1 files changed, 131 insertions, 0 deletions
diff --git a/packages/server/src/core/logger.ts b/packages/server/src/core/logger.ts
new file mode 100644
index 00000000..d12d4240
--- /dev/null
+++ b/packages/server/src/core/logger.ts
@@ -0,0 +1,131 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import path from 'node:path';
+import sqlite3 from 'sqlite3';
+import { promises as fs } from 'node:fs';
+
+const GEMINI_DIR = '.gemini';
+const DB_NAME = 'logs.db';
+const CREATE_TABLE_SQL = `
+CREATE TABLE IF NOT EXISTS messages (
+    session_id INTEGER,
+    message_id INTEGER,
+    timestamp TEXT,
+    type TEXT,
+    message TEXT
+);`;
+
+export enum MessageSenderType {
+  USER = 'user',
+}
+
+export class Logger {
+  private db: sqlite3.Database | undefined;
+  private sessionId: number | undefined;
+  private messageId: number | undefined;
+
+  constructor() {}
+
+  async initialize(): Promise<void> {
+    if (this.db) {
+      return;
+    }
+
+    this.sessionId = Math.floor(Date.now() / 1000);
+    this.messageId = 0;
+
+    // Could be cleaner if our sqlite package supported promises.
+    return new Promise((resolve, reject) => {
+      const DB_DIR = path.resolve(process.cwd(), GEMINI_DIR);
+      const DB_PATH = path.join(DB_DIR, DB_NAME);
+      fs.mkdir(DB_DIR, { recursive: true })
+        .then(() => {
+          this.db = new sqlite3.Database(
+            DB_PATH,
+            sqlite3.OPEN_READWRITE |
+              sqlite3.OPEN_CREATE |
+              sqlite3.OPEN_FULLMUTEX,
+            (err: Error | null) => {
+              if (err) {
+                reject(err);
+              }
+
+              // Read and execute the SQL script in create_tables.sql
+              this.db?.exec(CREATE_TABLE_SQL, (err: Error | null) => {
+                if (err) {
+                  this.db?.close();
+                  reject(err);
+                }
+                resolve();
+              });
+            },
+          );
+        })
+        .catch(reject);
+    });
+  }
+
+  /**
+   * Get list of previous user inputs sorted most recent first.
+   * @returns list of messages.
+   */
+  async getPreviousUserMessages(): Promise<string[]> {
+    if (!this.db) {
+      console.error('Database not initialized.');
+      return [];
+    }
+
+    return new Promise((resolve, reject) => {
+      // Most recent messages first
+      const query = `SELECT message FROM messages 
+      WHERE type = '${MessageSenderType.USER}'
+      ORDER BY session_id DESC, message_id DESC`;
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      this.db!.all(query, [], (err: Error | null, rows: any[]) => {
+        if (err) {
+          reject(err);
+        } else {
+          resolve(rows.map((row) => row.message));
+        }
+      });
+    });
+  }
+
+  async logMessage(type: MessageSenderType, message: string): Promise<void> {
+    if (!this.db) {
+      console.error('Database not initialized.');
+      return;
+    }
+
+    return new Promise((resolve, reject) => {
+      const query = `INSERT INTO messages (session_id, message_id, type, message, timestamp) VALUES (?, ?, ?, ?, datetime('now'))`;
+      this.messageId = this.messageId! + 1;
+      this.db!.run(
+        query,
+        [this.sessionId || 0, this.messageId - 1, type, message],
+        (err: Error | null) => {
+          if (err) {
+            reject(err);
+          } else {
+            resolve();
+          }
+        },
+      );
+    });
+  }
+
+  close(): void {
+    if (this.db) {
+      this.db.close((err: Error | null) => {
+        if (err) {
+          console.error('Error closing database:', err.message);
+        }
+      });
+      this.db = undefined;
+    }
+  }
+}