import type { AIProvider } from '@/lib/ai/types'
import { extractSourceAssets } from '@/lib/ai/services/slide-source-assets'
import {
  validateInteractiveDemo,
  type InteractiveDemoV1,
} from '@/lib/interactive-demo'
import {
  validateInteractivePage,
  type PageSpecV1,
  type PageValidationIssue,
} from '@/lib/interactive-page'
import { normalizeInteractivePageCandidate } from '@/lib/interactive-page/normalize'

function stripToPlain(html: string): string {
  return html
    .replace(/<[^>]+>/g, ' ')
    .replace(/&nbsp;/g, ' ')
    .replace(/&amp;/g, '&')
    .replace(/&lt;/g, '<')
    .replace(/&gt;/g, '>')
    .replace(/&quot;/g, '"')
    .replace(/&#39;/g, "'")
    .replace(/\s+/g, ' ')
    .trim()
}

function slugId(title: string): string {
  const s = title
    .toLowerCase()
    .normalize('NFD')
    .replace(/[\u0300-\u036f]/g, '')
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/^-|-$/g, '')
    .slice(0, 40)
  return s ? `page.${s}` : 'page.generated'
}

function firstSentence(text: string, max = 100): string {
  const s = text.split(/[.!?。]/)[0]?.trim() || text.trim()
  return s.slice(0, max) || 'Page interactive'
}

function chunkSentences(text: string): string[] {
  return text
    .split(/(?<=[.!?。])\s+/)
    .map((s) => s.trim())
    .filter((s) => s.length > 20)
}



export function buildPageFromNote(
  content: string,
  lang: string,
  assets: ReturnType<typeof extractSourceAssets>
): Record<string, unknown> {
  const plain = stripToPlain(content)
  const sentences = [
    ...assets.keySentences,
    ...chunkSentences(plain),
  ].filter((s, i, arr) => arr.indexOf(s) === i)
  const title = firstSentence(sentences[0] || plain, 90)
  const lead = sentences[0]?.slice(0, 320) || plain.slice(0, 320) || title
  const fr = lang.startsWith('fr')
  // Displayable formulas only (KaTeX eats spaces — no prose, bounded length)
  const displayFormulas = assets.formulas.filter((f) => f.length <= 120)
  const formula = displayFormulas[0]
  const formula2 = displayFormulas[1]

  const cards = [
    {
      badge: 'PROBLEM',
      title: fr ? 'Contexte' : 'Context',
      body: (sentences[0] || lead).slice(0, 160),
      intent: 'warning' as const,
    },
    {
      badge: 'APPROACH',
      title: fr ? 'Approche' : 'Approach',
      body: (sentences[1] || sentences[0] || lead).slice(0, 160),
      intent: 'flow' as const,
    },
    {
      badge: 'RESULT',
      title: formula ? (fr ? 'Relation' : 'Relation') : fr ? 'Idée clé' : 'Key idea',
      body: formula ? `$${formula}$` : (sentences[2] || lead).slice(0, 160),
      intent: 'output' as const,
    },
  ]

  const sections: Record<string, unknown>[] = [
    {
      id: 's1',
      title: fr ? 'Le problème' : 'The problem',
      blocks: [
        { type: 'prose', md: sentences[0] || lead },
        {
          type: 'callout',
          kind: 'definition',
          title: fr ? 'En bref' : 'In short',
          md: (sentences[1] || plain.slice(0, 180) || title).slice(0, 220),
        },
      ],
    },
    {
      id: 's2',
      title: fr ? 'Mécanisme' : 'Mechanism',
      blocks: [
        { type: 'prose', md: sentences[1] || sentences[0] || lead },
        ...(formula ? [{ type: 'formula', tex: formula }] : []),
        ...(formula2
          ? [
              {
                type: 'callout',
                kind: 'tip',
                title: fr ? 'Aussi' : 'Also',
                md: `$${formula2}$`,
              },
            ]
          : []),
      ],
    },
    {
      id: 's3',
      title: fr ? 'Synthèse' : 'Synthesis',
      blocks: [
        {
          type: 'prose',
          md:
            sentences[2] ||
            (fr
              ? 'Retenez le mécanisme — la démo interactive en retrace le flux.'
              : 'Keep the mechanism — the interactive demo traces the flow.'),
        },
        {
          type: 'stats',
          items: [
            {
              value: String(Math.max(assets.formulas.length, 1)),
              label: fr ? 'Formules' : 'Formulas',
            },
            {
              value: String(Math.min(Math.max(sentences.length, 3), 8)),
              label: fr ? 'Idées' : 'Ideas',
            },
            assets.numbers[0]
              ? {
                  value: String(assets.numbers[0].value),
                  label: assets.numbers[0].label || (fr ? 'Donnée' : 'Figure'),
                }
              : { value: '→', label: fr ? 'Suite' : 'Next' },
          ],
        },
      ],
    },
  ]

