geojson.go

package spatial

import (
	"encoding/json"
	"errors"
	"fmt"
	"math"
	"strconv"
	"strings"

	"github.com/dolthub/go-mysql-server/sql"
	"github.com/dolthub/go-mysql-server/sql/expression"
	"github.com/dolthub/go-mysql-server/sql/types"
)

// AsGeoJSON is a function that returns a point type from a WKT string
type AsGeoJSON struct {
	expression.NaryExpression
}

var _ sql.FunctionExpression = (*AsGeoJSON)(nil)
var _ sql.CollationCoercible = (*AsGeoJSON)(nil)

// NewAsGeoJSON creates a new point expression.
func NewAsGeoJSON(args ...sql.Expression) (sql.Expression, error) {
	if len(args) < 1 || len(args) > 3 {
		return nil, sql.ErrInvalidArgumentNumber.New("ST_ASGEOJSON", "1, 2, or 3", len(args))
	}
	return &AsGeoJSON{expression.NaryExpression{ChildExpressions: args}}, nil
}

// FunctionName implements sql.FunctionExpression
func (g *AsGeoJSON) FunctionName() string {
	return "st_asgeojson"
}

// Description implements sql.FunctionExpression
func (g *AsGeoJSON) Description() string {
	return "returns a GeoJSON object from the geometry."
}

// Type implements the sql.Expression interface.
func (g *AsGeoJSON) Type() sql.Type {
	return types.JSON
}

// CollationCoercibility implements the interface sql.CollationCoercible.
func (f *AsGeoJSON) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
	return ctx.GetCollation(), 2
}

func (g *AsGeoJSON) String() string {
	var args = make([]string, len(g.ChildExpressions))
	for i, arg := range g.ChildExpressions {
		args[i] = arg.String()
	}
	return fmt.Sprintf("%s(%s)", g.FunctionName(), strings.Join(args, ","))
}

// WithChildren implements the Expression interface.
func (g *AsGeoJSON) WithChildren(children ...sql.Expression) (sql.Expression, error) {
	return NewAsGeoJSON(children...)
}

func PointToSlice(p types.Point) [2]float64 {
	return [2]float64{p.X, p.Y}
}

func LineToSlice(l types.LineString) [][2]float64 {
	arr := make([][2]float64, len(l.Points))
	for i, p := range l.Points {
		arr[i] = PointToSlice(p)
	}
	return arr
}

func PolyToSlice(p types.Polygon) [][][2]float64 {
	arr := make([][][2]float64, len(p.Lines))
	for i, l := range p.Lines {
		arr[i] = LineToSlice(l)
	}
	return arr
}

func MPointToSlice(p types.MultiPoint) [][2]float64 {
	arr := make([][2]float64, len(p.Points))
	for i, point := range p.Points {
		arr[i] = PointToSlice(point)
	}
	return arr
}

func MLineToSlice(p types.MultiLineString) [][][2]float64 {
	arr := make([][][2]float64, len(p.Lines))
	for i, l := range p.Lines {
		arr[i] = LineToSlice(l)
	}
	return arr
}

func MPolyToSlice(p types.MultiPolygon) [][][][2]float64 {
	arr := make([][][][2]float64, len(p.Polygons))
	for i, p := range p.Polygons {
		arr[i] = PolyToSlice(p)
	}
	return arr
}

func GeomCollToSlice(g types.GeomColl) interface{} {
	arr := make([]interface{}, len(g.Geoms))
	for i, geom := range g.Geoms {
		obj := make(map[string]interface{})
		switch v := geom.(type) {
		case types.Point:
			obj["type"] = "Point"
			obj["coordinates"] = PointToSlice(v)
		case types.LineString:
			obj["type"] = "LineString"
			obj["coordinates"] = LineToSlice(v)
		case types.Polygon:
			obj["type"] = "Polygon"
			obj["coordinates"] = PolyToSlice(v)
		case types.MultiPoint:
			obj["type"] = "MultiPoint"
			obj["coordinates"] = MPointToSlice(v)
		case types.MultiLineString:
			obj["type"] = "MultiLineString"
			obj["coordinates"] = MLineToSlice(v)
		case types.MultiPolygon:
			obj["type"] = "MultiPolygon"
			obj["coordinates"] = MPolyToSlice(v)
		case types.GeomColl:
			obj["type"] = "GeometryCollection"
			obj["geometries"] = GeomCollToSlice(v)
		}
		arr[i] = obj
	}

