-- main.wo — the smallest complete writeonce program.
--
-- Run it from the repo root:
--
--   cargo run --bin wo -- run docs/examples/hello     (or: just hello)
--   just hello-demo                                   -- scripted CRUD round-trip
--
-- and exercise it:
--
--   curl -X POST localhost:8080/api/notes \
--        -H "Content-Type: application/json" \
--        -d '{"title":"hello","body":"# First note"}'
--   curl localhost:8080/api/notes
--   curl localhost:8080/api/notes/1
--   curl -X PATCH localhost:8080/api/notes/1 -d '{"pinned":true}'
--   curl -X DELETE localhost:8080/api/notes/1
--
-- One type declaration is the whole app: the fields define the schema, the
-- `service` block generates the REST endpoints, and the runtime serves them
-- from a single binary — no external database, no framework.

type Note {
  id:         Id
  title:      Text
  body:       Markdown
  pinned:     Bool = false                -- literal defaults populate on create
  created_at: Timestamp = now()           -- so does now(); computed defaults
                                          -- like words(...) are Stage 4+

  service rest "/api/notes"
    expose list, get, create, update, delete, subscribe
    -- list/get/create/update/delete work today (Stage 2).
    -- subscribe maps to GET /api/notes/live — a documented 501 stub
    -- until Stage 3 lands LIVE subscriptions over WebSocket.
}

-- A second actor that modifies Note. The closest thing to "another class" in
-- writeonce is another type with a trigger: there is no class/method model —
-- behavior attaches to data. Creating a Revision rewrites its target note's
-- title, inside the same transaction as the insert. Triggers execute from
-- Stage 4; today the block parses and is discarded.
type Revision {
  id:        Id
  note:      ref Note                     -- foreign key into Note
  new_title: Text
  at:        Timestamp = now()

  on create
    do update Note{ id == self.note }.title = self.new_title
}

-- Procedural entry point. Stage 2 parses and discards `main` blocks
-- (see crates/rt/src/parser.rs — skip_top_level_chunk); from Phase 6 on
-- this runs once at startup, before the HTTP server binds.
main {
  insert Note { title: "hello", body: "# First note" };

  -- A snapshot binding would never see later changes (let n = select ...).
  -- LIVE is the language's "pointer that observes stores": the handle
  -- receives a delta at every commit that touches a matching row. Stage 3.
  -- (Spec: docs/runtime/database/02-wo-language.md § Schema-Layer DML)
  let live = LIVE select Note{ title };

  -- The other actor fires: this insert runs Revision's on-create trigger,
  -- the trigger updates the note, and the commit pushes one delta.
  insert Revision { note: 1, new_title: "Hello World" };

  for delta in live {
    print(delta.kind, delta.row.title);   -- update "Hello World"
  }
}