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Pseudocode summary

Client.js:

  • Import the modules AuthContext from './Authenticate.js', Printer from './Printer.js', Scanner from './Scanner.js'

Define the class Client with:

  • The constructor that takes the parameters: printerEmail, clientId, clientSecret, baseUrl with a default value of 'https://api.epsonconnect.com'

    • If printerEmail is not provided, get it from the environment variables, throw error if not present
    • If clientId is not provided, get it from the environment variables, throw error if not present
    • If clientSecret is not provided, get it from the environment variables, throw error if not present
    • Initialize an instance of AuthContext (authContext) with baseUrl, printerEmail, clientId, clientSecret

  • A method 'initialize' that calls the '_initialize' method of the 'authContext' instance

  • A method 'deauthenticate' that calls the '_deauthenticate' method of the 'authContext' instance

  • A getter 'printer' that creates and returns a new Printer instance using the 'authContext' instance

  • A getter 'scanner' that creates and returns a new Scanner instance using the 'authContext' instance

Define the class ClientError which extends the base Error class:

  • The constructor takes a parameter 'message' and sets its 'name' property to 'ClientError'

Export the classes Client and ClientError

Authenticate.js:

  • Import the axios and moment libraries, and the utility function extractKeyValuePairs from './Utils.js'

Define the class AuthContext with:

  • The constructor that takes the parameters: baseUrl, printerEmail, clientId, clientSecret and initializes several instance variables: baseUrl, printerEmail, clientId, clientSecret, expiresAt, accessToken, refreshToken, and subjectId

  • A private method '_initialize' that calls the '_auth' method

  • A private method '_auth' that:

    • Checks if the current access token expiry time is after the current moment
    • Defines headers and authentication details
    • Prepares a request payload depending on whether an access token already exists or not
    • Sends a POST request to a given endpoint to retrieve an access token
    • If there's an error, it throws an AuthenticationError
    • If it's the first time authenticating, it sets the refresh token
    • Updates the expiry time, access token, and subjectId

  • A private method '_deauthenticate' that sends a DELETE request to a specified endpoint to deauthenticate

  • A method 'send' that:

    • Checks if 'auth' is not provided, if so calls the '_auth' method
    • Defines default headers if 'headers' is not provided
    • Sends an HTTP request with the provided parameters
    • If there's an error in the response, it throws an ApiError
    • Returns the response data

  • A getter 'defaultHeaders' that returns a default headers object with the access token

  • A getter 'deviceId' that returns the subjectId

Define the class AuthenticationError which extends the base Error class:

  • The constructor takes a parameter 'message' and sets its 'name' property to 'AuthenticationError'

Define the class ApiError which extends the base Error class:

  • The constructor takes a parameter 'message' and sets its 'name' property to 'ApiError'

Export the classes AuthContext, AuthenticationError, and ApiError

Printer.js:

Import required modules: URL, URLSearchParams from 'url', fs from 'fs', AuthContext from 'Authenticate.js', and mergeWithDefaultSettings, validateSettings from 'PrinterSettings'.

Define the Printer class with:

  • A constructor that accepts an authContext argument. It throws a PrinterError if the authContext is not an instance of AuthContext. It also initializes the VALID_EXTENSIONS and VALID_OPERATORS sets.

  • A getter method 'deviceId' that retrieves the deviceId from the authContext instance.

  • The method 'capabilities(mode)' which fetches the capabilities of the printer for a specified mode by sending a GET request to a specific endpoint.

  • The method 'printSetting(settings)' that validates and merges provided settings with default settings, sends them to a specific endpoint via a POST request, and adds the settings object to the returned response.

  • The method 'uploadFile(uploadUri, filePath, printMode)' that validates the extension of the file, reads the file content, and sends it to the provided upload URI via a POST request.

  • The method 'executePrint(jobId)' that sends a POST request to execute a print job.

  • The method 'print(filePath, settings = {})' that initiates a print process by calling 'printSetting', 'uploadFile', and 'executePrint' methods sequentially, and finally returns the jobId.

  • The method 'cancelPrint(jobId, operatedBy = 'user')' that validates the operator, checks the job status and if it's cancelable, then sends a POST request to cancel the job.

  • The method 'jobInfo(jobId)' that retrieves information about a specific job by sending a GET request.

  • The method 'info()' that retrieves information about the printer by sending a GET request.

  • The method 'notification(callbackUri, enabled = true)' that sets up notifications by sending a POST request with notification settings.

