-- This is undoubtedly one of the more complex bits of code I've
-- written recently, and I do wish there had been macros because
-- there's a lot of hand-written, copy-pasted code here around the
-- basic content of a note; it would have been nice to be able to DRY
-- that out.

-- This expression creates a table, 'notetree', that contains all of
-- the notes nested under a page.  Each entry in the table includes
-- the note's parent's internal and external ids so that applications
-- can build an actual tree out of a vec of these things.

-- TODO: Extensive testing to validate that the nodes are delivered
-- *in nesting order* to the client.

SELECT
  id,
  uuid,
  parent_id,
  parent_uuid,
  content,
  position,
  notetype,
  creation_date,
  updated_date,
  lastview_date,
  deleted_date

FROM (

  WITH RECURSIVE notetree (
    id,
    uuid,
    parent_id,
    parent_uuid,
    content,
    position,
    notetype,
    creation_date,
    updated_date,
    lastview_date,
    deleted_date,
    cycle
  )

  AS (

    SELECT
      notes.id,
      notes.uuid,
      notes.id AS parent_id,
      notes.uuid AS parent_uuid,
      notes.content,
      0,  -- Root notes are always in position 0
      notes.notetype,
      notes.creation_date,
      notes.updated_date,
      notes.lastview_date,
      notes.deleted_date,
      ','||notes.id||','  -- Cycle monitor
     FROM notes
     WHERE notes.id = ? AND notes.notetype = "root"

-- RECURSIVE expression
    UNION SELECT
      notes.id,
      notes.uuid,
      notetree.id AS parent_id,
      notetree.uuid AS parent_uuid,
      notes.content,
      note_relationships.position,
      notes.notetype,
      notes.creation_date,
      notes.updated_date,
      notes.lastview_date,
      notes.deleted_date,
      notetree.cycle||notes.id||','
        FROM notes
          INNER JOIN note_relationships 
            ON notes.id = note_relationships.note_id
      -- For a given ID in the level of notetree in *this* recursion,
      -- we want each note's branches one level down.
          INNER JOIN notetree 
            ON note_relationships.parent_id = notetree.id
      -- And we want to make sure there are no cycles.  There shouldn't
      -- be; we're supposed to prevent those.  But you never know.
          WHERE notetree.cycle NOT LIKE '%,'||notes.id||',%'
          ORDER BY note_relationships.position
    )

  SELECT * from notetree);