from __future__ import unicode_literals

import contextlib
import io
import logging
import os.path
import sqlite3
import tempfile

import pre_commit.constants as C
from pre_commit import file_lock
from pre_commit import git
from pre_commit.util import CalledProcessError
from pre_commit.util import clean_path_on_failure
from pre_commit.util import cmd_output
from pre_commit.util import resource_text
from pre_commit.util import rmtree


logger = logging.getLogger('pre_commit')


def _get_default_directory():
    """Returns the default directory for the Store.  This is intentionally
    underscored to indicate that `Store.get_default_directory` is the intended
    way to get this information.  This is also done so
    `Store.get_default_directory` can be mocked in tests and
    `_get_default_directory` can be tested.
    """
    return os.environ.get('PRE_COMMIT_HOME') or os.path.join(
        os.environ.get('XDG_CACHE_HOME') or os.path.expanduser('~/.cache'),
        'pre-commit',
    )


class Store(object):
    get_default_directory = staticmethod(_get_default_directory)

    def __init__(self, directory=None):
        self.directory = directory or Store.get_default_directory()
        self.db_path = os.path.join(self.directory, 'db.db')

        if not os.path.exists(self.directory):
            os.makedirs(self.directory)
            with io.open(os.path.join(self.directory, 'README'), 'w') as f:
                f.write(
                    'This directory is maintained by the pre-commit project.\n'
                    'Learn more: https://github.com/pre-commit/pre-commit\n',
                )

        if os.path.exists(self.db_path):
            return
        with self.exclusive_lock():
            # Another process may have already completed this work
            if os.path.exists(self.db_path):  # pragma: no cover (race)
                return
            # To avoid a race where someone ^Cs between db creation and
            # execution of the CREATE TABLE statement
            fd, tmpfile = tempfile.mkstemp(dir=self.directory)
            # We'll be managing this file ourselves
            os.close(fd)
            with self.connect(db_path=tmpfile) as db:
                db.executescript(
                    'CREATE TABLE repos ('
                    '    repo TEXT NOT NULL,'
                    '    ref TEXT NOT NULL,'
                    '    path TEXT NOT NULL,'
                    '    PRIMARY KEY (repo, ref)'
                    ');',
                )
                self._create_config_table_if_not_exists(db)

            # Atomic file move
            os.rename(tmpfile, self.db_path)

    @contextlib.contextmanager
    def exclusive_lock(self):
        def blocked_cb():  # pragma: no cover (tests are single-process)
            logger.info('Locking pre-commit directory')

        with file_lock.lock(os.path.join(self.directory, '.lock'), blocked_cb):
            yield

    @contextlib.contextmanager
    def connect(self, db_path=None):
        db_path = db_path or self.db_path
        # sqlite doesn't close its fd with its contextmanager >.<
        # contextlib.closing fixes this.
        # See: https://stackoverflow.com/a/28032829/812183
        with contextlib.closing(sqlite3.connect(db_path)) as db:
            # this creates a transaction
            with db:
                yield db

    @classmethod
    def db_repo_name(cls, repo, deps):
        if deps:
            return '{}:{}'.format(repo, ','.join(sorted(deps)))
        else:
            return repo

    def _new_repo(self, repo, ref, deps, make_strategy):
        repo = self.db_repo_name(repo, deps)

        def _get_result():
            # Check if we already exist
            with self.connect() as db:
                result = db.execute(
                    'SELECT path FROM repos WHERE repo = ? AND ref = ?',
                    (repo, ref),
                ).fetchone()
                if result:
                    return result[0]

        result = _get_result()
        if result:
            return result
        with self.exclusive_lock():
            # Another process may have already completed this work
            result = _get_result()
            if result:  # pragma: no cover (race)
                return result

            logger.info('Initializing environment for {}.'.format(repo))

            directory = tempfile.mkdtemp(prefix='repo', dir=self.directory)
            with clean_path_on_failure(directory):
                make_strategy(directory)

