Break down purchase receipts by cost/commission, harden XML validation and state I/O

Adds a full pre-load validation pass for GM XML seeds (ids, names,
options, commission, LMSR liquidity), replaces IO.print with
System.out, and surfaces detailed error messages across load/save
commands instead of generic failures.

5 files changed, 142 insertions, 27 deletions

diff --git a/service/src/main/java/market/guess/service/LocalGuessMarketContext.java b/service/src/main/java/market/guess/service/LocalGuessMarketContext.java
index 909a808..f04324b 100644
--- a/service/src/main/java/market/guess/service/LocalGuessMarketContext.java
+++ b/service/src/main/java/market/guess/service/LocalGuessMarketContext.java
@@ -10,6 +10,7 @@ import market.guess.model.event.EventDetailDTO;
 import market.guess.service.catalog.infrastructure.MarketContext;
 import market.guess.service.domain.Order;
 import market.guess.service.fulfillment.FulfillmentContext;
+import market.guess.service.helpers.BigDecimalOptions;
 import market.guess.service.helpers.InstantOptions;
 import market.guess.service.matching.MatchingEngine;
 import market.guess.service.risk.RiskEngine;
@@ -55,6 +56,20 @@ public final class LocalGuessMarketContext implements GuessMarketContext {
 
     var rawTrades = matching.match(order);
     var trades = fulfillment.fulfill(user, order, rawTrades);
+
+    var totalSharesCost =
+        trades.stream()
+            .map(t -> t.sharesCost())
+            .reduce(BigDecimalOptions.ZERO_MONEY, BigDecimal::add);
+    var totalCommission =
+        trades.stream()
+            .map(t -> t.commission())
+            .reduce(BigDecimalOptions.ZERO_MONEY, BigDecimal::add);
+    var totalPaid =
+        trades.stream()
+            .map(t -> t.totalPaid())
+            .reduce(BigDecimalOptions.ZERO_MONEY, BigDecimal::add);
+
     return Result.ok(
         new PurchaseReceiptDTO(
             trades.stream()
@@ -65,8 +80,11 @@ public final class LocalGuessMarketContext implements GuessMarketContext {
                             t.buyerUserName(),
                             t.marketName(),
                             String.valueOf(t.quantity()),
-                            t.totalPaid().toPlainString()))
+                            t.sharesCost().toPlainString()))
                 .toList(),
+            totalSharesCost.toPlainString(),
+            totalCommission.toPlainString(),
+            totalPaid.toPlainString(),
             event.toMarketState()));
   }
 
diff --git a/service/src/main/java/market/guess/service/catalog/infrastructure/MarketContext.java b/service/src/main/java/market/guess/service/catalog/infrastructure/MarketContext.java
index cb2b467..5fc2e24 100644
--- a/service/src/main/java/market/guess/service/catalog/infrastructure/MarketContext.java
+++ b/service/src/main/java/market/guess/service/catalog/infrastructure/MarketContext.java
@@ -67,15 +67,22 @@ public final class MarketContext {
           GSON.toJson(new Wrapper(events.getAll(), users.getAll())),
           StandardCharsets.UTF_8);
     } catch (Exception e) {
-      throw new GuessMarketException("Failed to sove the file.");
+      throw new GuessMarketException("Failed to save state to " + target + ": " + e.getMessage());
     }
   }
 
   public void load(Path path) throws GuessMarketException {
+    var target = withJsonExtension(path);
+    if (!Files.isRegularFile(target)) {
+      throw new GuessMarketException("State file not found: " + target);
+    }
     try {
       var wrapper =
           GSON.fromJson(
-              Files.readString(withJsonExtension(path), StandardCharsets.UTF_8), Wrapper.class);
+              Files.readString(target, StandardCharsets.UTF_8), Wrapper.class);
+      if (wrapper == null || wrapper.events() == null) {
+        throw new GuessMarketException("State file contains invalid or empty data.");
+      }
       events.clear();
       users.clear();
 
