# -*- coding: utf-8 -*-

# Copyright © 2012-2017 Roberto Alsina and others.

# Permission is hereby granted, free of charge, to any
# person obtaining a copy of this software and associated
# documentation files (the "Software"), to deal in the
# Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the
# Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice
# shall be included in all copies or substantial portions of
# the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
# PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
# OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

"""The main function of Nikola."""

import os
import shutil
import sys
import traceback
from collections import defaultdict

from blinker import signal
from doit.cmd_auto import Auto as DoitAuto
from doit.cmd_base import TaskLoader
from doit.cmd_clean import Clean as DoitClean
from doit.cmd_completion import TabCompletion
from doit.cmd_help import Help as DoitHelp
from doit.cmd_run import Run as DoitRun
from doit.doit_cmd import DoitMain
from doit.loader import generate_tasks
from doit.reporter import ExecutedOnlyReporter
from logbook import NullHandler

from . import __version__
from .nikola import Nikola
from .plugin_categories import Command
from .utils import (LOGGER, STDERR_HANDLER, STRICT_HANDLER,
                    ColorfulStderrHandler, get_root_dir, req_missing,
                    sys_decode)

try:
    import readline  # NOQA
except ImportError:
    pass  # This is only so raw_input/input does nicer things if it's available


import importlib.machinery

config = {}

# DO NOT USE unless you know what you are doing!
_RETURN_DOITNIKOLA = False


def main(args=None):
    """Run Nikola."""
    colorful = False
    if sys.stderr.isatty() and os.name != 'nt' and os.getenv('NIKOLA_MONO') is None and os.getenv('TERM') != 'dumb':
        colorful = True

    ColorfulStderrHandler._colorful = colorful

    if args is None:
        args = sys.argv[1:]

    oargs = args
    args = [sys_decode(arg) for arg in args]

    conf_filename = 'conf.py'
    conf_filename_changed = False
    for index, arg in enumerate(args):
        if arg[:7] == '--conf=':
            del args[index]
            del oargs[index]
            conf_filename = arg[7:]
            conf_filename_changed = True
            break

    quiet = False
    strict = False
    if len(args) > 0 and args[0] == 'build' and '--strict' in args:
        LOGGER.notice('Running in strict mode')
        STRICT_HANDLER.push_application()
        strict = True
    if len(args) > 0 and args[0] == 'build' and '-q' in args or '--quiet' in args:
        NullHandler().push_application()
        quiet = True
    if not quiet and not strict:
        NullHandler().push_application()
        STDERR_HANDLER[0].push_application()

    global config

    original_cwd = os.getcwd()

    # Those commands do not require a `conf.py`.  (Issue #1132)
    # Moreover, actually having one somewhere in the tree can be bad, putting
    # the output of that command (the new site) in an unknown directory that is
    # not the current working directory.  (does not apply to `version`)
    argname = args[0] if len(args) > 0 else None
    if argname and argname not in ['init', 'version'] and not argname.startswith('import_'):
        root = get_root_dir()
        if root:
            os.chdir(root)
        # Help and imports don't require config, but can use one if it exists
        needs_config_file = (argname != 'help') and not argname.startswith('import_')
    else:
        needs_config_file = False

    sys.path.append('')
    try:
        loader = importlib.machinery.SourceFileLoader("conf", conf_filename)
        conf = loader.load_module()
        config = conf.__dict__
    except Exception:
        if os.path.exists(conf_filename):
            msg = traceback.format_exc(0)
            LOGGER.error('"{0}" cannot be parsed.\n{1}'.format(conf_filename, msg))
            return 1
        elif needs_config_file and conf_filename_changed:
            LOGGER.error('Cannot find configuration file "{0}".'.format(conf_filename))
            return 1
        config = {}

    if conf_filename_changed:
        LOGGER.info("Using config file '{0}'".format(conf_filename))

    invariant = False

    if len(args) > 0 and args[0] == 'build' and '--invariant' in args:
        try:
            import freezegun
            freeze = freezegun.freeze_time("2038-01-01")
            freeze.start()
            invariant = True
        except ImportError:
            req_missing(['freezegun'], 'perform invariant builds')

    if config:
        if os.path.isdir('plugins') and not os.path.exists('plugins/__init__.py'):
            with open('plugins/__init__.py', 'w') as fh:
                fh.write('# Plugin modules go here.')

    config['__colorful__'] = colorful
    config['__invariant__'] = invariant
    config['__quiet__'] = quiet
    config['__configuration_filename__'] = conf_filename
    config['__cwd__'] = original_cwd
    site = Nikola(**config)
    DN = DoitNikola(site, quiet)
    if _RETURN_DOITNIKOLA:
        return DN
    _ = DN.run(oargs)

    if site.invariant:
        freeze.stop()
    return _


class Help(DoitHelp):
    """Show Nikola usage."""

