"""Implementation of the deep stats class.

Ported to Python 3.
"""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

from future.utils import PY2
if PY2:
    from future.builtins import filter, map, zip, ascii, chr, hex, input, next, oct, open, pow, round, super, bytes, dict, list, object, range, str, max, min  # noqa: F401

import math

from allmydata.interfaces import IImmutableFileNode
from allmydata.interfaces import IMutableFileNode
from allmydata.interfaces import IDirectoryNode
from allmydata.unknown import UnknownNode
from allmydata.uri import LiteralFileURI
from allmydata.uri import from_string
from allmydata.util import mathutil

class DeepStats(object):
    """Deep stats object.

    Holds results of the deep-stats operation.
    Used for json generation in the API."""

    # Json API version.
    # Rules:
    # - increment each time a field is removed or changes meaning.
    # - it's ok to add a new field without incrementing the version.
    API_VERSION = 1

    def __init__(self, origin):
        """Initializes DeepStats object. Sets most of the fields to 0."""
        self.monitor = None
        self.origin = origin
        self.stats = {
            'api-version': self.API_VERSION
        }
        for k in ["count-immutable-files",
                  "count-mutable-files",
                  "count-literal-files",
                  "count-files",
                  "count-directories",
                  "count-unknown",
                  "size-immutable-files",
                  #"size-mutable-files",
                  "size-literal-files",
                  "size-directories",
                  "largest-directory",
                  "largest-directory-children",
                  "largest-immutable-file",
                  #"largest-mutable-file",
                 ]:
            self.stats[k] = 0
        self.histograms = {}
        for k in ["size-files-histogram"]:
            self.histograms[k] = {} # maps (min,max) to count
        self.buckets = [(0, 0), (1, 3)]
        self.root = math.sqrt(10)

    def set_monitor(self, monitor):
        """Sets a new monitor."""
        self.monitor = monitor
        monitor.origin_si = self.origin.get_storage_index()
        monitor.set_status(self.get_results())

    def add_node(self, node, childpath):
        """Adds a node's stats to calculation."""
        if isinstance(node, UnknownNode):
            self.add("count-unknown")
        elif IDirectoryNode.providedBy(node):
            self.add("count-directories")
        elif IMutableFileNode.providedBy(node):
            self.add("count-files")
            self.add("count-mutable-files")
            # TODO: update the servermap, compute a size, add it to
            # size-mutable-files, max it into "largest-mutable-file"
        elif IImmutableFileNode.providedBy(node): # CHK and LIT
            self.add("count-files")
            size = node.get_size()
            self.histogram("size-files-histogram", size)
            theuri = from_string(node.get_uri())
            if isinstance(theuri, LiteralFileURI):
                self.add("count-literal-files")
                self.add("size-literal-files", size)
            else:
                self.add("count-immutable-files")
                self.add("size-immutable-files", size)
                self.max("largest-immutable-file", size)

    def enter_directory(self, parent, children):
        """Adds directory stats."""
        dirsize_bytes = parent.get_size()
        if dirsize_bytes is not None:
            self.add("size-directories", dirsize_bytes)
            self.max("largest-directory", dirsize_bytes)
        dirsize_children = len(children)
        self.max("largest-directory-children", dirsize_children)

    def add(self, key, value=1):
        self.stats[key] += value

    def max(self, key, value):
        self.stats[key] = max(self.stats[key], value)

    def which_bucket(self, size):
        # return (min,max) such that min <= size <= max
        # values are from the set (0,0), (1,3), (4,10), (11,31), (32,100),
        # (101,316), (317, 1000), etc: two per decade
        assert size >= 0
        i = 0
        while True:
            if i >= len(self.buckets):
                # extend the list
                new_lower = self.buckets[i-1][1]+1
                new_upper = int(mathutil.next_power_of_k(new_lower, self.root))
                self.buckets.append((new_lower, new_upper))
            maybe = self.buckets[i]
            if maybe[0] <= size <= maybe[1]:
                return maybe
            i += 1

    def histogram(self, key, size):
        bucket = self.which_bucket(size)
        h = self.histograms[key]
        if bucket not in h:
            h[bucket] = 0
        h[bucket] += 1

    def get_results(self):
        """Returns deep-stats results."""
        stats = self.stats.copy()
        for key in self.histograms:
            h = self.histograms[key]
            out = [ (bucket[0], bucket[1], h[bucket]) for bucket in h ]
            out.sort()
            stats[key] = out
        return stats

    def finish(self):
        """Finishes gathering stats."""
        return self.get_results()