# frozen-string-literal: true

%w'bigdecimal date thread time uri'.each{|f| require f}

# Top level module for Sequel
#
# There are some module methods that are added via metaprogramming, one for
# each supported adapter.  For example:
#
#   DB = Sequel.sqlite # Memory database
#   DB = Sequel.sqlite('blog.db')
#   DB = Sequel.postgres('database_name',
#          user:'user', 
#          password: 'password',
#          host: 'host'
#          port: 5432, 
#          max_connections: 10)
#
# If a block is given to these methods, it is passed the opened Database
# object, which is closed (disconnected) when the block exits, just
# like a block passed to Sequel.connect.  For example:
#
#   Sequel.sqlite('blog.db'){|db| puts db[:users].count} 
#
# For a more expanded introduction, see the {README}[rdoc-ref:README.rdoc].
# For a quicker introduction, see the {cheat sheet}[rdoc-ref:doc/cheat_sheet.rdoc].
module Sequel
  @convert_two_digit_years = true
  @datetime_class = Time
  @split_symbols = false
  @single_threaded = false

  # Mutex used to protect mutable data structures
  @data_mutex = Mutex.new

  # Frozen hash used as the default options hash for most options.
  OPTS = {}.freeze

  SPLIT_SYMBOL_CACHE = {}

  module SequelMethods
    # Sequel converts two digit years in <tt>Date</tt>s and <tt>DateTime</tt>s by default,
    # so 01/02/03 is interpreted at January 2nd, 2003, and 12/13/99 is interpreted
    # as December 13, 1999. You can override this to treat those dates as
    # January 2nd, 0003 and December 13, 0099, respectively, by:
    #
    #   Sequel.convert_two_digit_years = false
    attr_accessor :convert_two_digit_years

    # Sequel can use either +Time+ or +DateTime+ for times returned from the
    # database.  It defaults to +Time+.  To change it to +DateTime+:
    #
    #   Sequel.datetime_class = DateTime
    #
    # Note that +Time+ and +DateTime+ objects have a different API, and in
    # cases where they implement the same methods, they often implement them
    # differently (e.g. + using seconds on +Time+ and days on +DateTime+).
    attr_accessor :datetime_class

    # Set whether Sequel is being used in single threaded mode. By default,
    # Sequel uses a thread-safe connection pool, which isn't as fast as the
    # single threaded connection pool, and also has some additional thread
    # safety checks.  If your program will only have one thread,
    # and speed is a priority, you should set this to true:
    #
    #   Sequel.single_threaded = true
    attr_accessor :single_threaded

    # Alias of original require method, as Sequel.require does a relative
    # require for backwards compatibility.
    alias orig_require require
    private :orig_require

    # Returns true if the passed object could be a specifier of conditions, false otherwise.
    # Currently, Sequel considers hashes and arrays of two element arrays as
    # condition specifiers.
    #
    #   Sequel.condition_specifier?({}) # => true
    #   Sequel.condition_specifier?([[1, 2]]) # => true
    #   Sequel.condition_specifier?([]) # => false
    #   Sequel.condition_specifier?([1]) # => false
    #   Sequel.condition_specifier?(1) # => false
    def condition_specifier?(obj)
      case obj
      when Hash
        true
      when Array
        !obj.empty? && !obj.is_a?(SQL::ValueList) && obj.all?{|i| i.is_a?(Array) && (i.length == 2)}
      else
        false
      end
    end

