vgrib2/src/templates/template-5.ts

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import { Buffer } from 'buffer/'

import { lookupTable51 } from '../tables/table-5'

/**
 * @description Returns a template generator for the given template number
 * @param template Template number
 * @returns Template generator
 */
export const getTemplate5 = (template: number) => {
  switch (template) {
    case 0:
      return template50
    default:
      throw new Error(`Template 5.${template} not defined`)
  }
}

/**
 * @description Returns a template map for the given template number
 * @param table Template number
 * @returns Template Map
 */
export const lookupTemplate5 = (template: number) => {
  switch (template) {
    case 0:
      return lookupTemplate50

    default:
      throw new Error(`Template 5.${template} lookup table not defined`)
  }
}

/**
 * Data Representation Template 5.0
 *
 * [Read more...](https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_temp5-0.shtml)
 */
const template50 = (section: Buffer) => {
  return {
    /** Reference value (R) (IEEE 32-bit floating-point value) */
    referenceValue: section.readFloatBE(11),
    /** Binary scale factor (E) */
    binaryScaleFactor: section.readInt16BE(15),
    /** Decimal scale factor (D) */
    decimalScaleFactor: section.readInt16BE(17),
    /** Number of bits used for each packed value for simple packing, or for each group reference value for complex packing or spatial differencing */
    numberOfBits: section.readUInt8(19),
    /** Type of original field values (see Code [Table 5.1](https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_table5-1.shtml)) */
    originalType: section.readUInt8(20)
  }
}

const lookupTemplate50 = (templateValues: ReturnType<typeof template50>) => {
  return {
    ...templateValues,
    /** Type of original field values */
    originalType: lookupTable51(templateValues.originalType)
  }
}