GPT : Timezone and reporting improvements

Add timezone-aware timestamp support and reporting improvements
Store timestamps in ISO-8601 format with timezone offsets
Accept client-local timestamps from browser and API
Normalize legacy naive timestamps during parsing
Add migration script for converting old SQLite timestamps
Fix mixed naive/aware datetime comparison errors
Render timestamps in browser-local timezone
Auto-generate default 7-day reports on page load
Expand default dashboard report to include all users
Preserve manual single-user report generation
Add curl-based validation/test script for API and report flows

app.py

@@ -2,27 +2,20 @@
 
 """
 Minimal Time Clock Application
-
-Requirements:
-- Python 3
-- Flask
-- sqlite3
-- Linux compatible
-- No JavaScript
-- Simple HTML UI
-
-Features:
-- User selection
-- Clock in
-- Clock out
-- Report generation
-- CRUD API
-- Automatic database initialization
 """
 
 import sqlite3
-from datetime import datetime, timedelta
+
-from flask import Flask, request, redirect, url_for, render_template, jsonify
+from datetime import datetime, timedelta, timezone
+
+LEGACY_TIMEZONE = timezone.utc
+
+from flask import (
+    Flask,
+    request,
+    render_template,
+    jsonify
+)
 
 # -----------------------------------------------------------------------------
 # Flask Configuration
@@ -40,8 +33,10 @@ def get_db_connection():
     """
     Create and return a sqlite3 database connection.
     """
+
     conn = sqlite3.connect(DATABASE)
     conn.row_factory = sqlite3.Row
+
     return conn
 
 
@@ -51,9 +46,9 @@ def initialize_database():
     """
 
     conn = get_db_connection()
+
     cursor = conn.cursor()
 
-    # Users table
     cursor.execute("""
         CREATE TABLE IF NOT EXISTS users (
             id INTEGER PRIMARY KEY AUTOINCREMENT,
@@ -61,113 +56,146 @@ def initialize_database():
         )
     """)
 
-    # Entries table
-    #
-    # user_id:
-    #   References users.id
-    #
-    # entrytype:
-    #   Must be either 'in' or 'out'
-    #
-    # ts:
-    #   Timestamp stored as ISO datetime string
-    #
     cursor.execute("""
         CREATE TABLE IF NOT EXISTS entries (
             id INTEGER PRIMARY KEY AUTOINCREMENT,
             user_id INTEGER NOT NULL,
             entrytype TEXT NOT NULL CHECK(entrytype IN ('in', 'out')),
-            ts DATETIME NOT NULL,
+            ts TEXT NOT NULL,
             FOREIGN KEY(user_id) REFERENCES users(id)
         )
     """)
 
     conn.commit()
 
-    # Add sample users if table is empty
     cursor.execute("SELECT COUNT(*) AS count FROM users")
+
     result = cursor.fetchone()
 
     if result["count"] == 0:
         cursor.execute("INSERT INTO users (name) VALUES ('Alice')")
         cursor.execute("INSERT INTO users (name) VALUES ('Bob')")
         cursor.execute("INSERT INTO users (name) VALUES ('Charlie')")
+
         conn.commit()
 
     conn.close()
 
+# -----------------------------------------------------------------------------
+# Time Helpers
+# -----------------------------------------------------------------------------
+
+def parse_iso_datetime(value):
+    """
+    Parse timestamps into timezone-aware datetime objects.
+
+    Handles both:
+        2026-05-29 08:00:00
+    and:
+        2026-05-29T08:00:00-04:00
+    """
+
+    #
+    # Support legacy sqlite format:
+    #   2026-05-29 08:00:00
+    #
+
+    normalized = value.replace(" ", "T")
+
+    dt = datetime.fromisoformat(normalized)
+
+    #
+    # If timestamp is naive, assume legacy timezone.
+    #
+
+    if dt.tzinfo is None:
+        dt = dt.replace(tzinfo=LEGACY_TIMEZONE)
+
+    return dt
+
+def utc_now():
+    """
+    Return current UTC timestamp.
+    """
+
+    return datetime.now(timezone.utc)
+
+
 # -----------------------------------------------------------------------------
 # Utility Functions
 # -----------------------------------------------------------------------------
 
