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Improve/refactor income and ledger scripts with plomlib.
authorChristian Heller <c.heller@plomlompom.de>
Sun, 19 Nov 2023 01:06:55 +0000 (02:06 +0100)
committerChristian Heller <c.heller@plomlompom.de>
Sun, 19 Nov 2023 01:06:55 +0000 (02:06 +0100)
income_progress_bars.py
ledger.py
plomlib.py [new file with mode: 0644]

index 3edb48dc75068267e00900759587d79542d59076..94a34569c70909a290c82ad21eb6bba8cf8a6196 100644 (file)
@@ -1,10 +1,10 @@
-from http.server import BaseHTTPRequestHandler, HTTPServer
+from http.server import BaseHTTPRequestHandler, HTTPServer
 import os
 import json
 import jinja2
 import os
 import json
 import jinja2
+from plomlib import PlomDB, PlomException, run_server, run_server, PlomServer
 
 
-hostName = "localhost"
-serverPort = 8081
+server_port = 8081
 
 tmpl = jinja2.Template("""<html>
 <meta charset="UTF-8">
 
 tmpl = jinja2.Template("""<html>
 <meta charset="UTF-8">
@@ -106,42 +106,32 @@ table {
 </body
 </html>""")
 
 </body
 </html>""")
 
-class Database:
-    timestamp_year = 0,
-    timestamp_month = 0,
-    timestamp_week = 0,
-    year_income = 0,
-    month_income = 0,
-    week_income = 0,
-    workday_hourly_rate_1 = 10,
-    workday_hourly_rate_2 = 25,
-    workday_hourly_rate_3 = 50,
-    workday_minutes_worked_1 = 0,
-    workday_minutes_worked_2 = 0,
-    workday_minutes_worked_3 = 0,
-    year_goal = 20000,
-    workdays_per_month = 16
+class IncomeDB(PlomDB):
 
     def __init__(self):
 
     def __init__(self):
-        db_name = "_income"
-        self.db_file = db_name + ".json"
-        self.lock_file = db_name+ ".lock"
-        if os.path.exists(self.db_file):
-            with open(self.db_file, "r") as f:
-                d = json.load(f)
-                for k, v in d.items():
-                    if not hasattr(self, k):
-                        raise Exception("bad key in db: " + k)
-                    setattr(self, k, v)
+        # defaults
+        self.timestamp_year = 0,
+        self.timestamp_month = 0,
+        self.timestamp_week = 0,
+        self.year_income = 0,
+        self.month_income = 0,
+        self.week_income = 0,
+        self.workday_hourly_rate_1 = 10,
+        self.workday_hourly_rate_2 = 25,
+        self.workday_hourly_rate_3 = 50,
+        self.workday_minutes_worked_1 = 0,
+        self.workday_minutes_worked_2 = 0,
+        self.workday_minutes_worked_3 = 0,
+        self.year_goal = 20000,
+        self.workdays_per_month = 16
+        super().__init__('_income')
 
 
-    def lock(self):
-        if os.path.exists(self.lock_file):
-            raise Exception('Sorry, lock file!')
-        f = open(self.lock_file, 'w+')
-        f.close()
-
-    def unlock(self):
-        os.remove(self.lock_file)
+    def read_db_file(self, f):
+        d = json.load(f)
+        for k, v in d.items():
+            if not hasattr(self, k):
+                raise PlomException("bad key in db: " + k)
+            setattr(self, k, v)
 
     def to_dict(self):
         keys = [k for k in dir(self) if (not k.startswith('_')) and (not callable(getattr(self, k)))]
 
     def to_dict(self):
         keys = [k for k in dir(self) if (not k.startswith('_')) and (not callable(getattr(self, k)))]
@@ -153,58 +143,6 @@ class Database:
     def write_db(self):
         self.write_text_to_db(json.dumps(self.to_dict()))
 
     def write_db(self):
         self.write_text_to_db(json.dumps(self.to_dict()))
 
