import type { BackendContext } from '@jaspers-ai/sdk'
import { computeSummary, toOcc, type ChainMeta, type ChainRow } from './math.ts'
import { filterStrikesNearSpot } from './vendors.ts'

function parseNum(s: string | undefined): number | null {
  if (!s) return null
  const clean = s.replace(/[,%$]/g, '').trim()
  if (!clean || clean === '—' || clean === '-') return null
  const n = Number(clean)
  return Number.isFinite(n) ? n : null
}

function parseSide(cell: string) {
  const trimmed = cell.trim()
  if (!trimmed || trimmed === '—' || trimmed === '-') {
    return { last: null, bid: null, ask: null, vol: null, oi: null, iv: null, itm: false }
  }
  const itm = /\bITM\b/.test(trimmed)
  const clean = trimmed.replace(/\bITM\b/g, '').trim()
  const tokens = clean.split(/,\s+/)
  return {
    last: parseNum(tokens[0]),
    bid: parseNum(tokens[1]),
    ask: parseNum(tokens[2]),
    vol: parseNum(tokens[3]),
    oi: parseNum(tokens[4]),
    iv: parseNum(tokens[5]),
    itm,
  }
}

export async function fetchYahooChain(
  ctx: BackendContext,
  symbol: string,
  expiration: string | undefined,
  strikes: number,
): Promise<{ rows: ChainRow[]; meta: ChainMeta }> {
  const sym = symbol.toUpperCase().trim()
  // yfinance/server/get_options_chain takes `strikes` on each side of spot (up to 50 per side = 100 total).
  const eachSide = strikes <= 0 ? 50 : Math.min(Math.max(Math.ceil(strikes / 2) + 2, 5), 50)
  const optArgs: Record<string, unknown> = { symbol: sym, strikes: eachSide }
  if (expiration) optArgs.expiration = expiration

  const [optRes, quoteRes] = await Promise.all([
    ctx.tools.call('yfinance/server/get_options_chain', optArgs),
    ctx.tools.call('yfinance/server/get_quote', { symbols: [sym] }),
  ])

  let spot: number | null = null
  let change: number | null = null
  let changePct: number | null = null
  let dayRange: string | null = null
  let week52Range: string | null = null
  let volume: number | null = null

  if (!quoteRes.isError && quoteRes.text) {
    const qText = quoteRes.text
    const mPrice = qText.match(/:\s*([0-9.,]+)(?:,\s*([+-]?[0-9.,]+)\s*\(([+-]?[0-9.,]+)%\))?/)
    if (mPrice) {
      spot = parseNum(mPrice[1])
      change = parseNum(mPrice[2])
      changePct = parseNum(mPrice[3])
    }
    const mDay = qText.match(/Day\s+([0-9.,]+-[0-9.,]+)/)
    if (mDay) dayRange = mDay[1] ?? null
    const m52 = qText.match(/52-week range\s+([0-9.,]+-[0-9.,]+)/)
    if (m52) week52Range = m52[1] ?? null
    const mVol = qText.match(/Volume\s+([0-9.,]+)([KMB])?/)
    if (mVol) {
      const base = parseNum(mVol[1]) ?? 0
      const mult = mVol[2] === 'B' ? 1e9 : mVol[2] === 'M' ? 1e6 : mVol[2] === 'K' ? 1e3 : 1
      volume = Math.round(base * mult)
    }
  }

  if (optRes.isError && expiration) {
    // Fallback to nearest expiration if requested expiration was not in Yahoo's list
    const retry = await ctx.tools.call('yfinance/server/get_options_chain', { symbol: sym, strikes: eachSide })
    if (!retry.isError) return parseYahooText(sym, retry.text, spot, change, changePct, dayRange, week52Range, volume, strikes)
  }

  if (optRes.isError) {
    throw new Error(optRes.text || `Yahoo options lookup failed for ${sym}`)
  }

  return parseYahooText(sym, optRes.text, spot, change, changePct, dayRange, week52Range, volume, strikes)
}

function parseYahooText(
  sym: string,
  text: string,
  spotIn: number | null,
  changeIn: number | null,
  changePctIn: number | null,
  dayRange: string | null,
  week52Range: string | null,
  volume: number | null,
  maxStrikes: number,
): { rows: ChainRow[]; meta: ChainMeta } {
  const lines = text.split('\n').map((l) => l.trim()).filter(Boolean)
  let selectedExpiration: string | null = null
  let spot = spotIn
  let change = changeIn
  let changePct = changePctIn
  let expirations: string[] = []

  const headerLine = lines[0] ?? ''
  const mExp = headerLine.match(/expiring\s+(\d{4}-\d{2}-\d{2})/)
  if (mExp) selectedExpiration = mExp[1] ?? null
  const mUnd = headerLine.match(/Underlying\s+([0-9.,]+)(?:,\s*([+-]?[0-9.,]+)\s*\(([+-]?[0-9.,]+)%\))?/)
  if (mUnd) {
    if (spot == null) spot = parseNum(mUnd[1])
    if (change == null) change = parseNum(mUnd[2])
    if (changePct == null) changePct = parseNum(mUnd[3])
  }

  for (const line of lines) {
    if (line.startsWith('Expirations')) {
      const idx = line.indexOf(':')
      if (idx !== -1) {
        expirations = line
          .slice(idx + 1)
          .split(',')
          .map((s) => s.trim())
          .filter((s) => /^\d{4}-\d{2}-\d{2}$/.test(s))
      }
    }
  }

  const exp = selectedExpiration ?? expirations[0] ?? null
  const expStr = exp ?? ''
  const rows: ChainRow[] = []

  for (const line of lines) {
    if (!line.includes('|') || line.startsWith('strike |')) continue
    const parts = line.split('|').map((p) => p.trim())
    if (parts.length < 3) continue
    const strike = parseNum(parts[0])
    if (strike == null) continue
    const c = parseSide(parts[1] ?? '')
    const p = parseSide(parts[2] ?? '')
    const callContract = toOcc(sym, expStr, 'C', strike)
    const putContract = toOcc(sym, expStr, 'P', strike)
    rows.push({
      contract: `${callContract} / ${putContract}`,
      callContract,
      putContract,
      expiration: expStr,
      strike,
      callBid: c.bid,
      callAsk: c.ask,
      callLast: c.last,
      callChg: null,
      callVol: c.vol,
      callOi: c.oi,
      callIv: c.iv,
      callDelta: null,
      callItm: c.itm || (spot != null ? strike < spot : false),
      putBid: p.bid,
      putAsk: p.ask,
      putLast: p.last,
      putChg: null,
      putVol: p.vol,
      putOi: p.oi,
      putIv: p.iv,
      putDelta: null,
      putItm: p.itm || (spot != null ? strike > spot : false),
    })
  }

  const filtered = filterStrikesNearSpot(rows, spot, maxStrikes)
  return computeSummary(filtered, {
    symbol: sym,
    provider: 'yahoo',
    feedLabel: 'Yahoo Finance (Delayed)',
    spot,
    change,
    changePct,
    dayRange,
    week52Range,
    volume,
    expirations,
    selectedExpiration: exp,
  })
}