#!/usr/bin/env python

import gevent.monkey
gevent.monkey.patch_all(thread=False)

from collections import defaultdict
import copy
import datetime
import errno
import httplib
import json
import os
from os import path
import traceback
import urlparse

import gevent.pywsgi

import config
import db
import fileio
import reloader

DATA_DIR = path.expanduser('~/sysvitals_data')
handlers = None

def main():
	global handlers
	handlers = {
		'datum': post_datum,
		'raw': get_raw,
		'stats': get_stats,
		'servers': get_servers,
		'register_server': register_server,
	}
	server = gevent.pywsgi.WSGIServer(('0.0.0.0', config.api_port), application)
	if config.debug:
		reloader.init(server)
	print 'listening on', config.api_port
	server.serve_forever()

class HTTPException(Exception):
	def __init__(self, code, body):
		self.code = code
		self.body = body

BASE_HEADERS = [
	('Access-Control-Allow-Origin', '*'),
	('Access-Control-Allow-Headers', 'X-Requested-With, X-Request'),
]
DEFAULT_HEADERS = BASE_HEADERS + [('Content-type', 'application/json')]
ERROR_HEADERS = BASE_HEADERS + [('Content-type', 'text/plain')]

def application(environ, start_response):
	try:
		if environ['REQUEST_METHOD'] == 'OPTIONS':
			start_response('200 OK', copy.copy(DEFAULT_HEADERS))
			return []
		split = environ['PATH_INFO'][1:].split('/')
		qs = environ['QUERY_STRING']
		if qs:
			query = urlparse.parse_qs(qs, True, True)
			for k, v in query.iteritems():
				if len(v) > 1:
					raise HTTPException(400, 'duplicate query parameter: ' + k)
				query[k] = v[0]
		else:
			query = {}
		if split[0] == 'v1':
			handler = handlers.get(split[2])
			if handler:
				body = json.dumps(handler(split, query, environ))
				start_response('200 OK', copy.copy(DEFAULT_HEADERS))
				return [body]
			else:
				print 'no handler for', split
		else:
			print 'split was', split
		raise HTTPException(404, 'unhandled path: ' + environ['PATH_INFO'])
	except HTTPException as e:
		response = '%d %s' % (e.code, httplib.responses[e.code])
		start_response(response, copy.copy(ERROR_HEADERS))
		return [e.body]
	except:
		traceback.print_exc()
		start_response('500 Internal Server Error', copy.copy(ERROR_HEADERS))
		return ['ruh roh']

def get_raw(split, query, environ):
	try:
		group_id = get_group(split, environ)
		server_id = int(split[3])
		start = datetime.datetime.strptime(query['start'], '%Y-%m-%d').date()
		end = datetime.datetime.strptime(query['end'], '%Y-%m-%d').date()
	except (IndexError, KeyError, ValueError):
		raise HTTPException(400, '')

	server_dir = path.join(DATA_DIR, str(group_id), str(server_id))
	rval = {}
	c = start
	while c <= end:
		date_str = c.isoformat()
		try:
			with open(path.join(server_dir, date_str), 'r') as f:
				data = fileio.read_stats(f)
		except IOError as e:
			if e.errno == errno.ENOENT:
				data = None
			else:
				raise
		rval[date_str] = data
		c += datetime.timedelta(days=1)
	return rval

fields = {
	'cpu': ['user', 'iowait', 'system', 'nice', 'guest', 'guest_nice', 'irq', 'softirq', 'steal', 'idle'],
	'mem': ['used', 'buffers', 'cached', 'free'],
	'net': ['bit/s_in', 'bit/s_out', 'err_in', 'err_out', 'drop_in', 'drop_out'],
}
def get_stats(split, query, environ):
	try:
		interval = int(query.get('interval', 1))
	except ValueError:
		raise HTTPException(400, 'interval must be integer')
	raw = get_raw(split, query, environ)
	dates = raw.keys()
	dates.sort()
	last_val = fileio.gen_template(-1)
	stats = defaultdict(dict)
	for date in dates:
		data = raw[date]
		if data is None:
			for field, subfields in fields.iteritems():
				for subfield in subfields:
					stats[field].setdefault(subfield, {})
					stats[field][subfield][date] = [None] * (1440 / interval)
			continue
		for field, subfields in data.items():
			if field == 'cpu':
				field_data = {}
				# subtract times from last minute, calculate total time spent each minute
				sums = [0] * 1440
				for subfield, raw_array in subfields.iteritems():
					if subfield != 'num_cpus':
						array = [None] * 1440
						for i, d in enumerate(raw_array):
							lv = last_val[field][subfield]
							if d > 0 and lv > 0:
								array[i] = d - lv
								sums[i] += array[i]
							last_val[field][subfield] = d
					field_data[subfield] = array
				# divide differences by total times
				for subfield, array in field_data.items():
					if subfield != 'num_cpus':
						for i, d in enumerate(array):
							if d > 0:
								array[i] = array[i] * subfields['num_cpus'][i] * 100 / sums[i]
					stats[field].setdefault(subfield, {})
					stats[field][subfield][date] = average(array, interval)
			elif field == 'mem':
				# translate total to free, subtract buffers and cached from used
				field_data = {}
				new_fields = ['used', 'buffers', 'cached', 'free']
				for subfield in new_fields:
					field_data[subfield] = [None] * 1440
				for i in xrange(1440):
					if subfields['total'][i] == -1:
						for nf in new_fields:
							field_data[nf][i] = None
						continue
					field_data['free'][i] = subfields['total'][i] - subfields['used'][i]
					field_data['used'][i] = subfields['used'][i] - subfields['buffers'][i] - subfields['cached'][i]
					field_data['buffers'][i] = subfields['buffers'][i]
					field_data['cached'][i] = subfields['cached'][i]
				for subfield, array in field_data.iteritems():
					stats[field].setdefault(subfield, {})
					stats[field][subfield][date] = average(array, interval)
			elif field == 'net':
				field_data = {}
				for subfield in ['bit/s_in', 'bit/s_out', 'err_in', 'err_out', 'drop_in', 'drop_out']:
					field_data[subfield] = [None] * 1440
				for i in xrange(1440):
					lv_recv = last_val['net']['bytes_recv']
					lv_sent = last_val['net']['bytes_sent']
					if lv_recv > 0:
						field_data['bit/s_in'][i] = (subfields['bytes_recv'][i] - lv_recv) * 8.0 / 60
					if lv_sent > 0:
						field_data['bit/s_out'][i] = (subfields['bytes_sent'][i] - lv_sent) * 8.0 / 60
					last_val['net']['bytes_recv'] = subfields['bytes_recv'][i]
					last_val['net']['bytes_sent'] = subfields['bytes_sent'][i]
					for subfield in ['err_in', 'err_out', 'drop_in', 'drop_out']:
						field_data[subfield][i] = subfields[subfield.replace('_', '')][i]
				for subfield, array in field_data.iteritems():
					stats[field].setdefault(subfield, {})
					stats[field][subfield][date] = average(array, interval)
			elif field == 'disk':
				field_data = {}
				for mountpoint, disk_sfs in subfields.items():
					used_key = mountpoint + '_used'
					free_key = mountpoint + '_free'
					field_data[used_key] = [None] * 1440
					field_data[free_key] = [None] * 1440
					for i in xrange(1440):
						if disk_sfs['total'][i] == -1:
							continue
						used = disk_sfs['used'][i]
						field_data[used_key][i] = used
						field_data[free_key][i] = disk_sfs['total'][i] - used
				for subfield, array in field_data.iteritems():
					stats[field].setdefault(subfield, {})
					stats[field][subfield][date] = average(array, interval)
	return stats