-    def backup(self):
-        import shutil
-        from datetime import datetime, timedelta
-        # collect modification times of numbered .bak files
-        bak_prefix = f'{self.db_file}.bak.'
-        backup_dates = []
-        i = 0
-        bak_as = f'{bak_prefix}{i}'
-        while os.path.exists(bak_as):
-            mod_time = os.path.getmtime(bak_as)
-            backup_dates += [str(datetime.fromtimestamp(mod_time))]
-            i += 1
-            bak_as = f'{bak_prefix}{i}'
-
-        # collect what numbered .bak files to save: the older, the fewer; for each
-        # timedelta, keep the newest file that's older
-        ages_to_keep = [timedelta(minutes=4**i) for i in range(0, 8)]
-        now = datetime.now() 
-        to_save = []
-        for age in ages_to_keep:
-            limit = now - age 
-            for i, date in enumerate(reversed(backup_dates)):
-                if datetime.strptime(date, '%Y-%m-%d %H:%M:%S.%f') < limit:
-                    unreversed_i = len(backup_dates) - i - 1
-                    if unreversed_i not in to_save:
-                        to_save += [unreversed_i]
-                    break
-
-        # remove redundant backup files 
-        j = 0
-        for i in to_save:
-            if i != j:
-                source = f'{bak_prefix}{i}'
-                target = f'{bak_prefix}{j}'
-                shutil.move(source, target)
-            j += 1
-        for i in range(j, len(backup_dates)):
-            try:
-                os.remove(f'{bak_prefix}{i}')
-            except FileNotFoundError:
-                pass
-
-        # put copy of current state at end of bak list 
-        shutil.copy(self.db_file, f'{bak_prefix}{j}')
-
-    def write_text_to_db(self, text):
-        self.lock()
-        self.backup()
-        with open(self.db_file, 'w') as f:
-            f.write(text);
-        self.unlock()
-
 class ProgressBar:
     def __init__(self, title, earned, goal, time_progress=-1):
         self.title = title
 class ProgressBar:
     def __init__(self, title, earned, goal, time_progress=-1):
         self.title = title
@@ -222,112 +160,101 @@ class ProgressBar:
             if time_progress > 0:
                 self.success = success_income / time_progress
 
             if time_progress > 0:
                 self.success = success_income / time_progress
 
-class MyServer(BaseHTTPRequestHandler):
+# class MyServer(BaseHTTPRequestHandler):
+class IncomeServer(PlomServer):
 
     def do_POST(self):
         from urllib.parse import parse_qs
 
     def do_POST(self):
         from urllib.parse import parse_qs
-        length = int(self.headers['content-length'])
-        postvars = parse_qs(self.rfile.read(length).decode(), keep_blank_values=1)
-        db = Database()
-        db.workday_minutes_worked_1 = int(postvars['workday_minutes_worked_1'][0])
-        db.workday_minutes_worked_2 = int(postvars['workday_minutes_worked_2'][0])
-        db.workday_minutes_worked_3 = int(postvars['workday_minutes_worked_3'][0])
-        db.workday_hourly_rate_1 = int(postvars['workday_hourly_rate_1'][0])
-        db.workday_hourly_rate_2 = int(postvars['workday_hourly_rate_2'][0])
-        db.workday_hourly_rate_3 = int(postvars['workday_hourly_rate_3'][0])
-        db.year_goal = int(postvars['year_goal'][0])
-        db.workdays_per_month = int(postvars['workdays_per_month'][0])
-        if 'finish' in postvars.keys():
-            day_income = (db.workday_minutes_worked_1 / 60.0) * db.workday_hourly_rate_1
-            day_income += (db.workday_minutes_worked_2 / 60.0) * db.workday_hourly_rate_2
-            day_income += (db.workday_minutes_worked_3 / 60.0) * db.workday_hourly_rate_3
-            db.year_income += day_income
-            db.month_income += day_income
-            db.week_income += day_income
-            db.workday_minutes_worked_1 = 0
-            db.workday_minutes_worked_2 = 0
-            db.workday_minutes_worked_3 = 0
-        db.write_db()
-        self.send_response(302)
-        self.send_header('Location', '/')
-        self.end_headers()
+        try:
+            length = int(self.headers['content-length'])
+            postvars = parse_qs(self.rfile.read(length).decode(), keep_blank_values=1)
+            db = IncomeDB()
+            db.workday_minutes_worked_1 = int(postvars['workday_minutes_worked_1'][0])
+            db.workday_minutes_worked_2 = int(postvars['workday_minutes_worked_2'][0])
+            db.workday_minutes_worked_3 = int(postvars['workday_minutes_worked_3'][0])
+            db.workday_hourly_rate_1 = int(postvars['workday_hourly_rate_1'][0])
+            db.workday_hourly_rate_2 = int(postvars['workday_hourly_rate_2'][0])
+            db.workday_hourly_rate_3 = int(postvars['workday_hourly_rate_3'][0])
+            db.year_goal = int(postvars['year_goal'][0])
+            db.workdays_per_month = int(postvars['workdays_per_month'][0])
+            if 'finish' in postvars.keys():
+                day_income = (db.workday_minutes_worked_1 / 60.0) * db.workday_hourly_rate_1
+                day_income += (db.workday_minutes_worked_2 / 60.0) * db.workday_hourly_rate_2
+                day_income += (db.workday_minutes_worked_3 / 60.0) * db.workday_hourly_rate_3
+                db.year_income += day_income
+                db.month_income += day_income
+                db.week_income += day_income
+                db.workday_minutes_worked_1 = 0
+                db.workday_minutes_worked_2 = 0
+                db.workday_minutes_worked_3 = 0
+            db.write_db()
+            self.send_response(302)
+            self.send_header('Location', '/')
+            self.end_headers()
+        except PlomException as e:
+            self.fail_400(e) 
 
