REFACTOR: Code generator for migrations IntemerdiateDB

* Splits the existing script into multiple classes
* Adds command for generating IntermediateDB schema (`migrations/bin/cli schema generate`)
* Changes the syntax of the IntermediateDB schema config
* Adds validation for the schema config
* It uses YAML schema aka JSON schema to validate the config file
* It generates the SQL schema file and Ruby classes for storing data in the IntermediateDB

migrations/lib/database/schema/model_writer.rb

@@ -0,0 +1,139 @@
+# frozen_string_literal: true
+
+require "rake"
+require "syntax_tree/rake_tasks"
+
+module Migrations::Database::Schema
+  class ModelWriter
+    def initialize(namespace, header)
+      @namespace = namespace
+      @header = header.gsub(/^/, "# ")
+    end
+
+    def self.filename_for(table)
+      "#{table.name.singularize}.rb"
+    end
+
+    def self.format_files(path)
+      glob_pattern = File.join(path, "**/*.rb")
+
+      system(
+        "bundle",
+        "exec",
+        "stree",
+        "write",
+        glob_pattern,
+        exception: true,
+        out: File::NULL,
+        err: File::NULL,
+      )
+    rescue StandardError
+      raise "Failed to run `bundle exec stree write '#{glob_pattern}'`"
+    end
+
+    def output_table(table, output_stream)
+      columns = table.sorted_columns
+
+      output_stream.puts "# frozen_string_literal: true"
+      output_stream.puts
+      output_stream.puts @header
+      output_stream.puts
+      output_stream.puts "module #{@namespace}"
+      output_stream.puts "  module #{to_singular_classname(table.name)}"
+      output_stream.puts "    SQL = <<~SQL"
+      output_stream.puts "      INSERT INTO #{escape_identifier(table.name)} ("
+      output_stream.puts column_names(columns)
+      output_stream.puts "      )"
+      output_stream.puts "      VALUES ("
+      output_stream.puts value_placeholders(columns)
+      output_stream.puts "      )"
+      output_stream.puts "    SQL"
+      output_stream.puts
+      output_stream.puts "    def self.create("
+      output_stream.puts method_parameters(columns)
+      output_stream.puts "    )"
+      output_stream.puts "      ::Migrations::Database::IntermediateDB.insert("
+      output_stream.puts "        SQL,"
+      output_stream.puts insertion_arguments(columns)
+      output_stream.puts "      )"
+      output_stream.puts "    end"
+      output_stream.puts "  end"
+      output_stream.puts "end"
+    end
+
+    private
+
+    def to_singular_classname(snake_case_string)
+      snake_case_string.singularize.camelize
+    end
+
+    def column_names(columns)
+      columns.map { |c| "        #{escape_identifier(c.name)}" }.join(",\n")
+    end
+
+    def value_placeholders(columns)
+      indentation = "        "
+      max_length = 100 - indentation.length
+      placeholder = "?, "
+      placeholder_count = columns.size
+
+      current_length = 0
+      placeholders = indentation.dup
+
+      (1..placeholder_count).each do |index|
+        placeholder = "?" if index == placeholder_count
+
+        if current_length + placeholder.length > max_length
+          placeholders.rstrip!
+          placeholders << "\n" << indentation
+          current_length = 0
+        end
+
+        placeholders << placeholder
+        current_length += placeholder.length
+      end
+
+      placeholders
+    end
+
+    def method_parameters(columns)
+      columns
+        .map do |c|
+          default_value = !c.is_primary_key && c.nullable ? " nil" : ""
+          "      #{c.name}:#{default_value}"
+        end
+        .join(",\n")
+    end
+
+    def insertion_arguments(columns)
+      columns
+        .map do |c|
+          argument =
+            case c.datatype
+            when :datetime
+              "::Migrations::Database.format_datetime(#{c.name})"
+            when :date
+              "::Migrations::Database.format_date(#{c.name})"
+            when :boolean
+              "::Migrations::Database.format_boolean(#{c.name})"
+            when :inet
+              "::Migrations::Database.format_ip_address(#{c.name})"
+            when :blob
+              "::Migrations::Database.to_blob(#{c.name})"
+            when :json
+              "::Migrations::Database.to_json(#{c.name})"
+            when :float, :integer, :numeric, :text
+              c.name
+            else
+              raise "Unknown dataype: #{type}"
+            end
+          "        #{argument},"
+        end
+        .join("\n")
+    end
+
+    def escape_identifier(identifier)
+      ::Migrations::Database::Schema.escape_identifier(identifier)
+    end
+  end
+end