package gfs

// Cross-variant constants. Per-variant geometry (latitudes, longitudes,
// pressure levels, hour step, max hour, URL token) lives on the Variant
// type; see variant.go.

const (
	// NumVariables is the number of dataset variables: HGT, UGRD, VGRD.
	NumVariables = 3
	// ElementSize is the cell size in bytes (float32).
	ElementSize = 4

	// LatStart is the first latitude in the cube (south to north).
	LatStart = -90.0
	// LonStart is the first longitude in the cube (0..360 east).
	LonStart = 0.0

	// Variable indices within the cube's 3rd axis.
	VarHeight = 0
	VarWindU  = 1
	VarWindV  = 2
)

// LevelSet identifies which GRIB file (primary or secondary) carries a
// pressure level.
type LevelSet int

const (
	LevelSetA LevelSet = iota // pgrb2 — primary file
	LevelSetB                 // pgrb2b — secondary file
)

// S3BaseURL is the public NOAA S3 mirror.
const S3BaseURL = "https://noaa-gfs-bdp-pds.s3.amazonaws.com"