import {
  assertCircuitDeviceRowUpdateProjectCommand,
  circuitDeviceRowUpdateCommandSchemaVersion,
  circuitDeviceRowUpdateCommandType,
  type CircuitDeviceRowUpdateField,
  type CircuitDeviceRowUpdateValues,
} from "./circuit-device-row-project-command.model.js";
import type { SerializedProjectCommand } from "./project-command.model.js";

export const projectDeviceRowSyncCommandType =
  "project-device.sync-rows" as const;
export const projectDeviceRowSyncCommandSchemaVersion = 1 as const;

export const projectDeviceSyncRowSnapshotFields = [
  "linkedProjectDeviceId",
  "name",
  "displayName",
  "phaseType",
  "connectionKind",
  "costGroup",
  "category",
  "quantity",
  "powerPerUnit",
  "simultaneityFactor",
  "cosPhi",
  "remark",
  "overriddenFields",
] as const satisfies readonly CircuitDeviceRowUpdateField[];

export type ProjectDeviceSyncRowSnapshot = Pick<
  CircuitDeviceRowUpdateValues,
  (typeof projectDeviceSyncRowSnapshotFields)[number]
>;

export type ProjectDeviceRowSyncOperation =
  | "synchronize"
  | "disconnect"
  | "reconnect";

export interface ProjectDeviceRowSyncAssignment {
  rowId: string;
  expected: ProjectDeviceSyncRowSnapshot;
  target: ProjectDeviceSyncRowSnapshot;
}

export interface ProjectDeviceRowSyncCommandPayload {
  projectDeviceId: string;
  operation: ProjectDeviceRowSyncOperation;
  rows: ProjectDeviceRowSyncAssignment[];
}

export interface ProjectDeviceRowSyncProjectCommand
  extends SerializedProjectCommand<ProjectDeviceRowSyncCommandPayload> {
  schemaVersion: typeof projectDeviceRowSyncCommandSchemaVersion;
  type: typeof projectDeviceRowSyncCommandType;
}

export function createProjectDeviceRowSyncProjectCommand(
  projectDeviceId: string,
  operation: ProjectDeviceRowSyncOperation,
  rows: ProjectDeviceRowSyncAssignment[]
): ProjectDeviceRowSyncProjectCommand {
  const command: ProjectDeviceRowSyncProjectCommand = {
    schemaVersion: projectDeviceRowSyncCommandSchemaVersion,
    type: projectDeviceRowSyncCommandType,
    payload: { projectDeviceId, operation, rows },
  };
  assertProjectDeviceRowSyncProjectCommand(command);
  return command;
}

export function assertProjectDeviceRowSyncProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is ProjectDeviceRowSyncProjectCommand {
  if (
    command.schemaVersion !== projectDeviceRowSyncCommandSchemaVersion ||
    command.type !== projectDeviceRowSyncCommandType
  ) {
    throw new Error("Unsupported project-device row sync command.");
  }
  if (!isPlainObject(command.payload)) {
    throw new Error(
      "Project-device row sync payload must be an object."
    );
  }
  const { projectDeviceId, operation, rows } = command.payload;
  assertNonEmptyString(projectDeviceId, "projectDeviceId");
  if (
    operation !== "synchronize" &&
    operation !== "disconnect" &&
    operation !== "reconnect"
  ) {
    throw new Error(
      "Project-device row sync operation is invalid."
    );
  }
  if (!Array.isArray(rows) || rows.length === 0) {
    throw new Error(
      "Project-device row sync command requires at least one row."
    );
  }

  const rowIds = new Set<string>();
  for (const row of rows) {
    if (!isPlainObject(row)) {
      throw new Error(
        "Project-device row sync command contains an invalid row."
      );
    }
    assertNonEmptyString(row.rowId, "rowId");
    if (rowIds.has(row.rowId)) {
      throw new Error(
        "Project-device row sync command contains duplicate row ids."
      );
    }
    assertProjectDeviceSyncRowSnapshot(row.expected);
    assertProjectDeviceSyncRowSnapshot(row.target);
    const expected =
      row.expected as ProjectDeviceSyncRowSnapshot;
    const target = row.target as ProjectDeviceSyncRowSnapshot;
    if (snapshotsEqual(expected, target)) {
      throw new Error(
        "Project-device row sync command contains a no-op row."
      );
    }
    assertOperationTransition(
      operation,
      projectDeviceId,
      expected,
      target
    );
    rowIds.add(row.rowId);
  }
}

export function invertProjectDeviceRowSyncOperation(
  operation: ProjectDeviceRowSyncOperation
): ProjectDeviceRowSyncOperation {
  if (operation === "disconnect") {
    return "reconnect";
  }
  if (operation === "reconnect") {
    return "disconnect";
  }
  return "synchronize";
}

function assertProjectDeviceSyncRowSnapshot(snapshot: unknown) {
  if (!isPlainObject(snapshot)) {
    throw new Error(
      "Project-device sync row snapshot must be an object."
    );
  }
  const snapshotKeys = Object.keys(snapshot);
  if (
    snapshotKeys.length !== projectDeviceSyncRowSnapshotFields.length ||
    projectDeviceSyncRowSnapshotFields.some(
      (field) =>
        !Object.prototype.hasOwnProperty.call(snapshot, field)
    )
  ) {
    throw new Error(
      "Project-device sync row snapshot must contain every sync field."
    );
  }
  assertCircuitDeviceRowUpdateProjectCommand({
    schemaVersion: circuitDeviceRowUpdateCommandSchemaVersion,
    type: circuitDeviceRowUpdateCommandType,
    payload: {
      rowId: "__sync_snapshot_validation__",
      changes: projectDeviceSyncRowSnapshotFields.map((field) => ({
        field,
        value: snapshot[field],
      })),
    },
  });
}

function assertOperationTransition(
  operation: ProjectDeviceRowSyncOperation,
  projectDeviceId: string,
  expected: ProjectDeviceSyncRowSnapshot,
  target: ProjectDeviceSyncRowSnapshot
) {
  if (operation === "synchronize") {
    if (
      expected.linkedProjectDeviceId !== projectDeviceId ||
      target.linkedProjectDeviceId !== projectDeviceId
    ) {
      throw new Error(
        "Synchronized rows must remain linked to the selected project device."
      );
    }
    return;
  }

  const expectedLink =
    operation === "disconnect" ? projectDeviceId : null;
  const targetLink =
    operation === "disconnect" ? null : projectDeviceId;
  if (
    expected.linkedProjectDeviceId !== expectedLink ||
    target.linkedProjectDeviceId !== targetLink
  ) {
    throw new Error(
      "Project-device link transition does not match the operation."
    );
  }
  if (!snapshotsEqualWithoutLink(expected, target)) {
    throw new Error(
      "Disconnect and reconnect must not change local row values."
    );
  }
}

function snapshotsEqual(
  left: ProjectDeviceSyncRowSnapshot,
  right: ProjectDeviceSyncRowSnapshot
) {
  return projectDeviceSyncRowSnapshotFields.every(
    (field) => left[field] === right[field]
  );
}

function snapshotsEqualWithoutLink(
  left: ProjectDeviceSyncRowSnapshot,
  right: ProjectDeviceSyncRowSnapshot
) {
  return projectDeviceSyncRowSnapshotFields
    .filter((field) => field !== "linkedProjectDeviceId")
    .every((field) => left[field] === right[field]);
}

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

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