'use client';

import { useCallback, useEffect, useState } from 'react';
import type { ContractState, PlaneState, StateSnapshot } from '@/lib/game/state';
import { PLANE_TYPES } from '@/lib/game/catalog';
import { formatCash, formatDeadlineRelative } from '@/lib/format';

interface RightPaneProps {
  state: StateSnapshot | null;
  loading: boolean;
  // Push the full snapshot returned by an action endpoint into the shared shell state (v0.10.0),
  // so the pane updates on click without waiting for the next poll tick.
  applySnapshot: (snapshot: StateSnapshot) => void;
}

const planeName = (p: PlaneState): string => PLANE_TYPES[p.model]?.name ?? p.model;

// Why a plane cannot be dispatched on `contract` — null when it can (grounded at the origin).
function dispatchReason(p: PlaneState, contract: ContractState): string | null {
  if (p.status !== 'available') return 'in flight';
  if (p.locationIcao !== contract.originIcao) return `at ${p.locationIcao}`;
  return null;
}

// Dispatch controls for one accepted, not-yet-dispatched contract: a plane picker where only
// grounded planes at the origin are enabled (others disabled with the reason), plus a dispatch
// button bound to the selection. The effective selection is the user's pick while it stays
// eligible, else auto-tracks the first eligible plane so a fresh contract needs one click.
function DispatchControls({
  contract,
  planes,
  busy,
  onDispatch,
}: {
  contract: ContractState;
  planes: PlaneState[];
  busy: boolean;
  onDispatch: (planeId: string) => void;
}) {
  const [selectedId, setSelectedId] = useState<string | null>(null);
  const effective =
    planes.find((p) => p.id === selectedId && dispatchReason(p, contract) === null) ??
    planes.find((p) => dispatchReason(p, contract) === null) ??
    null;

  return (
    <div className="dispatch-controls">
      <select
        data-testid={`dispatch-plane-${contract.id}`}
        aria-label={`Dispatch plane for ${contract.originName} to ${contract.destName}`}
        value={effective?.id ?? ''}
        onChange={(e) => setSelectedId(e.target.value || null)}
      >
        {planes.map((p) => {
          const reason = dispatchReason(p, contract);
          return (
            <option key={p.id} value={p.id} disabled={reason !== null}>
              {planeName(p)}
              {reason ? ` — ${reason}` : ''}
            </option>
          );
        })}
      </select>
      <button
        type="button"
        data-testid={`dispatch-${contract.id}`}
        className="pane-btn"
        disabled={busy || effective === null}
        onClick={() => {
          if (effective) onDispatch(effective.id);
        }}
      >
        Dispatch
      </button>
    </div>
  );
}

export default function RightPane({ state, loading, applySnapshot }: RightPaneProps) {
  const [busy, setBusy] = useState(false);
  // Inline error from a failed action — auto-clears on the next successful poll (the shell's
  // snapshot prop changes every tick) or the next successful action.
  const [actionError, setActionError] = useState<string | null>(null);
  useEffect(() => {
    if (state !== null) setActionError(null);
  }, [state]);

  // Market picker selections — same "effective selection" pattern as DispatchControls: the
  // user's pick while it stays valid, else a sensible default (first catalog entry / first plane).
  const [buyModelId, setBuyModelId] = useState<string | null>(null);
  const [sellPlaneId, setSellPlaneId] = useState<string | null>(null);
  const [refuelPlaneId, setRefuelPlaneId] = useState<string | null>(null);

  // POST an action endpoint. Every success returns the FULL post-action snapshot (v0.8.0
  // convention) — pushed into the shared state immediately; a 4xx {error} body becomes the
  // inline pane error and the stale UI stays until the next poll. Buttons are disabled while
  // a request is in flight, so at most one action runs at a time.
  const runAction = useCallback(
    async (path: string, body?: unknown) => {
      if (busy) return;
      setBusy(true);
      try {
        const res = await fetch(path, {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: body === undefined ? undefined : JSON.stringify(body),
          cache: 'no-store',
        });
        const data = (await res.json()) as StateSnapshot & { error?: string };
        if (!res.ok) throw new Error(data.error ?? `HTTP ${res.status}`);
        setActionError(null);
        applySnapshot(data);
      } catch (err) {
        setActionError(err instanceof Error ? err.message : String(err));
      } finally {
        setBusy(false);
      }
    },
    [applySnapshot, busy],
  );

  if (loading && !state) {
    return (
      <aside data-testid="right-pane" className="pane right-pane">
        <h2 className="pane-title">Jobs &amp; Market</h2>
        <p data-testid="right-loading" className="pane-muted">Loading…</p>
      </aside>
    );
  }
  if (!state) return null;

  const clockMs = state.simState.clockMs;
  const open = state.contracts.filter((c) => c.status === 'open');
  const accepted = state.contracts.filter((c) => c.status === 'accepted');

  const catalog = state.catalog;
  const buyEntry = catalog.find((e) => e.model === buyModelId) ?? catalog[0] ?? null;

  const grounded = state.planes.filter((p) => p.status === 'available');
  const sellPlane = state.planes.find((p) => p.id === sellPlaneId && p.status === 'available') ?? grounded[0] ?? null;
  const refuelable = grounded.filter((p) => p.fuel < p.maxFuel);
  const refuelPlane =
    state.planes.find((p) => p.id === refuelPlaneId && p.status === 'available' && p.fuel < p.maxFuel) ??
    refuelable[0] ??
    null;

