// ── The live map ──────────────────────────────────────────────────────────
//
// R9's page, as PLAN.md §30.2 drew it: the picture of the current map under
// four layers, each with its own switch, polled every ten seconds while the tab
// is visible (D14) and not at all while it is hidden.
//
// **Nothing here decides who may see what.** The server sends only the layers
// this viewer may see — a hidden one is absent from the answer, not present and
// hidden — so the checkboxes below are a reader's convenience and never a
// boundary. A layer the viewer cannot see is still LISTED, disabled, with who
// can: "staff only" explains an empty map where silence would imply an empty
// server (§23.3's shape).
//
// Leaflet arrives in a chunk of its own when this tab first mounts (D120, see
// `lib/leaflet.js`). The page draws with circle and div markers only, so
// Leaflet's image assets are never needed.

import { useEffect, useMemo, useRef, useState } from 'react'
import { ErrorState, Loading, useAsync } from '../core.js'
import Empty from './Empty.jsx'
import usePolled from '../hooks/usePolled.js'
import { ago } from '../lib/format.js'
import { boundsOf, countdown, grid, gridLabel, toLatLng } from '../lib/mapGeometry.js'
import api, { BASE } from '../api.js'

const STYLE_ID = 'rust-leaflet-css'

/** The narrowest a grid cell may be on screen, in pixels, and still carry its label. */
const LABEL_MIN_CELL_PX = 30

/** The layers, in the order the legend lists them, with their marker colours. */
const LAYERS = [
  { id: 'world', label: 'Monuments & world events' },
  { id: 'events', label: 'Site events' },
  { id: 'players', label: 'Players' },
  { id: 'bases', label: 'Bases' },
]

const COLOURS = {
  monument: '#e8d9a8',
  cargo: '#4fc3f7',
  heli: '#ef5350',
  chinook: '#ffa726',
  bradley: '#a1887f',
  supply: '#66bb6a',
  crate: '#ffee58',
  event: '#ce93d8',
  online: '#ffffff',
  sleeping: '#9e9e9e',
  tc: '#ff7043',
  vending: '#26a69a',
  self: '#00e5ff',
  mate: '#7cffb2',
}

const WORLD_NAMES = {
  cargo: 'Cargo ship',
  heli: 'Patrol helicopter',
  chinook: 'Chinook',
  bradley: 'Bradley APC',
  supply: 'Supply drop',
  crate: 'Locked crate',
}

const AUDIENCE_WORDS = { public: 'everyone', signed_in: 'signed-in players', staff: 'staff only' }

export default function MapView({ serverId, online }) {
  const { data: meta, loading, error } = useAsync(() => api.servers.map(serverId), [serverId])
  const geometry = meta ? meta.geometry : null

  const [leaflet, setLeaflet] = useState(null)
  const [leafletError, setLeafletError] = useState(null)
  const [shown, setShown] = useState({ grid: true, world: true, events: true, players: true, bases: true, mates: true })

  useEffect(() => {
    let alive = true
    import('../lib/leaflet.js')
      .then((mod) => {
        if (!alive) return
        if (typeof document !== 'undefined' && !document.getElementById(STYLE_ID)) {
          const style = document.createElement('style')
          style.id = STYLE_ID
          style.textContent = mod.css
          document.head.appendChild(style)
        }
        setLeaflet(mod)
      })
      .catch((err) => alive && setLeafletError(err))
    return () => {
      alive = false
    }
  }, [])

  const anyLive = Boolean(meta && (LAYERS.some((l) => meta.layers[l.id].visible) || meta.mates.visible))
  const live = usePolled(() => api.servers.mapLive(serverId), {
    key: serverId,
    intervalMs: (meta && meta.pollMs) || 10_000,
    enabled: Boolean(geometry) && anyLive,
  })

  const container = useRef(null)
  const mapRef = useRef(null)
  const groups = useRef(null)

