From 2578f0a6b4c8f22e14db65d6cbc5784d66e3b38b Mon Sep 17 00:00:00 2001
From: aNNiMON <annimon119@gmail.com>
Date: Sat, 30 Sep 2023 23:55:00 +0300
Subject: [PATCH] Add parse errors formatter

---
 .../main/java/com/annimon/ownlang/Main.java   |  4 +-
 .../stages/ParseErrorsFormatterStage.java     | 62 +++++++++++++++++++
 2 files changed, 65 insertions(+), 1 deletion(-)
 create mode 100644 ownlang-parser/src/main/java/com/annimon/ownlang/stages/ParseErrorsFormatterStage.java

diff --git a/ownlang-desktop/src/main/java/com/annimon/ownlang/Main.java b/ownlang-desktop/src/main/java/com/annimon/ownlang/Main.java
index 517748a..ccd0d7a 100644
--- a/ownlang-desktop/src/main/java/com/annimon/ownlang/Main.java
+++ b/ownlang-desktop/src/main/java/com/annimon/ownlang/Main.java
@@ -154,7 +154,9 @@ public final class Main {
                     .then(scopedStages.create("Execution", new ExecutionStage()))
                     .perform(stagesData, input);
         } catch (OwnLangParserException ex) {
-            System.err.println(ex.getParseErrors());
+            final var error = new ParseErrorsFormatterStage()
+                    .perform(stagesData, ex.getParseErrors());
+            System.err.println(error);
         } catch (StoppedException ex) {
             // skip
         } catch (Exception ex) {
diff --git a/ownlang-parser/src/main/java/com/annimon/ownlang/stages/ParseErrorsFormatterStage.java b/ownlang-parser/src/main/java/com/annimon/ownlang/stages/ParseErrorsFormatterStage.java
new file mode 100644
index 0000000..5864dd9
--- /dev/null
+++ b/ownlang-parser/src/main/java/com/annimon/ownlang/stages/ParseErrorsFormatterStage.java
@@ -0,0 +1,62 @@
+package com.annimon.ownlang.stages;
+
+import com.annimon.ownlang.Console;
+import com.annimon.ownlang.parser.Pos;
+import com.annimon.ownlang.parser.Range;
+import com.annimon.ownlang.parser.error.ParseError;
+import com.annimon.ownlang.parser.error.ParseErrors;
+
+public class ParseErrorsFormatterStage implements Stage<ParseErrors, String> {
+
+    @Override
+    public String perform(StagesData stagesData, ParseErrors input) {
+        final var sb = new StringBuilder();
+        final String source = stagesData.get(SourceLoaderStage.TAG_SOURCE);
+        final var lines = source.split("\r?\n");
+        for (ParseError parseError : input) {
+            sb.append(Console.newline());
+            sb.append(parseError);
+            sb.append(Console.newline());
+            final Range range = parseError.range().normalize();
+            printPosition(sb, range, lines);
+            if (parseError.hasStackTrace()) {
+                sb.append("Stack trace:");
+                sb.append(Console.newline());
+                for (StackTraceElement el : parseError.stackTraceElements()) {
+                    sb.append("    ").append(el).append(Console.newline());
+                }
+            }
+        }
+        return sb.toString();
+    }
+
+    private static void printPosition(StringBuilder sb, Range range, String[] lines) {
+        final Pos start = range.start();
+        final int linesCount = lines.length;;
+        if (range.isOnSameLine()) {
+            if (start.row() < linesCount) {
+                sb.append(lines[start.row()]);
+                sb.append(Console.newline());
+                sb.append(" ".repeat(start.col()));
+                sb.append("^".repeat(range.end().col() - start.col() + 1));
+                sb.append(Console.newline());
+            }
+        } else {
+            if (start.row() < linesCount) {
+                String line = lines[start.row()];
+                sb.append(line);
+                sb.append(Console.newline());
+                sb.append(" ".repeat(start.col()));
+                sb.append("^".repeat(Math.max(1, line.length() - start.col())));
+                sb.append(Console.newline());
+            }
+            final Pos end = range.end();
+            if (end.row() < linesCount) {
+                sb.append(lines[end.row()]);
+                sb.append(Console.newline());
+                sb.append("^".repeat(end.col()));
+                sb.append(Console.newline());
+            }
+        }
+    }
+}