  // Previews computed client-side from the snapshot's catalog + economy constants (v0.10.0).
  const sellEntry = sellPlane ? catalog.find((e) => e.model === sellPlane.model) : undefined;
  const sellPayout = sellEntry ? Math.round(sellEntry.price * state.sellFraction * 100) / 100 : null;
  const refuelCost = refuelPlane ? (refuelPlane.maxFuel - refuelPlane.fuel) * state.fuelPricePerL : null;

  return (
    <aside data-testid="right-pane" className="pane right-pane">
      <h2 className="pane-title">Jobs &amp; Market</h2>

      <section className="pane-section">
        <h3 className="pane-heading">Open contracts</h3>
        {open.length === 0 ? (
          <p className="pane-muted">No open contracts.</p>
        ) : (
          <ul data-testid="open-contracts" className="contract-list">
            {open.map((c) => (
              <li key={c.id} data-testid={`open-contract-${c.id}`} className="contract-row">
                <div className="contract-main">
                  <span className="contract-route">{c.originName} → {c.destName}</span>
                  <button
                    type="button"
                    data-testid={`accept-${c.id}`}
                    className="pane-btn"
                    disabled={busy}
                    onClick={() => void runAction(`/api/contracts/${c.id}/accept`)}
                  >
                    Accept
                  </button>
                </div>
                <div className="contract-sub">
                  <span data-testid={`open-contract-reward-${c.id}`}>{formatCash(c.reward)}</span>
                  <span>{c.cargoType} × {c.cargoCount}</span>
                  <span data-testid={`open-contract-deadline-${c.id}`}>
                    {formatDeadlineRelative(c.deadlineSimTime, clockMs)}
                  </span>
                </div>
              </li>
            ))}
          </ul>
        )}
      </section>

      <section className="pane-section">
        <h3 className="pane-heading">Accepted</h3>
        {accepted.length === 0 ? (
          <p className="pane-muted">Nothing accepted yet.</p>
        ) : (
          <ul data-testid="accepted-contracts" className="contract-list">
            {accepted.map((c) => (
              <li key={c.id} data-testid={`accepted-contract-${c.id}`} className="contract-row">
                <div className="contract-main">
                  <span className="contract-route">{c.originName} → {c.destName}</span>
                  {c.planeId ? (
                    <span data-testid={`contract-inflight-${c.id}`} className="plane-status status-flying">
                      in flight
                    </span>
                  ) : null}
                </div>
                <div className="contract-sub">
                  <span>{formatCash(c.reward)}</span>
                  <span>{c.cargoType} × {c.cargoCount}</span>
                  <span>{formatDeadlineRelative(c.deadlineSimTime, clockMs)}</span>
                </div>
                {!c.planeId && (
                  <DispatchControls
                    contract={c}
                    planes={state.planes}
                    busy={busy}
                    onDispatch={(planeId) => void runAction(`/api/planes/${planeId}/dispatch`, { contractId: c.id })}
                  />
                )}
              </li>
            ))}
          </ul>
        )}
      </section>

      <section className="pane-section">
        <h3 className="pane-heading">Market</h3>

        <div className="market-row">
          <select
            data-testid="market-buy-model"
            aria-label="Plane to buy"
            value={buyEntry?.model ?? ''}
            onChange={(e) => setBuyModelId(e.target.value || null)}
          >
            {catalog.map((e) => (
              <option key={e.model} value={e.model}>
                {e.label}
              </option>
            ))}
          </select>
          <span data-testid="market-buy-price" className="market-preview">
            {buyEntry ? formatCash(buyEntry.price) : ''}
          </span>
          <button
            type="button"
            data-testid="market-buy"
            className="pane-btn"
            disabled={busy || buyEntry === null}
            onClick={() => {
              if (buyEntry) void runAction('/api/market/buy-plane', { model: buyEntry.model });
            }}
          >
            Buy
          </button>
        </div>

        <div className="market-row">
          <select
            data-testid="market-sell-plane"
            aria-label="Plane to sell"
            value={sellPlane?.id ?? ''}
            onChange={(e) => setSellPlaneId(e.target.value || null)}
          >
            {grounded.map((p) => (
              <option key={p.id} value={p.id}>
                {planeName(p)} — {p.locationIcao}
              </option>
            ))}
          </select>
          <span data-testid="market-sell-payout" className="market-preview">
            {sellPayout !== null ? formatCash(sellPayout) : ''}
          </span>
          <button
            type="button"
            data-testid="market-sell"
            className="pane-btn"
            disabled={busy || sellPlane === null}
            onClick={() => {
              if (sellPlane) void runAction('/api/market/sell-plane', { planeId: sellPlane.id });
            }}
          >
            Sell
          </button>
        </div>

        <div className="market-row">
          {refuelable.length === 0 ? (
            <span data-testid="market-refuel-none" className="pane-muted">
              All tanks full.
            </span>
          ) : (
            <>
              <select
                data-testid="market-refuel-plane"
                aria-label="Plane to refuel"
                value={refuelPlane?.id ?? ''}
                onChange={(e) => setRefuelPlaneId(e.target.value || null)}
              >
                {refuelable.map((p) => (
                  <option key={p.id} value={p.id}>
                    {planeName(p)} — {Math.round(p.fuel)} / {p.maxFuel} L
                  </option>
                ))}
              </select>
              <span data-testid="market-refuel-cost" className="market-preview">
                {refuelCost !== null ? formatCash(refuelCost) : ''}
              </span>
            </>
          )}
          <button
            type="button"
            data-testid="market-refuel"
            className="pane-btn"
            disabled={busy || refuelPlane === null}
            onClick={() => {
              if (refuelPlane) void runAction(`/api/planes/${refuelPlane.id}/refuel`);
            }}
          >
            Refuel
          </button>
        </div>
      </section>

      {actionError && <p data-testid="right-error" className="pane-error">{actionError}</p>}
    </aside>
  );
}