# -*- coding: utf-8 -*-
from __future__ import unicode_literals

import six

"""
    Main function:

        parse_job_list(tokens, context)

    Canonical forms:
        [A] except [B]     =>   A minus the elements in B
        [A] in [B]         =>   intersection of A and B

    Rewriting:
        not [job_list]     =>   $all except [job_list]
        except [job_list]  =>   $all except [job_list]

    Association:

        [A] except [B] except [C] == [A] except ([B] except [C])
        [A] in [B] in [C] == [A] in ([B] in [C])

    Priority:
        in > except > not



"""
import types
from collections import namedtuple

from compmake.constants import CompmakeConstants
from compmake.context import Context
from compmake.jobs.uptodate import CacheQueryDB
from contracts import check_isinstance, contract

from .. import get_job
from ...exceptions import CompmakeSyntaxError, UserError
from ...structures import Cache
from ...utils import expand_wildcard

__all__ = [
    'parse_job_list',
]

CompmakeConstants.aliases['last'] = '*'


def add_alias(alias, value):
    """ Sets the given alias to value. See eval_alias() for a discussion
    of the meaning of value. """
    CompmakeConstants.aliases[alias] = value


def assert_list_of_strings(l):
    assert all([isinstance(x, six.string_types) for x in l]), \
        'Expected list of strings: %s.' % str(l)


def is_alias(alias):
    return alias.lower() in CompmakeConstants.aliases


@contract(context=Context, cq=CacheQueryDB)
def eval_alias(alias, context, cq):
    """
    Evaluates the given alias.
    Returns a list of job_id strings.

    The value can have several types:
    - if it is a string, it is interpreted as a job id
    - if it is a list, it must be a list of string, interpreted as a job id
    - if it is callable (FunctionType),
      it is called, and it must return a list of strings.

    """

    alias = alias.lower()
    assert is_alias(alias)
    value = CompmakeConstants.aliases[alias]

    if isinstance(value, six.string_types):
        return list([value])
    elif isinstance(value, list):
        assert_list_of_strings(value)
        return value
    elif isinstance(value, types.FunctionType):
        result = value(context=context, cq=cq)
        # can be generator; no assert_list_of_strings(result)
        return result
    else:
        msg = 'I cannot interpret alias "%s" -> "%s".' % (alias, value)
        raise ValueError(msg)


@contract(context=Context, cq=CacheQueryDB)
def list_matching_functions(token, context, cq):
    db = context.get_compmake_db()
    assert token.endswith('()')
    if len(token) < 3:
        raise UserError('Malformed token "%s".' % token)

    function_id = token[:-2]

    num_matches = 0
    for job_id in cq.all_jobs():
        # command name (f.__name__)
        command_desc = get_job(job_id, db=db).command_desc
        if function_id.lower() == command_desc.lower():
            yield job_id
            num_matches += 1

    if num_matches == 0:
        raise UserError('Could not find matches for function "%s()".' %
                        function_id)


def expand_job_list_token(token, context, cq):
    """ Parses a token (string). Returns a generator of jobs.
        Raises UserError, CompmakeSyntaxError """

    assert isinstance(token, six.string_types)

    if token.find('*') > -1:
        return expand_wildcard(token, cq.all_jobs())
    elif is_alias(token):
        return eval_alias(token, context, cq)
    elif token.endswith('()'):
        return list_matching_functions(token, context, cq)
    else:
        # interpret as a job id
        job_id = token
        if not cq.job_exists(job_id):
            msg = 'Job or expression "%s" not found.' % job_id
            raise UserError(msg)
        return [job_id]


def expand_job_list_tokens(tokens, context, cq):
    """ Expands a list of tokens using expand_job_list_token().
        yields job_id """
    for token in tokens:
        if not isinstance(token, six.string_types):
            # print tokens XXX
            pass
        for job in expand_job_list_token(token, context, cq):
            yield job


class Operators(object):
    Op = namedtuple('Op', 'name')

    NOT = Op('not')
    DIFFERENCE = Op('difference')
    INTERSECTION = Op('intersection')

    translation = {
        'not': NOT,
        'except': DIFFERENCE,
        'but': DIFFERENCE,
        'in': INTERSECTION,
        'and': INTERSECTION,
        'intersect': INTERSECTION
    }

