# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

'''
Use pywatchman to watch source directories and perform partial |mach
build faster| builds.
'''

from __future__ import absolute_import, print_function, unicode_literals

import datetime
import sys
import time

import mozbuild.util
import mozpack.path as mozpath
from mozpack.manifests import (
    InstallManifest,
)
from mozpack.copier import (
    FileCopier,
)

# Watchman integration cribbed entirely from
# https://github.com/facebook/watchman/blob/19aebfebb0b5b0b5174b3914a879370ffc5dac37/python/bin/watchman-wait
import pywatchman


def print_line(prefix, m, now=None):
    now = now or datetime.datetime.utcnow()
    print(b'[%s %sZ] %s' % (prefix, now.isoformat(), m))


def print_copy_result(elapsed, destdir, result, verbose=True):
    COMPLETE = 'Elapsed: {elapsed:.2f}s; From {dest}: Kept {existing} existing; ' \
        'Added/updated {updated}; ' \
        'Removed {rm_files} files and {rm_dirs} directories.'

    print_line('watch', COMPLETE.format(
        elapsed=elapsed,
        dest=destdir,
        existing=result.existing_files_count,
        updated=result.updated_files_count,
        rm_files=result.removed_files_count,
        rm_dirs=result.removed_directories_count))


class FasterBuildException(Exception):
    def __init__(self, message, cause):
        Exception.__init__(self, message)
        self.cause = cause


class FasterBuildChange(object):
    def __init__(self):
        self.unrecognized = set()
        self.input_to_outputs = {}
        self.output_to_inputs = {}


class Daemon(object):
    def __init__(self, config_environment):
        self.config_environment = config_environment
        self._client = None

    @property
    def defines(self):
        defines = dict(self.config_environment.acdefines)
        # These additions work around warts in the build system: see
        # http://searchfox.org/mozilla-central/rev/ad093e98f42338effe2e2513e26c3a311dd96422/config/faster/rules.mk#92-93
        # and
        # http://searchfox.org/mozilla-central/rev/ad093e98f42338effe2e2513e26c3a311dd96422/python/mozbuild/mozbuild/backend/tup.py#244-253.
        defines.update({
            'AB_CD': 'en-US',
            'BUILD_FASTER': '1',
        })
        defines.update({
            'BOOKMARKS_INCLUDE_DIR': mozpath.join(self.config_environment.topsrcdir,
                                                  'browser', 'locales', 'en-US', 'profile'),
        })
        return defines

    @mozbuild.util.memoized_property
    def file_copier(self):
        # TODO: invalidate the file copier when the build system
        # itself changes, i.e., the underlying unified manifest
        # changes.
        file_copier = FileCopier()

        unified_manifest = InstallManifest(
            mozpath.join(self.config_environment.topobjdir,
                         'faster', 'unified_install_dist_bin'))

        unified_manifest.populate_registry(file_copier, defines_override=self.defines)

        return file_copier

    def subscribe_to_topsrcdir(self):
        self.subscribe_to_dir('topsrcdir', self.config_environment.topsrcdir)

    def subscribe_to_dir(self, name, dir_to_watch):
        query = {
            'empty_on_fresh_instance': True,
            'expression': [
                'allof',
                ['type', 'f'],
                ['not',
                 ['anyof',
                  ['dirname', '.hg'],
                  ['name', '.hg', 'wholename'],
                  ['dirname', '.git'],
                  ['name', '.git', 'wholename'],
                 ],
                ],
            ],
            'fields': ['name'],
        }
        watch = self.client.query('watch-project', dir_to_watch)
        if 'warning' in watch:
            print('WARNING: ', watch['warning'], file=sys.stderr)

        root = watch['watch']
        if 'relative_path' in watch:
            query['relative_root'] = watch['relative_path']

        # Get the initial clock value so that we only get updates.
        # Wait 30s to allow for slow Windows IO.  See
        # https://facebook.github.io/watchman/docs/cmd/clock.html.
        query['since'] = self.client.query('clock', root, {'sync_timeout': 30000})['clock']

        return self.client.query('subscribe', root, name, query)

    def changed_files(self):
        # In theory we can parse just the result variable here, but
        # the client object will accumulate all subscription results
        # over time, so we ask it to remove and return those values.
        files = set()

        data = self.client.getSubscription('topsrcdir')
        if data:
            for dat in data:
                files |= set([mozpath.normpath(mozpath.join(self.config_environment.topsrcdir, f))
                              for f in dat.get('files', [])])