	return arr
}

func FindBBox(v interface{}) [4]float64 {
	var res [4]float64
	switch v := v.(type) {
	case types.Point:
		res = [4]float64{v.X, v.Y, v.X, v.Y}
	case types.LineString:
		res = [4]float64{math.MaxFloat64, math.MaxFloat64, -math.MaxFloat64, -math.MaxFloat64}
		for _, p := range v.Points {
			tmp := FindBBox(p)
			res[0] = math.Min(res[0], tmp[0])
			res[1] = math.Min(res[1], tmp[1])
			res[2] = math.Max(res[2], tmp[2])
			res[3] = math.Max(res[3], tmp[3])
		}
	case types.Polygon:
		res = [4]float64{math.MaxFloat64, math.MaxFloat64, -math.MaxFloat64, -math.MaxFloat64}
		for _, l := range v.Lines {
			tmp := FindBBox(l)
			res[0] = math.Min(res[0], tmp[0])
			res[1] = math.Min(res[1], tmp[1])
			res[2] = math.Max(res[2], tmp[2])
			res[3] = math.Max(res[3], tmp[3])
		}
	case types.MultiPoint:
		res = [4]float64{math.MaxFloat64, math.MaxFloat64, -math.MaxFloat64, -math.MaxFloat64}
		for _, p := range v.Points {
			tmp := FindBBox(p)
			res[0] = math.Min(res[0], tmp[0])
			res[1] = math.Min(res[1], tmp[1])
			res[2] = math.Max(res[2], tmp[2])
			res[3] = math.Max(res[3], tmp[3])
		}
	case types.MultiLineString:
		res = [4]float64{math.MaxFloat64, math.MaxFloat64, -math.MaxFloat64, -math.MaxFloat64}
		for _, l := range v.Lines {
			tmp := FindBBox(l)
			res[0] = math.Min(res[0], tmp[0])
			res[1] = math.Min(res[1], tmp[1])
			res[2] = math.Max(res[2], tmp[2])
			res[3] = math.Max(res[3], tmp[3])
		}
	case types.MultiPolygon:
		res = [4]float64{math.MaxFloat64, math.MaxFloat64, -math.MaxFloat64, -math.MaxFloat64}
		for _, p := range v.Polygons {
			tmp := FindBBox(p)
			res[0] = math.Min(res[0], tmp[0])
			res[1] = math.Min(res[1], tmp[1])
			res[2] = math.Max(res[2], tmp[2])
			res[3] = math.Max(res[3], tmp[3])
		}
	case types.GeomColl:
		res = [4]float64{math.MaxFloat64, math.MaxFloat64, -math.MaxFloat64, -math.MaxFloat64}
		for _, geom := range v.Geoms {
			tmp := FindBBox(geom)
			res[0] = math.Min(res[0], tmp[0])
			res[1] = math.Min(res[1], tmp[1])
			res[2] = math.Max(res[2], tmp[2])
			res[3] = math.Max(res[3], tmp[3])
		}
	}

	return res
}

func RoundFloatSlices(v interface{}, p float64) interface{} {
	switch v := v.(type) {
	case [2]float64:
		return [2]float64{math.Round(v[0]*p) / p, math.Round(v[1]*p) / p}
	case [][2]float64:
		res := make([][2]float64, len(v))
		for i, c := range v {
			res[i] = RoundFloatSlices(c, p).([2]float64)
		}
		return res
	case [][][2]float64:
		res := make([][][2]float64, len(v))
		for i, c := range v {
			res[i] = RoundFloatSlices(c, p).([][2]float64)
		}
		return res
	case [][][][2]float64:
		res := make([][][][2]float64, len(v))
		for i, c := range v {
			res[i] = RoundFloatSlices(c, p).([][][2]float64)
		}
		return res
	}
	return nil
}