-def create_entry(user_id, entry_type):
+def create_entry(user_id, entry_type, client_timestamp=None):
     """
     Create a clock in/out entry for the specified user.
     """
 
     conn = get_db_connection()
+
     cursor = conn.cursor()
 
-    timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+    if client_timestamp:
+        timestamp = parse_iso_datetime(client_timestamp)
+    else:
+        timestamp = utc_now()
 
     cursor.execute("""
         INSERT INTO entries (user_id, entrytype, ts)
         VALUES (?, ?, ?)
-    """, (user_id, entry_type, timestamp))
+    """, (
+        user_id,
+        entry_type,
+        timestamp.isoformat()
+    ))
 
     conn.commit()
+
     conn.close()
 
 
 def generate_report(user_id, begin_date, end_date):
     """
     Generate total worked hours for a user between two dates.
-
-    Assumptions:
-    - Entries alternate correctly between 'in' and 'out'
-    - Missing pairs are ignored
     """
 
     conn = get_db_connection()
+
     cursor = conn.cursor()
 
-    # Inclusive date range
+    begin_dt = parse_iso_datetime(begin_date)
-    begin_dt = datetime.strptime(begin_date, "%Y-%m-%dT%H:%M")
+    end_dt = parse_iso_datetime(end_date)
-    end_dt = datetime.strptime(end_date, "%Y-%m-%dT%H:%M")
-
-    # Include entire ending day
-    end_dt = end_dt + timedelta(days=1)
 
     cursor.execute("""
         SELECT entrytype, ts
         FROM entries
         WHERE user_id = ?
-          AND ts >= ?
-          AND ts < ?
         ORDER BY ts ASC
-    """, (
+    """, (user_id,))
-        user_id,
-        begin_dt.strftime("%Y-%m-%d %H:%M"),
-        end_dt.strftime("%Y-%m-%d %H:%M")
-    ))
 
     rows = cursor.fetchall()
 
     conn.close()
 
     total_seconds = 0
+
     clock_in_time = None
 
     for row in rows:
-        entry_type = row["entrytype"]
-        timestamp = datetime.strptime(row["ts"], "%Y-%m-%d %H:%M:%S")
 
-        if entry_type == "in":
+        timestamp = parse_iso_datetime(row["ts"])
+
+        if timestamp < begin_dt or timestamp > end_dt:
+            continue
+
+        if row["entrytype"] == "in":
             clock_in_time = timestamp
 
-        elif entry_type == "out" and clock_in_time is not None:
+        elif row["entrytype"] == "out" and clock_in_time is not None:
+
             delta = timestamp - clock_in_time
+
             total_seconds += delta.total_seconds()
+
             clock_in_time = None
 
     total_hours = total_seconds / 3600.0
@@ -192,10 +220,8 @@ def index():
         ORDER BY name
     """).fetchall()
 
-
-    # NEW: users currently clocked in
     clocked_in_users = conn.execute("""
-        SELECT u.id, u.name
+        SELECT u.id, u.name, last_entry.ts
         FROM users u
         JOIN (
             SELECT e.user_id, e.entrytype, e.ts
@@ -206,7 +232,7 @@ def index():
                 GROUP BY user_id
             ) latest
             ON e.user_id = latest.user_id
-               AND e.ts = latest.max_ts
+            AND e.ts = latest.max_ts
         ) last_entry
         ON u.id = last_entry.user_id
         WHERE last_entry.entrytype = 'in'
@@ -215,35 +241,100 @@ def index():
 
     conn.close()
 
+    clocked_in_list = []
+
+    for user in clocked_in_users:
+
+        ts = parse_iso_datetime(user["ts"])
+
+        clocked_in_list.append({
+            "id": user["id"],
+            "name": user["name"],
+            "since": ts.isoformat()
+        })
+
     report_hours = None
 
