import type {
  PublicRectificationMethod,
  PublicRectificationTool,
  RectificationActivityStatus,
} from "./rectification-agentic/v9/public-receipt";

export type CompletedActivityReceiptView = Readonly<{
  steps: readonly PublicRectificationTool[];
  methods: readonly PublicRectificationMethod[];
  failedTool?: PublicRectificationTool;
}>;

type ToolTerminalStatus = "completed" | "failed";

export type RectificationActivityReceiptState = Readonly<{
  completedSteps: readonly PublicRectificationTool[];
  methodsByTool: Readonly<Partial<Record<PublicRectificationTool, readonly PublicRectificationMethod[]>>>;
  terminalStatus: Readonly<Partial<Record<PublicRectificationTool, ToolTerminalStatus>>>;
  failureOrder: readonly PublicRectificationTool[];
}>;

type ReceiptActivityEvent = Readonly<{
  tool: PublicRectificationTool;
  status: RectificationActivityStatus;
  methods?: readonly PublicRectificationMethod[];
}>;

export function createRectificationActivityReceiptState(): RectificationActivityReceiptState {
  return {
    completedSteps: [],
    methodsByTool: {},
    terminalStatus: {},
    failureOrder: [],
  };
}

export function reduceRectificationActivityReceipt(
  state: RectificationActivityReceiptState,
  event: ReceiptActivityEvent,
): RectificationActivityReceiptState {
  if (event.status === "started") return state;

  const terminalStatus = { ...state.terminalStatus, [event.tool]: event.status };
  if (event.status === "completed") {
    return {
      completedSteps: state.completedSteps.includes(event.tool)
        ? state.completedSteps
        : [...state.completedSteps, event.tool],
      methodsByTool: {
        ...state.methodsByTool,
        [event.tool]: [...new Set(event.methods ?? [])],
      },
      terminalStatus,
      failureOrder: state.failureOrder.filter((tool) => tool !== event.tool),
    };
  }

  return {
    ...state,
    completedSteps: state.completedSteps.filter((tool) => tool !== event.tool),
    methodsByTool: { ...state.methodsByTool, [event.tool]: [] },
    terminalStatus,
    failureOrder: [
      ...state.failureOrder.filter((tool) => tool !== event.tool),
      event.tool,
    ],
  };
}

export function receiptFromRectificationActivityState(
  state: RectificationActivityReceiptState,
): CompletedActivityReceiptView {
  const failedTool = [...state.failureOrder]
    .reverse()
    .find((tool) => state.terminalStatus[tool] === "failed");
  return {
    steps: [...state.completedSteps],
    methods: [...new Set(state.completedSteps.flatMap((tool) => state.methodsByTool[tool] ?? []))],
    ...(failedTool ? { failedTool } : {}),
  };
}