import { useState, useEffect, useCallback } from 'react'
import ReactMarkdown from 'react-markdown'
import remarkGfm from 'remark-gfm'
import styles from './ScenarioPanel.module.css'

// Phase 3B progressive hints — used when the Gateway has stripped the full `hints` array from
// the scenario payload (the multi-student, Platform-mediated deployment; see
// platform/gateway/src/server.js's GET /lab/:token/api/scenarios/:scenarioId). Hints are
// fetched one at a time from the Platform API, server-enforced sequential (can't skip to hint
// 3), and every reveal is recorded against the student's attempt — none of that is possible
// with the old fully-preloaded array this replaces for this deployment mode.
//
// In standalone/single-container dev mode there's no Gateway rewrite, so `scenario.hints` is
// still the full array and ScenarioPanel never renders this component at all — see the
// `hintCount != null` check at the call site.
export default function ProgressiveHints({ scenarioId, totalHints }) {
  const [revealed, setRevealed] = useState([]) // [{level, title, body, command}]
  const [loading, setLoading] = useState(false)
  const [error, setError] = useState(null)
  const [copiedIdx, setCopiedIdx] = useState(null)
  const [assessmentHintPolicy, setAssessmentHintPolicy] = useState(null) // null = not in an assessment; 'free'|'disabled'|'flagged'

  // A scenario/environment change resets local reveal state — the server is still the source
  // of truth (GET /attempt would show the real highest_hint_level), this is just what's
  // rendered locally this session. Also checks whether this scenario is part of an active
  // Platform assessment, purely to show the policy indicator pre-emptively (the server enforces
  // the policy regardless, on every reveal call — this is UX, not the security boundary).
  useEffect(() => {
    setRevealed([]); setError(null); setAssessmentHintPolicy(null)
    fetch('/api/assessments/active').then((r) => r.json()).then((d) => {
      if (d.active && d.scenarios?.some((s) => s.scenario_id === scenarioId)) setAssessmentHintPolicy(d.hint_policy)
    }).catch(() => {})
  }, [scenarioId])

  const revealNext = useCallback(async () => {
    setLoading(true); setError(null)
    try {
      const r = await fetch(`api/scenarios/${scenarioId}/hint`, { method: 'POST' })
      const d = await r.json()
      if (!r.ok) { setError(d.message || d.error || 'Could not reveal a hint.'); return }
      setRevealed((h) => [...h, { level: d.level, ...d.hint }])
    } catch {
      setError('Could not reach the platform to reveal a hint.')
    } finally {
      setLoading(false)
    }
  }, [scenarioId])

  function copyCmd(cmd, idx) {
    if (navigator.clipboard && window.isSecureContext) {
      navigator.clipboard.writeText(cmd).then(() => { setCopiedIdx(idx); setTimeout(() => setCopiedIdx(null), 1800) })
    }
  }

  if (totalHints === 0) return <div className={styles.noHints}>No hints available for this scenario.</div>

  if (assessmentHintPolicy === 'disabled' && revealed.length === 0) {
    return <div className={styles.noHints}>Hints Disabled — this assessment does not allow hints.</div>
  }

  return (
    <div>
      {assessmentHintPolicy === 'flagged' && <div className={styles.setupNote} style={{ marginBottom: '0.75rem' }}>Using a hint will be recorded.</div>}
      {revealed.map((hint, i) => (
        <div key={i} className={styles.hintCard}>
          <div className={styles.hintHeader}>
            <div className={styles.hintLeft}>
              <span className={styles.hintNum}>Hint {hint.level}</span>
              <span className={styles.hintTitle}>{hint.title}</span>
            </div>
          </div>
          <div className={styles.hintBody}>
            <p className={styles.hintText}><ReactMarkdown remarkPlugins={[remarkGfm]}>{hint.body}</ReactMarkdown></p>
            {hint.command && (
              <div className={styles.cmdBlock}>
                <pre className={styles.cmdPre}>{hint.command}</pre>
                <button className={styles.copyBtn} onClick={() => copyCmd(hint.command, i)}>{copiedIdx === i ? '✓ Copied' : 'Copy'}</button>
              </div>
            )}
          </div>
        </div>
      ))}
      {error && <div className={styles.validateError}>⚠ {error}</div>}
      {revealed.length < totalHints && (
        <button className={styles.setupBtn} disabled={loading} onClick={revealNext}>
          {loading ? 'Revealing…' : `Reveal Hint ${revealed.length + 1} of ${totalHints}`}
        </button>
      )}
    </div>
  )
}