        return files

    def incremental_copy(self, copier, force=False, verbose=True):
        # Just like the 'repackage' target in browser/app/Makefile.in.
        if 'cocoa' == self.config_environment.substs['MOZ_WIDGET_TOOLKIT']:
            bundledir = mozpath.join(self.config_environment.topobjdir, 'dist',
                                     self.config_environment.substs['MOZ_MACBUNDLE_NAME'],
                                     'Contents', 'Resources')
            start = time.time()
            result = copier.copy(bundledir,
                                 skip_if_older=not force,
                                 remove_unaccounted=False,
                                 remove_all_directory_symlinks=False,
                                 remove_empty_directories=False)
            print_copy_result(time.time() - start, bundledir, result, verbose=verbose)

        destdir = mozpath.join(self.config_environment.topobjdir, 'dist', 'bin')
        start = time.time()
        result = copier.copy(destdir,
                             skip_if_older=not force,
                             remove_unaccounted=False,
                             remove_all_directory_symlinks=False,
                             remove_empty_directories=False)
        print_copy_result(time.time() - start, destdir, result, verbose=verbose)

    def input_changes(self, verbose=True):
        '''
        Return an iterator of `FasterBuildChange` instances as inputs
        to the faster build system change.
        '''

        # TODO: provide the debug diagnostics we want: this print is
        # not immediately before the watch.
        if verbose:
            print_line('watch', 'Connecting to watchman')
        # TODO: figure out why a large timeout is required for the
        # client, and a robust strategy for retrying timed out
        # requests.
        self.client = pywatchman.client(timeout=5.0)

        try:
            if verbose:
                print_line('watch', 'Checking watchman capabilities')
            # TODO: restrict these capabilities to the minimal set.
            self.client.capabilityCheck(required=[
                'clock-sync-timeout',
                'cmd-watch-project',
                'term-dirname',
                'wildmatch',
            ])

            if verbose:
                print_line('watch', 'Subscribing to {}'.format(self.config_environment.topsrcdir))
            self.subscribe_to_topsrcdir()
            if verbose:
                print_line('watch', 'Watching {}'.format(self.config_environment.topsrcdir))

            input_to_outputs = self.file_copier.input_to_outputs_tree()
            for input, outputs in input_to_outputs.items():
                if not outputs:
                    raise Exception("Refusing to watch input ({}) with no outputs".format(input))

            while True:
                try:
                    _watch_result = self.client.receive()

                    changed = self.changed_files()
                    if not changed:
                        continue

                    result = FasterBuildChange()

                    for change in changed:
                        if change in input_to_outputs:
                            result.input_to_outputs[change] = set(input_to_outputs[change])
                        else:
                            result.unrecognized.add(change)

                    for input, outputs in result.input_to_outputs.items():
                        for output in outputs:
                            if output not in result.output_to_inputs:
                                result.output_to_inputs[output] = set()
                            result.output_to_inputs[output].add(input)

                    yield result

                except pywatchman.SocketTimeout:
                    # Let's check to see if we're still functional.
                    _version = self.client.query('version')

        except pywatchman.CommandError as e:
            # Abstract away pywatchman errors.
            raise FasterBuildException(e, 'Command error using pywatchman to watch {}'.format(
                self.config_environment.topsrcdir))

        except pywatchman.SocketTimeout as e:
            # Abstract away pywatchman errors.
            raise FasterBuildException(e, 'Socket timeout using pywatchman to watch {}'.format(
                self.config_environment.topsrcdir))

        finally:
            self.client.close()

    def output_changes(self, verbose=True):
        '''
        Return an iterator of `FasterBuildChange` instances as outputs
        from the faster build system are updated.
        '''
        for change in self.input_changes(verbose=verbose):
            now = datetime.datetime.utcnow()

            for unrecognized in sorted(change.unrecognized):
                print_line('watch', '! {}'.format(unrecognized), now=now)

            all_outputs = set()
            for input in sorted(change.input_to_outputs):
                outputs = change.input_to_outputs[input]

                print_line('watch', '< {}'.format(input), now=now)
                for output in sorted(outputs):
                    print_line('watch', '> {}'.format(output), now=now)
                all_outputs |= outputs

            if all_outputs:
                partial_copier = FileCopier()
                for output in all_outputs:
                    partial_copier.add(output, self.file_copier[output])

                self.incremental_copy(partial_copier, force=True, verbose=verbose)
                yield change

    def watch(self, verbose=True):
        for change in self.output_changes(verbose=verbose):
            pass