-- ImageHub: per-file work TASKS that flow through a dataset's pipeline stages (single-user MVP).
-- A task is a NEW join row (one per dataset file) carrying its pipeline position (current_stage_id
-- + pipeline_state), per-user queue status, assignee, priority, and the Ground-Truth reference flag.
-- The file row itself (imagehub_dataset_files) stays a pure storage record. Membership / multi-labeler
-- assignment is a later phase, so for now task access reuses the dataset owner-or-admin gate.
-- Idempotent (CREATE ... IF NOT EXISTS) so the startup runner can apply it to volumes that predate it.
-- Apply after 020 (no semicolons inside comments or string literals — the runner splitter is naive):
--   docker exec -i initiative-postgres psql -U initiative -d initiatives < be0/migrations/021_imagehub_task_pipeline.sql

CREATE TABLE IF NOT EXISTS imagehub_tasks (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  dataset_id UUID NOT NULL REFERENCES imagehub_datasets(id) ON DELETE CASCADE,
  dataset_file_id UUID NOT NULL REFERENCES imagehub_dataset_files(id) ON DELETE CASCADE,
  name TEXT NOT NULL DEFAULT '',
  current_stage_id UUID REFERENCES imagehub_dataset_stages(id) ON DELETE SET NULL,
  pipeline_state TEXT NOT NULL DEFAULT 'inLabel' CHECK (pipeline_state IN ('inLabel','inReview','groundTruth','issue')),
  queue_status TEXT NOT NULL DEFAULT 'assigned' CHECK (queue_status IN ('assigned','saved','pendingFinalization','skipped')),
  assignee_user_id UUID REFERENCES users(id) ON DELETE SET NULL,
  assignment_mode TEXT NOT NULL DEFAULT 'auto' CHECK (assignment_mode IN ('auto','manual')),
  priority DOUBLE PRECISION NOT NULL DEFAULT 0 CHECK (priority >= 0 AND priority <= 1),
  is_reference_standard BOOLEAN NOT NULL DEFAULT FALSE,
  skipped_seq BIGINT,
  created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
  updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
);

-- One task per file (MVP simplification — droppable later for multi-task-per-file).
CREATE UNIQUE INDEX IF NOT EXISTS uq_imagehub_tasks_file
  ON imagehub_tasks (dataset_file_id);

-- Queue scan: a dataset's tasks at a given stage and status, highest priority first.
CREATE INDEX IF NOT EXISTS idx_imagehub_tasks_queue
  ON imagehub_tasks (dataset_id, current_stage_id, queue_status, priority DESC);

-- A user's personal labeling queue across datasets.
CREATE INDEX IF NOT EXISTS idx_imagehub_tasks_assignee
  ON imagehub_tasks (assignee_user_id, queue_status);