# Horizontal Domain Template Component 4.1 - Latitude/longitude regular grid

# Ni - number of points along a parallel
unsigned[4] Ni : dump; # Note: This is for a REGULAR GRID so Ni cannot be missing
alias numberOfPointsAlongAParallel=Ni;
alias Nx = Ni;
alias geography.Ni=Ni;

# Nj - number of points along a meridian
unsigned[4] Nj : dump;
alias numberOfPointsAlongAMeridian=Nj;
alias Ny = Nj ;
alias geography.Nj=Nj;

# Basic angle of the initial production domain
unsigned[4] basicAngleOfTheInitialProductionDomain = 0;
transient mBasicAngle=basicAngleOfTheInitialProductionDomain*oneMillionConstant;

transient angleMultiplier  = 1;
transient mAngleMultiplier = 1000000;
when (basicAngleOfTheInitialProductionDomain == 0) {
  set angleMultiplier  = 1;
  set mAngleMultiplier = 1000000;
} else {
  set angleMultiplier  = basicAngleOfTheInitialProductionDomain;
  set mAngleMultiplier = mBasicAngle;
}

# Subdivisions of basic angle used to define extreme longitudes and latitudes, and direction increments
unsigned[4] subdivisionsOfBasicAngle = missing() : can_be_missing;

transient angleDivisor = 1000000;
when (missing(subdivisionsOfBasicAngle) || subdivisionsOfBasicAngle == 0) {
  set angleDivisor  = 1000000;
} else {
  set angleDivisor  = subdivisionsOfBasicAngle;
}

# Note: Basic angle of the initial production domain and subdivisions of this basic angle are
# provided to manage cases where the recommended unit of 10^-6 degrees is not applicable
# to describe the extreme longitudes and latitudes, and direction increments.
# For these descriptors, the unit is equal to the ratio of the basic angle and the subdivisions number.
# For ordinary cases, zero and missing values should be coded, equivalent to respective values
# of 1 and 10^6 (10^-6 degrees unit)

# La1 - latitude of first grid point
signed[4] latitudeOfFirstGridPoint : edition_specific;
alias La1  = latitudeOfFirstGridPoint;

# Lo1 - longitude of first grid point
signed[4] longitudeOfFirstGridPoint ;
alias Lo1  = longitudeOfFirstGridPoint;

include "grib3/template.4.resolution_flags.def"

# La2 - latitude of last grid point
signed[4] latitudeOfLastGridPoint :  edition_specific;
alias La2 =  latitudeOfLastGridPoint;

# Lo2 - longitude of last grid point
signed[4] longitudeOfLastGridPoint :  edition_specific;
alias Lo2 =  longitudeOfLastGridPoint;

# Di - i direction increment
# Direction increments are unsigned and direction of increment is represented in the scanning mode
unsigned[4] iDirectionIncrement : can_be_missing,edition_specific;
alias Di =  iDirectionIncrement;
alias Dx =  iDirectionIncrement;

# Dj - j direction increment
# Direction increments are unsigned and direction of increment is represented in the scanning mode
unsigned[4] jDirectionIncrement : can_be_missing,edition_specific;
alias Dj =  jDirectionIncrement;
alias Dy =  jDirectionIncrement;

include "grib3/template.4.scanning_mode.def";


meta g2grid g2grid(
  latitudeOfFirstGridPoint,
  longitudeOfFirstGridPoint,
  latitudeOfLastGridPoint,
  longitudeOfLastGridPoint,
  iDirectionIncrement,
  jDirectionIncrement,
  basicAngleOfTheInitialProductionDomain,
  subdivisionsOfBasicAngle
  );

meta      geography.latitudeOfFirstGridPointInDegrees    g2latlon(g2grid,0) : dump;
meta      geography.longitudeOfFirstGridPointInDegrees   g2latlon(g2grid,1) : dump;
meta      geography.latitudeOfLastGridPointInDegrees     g2latlon(g2grid,2) : dump;
meta      geography.longitudeOfLastGridPointInDegrees    g2latlon(g2grid,3) : dump;

alias xFirst=longitudeOfFirstGridPointInDegrees;
alias yFirst=latitudeOfFirstGridPointInDegrees;
alias xLast=longitudeOfLastGridPointInDegrees;
alias yLast=latitudeOfLastGridPointInDegrees;

meta geography.iDirectionIncrementInDegrees    g2latlon(g2grid,4,
  iDirectionIncrementGiven) : can_be_missing,dump;

meta geography.jDirectionIncrementInDegrees    g2latlon(g2grid,5,
  jDirectionIncrementGiven) : can_be_missing,dump;

alias latitudeFirstInDegrees  = latitudeOfFirstGridPointInDegrees;
alias longitudeFirstInDegrees = longitudeOfFirstGridPointInDegrees;
alias latitudeLastInDegrees   = latitudeOfLastGridPointInDegrees;
alias longitudeLastInDegrees  = longitudeOfLastGridPointInDegrees;
alias DiInDegrees = iDirectionIncrementInDegrees;
alias DxInDegrees = iDirectionIncrementInDegrees;
alias DjInDegrees = jDirectionIncrementInDegrees;
alias DyInDegrees = jDirectionIncrementInDegrees;

#_if ( missing(Ni) && PLPresent == 1 ) {
#  iterator latlon_reduced(numberOfPoints,missingValue,values,
#      latitudeFirstInDegrees,longitudeFirstInDegrees,
#      latitudeLastInDegrees,longitudeLastInDegrees,
#      Nj,DjInDegrees,pl);
#  nearest latlon_reduced(values,radius,Nj,pl,longitudeFirstInDegrees,longitudeLastInDegrees);
#} else {
#  iterator latlon(numberOfPoints,missingValue,values,
#                  longitudeFirstInDegrees,DiInDegrees  ,
#                  Ni,Nj,iScansNegatively,
#                  latitudeFirstInDegrees, DjInDegrees,jScansPositively,jPointsAreConsecutive);
#  nearest regular(values,radius,Ni,Nj);
#}
meta latLonValues latlonvalues(values);
alias latitudeLongitudeValues=latLonValues;
meta latitudes latitudes(values,0);
meta longitudes longitudes(values,0);
meta distinctLatitudes latitudes(values,1);
meta distinctLongitudes longitudes(values,1);