import {
  circuitGroupCategoryNumbers,
  type CircuitGroupCategory,
} from "../../shared/constants/circuit-group.js";

export type GroupedEquipmentIdentifierKind =
  | "group_upstream_protection"
  | "group_rcd"
  | "circuit";

export interface ParsedGroupedEquipmentIdentifier {
  category: CircuitGroupCategory;
  groupNumber: number;
  kind: GroupedEquipmentIdentifierKind;
  circuitNumber: number | null;
}

const categoryByNumber: Record<string, CircuitGroupCategory> = {
  "1": "lighting",
  "2": "single_phase",
  "3": "three_phase",
};

function requirePositiveInteger(value: number, fieldName: string): void {
  if (!Number.isInteger(value) || value < 1) {
    throw new RangeError(`${fieldName} must be a positive integer`);
  }
}

function getGroupStem(
  category: CircuitGroupCategory,
  functionLetter: "F" | "Q",
  groupNumber: number
): string {
  requirePositiveInteger(groupNumber, "groupNumber");
  return `-${circuitGroupCategoryNumbers[category]}${functionLetter}${groupNumber}`;
}

export function formatCircuitGroupPrefix(
  category: CircuitGroupCategory,
  groupNumber: number
) {
  return `${getGroupStem(category, "F", groupNumber)}.`;
}

export function formatGroupUpstreamProtectionIdentifier(
  category: CircuitGroupCategory,
  groupNumber: number
): string {
  return `${getGroupStem(category, "F", groupNumber)}.0`;
}

export function formatGroupRcdIdentifier(
  category: CircuitGroupCategory,
  groupNumber: number
): string {
  return `${getGroupStem(category, "Q", groupNumber)}.0`;
}

export function formatGroupedCircuitIdentifier(
  category: CircuitGroupCategory,
  groupNumber: number,
  circuitNumber: number
): string {
  requirePositiveInteger(circuitNumber, "circuitNumber");
  return `${getGroupStem(category, "F", groupNumber)}.${circuitNumber}`;
}

export function parseGroupedEquipmentIdentifier(
  equipmentIdentifier: string
): ParsedGroupedEquipmentIdentifier | null {
  const match = /^-(1|2|3)(F|Q)([1-9]\d*)\.(0|[1-9]\d*)$/.exec(
    equipmentIdentifier
  );
  if (!match) {
    return null;
  }

  const [, categoryNumber, functionLetter, groupNumberValue, suffixValue] =
    match;
  const category = categoryByNumber[categoryNumber];
  const groupNumber = Number(groupNumberValue);
  const suffix = Number(suffixValue);

  if (functionLetter === "Q") {
    return suffix === 0
      ? {
          category,
          groupNumber,
          kind: "group_rcd",
          circuitNumber: null,
        }
      : null;
  }

  if (suffix === 0) {
    return {
      category,
      groupNumber,
      kind: "group_upstream_protection",
      circuitNumber: null,
    };
  }

  return {
    category,
    groupNumber,
    kind: "circuit",
    circuitNumber: suffix,
  };
}

export function getNextGroupedCircuitNumber(
  category: CircuitGroupCategory,
  groupNumber: number,
  equipmentIdentifiers: Iterable<string>
): number {
  requirePositiveInteger(groupNumber, "groupNumber");
  let highestCircuitNumber = 0;

  for (const equipmentIdentifier of equipmentIdentifiers) {
    const parsed = parseGroupedEquipmentIdentifier(equipmentIdentifier);
    if (
      parsed?.kind === "circuit" &&
      parsed.category === category &&
      parsed.groupNumber === groupNumber &&
      parsed.circuitNumber !== null
    ) {
      highestCircuitNumber = Math.max(
        highestCircuitNumber,
        parsed.circuitNumber
      );
    }
  }

  return highestCircuitNumber + 1;
}

export function getNextGroupedCircuitIdentifier(
  category: CircuitGroupCategory,
  groupNumber: number,
  equipmentIdentifiers: Iterable<string>
): string {
  return formatGroupedCircuitIdentifier(
    category,
    groupNumber,
    getNextGroupedCircuitNumber(
      category,
      groupNumber,
      equipmentIdentifiers
    )
  );
}

export function getNextCircuitGroupNumber(
  category: CircuitGroupCategory,
  groups: Iterable<{
    category: CircuitGroupCategory;
    groupNumber: number;
  }>
): number {
  let highestGroupNumber = 0;

  for (const group of groups) {
    if (group.category === category) {
      requirePositiveInteger(group.groupNumber, "groupNumber");
      highestGroupNumber = Math.max(highestGroupNumber, group.groupNumber);
    }
  }

  return highestGroupNumber + 1;
}