     def do_GET(self):
         import datetime
         import calendar
 
     def do_GET(self):
         import datetime
         import calendar
-        db = Database() #load_db()
-        today = datetime.datetime.now()
-        update_db = False
-        if today.year != db.timestamp_year:
-            db.timestamp_year = today.year
-            db.timestamp_month = today.month
-            db.year_income = 0
-            db.month_income = 0
-            update_db = True
-        if today.month != db.timestamp_month:
-            db.timestamp_month = today.month
-            db.month_income = 0
-            update_db = True
-        if today.isocalendar()[1] != db.timestamp_week:
-            db.timestamp_week = today.isocalendar()[1]
-            db.week_income = 0
-            update_db = True
-        if update_db:
-            print("Resetting timestamp")
-            db.write_db()
-        day_of_year = today.toordinal() - datetime.date(today.year, 1, 1).toordinal() + 1
-        year_length = 365 + calendar.isleap(today.year)
-        workday_goal = db.year_goal / 12 / db.workdays_per_month
-        workdays_per_week = (db.workdays_per_month * 12) / (year_length / 7)
-        month_goal = db.year_goal / 12
-        week_goal = db.year_goal / (year_length / 7)
-        day_income = (db.workday_minutes_worked_1 / 60.0) * db.workday_hourly_rate_1
-        day_income += (db.workday_minutes_worked_2 / 60.0) * db.workday_hourly_rate_2
-        day_income += (db.workday_minutes_worked_3 / 60.0) * db.workday_hourly_rate_3
-        year_plus = db.year_income + day_income
-        month_plus = db.month_income + day_income
-        week_plus = db.week_income + day_income
-        progress_time_year = day_of_year / year_length
-        progress_time_month = today.day / calendar.monthrange(today.year, today.month)[1]
-        progress_time_week = today.weekday() / 7
-        progress_bars = [ProgressBar("year", year_plus, db.year_goal, progress_time_year),
-                         ProgressBar("month", month_plus, month_goal, progress_time_month),
-                         ProgressBar("week", week_plus, week_goal, progress_time_week),
-                         ProgressBar("workday", day_income, workday_goal)]
-        page = tmpl.render(
-                progress_bars = progress_bars,
-                workday_hourly_rate_1 = db.workday_hourly_rate_1,
-                workday_minutes_worked_1 = db.workday_minutes_worked_1,
-                workday_hourly_rate_2 = db.workday_hourly_rate_2,
-                workday_minutes_worked_2 = db.workday_minutes_worked_2,
-                workday_hourly_rate_3 = db.workday_hourly_rate_3,
-                workday_minutes_worked_3 = db.workday_minutes_worked_3,
-                year_goal = db.year_goal,
-                month_goal = month_goal,
-                week_goal = week_goal,
-                workdays_per_month = db.workdays_per_month,
-                workday_goal = workday_goal,
-                workdays_per_week = workdays_per_week,
-                )
-        self.send_response(200)
-        self.send_header("Content-type", "text/html")
-        self.end_headers()
-        self.wfile.write(bytes(page, "utf-8"))
-
-    def fail_on_lockfile(self):
-        if os.path.exists(lock_file):
-            self.send_response(400)
-            self.end_headers()
-            self.wfile.write(bytes("Sorry, lock file!", "utf-8"))
-            return True
-        return False
+        try:
+            db = IncomeDB()
+            today = datetime.datetime.now()
+            update_db = False
+            if today.year != db.timestamp_year:
+                db.timestamp_year = today.year
+                db.timestamp_month = today.month
+                db.year_income = 0
+                db.month_income = 0
+                update_db = True
+            if today.month != db.timestamp_month:
+                db.timestamp_month = today.month
+                db.month_income = 0
+                update_db = True
+            if today.isocalendar()[1] != db.timestamp_week:
+                db.timestamp_week = today.isocalendar()[1]
+                db.week_income = 0
+                update_db = True
+            if update_db:
+                print("Resetting timestamp")
+                db.write_db()
+            day_of_year = today.toordinal() - datetime.date(today.year, 1, 1).toordinal() + 1
+            year_length = 365 + calendar.isleap(today.year)
+            workday_goal = db.year_goal / 12 / db.workdays_per_month
+            workdays_per_week = (db.workdays_per_month * 12) / (year_length / 7)
+            month_goal = db.year_goal / 12
+            week_goal = db.year_goal / (year_length / 7)
+            day_income = (db.workday_minutes_worked_1 / 60.0) * db.workday_hourly_rate_1
+            day_income += (db.workday_minutes_worked_2 / 60.0) * db.workday_hourly_rate_2
+            day_income += (db.workday_minutes_worked_3 / 60.0) * db.workday_hourly_rate_3
+            year_plus = db.year_income + day_income
+            month_plus = db.month_income + day_income
+            week_plus = db.week_income + day_income
+            progress_time_year = day_of_year / year_length
+            progress_time_month = today.day / calendar.monthrange(today.year, today.month)[1]
+            progress_time_week = today.weekday() / 7
+            progress_bars = [ProgressBar("year", year_plus, db.year_goal, progress_time_year),
+                             ProgressBar("month", month_plus, month_goal, progress_time_month),
+                             ProgressBar("week", week_plus, week_goal, progress_time_week),
+                             ProgressBar("workday", day_income, workday_goal)]
+            page = tmpl.render(
+                    progress_bars = progress_bars,
+                    workday_hourly_rate_1 = db.workday_hourly_rate_1,
+                    workday_minutes_worked_1 = db.workday_minutes_worked_1,
+                    workday_hourly_rate_2 = db.workday_hourly_rate_2,
+                    workday_minutes_worked_2 = db.workday_minutes_worked_2,
+                    workday_hourly_rate_3 = db.workday_hourly_rate_3,
+                    workday_minutes_worked_3 = db.workday_minutes_worked_3,
+                    year_goal = db.year_goal,
+                    month_goal = month_goal,
+                    week_goal = week_goal,
+                    workdays_per_month = db.workdays_per_month,
+                    workday_goal = workday_goal,
+                    workdays_per_week = workdays_per_week,
+                    )
+            self.send_HTML(page)
+        except PlomException as e:
+            self.fail_400(e) 
 