  // The map itself: made once per server and geometry, torn down with them.
  useEffect(() => {
    if (!leaflet || !geometry || !container.current) return undefined
    const { L } = leaflet
    const bounds = boundsOf(geometry)
    const map = L.map(container.current, {
      crs: L.CRS.Simple,
      minZoom: -4,
      maxZoom: 2,
      zoomSnap: 0.25,
      attributionControl: false,
      // Some things sail off the edge: the rig's cargo ship spent the probe
      // outside the picture entirely. The view may follow them a little way.
      maxBounds: L.latLngBounds(bounds).pad(0.5),
    })
    if (meta.picture) L.imageOverlay(`${BASE}${meta.picture.path}`, bounds).addTo(map)
    map.fitBounds(bounds)

    const made = {}
    for (const id of ['grid', 'monuments', 'world', 'events', 'players', 'bases', 'mates']) made[id] = L.layerGroup().addTo(map)
    // The labels are a layer of their own inside the grid's, shown only when a cell
    // is wide enough on screen to hold one: at the fitted zoom a 20-cell map's
    // labels overlap into a wall of text (found on the phase 14 walk).
    const labels = L.layerGroup()
    const cellPx = () => geometry.gridCellSize * ((geometry.width - 2 * geometry.oceanMargin) / geometry.worldSize) * 2 ** map.getZoom()
    const fitLabels = () => {
      const want = cellPx() >= LABEL_MIN_CELL_PX
      if (want && !made.grid.hasLayer(labels)) made.grid.addLayer(labels)
      if (!want && made.grid.hasLayer(labels)) made.grid.removeLayer(labels)
    }
    map.on('zoomend', fitLabels)

    const g = grid(geometry)
    for (const [[x1, z1], [x2, z2]] of g.lines) {
      L.polyline([toLatLng(geometry, x1, z1), toLatLng(geometry, x2, z2)], {
        color: '#ffffff',
        weight: 1,
        opacity: 0.18,
        interactive: false,
      }).addTo(made.grid)
    }
    for (const label of g.labels) {
      L.marker(toLatLng(geometry, label.x, label.z), {
        interactive: false,
        keyboard: false,
        icon: L.divIcon({
          className: '',
          html: `<span style="font:600 10px/1 system-ui,sans-serif;color:rgba(255,255,255,.55);padding:2px 3px;display:block;white-space:nowrap">${label.text}</span>`,
          iconSize: null,
          iconAnchor: [0, 0],
        }),
      }).addTo(labels)
    }
    fitLabels()

    for (const m of meta.monuments || []) {
      L.circleMarker(toLatLng(geometry, m.x, m.z), {
        radius: 4,
        color: '#000',
        weight: 1,
        fillColor: COLOURS.monument,
        fillOpacity: 0.9,
      })
        .bindTooltip(`${escape(m.label)} · ${escape(m.grid || gridLabel(geometry, m.x, m.z) || '')}`)
        .addTo(made.monuments)
    }

    mapRef.current = map
    groups.current = made
    return () => {
      map.remove()
      mapRef.current = null
      groups.current = null
    }
    // `meta` is replaced only when the server changes, with the geometry.
  }, [leaflet, geometry]) // eslint-disable-line react-hooks/exhaustive-deps

  // What moves: every group cleared and redrawn from the latest answer. The
  // counts are small — a busy server is a few hundred markers — and a redraw is
  // simpler to get right than a diff.
  useEffect(() => {
    const made = groups.current
    if (!leaflet || !made || !geometry) return
    const { L } = leaflet
    const answer = live.data || {}
    const at = (p) => toLatLng(geometry, p.x, p.z)
    for (const id of ['world', 'events', 'players', 'bases', 'mates']) made[id].clearLayers()

