import crypto from "node:crypto";
import type { SerializedProjectCommand } from "./project-command.model.js";

export const projectBuildingInsertCommandType = "project-building.insert" as const;
export const projectBuildingDeleteCommandType = "project-building.delete" as const;
export const projectBuildingUpdateCommandType = "project-building.update" as const;
export const projectFloorInsertCommandType = "project-floor.insert" as const;
export const projectFloorDeleteCommandType = "project-floor.delete" as const;
export const projectFloorUpdateCommandType = "project-floor.update" as const;
export const projectRoomInsertCommandType = "project-room.insert" as const;
export const projectRoomDeleteCommandType = "project-room.delete" as const;
export const projectRoomUpdateCommandType = "project-room.update" as const;
/** Room commands, building commands and legacy floor commands. */
export const projectLocationStructureCommandSchemaVersion = 1 as const;
/**
 * Floor commands carry `buildingId` since version 2. Version 1 floor
 * commands stay executable from persisted history: they were recorded before
 * buildings existed, so they are upgraded with `buildingId = null`.
 */
export const projectFloorCommandSchemaVersion = 2 as const;
const legacyProjectFloorCommandSchemaVersion = 1 as const;

export interface ProjectBuildingSnapshot {
  id: string;
  projectId: string;
  name: string;
  sortOrder: number;
}

export interface ProjectFloorSnapshot {
  id: string;
  projectId: string;
  name: string;
  sortOrder: number;
  buildingId: string | null;
}

export type LegacyProjectFloorSnapshot = Omit<ProjectFloorSnapshot, "buildingId">;

export interface ProjectRoomSnapshot {
  id: string;
  projectId: string;
  floorId: string | null;
  roomNumber: string;
  roomName: string;
}

interface ProjectBuildingStructureCommandPayload {
  building: ProjectBuildingSnapshot;
}

interface ProjectFloorStructureCommandPayload {
  floor: ProjectFloorSnapshot;
}

interface LegacyProjectFloorStructureCommandPayload {
  floor: LegacyProjectFloorSnapshot;
}

interface ProjectRoomStructureCommandPayload {
  room: ProjectRoomSnapshot;
}

interface ProjectBuildingUpdateCommandPayload {
  expected: ProjectBuildingSnapshot;
  target: ProjectBuildingSnapshot;
}

interface ProjectFloorUpdateCommandPayload {
  expected: ProjectFloorSnapshot;
  target: ProjectFloorSnapshot;
}

interface LegacyProjectFloorUpdateCommandPayload {
  expected: LegacyProjectFloorSnapshot;
  target: LegacyProjectFloorSnapshot;
}

interface ProjectRoomUpdateCommandPayload {
  expected: ProjectRoomSnapshot;
  target: ProjectRoomSnapshot;
}

export interface ProjectBuildingInsertProjectCommand
  extends SerializedProjectCommand<ProjectBuildingStructureCommandPayload> {
  schemaVersion: typeof projectLocationStructureCommandSchemaVersion;
  type: typeof projectBuildingInsertCommandType;
}

export interface ProjectBuildingDeleteProjectCommand
  extends SerializedProjectCommand<ProjectBuildingStructureCommandPayload> {
  schemaVersion: typeof projectLocationStructureCommandSchemaVersion;
  type: typeof projectBuildingDeleteCommandType;
}

export interface ProjectBuildingUpdateProjectCommand
  extends SerializedProjectCommand<ProjectBuildingUpdateCommandPayload> {
  schemaVersion: typeof projectLocationStructureCommandSchemaVersion;
  type: typeof projectBuildingUpdateCommandType;
}

export interface ProjectFloorInsertProjectCommand
  extends SerializedProjectCommand<ProjectFloorStructureCommandPayload> {
  schemaVersion: typeof projectFloorCommandSchemaVersion;
  type: typeof projectFloorInsertCommandType;
}

export interface ProjectFloorDeleteProjectCommand
  extends SerializedProjectCommand<ProjectFloorStructureCommandPayload> {
  schemaVersion: typeof projectFloorCommandSchemaVersion;
  type: typeof projectFloorDeleteCommandType;
}

export interface ProjectFloorUpdateProjectCommand
  extends SerializedProjectCommand<ProjectFloorUpdateCommandPayload> {
  schemaVersion: typeof projectFloorCommandSchemaVersion;
  type: typeof projectFloorUpdateCommandType;
}

export interface LegacyProjectFloorInsertProjectCommand
  extends SerializedProjectCommand<LegacyProjectFloorStructureCommandPayload> {
  schemaVersion: typeof legacyProjectFloorCommandSchemaVersion;
  type: typeof projectFloorInsertCommandType;
}