def post_datum(split, query, environ):
	group_id = get_group(split, environ)
	try:
		server_id = int(split[3])
	except (IndexError, ValueError):
		raise HTTPException(400, '')
	body = load_json_body(environ)
	if body.keys() != fileio.TEMPLATE.keys():
		diff = set(body.keys()).symmetric_difference(set(fileio.TEMPLATE.keys()))
		raise HTTPException(400, 'post body had missing or extra keys: ' + ','.join(diff))

	server_dir = path.join(DATA_DIR, str(group_id), str(server_id))
	try:
		os.makedirs(server_dir)
	except OSError as e:
		if e.errno != errno.EEXIST:
			raise

	# we floor to the minute, so this rounds to the nearest minute
	now = datetime.datetime.utcnow() + datetime.timedelta(seconds=29)
	data_path = path.join(server_dir, now.date().isoformat())
	try:
		with open(data_path, 'r') as f:
			stats = fileio.read_stats(f)
	except IOError as e:
		if e.errno != errno.ENOENT:
			raise
		stats = copy.deepcopy(fileio.TEMPLATE)

	index = now.hour * 60 + now.minute
	data = {}
	for field, subfields in stats.iteritems():
		field_data = {}
		if field == 'disk':
			disk = stats['disk']
			for mountpoint, datum in body['disk'].iteritems(): # iterate through body to get new mountpoints
				if mountpoint not in disk:
					disk[mountpoint] = {'total': [-1] * 1440, 'used': [-1] * 1440}
				field_data[mountpoint] = {}
				for subfield, array in disk[mountpoint].iteritems():
					array = list(array)
					array[index] = datum[subfield]
					field_data[mountpoint][subfield] = array
		else:
			for subfield, array in subfields.iteritems():
				array = list(array)
				array[index] = body[field][subfield]
				field_data[subfield] = array
		data[field] = field_data

	with open(data_path, 'w') as f:
		fileio.write_datum(f, data)
	return {'status': 'ok'}

def get_servers(split, query, environ):
	group_id = get_group(split, environ)
	return db.get_servers(group_id)

def register_server(split, query, environ):
	group_id = get_group(split, environ)
	body = load_json_body(environ)
	try:
		hostname = body['hostname']
	except KeyError:
		raise HTTPException(400, 'post body didn\'t contain "hostname" key')

	server_id = db.create_server(group_id, hostname)
	return {'server_id': server_id}

def get_group(split, environ):
	try:
		group_id = int(split[1])
	except (IndexError, ValueError):
		raise HTTPException(400, '/v1/[group_id] - group_id was not valid int')
	if 'HTTP_AUTHORIZATION' not in environ:
		raise HTTPException(401, 'no api key passed in Authorization header')
	if db.get_api_key(group_id) != environ['HTTP_AUTHORIZATION']:
		raise HTTPException(403, 'api key did not match')
	return group_id

def load_json_body(environ):
	try:
		body = json.load(environ['wsgi.input'])
	except ValueError:
		raise HTTPException(400, 'post body was not valid JSON')
	if not isinstance(body, dict):
		raise HTTPException(400, 'post body was not a JSON dictionary')
	return body

def average(array, interval):
	if interval == 1:
		return array
	averaged = []
	accum = num_values = 0
	for i, v in enumerate(array):
		if v is not None:
			accum += v
			num_values += 1
		if (i + 1) % interval == 0:
			if num_values > 0:
				averaged.append(accum / num_values)
			else:
				averaged.append(None)
			accum = num_values = 0
	return averaged

main()