require "config/environment"

MODEL_DIR   = File.join(RAILS_ROOT, "app/models")
FIXTURE_DIR = File.join(RAILS_ROOT, "test/fixtures")

module AnnotateModels

  PREFIX = "== Schema Information"
  
  # Simple quoting for the default column value
  def self.quote(value)
    case value
      when NilClass                 then "NULL"
      when TrueClass                then "TRUE"
      when FalseClass               then "FALSE"
      when Float, Fixnum, Bignum    then value.to_s
      # BigDecimals need to be output in a non-normalized form and quoted.
      when BigDecimal               then value.to_s('F')
      else
        value.inspect
    end
  end

  # Use the column information in an ActiveRecord class
  # to create a comment block containing a line for
  # each column. The line contains the column name,
  # the type (and length), and any optional attributes
  def self.get_schema_info(klass, header)
    info = "# == Model #{klass}\n# #{header}\n#\n"
    info << "# Table name: #{klass.table_name}\n#\n"
    
    max_size = klass.column_names.collect{|name| name.size}.max + 1
    klass.columns.each do |col|
      attrs = []
      attrs << "default(#{quote(col.default)})" if col.default
      attrs << "not null" unless col.null
      attrs << "primary key" if col.name == klass.primary_key

      col_type = col.type.to_s
      if col_type == "decimal"
        col_type << "(#{col.precision}, #{col.scale})"
      else
        col_type << "(#{col.limit})" if col.limit
      end 
      info << sprintf("#  %-#{max_size}.#{max_size}s:%-15.15s %s\n", col.name, col_type, attrs.join(", "))
    end
    assoc_list = klass.reflect_on_all_associations.sort {|x,y| d = x.class_name.to_s <=> y.class_name.to_s; c = d == 0 ? x.macro.to_s <=> y.macro.to_s : d; c == 0 ? x.name.to_s <=> y.name.to_s : c }
    unless assoc_list.empty?
      info << "#\n# == Associations\n" 
      assoc_list.each do |assoc|
        ao = assoc.options.dup
        ao.delete(:class_name)
        line = "# * " +sprintf("<tt>%-25s :%-25s (%s) %s</tt>", assoc.macro, assoc.name, assoc.class_name, ao.empty? ? '' : ao.inspect)
        info << line << "\n"
      end 
    end
    info << "#\n\n"
  end

  # Add a schema block to a file. If the file already contains
  # a schema info block (a comment starting
  # with "Schema as of ..."), remove it first.

  def self.annotate_one_file(file_name, info_block)
    if File.exist?(file_name)
      content = File.read(file_name)

      # Remove old schema info
      content.sub!(/^# #{PREFIX}.*?\n(#.*\n)*\n/, '')

      # Write it back
      File.open(file_name, "w") { |f| f.puts info_block + content }
    end
  end
  
  # Given the name of an ActiveRecord class, create a schema
  # info block (basically a comment containing information
  # on the columns and their types) and put it at the front
  # of the model and fixture source files.

  def self.annotate(klass, header)
    info = get_schema_info(klass, header)
    
    model_file_name = File.join(MODEL_DIR, klass.name.underscore + ".rb")
    annotate_one_file(model_file_name, info)

    fixture_file_name = File.join(FIXTURE_DIR, klass.table_name + ".yml")
    annotate_one_file(fixture_file_name, info)
  end

  # Return a list of the model files to annotate. If we have 
  # command line arguments, they're assumed to be either
  # the underscore or CamelCase versions of model names.
  # Otherwise we take all the model files in the 
  # app/models directory.
  def self.get_model_names
    models = ARGV.dup
    models.shift
    
    if models.empty?
      Dir.chdir(MODEL_DIR) do 
        models = Dir["**/*.rb"]
      end
    end
    models
  end

