"""
Vhex package core abstract class
"""
import abc

from core.logger import log

__all__ = [
    'VxRemoteBackendCore'
]

class VxRemoteBackendCore(abc.ABC):
    r"""Represent a remote backend 'core' class.

    This class is a simple abstract class that should be used by all internal
    'backend' wich should expose some common methods and property:

    ================================== =========================================
    Property                           Description
    ================================== =========================================
      name                       (str) Backend name (for debug)
      url                        (str) Backend URL  (for internal use)
    ================================== =========================================

    ================================== =========================================
    Method                             Description
    ================================== =========================================
      find()                           find packages
      clone()                          clone a package
    ================================== =========================================
    """
    def __init__(self, url):
        self._url = url
        self._pkg_list = []

    @property
    @abc.abstractmethod
    def name(self):
        """<property> hold pacakge name"""

    @property
    @abc.abstractmethod
    def url(self):
        """<property> hold pacakge URL (or path for local package)"""

    @property
    @abc.abstractmethod
    def package_list(self):
        """<property> return the pacakge list (cached)"""

    @abc.abstractmethod
    def package_fetch_versions(self, pkg):
        """<method> pacakge version fetch (cache)"""

    @abc.abstractmethod
    def package_clone(self, pkg, prefix=None):
        """<method> package primtive """

    def package_find(self, name, version=None):
        r"""Try to find package

        This method will try to find a particular package with a specific
        version if the `version` argument is provided. Otherwise, the version
        argument can holds special version requirement if the package use a
        versionning sementic (more information in <vxsdk/core/pkg/version.py>)

        If name is empty, all package will be returned

        @args
        > names    (str) - package name
        > versions (str) - version pattern

        Return:
        > A list of dictionary with (at least):
            [
                {
                    'name'          (str) : package name
                    'full_name'     (str) : full named package (author+name)
                    'description'   (str) : package description
                    'versions'     (list) : [
                        List of :obj:VxVersion that match the `version` argument
                    ]
                },
                ...
            ]
        """
        # check if we need to return the complet list
        if not name:
            ret = []
            for pkg in self.package_list:
                if not self.package_fetch_versions(pkg):
                    continue
                pkg_cpy = pkg.copy()
                pkg_cpy['version'] = None
                ret.append(pkg_cpy)
            return ret

        # handle package name and version verification
        # @note
        # - return on the first matched package
        for pkg in self.package_list:
            # check package name
            if pkg['name'] != name:
                continue

            # fetch version information
            if not self.package_fetch_versions(pkg):
                log.warn("[pkg] '{pkg['name']}' unable to fetch versions")
                continue

            # if the version is None, we just need to fetch available
            # versions then return
            if not version:
                pkg_cpy = pkg.copy()
                pkg_cpy['version'] = None
                return [pkg_cpy]

            # perform version checking and select the best fit
            ver_found = None
            for ver in pkg['versions']:
                if not ver.validate(version):
                    continue
                if not ver_found or ver.compare(ver_found.name) < 0:
                    ver_found = ver
            if not ver_found:
                return []

            # isolate the best version
            pkg_cpy = pkg.copy()
            pkg_cpy['version'] = ver_found
            return [pkg_cpy]

        # not requested package found, return
        return None