-- ═══════════════════════════════════════════════════════════════
-- 007  TIMELINE
--
-- The history page's spine. One row per thing worth putting on the
-- rail, and — this is the whole point — a row that points at an
-- event holds almost nothing of its own. Title, date and logo are
-- read back from `events` at query time, so editing the event edits
-- the timeline and there is no second copy to drift.
--
-- Decade headers are NOT here. There are four of them, they change
-- about never, and they are editorial voice rather than record; they
-- live in src/data/historyDecades.ts.
--
-- ref_kind + ref_id is polymorphic, matching content_blocks and
-- links rather than inventing a second pattern. SQLite can't express
-- that as a foreign key, so the triggers below do the work one
-- would, exactly as those two tables already do.
--
--   PRAGMA user_version;   -- was 6 before this file
-- ═══════════════════════════════════════════════════════════════

CREATE TABLE timeline_entries (
  id            INTEGER PRIMARY KEY AUTOINCREMENT,

  -- What the entry is about, which drives the marker and the body
  -- layout on the page. Usually mirrors ref_kind; 'people' is the
  -- exception, being a team ref rendered as a roster, and
  -- 'milestone' is the free-standing case with no ref at all.
  kind          TEXT NOT NULL DEFAULT 'milestone'
                  CHECK (kind IN ('milestone', 'event', 'organization',
                                  'award', 'people')),

  ref_kind      TEXT CHECK (ref_kind IN ('event', 'organization', 'award',
                                         'person', 'team')),
  ref_id        TEXT,

  -- Null inherits from the referenced row: an event's starts_on. A
  -- hand-authored entry has to supply its own, which the descriptor
  -- can't require conditionally — the read layer reports an entry
  -- with neither rather than the table refusing it.
  occurred_on   TEXT,

  -- How much of occurred_on is trustworthy. Backfilled rows often
  -- have a full date where only the year is actually known, and
  -- 'year' is what routes them to "Elsewhere in 2009" instead of
  -- asserting a month nobody can source.
  precision     TEXT NOT NULL DEFAULT 'day'
                  CHECK (precision IN ('year', 'month', 'day')),

  -- All null-inherits-from-the-ref. Filling one in is an override,
  -- for when the timeline wants to say something the event card
  -- doesn't.
  title         TEXT,
  blurb         TEXT,
  meta          TEXT,
  link_url      TEXT,

  is_featured   INTEGER NOT NULL DEFAULT 0 CHECK (is_featured IN (0, 1)),
  is_published  INTEGER NOT NULL DEFAULT 1 CHECK (is_published IN (0, 1)),
  sort_order    INTEGER NOT NULL DEFAULT 0,

  created_at    TEXT NOT NULL DEFAULT (datetime('now')),
  updated_at    TEXT NOT NULL DEFAULT (datetime('now')),

  -- Half a reference is worse than none: it would resolve to a link
  -- with no destination and no way to notice.
  CHECK ((ref_kind IS NULL) = (ref_id IS NULL)),

  -- One timeline entry per referenced record, which is what makes
  -- the in_timeline checkbox an upsert rather than a duplicate
  -- factory. SQLite permits any number of NULL pairs here, so
  -- hand-authored entries are unaffected.
  UNIQUE (ref_kind, ref_id)
) STRICT;

CREATE INDEX timeline_entries_date_idx
  ON timeline_entries (is_published, occurred_on DESC);


-- Who an entry is about, when it isn't a whole team. A 'people'
-- entry naming a team resolves its roster through v_org_leadership
-- instead and leaves this table empty; this is for the cases where
-- the list is editorial rather than structural.
--
-- Safe for the CRUD engine's delete-and-reinsert because nothing
-- references these rows.
CREATE TABLE timeline_entry_people (
  entry_id    INTEGER NOT NULL REFERENCES timeline_entries (id) ON DELETE CASCADE,
  person_id   TEXT NOT NULL REFERENCES people (id) ON DELETE CASCADE,
  note        TEXT,                      -- 'Founding lead'
  sort_order  INTEGER NOT NULL DEFAULT 0,
  PRIMARY KEY (entry_id, person_id)
) STRICT;

