import { useEffect, useMemo, useState } from 'react'
import type { Dispatch, SetStateAction } from 'react'
import { createPortal } from 'react-dom'
import type { BattleEvent, Card, ClientMessage, GameView, PendingBattleDecision } from '../types'
import { CardView } from './CardView'
import { DiceRoll, ROLL_MS } from './DiceRoll'

// How long a settled rock roll (and its damage) stays on screen before the
// battle advances to the next step.
const ROCK_PAUSE_MS = 1000

interface Props {
  view: GameView
  send: (msg: ClientMessage) => void
  // Step is owned by Table so the event log can stay in sync with the replay.
  step: number
  setStep: Dispatch<SetStateAction<number>>
}

interface UnitVis {
  card: Card
  foods: Card[]
  bonus: number
  damage: number
  dying: boolean
}

interface SideVis {
  stack: number
  pending: Card[] // foods revealed (or prepped) waiting for a pet
  unit: UnitVis | null
  setAside: Card[] // fainted pets kept beside the arena with a pending effect
  // Ids of cards (set-aside pets or spent food perks) released this step: kept
  // in their arrays for one beat so they can animate out, cleared next event.
  leaving: string[]
}

// Milliseconds each event type stays on screen during playback.
const EVENT_MS: Record<BattleEvent['type'], number> = {
  prep: 700,
  reveal: 800,
  summon: 1000,
  mill: 700,
  // Lead-in before the dice appear; the roll itself is timed by ROLL_MS +
  // ROCK_PAUSE_MS once it's on screen (see the auto-advance effect).
  rock: 500,
  clash: 1400,
  shield: 900,
  strip: 1100,
  steal: 1100,
  eat: 1000,
  heal: 900,
  setaside: 700,
  release: 500,
  trumpet: 800,
  prevent: 900,
}

const appleCount = (foods: Card[]) => foods.filter((f) => f.food === 'apple').length

// replay applies the first `upto` events to fresh stacks and returns each
// seat's visual state. Units that died in the last applied event are still
// present with dying=true so they can animate out.
function replay(events: BattleEvent[], stackSizes: number[], upto: number): SideVis[] {
  const sides: SideVis[] = stackSizes.map((n) => ({
    stack: n,
    pending: [],
    unit: null,
    setAside: [],
    leaving: [],
  }))
  for (let k = 0; k < upto && k < events.length; k++) {
    for (const s of sides) {
      if (s.unit?.dying) s.unit = null // clear last step's casualties
      if (s.leaving.length) {
        // Drop cards that finished animating out last step.
        const gone = new Set(s.leaving)
        s.setAside = s.setAside.filter((c) => !gone.has(c.id))
        if (s.unit) s.unit.foods = s.unit.foods.filter((c) => !gone.has(c.id))
        s.pending = s.pending.filter((c) => !gone.has(c.id))
        s.leaving = []
      }
    }
    const ev = events[k]
    switch (ev.type) {
      case 'prep':
        sides[ev.seat!].pending.push(ev.card!)
        break
      case 'reveal': {
        const s = sides[ev.seat!]
        // The Golden Retriever is summoned straight into play, not flipped off
        // the deck, so it doesn't decrement the stack.
        if (ev.card?.name === 'Golden Retriever') {
          const trumpets = ev.count ?? 0
          s.unit = {
            card: ev.card!,
            // Show the Trumpets that powered it, fanned like food tokens.
            foods: Array.from({ length: trumpets }, (_, i) => ({
              id: `${ev.card!.id}-t${i}`,
              kind: 'food' as const,
              name: 'Trumpet',
              food: 'trumpet',
            })),
            bonus: 0,
            damage: 0,
            dying: false,
          }
          break
        }
        s.stack--
        const card = ev.card!
        if (card.kind === 'food') {
          s.pending.push(card)
        } else {
          s.unit = {
            card,
            foods: s.pending,
            bonus: ev.bonus ?? appleCount(s.pending),
            damage: 0,
            dying: false,
          }
          s.pending = []
        }
        break
      }
      case 'summon':
        sides[ev.seat!].stack++
        break
      case 'mill':
        sides[ev.seat!].stack--
        break
      case 'rock': {
        const u = sides[ev.target!].unit
        if (u) {
          u.damage = ev.damageAfter ?? u.damage
          if (ev.targetDied) u.dying = true
        }
        break
      }
      case 'clash':
        sides.forEach((s, seat) => {
          if (!s.unit) return
          s.unit.damage = ev.damage?.[seat] ?? s.unit.damage
          if (ev.died?.[seat]) s.unit.dying = true
        })
        break
      case 'strip': {
        const u = sides[ev.target!].unit
        if (u) {
          u.bonus -= appleCount(u.foods)
          u.foods = []
          if (ev.targetDied) u.dying = true
        }
        break
      }
      case 'steal': {
        const from = sides[ev.target!].unit
        const to = sides[ev.seat!].unit
        const n = ev.count ?? 0
        if (from && to) {
          let moved = 0
          from.foods = from.foods.filter((f) => {
            if (f.food === 'apple' && moved < n) {
              moved++
              to.foods.push(f)
              return false
            }
            return true
          })
          from.bonus -= moved
          to.bonus += moved
          if (ev.targetDied) from.dying = true
        }
        break
      }
      case 'eat': {
        const u = sides[ev.seat!].unit
        if (u) u.bonus = ev.bonus ?? u.bonus
        break
      }
      case 'heal': {
        const u = sides[ev.seat!].unit
        if (u) u.damage = ev.damageAfter ?? u.damage
        break
      }
      case 'shield':
        break // pure animation; no state change
      case 'trumpet':
        break // pure animation; the pool isn't drawn on the board
      case 'prevent': {
        // Cone Snail shaved damage off the hit; the reduced total rides along.
        const u = sides[ev.seat!].unit
        if (u) u.damage = ev.damageAfter ?? u.damage
        break
      }
      case 'setaside':
        if (ev.card) sides[ev.seat!].setAside.push(ev.card)
        break
      case 'release': {
        // A spent card leaves the play area: a set-aside pet (Turtle) or a
        // used-up food perk (Melon), which lives in the pet's food fan. Flag it
        // rather than removing it, so it animates out before unmounting.
        const id = ev.card?.id
        if (id) sides[ev.seat!].leaving.push(id)
        break
      }
    }
  }
  return sides
}