    @staticmethod
    def parse(tokens):
        """ Parses a list of tokens for known operators.
        Returns a list where the operators are replaced by their codes. """

        def token2op(token):
            """ Translates one token, or returns the same """
            tokenl = token.lower()
            return Operators.translation.get(tokenl, token)

        return list(map(token2op, tokens))


def list_jobs_with_state(state, context, cq):  # @UnusedVariable
    """ Returns a list of jobs in the given state. """
    for job_id in cq.all_jobs():
        if cq.get_job_cache(job_id).state == state:  # TODO
            yield job_id


def list_ready_jobs(context, cq):  # @UnusedVariable
    """ Returns a list of jobs that can be done now,
        as their dependencies are up-to-date. """
    for job_id in cq.all_jobs():
        if cq.dependencies_up_to_date(job_id):
            yield job_id


def list_uptodate_jobs(context, cq):  # @UnusedVariable
    """ Returns a list of jobs that are uptodate
        (DONE, and all depednencies DONE)."""
    for job_id in cq.all_jobs():
        up, _, _ = cq.up_to_date(job_id)
        if up:
            yield job_id


def list_todo_jobs(context, cq):  # @UnusedVariable
    """
        Returns a list of jobs that haven't been DONE.
        Note that it could be DONE but not up-to-date.
    """
    for job_id in cq.all_jobs():
        if cq.get_job_cache(job_id).state != Cache.DONE:
            yield job_id


def list_root_jobs(context, cq):  # @UnusedVariable
    """ Returns a list of jobs that were defined by the original process.  """
    for job_id in cq.all_jobs():
        job = cq.get_job(job_id)
        if is_root_job(job):
            yield job_id


def list_generated_jobs(context, cq):  # @UnusedVariable
    """ Returns a list of jobs that were generated by other jobs.  """
    for job_id in cq.all_jobs():
        job = cq.get_job(job_id)
        if not is_root_job(job):
            yield job_id


def list_levelX_jobs(context, cq, X):  # @UnusedVariable
    """ Returns a list of jobs that are at level X """
    for job_id in cq.all_jobs():
        job = cq.get_job(job_id)
        level = len(job.defined_by) - 1
        if level == X:
            yield job_id


def list_level1_jobs(context, cq):
    for x in list_levelX_jobs(context, cq, 1):
        yield x


def list_level2_jobs(context, cq):
    for x in list_levelX_jobs(context, cq, 2):
        yield x


def list_level3_jobs(context, cq):
    for x in list_levelX_jobs(context, cq, 3):
        yield x


def list_level4_jobs(context, cq):
    for x in list_levelX_jobs(context, cq, 4):
        yield x


def is_root_job(job):
    return job.defined_by == ['root']


def is_dynamic_job(job):
    return bool(job.needs_context)


def list_dynamic_jobs(context, cq):  # @UnusedVariable
    """ Returns a list of jobs that are uptodate
        (DONE, and all depednencies DONE)."""
    for job_id in cq.all_jobs():
        job = cq.get_job(job_id)
        if is_dynamic_job(job):
            yield job_id


def list_top_jobs(context, cq):  # @UnusedVariable
    """ Returns a list of jobs that are top-level targets.  """
    for job_id in cq.all_jobs():
        if not cq.direct_parents(job_id):
            yield job_id


def list_bottom_jobs(context, cq):  # @UnusedVariable
    """ Returns a list of jobs that do not depend on anything else. """
    for job_id in cq.all_jobs():
        if not cq.direct_children(job_id):  # TODO
            yield job_id


def obtain_all(context, cq):
    res = list(cq.all_jobs())
    print('obtain all: %s' % res)
    return res


