import {
  distributionBoardInfoFieldMaxLengths,
  distributionBoardInfoFields,
  distributionBoardSupplyTypes,
  type DistributionBoardInfoField,
  type DistributionBoardSupplyType,
} from "../../shared/constants/distribution-board.js";
import type { SerializedProjectCommand } from "./project-command.model.js";

export const distributionBoardUpdateCommandType =
  "distribution-board.update" as const;
// Version 2 adds logical feeding references. Version-1 commands remain
// executable and can only change the fields they originally knew.
export const distributionBoardUpdateCommandSchemaVersion = 2 as const;
const legacyDistributionBoardUpdateCommandSchemaVersion = 1 as const;

export interface DistributionBoardUpdateValues
  extends Record<DistributionBoardInfoField, string | null> {
  floorId: string | null;
  supplyType: DistributionBoardSupplyType | null;
  simultaneityFactor: number;
  feedingDistributionBoardId: string | null;
  feedingCircuitId: string | null;
}

export type DistributionBoardUpdateField =
  keyof DistributionBoardUpdateValues;
export type DistributionBoardUpdatePatch =
  Partial<DistributionBoardUpdateValues>;

export interface DistributionBoardUpdateFieldChange<
  TField extends DistributionBoardUpdateField =
    DistributionBoardUpdateField,
> {
  field: TField;
  value: DistributionBoardUpdateValues[TField];
}

export interface DistributionBoardUpdateCommandPayload {
  distributionBoardId: string;
  changes: DistributionBoardUpdateFieldChange[];
}

export interface DistributionBoardUpdateProjectCommand
  extends SerializedProjectCommand<DistributionBoardUpdateCommandPayload> {
  schemaVersion:
    | typeof legacyDistributionBoardUpdateCommandSchemaVersion
    | typeof distributionBoardUpdateCommandSchemaVersion;
  type: typeof distributionBoardUpdateCommandType;
}

export function createDistributionBoardUpdateProjectCommand(
  distributionBoardId: string,
  patch: DistributionBoardUpdatePatch,
  schemaVersion: DistributionBoardUpdateProjectCommand["schemaVersion"] =
    distributionBoardUpdateCommandSchemaVersion
): DistributionBoardUpdateProjectCommand {
  const command: DistributionBoardUpdateProjectCommand = {
    schemaVersion,
    type: distributionBoardUpdateCommandType,
    payload: {
      distributionBoardId,
      changes: Object.entries(patch).map(([field, value]) => ({
        field: field as DistributionBoardUpdateField,
        value,
      })) as DistributionBoardUpdateFieldChange[],
    },
  };
  assertDistributionBoardUpdateProjectCommand(command);
  return command;
}

export function assertDistributionBoardUpdateProjectCommand(
  command: SerializedProjectCommand<unknown>
): asserts command is DistributionBoardUpdateProjectCommand {
  if (
    (command.schemaVersion !== legacyDistributionBoardUpdateCommandSchemaVersion &&
      command.schemaVersion !== distributionBoardUpdateCommandSchemaVersion) ||
    command.type !== distributionBoardUpdateCommandType ||
    !isPlainObject(command.payload)
  ) {
    throw new Error("Unsupported distribution-board update command.");
  }
  const { distributionBoardId, changes } = command.payload;
  if (
    typeof distributionBoardId !== "string" ||
    !distributionBoardId.trim() ||
    !Array.isArray(changes) ||
    changes.length === 0
  ) {
    throw new Error(
      "Distribution-board update command requires an id and changes."
    );
  }
  const seen = new Set<string>();
  for (const change of changes) {
    if (
      !isPlainObject(change) ||
      typeof change.field !== "string" ||
      (change.field !== "floorId" &&
        change.field !== "supplyType" &&
        change.field !== "simultaneityFactor" &&
        change.field !== "feedingDistributionBoardId" &&
        change.field !== "feedingCircuitId" &&
        !isInfoField(change.field)) ||
      (command.schemaVersion === legacyDistributionBoardUpdateCommandSchemaVersion &&
        (change.field === "feedingDistributionBoardId" ||
          change.field === "feedingCircuitId")) ||
      seen.has(change.field)
    ) {
      throw new Error(
        "Distribution-board update contains an invalid or duplicate field."
      );
    }
    if (isInfoField(change.field)) {
      assertInfoFieldValue(change.field, change.value);
    } else if (change.field === "floorId") {
      if (
        change.value !== null &&
        (typeof change.value !== "string" ||
          !change.value.trim() ||
          change.value !== change.value.trim())
      ) {
        throw new Error("floorId must be a non-empty string or null.");
      }
    } else if (change.field === "supplyType") {
      if (
        change.value !== null &&
        !distributionBoardSupplyTypes.includes(
          change.value as DistributionBoardSupplyType
        )
      ) {
        throw new Error("supplyType is invalid.");
      }
    } else if (
      change.field === "feedingDistributionBoardId" ||
      change.field === "feedingCircuitId"
    ) {
      if (
        change.value !== null &&
        (typeof change.value !== "string" || !change.value.trim())
      ) {
        throw new Error(`${change.field} must be a non-empty string or null.`);
      }
    } else if (
      typeof change.value !== "number" ||
      !Number.isFinite(change.value) ||
      change.value < 0 ||
      change.value > 1
    ) {
      throw new Error(
        "simultaneityFactor must be between zero and one."
      );
    }
    seen.add(change.field);
  }
}

function isInfoField(field: string): field is DistributionBoardInfoField {
  return (distributionBoardInfoFields as readonly string[]).includes(field);
}

function assertInfoFieldValue(
  field: DistributionBoardInfoField,
  value: unknown
) {
  if (value === null) {
    return;
  }
  if (
    typeof value !== "string" ||
    !value.trim() ||
    value !== value.trim() ||
    value.length > distributionBoardInfoFieldMaxLengths[field]
  ) {
    throw new Error(
      `${field} must be a trimmed, non-empty string of at most ${distributionBoardInfoFieldMaxLengths[field]} characters or null.`
    );
  }
}

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