/**
 * Copy and paste of placed objects and graph pieces (#240). The clipboard is the editor's own: a
 * copy names assets of this project, which mean nothing anywhere else.
 */
import { PasteGraphCommand, PasteObjectsCommand } from '../core/commands/pasteCommands';
import {
  BEHAVIOR_PARAM,
  findAnnotation,
  findNode,
  type GraphNode,
  nodeDef,
  RUN_BEHAVIOR,
} from '../core/graph';
import type { GraphAsset } from '../core/model/Asset';
import { type Clip, copyGraph, copyObjects, type GraphClip, type ObjectClip } from '../core/model/clipboard';
import { findObject } from '../core/model/hierarchy';
import { isLiveInstance } from '../core/model/instance';
import type { Vec2 } from '../core/model/Properties';
import { findGraphAsset, findObjectHolder, type ObjectHolder, type Project } from '../core/model/Project';
import { GRID_STEP } from './graph/graphView';
import { paletteEntries } from './graph/paletteEntries';
import { type EditorState, graphSelection, objectSelection } from './state';
import { SCENE_GRID_STEP } from './viewport/sceneViewHost';

/**
 * `lineage` holds the originals and everything pasted from them since: selecting one of those and
 * pasting puts the copy beside it, not inside it. `pastes` holds one id per paste; those still there
 * stagger the next paste that lands without a pointer, so an undone paste frees its spot again.
 */
export interface EditorClipboard {
  clip: Clip;
  lineage: Set<string>;
  pastes: string[];
}

function put(state: EditorState, clip: Clip, lineage: Iterable<string>, noun: string): true {
  state.clipboard = { clip, lineage: new Set(lineage), pastes: [] };
  state.setNotice(`Copied ${noun}`);
  return true;
}

function counted(count: number, one: string): string {
  return count === 1 ? `1 ${one}` : `${count} ${one}s`;
}

/** Copies the objects with everything below them; false when none of them is there. */
export function copyObjectIds(state: EditorState, holderId: string, ids: readonly string[]): boolean {
  const holder = findObjectHolder(state.project, holderId);
  const clip = holder && copyObjects(state.project, holder, ids);
  if (!clip) return false;
  const roots = clip.roots.map((r) => r.id);
  return put(state, clip, roots, counted(roots.length, 'object'));
}

/** Copies the selected objects, or the selected nodes and boxes; false when nothing of that is selected. */
export function copySelection(state: EditorState): boolean {
  const s = state.selection;
  if (s?.kind === 'object') return copyObjectIds(state, s.holderId, s.objectIds);
  if (s?.kind === 'node' || s?.kind === 'annotation') {
    const graph = findGraphAsset(state.project, s.assetId)?.graph;
    const nodeIds = s.kind === 'node' ? s.nodeIds : [];
    const clip = graph && copyGraph(graph, nodeIds, s.annotationIds);
    if (!clip) return false;
    return put(state, clip, [], counted(clip.nodes.length + clip.annotations.length, 'item'));
  }
  return false;
}

function objectClip(state: EditorState): ObjectClip | null {
  const clip = state.clipboard?.clip;
  return clip?.kind === 'objects' ? clip : null;
}

function graphClip(state: EditorState): GraphClip | null {
  const clip = state.clipboard?.clip;
  return clip?.kind === 'graph' ? clip : null;
}

export function canPasteObjects(state: EditorState): boolean {
  return objectClip(state) !== null;
}

export function canPasteGraph(state: EditorState): boolean {
  return graphClip(state) !== null;
}

/** Whether an object may take children: stored in the holder, and not a container showing its template. */
function takesChildren(project: Project, holder: ObjectHolder, id: string): boolean {
  const object = findObject(holder, id);
  return object !== undefined && !isLiveInstance(project, holder, object);
}

/** The one selected object of `holderId`; empty when there are none or several. */
function pickedObject(state: EditorState, holderId: string): string {
  const s = state.selection;
  return s?.kind === 'object' && s.holderId === holderId && s.objectIds.length === 1 ? s.objectId : '';
}

/**
 * Where each copied root goes. Into the `picked` object when there is one; beside it when that one
 * is an original or an earlier paste; otherwise under the parent it had, if this holder has it,
 * else on top.
 */
function pasteParents(
  project: Project,
  holder: ObjectHolder,
  clip: ObjectClip,
  lineage: ReadonlySet<string>,
  picked: string,
): Record<string, string> {
  let into: string | null = null;
  if (picked && lineage.has(picked)) {
    const parentId = findObject(holder, picked)?.parentId ?? '';
    into = parentId && takesChildren(project, holder, parentId) ? parentId : '';
  } else if (picked && takesChildren(project, holder, picked)) into = picked;
  const parents: Record<string, string> = {};
  for (const root of clip.roots) {
    const own = clip.objects.find((o) => o.id === root.id)?.parentId ?? '';
    parents[root.id] = into ?? (own && takesChildren(project, holder, own) ? own : '');
  }
  return parents;
}