+    all_user_reports = []
+
+    selected_user_id = None
+
+    now = utc_now()
+
+    default_begin = now - timedelta(days=7)
+
+    default_end = now
+
     if request.method == "POST":
 
-        user_id = request.form.get("user_id")
+        selected_user_id = request.form.get("user_id")
+
         action = request.form.get("action")
 
+        client_timestamp = request.form.get("client_timestamp")
+
         if action == "clock_in":
-            create_entry(user_id, "in")
+
+            create_entry(
+                selected_user_id,
+                "in",
+                client_timestamp
+            )
 
         elif action == "clock_out":
-            create_entry(user_id, "out")
+
+            create_entry(
+                selected_user_id,
+                "out",
+                client_timestamp
+            )
 
         elif action == "report":
 
             begin_date = request.form.get("begin_date")
+
             end_date = request.form.get("end_date")
 
             report_hours = generate_report(
-                user_id,
+                selected_user_id,
                 begin_date,
                 end_date
             )
 
+            default_begin = parse_iso_datetime(begin_date)
+
+            default_end = parse_iso_datetime(end_date)
+
+    else:
+
+        #
+        # Automatically generate last 7 day report
+        # for ALL users
+        #
+
+        for user in users:
+
+            hours = generate_report(
+                user["id"],
+                default_begin.isoformat(),
+                default_end.isoformat()
+            )
+
+            all_user_reports.append({
+                "id": user["id"],
+                "name": user["name"],
+                "hours": hours
+            })
+
     return render_template(
         "index.html",
         users=users,
         report_hours=report_hours,
-        clocked_in_users=clocked_in_users
+        all_user_reports=all_user_reports,
+        clocked_in_users=clocked_in_list,
+        default_begin=default_begin.isoformat(timespec="minutes"),
+        default_end=default_end.isoformat(timespec="minutes"),
+        selected_user_id=selected_user_id
     )
 
 # -----------------------------------------------------------------------------
@@ -252,9 +343,6 @@ def index():
 
 @app.route("/api/users", methods=["GET"])
 def api_get_users():
-    """
-    Return all users.
-    """
 
     conn = get_db_connection()
 
@@ -270,9 +358,6 @@ def api_get_users():
 
 @app.route("/api/entries", methods=["GET"])
 def api_get_entries():
-    """
-    Return all entries.
-    """
 
     conn = get_db_connection()
 
@@ -289,21 +374,30 @@ def api_get_entries():
 
 @app.route("/api/entries", methods=["POST"])
 def api_create_entry():
-    """
-    Create a clock entry.
-    """
 
     data = request.get_json()
 
     user_id = data.get("user_id")
+
     entry_type = data.get("entrytype")
 
+    client_timestamp = data.get("timestamp")
+
     if entry_type not in ("in", "out"):
-        return jsonify({"error": "Invalid entrytype"}), 400
 
-    create_entry(user_id, entry_type)
+        return jsonify({
+            "error": "Invalid entrytype"
+        }), 400
 
-    return jsonify({"status": "success"}), 201
+    create_entry(
+        user_id,
+        entry_type,
+        client_timestamp
+    )
+
+    return jsonify({
+        "status": "success"
+    }), 201
 