// getIntArg is a helper method that evaluates the given sql.Expression to an int type, errors on float32 and float64,
// and returns nil
func getIntArg(ctx *sql.Context, row sql.Row, expr sql.Expression) (interface{}, error) {
	x, err := expr.Eval(ctx, row)
	if err != nil {
		return nil, err
	}
	if x == nil {
		return nil, nil
	}
	switch x.(type) {
	case float32, float64:
		return nil, errors.New("received a float when it should be an int")
	}
	x, _, err = types.Int64.Convert(x)
	if err != nil {
		return nil, err
	}
	return int(x.(int64)), nil
}

// Eval implements the sql.Expression interface.
func (g *AsGeoJSON) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
	// convert spatial type to map, then place inside sql.JSONDocument
	val, err := g.ChildExpressions[0].Eval(ctx, row)
	if err != nil {
		return nil, err
	}

	if val == nil {
		return nil, nil
	}

	obj := make(map[string]interface{})
	switch v := val.(type) {
	case types.Point:
		obj["type"] = "Point"
		obj["coordinates"] = PointToSlice(v)
	case types.LineString:
		obj["type"] = "LineString"
		obj["coordinates"] = LineToSlice(v)
	case types.Polygon:
		obj["type"] = "Polygon"
		obj["coordinates"] = PolyToSlice(v)
	case types.MultiPoint:
		obj["type"] = "MultiPoint"
		obj["coordinates"] = MPointToSlice(v)
	case types.MultiLineString:
		obj["type"] = "MultiLineString"
		obj["coordinates"] = MLineToSlice(v)
	case types.MultiPolygon:
		obj["type"] = "MultiPolygon"
		obj["coordinates"] = MPolyToSlice(v)
	case types.GeomColl:
		obj["type"] = "GeometryCollection"
		obj["geometries"] = GeomCollToSlice(v)
	default:
		return nil, sql.ErrInvalidArgumentType.New(g.FunctionName())
	}

	if len(g.ChildExpressions) == 1 {
		return types.JSONDocument{Val: obj}, nil
	}

	// Evaluate precision
	p, err := getIntArg(ctx, row, g.ChildExpressions[1])
	if err != nil {
		return nil, errors.New("incorrect precision value")
	}
	if p == nil {
		return nil, nil
	}
	pp := p.(int)
	if pp < 0 {
		return nil, errors.New("incorrect precision value")
	}
	if pp > 17 {
		pp = 17
	}

	// Round floats
	prec := math.Pow10(pp)
	if _, ok := obj["coordinates"]; ok {
		obj["coordinates"] = RoundFloatSlices(obj["coordinates"], prec)
	}

	if len(g.ChildExpressions) == 2 {
		return types.JSONDocument{Val: obj}, nil
	}

	// Evaluate flag argument
	f, err := getIntArg(ctx, row, g.ChildExpressions[2])
	if err != nil {
		return nil, errors.New("incorrect flag value")
	}
	if f == nil {
		return nil, nil
	}
	flag := f.(int)
	if flag < 0 || flag > 7 {
		return nil, sql.ErrInvalidArgumentDetails.New(g.FunctionName(), flag)
	}
	// TODO: the flags do very different things for when the SRID is GeoSpatial
	switch flag {
	// Flags 1,3,5 have bounding box
	case 1, 3, 5:
		// Don't find bounding box for empty geometries
		if g, ok := val.(types.GeomColl); ok {
			if len(g.Geoms) == 0 {
				break
			}
		}
		res := FindBBox(val)
		for i, r := range res {
			res[i] = math.Round(r*prec) / prec
			if math.IsInf(res[i], 1) {
				res[i] = math.MaxFloat64
			} else if math.IsInf(res[i], -1) {
				res[i] = -math.MaxFloat64
			}
		}
		obj["bbox"] = res
	// Flag 2 and 4 add CRS URN (EPSG: <srid>); only shows up if SRID != 0
	case 2, 4:
		// CRS obj only shows up if srid != 0
		srid := val.(types.GeometryValue).GetSRID()
		if srid != 0 {
			// Create CRS URN Object
			crs := make(map[string]interface{})
			crs["type"] = "name"

