#!/usr/bin/env python
# index.py for a rudimentary key/value server by David Blume
import os
import sys
import time
import datetime
import cgi, cgitb
import filelock
import tempfile
import yaml  # You may need to "pip install pyyaml"
import texttime

cgitb.enable(display=0, logdir="/tmp")
store_name = 'store.txt'


def read_file(full_pathname):
    """ The file must be a YAML file containing a dict. """
    store = dict()
    if os.path.isfile(full_pathname):
        try:
            with filelock.FileLock(full_pathname):
                with open(full_pathname, 'r') as f:
                    store = yaml.load(f)
        except filelock.FileLockException as e:
            raise
    return store


def write_file(full_pathname, data):
    """ See http://david.dlma.com/blog/dads-project-in-the-garage """
    try:
        with filelock.FileLock(full_pathname):
            with tempfile.NamedTemporaryFile(mode='w',
                    dir=os.path.dirname(full_pathname),
                    delete=False) as f:
                yaml.dump(data, f)
                # exiting this "with" flushes, but does not sync
                f.flush()
                os.fdatasync(f.fileno())  # Faster, Unix only
                tempname = f.name
            os.rename(tempname, full_pathname)  # Atomic on Unix, not Windows
    except filelock.FileLockException as e:
        raise


def map_ip_to_location(ip):
    """ Use a meaningful location instead of an IP address where possible."""
    if ip == '67.188.28.83':
        return 'home'
    elif ip in ('50.224.7.233', '50.224.7.248'):
        return 'work'
    return ip


device_prefixes = { '1G': '(Au)',
                    '5S': '(Br)',
                    'YW': '(FW)',
                    'YY': '(Da)',
                    '2N': '(Li)',
                    '1R': '(Ty)',
                    'YU': '(Lf)',
                    'YP': '(C4)',
                  }

def map_key_to_prefix(k):
    """ Return a hint about the key if we can."""
    try:
        return "%s " % device_prefixes[k[:2]]
    except KeyError:
        pass
    return ""


def print_as_table(rows, underline_header = True):
    """ Prints rows with consistent column widths. """
    cols = zip(*rows)

    # Compute column widths by taking maximum length of values per column
    col_widths = [max(len(value) for value in col) for col in cols]

    # Create a suitable format string for nice table output
    fmt = "\t".join(["{:<%d}" % i for i in col_widths])

    # Print each row using the computed format
    if underline_header:
        print fmt.format(*rows.pop(0))
        print "\t".join([('-' * i) for i in col_widths])  # column header separator
    for row in rows:
        print fmt.format(*row)


def print_footer():
    print
    print 'Tip:'
    print 'sync_ip () { export ENV_VAR=$(curl -s "%s?k=YP008G581095,2N00FG504225"); }' % os.environ['SCRIPT_URI']
    print 'curl --data "`hostname -s`=`hostname -i`&auth=$AUTH" "%s"' % os.environ['SCRIPT_URI']
    print 'Source code at http://git.dlma.com/kvs.git/'


if __name__ == '__main__':
    localdir = os.path.abspath(os.path.dirname(sys.argv[0]))
    args = cgi.FieldStorage()
    key = None
    auth = None
    get_key = False
    auth_in_get = False
    doing_post = False

    # Find the parameters that are GET parameters
    # Could also check os.environ['REQUEST_METHOD'] == 'POST',
    # but that doesn't say which way individual params were sent.
    if os.environ['QUERY_STRING']:
        qs = os.environ['QUERY_STRING'].split('&')
        for pair in qs:
            k, v = pair.split('=')
            if k == 'k':
                get_key = True
            if k == 'auth':
                auth_in_get = True

    # Could be either GET or POST. Need to check QUERY_STRING above.
    if "k" in args:
        key = args["k"].value

    if os.environ['REQUEST_METHOD'] == 'POST':
        doing_post = True
        if not auth_in_get and "auth" in args:
            auth = args["auth"].value

    store = read_file(os.path.join(localdir, store_name))
    if get_key:
        keys = key.split(',')
        matches = sorted([(store[x]['time'], store[x]['value']) for x in keys if x in store], reverse=True)
        if matches:
            print "Content-type: text/plain; charset=utf-8\n"
            sys.stdout.write(matches[0][1])
        else:
            print 'Status: 404 Not Found\n'
    else:
        wrote_response = False
        with open('auth.txt', 'r') as f:
            authorization = f.read().strip()
        if doing_post and auth == authorization:
            print "Content-type: text/plain; charset=utf-8\n"
            for new_key in args:
                if new_key  =='auth':
                    continue
                if  len(new_key) > 80 or len(args[new_key].value) > 140:
                    print "Error: A key or value was too long."
                    sys.exit(0)
                if new_key in store and 'created' in store[new_key]:
                    created_time = store[new_key]['created']
                else:
                    created_time = int(time.time())
                store[new_key] = {'value': args[new_key].value,
                                  'time': int(time.time()),
                                  'created': created_time,
                                  'origin': os.environ['REMOTE_ADDR']}
            write_file(os.path.join(localdir, store_name), store)
            wrote_response = True
            print "OK"
        elif not os.environ['QUERY_STRING'] and not doing_post:
            # just the home page, then
            print "Content-type: text/plain; charset=UTF-8\n"
            wrote_response = True

            rows = [('key', 'value', 'created', 'updated', 'origin', 'notes'),]
            for key in sorted(store, key=lambda k: store[k]['time'], reverse=True):
                d = store[key]
                td = texttime.stringify(datetime.timedelta(seconds=time.time()-d['time']))
                created = time.strftime('%Y-%m-%d', time.localtime(d['created']))
                origin = map_ip_to_location(d['origin'])
                rows.append((key, d['value'], created, str(d['time']), origin,
                            "%supdated %s ago" % (map_key_to_prefix(key), td)))

            print_as_table(rows)
            print_footer()

        if not wrote_response:
            print 'Status: 400 Bad Request\n'