export interface LegacyProjectFloorDeleteProjectCommand
  extends SerializedProjectCommand<LegacyProjectFloorStructureCommandPayload> {
  schemaVersion: typeof legacyProjectFloorCommandSchemaVersion;
  type: typeof projectFloorDeleteCommandType;
}

export interface LegacyProjectFloorUpdateProjectCommand
  extends SerializedProjectCommand<LegacyProjectFloorUpdateCommandPayload> {
  schemaVersion: typeof legacyProjectFloorCommandSchemaVersion;
  type: typeof projectFloorUpdateCommandType;
}

export interface ProjectRoomInsertProjectCommand
  extends SerializedProjectCommand<ProjectRoomStructureCommandPayload> {
  schemaVersion: typeof projectLocationStructureCommandSchemaVersion;
  type: typeof projectRoomInsertCommandType;
}

export interface ProjectRoomDeleteProjectCommand
  extends SerializedProjectCommand<ProjectRoomStructureCommandPayload> {
  schemaVersion: typeof projectLocationStructureCommandSchemaVersion;
  type: typeof projectRoomDeleteCommandType;
}

export interface ProjectRoomUpdateProjectCommand
  extends SerializedProjectCommand<ProjectRoomUpdateCommandPayload> {
  schemaVersion: typeof projectLocationStructureCommandSchemaVersion;
  type: typeof projectRoomUpdateCommandType;
}

export type ProjectLocationStructureProjectCommand =
  | ProjectBuildingInsertProjectCommand
  | ProjectBuildingDeleteProjectCommand
  | ProjectBuildingUpdateProjectCommand
  | ProjectFloorInsertProjectCommand
  | ProjectFloorDeleteProjectCommand
  | ProjectFloorUpdateProjectCommand
  | LegacyProjectFloorInsertProjectCommand
  | LegacyProjectFloorDeleteProjectCommand
  | LegacyProjectFloorUpdateProjectCommand
  | ProjectRoomInsertProjectCommand
  | ProjectRoomDeleteProjectCommand
  | ProjectRoomUpdateProjectCommand;

export function createProjectBuildingSnapshot(
  projectId: string,
  name: string,
  sortOrder: number
): ProjectBuildingSnapshot {
  const building: ProjectBuildingSnapshot = {
    id: crypto.randomUUID(),
    projectId,
    name: name.trim(),
    sortOrder,
  };
  assertProjectBuildingSnapshot(building);
  return building;
}

export function createProjectFloorSnapshot(
  projectId: string,
  name: string,
  sortOrder: number,
  buildingId: string | null = null
): ProjectFloorSnapshot {
  const floor: ProjectFloorSnapshot = {
    id: crypto.randomUUID(),
    projectId,
    name: name.trim(),
    sortOrder,
    buildingId: buildingId?.trim() || null,
  };
  assertProjectFloorSnapshot(floor);
  return floor;
}

export function createProjectRoomSnapshot(
  projectId: string,
  input: {
    floorId?: string;
    roomNumber: string;
    roomName: string;
  }
): ProjectRoomSnapshot {
  const room: ProjectRoomSnapshot = {
    id: crypto.randomUUID(),
    projectId,
    floorId: input.floorId?.trim() || null,
    roomNumber: input.roomNumber.trim(),
    roomName: input.roomName.trim(),
  };
  assertProjectRoomSnapshot(room);
  return room;
}

export function createProjectBuildingInsertProjectCommand(
  building: ProjectBuildingSnapshot
): ProjectBuildingInsertProjectCommand {
  assertProjectBuildingSnapshot(building);
  return {
    schemaVersion: projectLocationStructureCommandSchemaVersion,
    type: projectBuildingInsertCommandType,
    payload: { building },
  };
}

export function createProjectBuildingDeleteProjectCommand(
  building: ProjectBuildingSnapshot
): ProjectBuildingDeleteProjectCommand {
  assertProjectBuildingSnapshot(building);
  return {
    schemaVersion: projectLocationStructureCommandSchemaVersion,
    type: projectBuildingDeleteCommandType,
    payload: { building },
  };
}

export function createProjectBuildingUpdateProjectCommand(
  expected: ProjectBuildingSnapshot,
  target: ProjectBuildingSnapshot
): ProjectBuildingUpdateProjectCommand {
  assertMatchingBuildingUpdate(expected, target);
  return {
    schemaVersion: projectLocationStructureCommandSchemaVersion,
    type: projectBuildingUpdateCommandType,
    payload: { expected, target },
  };
}

