import type { Command } from "./command";
import type { EditorState } from "@editor/state";
import { commandIds } from "./ids";

export const historyUndoCommand: Command = {
  id: commandIds.historyUndo,
  name: "Undo",
  history: { mode: "ignore" },
  execute({ state }) {
    const previous = state.history.past.at(-1);
    if (!previous) return state;

    return {
      ...state,
      document: previous.document,
      editor: preserveGenerationJobs(previous.editor, state.editor),
      history: {
        past: state.history.past.slice(0, -1),
        future: [{ document: state.document, editor: state.editor }, ...state.history.future],
      },
    };
  },
};

export const historyRedoCommand: Command = {
  id: commandIds.historyRedo,
  name: "Redo",
  history: { mode: "ignore" },
  execute({ state }) {
    const next = state.history.future[0];
    if (!next) return state;

    return {
      ...state,
      document: next.document,
      editor: preserveGenerationJobs(next.editor, state.editor),
      history: {
        past: [...state.history.past, { document: state.document, editor: state.editor }],
        future: state.history.future.slice(1),
      },
    };
  },
};

export const historyCommands = [historyUndoCommand, historyRedoCommand] satisfies Command<unknown>[];

function preserveGenerationJobs(target: EditorState, current: EditorState): EditorState {
  return {
    ...target,
    generation: {
      ...target.generation,
      jobs: current.generation.jobs,
    },
  };
}