			// Create properties
			props := make(map[string]interface{})
			// Flag 2 is short format CRS URN, while 4 is long format
			sridStr := strconv.Itoa(int(srid))
			if flag == 2 {
				props["name"] = "EPSG:" + sridStr
			} else {
				props["name"] = "urn:ogc:def:crs:EPSG::" + sridStr
			}
			// Add properties to crs
			crs["properties"] = props

			// Add CRS to main object
			obj["crs"] = crs
		}
	}

	return types.JSONDocument{Val: obj}, nil
}

// GeomFromGeoJSON is a function returns a geometry based on a string
type GeomFromGeoJSON struct {
	expression.NaryExpression
}

var _ sql.FunctionExpression = (*GeomFromGeoJSON)(nil)
var _ sql.CollationCoercible = (*GeomFromGeoJSON)(nil)

// NewGeomFromGeoJSON creates a new point expression.
func NewGeomFromGeoJSON(args ...sql.Expression) (sql.Expression, error) {
	if len(args) < 1 || len(args) > 3 {
		return nil, sql.ErrInvalidArgumentNumber.New("ST_GEOMFROMGEOJSON", "1, 2, or 3", len(args))
	}
	return &GeomFromGeoJSON{expression.NaryExpression{ChildExpressions: args}}, nil
}

// FunctionName implements sql.FunctionExpression
func (g *GeomFromGeoJSON) FunctionName() string {
	return "st_geomfromgeojson"
}

// Description implements sql.FunctionExpression
func (g *GeomFromGeoJSON) Description() string {
	return "returns a GeoJSON object from the geometry."
}

// Type implements the sql.Expression interface.
func (g *GeomFromGeoJSON) Type() sql.Type {
	return types.GeometryType{}
}

// CollationCoercibility implements the interface sql.CollationCoercible.
func (*GeomFromGeoJSON) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
	return sql.Collation_binary, 4
}

func (g *GeomFromGeoJSON) String() string {
	var args = make([]string, len(g.ChildExpressions))
	for i, arg := range g.ChildExpressions {
		args[i] = arg.String()
	}
	return fmt.Sprintf("ST_GEOMFROMGEOJSON(%s)", strings.Join(args, ","))
}

// WithChildren implements the Expression interface.
func (g *GeomFromGeoJSON) WithChildren(children ...sql.Expression) (sql.Expression, error) {
	return NewGeomFromGeoJSON(children...)
}

func SliceToPoint(coords interface{}) (interface{}, error) {
	c, ok := coords.([]interface{})
	if !ok {
		return nil, errors.New("member 'coordinates' must be of type 'array'")
	}
	if len(c) < 2 {
		return nil, errors.New("unsupported number of coordinate dimensions")
	}
	x, ok := c[0].(float64)
	if !ok {
		return nil, errors.New("coordinate must be of type number")
	}
	y, ok := c[1].(float64)
	if !ok {
		return nil, errors.New("coordinate must be of type number")
	}
	return types.Point{SRID: types.GeoSpatialSRID, X: x, Y: y}, nil
}

func SliceToLine(coords interface{}) (interface{}, error) {
	cs, ok := coords.([]interface{})
	if !ok {
		return nil, errors.New("member 'coordinates' must be of type 'array'")
	}
	if len(cs) < 2 {
		return nil, errors.New("invalid GeoJSON data provided")
	}
	points := make([]types.Point, len(cs))
	for i, c := range cs {
		p, err := SliceToPoint(c)
		if err != nil {
			return nil, err
		}
		points[i] = p.(types.Point)
	}
	return types.LineString{SRID: types.GeoSpatialSRID, Points: points}, nil
}

func SliceToPoly(coords interface{}) (interface{}, error) {
	// coords must be a slice of slices of at least 2 slices of 2 float64
	cs, ok := coords.([]interface{})
	if !ok {
		return nil, errors.New("member 'coordinates' must be of type 'array'")
	}
	if len(cs) == 0 {
		return nil, errors.New("not enough lines")
	}
	lines := make([]types.LineString, len(cs))
	for i, c := range cs {
		l, err := SliceToLine(c)
		if err != nil {
			return nil, err
		}
		if !isLinearRing(l.(types.LineString)) {
			return nil, errors.New("invalid GeoJSON data provided")
		}
		lines[i] = l.(types.LineString)
	}
	return types.Polygon{SRID: types.GeoSpatialSRID, Lines: lines}, nil
}