    @staticmethod
    def print_usage(cmds):
        """Print nikola "usage" (basic help) instructions."""
        # Remove 'run'.  Nikola uses 'build', though we support 'run' for
        # people used to it (eg. doit users).
        # WARNING: 'run' is the vanilla doit command, without support for
        #          --strict, --invariant and --quiet.
        del cmds['run']

        print("Nikola is a tool to create static websites and blogs. For full documentation and more information, please visit https://getnikola.com/\n\n")
        print("Available commands:")
        for cmd_name in sorted(cmds.keys()):
            cmd = cmds[cmd_name]
            print("  nikola {:20s} {}".format(cmd_name, cmd.doc_purpose))
        print("")
        print("  nikola help                 show help / reference")
        print("  nikola help <command>       show command usage")
        print("  nikola help <task-name>     show task usage")


class Build(DoitRun):
    """Expose "run" command as "build" for backwards compatibility."""

    def __init__(self, *args, **kw):
        """Initialize Build."""
        opts = list(self.cmd_options)
        opts.append(
            {
                'name': 'strict',
                'long': 'strict',
                'default': False,
                'type': bool,
                'help': "Fail on things that would normally be warnings.",
            }
        )
        opts.append(
            {
                'name': 'invariant',
                'long': 'invariant',
                'default': False,
                'type': bool,
                'help': "Generate invariant output (for testing only!).",
            }
        )
        opts.append(
            {
                'name': 'quiet',
                'long': 'quiet',
                'short': 'q',
                'default': False,
                'type': bool,
                'help': "Run quietly.",
            }
        )
        self.cmd_options = tuple(opts)
        super(Build, self).__init__(*args, **kw)


class Clean(DoitClean):
    """Clean site, including the cache directory."""

    def clean_tasks(self, tasks, dryrun):
        """Clean tasks."""
        if not dryrun and config:
            cache_folder = config.get('CACHE_FOLDER', 'cache')
            if os.path.exists(cache_folder):
                shutil.rmtree(cache_folder)
        return super(Clean, self).clean_tasks(tasks, dryrun)


# Nikola has its own "auto" commands that uses livereload.
# Expose original doit "auto" command as "doit_auto".
DoitAuto.name = 'doit_auto'


class NikolaTaskLoader(TaskLoader):
    """Nikola-specific task loader."""

    def __init__(self, nikola, quiet=False):
        """Initialize the loader."""
        self.nikola = nikola
        self.quiet = quiet

    def load_tasks(self, cmd, opt_values, pos_args):
        """Load Nikola tasks."""
        if self.quiet:
            DOIT_CONFIG = {
                'verbosity': 0,
                'reporter': 'zero',
            }
        else:
            DOIT_CONFIG = {
                'reporter': ExecutedOnlyReporter,
                'outfile': sys.stderr,
            }
        DOIT_CONFIG['default_tasks'] = ['render_site', 'post_render']
        DOIT_CONFIG.update(self.nikola._doit_config)
        try:
            tasks = generate_tasks(
                'render_site',
                self.nikola.gen_tasks('render_site', "Task", 'Group of tasks to render the site.'))
            latetasks = generate_tasks(
                'post_render',
                self.nikola.gen_tasks('post_render', "LateTask", 'Group of tasks to be executed after site is rendered.'))
            signal('initialized').send(self.nikola)
        except Exception:
            LOGGER.error('Error loading tasks. An unhandled exception occurred.')
            if self.nikola.debug or self.nikola.show_tracebacks:
                raise
            _print_exception()
            sys.exit(3)
        return tasks + latetasks, DOIT_CONFIG


class DoitNikola(DoitMain):
    """Nikola-specific implementation of DoitMain."""