 if __name__ == "__main__":       
 
 if __name__ == "__main__":       
-    webServer = HTTPServer((hostName, serverPort), MyServer)
-    print(f"Server started http://{hostName}:{serverPort}")
-    try:
-        webServer.serve_forever()
-    except KeyboardInterrupt:
-        pass
-    webServer.server_close()
-    print("Server stopped.")
+    run_server(server_port, IncomeServer)
index c004d22126846415a916e02a6bc4aad6052df9bf..b4d9fd99191af8cdf3a45d2686654b4b371eb3fe 100755 (executable)
--- a/ledger.py
+++ b/ledger.py
@@ -5,12 +5,9 @@ import jinja2
 import decimal
 from datetime import datetime, timedelta
 from urllib.parse import parse_qs, urlparse
 import decimal
 from datetime import datetime, timedelta
 from urllib.parse import parse_qs, urlparse
-hostName = "localhost"
-serverPort = 8082
+from plomlib import PlomDB, PlomException, run_server, run_server, PlomServer
 
 
-
-class HandledException(Exception):
-    pass
+server_port = 8082
 
 
 def apply_booking_to_account_balances(account_sums, account, currency, amount):
 
 
 def apply_booking_to_account_balances(account_sums, account, currency, amount):
@@ -84,7 +81,7 @@ def parse_lines(lines, validate_bookings=True):
             if inside_booking:
                 # assume we finished a booking, finalize, and commit to DB
                 if len(booking_lines) < 2:
             if inside_booking:
                 # assume we finished a booking, finalize, and commit to DB
                 if len(booking_lines) < 2:
-                    raise HandledException(f"{prefix} booking ends to early")
+                    raise PlomException(f"{prefix} booking ends to early")
                 booking = Booking(date_string, description, booking_lines, start_line, validate_bookings)
                 bookings += [booking]
             # expect new booking to follow so re-zeroall booking data
                 booking = Booking(date_string, description, booking_lines, start_line, validate_bookings)
                 bookings += [booking]
             # expect new booking to follow so re-zeroall booking data
@@ -110,21 +107,21 @@ def parse_lines(lines, validate_bookings=True):
             try:
                 datetime.strptime(date_string, '%Y-%m-%d')
             except ValueError:
             try:
                 datetime.strptime(date_string, '%Y-%m-%d')
             except ValueError:
-                raise HandledException(f"{prefix} bad date string: {date_string}")
+                raise PlomException(f"{prefix} bad date string: {date_string}")
             if last_date > date_string:
             if last_date > date_string:
-                raise HandledException(f"{prefix} out-of-order-date")
+                raise PlomException(f"{prefix} out-of-order-date")
             last_date = date_string
             try:
                 description = toks[1]
             except IndexError:
             last_date = date_string
             try:
                 description = toks[1]
             except IndexError:
-                raise HandledException(f"{prefix} bad description: {description}")
+                raise PlomException(f"{prefix} bad description: {description}")
             inside_booking = True
             booking_lines += [non_comment]
             continue
         # otherwise, read as transfer data
         toks = non_comment.split()  # ignore specification's allowance of single spaces in names
         if len(toks) > 3:
             inside_booking = True
             booking_lines += [non_comment]
             continue
         # otherwise, read as transfer data
         toks = non_comment.split()  # ignore specification's allowance of single spaces in names
         if len(toks) > 3:
-            raise HandledException(f"{prefix} too many booking line tokens: {toks}")
