#!/usr/bin/env node
// Phase 6C §24 — programmatic content validation: fails loudly if the course/module/activity
// content model has any structural defect. Run against a live Postgres (same connection the
// Platform API uses) plus the repo's own scenarios/data, scenarios/rootnode-path.json, and
// content/root/ files — cross-checks the database against the filesystem rather than trusting
// either alone. Exit code 1 on any failure; safe to wire into CI later, not built as CI here
// (no CI system exists in this repo to wire into).
//
// Usage: PLATFORM_DB_URL=postgres://postgres:postgres@localhost:5433/rootnode_platform \
//   node infra/scripts/validate-course-content.js

const fs = require('fs');
const path = require('path');
const REPO_ROOT = path.join(__dirname, '../..');
// Reuses platform/api's own `pg` dependency rather than adding a new package.json/node_modules
// just for this script — same "no new dependency where an existing one already covers it"
// convention the rest of this codebase follows.
const { Client } = require(path.join(REPO_ROOT, 'platform/api/node_modules/pg'));
const DB_URL = process.env.PLATFORM_DB_URL || 'postgres://postgres:postgres@localhost:5433/rootnode_platform';

let errors = 0;
function fail(msg) { console.error(`  FAIL — ${msg}`); errors++; }
function ok(msg) { console.log(`  ok — ${msg}`); }

async function main() {
  const client = new Client({ connectionString: DB_URL });
  await client.connect();

  const scenarioIds = new Set(fs.readdirSync(path.join(REPO_ROOT, 'scenarios/data')).filter((f) => f.endsWith('.json')).map((f) => f.replace('.json', '')));
  const assessmentIds = new Set((await client.query('SELECT assessment_definition_id FROM assessment_definitions')).rows.map((r) => r.assessment_definition_id));
  const courses = (await client.query('SELECT * FROM courses')).rows;
  const modules = (await client.query('SELECT * FROM course_modules')).rows;
  const activities = (await client.query('SELECT * FROM module_activities')).rows;

  const courseIds = new Set(courses.map((c) => c.course_id));
  const moduleIds = new Set(modules.map((m) => m.module_id));
  const activityIds = new Set(activities.map((a) => a.activity_id));

  console.log(`Loaded ${courses.length} courses, ${modules.length} modules, ${activities.length} activities, ${scenarioIds.size} scenario files.\n`);

  // ── No duplicate IDs (PK already enforces this at the DB level, but verify the exported
  // JS-level arrays too, catching an accidental cross-table id collision the DB doesn't check) ─
  for (const [label, ids] of [['course', courses.map((c) => c.course_id)], ['module', modules.map((m) => m.module_id)], ['activity', activities.map((a) => a.activity_id)]]) {
    const seen = new Set(); const dupes = new Set();
    for (const id of ids) { if (seen.has(id)) dupes.add(id); seen.add(id); }
    if (dupes.size) fail(`duplicate ${label} id(s): ${[...dupes].join(', ')}`); else ok(`no duplicate ${label} ids`);
  }

  // ── No orphan modules/activities (referencing a course/module that doesn't exist) ────────
  const orphanModules = modules.filter((m) => !courseIds.has(m.course_id));
  if (orphanModules.length) fail(`orphan module(s) referencing a missing course: ${orphanModules.map((m) => m.module_id).join(', ')}`); else ok('no orphan modules');
  const orphanActivities = activities.filter((a) => !moduleIds.has(a.module_id));
  if (orphanActivities.length) fail(`orphan activity(ies) referencing a missing module: ${orphanActivities.map((a) => a.activity_id).join(', ')}`); else ok('no orphan activities');

  // ── No invalid scenario/assessment references ────────────────────────────────────────────
  const badScenarioRefs = activities.filter((a) => a.scenario_id && !scenarioIds.has(a.scenario_id));
  if (badScenarioRefs.length) fail(`activity(ies) referencing a missing scenario file: ${badScenarioRefs.map((a) => `${a.activity_id}->${a.scenario_id}`).join(', ')}`); else ok('every lab activity scenario_id resolves to a real scenario file');
  const badAssessmentRefs = activities.filter((a) => a.assessment_definition_id && !assessmentIds.has(a.assessment_definition_id));
  if (badAssessmentRefs.length) fail(`activity(ies) referencing a missing assessment_definition: ${badAssessmentRefs.map((a) => `${a.activity_id}->${a.assessment_definition_id}`).join(', ')}`); else ok('every assessment/capstone activity resolves to a real assessment_definition');

