sana23ok / licensereader

License Reader

The purpose of this task is to practice with reading, processing and writing to a file using Java *Reader/*Writer classes and their buffered variants, and using try-with-resources.

Duration: 1.5 hours

Description

In this task you will implement LicenseReader#collectLicenses(File, File) method. It must read all license files from root, format these licenses to a specific format and write all of them into outputFile. root might be a directory or just a regular file. Please note that you need to collect files not only from the root directory, but also from its subdirectories and their subdirectories, etc. All non-license files must be ignored. Be aware, that this method must not throw any checked exception.

Take a look at the license header format:

---
License: <license name>
Issued by: <issuer>
Issued on: <date>
Expires on: <date>
---

The order of these properties is not restricted, so you may expect that Expires on might occur earlier than License. All of them are mandatory except for Expires on. The date format is ISO date (yyyy-mm-dd). The license is wrapped between lines containing 3 dashes (---). The file always starts with license header, otherwise it's just a regular file.

If license header is invalid, then IllegalArgumentException must be thrown. If either root or outputFile is null, then IllegalArgumentException must be thrown. If root does not exist, or it's not readable, then the same exception must be thrown. And if root is a directory, but is not executable (means that it could not be entered), then IllegalArgumentException must be thrown.

The output format for just one license looks like:

License for <file name> is <license name> issued by <issuer> [<issuedOn date> - <expiresOn date>]

Each line must contain the information about license in this format. If license does not have an expiration date, then instead of <expiresOn date> - unlimited must be used.

If outputFile exists, then it must be cleared. So no appending is allowed.

Requirements

• collectLicenses method must verify that root is:
  • not null
  • exists
  • readable
  • if it's a directory, then that it's executable
• collectLicenses method must verify that outputFile is not null
• if outputFile is not empty, then it must be cleared before writing to it
• all files and directories of root must be processed
• non-license files must be ignored
• license files must be processed and info about it must be stored in outputFile (see formats in Description section)
• if license format is invalid, or any verification is failed, then IllegalArgumentException must be thrown
• all license properties are mandatory, except for Expires on (it's optional)
• the order of license properties are undefined
• the order in the resulting file does not matter
• if Expires on is omitted, then in unlimited must be used
• collectLicenses does not throw any checked exception
• BufferedWriter/BufferedReader must be used for IO operations
• All IO buffered streams must be defined using try-with-resources syntax

Examples

libA/libraryA.lic

---
License: GNU
Issued by: GNU Commitet
Issued on: 2020-01-01
Expires on: 2025-01-01
---

Library description...

libraryB.lic

---
License: Custom
Issued by: Goverment
Issued on: 1984-04-13
---

Top secret info...

output

License for libA/libraryA.lic is GNU issued by GNU Commitet [2020-01-01 - 2025-01-01]
License for libraryB.lic is Custom issued by Goverment [1984-04-13 - unlimited]