export function createProjectFloorInsertProjectCommand(
  floor: ProjectFloorSnapshot
): ProjectFloorInsertProjectCommand {
  assertProjectFloorSnapshot(floor);
  return {
    schemaVersion: projectFloorCommandSchemaVersion,
    type: projectFloorInsertCommandType,
    payload: { floor },
  };
}

export function createProjectFloorDeleteProjectCommand(
  floor: ProjectFloorSnapshot
): ProjectFloorDeleteProjectCommand {
  assertProjectFloorSnapshot(floor);
  return {
    schemaVersion: projectFloorCommandSchemaVersion,
    type: projectFloorDeleteCommandType,
    payload: { floor },
  };
}

export function createProjectRoomInsertProjectCommand(
  room: ProjectRoomSnapshot
): ProjectRoomInsertProjectCommand {
  assertProjectRoomSnapshot(room);
  return {
    schemaVersion: projectLocationStructureCommandSchemaVersion,
    type: projectRoomInsertCommandType,
    payload: { room },
  };
}

export function createProjectRoomDeleteProjectCommand(
  room: ProjectRoomSnapshot
): ProjectRoomDeleteProjectCommand {
  assertProjectRoomSnapshot(room);
  return {
    schemaVersion: projectLocationStructureCommandSchemaVersion,
    type: projectRoomDeleteCommandType,
    payload: { room },
  };
}

export function createProjectFloorUpdateProjectCommand(
  expected: ProjectFloorSnapshot,
  target: ProjectFloorSnapshot
): ProjectFloorUpdateProjectCommand {
  assertMatchingFloorUpdate(expected, target);
  return {
    schemaVersion: projectFloorCommandSchemaVersion,
    type: projectFloorUpdateCommandType,
    payload: { expected, target },
  };
}

export function createProjectRoomUpdateProjectCommand(
  expected: ProjectRoomSnapshot,
  target: ProjectRoomSnapshot
): ProjectRoomUpdateProjectCommand {
  assertMatchingRoomUpdate(expected, target);
  return {
    schemaVersion: projectLocationStructureCommandSchemaVersion,
    type: projectRoomUpdateCommandType,
    payload: { expected, target },
  };
}

export function assertProjectBuildingInsertProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is ProjectBuildingInsertProjectCommand {
  assertProjectBuildingStructureProjectCommand(
    command,
    projectBuildingInsertCommandType
  );
}

export function assertProjectBuildingDeleteProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is ProjectBuildingDeleteProjectCommand {
  assertProjectBuildingStructureProjectCommand(
    command,
    projectBuildingDeleteCommandType
  );
}

export function assertProjectBuildingUpdateProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is ProjectBuildingUpdateProjectCommand {
  if (
    command.schemaVersion !== projectLocationStructureCommandSchemaVersion ||
    command.type !== projectBuildingUpdateCommandType ||
    !isPlainObject(command.payload) ||
    Object.keys(command.payload).length !== 2
  ) {
    throw new Error("Unsupported project-building update command.");
  }
  assertMatchingBuildingUpdate(command.payload.expected, command.payload.target);
}

export function assertProjectFloorInsertProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is
  | ProjectFloorInsertProjectCommand
  | LegacyProjectFloorInsertProjectCommand {
  assertProjectFloorStructureProjectCommand(
    command,
    projectFloorInsertCommandType
  );
}

export function assertProjectFloorDeleteProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is
  | ProjectFloorDeleteProjectCommand
  | LegacyProjectFloorDeleteProjectCommand {
  assertProjectFloorStructureProjectCommand(
    command,
    projectFloorDeleteCommandType
  );
}

export function assertProjectRoomInsertProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is ProjectRoomInsertProjectCommand {
  assertProjectRoomStructureProjectCommand(
    command,
    projectRoomInsertCommandType
  );
}

export function assertProjectRoomDeleteProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is ProjectRoomDeleteProjectCommand {
  assertProjectRoomStructureProjectCommand(
    command,
    projectRoomDeleteCommandType
  );
}

export function assertProjectFloorUpdateProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is
  | ProjectFloorUpdateProjectCommand
  | LegacyProjectFloorUpdateProjectCommand {
  if (
    command.type !== projectFloorUpdateCommandType ||
    !isPlainObject(command.payload) ||
    Object.keys(command.payload).length !== 2
  ) {
    throw new Error("Unsupported project-floor update command.");
  }
  if (command.schemaVersion === legacyProjectFloorCommandSchemaVersion) {
    assertMatchingFloorUpdate(
      upgradeLegacyFloorSnapshot(command.payload.expected),
      upgradeLegacyFloorSnapshot(command.payload.target)
    );
    return;
  }
  if (command.schemaVersion !== projectFloorCommandSchemaVersion) {
    throw new Error("Unsupported project-floor update command.");
  }
  assertMatchingFloorUpdate(command.payload.expected, command.payload.target);
}

export function assertProjectRoomUpdateProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is ProjectRoomUpdateProjectCommand {
  if (
    command.schemaVersion !== projectLocationStructureCommandSchemaVersion ||
    command.type !== projectRoomUpdateCommandType ||
    !isPlainObject(command.payload) ||
    Object.keys(command.payload).length !== 2
  ) {
    throw new Error("Unsupported project-room update command.");
  }
  assertMatchingRoomUpdate(command.payload.expected, command.payload.target);
}

/**
 * Upgrades a (validated) floor command of any supported version to the
 * current version. Version 1 commands predate buildings; their floors had no
 * building, so `buildingId` becomes null.
 */
export function upgradeProjectFloorCommand(
  command:
    | ProjectFloorInsertProjectCommand
    | LegacyProjectFloorInsertProjectCommand
): ProjectFloorInsertProjectCommand;
export function upgradeProjectFloorCommand(
  command:
    | ProjectFloorDeleteProjectCommand
    | LegacyProjectFloorDeleteProjectCommand
): ProjectFloorDeleteProjectCommand;
export function upgradeProjectFloorCommand(
  command:
    | ProjectFloorUpdateProjectCommand
    | LegacyProjectFloorUpdateProjectCommand
): ProjectFloorUpdateProjectCommand;
export function upgradeProjectFloorCommand(
  command:
    | ProjectFloorInsertProjectCommand
    | ProjectFloorDeleteProjectCommand
    | ProjectFloorUpdateProjectCommand
    | LegacyProjectFloorInsertProjectCommand
    | LegacyProjectFloorDeleteProjectCommand
    | LegacyProjectFloorUpdateProjectCommand
) {
  if (command.schemaVersion === projectFloorCommandSchemaVersion) {
    return command;
  }
  switch (command.type) {
    case projectFloorInsertCommandType:
      return createProjectFloorInsertProjectCommand(
        upgradeLegacyFloorSnapshot(command.payload.floor)
      );
    case projectFloorDeleteCommandType:
      return createProjectFloorDeleteProjectCommand(
        upgradeLegacyFloorSnapshot(command.payload.floor)
      );
    case projectFloorUpdateCommandType:
      return createProjectFloorUpdateProjectCommand(
        upgradeLegacyFloorSnapshot(command.payload.expected),
        upgradeLegacyFloorSnapshot(command.payload.target)
      );
  }
}

function assertMatchingBuildingUpdate(expected: unknown, target: unknown) {
  assertProjectBuildingSnapshot(expected);
  assertProjectBuildingSnapshot(target);
  if (
    expected.id !== target.id ||
    expected.projectId !== target.projectId ||
    expected.sortOrder !== target.sortOrder ||
    expected.name === target.name
  ) {
    throw new Error("Project-building update must change only the name.");
  }
}

function assertMatchingFloorUpdate(expected: unknown, target: unknown) {
  assertProjectFloorSnapshot(expected);
  assertProjectFloorSnapshot(target);
  if (
    expected.id !== target.id ||
    expected.projectId !== target.projectId ||
    expected.sortOrder !== target.sortOrder ||
    (expected.name === target.name && expected.buildingId === target.buildingId)
  ) {
    throw new Error(
      "Project-floor update must change only the name or the building."
    );
  }
}

function assertMatchingRoomUpdate(expected: unknown, target: unknown) {
  assertProjectRoomSnapshot(expected);
  assertProjectRoomSnapshot(target);
  if (
    expected.id !== target.id ||
    expected.projectId !== target.projectId ||
    sameSnapshot(expected, target)
  ) {
    throw new Error("Project-room update must change room values.");
  }
}

export function assertProjectBuildingSnapshot(
  building: unknown
): asserts building is ProjectBuildingSnapshot {
  if (!isPlainObject(building) || Object.keys(building).length !== 4) {
    throw new Error("Project-building snapshot is invalid.");
  }
  assertNormalizedNonEmptyString(building.id, "building.id");
  assertNormalizedNonEmptyString(building.projectId, "building.projectId");
  assertNormalizedNonEmptyString(building.name, "building.name");
  assertSortOrder(building.sortOrder, "building.sortOrder");
}