    for (const w of answer.world || []) {
      let tip = WORLD_NAMES[w.kind] || w.kind
      if (w.kind === 'crate' && w.hackLeftSec != null) tip += ` — ${countdown(w.hackLeftSec)} left on the hack`
      if (w.kind === 'crate' && w.hacked) tip += ' — hacked'
      dot(L, at(w), COLOURS[w.kind] || COLOURS.crate, w.kind === 'cargo' ? 7 : 5).bindTooltip(escape(tip)).addTo(made.world)
    }

    const px = (metres) => metres * ((geometry.width - 2 * geometry.oceanMargin) / geometry.worldSize)
    for (const e of answer.events || []) {
      if (e.kind === 'zone') {
        L.circle(at(e), { radius: px(Number(e.radius) || 0), color: COLOURS.event, weight: 2, fillOpacity: 0.12 })
          .bindTooltip(escape(e.name ? `Event zone · ${e.name}` : 'Event zone'))
          .addTo(made.events)
      } else {
        dot(L, at(e), COLOURS.event, 5).bindTooltip(e.kind === 'npc' ? 'Event NPC' : 'Event crate').addTo(made.events)
      }
    }

    for (const p of answer.players || []) {
      dot(L, at(p), p.online ? COLOURS.online : COLOURS.sleeping, p.online ? 5 : 4)
        .bindTooltip(escape(`${p.name || p.steamId}${p.online ? (p.sleeping ? ' · sleeping' : '') : ' · asleep, offline'}`))
        .addTo(made.players)
    }

    for (const b of answer.bases || []) {
      dot(L, at(b), COLOURS[b.kind] || COLOURS.tc, 4).bindTooltip(b.kind === 'tc' ? 'Tool cupboard' : 'Vending machine').addTo(made.bases)
    }

    for (const m of answer.mates || []) {
      dot(L, at(m), m.self ? COLOURS.self : COLOURS.mate, m.self ? 8 : 6, 2)
        .bindTooltip(escape(m.self ? `You${m.online ? '' : ' (asleep, offline)'}` : m.name || 'Clan mate'))
        .addTo(made.mates)
    }
  }, [leaflet, geometry, live.data])

  // The legend's checkboxes: a group is on the map or off it.
  useEffect(() => {
    const map = mapRef.current
    const made = groups.current
    if (!map || !made) return
    const want = { grid: shown.grid, monuments: shown.world, world: shown.world, events: shown.events, players: shown.players, bases: shown.bases, mates: shown.mates }
    for (const [id, on] of Object.entries(want)) {
      if (on && !map.hasLayer(made[id])) made[id].addTo(map)
      if (!on && map.hasLayer(made[id])) map.removeLayer(made[id])
    }
  }, [shown, leaflet, geometry])

  const status = useMemo(() => liveStatus(live, anyLive, online), [live, anyLive, online])

  if (loading) return <Loading />
  if (error) return <ErrorState error={error} />
  if (!geometry) {
    return (
      <Empty
        title="No map yet"
        message="This server has not described its map to the site yet. It will appear once the server is up and has said which map it is on."
      />
    )
  }
  if (leafletError) return <ErrorState error={leafletError} />

  return (
    <div className="sans">
      {!meta.picture && (
        <p style={{ color: 'var(--dim)', fontSize: '0.8rem', marginTop: 0 }}>
          This server has no picture of its map, so the layers are drawn on a plain background.
        </p>
      )}
      <div style={{ position: 'relative', zIndex: 0 }}>
        <div
          ref={container}
          role="application"
          aria-label="Map of the server"
          style={{
            height: 'min(70vh, 760px)',
            minHeight: 320,
            borderRadius: 8,
            border: '1px solid var(--line)',
            background: geometry.background || '#0b3b4a',
          }}
        />
        {!leaflet && (
          <div style={{ position: 'absolute', inset: 0, display: 'grid', placeItems: 'center' }}>
            <Loading />
          </div>
        )}
      </div>

      <p style={{ color: 'var(--dim)', fontSize: '0.78rem', margin: '8px 0 16px' }}>{status}</p>