@@ -88,14 +95,15 @@ public final class MarketContext {
       }
 
     } catch (JsonSyntaxException e) {
-      throw new GuessMarketException("The JSON file is malformed.");
+      throw new GuessMarketException("The state file is malformed JSON: " + e.getMessage());
     } catch (IOException e) {
-      throw new GuessMarketException("Unable the file.");
+      throw new GuessMarketException("Unable to read state file: " + e.getMessage());
     }
   }
 
   private static Path withJsonExtension(Path path) {
+    if (path == null) return null;
     var name = path.getFileName().toString();
-    return name.endsWith(".json") ? path : path.resolveSibling(name + ".json");
+    return name.toLowerCase().endsWith(".json") ? path : path.resolveSibling(name + ".json");
   }
 }
diff --git a/service/src/main/java/market/guess/service/catalog/infrastructure/mapper/v1/EventMapperV1.java b/service/src/main/java/market/guess/service/catalog/infrastructure/mapper/v1/EventMapperV1.java
index f45eb46..b9c43bb 100644
--- a/service/src/main/java/market/guess/service/catalog/infrastructure/mapper/v1/EventMapperV1.java
+++ b/service/src/main/java/market/guess/service/catalog/infrastructure/mapper/v1/EventMapperV1.java
@@ -19,8 +19,8 @@ public final class EventMapperV1 implements Mapper<GMEvent, Event> {
     return new Event(
         getEventKey(source),
         source.getId(),
-        joinName(source.getName()),
-        source.getDescription(),
+        joinName(source.getName()).trim(),
+        source.getDescription() != null ? source.getDescription().trim() : "",
         source.getComision().getValue(),
         getTiming(source.getComision().getType()),
         new LmsrTradingMechanism(source.getGMMethod().getGMLMSR().getB(), options.size()),
@@ -38,17 +38,20 @@ public final class EventMapperV1 implements Mapper<GMEvent, Event> {
   }
 
   private static CommissionTiming getTiming(String type) throws IllegalArgumentException {
-    return switch (type) {
+    if (type == null) throw new IllegalArgumentException("Commission type cannot be null");
+    return switch (type.toLowerCase().trim()) {
       case "on-close" -> CommissionTiming.ON_CLOSE;
       case "on-purchase" -> CommissionTiming.ON_PURCHASE;
-      default -> throw new IllegalArgumentException("Unknown comision type: " + type);
+      default -> throw new IllegalArgumentException("Unknown commission type: " + type);
     };
   }
 
   private static List<Market> getOptions(GMEvent x) {
-    var ret = new ArrayList<Market>(x.getGMOptions().getGMOption().size());
-    for (var i = 0; i < x.getGMOptions().getGMOption().size(); i++) {
-      ret.add(new Market(getEventKey(x) + ":" + i, x.getGMOptions().getGMOption().get(i)));
+    var raw = x.getGMOptions().getGMOption();
+    var ret = new ArrayList<Market>(raw.size());
+    for (var i = 0; i < raw.size(); i++) {
+      var opt = raw.get(i);
+      ret.add(new Market(getEventKey(x) + ":" + i, opt != null ? opt.trim() : ""));
     }
     return ret;
   }
diff --git a/service/src/main/java/market/guess/service/catalog/infrastructure/provider/v1/XMLLoaderV1.java b/service/src/main/java/market/guess/service/catalog/infrastructure/provider/v1/XMLLoaderV1.java
index bcae787..44e1c7f 100644
--- a/service/src/main/java/market/guess/service/catalog/infrastructure/provider/v1/XMLLoaderV1.java
+++ b/service/src/main/java/market/guess/service/catalog/infrastructure/provider/v1/XMLLoaderV1.java
@@ -2,8 +2,10 @@ package market.guess.service.catalog.infrastructure.provider.v1;
 
 import jakarta.xml.bind.JAXBContext;
 import jakarta.xml.bind.JAXBException;
+import java.math.BigDecimal;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.ArrayList;
 import market.guess.api.CatalogContext;
 import market.guess.api.LoadResult;
 import market.guess.api.Result;
@@ -12,6 +14,7 @@ import market.guess.service.catalog.infrastructure.provider.Loader;
 import market.guess.service.catalog.infrastructure.repository.EventRepository;
 import market.guess.service.catalog.infrastructure.repository.UserRepository;
 import market.guess.service.catalog.model.v1.GuessMarket;
+import market.guess.service.domain.Event;
 import market.guess.service.domain.User;
 
 public final class XMLLoaderV1 implements Loader {
@@ -35,19 +38,23 @@ public final class XMLLoaderV1 implements Loader {
     try {
       context = JAXBContext.newInstance(GuessMarket.class);
     } catch (JAXBException e) {
-      throw new IllegalStateException();
+      throw new IllegalStateException("Failed to initialize JAXB context: " + e.getMessage(), e);
     }
   }
 