// unitPop decides the floating effect text over a seat's pet for the event
// currently playing. Null = nothing.
function unitPop(ev: BattleEvent | null, seat: number, events: BattleEvent[], step: number): string | null {
  if (!ev) return null
  switch (ev.type) {
    case 'rock':
      if (ev.target !== seat) return null
      return ev.roll === 0 ? 'miss!' : `−${ev.roll}`
    case 'clash': {
      const taken = clashDamageTaken(events, step - 1, seat)
      return taken > 0 ? `−${taken}` : null
    }
    case 'shield':
      return ev.seat === seat ? '🛡️' : null
    case 'prevent':
      return ev.seat === seat ? `🛡️ −${ev.count}` : null
    case 'trumpet':
      if (ev.seat !== seat) return null
      return (ev.count ?? 0) >= 0 ? `🎺 +${ev.count}` : `🎺 ${ev.count}`
    case 'eat':
      return ev.seat === seat ? '🍎' : null
    case 'heal':
      return ev.seat === seat ? '💚 +1' : null
    case 'strip':
      return ev.target === seat ? '💨' : null
    case 'steal':
      if (ev.seat === seat) return `+🍎×${ev.count}`
      if (ev.target === seat) return `−🍎×${ev.count}`
      return null
    default:
      return null
  }
}

// BattlePhase plays back the battle log: cards flip off each deck, rocks
// fly, pets clash, the fallen fade out, then the round result lands.
export function BattlePhase({ view, send, step, setStep }: Props) {
  const battle = view.battle!
  const events = battle.events ?? []
  const [acked, setAcked] = useState(false)
  // The deck-peek popover lives inside .battlefield, which sets overflow-x
  // (and thus overflow-y) to auto — so an absolutely-positioned popover gets
  // clipped to the battlefield. We anchor it to the hovered stack's viewport
  // rect and portal it to <body> so it floats over the whole window instead.
  const [peek, setPeek] = useState<{ seat: number; dir: 'left' | 'right'; rect: DOMRect } | null>(
    null,
  )
  const lineups = battle.lineups
  const done = step >= events.length
  const lastEvent = step > 0 ? events[step - 1] : null

  // paused freezes auto-advance so the player can walk the log manually.
  const [paused, setPaused] = useState(false)

