import fnmatch
import os

import cwltool.process

import arvados.util
import arvados.collection

class CollectionFsAccess(cwltool.process.StdFsAccess):
    """Implement the cwltool FsAccess interface for Arvados Collections."""

    def __init__(self, basedir):
        super(CollectionFsAccess, self).__init__(basedir)
        self.collections = {}

    def get_collection(self, path):
        p = path.split("/")
        if p[0].startswith("keep:") and arvados.util.keep_locator_pattern.match(p[0][5:]):
            pdh = p[0][5:]
            if pdh not in self.collections:
                self.collections[pdh] = arvados.collection.CollectionReader(pdh)
            return (self.collections[pdh], "/".join(p[1:]))
        else:
            return (None, path)

    def _match(self, collection, patternsegments, parent):
        if not patternsegments:
            return []

        if not isinstance(collection, arvados.collection.RichCollectionBase):
            return []

        ret = []
        # iterate over the files and subcollections in 'collection'
        for filename in collection:
            if patternsegments[0] == '.':
                # Pattern contains something like "./foo" so just shift
                # past the "./"
                ret.extend(self._match(collection, patternsegments[1:], parent))
            elif fnmatch.fnmatch(filename, patternsegments[0]):
                cur = os.path.join(parent, filename)
                if len(patternsegments) == 1:
                    ret.append(cur)
                else:
                    ret.extend(self._match(collection[filename], patternsegments[1:], cur))
        return ret

    def glob(self, pattern):
        collection, rest = self.get_collection(pattern)
        patternsegments = rest.split("/")
        return self._match(collection, patternsegments, "keep:" + collection.manifest_locator())

    def open(self, fn, mode):
        collection, rest = self.get_collection(fn)
        if collection:
            return collection.open(rest, mode)
        else:
            return open(self._abs(fn), mode)

    def exists(self, fn):
        collection, rest = self.get_collection(fn)
        if collection:
            return collection.exists(rest)
        else:
            return os.path.exists(self._abs(fn))