    # Creates a new database object based on the supplied connection string
    # and optional arguments.  The specified scheme determines the database
    # class used, and the rest of the string specifies the connection options.
    # For example:
    #
    #   DB = Sequel.connect('sqlite:/') # Memory database
    #   DB = Sequel.connect('sqlite://blog.db') # ./blog.db
    #   DB = Sequel.connect('sqlite:///blog.db') # /blog.db
    #   DB = Sequel.connect('postgres://user:password@host:port/database_name')
    #   DB = Sequel.connect('sqlite:///blog.db', max_connections: 10)
    #
    # You can also pass a single options hash:
    #
    #   DB = Sequel.connect(adapter: 'sqlite', database: './blog.db')
    #
    # If a block is given, it is passed the opened +Database+ object, which is
    # closed when the block exits.  For example:
    #
    #   Sequel.connect('sqlite://blog.db'){|db| puts db[:users].count}  
    #
    # If a block is not given, a reference to this database will be held in
    # <tt>Sequel::DATABASES</tt> until it is removed manually.  This is by
    # design, and used by <tt>Sequel::Model</tt> to pick the default
    # database.  It is recommended to pass a block if you do not want the
    # resulting Database object to remain in memory until the process
    # terminates, or use the <tt>keep_reference: false</tt> Database option.
    #
    # For details, see the {"Connecting to a Database" guide}[rdoc-ref:doc/opening_databases.rdoc].
    # To set up a primary/replica or sharded database connection, see the {"Primary/Replica Database Configurations and Sharding" guide}[rdoc-ref:doc/sharding.rdoc].
    def connect(*args, &block)
      Database.connect(*args, &block)
    end

    # Assume the core extensions are not loaded by default, if the core_extensions
    # extension is loaded, this will be overridden.
    def core_extensions?
      false
    end

    # Convert the +exception+ to the given class.  The given class should be
    # <tt>Sequel::Error</tt> or a subclass.  Returns an instance of +klass+ with
    # the message and backtrace of +exception+.
    def convert_exception_class(exception, klass)
      return exception if exception.is_a?(klass)
      e = klass.new("#{exception.class}: #{exception.message}")
      e.wrapped_exception = exception
      e.set_backtrace(exception.backtrace)
      e
    end

    # The current concurrency primitive, Thread.current by default.
    def current
      Thread.current
    end

    # Load all Sequel extensions given.  Extensions are just files that exist under
    # <tt>sequel/extensions</tt> in the load path, and are just required.  
    # In some cases, requiring an extension modifies classes directly, and in others,
    # it just loads a module that you can extend other classes with.  Consult the documentation
    # for each extension you plan on using for usage.
    #
    #   Sequel.extension(:blank)
    #   Sequel.extension(:core_extensions, :named_timezones)
    def extension(*extensions)
      extensions.each{|e| orig_require("sequel/extensions/#{e}")}
    end
    
    # The exception classed raised if there is an error parsing JSON.
    # This can be overridden to use an alternative json implementation.
    def json_parser_error_class
      JSON::ParserError
    end

    # Convert given object to json and return the result.
    # This can be overridden to use an alternative json implementation.
    def object_to_json(obj, *args, &block)
      obj.to_json(*args, &block)
    end

    # Parse the string as JSON and return the result.
    # This can be overridden to use an alternative json implementation.
    def parse_json(json)
      JSON.parse(json, :create_additions=>false)
    end

    # If a mutex is given, synchronize access using it.  If nil is given, just
    # yield to the block.  This is designed for cases where a mutex may or may
    # not be provided.
    def synchronize_with(mutex)
      if mutex
        mutex.synchronize{yield}
      else
        yield
      end
    end

    # Convert each item in the array to the correct type, handling multi-dimensional
    # arrays.  For each element in the array or subarrays, call the converter,
    # unless the value is nil.
    def recursive_map(array, converter)
      array.map do |i|
        if i.is_a?(Array)
          recursive_map(i, converter)
        elsif !i.nil?
          converter.call(i)
        end
      end
    end

    # For backwards compatibility only.  require_relative should be used instead.
    def require(files, subdir=nil)
      # Use Kernel.require_relative to work around JRuby 9.0 bug
      Array(files).each{|f| Kernel.require_relative "#{"#{subdir}/" if subdir}#{f}"}
    end

