/**
 * @param {string} value
 * @returns {RegExp}
 * */

/**
 * @param {RegExp | string } re
 * @returns {string}
 */
function source(re) {
  if (!re) return null;
  if (typeof re === "string") return re;

  return re.source;
}

/**
 * @param {...(RegExp | string) } args
 * @returns {string}
 */
function concat(...args) {
  const joined = args.map((x) => source(x)).join("");
  return joined;
}

/*
Language: Fortran
Author: Anthony Scemama <scemama@irsamc.ups-tlse.fr>
Website: https://en.wikipedia.org/wiki/Fortran
Category: scientific
*/

/** @type LanguageFn */
function fortran(hljs) {
  const PARAMS = {
    className: 'params',
    begin: '\\(',
    end: '\\)'
  };

  const COMMENT = {
    variants: [
      hljs.COMMENT('!', '$', {
        relevance: 0
      }),
      // allow FORTRAN 77 style comments
      hljs.COMMENT('^C[ ]', '$', {
        relevance: 0
      }),
      hljs.COMMENT('^C$', '$', {
        relevance: 0
      })
    ]
  };

  // regex in both fortran and irpf90 should match
  const OPTIONAL_NUMBER_SUFFIX = /(_[a-z_\d]+)?/;
  const OPTIONAL_NUMBER_EXP = /([de][+-]?\d+)?/;
  const NUMBER = {
    className: 'number',
    variants: [
      {
        begin: concat(/\b\d+/, /\.(\d*)/, OPTIONAL_NUMBER_EXP, OPTIONAL_NUMBER_SUFFIX)
      },
      {
        begin: concat(/\b\d+/, OPTIONAL_NUMBER_EXP, OPTIONAL_NUMBER_SUFFIX)
      },
      {
        begin: concat(/\.\d+/, OPTIONAL_NUMBER_EXP, OPTIONAL_NUMBER_SUFFIX)
      }
    ],
    relevance: 0
  };

  const FUNCTION_DEF = {
    className: 'function',
    beginKeywords: 'subroutine function program',
    illegal: '[${=\\n]',
    contains: [
      hljs.UNDERSCORE_TITLE_MODE,
      PARAMS
    ]
  };

  const STRING = {
    className: 'string',
    relevance: 0,
    variants: [
      hljs.APOS_STRING_MODE,
      hljs.QUOTE_STRING_MODE
    ]
  };

  const KEYWORDS = {
    literal: '.False. .True.',
    keyword: 'kind do concurrent local shared while private call intrinsic where elsewhere ' +
      'type endtype endmodule endselect endinterface end enddo endif if forall endforall only contains default return stop then block endblock endassociate ' +
      'public subroutine|10 function program .and. .or. .not. .le. .eq. .ge. .gt. .lt. ' +
      'goto save else use module select case ' +
      'access blank direct exist file fmt form formatted iostat name named nextrec number opened rec recl sequential status unformatted unit ' +
      'continue format pause cycle exit ' +
      'c_null_char c_alert c_backspace c_form_feed flush wait decimal round iomsg ' +
      'synchronous nopass non_overridable pass protected volatile abstract extends import ' +
      'non_intrinsic value deferred generic final enumerator class associate bind enum ' +
      'c_int c_short c_long c_long_long c_signed_char c_size_t c_int8_t c_int16_t c_int32_t c_int64_t c_int_least8_t c_int_least16_t ' +
      'c_int_least32_t c_int_least64_t c_int_fast8_t c_int_fast16_t c_int_fast32_t c_int_fast64_t c_intmax_t C_intptr_t c_float c_double ' +
      'c_long_double c_float_complex c_double_complex c_long_double_complex c_bool c_char c_null_ptr c_null_funptr ' +
      'c_new_line c_carriage_return c_horizontal_tab c_vertical_tab iso_c_binding c_loc c_funloc c_associated  c_f_pointer ' +
      'c_ptr c_funptr iso_fortran_env character_storage_size error_unit file_storage_size input_unit iostat_end iostat_eor ' +
      'numeric_storage_size output_unit c_f_procpointer ieee_arithmetic ieee_support_underflow_control ' +
      'ieee_get_underflow_mode ieee_set_underflow_mode newunit contiguous recursive ' +
      'pad position action delim readwrite eor advance nml interface procedure namelist include sequence elemental pure impure ' +
      'integer real character complex logical codimension dimension allocatable|10 parameter ' +
      'external implicit|10 none double precision assign intent optional pointer ' +
      'target in out common equivalence data',
    built_in: 'alog alog10 amax0 amax1 amin0 amin1 amod cabs ccos cexp clog csin csqrt dabs dacos dasin datan datan2 dcos dcosh ddim dexp dint ' +
      'dlog dlog10 dmax1 dmin1 dmod dnint dsign dsin dsinh dsqrt dtan dtanh float iabs idim idint idnint ifix isign max0 max1 min0 min1 sngl ' +
      'algama cdabs cdcos cdexp cdlog cdsin cdsqrt cqabs cqcos cqexp cqlog cqsin cqsqrt dcmplx dconjg derf derfc dfloat dgamma dimag dlgama ' +
      'iqint qabs qacos qasin qatan qatan2 qcmplx qconjg qcos qcosh qdim qerf qerfc qexp qgamma qimag qlgama qlog qlog10 qmax1 qmin1 qmod ' +
      'qnint qsign qsin qsinh qsqrt qtan qtanh abs acos aimag aint anint asin atan atan2 char cmplx conjg cos cosh exp ichar index int log ' +
      'log10 max min nint sign sin sinh sqrt tan tanh print write dim lge lgt lle llt mod nullify allocate deallocate ' +
      'adjustl adjustr all allocated any associated bit_size btest ceiling count cshift date_and_time digits dot_product ' +
      'eoshift epsilon exponent floor fraction huge iand ibclr ibits ibset ieor ior ishft ishftc lbound len_trim matmul ' +
      'maxexponent maxloc maxval merge minexponent minloc minval modulo mvbits nearest pack present product ' +
      'radix random_number random_seed range repeat reshape rrspacing scale scan selected_int_kind selected_real_kind ' +
      'set_exponent shape size spacing spread sum system_clock tiny transpose trim ubound unpack verify achar iachar transfer ' +
      'dble entry dprod cpu_time command_argument_count get_command get_command_argument get_environment_variable is_iostat_end ' +
      'ieee_arithmetic ieee_support_underflow_control ieee_get_underflow_mode ieee_set_underflow_mode ' +
      'is_iostat_eor move_alloc new_line selected_char_kind same_type_as extends_type_of ' +
      'acosh asinh atanh bessel_j0 bessel_j1 bessel_jn bessel_y0 bessel_y1 bessel_yn erf erfc erfc_scaled gamma log_gamma hypot norm2 ' +
      'atomic_define atomic_ref execute_command_line leadz trailz storage_size merge_bits ' +
      'bge bgt ble blt dshiftl dshiftr findloc iall iany iparity image_index lcobound ucobound maskl maskr ' +
      'num_images parity popcnt poppar shifta shiftl shiftr this_image sync change team co_broadcast co_max co_min co_sum co_reduce'
  };
  return {
    name: 'Fortran',
    case_insensitive: true,
    aliases: [
      'f90',
      'f95'
    ],
    keywords: KEYWORDS,
    illegal: /\/\*/,
    contains: [
      STRING,
      FUNCTION_DEF,
      // allow `C = value` for assignments so they aren't misdetected
      // as Fortran 77 style comments
      {
        begin: /^C\s*=(?!=)/,
        relevance: 0
      },
      COMMENT,
      NUMBER
    ]
  };
}

module.exports = fortran;