptTokens =
      Math.abs(this.inputTokens || 0) +
      Math.abs(this.writeTokens || 0) +
      Math.abs(this.readTokens || 0);

    if (totalPromptTokens > 0) {
      this.rate =
        (Math.abs(inputMultiplier * (this.inputTokens || 0)) +
          Math.abs(writeMultiplier * (this.writeTokens || 0)) +
          Math.abs(readMultiplier * (this.readTokens || 0))) /
        totalPromptTokens;
    } else {
      this.rate = Math.abs(inputMultiplier); // Default to input rate if no tokens
    }

    this.tokenValue = -(
      Math.abs(this.inputTokens || 0) * inputMultiplier +
      Math.abs(this.writeTokens || 0) * writeMultiplier +
      Math.abs(this.readTokens || 0) * readMultiplier
    );

    this.rawAmount = -totalPromptTokens;
  } else if (this.tokenType === 'completion') {
    const multiplier = getMultiplier({ tokenType: this.tokenType, model, endpointTokenConfig });
    this.rate = Math.abs(multiplier);
    this.tokenValue = -Math.abs(this.rawAmount) * multiplier;
    this.rawAmount = -Math.abs(this.rawAmount);
  }

  if (this.context && this.tokenType === 'completion' && this.context === 'incomplete') {
    this.tokenValue = Math.ceil(this.tokenValue * cancelRate);
    this.rate *= cancelRate;
    if (this.rateDetail) {
      this.rateDetail = Object.fromEntries(
        Object.entries(this.rateDetail).map(([k, v]) => [k, v * cancelRate]),
      );
    }
  }
};

const Transaction = mongoose.model('Transaction', transactionSchema);

/**
 * Queries and retrieves transactions based on a given filter.
 * @async
 * @function getTransactions
 * @param {Object} filter - MongoDB filter object to apply when querying transactions.
 * @returns {Promise<Array>} A promise that resolves to an array of matched transactions.
 * @throws {Error} Throws an error if querying the database fails.
 */
async function getTransactions(filter) {
  try {
    return await Transaction.find(filter).lean();
  } catch (error) {
    logger.error('Error querying transactions:', error);
    throw error;
  }
}

module.exports = { Transaction, getTransactions };