#!/usr/bin/env ruby

model = ARGV[0]
unless model
  $stderr.puts "usage: skewer ModelName"
  exit 1
end

require 'config/boot'
require 'config/environment'

model = Object.const_get(model)

unless defined?(Mongoid) and Mongoid::Document > model
  $stderr.puts "#{model} must be a Mongoid::Document"
  exit 1
end

write_schema = true
write_squeal = true

schema_filename = "#{model.name.underscore}_schema.sql"
squeal_filename = "#{model.name.underscore}_squeal.rb"

schema_exists = File.exists?(schema_filename)
squeal_exists = File.exists?(squeal_filename)

if schema_exists || squeal_exists
  $stdout.print "#{schema_filename} already exists, overwrite? [Y/n] "
  write_schema = $stdin.gets.chomp != "n"

  $stdout.print "#{squeal_filename} already exists, overwrite? [Y/n] "
  write_squeal = $stdin.gets.chomp != "n"
end

fields = model.fields.values.sort_by(&:name)
associations = model.associations

# SQL #
def create_table(model, parent = nil)
  fields = model.fields.values.sort_by(&:name)
  columns = []
  columns << "`#{parent.name.underscore}_id` CHAR(24)" if parent

  fields.each do |field|
    mysql_type = case field.type.name
                 when "Boolean"
                   "BOOLEAN"
                 when "Time"
                   "TIMESTAMP NULL DEFAULT NULL"
                 when "Date"
                   "DATE"
                 when "Float"
                   "FLOAT"
                 when "Integer"
                   "INT"
                 else
                   "TEXT"
                 end
    columns << "`#{field.name[0..63]}` #{mysql_type}"
  end

  table_name = if parent
                 "#{parent.name.underscore}_#{model.name.underscore}"
               else
                 "#{model.name.underscore}"
               end

  table_sql = []
  table_sql << "DROP TABLE IF EXISTS `#{table_name}`;"
  table_sql << "CREATE TABLE `#{table_name}` (`id` CHAR(24) PRIMARY KEY);"
  columns.each do |column|
    table_sql << "ALTER TABLE `#{table_name}` ADD COLUMN #{column};"
  end

  table_sql.join("\n") + "\n"
end

# SQUEAL #
def create_squeal(model, indent=false, parents = [])
  fields = model.fields.values.sort_by(&:name)

  parent = parents.last
  table_name = if parent
                 "#{parent.name.underscore}_#{model.name.underscore}"
               else
                 "#{model.name.underscore}"
               end

  squeal = if parent
    "#{parent.name.underscore}.#{model.name.tableize}.each do |#{model.name.underscore}|\n" \
    "  #{table_name} = #{model.name.underscore}"
  else
    "import.source(\"#{model.name.tableize}\").each do |#{model.name.underscore}|"
  end

  schemas = [create_table(model, parent)]

  squeal << <<-EOS

  target(:#{table_name}) do
  EOS
  if parent
    squeal << <<-EOS
    assign(:#{parent.name.underscore}_id)
    EOS
  end

  fields.each do |field|
    field_name = field.name
    case
    when %w(type target).include?(field.name)
      value = " { #{table_name}['#{field.name}'] }"
    when field.name.size > 64
      field_name = field.name[0..63]
      value = " { #{table_name}.#{field.name} }"
    when field.name =~ /(.*)_id$/
      value = " { #{table_name}.#{$1} }"
    end
    squeal << <<-EOS
    assign(:#{field_name})#{value}
    EOS
  end

  model.associations.values.each do |association|
    begin
      if [Mongoid::Associations::HasMany, Mongoid::Associations::HasOne].include?(association.association)
        unless parents.include?(association.klass)
          ruby, sql = create_squeal(association.klass, true, parents | [model]) 
          squeal << "\n" + ruby + "\n"
          schemas |= sql
        end
      end
    rescue NameError
    end
  end

  squeal << <<-EOS
  end
end # #{table_name}
  EOS
  squeal.gsub!(/^/, "    ") if indent
  return squeal, schemas
end

squeal, schema = create_squeal(model)

if write_squeal
  File.open(squeal_filename, "w") do |file|
    file.write <<-EOS
require 'squealer'

import('localhost', 27017, 'development') # <--- Change this as needed
export('localhost', 'root', '', 'export') # <--- Change this as needed

EOS
    file.write(squeal)
  end
end

if write_schema
  File.open(schema_filename, "w") do |file|
    file.write(schema.join("\n"))
  end
end