1 files changed, 129 insertions, 0 deletions
diff --git a/parser.go b/parser.go
new file mode 100644
index 0000000..6cb67e8
--- /dev/null
+++ b/parser.go
@@ -0,0 +1,129 @@
+// parser.go - XML parsing and data extraction
+package main
+
+import (
+	"encoding/xml"
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+)
+
+// ParseForecastXML parses XML response into ForecastData
+func ParseForecastXML(xmlData []byte) (*ForecastData, error) {
+	var fc FeatureCollection
+	if err := xml.Unmarshal(xmlData, &fc); err != nil {
+		return nil, fmt.Errorf("unmarshaling XML: %w", err)
+	}
+
+	if len(fc.Members) == 0 {
+		return nil, fmt.Errorf("no data found in response")
+	}
+
+	mpc := fc.Members[0].GridSeriesObservation.Result.MultiPointCoverage
+
+	// Parse positions
+	lat, lon, times, err := parsePositions(mpc.DomainSet.SimpleMultiPoint.Positions)
+	if err != nil {
+		return nil, fmt.Errorf("parsing positions: %w", err)
+	}
+
+	// Parse parameters
+	params := make([]string, 0, len(mpc.RangeType.DataRecord.Fields))
+	paramIndex := make(map[string]int)
+	for i, f := range mpc.RangeType.DataRecord.Fields {
+		params = append(params, f.Name)
+		paramIndex[f.Name] = i
+	}
+
+	// Parse values
+	values, err := parseTupleList(mpc.RangeSet.DataBlock.TupleList, len(times), len(params))
+	if err != nil {
+		return nil, fmt.Errorf("parsing values: %w", err)
+	}
+
+	return &ForecastData{
+		Latitude:   lat,
+		Longitude:  lon,
+		Timezone:   "Europe/Helsinki", // Default, could be parsed from XML
+		Timestamps: times,
+		Parameters: params,
+		Values:     values,
+		ParamIndex: paramIndex,
+	}, nil
+}
+
+func parsePositions(positionsStr string) (lat, lon float64, times []int64, err error) {
+	lines := strings.Split(strings.TrimSpace(positionsStr), "\n")
+
+	for i, line := range lines {
+		line = strings.TrimSpace(line)
+		if line == "" {
+			continue
+		}
+
+		parts := strings.Fields(line)
+		if len(parts) != 3 {
+			return 0, 0, nil, fmt.Errorf("invalid position format at line %d: %s", i, line)
+		}
+
+		parsedLat, err := strconv.ParseFloat(parts[0], 64)
+		if err != nil {
+			return 0, 0, nil, fmt.Errorf("parsing latitude: %w", err)
+		}
+
+		parsedLon, err := strconv.ParseFloat(parts[1], 64)
+		if err != nil {
+			return 0, 0, nil, fmt.Errorf("parsing longitude: %w", err)
+		}
+
+		timestamp, err := strconv.ParseInt(parts[2], 10, 64)
+		if err != nil {
+			return 0, 0, nil, fmt.Errorf("parsing timestamp: %w", err)
+		}
+
+		if i == 0 {
+			lat, lon = parsedLat, parsedLon
+		} else if math.Abs(parsedLat-lat) > 0.001 || math.Abs(parsedLon-lon) > 0.001 {
+			return 0, 0, nil, fmt.Errorf("inconsistent location at line %d", i)
+		}
+
+		times = append(times, timestamp)
+	}
+
+	if len(times) == 0 {
+		return 0, 0, nil, fmt.Errorf("no positions found")
+	}
+
+	return lat, lon, times, nil
+}
+
+func parseTupleList(tupleStr string, numPoints, numParams int) ([][]float64, error) {
+	tupleStr = strings.TrimSpace(tupleStr)
+	valuesStr := strings.Fields(tupleStr)
+
+	if len(valuesStr) != numPoints*numParams {
+		return nil, fmt.Errorf("data mismatch: expected %d values, got %d",
+			numPoints*numParams, len(valuesStr))
+	}
+
+	values := make([][]float64, numPoints)
+	for i := 0; i < numPoints; i++ {
+		row := make([]float64, numParams)
+		for j := 0; j < numParams; j++ {
+			valStr := valuesStr[i*numParams+j]
+			if valStr == "NaN" {
+				row[j] = math.NaN()
+			} else {
+				val, err := strconv.ParseFloat(valStr, 64)
+				if err != nil {
+					return nil, fmt.Errorf("parsing value at [%d][%d]: %w", i, j, err)
+				}
+				row[j] = val
+			}
+		}
+		values[i] = row
+	}
+
+	return values, nil
+}