feat: add nem12 parser

src/AEMO.MDFF/NEM12/Nem12Reader.cs

@@ -0,0 +1,120 @@
+using System.Globalization;
+using System.Runtime.CompilerServices;
+using AEMO.MDFF.Abstractions;
+using Sylvan.Data.Csv;
+
+namespace AEMO.MDFF.NEM12;
+
+public class Nem12Reader() : IMdffReader
+{
+    private readonly Dictionary<string, int> _nmiIntervalLengths = new();
+
+    public async IAsyncEnumerable<IMdffRecord> ReadAsync(Stream stream, [EnumeratorCancellation] CancellationToken ct)
+    {
+        using var sr = new StreamReader(stream);
+        await using var csv = await CsvDataReader.CreateAsync(sr,
+            new CsvDataReaderOptions()
+            {
+                HasHeaders = false,
+            }, ct);
+
+        bool headerFound = false;
+        bool endFound = false;
+        string currentNMI = null;
+
+        while (await csv.ReadAsync(ct) && !endFound)
+        {
+            var recordIndicator = csv.GetString(0);
+            switch (recordIndicator)
+            {
+                case "100":
+                    if (headerFound)
+                        throw new InvalidDataException("Multiple header records found");
+                    var hr = ParseHeaderRecord(csv);
+                    headerFound = true;
+                    yield return hr;
+                    break;
+                case "200":
+                    if (!headerFound)
+                        throw new InvalidDataException("Data record found before header");
+                    var ddr = ParseNMIDataDetailsRecord(csv);
+                    currentNMI = ddr.NMI;
+                    _nmiIntervalLengths[currentNMI] = ddr.IntervalLength;
+                    yield return ddr;
+                    break;
+                case "300":
+                    if (!headerFound)
+                        throw new InvalidDataException("Data record found before header");
+                    var idr = ParseIntervalDataRecord(csv, currentNMI);
+                    yield return idr;
+                    break;
+                case "400":
+                    if (!headerFound)
+                        throw new InvalidDataException("Data record found before header");
+                    break;
+                case "500":
+                    if (!headerFound)
+                        throw new InvalidDataException("Data record found before header");
+                    break;
+                case "900":
+                    var er = new EndRecord();
+                    endFound = true;
+                    yield return er;
+                    break;
+                default:
+                    throw new InvalidDataException($"Unsupported record indicator: {recordIndicator}");
+            }
+        }
+        if (!headerFound)
+            throw new InvalidDataException("No header record found");
+        if (!endFound)
+            throw new InvalidDataException("No end record found");
+    }
+
+    private HeaderRecord ParseHeaderRecord(CsvDataReader csv)
+    {
+        var dateTimeString = csv.GetString(2);
+        var dateTime = DateTime.ParseExact(dateTimeString, "yyyyMMddHHmmss", CultureInfo.InvariantCulture);
+
+        return new HeaderRecord()
+        {
+            VersionHeader = csv.GetString(1),
+            DateTime = dateTime,
+            FromParticipant = csv.GetString(3),
+            ToParticipant = csv.GetString(4)
+        };
+    }
+    private NMIDataDetailsRecord ParseNMIDataDetailsRecord(CsvDataReader csv)
+    {
+        var dateString = csv.GetString(9);
+        var date = DateTime.ParseExact(dateString, "yyyyMMdd", CultureInfo.InvariantCulture);
+
+        return new NMIDataDetailsRecord
+        {
+            NMI = csv.GetString(1),
+            NMIConfiguration = csv.GetString(2),
+            RegisterId = csv.GetString(3),
+            NMISuffix = csv.GetString(4),
+            MDMDataStreamIdentifier = csv.GetString(5),
+            MeterSerialNumber = csv.GetString(6),
+            UOM = csv.GetString(7),
+            IntervalLength = csv.GetInt32(8),
+            NextScheduledReadDate = date
+        };
+    }
+
+    private IntervalDataRecord ParseIntervalDataRecord(CsvDataReader csv, string currentNMI)
+    {
+        var dateString = csv.GetString(1);
+        var date = DateTime.ParseExact(dateString, "yyyyMMdd", CultureInfo.InvariantCulture);
+        int intervalLength = _nmiIntervalLengths[currentNMI];
+        int expectedIntervals = 1440 / intervalLength; // 1440 minutes in a day
+
+        return new IntervalDataRecord
+        {
+            IntervalDate = date
+            // TODO: parse interval values
+        };
+    }
+
+}