import { newId } from '../ids';
import { isSelfOrAncestor, localPositionFor, removeSubtrees, worldPosition } from '../model/hierarchy';
import {
  captureObject,
  isLiveInstance,
  type ObjectMemo,
  type ObjectRef,
  restoreObject,
} from '../model/instance';
import { placementRejection } from '../model/placement';
import { type Position, type PropertyValue, toPosition, type Vec2 } from '../model/Properties';
import type { Project } from '../model/Project';
import { createSceneObject, type SceneObject } from '../model/SceneObject';
import { coerceValue } from '../properties/PropertySchema';
import { type Removed, restoreAt } from '../util/list';
import { type Command, CommandError } from './Command';
import {
  requireAsset,
  requireObject,
  requireObjectRef,
  requirePropDef,
  requireHolder,
  requireStructuralObject,
} from './require';

/**
 * An edit to one placed object. The base captures the object before the edit and puts it back on
 * undo, so a subclass only says what changes – and, if it wrote somewhere else too, how to take
 * that back (`revert`).
 */
export abstract class ObjectEditCommand implements Command {
  abstract readonly label: string;
  private memo: ObjectMemo | undefined;

  protected constructor(
    private readonly holderId: string,
    private readonly objectId: string,
  ) {}

  protected abstract apply(ref: ObjectRef, project: Project): void;

  protected revert(): void {}

  execute(project: Project): void {
    const ref = requireObjectRef(project, this.holderId, this.objectId);
    this.memo = captureObject(ref);
    this.apply(ref, project);
  }

  undo(): void {
    this.revert();
    if (this.memo) restoreObject(this.memo);
  }
}

/**
 * The position is a world position; with a parent it is converted to the parent's local space.
 * Placing a container adds the container object alone – its content is resolved from the template
 * (see `model/instance.ts`), so it is never copied into the scene.
 */
export class PlaceAssetCommand implements Command {
  readonly label = 'Place asset';
  readonly objectId = newId();

  constructor(
    private readonly holderId: string,
    private readonly assetId: string,
    private readonly position: Vec2 | Position,
    private readonly parentId = '',
  ) {}

  execute(project: Project): void {
    const holder = requireHolder(project, this.holderId);
    const asset = requireAsset(project, this.assetId);
    const rejection = placementRejection(project, holder, asset);
    if (rejection) throw new CommandError(rejection);
    if (this.parentId) requireStructuralObject(project, holder, this.parentId);
    const local = localPositionFor(holder, this.parentId, toPosition(this.position));
    holder.objects.push(createSceneObject(this.objectId, this.assetId, local, this.parentId));
  }

  undo(project: Project): void {
    const holder = requireHolder(project, this.holderId);
    holder.objects = holder.objects.filter((o) => o.id !== this.objectId);
  }
}

/** Removes objects together with everything parented below them, as one undo step. */
export class RemoveSceneObjectsCommand implements Command {
  readonly label: string;
  private removed: Removed<SceneObject>[] = [];

  constructor(
    private readonly holderId: string,
    private readonly objectIds: readonly string[],
  ) {
    this.label = objectIds.length === 1 ? 'Remove object' : 'Remove objects';
  }

  execute(project: Project): void {
    const holder = requireHolder(project, this.holderId);
    for (const id of this.objectIds) requireStructuralObject(project, holder, id);
    this.removed = removeSubtrees(holder, this.objectIds);
  }

  undo(project: Project): void {
    restoreAt(requireHolder(project, this.holderId).objects, this.removed);
  }
}

/**
 * The previous position is read at execution time, so a caller that previewed the move must
 * restore the model before executing.
 */
export class MoveSceneObjectCommand extends ObjectEditCommand {
  readonly label = 'Move object';

  constructor(
    holderId: string,
    objectId: string,
    private readonly position: Position,
  ) {
    super(holderId, objectId);
  }

  protected override apply(ref: ObjectRef): void {
    ref.setPosition(this.position);
  }
}

