From 4ee8a06232070a21e7425a3ab20202ea92d62518 Mon Sep 17 00:00:00 2001
From: Slavasil <subvia@proton.me>
Date: Sun, 23 Mar 2025 22:09:27 +0300
Subject: [PATCH] implement question bank parsing

---
 App/Data/Database.cs | 103 +++++++++++++++++++++++++++++++++++++++++++
 App/Program.cs       |  10 ++++-
 2 files changed, 112 insertions(+), 1 deletion(-)
 create mode 100644 App/Data/Database.cs

diff --git a/App/Data/Database.cs b/App/Data/Database.cs
new file mode 100644
index 0000000..5f50d17
--- /dev/null
+++ b/App/Data/Database.cs
@@ -0,0 +1,103 @@
+namespace Game.Data {
+    public class Database {
+        public List<Question> questions = new List<Question>();
+        public static Database ReadFromFile(string filename) {
+            var db = new Database();
+            using (StreamReader rd = new StreamReader(filename)) {
+                string? line;
+                int lineNumber = 1;
+                while ((line = rd.ReadLine()) != null) {
+                    int i = 0;
+                    int len = line.Length;
+                    int state = 0;
+                    int correctAnswer = -1;
+                    List<string> answers = new List<string>();
+
+                    // read question
+                    while (i < len + 1) {
+                        if (i == len) {
+                            throw new DatabaseReadException(I18n.Message.ERROR_NO_ANSWER_OPTIONS, lineNumber, i);
+                        } else if (line[i] == '|')
+                            if (state == 1) {
+                                ++i;
+                                break;
+                            } else {
+                                state = 1;
+                            }
+                        else state = 0;
+                        ++i;
+                    }
+                    string question = line.Substring(0, i - 2);
+
+                    int currentAnswer = 0;
+                    while (i < len) {
+                        // read answer text
+                        state = 0;
+                        int answerStart = i;
+                        while (i < len + 1) {
+                            if (i == len) {
+                                throw new DatabaseReadException(I18n.Message.ERROR_EXPECTED_ARROW_TOKEN, lineNumber, i);
+                            } else if (state == 0) {
+                                if (line[i] == '=')
+                                    state = 1;
+                            } else if (state == 1) {
+                                if (line[i] == '>') {
+                                    ++i;
+                                    break;
+                                } else {
+                                    state = 0;
+                                }
+                            }
+                            ++i;
+                        }
+                        string answer = line.Substring(answerStart, i - answerStart - 2);
+                        // read True or False
+                        if (line[i] == 'T') {
+                            if (i + 3 < len && line[i + 1] == 'r' && line[i + 2] == 'u' && line[i + 3] == 'e') {
+                                correctAnswer = currentAnswer;
+                                i += 4;
+                            } else {
+                                throw new DatabaseReadException(I18n.Message.ERROR_EXPECTED_TRUE_OR_FALSE, lineNumber, i);
+                            }
+                        } else if (line[i] == 'F') {
+                            if (i + 4 < len && line[i + 1] == 'a' && line[i + 2] == 'l' && line[i + 3] == 's' && line[i + 4] == 'e') {
+                                i += 5;
+                            } else {
+                                throw new DatabaseReadException(I18n.Message.ERROR_EXPECTED_TRUE_OR_FALSE, lineNumber, i);
+                            }
+                        }
+                        // consume separator
+                        if (i + 1 < len && (line[i] != '|' || line[i + 1] != '|'))
+                            throw new DatabaseReadException(I18n.Message.ERROR_EXPECTED_ANSWER_SEPARATOR, lineNumber, i);
+                        i += 2;
+                        answers.Add(answer);
+                        ++currentAnswer;
+                    }
+
+                    lineNumber++;
+                    db.questions.Add(new Question(question, answers, correctAnswer));
+                }
+            }
+            return db;
+        }
+    }
+
+    public class DatabaseReadException : Exception {
+        public readonly int line, column;
+        public readonly I18n.Message messageId;
+
+        public DatabaseReadException(I18n.Message messageId) {
+            this.messageId = messageId;
+            line = -1;
+            column = -1;
+        }
+
+        public DatabaseReadException(I18n.Message messageId, int line, int column) {
+            this.messageId = messageId;
+            this.line = line;
+            this.column = column;
+        }
+    }
+
+    public record Question (string question, List<string> answers, int correctAnswer);
+}
\ No newline at end of file
diff --git a/App/Program.cs b/App/Program.cs
index 4dd9c2e..9f7c6ee 100644
--- a/App/Program.cs
+++ b/App/Program.cs
@@ -29,7 +29,15 @@ namespace Game {
                 return 2;
             }
 
-            string databaseFileName = opts.databaseFilename ?? gameConfig.databasePath;
+            string databaseFileName = opts.databaseFilename ?? gameConfig.databasePath;
+            Database questionDatabase;
+            try {
+                questionDatabase = Database.ReadFromFile(databaseFileName);
+            } catch (DatabaseReadException e) {
+                display.ShowFatalError(string.Format(I18n.GetMessage(I18n.Message.SYNTAX_ERROR), I18n.GetMessage(e.messageId), e.line.ToString(), e.column.ToString()));
+                Console.ReadKey();
+                return 3;
+            }
 
             display.ResetWindow();