    # Splits the symbol into three parts, if symbol splitting is enabled (not the default).
    # Each part will either be a string or nil. If symbol splitting
    # is disabled, returns an array with the first and third parts
    # being nil, and the second part beind a string version of the symbol.
    #
    # For columns, these parts are the table, column, and alias.
    # For tables, these parts are the schema, table, and alias.
    def split_symbol(sym)
      unless v = Sequel.synchronize{SPLIT_SYMBOL_CACHE[sym]}
        if split_symbols?
          v = case s = sym.to_s
          when /\A((?:(?!__).)+)__((?:(?!___).)+)___(.+)\z/
            [$1.freeze, $2.freeze, $3.freeze].freeze
          when /\A((?:(?!___).)+)___(.+)\z/
            [nil, $1.freeze, $2.freeze].freeze
          when /\A((?:(?!__).)+)__(.+)\z/
            [$1.freeze, $2.freeze, nil].freeze
          else
            [nil, s.freeze, nil].freeze
          end
        else
          v = [nil,sym.to_s.freeze,nil].freeze
        end
        Sequel.synchronize{SPLIT_SYMBOL_CACHE[sym] = v}
      end
      v
    end

    # Setting this to true enables Sequel's historical behavior of splitting
    # symbols on double or triple underscores:
    #
    #   :table__column         # table.column
    #   :column___alias        # column AS alias
    #   :table__column___alias # table.column AS alias
    #
    # It is only recommended to turn this on for backwards compatibility until
    # such symbols have been converted to use newer Sequel APIs such as:
    #
    #   Sequel[:table][:column]            # table.column
    #   Sequel[:column].as(:alias)         # column AS alias
    #   Sequel[:table][:column].as(:alias) # table.column AS alias
    #
    # Sequel::Database instances do their own caching of literalized
    # symbols, and changing this setting does not affect those caches.  It is
    # recommended that if you want to change this setting, you do so directly
    # after requiring Sequel, before creating any Sequel::Database instances.
    #
    # Disabling symbol splitting will also disable the handling
    # of double underscores in virtual row methods, causing such methods to
    # yield regular identifers instead of qualified identifiers:
    #
    #   # Sequel.split_symbols = true
    #   Sequel.expr{table__column}  # table.column
    #   Sequel.expr{table[:column]} # table.column
    #
    #   # Sequel.split_symbols = false
    #   Sequel.expr{table__column}  # table__column
    #   Sequel.expr{table[:column]} # table.column
    def split_symbols=(v)
      Sequel.synchronize{SPLIT_SYMBOL_CACHE.clear}
      @split_symbols = v
    end

    # Whether Sequel currently splits symbols into qualified/aliased identifiers.
    def split_symbols?
      @split_symbols
    end

    # Converts the given +string+ into a +Date+ object.
    #
    #   Sequel.string_to_date('2010-09-10') # Date.civil(2010, 09, 10)
    def string_to_date(string)
      begin
        Date.parse(string, Sequel.convert_two_digit_years)
      rescue => e
        raise convert_exception_class(e, InvalidValue)
      end
    end

    # Converts the given +string+ into a +Time+ or +DateTime+ object, depending on the
    # value of <tt>Sequel.datetime_class</tt>.
    #
    #   Sequel.string_to_datetime('2010-09-10 10:20:30') # Time.local(2010, 09, 10, 10, 20, 30)
    def string_to_datetime(string)
      begin
        if datetime_class == DateTime
          DateTime.parse(string, convert_two_digit_years)
        else
          datetime_class.parse(string)
        end
      rescue => e
        raise convert_exception_class(e, InvalidValue)
      end
    end

    # Converts the given +string+ into a <tt>Sequel::SQLTime</tt> object.
    #
    #   v = Sequel.string_to_time('10:20:30') # Sequel::SQLTime.parse('10:20:30')
    #   DB.literal(v) # => '10:20:30'
    def string_to_time(string)
      begin
        SQLTime.parse(string)
      rescue => e
        raise convert_exception_class(e, InvalidValue)
      end
    end

    # Unless in single threaded mode, protects access to any mutable
    # global data structure in Sequel.
    # Uses a non-reentrant mutex, so calling code should be careful.
    # In general, this should only be used around the minimal possible code
    # such as Hash#[], Hash#[]=, Hash#delete, Array#<<, and Array#delete.
    def synchronize(&block)
      @single_threaded ? yield : @data_mutex.synchronize(&block)
    end

    if RUBY_VERSION >= '2.1'
      # A timer object that can be passed to Sequel.elapsed_seconds_since
      # to return the number of seconds elapsed.
      def start_timer
        Process.clock_gettime(Process::CLOCK_MONOTONIC)
      end
    else
      # :nocov:
      def start_timer # :nodoc:
        Time.now
      end
      # :nocov:
    end