func SliceToMPoint(coords interface{}) (interface{}, error) {
	cs, ok := coords.([]interface{})
	if !ok {
		return nil, errors.New("member 'coordinates' must be of type 'array'")
	}
	if len(cs) < 2 {
		return nil, errors.New("invalid GeoJSON data provided")
	}
	points := make([]types.Point, len(cs))
	for i, c := range cs {
		p, err := SliceToPoint(c)
		if err != nil {
			return nil, err
		}
		points[i] = p.(types.Point)
	}
	return types.MultiPoint{SRID: types.GeoSpatialSRID, Points: points}, nil
}

func SliceToMLine(coords interface{}) (interface{}, error) {
	// coords must be a slice of slices of at least 2 slices of 2 float64
	cs, ok := coords.([]interface{})
	if !ok {
		return nil, errors.New("member 'coordinates' must be of type 'array'")
	}
	if len(cs) == 0 {
		return nil, errors.New("not enough lines")
	}
	lines := make([]types.LineString, len(cs))
	for i, c := range cs {
		l, err := SliceToLine(c)
		if err != nil {
			return nil, err
		}
		lines[i] = l.(types.LineString)
	}
	return types.MultiLineString{SRID: types.GeoSpatialSRID, Lines: lines}, nil
}

func SliceToMPoly(coords interface{}) (interface{}, error) {
	// coords must be a slice of slices of slices at least 4 slices of 2 float64
	cs, ok := coords.([]interface{})
	if !ok {
		return nil, errors.New("member 'coordinates' must be of type 'array'")
	}
	if len(cs) == 0 {
		return nil, errors.New("not enough polygons")
	}
	polys := make([]types.Polygon, len(cs))
	for i, c := range cs {
		p, err := SliceToPoly(c)
		if err != nil {
			return nil, err
		}
		polys[i] = p.(types.Polygon)
	}
	return types.MultiPolygon{SRID: types.GeoSpatialSRID, Polygons: polys}, nil
}

func SliceToGeomColl(geometries interface{}) (interface{}, error) {
	// geomObjs should be a slice of geojsons
	geomObjs, ok := geometries.([]interface{})
	if !ok {
		return nil, errors.New("member 'geometries' must be of type 'array'")
	}

	geoms := make([]types.GeometryValue, len(geomObjs))
	for i, o := range geomObjs {
		obj, ok := o.(map[string]interface{})
		if !ok {
			return nil, errors.New("member 'geometries' must be of type 'object'")
		}
		res, _, err := ParseGeoJsonData(obj)
		if err != nil {
			return nil, err
		}
		geoms[i] = res.(types.GeometryValue)
	}
	return types.GeomColl{SRID: types.GeoSpatialSRID, Geoms: geoms}, nil
}

func ParseGeoJsonData(obj map[string]interface{}) (interface{}, string, error) {
	geomType, ok := obj["type"]
	if !ok {
		return nil, "", errors.New("missing required member 'type'")
	}

	gt, ok := geomType.(string)
	if !ok {
		return nil, "", errors.New("member 'type' must be of type 'string'")
	}