+            raise PlomException(f"{prefix} too many booking line tokens: {toks}")
         amount, currency = None, None
         account_name = toks[0]
         if account_name[0] == '[' and account_name[-1] == ']':
         amount, currency = None, None
         account_name = toks[0]
         if account_name[0] == '[' and account_name[-1] == ']':
@@ -140,10 +137,10 @@ def parse_lines(lines, validate_bookings=True):
                 try:
                     amount = decimal.Decimal(toks[2])
                 except decimal.InvalidOperation:
                 try:
                     amount = decimal.Decimal(toks[2])
                 except decimal.InvalidOperation:
-                    raise HandledException(f"{prefix} no decimal number in: {toks[1:]}")
+                    raise PlomException(f"{prefix} no decimal number in: {toks[1:]}")
             currency = toks[i_currency]
             if currency[0] in decimal_chars:
             currency = toks[i_currency]
             if currency[0] in decimal_chars:
-                raise HandledException(f"{prefix} currency starts with int, dot, or minus: {currency}")
+                raise PlomException(f"{prefix} currency starts with int, dot, or minus: {currency}")
         elif len(toks) == 2:
             value = toks[1]
             inside_amount = False
         elif len(toks) == 2:
             value = toks[1]
             inside_amount = False
@@ -167,25 +164,25 @@ def parse_lines(lines, validate_bookings=True):
                 if inside_amount:
                     if c not in decimal_chars:
                         if len(currency) > 0:
                 if inside_amount:
                     if c not in decimal_chars:
                         if len(currency) > 0:
-                            raise HandledException(f"{prefix} amount has non-decimal chars: {value}")
+                            raise PlomException(f"{prefix} amount has non-decimal chars: {value}")
                         inside_currency = True
                         inside_amount = False
                         currency += c
                         continue
                     if c == '-' and len(amount_string) > 1:
                         inside_currency = True
                         inside_amount = False
                         currency += c
                         continue
                     if c == '-' and len(amount_string) > 1:
-                        raise HandledException(f"{prefix} amount has non-start '-': {value}")
+                        raise PlomException(f"{prefix} amount has non-start '-': {value}")
                     if c == '.':
                         if dots_counted > 1:
                     if c == '.':
                         if dots_counted > 1:
-                            raise HandledException(f"{prefix} amount has multiple dots: {value}")
+                            raise PlomException(f"{prefix} amount has multiple dots: {value}")
                         dots_counted += 1
                     amount_string += c
             if len(currency) == 0:
                         dots_counted += 1
                     amount_string += c
             if len(currency) == 0:
-                raise HandledException(f"{prefix} currency missing: {value}")
+                raise PlomException(f"{prefix} currency missing: {value}")
             if len(amount_string) > 0:
                 amount = decimal.Decimal(amount_string)
         booking_lines += [(account_name, amount, currency)]
     if inside_booking:
             if len(amount_string) > 0:
                 amount = decimal.Decimal(amount_string)
         booking_lines += [(account_name, amount, currency)]
     if inside_booking:
-        raise HandledException(f"{prefix} last booking unfinished")
+        raise PlomException(f"{prefix} last booking unfinished")
     return bookings, comments
 
