/**
 * The Variables tab (#252): every variable of a behavior, a Variables asset or a placed behavior,
 * with the very rows the inspector draws for them – or one list, as deep inside them as it sits.
 * One editor for every such tab, pointed at the target of the one showing, like the asset editors.
 */
import type { Container } from 'pixi.js';
import { isVariableOwner } from '../../core/model/Asset';
import { findObject } from '../../core/model/hierarchy';
import { findAsset } from '../../core/model/Project';
import { objectName } from '../../core/model/SceneObject';
import { Label, ScrollContainer, Theme, ui, VStack, HStack } from '../../ui';
import { assetSignature, buildVariables, refreshAssetSection } from '../inspector/assetSection';
import type { InspectorHost } from '../inspector/host';
import { viewOf } from '../inspector/objectQueries';
import {
  buildOwnRows,
  objectSignature,
  pickableObjects,
  refreshObjectSection,
} from '../inspector/objectSection';
import { InlineList, ListHead } from '../list/InlineList';
import { type LiveVariables, resolveList } from '../list/slot';
import { objectPicker } from '../objectPick';
import type { EditorState, ValuesTarget } from '../state';

/** The asset or placed object whose variables `target` shows, when it still has any to show. */
function ownerOf(state: EditorState, target: Extract<ValuesTarget, { kind: 'variables' }>) {
  const { owner } = target;
  if (owner.kind === 'asset') {
    const asset = findAsset(state.project, owner.assetId);
    return isVariableOwner(asset) ? { asset, name: asset.name } : null;
  }
  const view = viewOf(state.project, owner.holderId);
  const object = view && findObject(view, owner.objectId);
  const asset = object && findAsset(state.project, object.assetId);
  return object && asset?.type === 'behavior' ? { asset, name: objectName(object, asset) } : null;
}

/** What the tab of `target` says, or null once there is nothing left to show – the tab closes then. */
export function valuesTitle(state: EditorState, target: ValuesTarget, live?: LiveVariables): string | null {
  if (target.kind === 'list') return resolveList(state, target.slot, live)?.title ?? null;
  const owner = ownerOf(state, target);
  if (!owner) return null;
  return `${owner.name} · ${owner.asset.type === 'struct' ? 'Fields' : 'Variables'}`;
}

export class VariablesEditor extends VStack {
  private readonly title = new Label('', { style: 'bodyBold' });
  private readonly scroll = new ScrollContainer();
  private host: InspectorHost;
  private target: ValuesTarget | null = null;
  private signature = '';
  private lastLiveRefresh = 0;
  private rebuildWhenLeft = false;
  private readonly releaseFocusHandler: () => void;
  /** The list a list target draws, and its head. */
  private list: { head: ListHead; items: InlineList } | null = null;
  /** A Variables asset's live values, set by the editor – the only place that knows the running worlds. */
  liveVariables: LiveVariables = () => null;

  constructor(private readonly state: EditorState) {
    super({ gap: 0 });
    const header = new HStack({ gap: Theme.gap, padding: Theme.padding, align: 'center' });
    header.minHeight = Theme.controlHeight + 2 * Theme.padding;
    header.add(this.title, 1);
    this.add(header);
    this.host = this.emptyHost();
    this.scroll.setContent(this.host.body);
    this.add(this.scroll, 1);
    state.on('project', () => this.refresh());
    state.on('runtime', () => this.refreshLive());
    this.releaseFocusHandler = ui().focus.onFocusChange(() => {
      if (this.rebuildWhenLeft && !ui().focus.isWithin(this)) this.rebuild();
    });
  }

  /** Signing out destroys the tab while the page stays up (#177), so the handler goes with it. */
  override destroy(options?: Parameters<VStack['destroy']>[0]): void {
    this.releaseFocusHandler();
    super.destroy(options);
  }

  /** Points the tab at another target; the one it showed keeps nothing, every edit is in the model. */
  show(target: ValuesTarget): void {
    this.target = target;
    this.rebuild();
  }