    # overwite help command
    DOIT_CMDS = list(DoitMain.DOIT_CMDS) + [Help, Build, Clean, DoitAuto]
    TASK_LOADER = NikolaTaskLoader

    def __init__(self, nikola, quiet=False):
        """Initialzie DoitNikola."""
        super(DoitNikola, self).__init__()
        self.nikola = nikola
        nikola.doit = self
        self.task_loader = self.TASK_LOADER(nikola, quiet)

    def get_cmds(self):
        """Get commands."""
        # core doit commands
        cmds = DoitMain.get_cmds(self)
        # load nikola commands
        for name, cmd in self.nikola._commands.items():
            cmds[name] = cmd
        return cmds

    def run(self, cmd_args):
        """Run Nikola."""
        args = self.process_args(cmd_args)
        args = [sys_decode(arg) for arg in args]

        if len(args) == 0:
            cmd_args = ['help']
            args = ['help']

        if '--help' in args or '-h' in args:
            new_cmd_args = ['help'] + cmd_args
            new_args = ['help'] + args

            cmd_args = []
            args = []

            for arg in new_cmd_args:
                if arg not in ('--help', '-h'):
                    cmd_args.append(arg)
            for arg in new_args:
                if arg not in ('--help', '-h'):
                    args.append(arg)

        if args[0] == 'help':
            self.nikola.init_plugins(commands_only=True)
        elif args[0] == 'plugin':
            self.nikola.init_plugins(load_all=True)
        else:
            self.nikola.init_plugins()

        sub_cmds = self.get_cmds()

        if any(arg in ("--version", '-V') for arg in args):
            cmd_args = ['version']
            args = ['version']
        if args[0] not in sub_cmds.keys():
            LOGGER.error("Unknown command {0}".format(args[0]))
            sugg = defaultdict(list)
            sub_filtered = (i for i in sub_cmds.keys() if i != 'run')
            for c in sub_filtered:
                d = levenshtein(c, args[0])
                sugg[d].append(c)
            if sugg.keys():
                best_sugg = sugg[min(sugg.keys())]
                if len(best_sugg) == 1:
                    LOGGER.info('Did you mean "{}"?'.format(best_sugg[0]))
                else:
                    LOGGER.info('Did you mean "{}" or "{}"?'.format('", "'.join(best_sugg[:-1]), best_sugg[-1]))
            return 3

        if not sub_cmds[args[0]] in (Help, TabCompletion) and not isinstance(sub_cmds[args[0]], Command):
            if not self.nikola.configured:
                LOGGER.error("This command needs to run inside an "
                             "existing Nikola site.")
                return 3
        try:
            return super(DoitNikola, self).run(cmd_args)
        except Exception:
            LOGGER.error('An unhandled exception occurred.')
            if self.nikola.debug or self.nikola.show_tracebacks:
                raise
            _print_exception()
            return 1

    @staticmethod
    def print_version():
        """Print Nikola version."""
        print("Nikola v" + __version__)


def levenshtein(s1, s2):
    u"""Calculate the Levenshtein distance of two strings.

    Implementation from Wikibooks:
    https://en.wikibooks.org/w/index.php?title=Algorithm_Implementation/Strings/Levenshtein_distance&oldid=2974448#Python
    Copyright © The Wikibooks contributors (CC BY-SA/fair use citation); edited to match coding style and add an exception.
    """
    if len(s1) < len(s2):
        return levenshtein(s2, s1)

    # len(s1) >= len(s2)
    if len(s2) == 0:
        return len(s1)

    previous_row = range(len(s2) + 1)
    for i, c1 in enumerate(s1):
        current_row = [i + 1]
        for j, c2 in enumerate(s2):
            # j+1 instead of j since previous_row and current_row are one character longer than s2
            insertions = previous_row[j + 1] + 1
            deletions = current_row[j] + 1
            substitutions = previous_row[j] + (c1 != c2)
            current_row.append(min(insertions, deletions, substitutions))
        previous_row = current_row

    return previous_row[-1]


def _print_exception():
    """Print an exception in a friendlier, shorter style."""
    etype, evalue, _ = sys.exc_info()
    LOGGER.error(''.join(traceback.format_exception(etype, evalue, None, limit=0, chain=False)).strip())
    LOGGER.notice("To see more details, run Nikola in debug mode (set environment variable NIKOLA_DEBUG=1) or use NIKOLA_SHOW_TRACEBACKS=1")


if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))
