-- Assessment engine: definitions (exam/capstone templates), cohort assignment, live sessions,
-- and the per-session scenario draw. exam_sessions (migration 006) is left untouched — it was
-- already scoped in Phase 2B as historical-import-only from the old Lab-local SQLite exam
-- bookkeeping, never the live mechanism. These tables ARE the live mechanism; duplicating
-- exam_sessions' purpose would mean building the real thing twice, so this doesn't reuse it.
--
-- Definitions are lightly versioned (a plain incrementing integer, not full history) so a
-- later edit to pool_spec/duration/hint_policy never changes what an already-started session is
-- graded against — every session snapshots the fields that matter at draw time.

CREATE TABLE IF NOT EXISTS assessment_definitions (
  assessment_definition_id  TEXT PRIMARY KEY,   -- slug, e.g. 'rootnode-capstone'
  type                       TEXT NOT NULL CHECK (type IN ('exam', 'capstone')),
  title                      TEXT NOT NULL,
  description                TEXT,
  duration_minutes           INTEGER NOT NULL,
  hint_policy                TEXT NOT NULL DEFAULT 'disabled' CHECK (hint_policy IN ('free', 'disabled', 'flagged')),
  pool_spec                  JSONB NOT NULL,     -- {"required": [scenario_id,...], "random": [{"count":n,"from":[scenario_id,...]},...]}
  completion_rule            JSONB NOT NULL DEFAULT '{"type":"all_scenarios_passed"}',
  unlock_rule                JSONB,              -- capstone only: {"type":"stages_complete","stage_ids":[...]}
  version                    INTEGER NOT NULL DEFAULT 1,
  status                     TEXT NOT NULL DEFAULT 'active' CHECK (status IN ('active', 'inactive')),
  created_by                 UUID REFERENCES instructors(instructor_id),
  created_at                 TIMESTAMPTZ NOT NULL DEFAULT now(),
  updated_at                 TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE TABLE IF NOT EXISTS assessment_cohort_assignments (
  assessment_definition_id  TEXT NOT NULL REFERENCES assessment_definitions(assessment_definition_id),
  cohort_id                  TEXT NOT NULL REFERENCES cohorts(cohort_id),
  assigned_by                UUID REFERENCES instructors(instructor_id),
  assigned_at                TIMESTAMPTZ NOT NULL DEFAULT now(),
  PRIMARY KEY (assessment_definition_id, cohort_id)
);

CREATE TABLE IF NOT EXISTS assessment_sessions (
  assessment_session_id     UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  assessment_definition_id  TEXT NOT NULL REFERENCES assessment_definitions(assessment_definition_id),
  definition_version         INTEGER NOT NULL,   -- snapshot: which version of the definition was drawn against
  student_id                 TEXT NOT NULL REFERENCES students(student_id),
  cohort_id                  TEXT,
  type                        TEXT NOT NULL,      -- snapshot
  title                       TEXT NOT NULL,      -- snapshot
  duration_minutes           INTEGER NOT NULL,    -- snapshot
  hint_policy                 TEXT NOT NULL,       -- snapshot
  status                      TEXT NOT NULL DEFAULT 'not_started'
                               CHECK (status IN ('not_started', 'in_progress', 'completed', 'expired', 'cancelled')),
  started_at                  TIMESTAMPTZ,
  expires_at                  TIMESTAMPTZ,         -- server-computed = started_at + duration_minutes; authoritative, never client-set
  submitted_at                TIMESTAMPTZ,
  random_seed                 TEXT,                -- recorded for audit/reproducibility, not exposed to the student before the draw
  result                      JSONB,               -- {"scenarios_total":n,"scenarios_passed":n,"passed":bool}
  created_at                  TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE TABLE IF NOT EXISTS assessment_session_scenarios (
  id                       BIGSERIAL PRIMARY KEY,
  assessment_session_id    UUID NOT NULL REFERENCES assessment_sessions(assessment_session_id),
  scenario_id               TEXT NOT NULL,
  position                  INTEGER NOT NULL,
  status                     TEXT NOT NULL DEFAULT 'pending' CHECK (status IN ('pending', 'in_progress', 'completed', 'failed')),
  attempt_id                 BIGINT REFERENCES scenario_attempts(attempt_id),
  UNIQUE (assessment_session_id, scenario_id)
);

DO $$ BEGIN
  ALTER TABLE scenario_attempts ADD CONSTRAINT scenario_attempts_assessment_session_fk
    FOREIGN KEY (assessment_session_id) REFERENCES assessment_sessions(assessment_session_id);
EXCEPTION
  WHEN duplicate_object THEN NULL;
END $$;

CREATE INDEX IF NOT EXISTS idx_assessment_sessions_student ON assessment_sessions(student_id, status);
CREATE INDEX IF NOT EXISTS idx_assessment_sessions_definition ON assessment_sessions(assessment_definition_id);
CREATE INDEX IF NOT EXISTS idx_assessment_session_scenarios_session ON assessment_session_scenarios(assessment_session_id);

-- Seed defaults — a working RootNode Capstone and one example exam ship out of the box, per the
-- Phase 3B spec ("ship with a sensible RootNode default"). Scenario ids are a snapshot of
-- scenarios/rootnode-path.json's stage lists as of this migration; edit the definition via the
-- admin API if curriculum content changes later, same as any other admin-owned config.
INSERT INTO assessment_definitions (assessment_definition_id, type, title, description, duration_minutes, hint_policy, pool_spec, completion_rule, unlock_rule)
VALUES (
  'rootnode-capstone', 'capstone', 'RootNode Capstone',
  'Combines skills from every curriculum stage into one operational assessment, weighted toward RootNode Real Ops incident scenarios. Evaluates operational ability, not memorized kubectl syntax.',
  90, 'flagged',
  '{"required": ["rootnode-runaway-monitor","broken-deployment","rootnode-probe-port-mismatch","rootnode-enforce-limits"], "random": [{"count":1,"from":["deploy-nginx","scale-deployment","rolling-update-task","liveness-probe-task","edit-deployment-basics"]},{"count":1,"from":["resource-limits-task","env-vars-configmap","secrets-basics"]},{"count":1,"from":["extract-logs-basics","kubectl-cp-basics","exec-command-basics","node-cordon-basics"]}]}',
  '{"type":"all_scenarios_passed"}',
  '{"type":"stages_complete","stage_ids":["foundation","workloads","networking","configuration","troubleshooting","real-ops"]}'
) ON CONFLICT (assessment_definition_id) DO NOTHING;

INSERT INTO assessment_definitions (assessment_definition_id, type, title, description, duration_minutes, hint_policy, pool_spec, completion_rule)
VALUES (
  'rootnode-quick-assessment', 'exam', 'RootNode Kubernetes Assessment',
  'A timed, randomized skills check drawn from across the curriculum. Example exam definition — instructors can create their own from the admin portal.',
  60, 'disabled',
  '{"required": [], "random": [{"count":2,"from":["deploy-nginx","scale-deployment","rolling-update-task","liveness-probe-task","daemonset-mcq"]},{"count":1,"from":["services-mcq","expose-service-basics"]},{"count":1,"from":["extract-logs-basics","kubectl-cp-basics","exec-command-basics","node-cordon-basics"]},{"count":1,"from":["rootnode-runaway-monitor","broken-deployment","rootnode-probe-port-mismatch","rootnode-enforce-limits"]}]}',
  '{"type":"all_scenarios_passed"}'
) ON CONFLICT (assessment_definition_id) DO NOTHING;