 # -----------------------------------------------------------------------------
 # Application Entry Point

migrate_db.sh

@@ -0,0 +1,99 @@
+#!/usr/bin/env bash
+
+#
+# SQLite Timestamp Migration
+#
+# Converts legacy naive timestamps:
+#
+#   2026-05-29 08:15:00
+#
+# into timezone-aware ISO-8601 timestamps:
+#
+#   2026-05-29T08:15:00-04:00
+#
+# Existing timezone-aware timestamps are preserved.
+#
+
+set -euo pipefail
+
+DATABASE="${1:-database/timeclock.db}"
+
+#
+# Timezone offset to apply to old naive timestamps.
+#
+# Examples:
+#   -04:00   Eastern Daylight Time
+#   -05:00   Eastern Standard Time
+#   +00:00   UTC
+#
+DEFAULT_OFFSET="-04:00"
+
+echo "========================================="
+echo "Timeclock Timestamp Migration"
+echo "========================================="
+echo
+echo "Database: ${DATABASE}"
+echo "Assumed legacy offset: ${DEFAULT_OFFSET}"
+echo
+
+if [ ! -f "${DATABASE}" ]; then
+    echo "ERROR: Database not found"
+    exit 1
+fi
+
+BACKUP="${DATABASE}.backup.$(date +%Y%m%d%H%M%S)"
+
+echo "Creating backup:"
+echo "  ${BACKUP}"
+
+cp "${DATABASE}" "${BACKUP}"
+
+echo
+echo "Beginning migration..."
+echo
+
+sqlite3 "${DATABASE}" <<SQL
+BEGIN TRANSACTION;
+
+--
+-- Convert naive timestamps to ISO8601 with timezone
+--
+-- Only modify timestamps that:
+--   1. Do NOT already contain timezone offsets
+--   2. Do NOT already contain a trailing Z
+--
+
+UPDATE entries
+SET ts =
+    REPLACE(ts, ' ', 'T') || '${DEFAULT_OFFSET}'
+WHERE
+    ts NOT LIKE '%+__:__'
+    AND ts NOT LIKE '%-__:__'
+    AND ts NOT LIKE '%Z';
+
+COMMIT;
+SQL
+
+echo
+echo "Migration complete."
+echo
+
+echo "Verifying results..."
+echo
+
+sqlite3 "${DATABASE}" <<SQL
+.headers on
+.mode column
+
+SELECT
+    id,
+    user_id,
+    entrytype,
+    ts
+FROM entries
+ORDER BY id DESC
+LIMIT 10;
+SQL
+
+echo
+echo "Done."

templates/index.html

@@ -1,5 +1,6 @@
 <!DOCTYPE html>
 <html>
+
 <head>
     <title>Time Clock</title>
 </head>
@@ -13,7 +14,13 @@
 {% if clocked_in_users %}
     <ul>
         {% for user in clocked_in_users %}
-            <li>{{ user.name }}</li>
+            <li>
+                {{ user.name }} —
+                since
+                <span class="tztime" data-ts="{{ user.since }}">
+                    {{ user.since }}
+                </span>
+            </li>
         {% endfor %}
     </ul>
 {% else %}
@@ -21,21 +28,58 @@
 {% endif %}
 
 <br/>
+
+{% if all_user_reports %}
+
+<h2>Last 7 Days Report</h2>
+
+<table border="1" cellpadding="5">
+
+<tr>
+    <th>User</th>
+    <th>Total Hours Worked</th>
+</tr>
+
+{% for report in all_user_reports %}
+<tr>
+    <td>{{ report.name }}</td>
+    <td>{{ report.hours }}</td>
+</tr>
+{% endfor %}
+
+</table>
+
+<br>
+
+{% endif %}
+
 <hr/>
 <br/>
 
-<form method="POST">
+<form method="POST" id="timeclock-form">
+
+<input
+    type="hidden"
+    name="client_timestamp"
+    id="client_timestamp"
+>
 
 <table border="1" cellpadding="5">
 
 <tr>
     <td>User</td>
+
     <td>
         <select name="user_id">
 
         {% for user in users %}
-            <option value="{{ user.id }}">
+            <option
-              {{ user.name }}
+                value="{{ user.id }}"
+                {% if selected_user_id == user.id %}
+                    selected
+                {% endif %}
+            >
+                {{ user.name }}
             </option>
         {% endfor %}
 
@@ -47,13 +91,25 @@
     <td>Clock Actions</td>
 
     <td>
-        <button type="submit" name="action" value="clock_in">
+
+        <button
+            type="submit"
+            name="action"
+            value="clock_in"
+            onclick="setCurrentTimestamp()"
+        >
             Clock In
         </button>
 
-        <button type="submit" name="action" value="clock_out">
+        <button
+            type="submit"
+            name="action"
+            value="clock_out"
+            onclick="setCurrentTimestamp()"
+        >
             Clock Out
         </button>
+
     </td>
 </tr>
 