  // A rock event on screen scrambles its dice first; only once they settle do
  // we apply the damage and reveal the result.
  const showingRock = !done && lastEvent?.type === 'rock'
  const [rockSettled, setRockSettled] = useState(false)
  useEffect(() => {
    if (!showingRock) {
      setRockSettled(true)
      return
    }
    setRockSettled(false)
    const t = window.setTimeout(() => setRockSettled(true), ROLL_MS)
    return () => window.clearTimeout(t)
  }, [step, showingRock])

  useEffect(() => {
    if (done || paused) return
    // The rock roll owns its timing: hold until the dice settle, then a full
    // beat with the damage showing before moving on.
    const delay = showingRock ? ROLL_MS + ROCK_PAUSE_MS : (EVENT_MS[events[step].type] ?? 1000)
    const t = window.setTimeout(() => setStep((s) => s + 1), delay)
    return () => window.clearTimeout(t)
  }, [step, done, paused, events, showingRock])

  // Manual controls. Stepping by hand pauses playback so it doesn't fight you.
  const stepTo = (n: number) => {
    setPaused(true)
    setStep(Math.max(0, Math.min(events.length, n)))
  }
  const restart = () => {
    setPaused(false)
    setStep(0)
  }

  // While the dice are still scrambling, replay only up to just before the
  // rock so its damage/faint hasn't landed yet.
  const upto = showingRock && !rockSettled ? step - 1 : step
  const sides = useMemo(
    () => replay(events, battle.stackSizes, upto),
    [events, battle.stackSizes, upto],
  )

  const youSeat = view.youSeat
  const oppSeat = view.players.find((p) => p.seat !== youSeat)?.seat ?? 1
  const you = view.players[youSeat]
  const opp = view.players[oppSeat]
  const won = battle.winnerSeat === youSeat
  const draw = battle.winnerSeat < 0

  // Dice for the rock event currently on screen. renderSide draws them under
  // the throwing side's deck; `step` keys the tray so the scramble replays for
  // every rock event.
  const rockDice =
    !done && lastEvent?.type === 'rock' && lastEvent.dice && lastEvent.dice.length > 0
      ? lastEvent.dice
      : null

  function renderSide(seat: number, dir: 'left' | 'right') {
    const s = sides[seat]
    const clashing = !done && lastEvent?.type === 'clash' && s.unit && !s.unit.dying
    const clashDying = lastEvent?.type === 'clash' && s.unit?.dying
    const rockVictim = lastEvent?.type === 'rock' && lastEvent.target === seat
    const summoning = !done && lastEvent?.type === 'summon' && lastEvent.seat === seat
    const milling = !done && lastEvent?.type === 'mill' && lastEvent.seat === seat
    const revealing = !done && lastEvent?.type === 'reveal' && lastEvent.seat === seat
    // A food (apple) that just landed on this side's fan — reveal off the deck or
    // a Battle Prep hand-out — animates in from the deck rather than popping.
    const newFoodId =
      !done &&
      lastEvent?.seat === seat &&
      (lastEvent.type === 'prep' ||
        (lastEvent.type === 'reveal' && lastEvent.card?.kind === 'food'))
        ? lastEvent.card?.id
        : null
    // A pet just set aside rises up from the arena into the set-aside row.
    const newSetAsideId =
      !done && lastEvent?.type === 'setaside' && lastEvent.seat === seat
        ? lastEvent.card?.id
        : null
    // Hold the −N / miss! pop until the dice settle.
    const pop = done || (showingRock && !rockSettled) ? null : unitPop(lastEvent, seat, events, step)

    const lineup = lineups?.[seat] ?? []
    const stackEl = (
      <div
        className={`stackpile ${lineup.length ? 'peekable' : ''}`}
        onMouseEnter={
          lineup.length
            ? (e) => setPeek({ seat, dir, rect: e.currentTarget.getBoundingClientRect() })
            : undefined
        }
        onMouseLeave={() => setPeek((p) => (p?.seat === seat ? null : p))}
        title={lineup.length ? 'Hover to see the whole deck' : undefined}
      >
        {s.stack > 0 ? (
          <div className="card-back">
            <span className="card-back-count">{s.stack}</span>
          </div>
        ) : (
          <div className="card-slot-empty stack-empty" />
        )}
        {summoning && lastEvent?.card && (
          // Fly the spawned apple/bee out from where the pet stood (the unit
          // zone sits on the inner edge) onto the top of the deck, so it reads
          // as coming from the pet that just fainted.
          <div className={`summon-pop ${dir === 'left' ? 'summon-from-right' : 'summon-from-left'}`}>
            <CardView card={lastEvent.card} size="sm" />
          </div>
        )}
        {milling && lastEvent?.card && (
          <div className="summon-pop mill-pop">
            <CardView card={lastEvent.card} size="sm" dead />
          </div>
        )}
        {rockDice && lastEvent?.seat === seat && (
          // The dice roll sits directly under the throwing side's deck.
          <div className="stack-dice">
            <DiceRoll key={step} dice={rockDice} side={dir} />
          </div>
        )}
      </div>
    )

