== Description
   This is a supplement to the dbi module, allowing you to avoid hard-coding
   passwords in your programs that make database connections. It can also
   be used as a general password storage mechanism for other types of
   connections, e.g. ssh, ftp, etc.

== Requirements
   * sys-admin
   * win32-file (MS Windows only)
   * win32-dir (MS Windows only)
   * win32-process (MS Windows only)

== Installation
   gem install dbi-dbrc

== Synopsis
   require 'dbi/dbrc'
   include DBI

   dbrc = DBRC.new('mydb')

   or

   dbrc = DBRC.new('mydb', 'someUser')

   puts dbrc.db
   puts dbrc.user
   puts dbrc.driver
   puts dbrc.timeout
   puts dbrc.max_reconn
   puts dbrc.interval
   puts dbrc.dsn

== Notes on the .dbrc file
   This module relies on a file in your home directory called ".dbrc", and it
   is meant to be analogous to the ".netrc" file used by programs such as
   telnet. The .dbrc file has several conditions that must be met by the
   module or it will fail:

   * Permissions must be set to 600 (Unix only).
   * Must be hidden (MS Windows only).
   * Must be owned by the current user.
   * Must have database, user and password. Other fields are optional.
   * Must be in the following space-separated format (in the 'plain' version):

   database user password driver timeout maximum_reconnects interval

   e.g. mydb     dan    mypass     oracle   10        2         30

   You may include comments in the .dbrc file by starting the line with a
   "#" symbol.

   A failure in any of the rules mentioned above will result in a DBRC::Error
   being raised. In addition, the file may also be encrypted on MS Windows
   systems, in which case the file will automatically be (temporarily)
   decrypted.

   The format for XML (using the example above) is as follows:

   <dbrc>
      <database name="mydb">
         <user>dan</user>
         <password>mypass</password>
         <driver>oracle</driver>
         <interval>30</interval>
         <timeout>10</timeout>
         <maximum_reconnects>2</maximum_reconnects>
      </database>
   </dbrc>

   The format for YAML is as follows:

   - mydb:
      user: dan
      password: mypass
      driver: oracle
      interval: 30
      timeout: 10
      max_reconn: 2
   
== Constants
VERSION
   The current version of this library, returned as a String.
    
== Class Methods
DBRC.new(db, user=nil, dir=nil)
   The constructor takes one to three arguments. The first argument is the
   database name. This *must* be provided. If only the database name is
   passed, the module will look for the first database entry in the .dbrc
   file that matches.

   The second argument, a user name, is optional. If it is passed, the
   module will look for the first entry in the .dbrc file where both the
   database *and* user name match.

   The third argument, also optional, specifies the directory where DBRC will
   look for the .dbrc file. By default, it looks in the pwuid (present
   working user id) home directory. The rules for a .dbrc file still apply.
    
   MS Windows users should read the "Notes" section for how your home directory
   is determined.
    
== Instance Methods
DBRC#database
   The name of the database. Note that the same entry can appear more than
   once, presumably because you have multiple user id's for the same
   database.
    
DBRC#db
   An alias for DBRC#database.
    
DBRC#database=(database)
   Sets the database to +database+.  This is generally discouraged because
   it does not automatically reset the dsn.
    
DBRC#db=(database)
   An alias for DBRC#database=.
   
DBRC#user
   A valid user name for that database.
    
DBRC#user=(user)
   Sets the user name to +user+.
    
DBRC#password
   The password for that user.
    
DBRC#passwd
   An alias for DBRC#password.
    
DBRC#password=(password)
   Sets the password to +password+.

DBRC#passwd=(password)
   An alias for DBRC#password=.
    
DBRC#driver
   The driver type for that database (Oracle, MySql, etc).
    
DBRC#driver=(driver)
   Sets the driver to +driver+.  This use is discouraged because it does
   not reset the dsn.
    
DBRC#timeout
   The timeout period for a connection before the attempt is dropped.
   
DBRC#time_out
   An alias for DBRC#timeout, provided purely for the sake of backwards
   compatability.
    
DBRC#timeout=(int)
   Sets the timeout value to +int+.
   
DBRC#maximum_reconnects
   The maximum number of reconnect attempts that should be made for the the
   database.  Presumablly, you would use this with a "retry" within a rescue
   block.

DBRC#max_reconn
   An alias for DBRC#maximum_reconnects.
   
DBRC#maximum_reconnects=(max)
   Sets the maximum number of reconnect attempts to +max+.

DBRC#max_reconn=(max)
   An alias for DBRC#maximum_reconnects.
    
DBRC#interval
   The number of seconds to wait before attempting to reconnect to the database
   again should a network/database glitch occur.
    
DBRC#interval=(int)
   Sets the interval seconds between connection attempts.
    
DBRC#dsn
   Returns a string in "dbi:<driver>:<database>" format.
    
DBRC#dsn=(dsn)
   Sets the dsn string to +dsn+.  This method is discouraged because it does
   not automatically reset the driver or database.
    
== Canonical Example
   # This is a basic template for how I do things:

   require 'dbi/dbrc'
   require 'timeout'

   db = DBI::DBRC.new("somedb")
   n = db.max_reconn

   begin
      Timeout.timeout(db.timeout){
         DBI.connect(db.dsn, db.user, db.passwd)
      }
   rescue DBI::Error
      n -= 1
      if n > 0
         sleep db.interval
         retry
      end
      raise
   rescue TimeoutError
      # handle timeout error
   end

== Notes for MS Windows Users
   The 'home' directory for Win32 users is determined by ENV['USERPROFILE'].
   If that is not set, ENV['HOME'] is used. If that is not set, then
   the directory found by the sys-admin library is used.

   To make your file hidden, right click on the .dbrc file in your Explorer
   window, select "Properties" and check the "Hidden" checkbox.

   I was going to require that the .dbrc file be encrypted on MS Windows,
   but that may require an official "certificate", assigned to you by a third
   party, which is a bit much to expect. However, if the file is encrypted,
   DBRC will attempt to decrypt it, parse it, and encrypt it again when done
   parsing.

== Notes on running the test suite
   I cannot guarantee that the .dbrc files under the +examples+
   subdirectories maintain the appropriate properties. This can cause
   failures for the test suite (which uses these files).
   
   The only solution is to perform a 'chmod 600 .dbrc' (on Unix) or set
   the properties to 'hidden' (on MS Windows) manually, for the file in
   question.
   
== Summary
   These "methods" don't really do anything. They're simply meant as a
   convenience mechanism for you dbi connections, plus a little bit of
   obfuscation (for passwords).

== Adding your own configuration
   If you want to add your own type of configuration file, you can still use
   the dbi-dbrc library. All you need to do is:

   * subclass DBRC
   * redefine the +parse_dbrc_config_file+ method (a private method).

   Take a look at the XML and YML subclasses in dbrc.rb for two examples that
   you can work from.
   
== Future Plans
   Add DBI::DBRC::JSON.
   
== Known Bugs
   I'm not positive about the dsn strings for databases other than Oracle.
   If it's not correct, please let me know.
   
== Copyright
   (C) Copyright 2002-2013, Daniel J. Berger, all rights reserved.
   
= Warranty
   This package is provided "as is" and without any express or
   implied warranties, including, without limitation, the implied
   warranties of merchantability and fitness for a particular purpose
   
== Author
   Daniel J. Berger