  # We're passed a name of things that might be 
  # ActiveRecord models. If we can find the class, and
  # if its a subclass of ActiveRecord::Base,
  # then pas it to the associated block

  def self.do_annotations
    header = PREFIX.dup
    version = ActiveRecord::Migrator.current_version rescue 0
    if version > 0
      header << "\n# Schema version: #{version}"
    end
    
    self.get_model_names.each do |m|
      class_name = m.sub(/\.rb$/,'').camelize
      begin
        klass = class_name.split('::').inject(Object){ |klass,part| klass.const_get(part) }
        if klass < ActiveRecord::Base && !klass.abstract_class?
          puts "Annotating #{class_name}"
          self.annotate(klass, header)
        else
          puts "Skipping #{class_name}"
        end
      rescue Exception => e
        puts "Unable to annotate #{class_name}: #{e.message}"
      end
      
    end
  end
end

# Just for fun and horror: make database functions a part of your Rails model! :)
#
# Class to access to PostgreSQL functions. Returned value depends on params and query result, see below.
#
# Currently supported options are:
#     :order => '1 desc' # to add order clause
#     :use_from => true  # to add "* from" for non-model function queries, which return records
#     :all => true       # to return not first but all found models
#     :cast => string    # to cast result (useful for functions, returning +setof record+)
#
# Call-patterns:
#
# A) Model loading from functions that return setof system known rowtype
#     PgProc.function(ModelClass[, options])
#         PgProc.get_descendants(ContentNode, 123)
#
#     PgProc.function(ModelClass, value[, options ])
#         PgProc.get_children(ContentNode, 123, :order => 'position', :all => true)
#
# returns either:
# * empty array if nothing found
# * first found model object, if found only one and +:all+ option is not set
# * array of model objects
#
# B) Values from functions
#
# PgProc.function(:type_symbol, value, [type_symbol2, value2, ...[, options]]) - for explicit parameter typecast
#     PgProc.array_append(:"int[]", '{1,2,3,4}', :int, 5) # => {1,2,3,4,5}
#
# PgProc.function(*args [, options])
#     PgProc.generate_series(1,10,2, :order => '1 desc') # => [9,5,7,3,2,1]
#
# PgProc.function() - for functions w/o params
#     PgProc.now()
#
# returns either:
# * empty string for +void+ functions
# * single value, if resultset has 1x1 dimension
# * array of values if resultset has Nx1 dimension (N>1)
# * array of rows otherwise
#
# Throws PGError, if function doesn't exist or wrong params supplied

class PgProc < ActiveRecord::Base
    set_table_name 'pg_catalog.pg_proc'
    set_primary_key 'oid'
    def readonly?
      true
    end

private
    def self.method_missing(meth_sym, *args)
      func_name = meth_sym.id2name
      super unless find(:first, :conditions => ['proname = ?', func_name])
      if ! args.empty? && args.last.is_a?(Hash)
        options = args.pop
        order_str = " ORDER BY #{options[:order]}" if options[:order]
      else
        options = {}
        order_str = nil
      end
      from_str = " * FROM " if options[:use_from]
      if args.empty?
        temp = connection.query("select #{from_str} #{func_name}() #{options[:cast]} #{order_str}")
      elsif args.first.is_a?(Class)
        model_klass = args.shift
        if args.length == 0
          temp = model_klass.find_by_sql("select * from  #{func_name}()  #{options[:cast]} #{order_str}")
        else
          temp = model_klass.find_by_sql("select * from  #{func_name}(#{quote_bound_value(args)})  #{options[:cast]} #{order_str}")
        end
        return temp if options[:all]
        return temp.length == 1 ? temp.first : temp
      else
          if args.length % 2 == 0 && args.first.is_a?(Symbol)
            temp = connection.query("select #{from_str} #{func_name}(#{quote_bound_value_types(args)}) #{options[:cast]} #{order_str}")
          else
            temp = connection.query("select #{from_str} #{func_name}(#{quote_bound_value(args)})  #{options[:cast]} #{order_str}")
          end
      end
      return temp.first.first if temp.length == 1 && temp.first.length == 1
      return temp.flatten if temp.length > 1 && temp.first.length == 1
      return temp
    end
    def self.quote_bound_value_types(value)
      i = true
      value.partition {|v| i = !i }.transpose.map{|v| "#{connection.quote(v[0])}::#{v[1]}"}.join(',')
    end
end