    # The elapsed seconds since the given timer object was created.  The
    # timer object should have been created via Sequel.start_timer.
    def elapsed_seconds_since(timer)
      start_timer - timer
    end

    # Uses a transaction on all given databases with the given options. This:
    #
    #   Sequel.transaction([DB1, DB2, DB3]){}
    #
    # is equivalent to:
    #
    #   DB1.transaction do
    #     DB2.transaction do
    #       DB3.transaction do
    #       end
    #     end
    #   end
    #
    # except that if Sequel::Rollback is raised by the block, the transaction is
    # rolled back on all databases instead of just the last one.
    #
    # Note that this method cannot guarantee that all databases will commit or
    # rollback.  For example, if DB3 commits but attempting to commit on DB2
    # fails (maybe because foreign key checks are deferred), there is no way
    # to uncommit the changes on DB3.  For that kind of support, you need to
    # have two-phase commit/prepared transactions (which Sequel supports on
    # some databases).
    def transaction(dbs, opts=OPTS, &block)
      unless opts[:rollback]
        rescue_rollback = true
        opts = Hash[opts].merge!(:rollback=>:reraise)
      end
      pr = dbs.reverse.inject(block){|bl, db| proc{db.transaction(opts, &bl)}}
      if rescue_rollback
        begin
          pr.call
        rescue Sequel::Rollback
          nil
        end
      else
        pr.call
      end
    end

    # If the supplied block takes a single argument,
    # yield an <tt>SQL::VirtualRow</tt> instance to the block
    # argument.  Otherwise, evaluate the block in the context of a
    # <tt>SQL::VirtualRow</tt> instance.
    #
    #   Sequel.virtual_row{a} # Sequel::SQL::Identifier.new(:a)
    #   Sequel.virtual_row{|o| o.a} # Sequel::SQL::Function.new(:a)
    def virtual_row(&block)
      vr = VIRTUAL_ROW
      case block.arity
      when -1, 0
        vr.instance_exec(&block)
      else
        block.call(vr)
      end  
    end

    private

    # Helper method that the database adapter class methods that are added to Sequel via
    # metaprogramming use to parse arguments.
    def adapter_method(adapter, *args, &block)
      options = args.last.is_a?(Hash) ? args.pop : OPTS
      opts = {:adapter => adapter.to_sym}
      opts[:database] = args.shift if args.first.is_a?(String)
      if args.any?
        raise ::Sequel::Error, "Wrong format of arguments, either use (), (String), (Hash), or (String, Hash)"
      end

      connect(opts.merge(options), &block)
    end

    # Method that adds a database adapter class method to Sequel that calls
    # Sequel.adapter_method.
    def def_adapter_method(*adapters) # :nodoc:
      adapters.each do |adapter|
        define_singleton_method(adapter){|*args, &block| adapter_method(adapter, *args, &block)}
      end
    end
  end
  extend SequelMethods

    require_relative "deprecated"
    require_relative "sql"
    require_relative "connection_pool"
    require_relative "exceptions"
    require_relative "dataset"
    require_relative "database"
    require_relative "timezones"
    require_relative "ast_transformer"
    require_relative "version"

  class << self
    # Allow nicer syntax for creating Sequel expressions:
    #
    #   Sequel[1]     # => Sequel::SQL::NumericExpression: 1
    #   Sequel["a"]   # => Sequel::SQL::StringExpression: 'a'
    #   Sequel[:a]    # => Sequel::SQL::Identifier: "a"
    #   Sequel[a: 1]  # => Sequel::SQL::BooleanExpression: ("a" = 1)
    alias_method :[], :expr
  end

  # Add the database adapter class methods to Sequel via metaprogramming
  def_adapter_method(*Database::ADAPTERS)
end