@@ -64,6 +120,7 @@
         <input
             type="datetime-local"
             name="begin_date"
+            id="begin_date"
             value=""
         >
     </td>
@@ -76,6 +133,7 @@
         <input
             type="datetime-local"
             name="end_date"
+            id="end_date"
             value=""
         >
     </td>
@@ -85,7 +143,11 @@
     <td>Report</td>
 
     <td>
-        <button type="submit" name="action" value="report">
+        <button
+            type="submit"
+            name="action"
+            value="report"
+        >
             Generate Report
         </button>
     </td>
@@ -99,6 +161,8 @@
 
 {% if report_hours is not none %}
 
+<h2>Custom Report</h2>
+
 <table border="1" cellpadding="5">
 
 <tr>
@@ -113,5 +177,60 @@
 
 {% endif %}
 
+<script>
+
+function localDatetimeValue(date) {
+
+    const pad = (v) => String(v).padStart(2, "0");
+
+    return (
+        date.getFullYear() + "-" +
+        pad(date.getMonth() + 1) + "-" +
+        pad(date.getDate()) + "T" +
+        pad(date.getHours()) + ":" +
+        pad(date.getMinutes())
+    );
+}
+
+function setCurrentTimestamp() {
+
+    document.getElementById("client_timestamp").value =
+        new Date().toISOString();
+}
+
+window.addEventListener("load", () => {
+
+    //
+    // Populate default report range
+    //
+
+    const now = new Date();
+
+    const weekAgo = new Date();
+
+    weekAgo.setDate(now.getDate() - 7);
+
+    document.getElementById("begin_date").value =
+        localDatetimeValue(weekAgo);
+
+    document.getElementById("end_date").value =
+        localDatetimeValue(now);
+
+    //
+    // Convert displayed timestamps to local timezone
+    //
+
+    document.querySelectorAll(".tztime").forEach((el) => {
+
+        const ts = el.dataset.ts;
+
+        const d = new Date(ts);
+
+        el.textContent = d.toLocaleString();
+    });
+});
+
+</script>
+
 </body>
 </html>

test.sh

@@ -0,0 +1,77 @@
+#!/usr/bin/env bash
+
+set -e
+
+BASE_URL="http://127.0.0.1:5000"
+
+echo "======================================="
+echo "Fetching users"
+echo "======================================="
+
+curl -s \
+    "${BASE_URL}/api/users" \
+    | jq .
+
+echo
+echo "======================================="
+echo "Clocking IN user 1"
+echo "======================================="
+
+curl -s \
+    -X POST \
+    -H "Content-Type: application/json" \
+    -d '{
+        "user_id": 1,
+        "entrytype": "in",
+        "timestamp": "2026-05-29T08:00:00-04:00"
+    }' \
+    "${BASE_URL}/api/entries" \
+    | jq .
+
+sleep 1
+
+echo
+echo "======================================="
+echo "Clocking OUT user 1"
+echo "======================================="
+
+curl -s \
+    -X POST \
+    -H "Content-Type: application/json" \
+    -d '{
+        "user_id": 1,
+        "entrytype": "out",
+        "timestamp": "2026-05-29T17:00:00-04:00"
+    }' \
+    "${BASE_URL}/api/entries" \
+    | jq .
+
+echo
+echo "======================================="
+echo "Fetching entries"
+echo "======================================="
+
+curl -s \
+    "${BASE_URL}/api/entries" \
+    | jq .
+
+echo
+echo "======================================="
+echo "Generating report through web form"
+echo "======================================="
+
+curl -s \
+    -X POST \
+    -d "user_id=1" \
+    -d "action=report" \
+    -d "begin_date=2026-05-22T00:00:00-04:00" \
+    -d "end_date=2026-05-29T23:59:59-04:00" \
+    "${BASE_URL}/" \
+    > report.html
+
+echo "Report saved to report.html"
+
+echo
+echo "======================================="
+echo "Done"
+echo "======================================="