    // Set-aside pets (Blowfish, Badger, …) sit in a row above the active pet
    // until their pending effect resolves.
    const setAsideEl = s.setAside.length > 0 && (
      <div className="setaside-row">
        {s.setAside.map((c) => (
          <div
            key={c.id}
            className={`setaside-card ${s.leaving.includes(c.id) ? 'is-leaving' : ''} ${
              c.id === newSetAsideId ? 'setaside-in' : ''
            }`}
          >
            <CardView card={c} size="sm" />
          </div>
        ))}
      </div>
    )

    // Foods attached to the pet (or, before one is in play, waiting for the
    // next) fan out below it: a vertical stack overlapping ~¾, so only each
    // card's top edge shows — like cards laid out on a table.
    const foods = s.unit ? s.unit.foods : s.pending
    const foodFanEl = foods.length > 0 && (
      <div className="food-fan">
        {foods.map((f, i) => (
          <div
            key={f.id}
            className={`food-fan-card ${s.leaving.includes(f.id) ? 'is-leaving' : ''} ${
              f.id === newFoodId ? `food-in food-in-${dir}` : ''
            }`}
            style={{ zIndex: i + 1 }}
          >
            <CardView card={f} size="sm" />
          </div>
        ))}
      </div>
    )

    const unitEl = (
      <div className="battle-unit-zone">
        {setAsideEl}
        {foodFanEl}
        {s.unit && (
          <div
            key={`${s.unit.card.id}-${clashing || rockVictim ? step : 'idle'}`}
            className={[
              'battle-unit',
              clashing || clashDying ? `clash-${dir}` : '',
              s.unit.dying ? 'unit-dying' : '',
              revealing ? `unit-reveal unit-reveal-${dir}` : '',
            ]
              .filter(Boolean)
              .join(' ')}
          >
            <CardView
              card={s.unit.card}
              bonus={s.unit.bonus}
              damage={s.unit.damage}
              dead={s.unit.dying}
            />
            {pop && (
              <div key={`pop-${step}`} className={pop.startsWith('−') ? 'damage-pop' : 'fx-pop'}>
                {pop}
              </div>
            )}
          </div>
        )}
      </div>
    )

    return dir === 'left' ? (
      <div className="battle-side">
        {stackEl}
        {unitEl}
      </div>
    ) : (
      <div className="battle-side">
        {unitEl}
        {stackEl}
      </div>
    )
  }

  return (
    <div className="battle">
      <div className="battle-header">
        <h2>Battle! Round {battle.round}</h2>
        <div className="battle-controls">
          <button className="btn btn-ghost btn-sm" onClick={restart} title="Replay from the start">
            ⏮
          </button>
          <button
            className="btn btn-ghost btn-sm"
            onClick={() => stepTo(step - 1)}
            disabled={step === 0}
            title="Previous step"
          >
            |◀
          </button>
          <button
            className="btn btn-ghost btn-sm"
            onClick={() => setPaused((p) => !p)}
            disabled={done}
            title={paused ? 'Play' : 'Pause'}
          >
            {paused || done ? '▶' : '⏸'}
          </button>
          <button
            className="btn btn-ghost btn-sm"
            onClick={() => stepTo(step + 1)}
            disabled={done}
            title="Next step"
          >
            ▶|
          </button>
          <span className="battle-step">
            {Math.min(step, events.length)} / {events.length}
          </span>
          <button
            className="btn btn-ghost btn-sm"
            onClick={() => setStep(events.length)}
            disabled={done}
            title="Skip to the end"
          >
            Skip ⏭
          </button>
        </div>
      </div>

      <div className="battle-names">
        <span>{you?.name} (you)</span>
        <span className="battle-vs">VS</span>
        <span>{opp?.name}</span>
      </div>

      <div className="battlefield">
        {renderSide(youSeat, 'left')}
        <div className="battle-center" aria-hidden>
          <span className="battle-center-bolt">⚡</span>
        </div>
        {renderSide(oppSeat, 'right')}
      </div>