   @Override
   public Result<LoadResult> load(Path path) {
+    if (path == null) {
+      return Result.error("INVALID_PATH", "File path cannot be null.");
+    }
+
     if (!Files.isRegularFile(path)) {
-      return Result.error("FILE_NOT_FOUND", "No such file.");
+      return Result.error("FILE_NOT_FOUND", "No such file: " + path);
     }
 
     if (path.getFileName() == null
         || !path.getFileName().toString().toLowerCase().endsWith(".xml")) {
-      return Result.error("NOT_XML", "The file must be an XML.");
+      return Result.error("NOT_XML", "The file must have a .xml extension.");
     }
 
     try (var stream = Files.newInputStream(path)) {
@@ -59,21 +66,34 @@ public final class XMLLoaderV1 implements Loader {
         return Result.error(validation.getMessage(), validation.getDetails());
       }
 
+      var domainEvents = new ArrayList<Event>();
       for (var event : seed.getGMEvents().getGMEvent()) {
-        eventRepository.add(mapper.toDomain(event));
+        domainEvents.add(mapper.toDomain(event));
+      }
+
+      eventRepository.clear();
+      userRepository.clear();
+
+      for (var domainEvent : domainEvents) {
+        eventRepository.add(domainEvent);
       }
 
-      userRepository.add(new User("Tester", 500));
+      userRepository.add(new User("Tester", new BigDecimal("500.00")));
 
       return Result.ok(new LoadResult(path.toString(), eventRepository.getAll().size()));
+    } catch (JAXBException e) {
+      var cause =
+          e.getLinkedException() != null ? e.getLinkedException().getMessage() : e.getMessage();
+      return Result.error(
+          "XML_PARSE_ERROR",
+          "The XML file is malformed or invalid: " + (cause != null ? cause : e.getMessage()));
     } catch (Exception e) {
-      return Result.error("UNREADABLE", "The file could not be read.");
+      return Result.error("UNREADABLE", "The file could not be read: " + e.getMessage());
     }
   }
 
   @Override
   public Result<LoadResult> seed(CatalogContext context) {
-    // TODO Auto-generated method stub
     throw new UnsupportedOperationException("Unimplemented method 'seed'");
   }
 }
diff --git a/service/src/main/java/market/guess/service/catalog/infrastructure/provider/v1/XMLValidatorV1.java b/service/src/main/java/market/guess/service/catalog/infrastructure/provider/v1/XMLValidatorV1.java
index 567558a..5a4e5ea 100644
--- a/service/src/main/java/market/guess/service/catalog/infrastructure/provider/v1/XMLValidatorV1.java
+++ b/service/src/main/java/market/guess/service/catalog/infrastructure/provider/v1/XMLValidatorV1.java
@@ -9,27 +9,93 @@ public final class XMLValidatorV1 {
   private static final int MAX_COMMISSION = 90;
 
   public Result<Void> validate(GuessMarket seed) {
+    if (seed == null || seed.getGMEvents() == null || seed.getGMEvents().getGMEvent() == null) {
+      return Result.error("INVALID_XML", "The XML file contains no GM-events element.");
+    }
 
-    var seenIds = new HashSet<Integer>();
-    var duplicated = new HashSet<Integer>();
+    var events = seed.getGMEvents().getGMEvent();
+    if (events.isEmpty()) {
+      return Result.error("EMPTY_EVENTS", "The XML file does not contain any events.");
+    }
 
-    for (var e : seed.getGMEvents().getGMEvent()) {
+    var seenIds = new HashSet<Integer>();
 
