import { createContext, useCallback, useContext, useEffect, useMemo, useRef, useState } from 'react'
import { useZino } from './provider.jsx'
import { RV_LEADS, STAGES, phaseOf } from './config.js'

/**
 * The whole book, fetched ONCE and shared.
 *
 * The sidebar used to carry no counts, on the reasoning that a tally could only
 * come from a second full list call that would then disagree with the queue's
 * own total. That reasoning was right about the cost and wrong about the
 * conclusion: a sidebar with no numbers means the only way to learn whether
 * anything is waiting on you is to click all nine queues, which is the one
 * question a console's navigation exists to answer.
 *
 * So there is no second call. The overview already fetched the whole book on a
 * timer; that fetch moves here and both surfaces read it, which is one call
 * fewer than before and makes the two agree by construction.
 *
 * Bounded at 200 rows, as the overview always was. Beyond that the honest
 * answer is an aggregate endpoint rather than a bigger limit, and the counts
 * would need to say they are partial — worth knowing before this app meets a
 * real book.
 */

const PortfolioContext = createContext(null)
const EMPTY = []

export function PortfolioProvider({ children }) {
  const { client, user } = useZino()
  // Identity, not just presence: switching user must not show the previous
  // one's book while the new fetch is in flight.
  const who = user?.id ?? user?.email ?? null
  // Seeded from `who` rather than set inside the effect. Nothing here writes
  // state synchronously during a render pass — a signed-out shell is 'ready'
  // and empty from the first frame, and the first fetch only ever moves it
  // forwards, so there is no loading flash and no cascading render.
  const [state, setState] = useState(() => ({
    status: who ? 'loading' : 'ready', rows: EMPTY, at: null, error: null,
  }))
  const cancelled = useRef(false)

  const load = useCallback(() => {
    if (!who) return Promise.resolve()
    return client.recordView(RV_LEADS, { limit: 200 })
      .then((res) => {
        if (cancelled.current) return
        setState({ status: 'ready', rows: res?.data ?? res?.rows ?? res?.records ?? EMPTY, at: new Date(), error: null })
      })
      .catch((err) => {
        if (cancelled.current) return
        // A failed poll leaves a good book on screen. Only a first load is an error.
        setState((p) => (p.status === 'ready' ? p : { status: 'error', rows: EMPTY, at: null, error: err }))
      })
  }, [client, who])

  useEffect(() => {
    cancelled.current = false
    load()
    const id = setInterval(() => { if (document.visibilityState === 'visible') load() }, 30000)
    return () => { cancelled.current = true; clearInterval(id) }
  }, [load])

  const value = useMemo(() => ({ ...state, reload: load }), [state, load])
  return <PortfolioContext.Provider value={value}>{children}</PortfolioContext.Provider>
}

export function usePortfolio() {
  const ctx = useContext(PortfolioContext)
  if (!ctx) throw new Error('usePortfolio must be used inside PortfolioProvider')
  return ctx
}

const DAY = 86400000
const daysToExpiry = (v) => {
  if (!v) return null
  const d = Date.parse(String(v).substring(0, 10) + 'T00:00:00Z')
  return isNaN(d) ? null : Math.round((d - Date.parse(new Date().toISOString().substring(0, 10) + 'T00:00:00Z')) / DAY)
}

/**
 * Per-stage tallies for the sidebar.
 *
 * `waiting` is the number that goes on the badge: leads whose PHASE still needs
 * a person. `working` is the rest — in the state, carried by an agent, not
 * anyone's task. Badging the state total told an operator four leads needed
 * them when two did, which is how a queue stops being believed.
 *
 * `urgent` marks a queue holding a renewal that has lapsed or expires within a
 * week. It is the only reason to look at one queue before another, and it was
 * invisible until you opened each one.
 */
export function useStageCounts() {
  const { rows, status } = usePortfolio()
  return useMemo(() => {
    const out = {}
    for (const s of STAGES) out[s.uid] = { total: 0, waiting: 0, working: 0, urgent: 0 }
    for (const r of rows) {
      const s = STAGES.find((x) => x.name === r.current_state_name)
      if (!s) continue
      const t = out[s.uid]
      t.total += 1
      if (s.kind !== 'end' && phaseOf(s, r).kind === 'auto') t.working += 1
      else if (s.kind !== 'end') t.waiting += 1
      const d = daysToExpiry(r.renewal_due_date)
      if (s.kind !== 'end' && d !== null && d <= 7) t.urgent += 1
    }
    return { counts: out, ready: status === 'ready' }
  }, [rows, status])
}