CREATE INDEX timeline_entry_people_person_idx
  ON timeline_entry_people (person_id);


-- ── The checkbox on the event and organization editors ─────────
--
-- Not a denormalised copy of "does a timeline row exist" — it is the
-- gate the admin descriptor reads. Ticked, the extension upserts a
-- timeline_entries row; unticked, the engine deletes it. The flag
-- and the row are written in the same transaction, so they cannot
-- disagree.
ALTER TABLE events
  ADD COLUMN in_timeline INTEGER NOT NULL DEFAULT 0
    CHECK (in_timeline IN (0, 1));

ALTER TABLE organizations
  ADD COLUMN in_timeline INTEGER NOT NULL DEFAULT 0
    CHECK (in_timeline IN (0, 1));


-- ── Integrity for the polymorphic reference ────────────────────

CREATE TRIGGER timeline_entries_ref_exists
BEFORE INSERT ON timeline_entries
BEGIN
  SELECT CASE
    WHEN new.ref_kind = 'event'
         AND NOT EXISTS (SELECT 1 FROM events WHERE id = new.ref_id)
      THEN RAISE(ABORT, 'timeline_entries: no such event')
    WHEN new.ref_kind = 'organization'
         AND NOT EXISTS (SELECT 1 FROM organizations WHERE id = new.ref_id)
      THEN RAISE(ABORT, 'timeline_entries: no such organization')
    WHEN new.ref_kind = 'award'
         AND NOT EXISTS (SELECT 1 FROM awards WHERE id = new.ref_id)
      THEN RAISE(ABORT, 'timeline_entries: no such award')
    WHEN new.ref_kind = 'person'
         AND NOT EXISTS (SELECT 1 FROM people WHERE id = new.ref_id)
      THEN RAISE(ABORT, 'timeline_entries: no such person')
    WHEN new.ref_kind = 'team'
         AND NOT EXISTS (SELECT 1 FROM teams WHERE id = new.ref_id)
      THEN RAISE(ABORT, 'timeline_entries: no such team')
  END;
END;

-- The same check on update, because the standalone editor can
-- repoint an entry at a different record.
CREATE TRIGGER timeline_entries_ref_exists_update
BEFORE UPDATE OF ref_kind, ref_id ON timeline_entries
BEGIN
  SELECT CASE
    WHEN new.ref_kind = 'event'
         AND NOT EXISTS (SELECT 1 FROM events WHERE id = new.ref_id)
      THEN RAISE(ABORT, 'timeline_entries: no such event')
    WHEN new.ref_kind = 'organization'
         AND NOT EXISTS (SELECT 1 FROM organizations WHERE id = new.ref_id)
      THEN RAISE(ABORT, 'timeline_entries: no such organization')
    WHEN new.ref_kind = 'award'
         AND NOT EXISTS (SELECT 1 FROM awards WHERE id = new.ref_id)
      THEN RAISE(ABORT, 'timeline_entries: no such award')
    WHEN new.ref_kind = 'person'
         AND NOT EXISTS (SELECT 1 FROM people WHERE id = new.ref_id)
      THEN RAISE(ABORT, 'timeline_entries: no such person')
    WHEN new.ref_kind = 'team'
         AND NOT EXISTS (SELECT 1 FROM teams WHERE id = new.ref_id)
      THEN RAISE(ABORT, 'timeline_entries: no such team')
  END;
END;


-- Deleting the record deletes its entry. Separate triggers rather
-- than editing the existing *_cleanup ones, so this migration adds
-- and never rewrites.
CREATE TRIGGER timeline_events_cleanup
AFTER DELETE ON events
BEGIN
  DELETE FROM timeline_entries WHERE ref_kind = 'event' AND ref_id = old.id;
END;

CREATE TRIGGER timeline_organizations_cleanup
AFTER DELETE ON organizations
BEGIN
  DELETE FROM timeline_entries WHERE ref_kind = 'organization' AND ref_id = old.id;
END;

