import { useCallback, useEffect, useState } from 'react'
import { Link } from 'react-router-dom'
import { api } from '../api/client.js'
import { useAuth } from '../contexts/AuthContext.jsx'

// Core's per-Team notification control, rendered into a THIRD slot a module
// declares (TEAMS.md §6.3, phase 6).
//
// **Why this is a slot at all, and why it is the third one.** Teams have no core
// page — the module that owns the vocabulary owns the page — so a control that
// acts on one Team has nowhere of core's to live. The feed and the forum go below
// the module's roster; this goes above it, because muting a guild is an action ON
// the page rather than more content in it, and that is exactly the placement
// decision a module cannot make if core stacks everything into one fill.
//
// **It renders nothing for a viewer who is not in the Team**, including anonymous
// ones, and that is a privacy property rather than a tidiness one: whether a
// notification preference EXISTS for a Team answers "is this person in it", and
// the guild page is public. The server decides — the preference list only contains
// Teams the caller may be notified about — and this file never infers membership
// from anything it can see on the page.
//
// **Muting is per-Team and covers all four streams.** The per-stream on/off lives
// on the account screen, where the catalog does; the thing that could not be
// expressed before phase 6 is "I am in five Teams and want notifications from
// one", and that is the only question this control asks.

export default function TeamNotifyToggle({ externalId, moduleId }) {
  const { user } = useAuth()
  const [state, setState] = useState({ loading: true, team: null, pref: null })
  const [busy, setBusy] = useState(false)

  const load = useCallback(async () => {
    // Anonymous viewers never fetch. The endpoint would 401 harmlessly, but a
    // guild page rendering a public roster should not put an authenticated
    // request on the wire for every visitor.
    if (!user) return setState({ loading: false, team: null, pref: null })
    try {
      const team = await api.teamByExternalId(moduleId, externalId)
      const { teams } = await api.teamNotificationPrefs()
      const pref = (teams || []).find((t) => t.teamId === team.id) || null
      setState({ loading: false, team, pref })
    } catch {
      // Same rule as the feed and the forum: this is core's content on a page
      // core does not own, so a failure renders nothing rather than putting an
      // error box on somebody else's surface.
      setState({ loading: false, team: null, pref: null })
    }
  }, [externalId, moduleId, user])

  useEffect(() => { load() }, [load])

  const { loading, pref } = state
  if (loading || !pref) return null

  async function toggle() {
    setBusy(true)
    // Optimistic, and reconciled from the server's echo rather than assumed: a
    // PUT that silently dropped the entry (a Team left in another tab) must not
    // leave the control claiming a state the server does not hold.
    const next = { ...pref, muted: !pref.muted }
    setState((s) => ({ ...s, pref: next }))
    try {
      const { teams } = await api.setTeamNotificationPrefs([
        { teamId: pref.teamId, muted: next.muted, emailMode: pref.emailMode },
      ])
      const echoed = (teams || []).find((t) => t.teamId === pref.teamId)
      if (echoed) setState((s) => ({ ...s, pref: echoed }))
    } catch {
      setState((s) => ({ ...s, pref }))
    } finally {
      setBusy(false)
    }
  }

  return (
    <div
      className="sans"
      style={{
        display: 'flex',
        alignItems: 'center',
        gap: 10,
        flexWrap: 'wrap',
        margin: '10px 0 0',
        fontSize: '0.84rem',
      }}
    >
      <button type="button" onClick={toggle} disabled={busy} className="btn btn-sq">
        {pref.muted ? 'Unmute notifications' : 'Mute notifications'}
      </button>
      <span className="dim">
        {pref.muted
          ? 'You get no notifications about this team.'
          : 'You get notifications about this team.'}
      </span>
      {/* The one link off this control, because "mute" is a blunt answer to a
          question the account screen asks properly — which streams, and whether
          email is on at all. */}
      <Link to="/account/notifications/settings" className="dim">All notification settings</Link>
    </div>
  )
}