Define the PrinterError class, which extends the built-in Error class.

Finally, export the Printer and PrinterError classes.

PrinterSettings.js:

  1. Define several Set constants for different printer settings:

    • VALID_PRINT_MODES: contains 'document', 'photo'
    • VALID_MEDIA_SIZES: contains 'ms_a3', 'ms_a4', 'ms_a5', etc.
    • VALID_MEDIA_TYPES: contains 'mt_plainpaper', 'mt_photopaper', 'mt_hagaki', etc.
    • VALID_PRINT_QUALITIES: contains 'high', 'normal', 'draft'
    • VALID_PAPER_SOURCES: contains 'auto', 'rear', 'front1', etc.
    • VALID_COLOR_MODES: contains 'color', 'mono'
    • VALID_TWO_SIDE: contains 'none', 'long', 'short'

  2. Define a function called generateRandomString(length):

    • The function generates a random string of a specified length.

  3. Define a function mergeWithDefaultSettings(settings = {}):

    • The function combines user-supplied print settings with default values.
    • If the user does not supply a certain setting, the function uses a default value.
    • The function returns the combined settings object.

  4. Define a function validateSettings(settings = {}):

    • The function validates the user-supplied settings based on the valid constants defined at the start of the module.
    • If a setting is invalid, the function throws a PrintSettingError.
    • It checks for valid keys, length of job name, print mode, media size, media type, boolean checks for borderless and reverse order, and the rest of the print settings.
    • It has specific checks for print mode with reverse order, and two-sided printing with collation.

  5. Define a class PrintSettingError which extends the built-in JavaScript Error class:

    • The constructor of this class accepts a message parameter.
    • It sets its own name property to 'PrintSettingError'.

  6. The module exports the following: mergeWithDefaultSettings function, validateSettings function, and the PrintSettingError class.

Scanner.js:

  1. Import AuthContext from './Authenticate'

  2. Define a class Scanner with the following methods and properties:

    • constructor(authContext): Takes in an AuthContext object as a parameter. Throws a ScannerError if the provided argument is not an instance of AuthContext. Initializes a _authContext, _path, _destination_cache, and VALID_DESTINATION_TYPES properties on the instance.

    • VALID_DESTINATION_TYPES: A Set that contains 'mail' and 'url' as valid types of scan destinations.

    • list(): An asynchronous method that uses the _authContext to send a 'GET' request to the _path.

    • add(name, destination, type_ = 'mail'): An asynchronous method that adds a new scan destination. It takes name, destination, and type_ as parameters, validates these using the _validateDestination method, prepares a data object, and sends a 'POST' request to _path using _authContext. It then adds the response to the _destination_cache.

    • update(id_, name = null, destination = null, type_ = null): An asynchronous method that updates a scan destination. It retrieves the scan destination from the _destination_cache based on the id_, validates the name, destination, and type_, prepares a data object, and sends a 'POST' request to update the scan destination. It then replaces the updated scan destination in the _destination_cache.

    • remove(id_): An asynchronous method that deletes a scan destination. It sends a 'DELETE' request to the _path and removes the scan destination from the _destination_cache.

    • _validateDestination(name, destination, type_): A private method that validates the name, destination, and type_ parameters according to specific rules. If any of the validations fails, it throws a ScannerError.

  3. Define a class ScannerError that extends the base Error class.

  4. Export the Scanner and ScannerError classes.

Utils.js:

  1. Define a function extractKeyValuePairs(obj, keysToExtract), which extracts key-value pairs from a nested object where the key is in keysToExtract. It takes two arguments, obj and keysToExtract.

    • Create an empty array result to store the final key-value pairs, and a seenObjects WeakSet to avoid circular references.

    • Define a nested function extractPairsRecursive(obj, path = '') that takes obj and path as arguments. This function iterates through each key-value pair of the object:

      • If obj is already in seenObjects, the function returns early to avoid infinite loops due to circular references. Otherwise, it adds obj to seenObjects.

      • It constructs the currentPath by concatenating the path and the key. If path is empty, currentPath equals key.

      • If currentPath is in keysToExtract, it pushes an object with key and value into result.

      • If the value is a non-null object, it recursively calls extractPairsRecursive on value with currentPath.

    • Call extractPairsRecursive on the input obj.

    • After finishing the recursive traversal, return result.

  2. Export the extractKeyValuePairs function.