	var res interface{}
	var err error
	switch gt {
	case "Point":
		coords, ok := obj["coordinates"]
		if !ok {
			return nil, "", errors.New("missing required member 'coordinates'")
		}
		res, err = SliceToPoint(coords)
	case "LineString":
		coords, ok := obj["coordinates"]
		if !ok {
			return nil, "", errors.New("missing required member 'coordinates'")
		}
		res, err = SliceToLine(coords)
	case "Polygon":
		coords, ok := obj["coordinates"]
		if !ok {
			return nil, "", errors.New("missing required member 'coordinates'")
		}
		res, err = SliceToPoly(coords)
	case "MultiPoint":
		coords, ok := obj["coordinates"]
		if !ok {
			return nil, "", errors.New("missing required member 'coordinates'")
		}
		res, err = SliceToMPoint(coords)
	case "MultiLineString":
		coords, ok := obj["coordinates"]
		if !ok {
			return nil, "", errors.New("missing required member 'coordinates'")
		}
		res, err = SliceToMLine(coords)
	case "MultiPolygon":
		coords, ok := obj["coordinates"]
		if !ok {
			return nil, "", errors.New("missing required member 'coordinates'")
		}
		res, err = SliceToMPoly(coords)
	case "GeometryCollection":
		geoms, ok := obj["geometries"]
		if !ok {
			return nil, "", errors.New("missing required member 'geometries'")
		}
		res, err = SliceToGeomColl(geoms)
	case "Feature":
		geom, ok := obj["geometry"]
		if !ok {
			return nil, "", errors.New("missing required member 'geometry'")
		}
		geomObj, ok := geom.(map[string]interface{})
		if !ok {
			return nil, "", errors.New("member 'geometry' must be of type 'object'")
		}
		// TODO: figure out what properties is used for
		props, ok := obj["properties"]
		if !ok {
			return nil, "", errors.New("missing required member 'properties'")
		}
		_, ok = props.(map[string]interface{})
		if !ok {
			return nil, "", errors.New("member 'properties' must be of type 'object'")
		}
		res, gt, err = ParseGeoJsonData(geomObj)
	case "FeatureCollection":
		feats, ok := obj["features"]
		if !ok {
			return nil, "", errors.New("missing required member 'features'")
		}
		res, err = SliceToGeomColl(feats)
	default:
		return nil, "", errors.New("member 'type' is wrong")
	}
	return res, gt, err
}

// Eval implements the sql.Expression interface.
func (g *GeomFromGeoJSON) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
	val, err := g.ChildExpressions[0].Eval(ctx, row)
	if err != nil {
		return nil, err
	}
	if val == nil {
		return nil, nil
	}
	val, _, err = types.LongBlob.Convert(val)
	if err != nil {
		return nil, err
	}

	switch s := val.(type) {
	case string:
		val = []byte(s)
	case []byte:
		val = s
	}

	var obj map[string]interface{}
	err = json.Unmarshal(val.([]byte), &obj)
	if err != nil {
		return nil, err
	}

	// Create type accordingly
	res, geomType, err := ParseGeoJsonData(obj)
	if err != nil {
		return nil, err
	}
	if len(g.ChildExpressions) == 1 {
		return res, nil
	}

	// Evaluate flag argument
	f, err := getIntArg(ctx, row, g.ChildExpressions[1])
	if err != nil {
		return nil, errors.New("incorrect flag value")
	}
	if f == nil {
		return nil, nil
	}
	flag := f.(int)
	if flag < 1 || flag > 4 {
		return nil, sql.ErrInvalidArgumentDetails.New(g.FunctionName(), flag)
	}
	// reject higher dimensions; otherwise, higher dimensions are already stripped off
	if flag == 1 {
		switch geomType {
		case "Point":
			if len(obj["coordinates"].([]interface{})) > 2 {
				return nil, errors.New("unsupported number of coordinate dimensions")
			}
		case "LineString", "MultiPoint":
			for _, a := range obj["coordinates"].([]interface{}) {
				if len(a.([]interface{})) > 2 {
					return nil, errors.New("unsupported number of coordinate dimensions")
				}
			}
		case "Polygon", "MultiLineString":
			for _, a := range obj["coordinates"].([]interface{}) {
				for _, b := range a.([]interface{}) {
					if len(b.([]interface{})) > 2 {
						return nil, errors.New("unsupported number of coordinate dimensions")
					}
				}
			}
		case "MultiPolygon":
			for _, a := range obj["coordinates"].([]interface{}) {
				for _, b := range a.([]interface{}) {
					for _, c := range b.([]interface{}) {
						if len(c.([]interface{})) > 2 {
							return nil, errors.New("unsupported number of coordinate dimensions")
						}
					}
				}
			}
		}
	}
	if len(g.ChildExpressions) == 2 {
		return res, nil
	}

	// Evaluate SRID
	s, err := getIntArg(ctx, row, g.ChildExpressions[2])
	if err != nil {
		return nil, errors.New("incorrect srid value")
	}
	if err = types.ValidateSRID(s.(int), g.FunctionName()); err != nil {
		return nil, err
	}
	srid := uint32(s.(int))
	res = res.(types.GeometryValue).SetSRID(srid)
	return res, nil
}