  // ── No impossible prerequisite references (a module/course pointing at an id that doesn't
  // exist at all — distinct from Phase 6A's deliberate "PLANNED = vacuously satisfied" rule,
  // this catches a genuine TYPO in a prerequisite id) ──────────────────────────────────────
  for (const c of courses) {
    for (const prereq of c.prerequisites || []) {
      if (!courseIds.has(prereq)) fail(`course ${c.course_id} lists a prerequisite that doesn't exist: ${prereq}`);
    }
  }
  for (const m of modules) {
    for (const prereq of m.prerequisites || []) {
      if (!moduleIds.has(prereq)) fail(`module ${m.module_id} lists a prerequisite that doesn't exist: ${prereq}`);
    }
  }
  ok('every course/module prerequisite id resolves to a real course/module (or was already reported above)');

  // ── No course-tree cycles (a module/course that is its own transitive prerequisite) ──────
  function hasCycle(items, idKey) {
    const byId = new Map(items.map((i) => [i[idKey], i]));
    const state = new Map(); // id -> 'visiting' | 'done'
    let cyclic = null;
    function visit(id, chain) {
      if (cyclic) return;
      const item = byId.get(id);
      if (!item) return;
      if (state.get(id) === 'visiting') { cyclic = [...chain, id]; return; }
      if (state.get(id) === 'done') return;
      state.set(id, 'visiting');
      for (const prereq of item.prerequisites || []) visit(prereq, [...chain, id]);
      state.set(id, 'done');
    }
    for (const item of items) visit(item[idKey], []);
    return cyclic;
  }
  const courseCycle = hasCycle(courses, 'course_id');
  if (courseCycle) fail(`course prerequisite cycle: ${courseCycle.join(' -> ')}`); else ok('no course prerequisite cycles');
  const moduleCycle = hasCycle(modules, 'module_id');
  if (moduleCycle) fail(`module prerequisite cycle: ${moduleCycle.join(' -> ')}`); else ok('no module prerequisite cycles');

  // ── No sequence collisions within one module/course (two siblings sharing a sequence
  // number is a real authoring bug — found and fixed once already in Phase 6B, see
  // 023_phase6b_curriculum.sql's ROOT 07 m02/m04 comment) ──────────────────────────────────
  function checkSequenceCollisions(items, groupKey, label) {
    const groups = new Map();
    for (const item of items) {
      const key = item[groupKey];
      if (!groups.has(key)) groups.set(key, []);
      groups.get(key).push(item.sequence);
    }
    let collided = 0;
    for (const [key, seqs] of groups) {
      const dupes = seqs.filter((s, i) => seqs.indexOf(s) !== i);
      if (dupes.length) { fail(`${label} sequence collision in ${key}: sequence ${[...new Set(dupes)].join(',')} used more than once`); collided++; }
    }
    if (!collided) ok(`no ${label} sequence collisions`);
  }
  checkSequenceCollisions(modules, 'course_id', 'module');
  checkSequenceCollisions(activities, 'module_id', 'activity');

  // ── Instructor notes never leak to students (content.js's own splitContent, exercised
  // directly here rather than trusted). content.js resolves content_path against
  // CONTENT_ROOT_DIR if set, defaulting to one level up from its own src/ (correct only INSIDE
  // the Docker image, where the Dockerfile COPYs content/ next to src/) — running it directly
  // on the host here needs this override so it resolves against the real repo root instead.
  process.env.CONTENT_ROOT_DIR = REPO_ROOT;
  const { loadContent } = require(path.join(REPO_ROOT, 'platform/api/src/content.js'));
  let leakChecked = 0, leaked = 0;
  for (const a of activities) {
    if (!a.content_path) continue;
    const c = loadContent(a.content_path);
    leakChecked++;
    if (c && c.shared && c.shared.includes('## Instructor Notes')) { fail(`${a.activity_id}: 'shared' (student-visible) content still contains the Instructor Notes heading — split failed`); leaked++; }
  }
  if (!leaked) ok(`instructor notes correctly excluded from student-visible content in all ${leakChecked} activities with a content_path`);