  return {
    schemaVersion: 1,
    id: slugId(title),
    lang,
    hero: {
      kicker: fr ? 'EXPLAINER INTERACTIF' : 'INTERACTIVE EXPLAINER',
      title,
      subtitle: (sentences[1] || plain).slice(0, 140),
      meta: fr ? 'Généré depuis votre note' : 'Generated from your note',
    },
    overview: { lead, cards },
    sections,
  }
}

function injectDemo(
  page: Record<string, unknown>,
  block: Record<string, unknown>
): Record<string, unknown> {
  const sections = Array.isArray(page.sections)
    ? ([...page.sections] as Record<string, unknown>[])
    : []
  if (!sections.length) return page
  const targetIdx = Math.min(1, sections.length - 1)
  const target = { ...sections[targetIdx] }
  const blocks = Array.isArray(target.blocks)
    ? [...(target.blocks as Record<string, unknown>[])]
    : []
  blocks.push(block)
  target.blocks = blocks
  sections[targetIdx] = target
  return { ...page, sections }
}

export type GenerateInteractivePageInput = {
  content: string
  lang?: string
  /** Kept for API compatibility — page skeleton no longer depends on LLM. */
  provider: AIProvider
}

export type GenerateInteractivePageResult =
  | { ok: true; page: PageSpecV1; attempts: number }
  | {
      ok: false
      issues?: PageValidationIssue[]
      error?: string
      reason?: string
      raw?: string
      attempts: number
    }

/**
 * Deterministic step-by-step block from extracted formulas (math notes).
 * Replaces the old generic box-diagram fallback — boxes are banned.
 */
function buildDeterministicSteps(
  content: string,
  lang: string,
  assets: ReturnType<typeof extractSourceAssets>
): Record<string, unknown> | null {
  const fr = lang.startsWith('fr')
  const formulas = assets.formulas.filter((f) => f.length <= 120).slice(0, 6)
  if (formulas.length < 3) return null
  const plain = stripToPlain(content)
  const sentences = [
    ...assets.keySentences,
    ...chunkSentences(plain),
  ].filter((s, i, a) => a.indexOf(s) === i)
  return {
    type: 'steps',
    title: fr ? 'Dérivation pas à pas' : 'Step-by-step derivation',
    steps: formulas.map((tex, i) => ({
      tex,
      ...(i === 0
        ? { rule: fr ? 'Point de départ' : 'Starting point' }
        : {}),
      speak:
        sentences[i]?.slice(0, 120) ||
        (fr ? `Étape **${i + 1}** de la dérivation.` : `Step **${i + 1}** of the derivation.`),
    })),
    caption: fr
      ? 'Formules extraites de la note, déroulées pas à pas.'
      : 'Formulas extracted from the note, walked through step by step.',
  }
}

/**
 * Instant reliable page: deterministic skeleton + deterministic steps (math)
 * or Play/Step demo (other content). No LLM round-trip for the page itself.
 */
export async function generateInteractivePageFromContent(
  input: GenerateInteractivePageInput
): Promise<GenerateInteractivePageResult> {
  const lang = input.lang || 'fr'
  const assets = extractSourceAssets(input.content)
  const plain = stripToPlain(input.content)
  if (plain.split(/\s+/).filter(Boolean).length < 30) {
    return {
      ok: false,
      error: 'unsuitable_content',
      reason: 'Contenu trop court pour une page interactive',
      attempts: 0,
    }
  }

  let pageObj = buildPageFromNote(input.content, lang, assets)
  const stepsBlock = buildDeterministicSteps(input.content, lang, assets)
  if (stepsBlock) {
    pageObj = injectDemo(pageObj, stepsBlock)
  }

  const normalized = normalizeInteractivePageCandidate(pageObj, lang)
  if (!normalized) {
    return {
      ok: false,
      error: 'normalize_failed',
      reason: 'Impossible de normaliser la page',
      attempts: 1,
    }
  }

  const result = validateInteractivePage(normalized)
  if (!result.ok) {
    // Last resort: page without demo
    const sections = Array.isArray(normalized.sections)
      ? (normalized.sections as Record<string, unknown>[]).map((sec) => ({
          ...sec,
          blocks: Array.isArray(sec.blocks)
            ? (sec.blocks as Record<string, unknown>[]).filter(
                (b) => b.type !== 'demo'
              )
            : [],
        }))
      : []
    const stripped = validateInteractivePage({ ...normalized, sections })
    if (stripped.ok) {
      return { ok: true, page: stripped.page, attempts: 1 }
    }
    return {
      ok: false,
      issues: result.issues,
      error: 'validation_failed',
      reason: result.issues[0]
        ? `${result.issues[0].path}: ${result.issues[0].message}`
        : 'Page invalide',
      attempts: 1,
    }
  }

  return { ok: true, page: result.page, attempts: 1 }
}