      <Legend meta={meta} live={live.data} shown={shown} onToggle={(id) => setShown((s) => ({ ...s, [id]: !s[id] }))} />
    </div>
  )
}

function Legend({ meta, live, shown, onToggle }) {
  const row = (id, label, swatches, visible, note) => (
    <li key={id} style={{ display: 'flex', alignItems: 'baseline', gap: 10, padding: '6px 0', borderBottom: '1px solid var(--line-soft, var(--line))' }}>
      <label style={{ display: 'flex', alignItems: 'center', gap: 8, cursor: visible ? 'pointer' : 'default', color: visible ? 'var(--ink)' : 'var(--dim)' }}>
        <input type="checkbox" checked={visible && shown[id]} disabled={!visible} onChange={() => onToggle(id)} />
        {label}
      </label>
      <span style={{ display: 'inline-flex', gap: 4 }}>
        {swatches.map((c) => (
          <span key={c} aria-hidden="true" style={{ width: 10, height: 10, borderRadius: '50%', background: c, display: 'inline-block', border: '1px solid rgba(0,0,0,.4)' }} />
        ))}
      </span>
      {note && <span style={{ color: 'var(--dim)', fontSize: '0.76rem', marginLeft: 'auto', textAlign: 'right' }}>{note}</span>}
    </li>
  )

  const hiddenNote = (layer) => {
    const words = AUDIENCE_WORDS[layer.audience] || AUDIENCE_WORDS.staff
    if (layer.audience === 'signed_in') return 'Sign in to see this layer.'
    return `Shown to ${words}.`
  }

  const swatches = {
    world: [COLOURS.monument, COLOURS.cargo, COLOURS.heli, COLOURS.crate],
    events: [COLOURS.event],
    players: [COLOURS.online, COLOURS.sleeping],
    bases: [COLOURS.tc, COLOURS.vending],
  }

  return (
    <ul style={{ listStyle: 'none', margin: 0, padding: 0, fontSize: '0.86rem' }}>
      {row('grid', 'Grid', [], true, null)}
      {LAYERS.map((l) => {
        const layer = meta.layers[l.id]
        let note = layer.visible ? null : hiddenNote(layer)
        if (l.id === 'players' && layer.cappedByPresence && !layer.visible) {
          note = `${note} Limited by who may see who is online.`
        }
        if (layer.visible && l.id === 'players' && live && live.playersTruncated) note = 'Not every sleeper is shown.'
        if (layer.visible && l.id === 'bases' && live && live.basesTruncated) note = 'Not every base is shown.'
        return row(l.id, l.label, swatches[l.id], layer.visible, note)
      })}
      {meta.mates.visible &&
        row('mates', 'You and your clan', [COLOURS.self, COLOURS.mate], true, 'Your own position, and clan mates who are online.')}
      {!meta.mates.visible && meta.mates.on && meta.mates.signedIn && !meta.mates.linked &&
        row('mates', 'You and your clan', [COLOURS.self, COLOURS.mate], false, 'Link your Steam account to see yourself and your clan here.')}
    </ul>
  )
}

function dot(L, latlng, colour, radius, weight = 1) {
  return L.circleMarker(latlng, { radius, color: '#000', weight, fillColor: colour, fillOpacity: 0.95 })
}

/** Tooltips are HTML in Leaflet, and a player's name is text they typed. */
function escape(text) {
  return String(text).replace(/[&<>"']/g, (c) => ({ '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' })[c])
}

function liveStatus(live, anyLive, online) {
  if (!anyLive) return 'No moving layers are shown to you on this server.'
  if (live.loading) return 'Asking the server where things are…'
  const data = live.data
  if (data && data.live === false) {
    return online
      ? 'The server did not say where things are just now; it is asked again every ten seconds.'
      : 'The server is offline, so nothing is moving on its map.'
  }
  if (live.error && !data) return 'Positions could not be loaded.'
  return live.at ? `Positions as of ${ago(new Date(live.at).toISOString())}, refreshed every ten seconds while this tab is open.` : ''
}