add_alias('all', obtain_all)
add_alias('failed', lambda context, cq: list_jobs_with_state(Cache.FAILED,
                                                             context=context,
                                                             cq=cq))
add_alias('blocked', lambda context, cq: list_jobs_with_state(Cache.BLOCKED,
                                                              context=context,
                                                              cq=cq))
add_alias('ready', list_ready_jobs)
add_alias('todo', list_todo_jobs)
add_alias('top', list_top_jobs)
add_alias('uptodate', list_uptodate_jobs)
add_alias('root', list_root_jobs)
add_alias('generated', list_generated_jobs)
add_alias('level1', list_level1_jobs)
add_alias('level2', list_level2_jobs)
add_alias('level3', list_level3_jobs)
add_alias('level4', list_level4_jobs)
add_alias('dynamic', list_dynamic_jobs)
add_alias('bottom', list_bottom_jobs)
add_alias('done',
          lambda context, cq:
          list_jobs_with_state(Cache.DONE, context=context, cq=cq))
# add_alias('in_progress',
#           lambda context, cq: 
#           list_jobs_with_state(Cache.IN_PROGRESS, context=context, cq=cq))
add_alias('not_started',
          lambda context, cq:
          list_jobs_with_state(Cache.NOT_STARTED, context=context, cq=cq))


def parse_job_list(tokens, context, cq=None):
    """
        Parses a job list. tokens can be:

        1. a string, in that case it is split()
        2. a list, in which case each element is treated as a token.

        NO(If tokens is not empty, then if it evaluates to empty,
        an error is raised (e.g. "make failed" and no failed jobs will
        throw an error).)

        Returns a list of strings.
    """
    if cq is None:
        cq = CacheQueryDB(context.get_compmake_db())

    if isinstance(tokens, six.string_types):
        tokens = tokens.strip().split()

    if not tokens:
        return []

    # First we look for operators 
    ops = Operators.parse(tokens)

    # print(" %s => %s" % (tokens, ops))
    result = eval_ops(ops=ops, context=context, cq=cq)

    # FIXME, remove
    result = list(result)
    # print " %s => %s" % (tokens, result)

    return result


@contract(context=Context, cq=CacheQueryDB)
def eval_ops(ops, context, cq):
    """ Evaluates an expression.
      ops: list of strings and int representing operators """
    check_isinstance(ops, list)

    def list_split(l, index):
        """ Splits a list in two """
        return l[0:index], l[index + 1:]

    # The sequence of the following operations
    # defines the associativity rules

    # in > except > not 

    if Operators.INTERSECTION in ops:
        left, right = list_split(ops, ops.index(Operators.INTERSECTION))
        if not left or not right:
            msg = ''' INTERSECTION requires only a right argument.
            Interpreting "%s" INTERSECTION "%s". ''' % (
                ' '.join(left), ' '.join(right))
            raise CompmakeSyntaxError(msg)
        left = eval_ops(ops=left, context=context, cq=cq)
        right = set(eval_ops(ops=right, context=context, cq=cq))
        for x in left:
            if x in right:
                yield x

    elif Operators.DIFFERENCE in ops:
        left, right = list_split(ops, ops.index(Operators.DIFFERENCE))
        if not left or not right:
            msg = ''' EXCEPT requires a left and right argument.
            Interpreting "%s" EXCEPT "%s". ''' % (
                ' '.join(left), ' '.join(right))
            raise CompmakeSyntaxError(msg)

        left = eval_ops(ops=left, context=context, cq=cq)
        right = set(eval_ops(ops=right, context=context, cq=cq))
        for x in left:
            if x not in right:
                yield x

    elif Operators.NOT in ops:
        left, right = list_split(ops, ops.index(Operators.NOT))
        if left or not right:  # forbid left, require right
            msg = (
                    ''' NOT requires only a right argument. Interpreting "%s" NOT
                    "%s". ''' %
                    (' '.join(left), ' '.join(right)))
            raise CompmakeSyntaxError(msg)

        right_res = set(eval_ops(ops=right, context=context, cq=cq))
        # if not all_jobs:
        # assert False
        # print("NOT")
        #         print(' all_jobs evalatued to %r' % (all_jobs))
        #         print(' right ops %r evalatued to %r' % (right, right_res))
        #         result = []
        for x in cq.all_jobs():
            if not x in right_res:
                yield x
                #
                #             in_right = x in right_res
                #             print('   is %r in not set -> %s' % (x,
                # in_right))
                #             if not in_right:
                #                 result.append(x)
                #         print(' result -> %s' % result)
                #         for x in result:
                #             yield x

    else:
        # no operators: simple list
        # cannot do this anymore, now it's a generator. 
        # assert_list_of_strings(ops)
        for x in expand_job_list_tokens(ops, context=context, cq=cq):
            yield x
