From eadd8dad92ffd012804b2814408cccc7bc45cd0d Mon Sep 17 00:00:00 2001
From: maurizuki <62178459+maurizuki@users.noreply.github.com>
Date: Mon, 6 Nov 2023 16:52:56 +0100
Subject: [PATCH] Create ExchangeRatesParser.cs

---
 .../ExchangeRatesParser.cs                    | 96 +++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 src/ECB.Data.ExchangeRates/ExchangeRatesParser.cs

diff --git a/src/ECB.Data.ExchangeRates/ExchangeRatesParser.cs b/src/ECB.Data.ExchangeRates/ExchangeRatesParser.cs
new file mode 100644
index 0000000..63790a6
--- /dev/null
+++ b/src/ECB.Data.ExchangeRates/ExchangeRatesParser.cs
@@ -0,0 +1,96 @@
+// Copyright (c) 2023 Maurizio Basaglia
+//
+// Permission is hereby granted, free of charge, to any person
+// obtaining a copy of this software and associated documentation
+// files (the "Software"), to deal in the Software without
+// restriction, including without limitation the rights to use,
+// copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+
+using System.Globalization;
+using System.Xml.Linq;
+
+namespace ECB.Data.ExchangeRates
+{
+    public class ExchangeRatesParser : IExchangeRatesParser
+    {
+        public IEnumerable<ExchangeRate> Parse(string source)
+        {
+            if (string.IsNullOrWhiteSpace(source)) return new List<ExchangeRate>();
+
+            var document = XDocument.Parse(source);
+
+            if (document.Root == null) return new List<ExchangeRate>();
+
+            var genericNamespace = document.Root.GetNamespaceOfPrefix("generic");
+
+            if (genericNamespace == null) return new List<ExchangeRate>();
+
+            var seriesKeyValueName = XName.Get("Value", genericNamespace.NamespaceName);
+            var obsName = XName.Get("Obs", genericNamespace.NamespaceName);
+            var obsDimensionName = XName.Get("ObsDimension", genericNamespace.NamespaceName);
+            var obsValueName = XName.Get("ObsValue", genericNamespace.NamespaceName);
+
+            return document.Descendants(XName.Get("Series", genericNamespace.NamespaceName))
+                .Select(
+                    a =>
+                    {
+                        var seriesKeyValues = a.Descendants(seriesKeyValueName)
+                            .ToDictionary(
+                                b => b.Attribute("id")!.Value,
+                                b => b.Attribute("value")?.Value
+                            );
+                        return new
+                        {
+                            Frequency =
+                                seriesKeyValues.GetValueOrDefault("FREQ"),
+                            Currency =
+                                seriesKeyValues.GetValueOrDefault("CURRENCY"),
+                            CurrencyDenominator =
+                                seriesKeyValues.GetValueOrDefault("CURRENCY_DENOM"),
+                            ExchangeRateType =
+                                seriesKeyValues.GetValueOrDefault("EXR_TYPE"),
+                            SeriesVariation =
+                                seriesKeyValues.GetValueOrDefault("EXR_SUFFIX"),
+                            Obs = a.Descendants(obsName),
+                        };
+                    }
+                )
+                .SelectMany(
+                    a => a.Obs,
+                    (a, b) => new ExchangeRate
+                    {
+                        Frequency = a.Frequency,
+                        Currency = a.Currency,
+                        CurrencyDenominator = a.CurrencyDenominator,
+                        ExchangeRateType = a.ExchangeRateType,
+                        SeriesVariation = a.SeriesVariation,
+                        TimePeriod = b.Descendants(obsDimensionName)
+                            .FirstOrDefault()?.Attribute("value")?.Value,
+                        Value = decimal.TryParse(
+                            b.Descendants(obsValueName)
+                                .FirstOrDefault()?.Attribute("value")?.Value ?? "0",
+                            CultureInfo.InvariantCulture,
+                            out var value
+                        )
+                            ? value
+                            : 0,
+                    }
+                );
+        }
+    }
+}