Add Agent and Agency models

Since IN COMMON is about collective management of data
we're using the concept of Agent to describe a group of
users acting together.

In ActivityPub terms, Agent will be the Actor when manipulating
data, so that any individual User (or application) member of this
Agent will be able to manipulate data on behalf of this Agent.

Therefore a User has many Agencies, and an Agent as well: the
Agency model allows not only to create a joint table between Agents
and Users, but also to manage User roles within the related Agent.

Roles are defined as:
- observer: one who can read and review or flag data
- editor: one who create or edit data
- maintainer: one who can edit data and manage maps
- leader: one who can manage roles

A User may have zero or more roles in an Agent.
A User without a Agency record for a specific Agent will only be
able to 'observe' public data from this Agent.

(Note that this is not currently specified, but matches existing
reflection on Agents)

https://doc.incommon.cc/#agents

5 files changed, 83 insertions, 1 deletions

diff --git a/app/models/agency.rb b/app/models/agency.rb
new file mode 100644
index 0000000..fe81687
--- /dev/null
+++ b/app/models/agency.rb
@@ -0,0 +1,22 @@
+class Agency < ApplicationRecord
+  include Bitfields
+
+  belongs_to :agent
+  belongs_to :user
+
+  bitfield :roles, :observer, :editor, :maintainer, :leader
+
+  class << self
+    # Grant role in agent to user
+    def grant(agent, user, role)
+      r = find_or_create_by(agent: agent, user: user)
+      r&.public_send("#{role}=", true) && r&.save
+    end
+
+    # Revoke role in agent from user
+    def revoke(agent, user, role)
+      r = find_by(agent: agent, user: user)
+      r&.public_send("#{role}=", false) && r&.save
+    end
+  end
+end
diff --git a/app/models/agent.rb b/app/models/agent.rb
new file mode 100644
index 0000000..bb33c1b
--- /dev/null
+++ b/app/models/agent.rb
@@ -0,0 +1,4 @@
+class Agent < ApplicationRecord
+  has_many :agencies
+  has_many :members, through: :agencies, source: :user
+end
diff --git a/db/migrate/20201005154908_create_agents.rb b/db/migrate/20201005154908_create_agents.rb
new file mode 100644
index 0000000..32792ee
--- /dev/null
+++ b/db/migrate/20201005154908_create_agents.rb
@@ -0,0 +1,11 @@
+class CreateAgents < ActiveRecord::Migration[6.0]
+  def change
+    create_table :agents do |t|
+      t.string :name
+      t.uuid :uuid
+
+      t.timestamps
+    end
+    add_index :agents, [:uuid], unique: true
+  end
+end
diff --git a/db/migrate/20201005155004_create_agencies.rb b/db/migrate/20201005155004_create_agencies.rb
new file mode 100644
index 0000000..ab7cb03
--- /dev/null
+++ b/db/migrate/20201005155004_create_agencies.rb
@@ -0,0 +1,12 @@
+class CreateAgencies < ActiveRecord::Migration[6.0]
+  def change
+    create_table :agencies do |t|
+      t.references :agent, null: false, foreign_key: true
+      t.references :user, null: false, foreign_key: true
+      t.integer :roles, default: 0, null: false, limit: 2
+
+      t.timestamps
+    end
+    add_index :agencies, [:agent_id, :user_id], unique: true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index b10373b..ef4f4cd 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,9 +10,42 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 0) do
+ActiveRecord::Schema.define(version: 2020_10_05_155004) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
+  create_table "agencies", force: :cascade do |t|
+    t.bigint "agent_id", null: false
+    t.bigint "user_id", null: false
+    t.integer "roles", limit: 2, default: 0, null: false
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+    t.index ["agent_id", "user_id"], name: "index_agencies_on_agent_id_and_user_id", unique: true
+    t.index ["agent_id"], name: "index_agencies_on_agent_id"
+    t.index ["user_id"], name: "index_agencies_on_user_id"
+  end
+
+  create_table "agents", force: :cascade do |t|
+    t.string "name"
+    t.uuid "uuid"
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+    t.index ["uuid"], name: "index_agents_on_uuid", unique: true
+  end
+
+  create_table "users", force: :cascade do |t|
+    t.string "name"
+    t.string "username"
+    t.string "email"
+    t.bigint "external_id"
+    t.string "avatar_url"
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+    t.index ["email"], name: "index_users_on_email", unique: true
+    t.index ["external_id"], name: "index_users_on_external_id", unique: true
+  end
+
+  add_foreign_key "agencies", "agents"
+  add_foreign_key "agencies", "users"
 end