#!/usr/bin/env python3
import os
import re
import sys
from datetime import datetime
from pytz import timezone, AmbiguousTimeError, NonExistentTimeError

import psycopg

drive_name_re = re.compile(r'attrlog\.(.*).ata.csv')

conn = psycopg.connect("dbname=smartmontools")


def create_tables():
    with conn.cursor() as cur:
        cur.execute("START TRANSACTION")
        cur.execute("""
            CREATE TABLE device (
                id serial primary key,
                name text,
                tell bigint default 0  -- Total number of attrlog lines imported since last time
            )""")
        cur.execute("""
            CREATE TABLE attrlog (
                time timestamptz not null,
                device_id integer references device(id) not null,
                id smallint not null,
                norm smallint,
                raw bigint,
                unique (time, device_id, id)
            )
        """)
        cur.execute("COMMIT")


def create_or_find_device(name):
    with conn.cursor() as cur:
        cur.execute("SELECT id, tell FROM device WHERE name = %s", (name,))
        row = cur.fetchone()
        if row is None:
            cur.execute("INSERT INTO device (name) VALUES (%s) RETURNING id, tell", (name,))
            row = cur.fetchone()
        return row


def set_tell(device_id, tell):
    with conn.cursor() as cur:
        cur.execute("UPDATE device SET tell = %s WHERE id = %s", (tell, device_id))


def parse_attrlog_file(filename, device_id=None, start_seek=0):
    tz_dst = timezone("Europe/Tallinn")
    utc = timezone("UTC")
    # This is a date when smartmontools switched from UTC time to local time
    # That change was done in commit b75b99551368da1a8623cd76b3c67bdd3aaceddc
    smartmontools_update_date = datetime(2021, 9, 16, 18, 00, 00)
    dst = None  # Is daylight saving time in effect?
    prev_time = None

    fd = open(filename)
    file_size = fd.seek(0, os.SEEK_END)
    fd.seek(start_seek)

    while fd.tell() != file_size:
        line = fd.readline()
        line_parts = [p for p in line.strip().split(";") if p.strip()]
        plain_dt = datetime.strptime(line_parts.pop(0), "%Y-%m-%d %H:%M:%S")

        # Debian 10 to 11 upgrade added timezone and dst support to smartmontools timestamps
        if plain_dt > smartmontools_update_date:
            tz = tz_dst
        else:
            tz = utc

        try:
            dt = tz.localize(plain_dt, is_dst=None)

            # We are currently in normal time
            cur_dst = bool(dt.dst())
            if dst != cur_dst:
                dst = cur_dst
        except (AmbiguousTimeError, NonExistentTimeError):
            # We are in Ambiguous time where localtime cant be translated to UTC
            # Hack around it by tracking previous DST and time values
            dt = tz.localize(plain_dt, is_dst=dst)
            if prev_time and prev_time > dt:
                dt = tz.localize(plain_dt, is_dst=not dst)

        prev_time = dt
        cur_dst = bool(dt.dst())

        dtu = dt.astimezone(utc)
        #print(plain_dt, dt, dtu, dst, cur_dst, sep='; ')

        if dst is None:
            dst = cur_dst

        while line_parts:
            id = int(line_parts.pop(0))
            norm = int(line_parts.pop(0))
            raw = int(line_parts.pop(0))
            yield str(dtu), id, norm, raw, device_id, fd.tell()
            # Pretty progress indicator
            if fd.tell() % 100 == 0:
                print(f"{int(((fd.tell() - start_seek) / (file_size - start_seek))*100):>5}%", end='\r')
    print()


def import_attrlog_file(filename):
    drive_name = drive_name_re.search(filename).group(1)
    print(drive_name)
    device_id, tell = create_or_find_device(drive_name)
    with conn.cursor() as cur:
        cur.execute("START TRANSACTION")
        # for row in parse_attrlog_file(filename, device_id):
        #     cur.execute("""
        #     INSERT INTO attrlog (time, id, norm, raw, device_id)
        #     VALUES (%s, %s, %s, %s, %s)
        #     """, row)
        with cur.copy("copy attrlog (time, id, norm, raw, device_id) FROM STDIN") as copy:
            for row in parse_attrlog_file(filename, device_id, tell):
                tell = row[-1]
                #print(row)
                copy.write_row(row[:-1])
        set_tell(device_id, tell)
        #cur.execute("ROLLBACK")
        cur.execute("COMMIT")


if __name__ == '__main__':
    if len(sys.argv) < 2:
        create_tables()
    else:
        import_attrlog_file(sys.argv[1])