from __future__ import absolute_import
import json
import time

from mercurial import progress

"""allows users to have JSON progress bar information written to a path

Controlled by the `ui.progressfile` config. Mercurial will overwrite this file
each time the progress bar is updated.

The schema of this file is (JSON):

- topics: array of topics from oldest to newest. (last is always the active one)
- state: map of topic names to objects with keys:
    - topic (e.g. "changesets", "manifests")
    - pos: which item number out of <total> we're processing
    - total: total number of items (can change!)
    - unit: name of the type of unit being processed (e.g., "changeset")
    - item: the active item being processed (e.g., "changeset #5")
    - active: whether this is the currently active progress bar
    - units_per_sec: if active, how many <unit>s per sec we're processing
    - speed_str: if active, a human-readable string of how many <unit>s per sec
        we're processing
    - estimate_sec: an estimate of how much time is left, in seconds
    - estimate_str: if active, a human-readable string estimate of how much time
        is left (e.g. "2m30s")

config example::

    [progress]
    # Where to write progress information
    statefile = /some/path/to/file
"""
testedwith = 'ships-with-fb-hgext'

class progbarwithfile(progress.progbar):
    def progress(self, topic, pos, item='', unit='', total=None):
        super(progbarwithfile, self).progress(topic, pos, item, unit, total)
        self.writeprogress(time.time())

    def writeprogress(self, now):
        progressfile = self.ui.config('progress', 'statefile')
        if not progressfile:
            return

        topics = {}
        for topic in self.topicstates.keys():
            pos, item, unit, total = self.topicstates[topic]
            isactive = topic == self.curtopic
            cullempty = lambda str: str if str else None
            info = {
                'topic': topic,
                'pos': pos,
                'total': total,
                'unit': cullempty(unit),
                'item': cullempty(item),

                'active': isactive,
                'units_per_sec': None,
                'speed_str': None,
                'estimate_sec': None,
                'estimate_str': None,
            }
            if isactive:
                info['units_per_sec'] = cullempty(self._speed(topic, pos, now))
                info['estimate_sec'] = cullempty(self._estimate(
                    topic, pos, total, now))
                info['speed_str'] = cullempty(self.speed(topic, pos, unit, now))
                info['estimate_str'] = cullempty(self.estimate(
                    topic, pos, total, now))
            topics[topic] = info

        text = json.dumps({
            'state': topics,
            'topics': self.topics,
        }, sort_keys=True)
        try:
            with open(progressfile, 'w+') as f:
                f.write(text)
        except (IOError, OSError):
            pass

    # These duplicate some logic in progress.py.
    def _estimate(self, topic, pos, total, now):
        if total is None:
            return None
        initialpos = self.startvals[topic]
        target = total - initialpos
        delta = pos - initialpos
        if delta > 0:
            elapsed = now - self.starttimes[topic]
            return int((elapsed * (target - delta)) // delta + 1)
        return None

    def _speed(self, topic, pos, now):
        initialpos = self.startvals[topic]
        delta = pos - initialpos
        elapsed = now - self.starttimes[topic]
        return int(delta / elapsed)

def uisetup(ui):
    progress.progbar = progbarwithfile