feat: add MindMap, Node and Edges

api/app/controllers/mindmaps_controller.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class MindmapsController < ApplicationController
+  before_action :authenticate_request, only: :create
+
+  def show
+    @mm = MindMap.find(params[:id])
+  end
+
+  def index
+    @mmaps = MindMap.all
+  end
+
+  def create
+    # TBD
+  end
+end

api/app/models/edge.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class Edge < ApplicationRecord
+  belongs_to :from_node, class_name: 'Node'
+  belongs_to :to_node, class_name: 'Node'
+
+  validates :from_node_id, presence: true
+  validates :to_node_id, presence: true
+
+  scope :between, ->(from, to) { where(from_node_id: from.id, to_node_id: to.id) }
+end

api/app/models/mind_map.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class MindMap < ApplicationRecord
+  belongs_to :category
+  has_many :nodes, foreign_key: 'graph_id'
+
+  scope :for_category, ->(category) { where(category_id: category.id) }
+
+  def add_node(node)
+    node.update!(graph_id: self.id)
+  end
+
+  def remove_node(node)
+    node.update!(graph_id: nil)
+  end
+
+  def connect_nodes(from, to)
+    Edge.create(from_node: from, to_node: to)
+  end
+end

api/app/models/node.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class Node < ApplicationRecord
+  belongs_to :nodeable, polymorphic: true
+  belongs_to :graph, class_name: 'MindMap', foreign_key: 'graph_id', optional: true
+
+  has_many :edges, dependent: :destroy
+  has_many :edges, foreign_key: 'to_node_id'
+
+  validates :nodeable_type, presence: true
+  validates :nodeable_id, presence: true
+
+  scope :related_to_exam, ->(exam) { where(nodeable_type: 'Exam', nodeable_id: exam.id) }
+end

api/app/models/user.rb

@@ -10,5 +10,6 @@ class User < ApplicationRecord
 
   has_many :answer
   has_many :exams, through: :answer
+  has_many :mind_map
   has_one :garden
 end

api/app/views/mindmaps/index.jbuilder

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+json.array! @mmaps do |map|
+  json.id map.id
+  json.name map.name
+  json.owner_id map.user_id
+  json.node_count map.node_ids.count
+end

api/app/views/mindmaps/show.jbuilder

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+json.message 'Your mind map'
+json.name @mm.name
+json.category @mm.category.title
+json.nodes @mm.node_ids

api/config/routes.rb

@@ -32,5 +32,6 @@
       post '/journal/surprise_question', to: 'gardens#evaluate_surprise_question'
     end
     resources :trees, only: %i[index show]
+    resources :mindmaps
   end
 end

api/db/migrate/20240907184721_create_mind_maps.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class CreateMindMaps < ActiveRecord::Migration[7.0]
+  def change
+    create_table :mind_maps do |t|
+      t.string :name
+      t.references :category, null: false, foreign_key: true
+      t.references :user, null: false, foreign_key: true
+
+      t.timestamps
+    end
+  end
+end

api/db/migrate/20240907184819_create_nodes.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class CreateNodes < ActiveRecord::Migration[7.0]
+  def change
+    create_table :nodes do |t|
+      t.references :nodeable, polymorphic: true, null: false
+      t.integer :position
+
+      t.timestamps
+    end
+
+    add_index :nodes, %i[nodeable_type nodeable_id], name: 'index_nodes_on_nodeable_type_and_nodeable_id', unique: true
+  end
+end

api/db/migrate/20240907184914_create_edges.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class CreateEdges < ActiveRecord::Migration[7.0]
+  def change
+    create_table :edges do |t|
+      t.references :from_node, null: false, foreign_key: { to_table: :nodes }
+      t.references :to_node, null: false, foreign_key: { to_table: :nodes }
+
+      t.timestamps
+    end
+
+    add_index :edges, %i[from_node_id to_node_id], name: 'index_edges_on_from_node_id_and_to_node_id', unique: true
+  end
+end

api/db/migrate/20240915162642_add_graph_id_to_nodes.rb

@@ -0,0 +1,5 @@
+class AddGraphIdToNodes < ActiveRecord::Migration[7.0]
+  def change
+    add_column :nodes, :graph_id, :integer
+  end
+end