            # Update our db with the created repo
            with self.connect() as db:
                db.execute(
                    'INSERT INTO repos (repo, ref, path) VALUES (?, ?, ?)',
                    [repo, ref, directory],
                )
        return directory

    def _complete_clone(self, ref, git_cmd):
        """Perform a complete clone of a repository and its submodules """

        git_cmd('fetch', 'origin', '--tags')
        git_cmd('checkout', ref)
        git_cmd('submodule', 'update', '--init', '--recursive')

    def _shallow_clone(self, ref, git_cmd):  # pragma: windows no cover
        """Perform a shallow clone of a repository and its submodules """

        git_config = 'protocol.version=2'
        git_cmd('-c', git_config, 'fetch', 'origin', ref, '--depth=1')
        git_cmd('checkout', ref)
        git_cmd(
            '-c', git_config, 'submodule', 'update', '--init',
            '--recursive', '--depth=1',
        )

    def clone(self, repo, ref, deps=()):
        """Clone the given url and checkout the specific ref."""

        if os.path.isdir(repo):
            repo = os.path.abspath(repo)

        def clone_strategy(directory):
            env = git.no_git_env()

            def _git_cmd(*args):
                cmd_output('git', *args, cwd=directory, env=env)

            _git_cmd('init', '.')
            _git_cmd('remote', 'add', 'origin', repo)

            try:
                self._shallow_clone(ref, _git_cmd)
            except CalledProcessError:
                self._complete_clone(ref, _git_cmd)

        return self._new_repo(repo, ref, deps, clone_strategy)

    LOCAL_RESOURCES = (
        'Cargo.toml', 'main.go', 'main.rs', '.npmignore', 'package.json',
        'pre_commit_dummy_package.gemspec', 'setup.py',
    )

    def make_local(self, deps):
        def make_local_strategy(directory):
            for resource in self.LOCAL_RESOURCES:
                contents = resource_text('empty_template_{}'.format(resource))
                with io.open(os.path.join(directory, resource), 'w') as f:
                    f.write(contents)

            env = git.no_git_env()

            # initialize the git repository so it looks more like cloned repos
            def _git_cmd(*args):
                cmd_output('git', *args, cwd=directory, env=env)

            _git_cmd('init', '.')
            _git_cmd('config', 'remote.origin.url', '<<unknown>>')
            _git_cmd('add', '.')
            git.commit(repo=directory)

        return self._new_repo(
            'local', C.LOCAL_REPO_VERSION, deps, make_local_strategy,
        )

    def _create_config_table_if_not_exists(self, db):
        db.executescript(
            'CREATE TABLE IF NOT EXISTS configs ('
            '   path TEXT NOT NULL,'
            '   PRIMARY KEY (path)'
            ');',
        )

    def mark_config_used(self, path):
        path = os.path.realpath(path)
        # don't insert config files that do not exist
        if not os.path.exists(path):
            return
        with self.connect() as db:
            # TODO: eventually remove this and only create in _create
            self._create_config_table_if_not_exists(db)
            db.execute('INSERT OR IGNORE INTO configs VALUES (?)', (path,))

    def select_all_configs(self):
        with self.connect() as db:
            self._create_config_table_if_not_exists(db)
            rows = db.execute('SELECT path FROM configs').fetchall()
            return [path for path, in rows]

    def delete_configs(self, configs):
        with self.connect() as db:
            rows = [(path,) for path in configs]
            db.executemany('DELETE FROM configs WHERE path = ?', rows)

    def select_all_repos(self):
        with self.connect() as db:
            return db.execute('SELECT repo, ref, path from repos').fetchall()

    def delete_repo(self, db_repo_name, ref, path):
        with self.connect() as db:
            db.execute(
                'DELETE FROM repos WHERE repo = ? and ref = ?',
                (db_repo_name, ref),
            )
        rmtree(path)