  // ── No content_path referencing a missing file ───────────────────────────────────────────
  let missingContent = 0;
  for (const a of activities) {
    if (!a.content_path) continue;
    if (!fs.existsSync(path.join(REPO_ROOT, a.content_path))) { fail(`${a.activity_id}: content_path does not exist on disk: ${a.content_path}`); missingContent++; }
  }
  if (!missingContent) ok('every content_path resolves to a real file on disk');

  // ── A 'lab' activity must have a scenario_id; an 'assessment'/'capstone' must have an
  // assessment_definition_id (the DB CHECK constraints already enforce this — verified here
  // too so this script fails loudly even against a hand-edited row that somehow bypassed it) ─
  const labsMissingScenario = activities.filter((a) => a.activity_type === 'lab' && !a.scenario_id);
  if (labsMissingScenario.length) fail(`lab activity(ies) with no scenario_id: ${labsMissingScenario.map((a) => a.activity_id).join(', ')}`); else ok('every lab activity has a scenario_id');
  const assessmentsMissingDef = activities.filter((a) => ['assessment', 'capstone'].includes(a.activity_type) && !a.assessment_definition_id);
  if (assessmentsMissingDef.length) fail(`assessment/capstone activity(ies) with no assessment_definition_id: ${assessmentsMissingDef.map((a) => a.activity_id).join(', ')}`); else ok('every assessment/capstone activity has an assessment_definition_id');

  // ── Section 16/17 — a module marked READY (self-paced-sufficient) must not defer explanation
  // to a live instructor in its student-visible content. Scans the actual 'shared' half of
  // content.js's real split (never the instructor-notes half, which is explicitly ALLOWED to
  // say "explain live"), and only against READY modules — instructor-led-only PARTIAL modules
  // (see docs/ROOT_PILOT_CURRICULUM.md) are not held to the self-paced bar. ───────────────────
  const readyModuleIds = new Set(modules.filter((m) => m.status === 'ready').map((m) => m.module_id));
  const deferralPhrases = [/your instructor will explain/i, /ask your instructor/i, /your instructor will cover/i];
  let deferralsFound = 0;
  for (const a of activities) {
    if (!a.content_path || !readyModuleIds.has(a.module_id)) continue;
    const c = loadContent(a.content_path);
    if (!c || !c.shared) continue;
    if (deferralPhrases.some((re) => re.test(c.shared))) { fail(`${a.activity_id}: self-paced-marked module's student-visible content defers to a live instructor`); deferralsFound++; }
  }
  if (!deferralsFound) ok('no READY module\'s student-visible content defers explanation to a live instructor');

  // ── Duplicate scenario mapping — flagged, not failed, since Phase 6A/6B both document
  // DELIBERATE reuse (rootnode-probe-port-mismatch in both the gold module and Real Ops;
  // pod-security-context/rbac-clusterrole as documented independent-practice duplicates). This
  // prints the list for a human to confirm against docs/ROOT_CURRICULUM_COVERAGE_MATRIX.md's
  // 'duplicate concepts identified' section rather than failing the build. ───────────────────
  const scenarioUsage = new Map();
  for (const a of activities) {
    if (!a.scenario_id) continue;
    if (!scenarioUsage.has(a.scenario_id)) scenarioUsage.set(a.scenario_id, []);
    scenarioUsage.get(a.scenario_id).push(a.activity_id);
  }
  const reused = [...scenarioUsage.entries()].filter(([, ids]) => ids.length > 1);
  console.log(`  info — ${reused.length} scenario(s) intentionally reused across multiple activities (see docs/ROOT_CURRICULUM_COVERAGE_MATRIX.md):`);
  for (const [sid, ids] of reused) console.log(`         ${sid}: ${ids.join(', ')}`);

  await client.end();

  console.log(`\n${errors === 0 ? 'PASS' : 'FAIL'} — ${errors} error(s)`);
  process.exit(errors ? 1 : 0);
}

main().catch((e) => { console.error('FATAL', e); process.exit(1); });