/** Editor-only: undoable like any other edit, but it changes nothing the game can see. */
export class SetEditorOffsetCommand extends ObjectEditCommand {
  readonly label = 'Editor offset';

  constructor(
    holderId: string,
    objectId: string,
    private readonly offset: Vec2,
  ) {
    super(holderId, objectId);
  }

  protected override apply(ref: ObjectRef): void {
    ref.setEditorOffset(this.offset);
  }
}

export class RenameSceneObjectCommand extends ObjectEditCommand {
  readonly label = 'Rename object';

  constructor(
    holderId: string,
    objectId: string,
    private readonly name: string,
  ) {
    super(holderId, objectId);
  }

  protected override apply(ref: ObjectRef): void {
    ref.setName(this.name);
  }
}

abstract class OverrideCommand extends ObjectEditCommand {
  protected constructor(
    holderId: string,
    objectId: string,
    protected readonly key: string,
    readonly label: string,
  ) {
    super(holderId, objectId);
  }

  protected abstract nextValue(object: SceneObject, project: Project): PropertyValue | undefined;

  protected override apply(ref: ObjectRef, project: Project): void {
    ref.setOverride(this.key, this.nextValue(ref.object, project));
  }
}

export class SetOverrideCommand extends OverrideCommand {
  constructor(
    holderId: string,
    objectId: string,
    key: string,
    private readonly value: PropertyValue,
  ) {
    super(holderId, objectId, key, `Override ${key}`);
  }

  protected override nextValue(object: SceneObject, project: Project): PropertyValue {
    return coerceValue(
      requirePropDef(project, requireAsset(project, object.assetId), this.key, object),
      this.value,
    );
  }
}

export class ClearOverrideCommand extends OverrideCommand {
  constructor(holderId: string, objectId: string, key: string) {
    super(holderId, objectId, key, `Reset ${key}`);
  }

  // No schema check, unlike setting one: a key the asset no longer declares is exactly what one
  // wants to be able to clear.
  protected override nextValue(): undefined {
    return undefined;
  }
}

/**
 * Moves an object among its siblings. Sibling order is the order the stored list happens to have
 * (`treeOrder`), so the move is a splice – and because objects sharing a `z` fall back to that
 * order, it is also how two overlapping objects are put in front of each other.
 */
export class ReorderObjectCommand implements Command {
  readonly label = 'Reorder object';
  private previousIndex = -1;

  /** `beforeId` empty means "behind its last sibling". */
  constructor(
    private readonly holderId: string,
    private readonly objectId: string,
    private readonly beforeId: string,
  ) {}

  execute(project: Project): void {
    const holder = requireHolder(project, this.holderId);
    const object = requireStructuralObject(project, holder, this.objectId);
    if (this.beforeId === this.objectId)
      throw new CommandError('An object cannot be moved in front of itself');
    let at = holder.objects.length;
    if (this.beforeId) {
      const before = requireStructuralObject(project, holder, this.beforeId);
      if (before.parentId !== object.parentId)
        throw new CommandError('An object can only be reordered among its own siblings');
      at = holder.objects.indexOf(before);
    }
    this.previousIndex = holder.objects.indexOf(object);
    holder.objects.splice(this.previousIndex, 1);
    // The index was read before the removal, so anything behind it has moved up by one.
    holder.objects.splice(at > this.previousIndex ? at - 1 : at, 0, object);
  }

  undo(project: Project): void {
    const holder = requireHolder(project, this.holderId);
    const object = requireObject(project, this.holderId, this.objectId);
    holder.objects.splice(holder.objects.indexOf(object), 1);
    holder.objects.splice(this.previousIndex, 0, object);
  }
}

/**
 * Re-parents an object ('' = top level). It keeps its world position: the local one is recomputed
 * for the new parent.
 */
export class SetParentCommand implements Command {
  readonly label = 'Set parent';
  private previous: { parentId: string; position: Position } = {
    parentId: '',
    position: { x: 0, y: 0, z: 0 },
  };

  constructor(
    private readonly holderId: string,
    private readonly objectId: string,
    private readonly parentId: string,
  ) {}

  execute(project: Project): void {
    const holder = requireHolder(project, this.holderId);
    const object = requireStructuralObject(project, holder, this.objectId);
    if (this.parentId) {
      if (this.parentId === this.objectId) throw new CommandError('An object cannot be its own parent');
      if (isLiveInstance(project, holder, requireStructuralObject(project, holder, this.parentId)))
        throw new CommandError('A placed container shows its template; unpack it to put objects inside');
      if (isSelfOrAncestor(holder, this.objectId, this.parentId))
        throw new CommandError('An object cannot be parented to one of its own children');
    }
    this.previous = { parentId: object.parentId, position: { ...object.position } };
    const world = worldPosition(holder, object);
    object.parentId = this.parentId;
    object.position = localPositionFor(holder, this.parentId, world);
  }

  undo(project: Project): void {
    const object = requireObject(project, this.holderId, this.objectId);
    object.parentId = this.previous.parentId;
    object.position = { ...this.previous.position };
  }
}