import crypto from "node:crypto";
import {
  distributionBoardSupplyTypes,
  type DistributionBoardSupplyType,
} from "../../shared/constants/distribution-board.js";
import type { SerializedProjectCommand } from "./project-command.model.js";

export const distributionBoardInsertCommandType =
  "distribution-board.insert" as const;
export const distributionBoardDeleteCommandType =
  "distribution-board.delete" as const;
export const legacyDistributionBoardStructureCommandSchemaVersion = 1 as const;
export const distributionBoardStructureCommandSchemaVersion = 2 as const;

export const defaultCircuitSectionDefinitions = [
  {
    key: "lighting",
    displayName: "Lighting",
    prefix: "-1F",
    sortOrder: 10,
  },
  {
    key: "single_phase",
    displayName: "Single-phase circuits",
    prefix: "-2F",
    sortOrder: 20,
  },
  {
    key: "three_phase",
    displayName: "Three-phase circuits",
    prefix: "-3F",
    sortOrder: 30,
  },
  {
    key: "unassigned",
    displayName: "Unassigned",
    prefix: "-UF",
    sortOrder: 90,
  },
] as const;

interface LegacyDistributionBoardStructureSnapshot {
  distributionBoard: {
    id: string;
    projectId: string;
    name: string;
  };
  circuitList: DistributionBoardStructureSnapshot["circuitList"];
  sections: DistributionBoardStructureSnapshot["sections"];
}

export interface DistributionBoardStructureSnapshot {
  distributionBoard: {
    id: string;
    projectId: string;
    name: string;
    floorId: string | null;
    supplyType: DistributionBoardSupplyType | null;
  };
  circuitList: {
    id: string;
    projectId: string;
    distributionBoardId: string;
    name: string;
  };
  sections: Array<{
    id: string;
    circuitListId: string;
    key: string;
    displayName: string;
    prefix: string;
    sortOrder: number;
  }>;
}

interface DistributionBoardStructureCommandPayload<
  TStructure = DistributionBoardStructureSnapshot,
> {
  structure: TStructure;
}

interface CurrentDistributionBoardStructureProjectCommand
  extends SerializedProjectCommand<DistributionBoardStructureCommandPayload> {
  schemaVersion: typeof distributionBoardStructureCommandSchemaVersion;
  type:
    | typeof distributionBoardInsertCommandType
    | typeof distributionBoardDeleteCommandType;
}

interface LegacyDistributionBoardStructureProjectCommand
  extends SerializedProjectCommand<
    DistributionBoardStructureCommandPayload<LegacyDistributionBoardStructureSnapshot>
  > {
  schemaVersion: typeof legacyDistributionBoardStructureCommandSchemaVersion;
  type:
    | typeof distributionBoardInsertCommandType
    | typeof distributionBoardDeleteCommandType;
}

export interface DistributionBoardInsertProjectCommand
  extends CurrentDistributionBoardStructureProjectCommand {
  type: typeof distributionBoardInsertCommandType;
}

export interface DistributionBoardDeleteProjectCommand
  extends CurrentDistributionBoardStructureProjectCommand {
  type: typeof distributionBoardDeleteCommandType;
}

export type DistributionBoardStructureProjectCommand =
  | DistributionBoardInsertProjectCommand
  | DistributionBoardDeleteProjectCommand
  | LegacyDistributionBoardStructureProjectCommand;

export function createDistributionBoardStructureSnapshot(
  projectId: string,
  name: string,
  input: {
    floorId?: string | null;
    supplyType?: DistributionBoardSupplyType | null;
  } = {}
): DistributionBoardStructureSnapshot {
  const normalizedName = name.trim();
  assertNonEmptyString(projectId, "projectId");
  assertNonEmptyString(normalizedName, "name");
  const structureId = crypto.randomUUID();
  const structure: DistributionBoardStructureSnapshot = {
    distributionBoard: {
      id: structureId,
      projectId,
      name: normalizedName,
      floorId: input.floorId ?? null,
      supplyType: input.supplyType ?? null,
    },
    circuitList: {
      id: structureId,
      projectId,
      distributionBoardId: structureId,
      name: `${normalizedName} Stromkreisliste`,
    },
    sections: defaultCircuitSectionDefinitions.map((section) => ({
      id: crypto.randomUUID(),
      circuitListId: structureId,
      ...section,
    })),
  };
  assertDistributionBoardStructureSnapshot(structure);
  return structure;
}

export function createDistributionBoardInsertProjectCommand(
  structure: DistributionBoardStructureSnapshot
): DistributionBoardInsertProjectCommand {
  const command: DistributionBoardInsertProjectCommand = {
    schemaVersion: distributionBoardStructureCommandSchemaVersion,
    type: distributionBoardInsertCommandType,
    payload: { structure },
  };
  assertDistributionBoardInsertProjectCommand(command);
  return command;
}

export function createDistributionBoardDeleteProjectCommand(
  structure: DistributionBoardStructureSnapshot
): DistributionBoardDeleteProjectCommand {
  const command: DistributionBoardDeleteProjectCommand = {
    schemaVersion: distributionBoardStructureCommandSchemaVersion,
    type: distributionBoardDeleteCommandType,
    payload: { structure },
  };
  assertDistributionBoardDeleteProjectCommand(command);
  return command;
}

export function assertDistributionBoardInsertProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is DistributionBoardStructureProjectCommand {
  assertDistributionBoardStructureProjectCommand(
    command,
    distributionBoardInsertCommandType
  );
}

export function assertDistributionBoardDeleteProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is DistributionBoardStructureProjectCommand {
  assertDistributionBoardStructureProjectCommand(
    command,
    distributionBoardDeleteCommandType
  );
}

export function normalizeDistributionBoardStructureProjectCommand(
  command: DistributionBoardStructureProjectCommand
): DistributionBoardInsertProjectCommand | DistributionBoardDeleteProjectCommand {
  if (
    command.schemaVersion ===
    legacyDistributionBoardStructureCommandSchemaVersion
  ) {
    const structure: DistributionBoardStructureSnapshot = {
      ...command.payload.structure,
      distributionBoard: {
        ...command.payload.structure.distributionBoard,
        floorId: null,
        supplyType: null,
      },
    };
    return command.type === distributionBoardInsertCommandType
      ? createDistributionBoardInsertProjectCommand(structure)
      : createDistributionBoardDeleteProjectCommand(structure);
  }
  return command as
    | DistributionBoardInsertProjectCommand
    | DistributionBoardDeleteProjectCommand;
}

export function assertDistributionBoardStructureSnapshot(
  structure: unknown
): asserts structure is DistributionBoardStructureSnapshot {
  assertDistributionBoardStructureSnapshotVersion(structure, false);
}

function assertDistributionBoardStructureProjectCommand(
  command: SerializedProjectCommand<unknown>,
  expectedType:
    | typeof distributionBoardInsertCommandType
    | typeof distributionBoardDeleteCommandType
) {
  if (
    command.type !== expectedType ||
    !isPlainObject(command.payload) ||
    Object.keys(command.payload).length !== 1
  ) {
    throw new Error("Unsupported distribution-board structure command.");
  }
  if (
    command.schemaVersion ===
    legacyDistributionBoardStructureCommandSchemaVersion
  ) {
    assertDistributionBoardStructureSnapshotVersion(
      command.payload.structure,
      true
    );
    return;
  }
  if (
    command.schemaVersion !== distributionBoardStructureCommandSchemaVersion
  ) {
    throw new Error("Unsupported distribution-board structure command.");
  }
  assertDistributionBoardStructureSnapshotVersion(
    command.payload.structure,
    false
  );
}

function assertDistributionBoardStructureSnapshotVersion(
  structure: unknown,
  legacy: boolean
) {
  if (!isPlainObject(structure) || Object.keys(structure).length !== 3) {
    throw new Error("Distribution-board structure is invalid.");
  }
  const { distributionBoard, circuitList, sections } = structure;
  if (
    !isPlainObject(distributionBoard) ||
    Object.keys(distributionBoard).length !== (legacy ? 3 : 5) ||
    !isPlainObject(circuitList) ||
    Object.keys(circuitList).length !== 4 ||
    !Array.isArray(sections) ||
    sections.length !== defaultCircuitSectionDefinitions.length
  ) {
    throw new Error("Distribution-board structure is incomplete.");
  }
  for (const field of ["id", "projectId", "name"] as const) {
    assertNonEmptyString(
      distributionBoard[field],
      `distributionBoard.${field}`
    );
  }
  if (!legacy) {
    assertNullableId(distributionBoard.floorId, "distributionBoard.floorId");
    assertNullableSupplyType(distributionBoard.supplyType);
  }
  for (const [field, value] of Object.entries(circuitList)) {
    assertNonEmptyString(value, `circuitList.${field}`);
  }
  if (
    circuitList.projectId !== distributionBoard.projectId ||
    circuitList.distributionBoardId !== distributionBoard.id ||
    circuitList.name !== `${distributionBoard.name} Stromkreisliste`
  ) {
    throw new Error("Distribution board and circuit list are inconsistent.");
  }

  const sectionIds = new Set<string>();
  for (let index = 0; index < sections.length; index += 1) {
    const section = sections[index];
    const expected = defaultCircuitSectionDefinitions[index];
    if (!isPlainObject(section) || Object.keys(section).length !== 6) {
      throw new Error("Default circuit section is invalid.");
    }
    assertNonEmptyString(section.id, "section.id");
    if (sectionIds.has(section.id)) {
      throw new Error("Default circuit-section ids must be unique.");
    }
    sectionIds.add(section.id);
    if (
      section.circuitListId !== circuitList.id ||
      section.key !== expected.key ||
      section.displayName !== expected.displayName ||
      section.prefix !== expected.prefix ||
      section.sortOrder !== expected.sortOrder
    ) {
      throw new Error(
        "Distribution-board structure has invalid default sections."
      );
    }
  }
}

function assertNullableId(value: unknown, field: string) {
  if (value !== null) {
    assertNonEmptyString(value, field);
  }
}

function assertNullableSupplyType(
  value: unknown
): asserts value is DistributionBoardSupplyType | null {
  if (
    value !== null &&
    !distributionBoardSupplyTypes.includes(
      value as DistributionBoardSupplyType
    )
  ) {
    throw new Error("distributionBoard.supplyType is invalid.");
  }
}

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);
}