 
     return bookings, comments
 
 
@@ -211,7 +208,7 @@ class Booking:
             _, amount, currency = line
             if amount is None:
                 if empty_values > 0:
             _, amount, currency = line
             if amount is None:
                 if empty_values > 0:
-                    raise HandledException(f"{prefix} relates more than one empty value of same currency {currency}")
+                    raise PlomException(f"{prefix} relates more than one empty value of same currency {currency}")
                 empty_values += 1
                 continue
             if currency not in sums:
                 empty_values += 1
                 continue
             if currency not in sums:
@@ -220,14 +217,14 @@ class Booking:
         if empty_values == 0:
             for k, v in sums.items():
                 if v != 0:
         if empty_values == 0:
             for k, v in sums.items():
                 if v != 0:
-                    raise HandledException(f"{prefix} does not add up to zero / {k} {v}")
+                    raise PlomException(f"{prefix} does not add up to zero / {k} {v}")
         else:
             sinkable = False
             for k, v in sums.items():
                 if v != 0:
                     sinkable = True
             if not sinkable:
         else:
             sinkable = False
             for k, v in sums.items():
                 if v != 0:
                     sinkable = True
             if not sinkable:
-                raise HandledException(f"{prefix} has empty value that cannot be filled")
+                raise PlomException(f"{prefix} has empty value that cannot be filled")
 
     def parse_booking_lines_to_account_changes(self):
         account_changes = {}
 
     def parse_booking_lines_to_account_changes(self):
         account_changes = {}
@@ -253,76 +250,25 @@ class Booking:
 
 
 
 
 
 
-class Database:
+class LedgerDB(PlomDB):
 
     def __init__(self):
 
     def __init__(self):
-        db_name = "_ledger"
-        self.db_file = db_name + ".json"
-        self.lock_file = db_name+ ".lock"
         self.bookings = []
         self.comments = []
         self.real_lines = []
         self.bookings = []
         self.comments = []
         self.real_lines = []
-        if os.path.exists(self.db_file):
-            with open(self.db_file, "r") as f:
-                self.real_lines += [l.rstrip() for l in f.readlines()]
+        super().__init__('_ledger')
         ret = parse_lines(self.real_lines)
         self.bookings += ret[0]
         self.comments += ret[1]
 
         ret = parse_lines(self.real_lines)
         self.bookings += ret[0]
         self.comments += ret[1]
 
+    def read_db_file(self, f):
+        self.real_lines += [l.rstrip() for l in f.readlines()]
+
     def get_lines(self, start, end):
         return self.real_lines[start:end]
 
     def write_db(self, text, mode='w'):
     def get_lines(self, start, end):
         return self.real_lines[start:end]
 
     def write_db(self, text, mode='w'):
-        import shutil
-        if os.path.exists(self.lock_file):
-            raise HandledException('Sorry, lock file!')
-        f = open(self.lock_file, 'w+')
-        f.close()
-
-        # collect modification times of numbered .bak files
-        bak_prefix = f'{self.db_file}.bak.'
-        backup_dates = []
-        i = 0
-        bak_as = f'{bak_prefix}{i}'
-        while os.path.exists(bak_as):
-            mod_time = os.path.getmtime(bak_as)
-            backup_dates += [str(datetime.fromtimestamp(mod_time))]
-            i += 1
-            bak_as = f'{bak_prefix}{i}'
-
-        # collect what numbered .bak files to save: the older, the fewer; for each
-        # timedelta, keep the newest file that's older
-        ages_to_keep = [timedelta(minutes=4**i) for i in range(0, 8)]
-        now = datetime.now() 
-        to_save = []
-        for age in ages_to_keep:
-            limit = now - age 
-            for i, date in enumerate(reversed(backup_dates)):
-                if datetime.strptime(date, '%Y-%m-%d %H:%M:%S.%f') < limit:
-                    unreversed_i = len(backup_dates) - i - 1
-                    if unreversed_i not in to_save:
-                        to_save += [unreversed_i]
-                    break
-
-        # remove redundant backup files 
-        j = 0
-        for i in to_save:
-            if i != j:
-                source = f'{bak_prefix}{i}'
-                target = f'{bak_prefix}{j}'
-                shutil.move(source, target)
-            j += 1
-        for i in range(j, len(backup_dates)):
-            try:
-                os.remove(f'{bak_prefix}{i}')
-            except FileNotFoundError:
-                pass
-
-        # put copy of current state at end of bak list 
-        shutil.copy(self.db_file, f'{bak_prefix}{j}')
-        with open(self.db_file, mode) as f:
-            f.write(text);
-        os.remove(self.lock_file)
+        self.write_text_to_db(text)
 
     def insert_at_date(self, lines, date):
         start_at = len(self.real_lines)
 
     def insert_at_date(self, lines, date):
         start_at = len(self.real_lines)
@@ -486,7 +432,7 @@ class Database:
         return ret
 
