require "active_record"
# And require your chosen database adapter:
require "postgres_adapter"

class Person < ActiveRecord::Model

  # Set adapter to your chosen adapter name
  adapter postgres

  # Set table name, defaults to "#{lowercase_name}s"
  # table_name people

  # Database fields
  primary id                 : Int
  field last_name            : String
  field first_name           : String
  field number_of_dependents : Int

  # Domain logic
  def get_tax_exemption
    # ...
  end

  def get_taxable_earnings
    # ...
  end

end

# Combine .new(..) and #create
Person.new({ "first_name"           => "John",
             "last_name"            => "Smith",
             "number_of_dependents" => 3 }).create #=> #<Person: ...>

# Or shortcut with .create(..)
Person.create({ "first_name"           => "John",
                "last_name"            => "Smith",
                "number_of_dependents" => 3 })     #=> #<Person: ...>

Person.get(127)  #=> #<Person: @id=127, ...>

# Get all records
Person.all         # => [#<Person: ...>, #<Person: ...>, ...]

# Query by hash
Person.where({ "number_of_dependents" => 0 })   #=> [#<Person: ...>, #<Person: ...>, ...]

# Or construct a query object
include ActiveRecord::CriteriaHelper
Person.where(criteria("number_of_dependents") > 3)    #=> [#<Person: ...>, #<Person: ...>, ...]

person = Person.get(127)
person.number_of_dependents = 0
person.update

Person.get(127).delete

class Person < ActiveRecord::Model

  # Default is public for ease of use
  field_level :private
  # field_level :protected

  query_level :private
  # default is public, there is no point in protected here

  # ...
end

# Enforces you to maintain encapsulation, ie: not expose your data -
# put behavior in the same place the data it needs
person = Person.get(127)    # or Person[127]
person.first_name   #=> Error: unable to call private method first_name

# Enforces you to maintain DRYness to some extent, ie: not leak
# knowledge about your database structure, but put it in active record
# model and expose your own nit-picked methods
Person.where({ :first_name => "John" })    #=> Error: unable to call private method where

criteria("person_id") == 3                            # [person_id = :1, { "1" => 3 }]
criteria("person_id") == criteria("other_person_id")  # [person_id = other_person_id, {}]

criteria("number") <= 3                               # [number < :1, { "1" => 3 }]

(!(criteria("number") <= 3))                          # [(NOT (number <= :1)) AND (number <> :2),
  .and(criteria("number") != 5)                       #  { "1" => 3, "2" => 5 }]

criteria("subject_id").is_not_null                    # [(subject_id) IS NOT NULL, {}]

criteria("subject_id").in([37, 42, 45])

class Person < ActiveRecord::Model
  @@connection_pool_capacity = 25
  @@connection_pool_timeout = 0.03  # seconds
end

class User < ActiveRecord::Model
  has_many Post, criteria("posts.author_id") == criteria("users.id")
  # ...
end

class Post < ActiveRecord::Model
  belongs_to User, criteria("posts.author_id") == criteria("users.id")
  # ...
end

# makes only one join query
posts = Post.join(User).all
posts.first.title      # => "Hello world post"
posts.first.user.name  # => "John Smith"

# makes 2 queries - 'select from users' and 'select from posts'
user = User.all.first
user.posts.first.title  # => "Hello world post"
user.posts[1].title     # => "Yet another post"

# integration/integration_spec.cr
require "./spec_helper"

# integration/spec_helper.cr
require "spec"
require "../src/postgres_adapter"
require "active_record/null_adapter"

# Register our adapter as 'null' adapter, effectively overriding what was
# registered before by 'active_record':
ActiveRecord::Registry.register_adapter("null", PostgresAdapter::Adapter)

# Cleanup database before and after each example:
Spec.before_each do
  PostgresAdapter::Adapter._reset_do_this_only_in_specs_78367c96affaacd7
end
Spec.after_each do
  PostgresAdapter::Adapter._reset_do_this_only_in_specs_78367c96affaacd7
end

# Require fake adapter and kick off the integration spec
require "../modules/active_record/spec/fake_adapter"
require "../modules/active_record/spec/active_record_spec"

# src/postgres_adapter.cr
require "active_record"
require "active_record/adapter"

module PostgresAdapter
  class Adapter < ActiveRecord::Adapter
    def self.build(table_name, primary_field, fields, register = true)
      new(table_name, primary_field, fields, register)
    end

    def self.register(adapter)
      adapters << adapter
    end

    def self.adapters
      (@@_adapters ||= [] of self).not_nil!
    end

    getter table_name, primary_field, fields

    def initialize(@table_name, @primary_field, @fields, register = true)
      self.class.register(self)
    end

    def create(fields)
      0
    end

    def get(id)
      nil
    end

    def all
      [] of Hash(String, ActiveRecord::SupportedType)
    end

    def where(query_hash : Hash)
      all
    end

    def where(query : Query::Query)
      all
    end

    def update(id, fields)
    end

    def delete(id)
    end

    # Resets all data for all registered adapter instances of this kind
    def self._reset_do_this_only_in_specs_78367c96affaacd7
      adapters.each &_reset_do_this_only_in_specs_78367c96affaacd7
    end

    # Resets all data for current table (adapter instance)
    def _reset_do_this_only_in_specs_78367c96affaacd7
    end
  end
end

# At the end of src/postgres_adapter.cr
ActiveRecord::Registry.register_adapter("postgres", PostgresAdapter::Adapter)