First attempt at a postgres times script handles start/end time and limit

mapserver/cgi-bin/layer_times_postgres.py

@@ -3,37 +3,94 @@ import os
 import sys
 import cgi
 import json
+from datetime import datetime
 import psycopg2
 from psycopg2 import sql
 
-pw_filename = "__POSTGRES_PASSWORD_FILE__"
-connect_str = "host=__POSTGRES_HOST__ " \
-              "port=__POSTGRES_PORT__ " \
-              "dbname=__POSTGRES_DBNAME__ " \
-              "user=__POSTGRES_USER__"
-if not os.path.isfile(pw_filename) or '__' in connect_str:
-    print("""Status: 500 Backend Misconfigured\n
+
+def bad_request(msg):
+    print("""Status: 400 Bad Request
+Content-type: text/plain
+Access-Control-Allow-Origin: *
+
+{}""".format(msg))
+    sys.exit(1)
+
+
+def get_connect_str():
+    pw_filename = "__POSTGRES_PASSWORD_FILE__"
+    connect_str = "host=__POSTGRES_HOST__ " \
+                  "port=__POSTGRES_PORT__ " \
+                  "dbname=__POSTGRES_DBNAME__ " \
+                  "user=__POSTGRES_USER__"
+    if not os.path.isfile(pw_filename) or '__' in connect_str:
+        print("""Status: 500 Backend Misconfigured\n
 Content-type: text/plain
 Access-Control-Allow-Origin: *
 
 Backend has not been configured properly and doesn't know how to communicate with the database.
 Please contact site administrator.
-""")
-    sys.exit(1)
+    """)
+        sys.exit(1)
 
-with open(pw_filename, 'r') as pw_file:
-    password = pw_file.read().strip()
-    connect_str += " password={}".format(password)
+    with open(pw_filename, 'r') as pw_file:
+        password = pw_file.read().strip()
+        connect_str += " password={}".format(password)
+    return connect_str
 
 
+connect_str = get_connect_str()
 form = cgi.FieldStorage()
-table_name = form['layer'].value
+table_name = form.getvalue('layer')
+start_time = form.getvalue('start_time')
+end_time = form.getvalue('end_time')
+num_times = form.getvalue('num_times', 0)
+order = form.getvalue('order', 'ASC')
+
+if table_name is None:
+    bad_request("Missing required parameter 'layer'.")
+
+if start_time is not None:
+    try:
+        start_time = datetime.strptime(start_time, "%Y-%m-%dT%H:%M:%S")
+    except ValueError:
+        bad_request("""Bad 'start_time' format. Expected: 'YYYY-MM-DDTHH:MM:SS'""")
+
+if end_time is not None:
+    try:
+        end_time = datetime.strptime(end_time, "%Y-%m-%dT%H:%M:%S")
+    except ValueError:
+        bad_request("""Bad 'end_time' format. Expected: 'YYYY-MM-DDTHH:MM:SS'""")
+
+try:
+    num_times = int(num_times)
+    if num_times < 0:
+        raise ValueError("'num_times' must greater or equal to 0.")
+except ValueError:
+    bad_request("""Invalid integer for 'num_times'.""")
+
+order = order.upper()
+if order not in ('ASC', 'DESC'):
+    bad_request("""'order' must be either 'ASC' or 'DESC'.""")
+
+query_str = "SELECT start_time FROM {}"
+if start_time is not None or end_time is not None:
+    query_str += " WHERE "
+if start_time is not None:
+    query_str += "start_time >= {}".format(start_time.strftime('%Y-%m-%dT%H:%M:%S'))
+if start_time is not None and end_time is not None:
+    query_str += " AND "
+if end_time is not None:
+    query_str += "start_time <= {}".format(end_time.strftime('%Y-%m-%dT%H:%M:%S'))
+query_str += " ORDER BY start_time {}".format(order)
+if num_times != 0:
+    query_str += " LIMIT {}".format(num_times)
 
 try:
     conn = psycopg2.connect(connect_str)
     with conn:
         with conn.cursor() as cur:
-            cur.execute(sql.SQL("SELECT start_time FROM {} ORDER BY start_time").format(sql.Identifier(table_name)))
+            cur.execute(sql.SQL(query_str).format(sql.Identifier(table_name)))
             times = cur.fetchall()
 except psycopg2.errors.DataBaseError:
     print("""Status: 500 Database Error