commit 6882c6a8cdab23865a10040ec2fde7d0f4cd6b55
Author: Peisong Xiao <peisong.xiao.xps@gmail.com>
Date:   Thu Sep 25 20:12:38 2025 -0400

    inital commit: added app.py for a simple hello world to the database

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..d2fac75
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.venv/**/*
\ No newline at end of file
diff --git a/app.py b/app.py
new file mode 100755
index 0000000..3a97f6b
--- /dev/null
+++ b/app.py
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+#!/usr/bin/env python3
+
+import os
+import sys
+import mysql.connector
+from mysql.connector import errorcode
+
+CFG = {
+    "host": os.getenv("DB_HOST", "127.0.0.1"),
+    "user": os.getenv("DB_USER", "cs348"),
+    "password": os.getenv("DB_PASS", "Cs348Group!"),
+    "database": os.getenv("DB_NAME", "cs348db"),
+    "charset": "utf8mb4",
+    "collation": "utf8mb4_unicode_ci",
+    "auth_plugin": "caching_sha2_password",
+}
+
+DDL = """
+CREATE TABLE IF NOT EXISTS `ChatHistory` (
+  `text_id` INT NOT NULL,
+  `type`    VARCHAR(64) NOT NULL,
+  `text`    MEDIUMTEXT NOT NULL,
+  PRIMARY KEY (`text_id`)
+) ENGINE=InnoDB
+  DEFAULT CHARSET = utf8mb4
+  COLLATE = utf8mb4_unicode_ci;
+"""
+
+def get_connection():
+    try:
+        return mysql.connector.connect(**CFG)
+    except mysql.connector.Error as e:
+        print(f"[fatal] MySQL connect error: {e}", file=sys.stderr)
+        sys.exit(1)
+
+def ensure_table(conn):
+    with conn.cursor() as cur:
+        cur.execute(DDL)
+    conn.commit()
+
+def get_next_id(conn):
+    with conn.cursor() as cur:
+        cur.execute("SELECT COALESCE(MAX(text_id), 0) FROM `ChatHistory`;")
+        (max_id,) = cur.fetchone()
+    return int(max_id) + 1
+
+def insert_two_rows(conn, user_text: str):
+    nxt = get_next_id(conn)
+    rows = [
+        (nxt,     "user",      user_text),
+        (nxt + 1, "assistant", "LLM answer here"),
+    ]
+    with conn.cursor() as cur:
+        cur.executemany(
+            "INSERT INTO `ChatHistory` (`text_id`, `type`, `text`) VALUES (%s, %s, %s);",
+            rows,
+        )
+    conn.commit()
+    return nxt, nxt + 1
+
+def list_history(conn, limit: int | None = None):
+    sql = "SELECT `text_id`, `type`, `text` FROM `ChatHistory` ORDER BY `text_id` ASC"
+    params = ()
+    if limit is not None and limit > 0:
+        sql += " LIMIT %s"
+        params = (limit,)
+    with conn.cursor() as cur:
+        cur.execute(sql, params)
+        rows = cur.fetchall()
+    if not rows:
+        print("(no rows)")
+        return
+    # Simple pretty print without extra deps
+    idw = max(len("text_id"), *(len(str(r[0])) for r in rows))
+    typew = max(len("type"), *(len(str(r[1])) for r in rows))
+    print(f"{'text_id'.ljust(idw)}  {'type'.ljust(typew)}  text")
+    print(f"{'-'*idw}  {'-'*typew}  {'-'*4}")
+    for tid, typ, txt in rows:
+        print(f"{str(tid).ljust(idw)}  {str(typ).ljust(typew)}  {txt}")
+
+def print_help():
+    print(r"""
+Commands:
+  \list            Print all history (ordered by text_id)
+  \list N          Print first N rows (ordered by text_id)
+  \q               Quit
+  \help            This help
+
+Anything else is sent as a user prompt:
+  - Inserts (next_id,   'user',      <your text>)
+  - Inserts (next_id+1, 'assistant', 'LLM answer here')
+""".strip())
+
+def main():
+    print("Connecting to MySQL…")
+    conn = get_connection()
+    try:
+        ensure_table(conn)
+        print("Ready. Type \\help for commands. Empty line quits.")
+        while True:
+            try:
+                line = input("Enter prompt> ")
+            except (EOFError, KeyboardInterrupt):
+                print("\nBye.")
+                break
+
+            if line is None:
+                continue
+            line = line.strip()
+            if not line:
+                print("Bye.")
+                break
+
+            # Commands
+            if line == r"\q":
+                print("Bye.")
+                break
+            if line == r"\help":
+                print_help()
+                continue
+            if line.startswith(r"\list"):
+                parts = line.split()
+                limit = None
+                if len(parts) == 2 and parts[1].isdigit():
+                    limit = int(parts[1])
+                try:
+                    list_history(conn, limit)
+                except mysql.connector.Error as e:
+                    print(f"[error] list failed: {e}", file=sys.stderr)
+                continue
+
+            # Regular insert path
+            try:
+                first_id, second_id = insert_two_rows(conn, line)
+                print(f"Inserted prompt at text_id={first_id} and placeholder at text_id={second_id}.")
+            except mysql.connector.Error as e:
+                print(f"[error] insert failed: {e}", file=sys.stderr)
+                if e.errno in (errorcode.CR_SERVER_GONE_ERROR, errorcode.CR_SERVER_LOST):
+                    try:
+                        conn.close()
+                    except Exception:
+                        pass
+                    conn = get_connection()
+    finally:
+        try:
+            conn.close()
+        except Exception:
+            pass
+
+if __name__ == "__main__":
+    main()