  /** For the check scripts: what the tab shows, and the lists drawn in it. */
  debugInfo(): { title: string; target: ValuesTarget | null; rows: string[] } {
    return {
      title: this.title.text,
      target: this.target,
      rows: [...this.host.fields.keys()],
    };
  }

  /** Every list drawn in the tab, at any depth. */
  lists(): InlineList[] {
    return inlineListsIn(this.host.body);
  }

  private emptyHost(): InspectorHost {
    return {
      state: this.state,
      project: () => this.state.project,
      liveVariables: (assetId) => this.liveVariables(assetId),
      body: new VStack({ padding: Theme.padding, gap: Theme.gap }),
      fields: new Map(),
      nameField: null,
    };
  }

  private currentSignature(): string {
    const target = this.target;
    if (!target) return '';
    if (target.kind === 'list') return resolveList(this.state, target.slot) ? 'list' : 'missing';
    const { owner } = target;
    if (!ownerOf(this.state, target)) return 'missing';
    return owner.kind === 'asset'
      ? assetSignature(this.state.project, owner.assetId)
      : objectSignature(this.state, owner.holderId, [owner.objectId], owner.objectId);
  }

  private rebuild(): void {
    this.rebuildWhenLeft = false;
    this.host.body.destroy({ children: true });
    this.host = this.emptyHost();
    this.list = null;
    this.signature = this.currentSignature();
    const target = this.target;
    this.title.setText((target && valuesTitle(this.state, target, this.liveVariables)) ?? '');
    if (target?.kind === 'list') this.buildList(target.slot);
    else if (target) {
      const owner = ownerOf(this.state, target);
      if (owner && target.owner.kind === 'asset') buildVariables(this.host, owner.asset, true);
      else if (target.owner.kind === 'object')
        buildOwnRows(this.host, target.owner.holderId, target.owner.objectId, true);
    }
    this.scroll.setContent(this.host.body);
  }

  private buildList(slot: Extract<ValuesTarget, { kind: 'list' }>['slot']): void {
    const access = () => resolveList(this.state, slot, this.liveVariables);
    if (slot.kind === 'object') {
      this.host.objectChoices = () => pickableObjects(this.state.project, slot.holderId, slot.objectId);
      this.host.objectPicker = objectPicker(
        this.state,
        slot.holderId,
        slot.objectId,
        this.host.objectChoices,
      );
    }
    const items = new InlineList(this.host, access);
    const head = new ListHead(access, (kind) => items.addItem(kind), false);
    items.head = head;
    this.host.body.add(head);
    this.host.body.add(items);
    this.list = { head, items };
  }

  /** Play mode: follow what the behaviors write, ~10× a second, but never under a field being typed in. */
  private refreshLive(): void {
    if (!this.visible) return;
    const now = performance.now();
    if (now - this.lastLiveRefresh < 100) return;
    if (ui().focus.isWithin(this)) return;
    this.lastLiveRefresh = now;
    this.refresh();
  }

  private refresh(): void {
    const target = this.target;
    if (!target) return;
    this.title.setText(valuesTitle(this.state, target, this.liveVariables) ?? '');
    if (this.currentSignature() !== this.signature) {
      if (ui().focus.isWithin(this)) {
        this.rebuildWhenLeft = true;
        return;
      }
      this.rebuild();
      return;
    }
    if (target.kind === 'list') {
      this.list?.head.setCount(this.list.items.access()?.value.length ?? 0);
      this.list?.items.refresh();
      return;
    }
    const { owner } = target;
    const ok =
      owner.kind === 'asset'
        ? refreshAssetSection(this.host, owner.assetId)
        : refreshObjectSection(this.host, owner.holderId, owner.objectId);
    if (!ok) this.rebuild();
  }
}

/** Every inline list below `root`, outermost first – what the check scripts pick one from. */
export function inlineListsIn(root: Container): InlineList[] {
  const found: InlineList[] = [];
  const walk = (node: Container): void => {
    if (node instanceof InlineList) found.push(node);
    for (const child of node.children) walk(child);
  };
  walk(root);
  return found;
}