Unify Note and Index classes into Page.

Once integrated with the parser, this will be a breaking API change.

- Any `Page` may contain child pages and belong to any other page.
- Use `Page#is_index?` to check if it is an "index" page - i.e. a page
that has children.
- Page entities are considered equal if their slug is equal
- Added `Page.create_root` factory method

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## [Unreleased]
 
 - Rename `Obsidian::MarkdownConverter` to `Obsidian::ParsedMarkdownDocument`
+- Unify `Note` and `Index` classes into `Page`. This is a breaking API change.
 
 ## [0.3.0] - 2023-07-27
 

lib/obsidian/parser.rb

@@ -3,6 +3,7 @@
 require_relative "parser/version"
 require_relative "parser/parsed_markdown_document"
 require_relative "parser/obsidian_flavored_markdown"
+require_relative "parser/page"
 
 module Obsidian
   class Error < StandardError; end

lib/obsidian/parser/page.rb

@@ -0,0 +1,87 @@
+# frozen_string_literal: true
+
+module Obsidian
+  # A page in the vault corresponding to either a markdown document,
+  # or a directory containing other documents.
+  #
+  # If a directory contains an index.md, that is used as the content of
+  # the directory page; otherwise content will be nil.
+  class Page
+    def self.create_root
+      Page.new(title: "", slug: "")
+    end
+
+    def initialize(title:, slug:, last_modified: nil, content: nil, parent: nil)
+      # TODO: check frontmatter for titles as well
+      @title = title
+      @slug = slug
+      @last_modified = last_modified
+      @content = content
+      @parent = parent
+      @children = {}
+    end
+
+    def is_index?
+      !children.empty?
+    end
+
+    def inspect
+      "Page(title: #{title.inspect}, slug: #{slug.inspect})"
+    end
+
+    def ==(other)
+      !slug.nil? && slug == other.slug
+    end
+
+    alias_method :eql?, :==
+
+    def hash
+      slug.hash
+    end
+
+    # Add a note to the tree based on its slug.
+    # Call this method on the root page.
+    # When calling this method, you must ensure that anscestor pages
+    # are added before their descendents.
+    def add_page(slug, last_modified: nil, content: nil)
+      path_components = slug.split("/")
+      raise ArgumentError, "Expecting non-empty slug" if path_components.empty?
+
+      title = path_components.pop
+
+      parent = path_components.reduce(self) do |index, anscestor_title|
+        anscestor_slug = Obsidian.build_slug(anscestor_title, index.slug)
+        index.get_or_create_child(slug: anscestor_slug, title: anscestor_title)
+      end
+
+      parent.get_or_create_child(
+        title: title,
+        slug: slug,
+        last_modified: last_modified,
+        content: content
+      )
+    end
+
+    def get_or_create_child(title:, slug:, last_modified: nil, content: nil)
+      # TODO: validate slug matches the current page slug
+
+      @children[title] ||= Page.new(
+        slug: slug,
+        title: title,
+        last_modified: last_modified,
+        content: content,
+        parent: self
+      )
+    end
+
+    def children
+      @children.values.sort_by { |c| [c.is_index? ? 1 : 0, c.title] }
+    end
+
+    attr_reader :title
+    attr_reader :slug
+    attr_reader :last_modified
+    attr_reader :content
+    attr_reader :parent
+  end
+end

spec/obsidian/parser/page_spec.rb

@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+RSpec.describe Obsidian::Page do
+  subject(:root) { described_class.create_root }
+
+  describe("#add_page") do
+    it "relates too pages" do
+      page = root.add_page("foo")
+
+      expect(page.parent).to eq(root)
+      expect(root.children).to eq([page])
+    end
+
+    it "assigns titles and slugs to a top level page" do
+      page = root.add_page("foo")
+
+      expect(page.slug).to eq("foo")
+      expect(page.title).to eq("foo")
+    end
+
+    it "assigns titles and slugs to a nested page" do
+      page = root.add_page("foo/bar/baz")
+
+      expect(page.slug).to eq("foo/bar/baz")
+      expect(page.title).to eq("baz")
+    end
+
+    it "infers missing directory pages" do
+      page = root.add_page("foo/bar/baz")
+      parent = page.parent
+      grandparent = parent.parent
+
+      expect(parent.slug).to eq("foo/bar")
+      expect(grandparent.slug).to eq("foo")
+      expect(parent.children).to eq([page])
+      expect(grandparent.children).to eq([parent])
+      expect(root.children).to eq([grandparent])
+    end
+  end
+end