CREATE TRIGGER timeline_awards_cleanup
AFTER DELETE ON awards
BEGIN
  DELETE FROM timeline_entries WHERE ref_kind = 'award' AND ref_id = old.id;
END;

CREATE TRIGGER timeline_people_cleanup
AFTER DELETE ON people
BEGIN
  DELETE FROM timeline_entries WHERE ref_kind = 'person' AND ref_id = old.id;
END;

CREATE TRIGGER timeline_teams_cleanup
AFTER DELETE ON teams
BEGIN
  DELETE FROM timeline_entries WHERE ref_kind = 'team' AND ref_id = old.id;
END;


-- updated_at, with the same WHEN guard as the other touch triggers
-- so an explicit value passes through untouched on import.
CREATE TRIGGER timeline_entries_touch
AFTER UPDATE ON timeline_entries
FOR EACH ROW WHEN new.updated_at = old.updated_at
BEGIN
  UPDATE timeline_entries SET updated_at = datetime('now') WHERE id = new.id;
END;


-- ── Read view ──────────────────────────────────────────────────
--
-- Every fallback the page depends on, resolved once here rather than
-- restated by each route. An entry with no title of its own takes
-- the referenced record's name; with no date, the event's starts_on.
--
-- org_kind rides along because /regions, /chapters and /partners are
-- three different routes and only this table knows which a slug is.
--
-- effective_date is the sort key. An entry that ended up with no
-- date at all sorts last rather than vanishing, so a missing one is
-- visible in the admin instead of silently absent from the page.
CREATE VIEW v_timeline AS
SELECT
  t.id,
  t.kind,
  t.ref_kind,
  t.ref_id,
  t.precision,
  t.is_featured,
  t.is_published,
  t.sort_order,

  COALESCE(t.occurred_on, e.starts_on, pa.awarded_on)   AS effective_date,

  COALESCE(
    t.title,
    e.title,
    o.name,
    aw.name,
    p.display_name,
    tm.name
  )                                                     AS effective_title,

  COALESCE(t.blurb, e.tagline, o.tagline, aw.description, p.tagline, tm.tagline)
                                                        AS effective_blurb,
  t.meta,
  t.link_url,

  -- Filename only. The directory is the frontend's business.
  COALESCE(e.event_logo, e.org_logo, o.logo, aw.logo, p.photo, tm.logo)
                                                        AS effective_logo,

  o.kind                                                AS org_kind,
  tm.org_id                                             AS team_org_id,
  tm.name                                               AS team_name,

  -- Whether the referenced record is itself visible. An entry must not
  -- outlive the thing it points at being unpublished — a draft event
  -- would otherwise leak its title and date onto a public page. Null
  -- for a standalone milestone, which answers to nothing but its own
  -- is_published.
  CASE t.ref_kind
    WHEN 'event'        THEN e.is_published
    WHEN 'organization' THEN o.is_published
    WHEN 'person'       THEN p.is_published
    WHEN 'team'         THEN tm.is_published
    ELSE NULL
  END                                                   AS ref_is_published,
  t.occurred_on,
  t.title                                               AS title_override
FROM timeline_entries t
LEFT JOIN events        e  ON t.ref_kind = 'event'        AND e.id  = t.ref_id
LEFT JOIN organizations o  ON t.ref_kind = 'organization' AND o.id  = t.ref_id
LEFT JOIN awards        aw ON t.ref_kind = 'award'        AND aw.id = t.ref_id
LEFT JOIN people        p  ON t.ref_kind = 'person'       AND p.id  = t.ref_id
LEFT JOIN teams         tm ON t.ref_kind = 'team'         AND tm.id = t.ref_id
LEFT JOIN person_awards pa ON t.ref_kind = 'award'        AND pa.award_id = t.ref_id
                              AND pa.id = (SELECT MIN(id) FROM person_awards
                                            WHERE award_id = t.ref_id);

PRAGMA user_version = 7;