Synnefo

# Copyright 2012 - 2013 GRNET S.A. All rights reserved.

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import json

import csv

import functools

import operator

from datetime import datetime

from django.utils.timesince import timesince, timeuntil

from django.db.models.query import QuerySet

from synnefo.util.text import uenc, udec

def parse_bool(value, strict=True):

    """Convert a string to boolen value.

    If strict is True, then ValueError will be raised, if the string can not be

    converted to boolean. Otherwise the string will be returned as is.

    """

    if value.lower() in ("yes", "true", "t", "1"):

        return True

    if value.lower() in ("no", "false", "f", "0"):

        return False

    if strict:

        raise ValueError("Cannot convert '%s' to boolean value" % value)

    else:

        return value

def format_bool(b):

    """Convert a boolean value to YES or NO."""

    return "YES" if b else "NO"

def format_date(d):

    if not d:

        return ""

    if d < datetime.now():

        return timesince(d) + " ago"

    else:

        return "in " + timeuntil(d)

def filter_results(results, filters):

    if isinstance(results, QuerySet):

        return filter_queryset_results(results, filters)

    elif isinstance(results, list):

        return filter_object_results(results, filters)

    else:

        raise ValueError("Invalid type for results argument: %s", results)

def parse_queryset_filters(filters):

    """Parse a string into lookup parameters for QuerySet.filter(**kwargs).

    This functions converts a string of comma-separated key 'cond' val triples

    to two dictionaries, containing lookup parameters to be used for filter

    and exclude functions of QuerySet.

    e.g. filter_by="foo>=2, baz!=4" -> ({"foo__gte": "2"}, {"baz": "4"})

    """

    OP_MAP = [

        (">=", "__gte"),

        ("=>", "__gte"),

        (">",  "__gt"),

        ("<=", "__lte"),

        ("=<", "__lte"),

        ("<", "__lt"),

        ("=", ""),

        ]

    filter_dict = {}

    exclude_dict = {}

    for filter_str in filters.split(","):

        if "!=" in filter_str:

            key, val = filter_str.split("!=")

            exclude_dict[key] = parse_bool(val, strict=False)

            continue

        for op, new_op in OP_MAP:

            if op in filter_str:

                key, val = filter_str.split(op)

                filter_dict[key + new_op] = parse_bool(val, strict=False)

                break

        else:

            raise ValueError("Unknown filter expression: %s" % filter_str)

    return (filter_dict, exclude_dict)

def filter_queryset_results(results, filters):

    filter_dict, exclude_dict = parse_queryset_filters(filters)

    return results.exclude(**exclude_dict).filter(**filter_dict)

def parse_object_filters(filters):

    OP_MAP = [

        (">=", operator.ge),

        ("=>", operator.ge),

        (">",  operator.gt),

        ("<=", operator.le),

        ("=<", operator.le),

        ("<", operator.lt),

        ("!=", operator.ne),

        ("=", operator.eq),

    ]

    filters = []

    for filter_str in filters.split(","):

        for op, op_func in OP_MAP:

            if op in filter_str:

                key, val = filter_str.split(op)

                filters.append((key.strip(), op_func, val.strip()))

                break

        else:

            raise ValueError("Unknown filter expression: %s" % filter_str)

    return filters

def filter_object_results(results, filters):

    results = list(results)

    if results is []:

        return results

    zero_result = results[0]

    for key, op_func, val in parse_object_filters(filters):

        val_type = type(getattr(zero_result, key))

        results = filter(lambda x: op_func(getattr(x, key), val_type(val)),

                         results)

    return results

def pprint_table(out, table, headers=None, output_format='pretty',

                 separator=None, vertical=False, title=None):

    """Print a pretty, aligned string representation of table.

    Works by finding out the max width of each column and padding to data

    to this value.

    """

    assert(isinstance(table, (list, tuple))), "Invalid table type"

    if headers:

        assert(isinstance(headers, (list, tuple))), "Invalid headers type"

    sep = separator if separator else "  "

    def stringnify(obj):

        if isinstance(obj, (unicode, str)):

            return udec(obj)

        else:

            return str(obj)

    if headers:

        headers = map(stringnify, headers)

    table = [map(stringnify, row) for row in table]

    if output_format == "json":

        assert(headers is not None), "json output format requires headers"

        table = [dict(zip(headers, row)) for row in table]

        out.write(json.dumps(table, indent=4))

        out.write("\n")

    elif output_format == "csv":

        cw = csv.writer(out)

        if headers:

            table.insert(0, headers)

        table = map(functools.partial(map, uenc), table)

        cw.writerows(table)

    elif output_format == "pretty":

        if vertical:

            assert(len(table) == 1)

            row = table[0]

            max_key = max(map(len, headers))

            for row in table:

                for (k, v) in zip(headers, row):

                    k = uenc(k.ljust(max_key))

                    v = uenc(v)

                    out.write("%s: %s\n" % (k, v))

        else:

            # Find out the max width of each column

            columns = [headers] + table if headers else table

            widths = [max(map(len, col)) for col in zip(*(columns))]

            t_length = sum(widths) + len(sep) * (len(widths) - 1)

            if title is not None:

                t_length = max(t_length, len(title))

                out.write("-" * t_length + "\n")

                out.write(title.center(t_length) + "\n")

                out.write("-" * t_length + "\n")

            if headers:

                # pretty print the headers

                line = sep.join(uenc(v.rjust(w))

                                for v, w in zip(headers, widths))

                out.write(line + "\n")

                out.write("-" * t_length + "\n")

            # print the rest table

            for row in table:

                line = sep.join(uenc(v.rjust(w)) for v, w in zip(row, widths))

                out.write(line + "\n")

    else:

        raise ValueError("Unknown output format '%s'" % output_format)