#! /usr/bin/python
# -*- coding: utf8 -*-

from __future__ import absolute_import, division, print_function

import os
import sys
import stat
import errno
import logging
from tempfile import NamedTemporaryFile as ntf
from functools import wraps
import networkx as nx

from tldp.utils import execute, logtimings

logger = logging.getLogger(__name__)

preamble = '''#! /bin/bash
set -x
set -e
set -o pipefail
'''

postamble = '''
# -- end of file
'''


def depends(graph, *predecessors):
    '''decorator to be used for constructing build order graph'''
    def anon(f):
        for dep in predecessors:
            graph.add_edge(dep.__name__, f.__name__)

        @wraps(f)
        def method(self, *args, **kwargs):
            return f(self, *args, **kwargs)
        return method
    return anon


class SignatureChecker(object):

    @classmethod
    def signatureLocation(cls, f):
        f.seek(0)
        buf = f.read(1024).lower()
        for sig in cls.signatures:
            try:
                sindex = buf.index(sig.lower())
                logger.debug("YES FOUND signature %r in %s at %s; doctype %s.",
                             sig, f.name, sindex, cls)
                return sindex
            except ValueError:
                logger.debug("not found signature %r in %s for type %s",
                             sig, f.name, cls.__name__)
        return None


class BaseDoctype(object):

    def __repr__(self):
        return '<%s:%s>' % (self.__class__.__name__, self.source.stem,)

    def __init__(self, *args, **kwargs):
        self.source = kwargs.get('source', None)
        self.output = kwargs.get('output', None)
        self.config = kwargs.get('config', None)
        self.removals = list()
        assert self.source is not None
        assert self.output is not None
        assert self.config is not None

    def cleanup(self):
        if self.config.script:
            return
        stem = self.source.stem
        removals = getattr(self, 'removals', None)
        if removals:
            for fn in removals:
                logger.debug("%s cleaning up intermediate file %s", stem, fn)
                try:
                    os.unlink(fn)
                except OSError as e:
                    if e.errno is errno.ENOENT:
                        logger.error("%s missing file at cleanup %s", stem, fn)
                    else:
                        raise e

    def build_precheck(self):
        classname = self.__class__.__name__
        for tool, validator in self.required.items():
            thing = getattr(self.config, tool, None)
            logger.debug("%s, tool = %s, thing = %s", classname, tool, thing)
            if thing is None:
                logger.error("%s missing required tool %s, skipping...",
                             classname, tool)
                return False
            assert validator(thing)
        return True

    def hook_build_success(self):
        self.cleanup()

    def hook_build_failure(self):
        self.cleanup()

    def shellscript(self, script, **kwargs):
        if self.config.build:
            return self.execute_shellscript(script, **kwargs)
        elif self.config.script:
            return self.dump_shellscript(script, **kwargs)
        else:
            etext = '%s in shellscript, neither --build nor --script'
            raise Exception(etext % (self.source.stem,))

    @logtimings(logger.debug)
    def dump_shellscript(self, script, preamble=preamble, postamble=postamble):
        source = self.source
        output = self.output
        config = self.config
        s = script.format(output=output, source=source, config=config)
        print('', file=sys.stdout)
        print(s, file=sys.stdout)
        return True

    @logtimings(logger.debug)
    def execute_shellscript(self, script, preamble=preamble, postamble=postamble):
        source = self.source
        output = self.output
        config = self.config

        logdir = output.logdir
        prefix = source.doctype.__name__ + '-'

        s = script.format(output=output, source=source, config=config)
        tf = ntf(dir=logdir, prefix=prefix, suffix='.sh', delete=False)
        if preamble:
            tf.write(preamble)
        tf.write(s)
        if postamble:
            tf.write(postamble)
        tf.close()

        mode = stat.S_IXUSR | stat.S_IRUSR | stat.S_IWUSR
        os.chmod(tf.name, mode)

        cmd = [tf.name]
        result = execute(cmd, logdir=logdir)
        if result != 0:
            with open(tf.name) as f:
                for line in f:
                    logger.info("Script: %s", line.rstrip())
            return False
        return True

    @logtimings(logger.debug)
    def buildall(self):
        stem = self.source.stem
        order = nx.dag.topological_sort(self.graph)
        logger.debug("%s build order %r", self.source.stem, order)
        for dep in order:
            method = getattr(self, dep, None)
            assert method is not None
            classname = self.__class__.__name__
            logger.info("%s calling method %s.%s", stem, classname, dep)
            if not method():
                logger.error("%s reported method %s failure, skipping...",
                             stem, dep)
                return False
        return True

    @logtimings(logger.info)
    def generate(self):
        stem = self.source.stem
        classname = self.__class__.__name__

        # -- the output directory gets to prepare; must return True
        #
        # -- the processor gets to prepare; must return True
        #
        if not self.build_precheck():
            logger.warning("%s %s failed (%s), skipping to next build",
                           stem, 'build_precheck', classname)
            return False

        if not self.output.hook_prebuild():
            logger.warning("%s %s failed (%s), skipping to next build",
                           stem, 'hook_prebuild', classname)
            return False

        opwd = os.getcwd()
        os.chdir(self.output.dirname)

        # -- now, we can try to build everything; this is the BIG WORK!
        #
        result = self.buildall()

        if result:
            self.hook_build_success()  # -- processor
            self.output.hook_build_success()  # -- output document
        else:
            self.hook_build_failure()  # -- processor
            self.output.hook_build_failure()  # -- output document

        os.chdir(opwd)

        return result

#
# -- end of file