      {peek &&
        (() => {
          const lineup = lineups?.[peek.seat] ?? []
          if (!lineup.length) return null
          const style: React.CSSProperties = {
            bottom: window.innerHeight - peek.rect.top + 8,
            ...(peek.dir === 'left'
              ? { left: peek.rect.left }
              : { right: window.innerWidth - peek.rect.right }),
          }
          return createPortal(
            <div className={`deck-peek deck-peek-${peek.dir}`} style={style}>
              <div className="deck-peek-label">
                {peek.seat === youSeat ? 'Your' : 'Opponent’s'} deck · {lineup.length} card
                {lineup.length !== 1 ? 's' : ''} (top first)
              </div>
              <div className="deck-peek-cards">
                {lineup.map((c, i) => (
                  <CardView key={c.id || i} card={c} size="sm" />
                ))}
              </div>
            </div>,
            document.body,
          )
        })()}

      {done && view.pendingBattle ? (
        <BattleDecision
          pd={view.pendingBattle}
          youSeat={youSeat}
          oppName={opp?.name ?? 'Opponent'}
          send={send}
        />
      ) : (
        done && (
          <div className={`battle-result ${draw ? 'is-draw' : won ? 'is-win' : 'is-loss'}`}>
            <div className="battle-result-title">
              {draw ? 'Draw!' : won ? 'Victory!' : 'Defeat…'}
            </div>
            {!draw && (
              <div className="battle-result-sub">
                {view.players[battle.winnerSeat]?.name} wins{' '}
                {'🏆'.repeat(battle.trophies)}
              </div>
            )}
            {draw && <div className="battle-result-sub">No trophies awarded</div>}
            {acked ? (
              <p className="muted">Waiting for opponent…</p>
            ) : (
              <button
                className="btn btn-primary btn-big"
                onClick={() => {
                  setAcked(true)
                  send({ type: 'ready' })
                }}
              >
                {battle.round >= view.maxRounds ? 'See final results' : 'Next round →'}
              </button>
            )}
          </div>
        )
      )}
    </div>
  )
}

// BattleDecision is the mid-battle prompt (Golden pack: Nurse Shark). The
// deciding player picks how many Trumpets to spend; the other player waits.
function BattleDecision({
  pd,
  youSeat,
  oppName,
  send,
}: {
  pd: PendingBattleDecision
  youSeat: number
  oppName: string
  send: (msg: ClientMessage) => void
}) {
  const [sent, setSent] = useState(false)
  // Reset when a fresh decision arrives (e.g. a second Nurse Shark).
  useEffect(() => setSent(false), [pd.seat, pd.trumpets, pd.max])
  if (pd.seat !== youSeat) {
    return (
      <div className="battle-result">
        <p className="muted">{oppName} is deciding {pd.petName}…</p>
      </div>
    )
  }
  return (
    <div className="battle-result battle-decision">
      <div className="battle-result-title">{pd.petName}</div>
      <div className="battle-result-sub">
        Spend Trumpets to throw 2 🪨 each — you hold {pd.trumpets} 🎺
      </div>
      <div className="battle-decision-options">
        {Array.from({ length: pd.max + 1 }, (_, n) => (
          <button
            key={n}
            className="btn btn-primary"
            disabled={sent}
            onClick={() => {
              setSent(true)
              send({ type: 'battleChoose', value: n })
            }}
          >
            {n === 0 ? 'Spend none' : `${n} 🎺 → ${2 * n} 🪨`}
          </button>
        ))}
      </div>
    </div>
  )
}

// clashDamageTaken computes how much damage a seat's pet took in the clash
// at event index `idx` (its damage total there minus its total beforehand).
function clashDamageTaken(events: BattleEvent[], idx: number, seat: number): number {
  const ev = events[idx]
  if (ev?.type !== 'clash') return 0
  const after = ev.damage?.[seat] ?? 0
  // Walk back to the pet's damage before this clash.
  let before = 0
  for (let k = idx - 1; k >= 0; k--) {
    const e = events[k]
    if (e.type === 'reveal' && e.seat === seat && e.card?.kind === 'pet') break
    if ((e.type === 'rock' || e.type === 'heal') && (e.target ?? e.seat) === seat) {
      before = e.damageAfter ?? 0
      break
    }
    if (e.type === 'clash') {
      before = e.damage?.[seat] ?? 0
      break
    }
  }
  return after - before
}