-- environments — the disposable per-student lab registry.
-- See docs/LAB_ARCHITECTURE.md §3 and docs/PHASE1_PLATFORM_FOUNDATION.md §2.

DO $$ BEGIN
  CREATE TYPE environment_status AS ENUM (
    'requested', 'provisioning', 'running', 'resetting',
    'suspended',            -- experimental path only, see decision #3 / correction A
    'destroying', 'destroyed', 'error'
  );
EXCEPTION
  WHEN duplicate_object THEN NULL;
END $$;

CREATE TABLE IF NOT EXISTS environments (
  environment_id     UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  student_id          TEXT NOT NULL,        -- opaque external identifier (correction C) —
                                              -- no FK: students table isn't in this database
                                              -- until a later, separate Platform DB migration.
                                              -- The Provisioner trusts its caller on this value.
  lab_host_id         TEXT NOT NULL REFERENCES lab_hosts(lab_host_id),  -- real FK: both
                                              -- tables are Provisioner-owned Postgres.
  status              environment_status NOT NULL DEFAULT 'requested',
  routing_token       TEXT NOT NULL,         -- CSPRNG, opaque, unique
  container_id        TEXT,
  container_name      TEXT,
  network_id          TEXT,
  network_name        TEXT,
  network_subnet      CIDR,                  -- needed to install/remove the per-env firewall chain
  image_ref           TEXT NOT NULL,
  cpu_limit           NUMERIC NOT NULL,
  mem_limit_mb        INTEGER NOT NULL,
  pids_limit          INTEGER NOT NULL,
  storage_limit_mb    INTEGER NOT NULL,
  internal_ip         TEXT,
  internal_port        INTEGER NOT NULL DEFAULT 80,
  created_at           TIMESTAMPTZ NOT NULL DEFAULT now(),
  started_at           TIMESTAMPTZ,
  last_active_at       TIMESTAMPTZ,
  destroy_at            TIMESTAMPTZ,          -- idle-reaper's scheduled destroy time
  error_reason          TEXT
);

CREATE UNIQUE INDEX IF NOT EXISTS idx_environments_routing_token ON environments(routing_token);
CREATE INDEX IF NOT EXISTS idx_environments_student ON environments(student_id);
CREATE INDEX IF NOT EXISTS idx_environments_status ON environments(status);
CREATE INDEX IF NOT EXISTS idx_environments_lab_host ON environments(lab_host_id);

-- Phase 1 invariant "at most one non-terminal environment per student" is enforced in
-- application logic (lifecycle.js), not a DB constraint yet — a partial unique index is the
-- natural upgrade once this needs to be bulletproof under concurrent requests, not needed for
-- a single-instance provisioner in this phase.