 
         return ret
 
 
-class MyServer(BaseHTTPRequestHandler):
+class LedgerServer(PlomServer):
     header = """<html>
 <meta charset="UTF-8">
 <style>
     header = """<html>
 <meta charset="UTF-8">
 <style>
@@ -544,7 +490,7 @@ input[type=number] { text-align: right; font-family: monospace; }
             postvars = parse_qs(self.rfile.read(length).decode(), keep_blank_values=1)
             start = int(postvars['start'][0])
             end = int(postvars['end'][0])
             postvars = parse_qs(self.rfile.read(length).decode(), keep_blank_values=1)
             start = int(postvars['start'][0])
             end = int(postvars['end'][0])
-            db = Database()
+            db = LedgerDB()
             add_empty_line = None
             lines = []
             # get inputs
             add_empty_line = None
             lines = []
             # get inputs
@@ -585,7 +531,7 @@ input[type=number] { text-align: right; font-family: monospace; }
                 else:
                     edit_content = self.add_free(db, start, end)
                 self.send_HTML(self.header + edit_content + self.footer)
                 else:
                     edit_content = self.add_free(db, start, end)
                 self.send_HTML(self.header + edit_content + self.footer)
-        except HandledException as e:
+        except PlomException as e:
             self.fail_400(e)
 
     def do_GET(self):
             self.fail_400(e)
 
     def do_GET(self):
@@ -594,7 +540,7 @@ input[type=number] { text-align: right; font-family: monospace; }
             params = parse_qs(parsed_url.query)
             start = int(params.get('start', ['0'])[0])
             end = int(params.get('end', ['0'])[0])
             params = parse_qs(parsed_url.query)
             start = int(params.get('start', ['0'])[0])
             end = int(params.get('end', ['0'])[0])
-            db = Database()
+            db = LedgerDB()
             page = self.header
             if parsed_url.path == '/balance':
                 stop = params.get('stop', [None])[0]
             page = self.header
             if parsed_url.path == '/balance':
                 stop = params.get('stop', [None])[0]
@@ -619,23 +565,9 @@ input[type=number] { text-align: right; font-family: monospace; }
                 page += self.ledger_as_html(db)
             page += self.footer
             self.send_HTML(page)
                 page += self.ledger_as_html(db)
             page += self.footer
             self.send_HTML(page)
-        except HandledException as e:
+        except PlomException as e:
             self.fail_400(e)
 
             self.fail_400(e)
 
-    def fail_400(self, e):
-        page = f'{self.header}ERROR: {e}{self.footer}'
-        self.send_HTML(page, 400)
-
-    def send_HTML(self, html, code=200):
-        self.send_code_and_headers(code, [('Content-type', 'text/html')])
-        self.wfile.write(bytes(html, "utf-8"))
-
-    def send_code_and_headers(self, code, headers=[]):
-        self.send_response(code)
-        for fieldname, content in headers:
-            self.send_header(fieldname, content)
-        self.end_headers()
-
     def booking_lines_from_postvars(self, postvars, db):
         add_empty_line = None
         date = postvars['date'][0]
     def booking_lines_from_postvars(self, postvars, db):
         add_empty_line = None
         date = postvars['date'][0]
@@ -678,7 +610,7 @@ input[type=number] { text-align: right; font-family: monospace; }
                 for currency in temp_bookings[0].sink:
                     amount = temp_bookings[0].sink[currency]
                     lines += [f'Assets  {amount:.2f} {currency}']
                 for currency in temp_bookings[0].sink:
                     amount = temp_bookings[0].sink[currency]
                     lines += [f'Assets  {amount:.2f} {currency}']
-            except HandledException:
+            except PlomException:
                 pass
         if 'add_taxes' in postvars.keys():
             lines += db.add_taxes(lines, finish=False)
                 pass
         if 'add_taxes' in postvars.keys():
             lines += db.add_taxes(lines, finish=False)
@@ -790,7 +722,7 @@ input[type=number] { text-align: right; font-family: monospace; }
         lines = temp_lines if len(''.join(temp_lines)) > 0 else db.get_lines(start, end)
         bookings, comments = parse_lines(lines, validate_bookings=False)
         if len(bookings) > 1:
         lines = temp_lines if len(''.join(temp_lines)) > 0 else db.get_lines(start, end)
         bookings, comments = parse_lines(lines, validate_bookings=False)
         if len(bookings) > 1:
-            raise HandledException('can only structurally edit single Booking')
+            raise PlomException('can only structurally edit single Booking')
         if add_empty_line is not None:
             comments = comments[:add_empty_line+1] + [''] + comments[add_empty_line+1:]
             booking = bookings[0]
         if add_empty_line is not None:
             comments = comments[:add_empty_line+1] + [''] + comments[add_empty_line+1:]
             booking = bookings[0]
@@ -870,11 +802,4 @@ input[type=number] { text-align: right; font-family: monospace; }
 