export function assertProjectFloorSnapshot(
  floor: unknown
): asserts floor is ProjectFloorSnapshot {
  if (!isPlainObject(floor) || Object.keys(floor).length !== 5) {
    throw new Error("Project-floor snapshot is invalid.");
  }
  assertLegacyFloorFields(floor);
  if (floor.buildingId !== null) {
    assertNormalizedNonEmptyString(floor.buildingId, "floor.buildingId");
  }
}

function assertLegacyProjectFloorSnapshot(
  floor: unknown
): asserts floor is LegacyProjectFloorSnapshot {
  if (!isPlainObject(floor) || Object.keys(floor).length !== 4) {
    throw new Error("Project-floor snapshot is invalid.");
  }
  assertLegacyFloorFields(floor);
}

function assertLegacyFloorFields(floor: Record<string, unknown>) {
  assertNormalizedNonEmptyString(floor.id, "floor.id");
  assertNormalizedNonEmptyString(floor.projectId, "floor.projectId");
  assertNormalizedNonEmptyString(floor.name, "floor.name");
  assertSortOrder(floor.sortOrder, "floor.sortOrder");
}

function upgradeLegacyFloorSnapshot(floor: unknown): ProjectFloorSnapshot {
  assertLegacyProjectFloorSnapshot(floor);
  return { ...floor, buildingId: null };
}

export function assertProjectRoomSnapshot(
  room: unknown
): asserts room is ProjectRoomSnapshot {
  if (!isPlainObject(room) || Object.keys(room).length !== 5) {
    throw new Error("Project-room snapshot is invalid.");
  }
  assertNormalizedNonEmptyString(room.id, "room.id");
  assertNormalizedNonEmptyString(room.projectId, "room.projectId");
  if (room.floorId !== null) {
    assertNormalizedNonEmptyString(room.floorId, "room.floorId");
  }
  assertNormalizedNonEmptyString(room.roomNumber, "room.roomNumber");
  assertNormalizedNonEmptyString(room.roomName, "room.roomName");
}

function assertProjectBuildingStructureProjectCommand(
  command: SerializedProjectCommand<unknown>,
  expectedType:
    | typeof projectBuildingInsertCommandType
    | typeof projectBuildingDeleteCommandType
) {
  if (
    command.schemaVersion !== projectLocationStructureCommandSchemaVersion ||
    command.type !== expectedType ||
    !isPlainObject(command.payload) ||
    Object.keys(command.payload).length !== 1
  ) {
    throw new Error("Unsupported project-building structure command.");
  }
  assertProjectBuildingSnapshot(command.payload.building);
}

function assertProjectFloorStructureProjectCommand(
  command: SerializedProjectCommand<unknown>,
  expectedType:
    | typeof projectFloorInsertCommandType
    | typeof projectFloorDeleteCommandType
) {
  if (
    command.type !== expectedType ||
    !isPlainObject(command.payload) ||
    Object.keys(command.payload).length !== 1
  ) {
    throw new Error("Unsupported project-floor structure command.");
  }
  if (command.schemaVersion === legacyProjectFloorCommandSchemaVersion) {
    assertLegacyProjectFloorSnapshot(command.payload.floor);
    return;
  }
  if (command.schemaVersion !== projectFloorCommandSchemaVersion) {
    throw new Error("Unsupported project-floor structure command.");
  }
  assertProjectFloorSnapshot(command.payload.floor);
}

function assertProjectRoomStructureProjectCommand(
  command: SerializedProjectCommand<unknown>,
  expectedType:
    | typeof projectRoomInsertCommandType
    | typeof projectRoomDeleteCommandType
) {
  if (
    command.schemaVersion !== projectLocationStructureCommandSchemaVersion ||
    command.type !== expectedType ||
    !isPlainObject(command.payload) ||
    Object.keys(command.payload).length !== 1
  ) {
    throw new Error("Unsupported project-room structure command.");
  }
  assertProjectRoomSnapshot(command.payload.room);
}

function assertSortOrder(value: unknown, field: string) {
  if (
    typeof value !== "number" ||
    !Number.isSafeInteger(value) ||
    value < 0
  ) {
    throw new Error(`${field} must be a non-negative integer.`);
  }
}

function assertNormalizedNonEmptyString(
  value: unknown,
  field: string
): asserts value is string {
  if (
    typeof value !== "string" ||
    !value ||
    value !== value.trim()
  ) {
    throw new Error(`${field} must be a normalized non-empty string.`);
  }
}

function isPlainObject(value: unknown): value is Record<string, unknown> {
  return value !== null && typeof value === "object" && !Array.isArray(value);
}

function sameSnapshot(left: object, right: object) {
  return Object.entries(left).every(
    ([key, value]) => (right as Record<string, unknown>)[key] === value
  );
}