/**
 * Pastes the copied objects into `holderId`, into or beside `picked` – by default the one selected
 * object. With `pointer` (world units) the copy is centred on it, otherwise it lands a step beside
 * the original, a step further for every earlier paste still there.
 */
export function pasteObjects(
  state: EditorState,
  holderId: string,
  pointer: Vec2 | null,
  picked = pickedObject(state, holderId),
): boolean {
  const board = state.clipboard;
  const clip = objectClip(state);
  const holder = findObjectHolder(state.project, holderId);
  // Nothing of the right kind lets the key through: Ctrl+V then imports an image, as it always did.
  if (!board || !clip || !holder) return false;
  const centred =
    pointer &&
    centredOn(
      pointer,
      clip.roots.map((r) => ({ x: r.world.x, y: r.world.y, w: 0, h: 0 })),
    );
  const shift = centred
    ? { x: Math.round(centred.x), y: Math.round(centred.y) }
    : stepped(board.pastes.filter((id) => findObject(holder, id)).length, SCENE_GRID_STEP);
  const parents = pasteParents(state.project, holder, clip, board.lineage, picked);
  const command = new PasteObjectsCommand(holderId, clip, parents, shift);
  if (!state.execute(command)) return false;
  board.pastes.push(command.rootIds[0]!);
  for (const id of command.rootIds) board.lineage.add(id);
  state.select(objectSelection(holderId, command.rootIds));
  return true;
}

/** Whether `asset`'s graph may hold `node`: the palette would offer its kind there. */
function fitsGraph(project: Project, asset: GraphAsset, node: GraphNode): boolean {
  return paletteEntries(project, asset).some(
    (entry) =>
      entry.def.type === node.type &&
      (node.type !== RUN_BEHAVIOR || entry.params[BEHAVIOR_PARAM] === node.params[BEHAVIOR_PARAM]),
  );
}

/** The part of a graph copy `asset` can take, and the nodes it cannot. */
function fittingPart(
  project: Project,
  asset: GraphAsset,
  clip: GraphClip,
): { clip: GraphClip; skipped: GraphNode[] } {
  const nodes = clip.nodes.filter((n) => fitsGraph(project, asset, n));
  const kept = new Set(nodes.map((n) => n.id));
  return {
    clip: {
      ...clip,
      nodes,
      edges: clip.edges.filter((e) => kept.has(e.from.node) && kept.has(e.to.node)),
    },
    skipped: clip.nodes.filter((n) => !kept.has(n.id)),
  };
}

/**
 * Pastes the copied nodes and boxes into `assetId`'s graph, at `pointer` (graph units) or a grid
 * step beside the original. `snap` keeps a pointer paste on the grid. What the graph cannot take is
 * left out and named.
 */
export function pasteGraph(
  state: EditorState,
  assetId: string,
  pointer: Vec2 | null,
  snap: boolean,
): boolean {
  const board = state.clipboard;
  const clip = graphClip(state);
  const asset = findGraphAsset(state.project, assetId);
  if (!board || !clip || !asset) return false;
  const part = fittingPart(state.project, asset, clip);
  const skipped = [...new Set(part.skipped.map((n) => nodeDef(n.type)?.label ?? n.type))].join(', ');
  if (part.clip.nodes.length === 0 && part.clip.annotations.length === 0) {
    state.setNotice(`Nothing of the copy fits into this graph (${skipped})`);
    return false;
  }
  const standing = board.pastes.filter((id) => findNode(asset.graph, id) || findAnnotation(asset.graph, id));
  let shift = stepped(standing.length, GRID_STEP);
  if (pointer) {
    shift = centredOn(pointer, [
      ...part.clip.nodes.map((n) => ({ x: n.x, y: n.y, w: 0, h: 0 })),
      ...part.clip.annotations.map((a) => a.annotation),
    ]);
    if (snap) shift = { x: snapped(shift.x), y: snapped(shift.y) };
  }
  const command = new PasteGraphCommand(assetId, part.clip, shift);
  if (!state.execute(command)) return false;
  board.pastes.push(command.nodeIds[0] ?? command.annotationIds[0]!);
  state.select(graphSelection(assetId, command.nodeIds, command.annotationIds));
  if (skipped) state.setNotice(`Pasted without what this graph cannot take: ${skipped}`);
  return true;
}

function snapped(value: number): number {
  return Math.round(value / GRID_STEP) * GRID_STEP;
}

/** One step down and right per paste still standing, and one more for this one. */
function stepped(standing: number, step: number): Vec2 {
  const by = step * (standing + 1);
  return { x: by, y: by };
}

/** The shift that puts the middle of the boxes' bounds on `at`. */
function centredOn(at: Vec2, boxes: readonly { x: number; y: number; w: number; h: number }[]): Vec2 {
  const minX = Math.min(...boxes.map((b) => b.x));
  const minY = Math.min(...boxes.map((b) => b.y));
  const maxX = Math.max(...boxes.map((b) => b.x + b.w));
  const maxY = Math.max(...boxes.map((b) => b.y + b.h));
  return { x: at.x - (minX + maxX) / 2, y: at.y - (minY + maxY) / 2 };
}