-      if (!seenIds.add(e.getId()) && duplicated.add(e.getId())) {
+    for (var e : events) {
+      // 1. Event ID must be positive integer (> 0)
+      if (e.getId() <= 0) {
+        return Result.error(
+            "INVALID_ID",
+            "Event ID must be a positive integer (> 0), found: " + e.getId());
+      }
+      if (!seenIds.add(e.getId())) {
         return Result.error(
             "DUPLICATE_ID",
-            "Event id " + e.getId() + " appears more than once, every event id must be unique.");
+            "Event ID " + e.getId() + " appears more than once. Every event ID must be unique.");
       }
 
+      // 2. Event name must not be empty
+      if (e.getName() == null || e.getName().isEmpty() || String.join(" ", e.getName()).isBlank()) {
+        return Result.error("MISSING_NAME", "Event ID " + e.getId() + " has an empty name.");
+      }
+
+      // 3. Event description must not be empty
+      if (e.getDescription() == null || e.getDescription().isBlank()) {
+        return Result.error("MISSING_DESCRIPTION", "Event ID " + e.getId() + " has an empty description.");
+      }
+
+      // 4. Commission validation
+      if (e.getComision() == null) {
+        return Result.error("MISSING_COMMISSION", "Event ID " + e.getId() + " is missing commission.");
+      }
       var pct = e.getComision().getValue();
       if (pct < MIN_COMMISSION || pct > MAX_COMMISSION) {
         return Result.error(
             "COMMISSION_OUT_OF_RANGE",
-            "Commission is %d%%, it must be between %d%% and %d%%."
-                .formatted(pct, MIN_COMMISSION, MAX_COMMISSION));
+            "Event ID " + e.getId() + " commission is " + pct + "%. It must be between " + MIN_COMMISSION + "% and " + MAX_COMMISSION + "%.");
+      }
+
+      var type = e.getComision().getType();
+      if (type == null || (!type.equalsIgnoreCase("on-close") && !type.equalsIgnoreCase("on-purchase"))) {
+        return Result.error(
+            "INVALID_COMMISSION_TYPE",
+            "Event ID " + e.getId() + " has invalid commission type '" + type + "'. Must be 'on-close' or 'on-purchase'.");
+      }
+
+      // 5. GM-options validation (exactly 2 options for Exercise 1)
+      if (e.getGMOptions() == null || e.getGMOptions().getGMOption() == null) {
+        return Result.error("MISSING_OPTIONS", "Event ID " + e.getId() + " is missing GM-options.");
+      }
+      var options = e.getGMOptions().getGMOption();
+      if (options.size() != 2) {
+        return Result.error(
+            "INVALID_OPTIONS_COUNT",
+            "Event ID " + e.getId() + " must have exactly 2 options for Exercise 1, but found " + options.size() + ".");
+      }
+      var opt0 = options.get(0) == null ? "" : options.get(0).trim();
+      var opt1 = options.get(1) == null ? "" : options.get(1).trim();
+      if (opt0.isEmpty() || opt1.isEmpty()) {
+        return Result.error("EMPTY_OPTION", "Event ID " + e.getId() + " has an empty option name.");
+      }
+      if (opt0.equalsIgnoreCase(opt1)) {
+        return Result.error("DUPLICATE_OPTION", "Event ID " + e.getId() + " has duplicate option names: '" + opt0 + "'.");
+      }
+
+      // 6. GM-method and LMSR validation
+      if (e.getGMMethod() == null) {
+        return Result.error("MISSING_METHOD", "Event ID " + e.getId() + " is missing GM-method.");
+      }
+      if (e.getGMMethod().getGMLMSR() == null) {
+        return Result.error("INVALID_METHOD", "Event ID " + e.getId() + " must use LMSR trading method in Exercise 1.");
+      }
+      var b = e.getGMMethod().getGMLMSR().getB();
+      if (b <= 0) {
+        return Result.error(
+            "INVALID_LIQUIDITY",
+            "Event ID " + e.getId() + " has invalid liquidity b=" + b + ". b must be a positive integer (> 0).");
       }
     }
 
     return Result.ok();
   }
 }
+