# -*- coding: utf-8 -*-
#:vim:et:ts=4:sts=4:sw=4:
import rrdtool
import os
import os.path
import sys
import glob
import hashlib
import tempfile
import time
import syslog
import sqlite3
import traceback
import datetime
import struct
import binascii
from colorsys import hls_to_rgb

import config

def sensor_rrd_path(s):
    return '%s/sensor_%s.rrd' % (config.DATA_PATH, s)

# returns (path, sensor_name) tuples
def all_sensors():
    return [(r, os.path.basename(r[:-4])) 
        for r in glob.glob('%s/*.rrd' % config.DATA_PATH)]

def create_rrd(sensor_id):
    # start date of 10 seconds into 1970 is used so that we can
    # update with prior values straight away.
    if 'voltage' in sensor_id:
        args = [ 
                '--step', '3600',
                'DS:temp:GAUGE:7200:1:10',
                'RRA:AVERAGE:0.5:1:87600']
    else:
        args = [
                '--step', '300',
                'DS:temp:GAUGE:600:-100:500',
                'RRA:AVERAGE:0.5:1:1051200']

    rrdtool.create(sensor_rrd_path(sensor_id), 
                '--start', 'now-60d',
                *args)

# stolen from viewmtn, stolen from monotone-viz
def colour_from_string(str):
    def f(off):
        return ord(hashval[off]) / 256.0
    hashval = hashlib.sha1(str).digest()
    hue = f(5)
    li = f(1) * 0.15 + 0.55
    sat = f(2) * 0.5 + .5
    return ''.join(["%.2x" % int(x * 256) for x in hls_to_rgb(hue, li, sat)])

def graph_png(start, length):
    rrds = all_sensors()

    graph_args = []
    have_volts = False
    for n, (rrdfile, sensor) in enumerate(rrds):
        if 'avrtemp' in sensor:
            continue
        if 'voltage' in sensor:
            have_volts = True
            vname = 'scalevolts'
            graph_args.append('DEF:%(vname)s=%(rrdfile)s:temp:AVERAGE:step=3600' % locals())
            unit = 'V'
        else:
            vname = 'temp%d' % n
            graph_args.append('DEF:raw%(vname)s=%(rrdfile)s:temp:AVERAGE' % locals())
            graph_args.append('CDEF:%(vname)s=raw%(vname)s,0.1,*,2,+' % locals())
            unit = '<span face="Liberation Serif">º</span>C'

        last_value = float(rrdtool.info(rrdfile)['ds[temp].last_ds'])
        width = config.LINE_WIDTH
        legend = config.SENSOR_NAMES.get(sensor, sensor)
        colour = config.SENSOR_COLOURS.get(legend, colour_from_string(sensor))
        format_last_value = ('%f' % last_value).rstrip('0') + unit
        print_legend = '%s (%s)' % (legend, format_last_value)
        graph_args.append('LINE%(width)f:%(vname)s#%(colour)s:%(print_legend)s' % locals())

    end = int(start+length)
    start = int(start)

    tempf = tempfile.NamedTemporaryFile()
    dateformat = '%H:%M:%S %Y-%m-%d'
    watermark = ("Now %s\t"
                "Start %s\t"
                "End %s" % (
                datetime.datetime.now().strftime(dateformat),
                datetime.datetime.fromtimestamp(start).strftime(dateformat),
                datetime.datetime.fromtimestamp(end).strftime(dateformat) ))

    args = [tempf.name, '-s', str(start),
        '-e', str(end),
        '-w', str(config.GRAPH_WIDTH),
        '-h', str(config.GRAPH_HEIGHT),
        '--slope-mode',
        '--border', '0',
#        '--vertical-label', 'Voltage',
        '--y-grid', '0.1:1',
        '--dynamic-labels',
        '--grid-dash', '1:0',
        '--zoom', str(config.ZOOM),
        '--color', 'GRID#00000000',
        '--color', 'MGRID#aaaaaa',
        '--color', 'BACK#ffffff',
        '--disable-rrdtool-tag',
        '--pango-markup',
        '--watermark', watermark,
        '--imgformat', 'PNG'] \
        + graph_args
    args += ['--font', 'DEFAULT:12:%s' % config.GRAPH_FONT]
    args += ['--font', 'WATERMARK:10:%s' % config.GRAPH_FONT]
    if have_volts:
        args += ['--right-axis', '10:-20', # matches the scalevolts CDEF above
            '--right-axis-format', '%.0lf',
#            '--right-axis-label', 'Temperature'
            ]

    rrdtool.graph(*args)
    return tempf.read()

def sensor_update(sensor_id, measurements, first_real_time, time_step):
    try:
        open(sensor_rrd_path(sensor_id))
    except IOError, e:
        create_rrd(sensor_id)

    if measurements:
        values = ['%d:%f' % p for p in 
            zip((first_real_time + time_step*t for t in xrange(len(measurements))),
                measurements)]

        rrdfile = sensor_rrd_path(sensor_id)
        # XXX what to do here when it fails...
        for v in values:
            try:
                rrdtool.update(rrdfile, v)
            except rrdtool.error, e:
                print>>sys.stderr, "Bad rrdtool update '%s'" % v
                traceback.print_exc(file=sys.stderr)

        # be paranoid
        f = file(rrdfile)
        os.fsync(f.fileno())

def record_debug(lines):
    f = open('%s/debug.log' % config.DATA_PATH, 'a+')
    f.write('===== %s =====\n' % time.strftime('%a, %d %b %Y %H:%M:%S'))
    f.writelines(('%s\n' % s for s in lines))
    f.flush()
    return f

def convert_ds18b20_12bit(reading):
    value = struct.unpack('>h', binascii.unhexlify(reading))[0]
    return value * 0.0625

def parse(lines):
   
    debugf = record_debug(lines)

    entries = dict(l.split('=', 1) for l in lines)
    if len(entries) != len(lines):
        raise Exception("Keys are not unique")

    num_sensors = int(entries['sensors'])
    num_measurements = int(entries['measurements'])

    sensors = [entries['sensor_id%d' % n] for n in xrange(num_sensors)]

    meas = []
    for s in sensors:
        meas.append([])

    for n in xrange(num_measurements):
        vals = [convert_ds18b20_12bit(x) for x in entries["meas%d" % n].strip().split()]
        if len(vals) != num_sensors:
            raise Exception("Wrong number of sensors for measurement %d" % n)
        # we make an array of values for each sensor
        for s in xrange(num_sensors):
            meas[s].append(vals[s])

    avr_now = float(entries['now'])
    avr_first_time = float(entries['first_time'])
    time_step = float(entries['time_step'])

    if 'avrtemp' in entries:
        avrtemp = val_scale(int(entries['avrtemp']))
        sensor_update('avrtemp', [avrtemp], time.time(), 1)

    if 'voltage' in entries:
        voltage = 0.001 * int(entries['voltage'])
        sensor_update('voltage', [voltage], time.time(), 1)

    #sqlite 
    # - time
    # - voltage
    # - boot time

    first_real_time = time.time() - (avr_now - avr_first_time)

    for sensor_id, measurements in zip(sensors, meas):
        # XXX sqlite add
        sensor_update(sensor_id, measurements, first_real_time, time_step)

    debugf.write("Updated %d sensors\n" % len(sensors))
    debugf.flush()