// Phase 5B — combines an enrollment row with real curriculum/progress/achievement state into
// one "program status" view: access/launch eligibility, stage/percent progress, and a
// deterministic next-activity (resume) target. Shared by the student self-paced routes and the
// admin program/enrollment routes so both surfaces show identical information computed one way,
// not two independently-maintained views that could drift.

const { deriveEnrollmentAccess, maybeCompleteEnrollment } = require('./enrollment');
const { computeCurriculumState } = require('./curriculum-rules');

async function buildProgramStatus(deps, enrollmentIn) {
  const { pool, curriculum, loadProgress } = deps;
  let enrollment = enrollmentIn;

  // Opportunistic, idempotent completion check (§10) — safe to run on every read; the
  // underlying UPDATE's `WHERE status = 'active'` guard makes a repeat call a no-op once an
  // enrollment is already completed, so this never double-fires or races itself.
  if (enrollment.status === 'active') {
    const completed = await maybeCompleteEnrollment(pool, enrollment.student_id, enrollment.program_id);
    if (completed.length) enrollment = { ...enrollment, ...completed[0] };
  }

  const access = deriveEnrollmentAccess(enrollment);
  // Only one curriculum path exists today (curriculum.js) — enrollment.curriculum_path is the
  // snapshot that would let a second path be resolved here later without touching this
  // function's shape; see docs/PHASE5B_SELF_PACED_ENROLLMENT.md §5.
  const path = curriculum.loadCurriculumPath();
  const progress = await loadProgress(pool, enrollment.student_id);

  const capstoneStatus = enrollment.status === 'completed' ? 'completed' : undefined;
  const state = path ? computeCurriculumState(path, progress, capstoneStatus) : null;

  let nextActivity = null;
  if (state) {
    const currentStage = state.stages.find((s) => s.id === state.current_stage);
    if (currentStage?.next_scenario) {
      nextActivity = { type: 'scenario', scenario_id: currentStage.next_scenario, stage_id: currentStage.id };
    } else if (state.capstone && state.capstone.status === 'unlocked') {
      nextActivity = { type: 'capstone', assessment_definition_id: state.capstone.assessment_definition_id };
    }
  }

  return {
    enrollment_id: enrollment.enrollment_id,
    program_id: enrollment.program_id,
    program_name: enrollment.program_name || null,
    program_family: enrollment.program_family || null,
    status: enrollment.status,
    effective_status: access.effective_status,
    can_launch: access.can_launch,
    blocked_reason: access.reason,
    delivery_mode: enrollment.delivery_mode,
    starts_at: enrollment.starts_at,
    access_ends_at: enrollment.access_ends_at,
    enrolled_at: enrollment.enrolled_at,
    activated_at: enrollment.activated_at,
    completed_at: enrollment.completed_at,
    cancelled_at: enrollment.cancelled_at,
    progress: state ? { percent_complete: state.percent_complete, current_stage: state.current_stage, stages: state.stages, capstone: state.capstone } : null,
    next_activity: nextActivity,
  };
}

module.exports = { buildProgramStatus };