 
 if __name__ == "__main__":  
 
 
 if __name__ == "__main__":  
-    webServer = HTTPServer((hostName, serverPort), MyServer)
-    print(f"Server started http://{hostName}:{serverPort}")
-    try:
-        webServer.serve_forever()
-    except KeyboardInterrupt:
-        pass
-    webServer.server_close()
-    print("Server stopped.")
+    run_server(server_port, LedgerServer)
diff --git a/plomlib.py b/plomlib.py
new file mode 100644 (file)
index 0000000..9dac712
--- /dev/null
@@ -0,0 +1,119 @@
+import os
+from http.server import BaseHTTPRequestHandler 
+
+
+class PlomException(Exception):
+    pass
+
+
+class PlomDB:
+
+    def __init__(self, db_name):
+        self.db_file = db_name + ".json"
+        self.lock_file = db_name+ ".lock"
+        if os.path.exists(self.db_file):
+            with open(self.db_file, "r") as f:
+                self.read_db_file(f)
+
+    def lock(self):
+        if os.path.exists(self.lock_file):
+            raise PlomException('Sorry, lock file!')
+        f = open(self.lock_file, 'w+')
+        f.close()
+
+    def unlock(self):
+        os.remove(self.lock_file)
+
+    def backup(self):
+        import shutil
+        from datetime import datetime, timedelta
+        # collect modification times of numbered .bak files
+        bak_prefix = f'{self.db_file}.bak.'
+        backup_dates = []
+        i = 0
+        bak_as = f'{bak_prefix}{i}'
+        while os.path.exists(bak_as):
+            mod_time = os.path.getmtime(bak_as)
+            backup_dates += [str(datetime.fromtimestamp(mod_time))]
+            i += 1
+            bak_as = f'{bak_prefix}{i}'
+
+        # collect what numbered .bak files to save: the older, the fewer; for each
+        # timedelta, keep the newest file that's older
+        ages_to_keep = [timedelta(minutes=4**i) for i in range(0, 8)]
+        now = datetime.now() 
+        to_save = []
+        for age in ages_to_keep:
+            limit = now - age 
+            for i, date in enumerate(reversed(backup_dates)):
+                if datetime.strptime(date, '%Y-%m-%d %H:%M:%S.%f') < limit:
+                    unreversed_i = len(backup_dates) - i - 1
+                    if unreversed_i not in to_save:
+                        to_save += [unreversed_i]
+                    break
+
+        # remove redundant backup files 
+        j = 0
+        for i in to_save:
+            if i != j:
+                source = f'{bak_prefix}{i}'
+                target = f'{bak_prefix}{j}'
+                shutil.move(source, target)
+            j += 1
+        for i in range(j, len(backup_dates)):
+            try:
+                os.remove(f'{bak_prefix}{i}')
+            except FileNotFoundError:
+                pass
+
+        # put copy of current state at end of bak list 
+        shutil.copy(self.db_file, f'{bak_prefix}{j}')
+
+    def write_text_to_db(self, text, mode='w'):
+        self.lock()
+        self.backup()
+        with open(self.db_file, mode) as f:
+            f.write(text);
+        self.unlock()
+
+
+class PlomServer(BaseHTTPRequestHandler): 
+    header = ''
+    footer = ''
+
+    def run(self, port):
+        from http.server import HTTPServer
+        webServer = HTTPServer(('localhost', port), type(self))
+        print(f"Server started http://localhost:{port}")
+        try:
+            webServer.serve_forever()
+        except KeyboardInterrupt:
+            pass
+        webServer.server_close()
+        print("Server stopped.")
+
+    def fail_400(self, e):
+        page = f'{self.header}ERROR: {e}{self.footer}'
+        self.send_HTML(page, 400)
+
+    def send_HTML(self, html, code=200):
+        self.send_code_and_headers(code, [('Content-type', 'text/html')])
+        self.wfile.write(bytes(html, "utf-8"))
+
+    def send_code_and_headers(self, code, headers=[]):
+        self.send_response(code)
+        for fieldname, content in headers:
+            self.send_header(fieldname, content)
+        self.end_headers()
+
+
+def run_server(port, server_class):
+    from http.server import HTTPServer
+    webServer = HTTPServer(('localhost', port), server_class)
+    print(f"Server started http://localhost:{port}")
+    try:
+        webServer.serve_forever()
+    except KeyboardInterrupt:
+        pass
+    webServer.server_close()
+    print("Server stopped.")