const AWS = require('aws-sdk')

AWS.config.update({ region: 'us-east-1' })
const { DynamoDB } = AWS
const dynamoDB = new DynamoDB.DocumentClient()

module.exports.query = function (attributeName, attributeValue, tableName) {
  const params = {
    ExpressionAttributeNames: {
      [`#${attributeName}`]: attributeName
    },
    ExpressionAttributeValues: {
      [`:${attributeName}`]: attributeValue
    },
    // FilterExpression: `#${attributeName} = :${attributeName}`,
    KeyConditionExpression: `#${attributeName} = :${attributeName}`,
    TableName: tableName
  }
  return dynamoDB.query(params).promise()
}

module.exports.getItem = function (attributeName, attributeValue, tableName) {
  const params = {
    TableName: tableName,
    Key: { [attributeName]: attributeValue }
  }

  return dynamoDB.get(params).promise()
}

module.exports.putItem = function (item, tableName) {
  console.log('table', process.env.DYNAMODB_TABLE)
  const params = {
    TableName: tableName,
    Item: item
  }
  return dynamoDB.put(params).promise()
}

module.exports.updateItem = function (keyAttribute, keyValue, attrsToUpdate, attrValues, tableName) {
  const expressionAttributeNames = attrsToUpdate.map((attrToUpdate) => {
    return { [`#${attrToUpdate}`]: attrToUpdate }
  }).reduce((accum, item) => ({ ...accum, ...item }), {})

  const expressionAttributeValues = attrsToUpdate.map((attrToUpdate, index) => {
    return { [`:${attrToUpdate}`]: attrValues[index] }
  }).reduce((accum, item) => ({ ...accum, ...item }), {})
  console.log('attrNames', expressionAttributeNames)
  console.log('attrValues', expressionAttributeValues)

  const updateExpression = attrsToUpdate.map((attrToUpdate) => `#${attrToUpdate} = :${attrToUpdate}`).join(', ')
  const params = {
    TableName: tableName,
    Key: {
      [keyAttribute]: keyValue
    },
    UpdateExpression: 'set ' + updateExpression,
    ExpressionAttributeNames: expressionAttributeNames,
    ExpressionAttributeValues: expressionAttributeValues
  }
  return dynamoDB.update(params).promise()
}

module.exports.deleteItem = function (attributeName, attributeValue, tableName) {
  const params = {
    TableName: tableName,
    Key: {
      [attributeName]: attributeValue
    }
  }
  return dynamoDB.delete(params).promise()
}

module.exports.scan = function (keys, values, tableName, filterExpression) {
  const expressionAttributeNames = keys.map((attrToUpdate) => {
    return { [`#${attrToUpdate}`]: attrToUpdate }
  }).reduce((accum, item) => ({ ...accum, ...item }), {})

  const expressionAttributeValues = keys.map((attrToUpdate, index) => {
    return { [`:${attrToUpdate}`]: values[index] }
  }).reduce((accum, item) => ({ ...accum, ...item }), {})
  console.log('attrNames', expressionAttributeNames)
  console.log('attrValues', expressionAttributeValues)

  let _filterExpression = keys.map((attrToUpdate) => `#${attrToUpdate} = :${attrToUpdate}`).join(' AND ')
  _filterExpression = filterExpression ? `${_filterExpression} AND ${filterExpression}` : _filterExpression

  const params = {
    ExpressionAttributeNames: expressionAttributeNames,
    ExpressionAttributeValues: expressionAttributeValues,
    TableName: tableName,
    FilterExpression: _filterExpression
  }

  return dynamoDB.scan(params).promise()
}

module.exports.appendToList = function (attributeName, attributeValue, keyToUpdate, jsonVals = [], tableName) {
  const params = {
    TableName: tableName,
    Key: {
      [attributeName]: attributeValue
    },
    UpdateExpression: 'SET #c = list_append(#c, :vals)',
    ExpressionAttributeNames: {
      '#c': keyToUpdate
    },
    ExpressionAttributeValues: {
      ':vals': jsonVals
    },
    ReturnValues: 'UPDATED_NEW'
  }

  return dynamoDB.update(params).promise()
}

module.exports.updateItemInList = function (attributeName, attributeValue, keyToUpdate, listItemIndex, value, tableName) {
  const params = {
    TableName: tableName,
    Key: {
      [attributeName]: attributeValue
    },
    UpdateExpression: `SET #item[${listItemIndex}] = :value`,
    ExpressionAttributeNames: {
      '#item': keyToUpdate
    },
    ExpressionAttributeValues: {
      ':value': value
    },
    ReturnValues: 'UPDATED_NEW'
  }

  return dynamoDB.update(params).promise()
}

module.exports.deleteItemFromList = function (attributeName, attributeValue, keyToUpdate, listItemIndex, tableName) {
  console.log('EXPRESSION', `REMOVE #item[${listItemIndex}]`)
  const params = {
    TableName: tableName,
    ExpressionAttributeNames: {
      '#item': keyToUpdate
    },
    Key: {
      [attributeName]: attributeValue
    },
    UpdateExpression: `REMOVE #item[${listItemIndex}]`,
    ReturnValues: 'ALL_NEW'
  }

  return dynamoDB.update(params).promise()
}