"""Tools for document storgage."""
import os
import shutil
from warnings import warn

from xonsh.lib import subprocess
from contextlib import contextmanager

try:
    import hglib
except:
    hglib = None


def find_store(rc):
    if getattr(rc, "storename", None) is None and len(rc.stores) != 0:
        return rc.stores[0]
    for store in rc.stores:
        if store["name"] == rc.storename:
            return store
    else:
        msg = "Could not find the store {0!r}".format(rc.storename)
        raise RuntimeError(msg)


def storage_path(store, rc):
    """Computes the storage directory."""
    name, url = store["name"], store["url"]
    for db in rc.databases:
        if db["name"] == name and db["url"] == url:
            path = os.path.join(rc.builddir, "_dbs", name, store["path"])
            break
    else:
        path = os.path.join(rc.builddir, "_stores", name, store["path"])
    os.makedirs(path, exist_ok=True)
    return path


def sync_git(store, path):
    """Syncs the local documents via git."""
    storedir, _ = os.path.split(path)
    # get or update the storage
    if os.path.isdir(storedir):
        cmd = ["git", "pull"]
        cwd = storedir
    else:
        cmd = ["git", "clone", store["url"], storedir]
        cwd = None
    subprocess.check_call(cmd, cwd=cwd)


def sync_hg(store, path):
    """Syncs the local documents via hg."""
    storedir, _ = os.path.split(path)
    # get or update the storage
    if os.path.isdir(os.path.join(storedir, ".hg")):
        client = hglib.open(storedir)
        client.pull(update=True, force=True)
    else:
        # Strip off three characters for hg+
        client = hglib.clone(store["url"][3:], storedir)


def METHOD_NAME(store, path):
    """Syncs the local documents."""
    url = store["url"]
    if url.startswith("git") or url.endswith(".git"):
        sync_git(store, path)
    elif url.startswith("hg+"):
        sync_hg(store, path)
    elif not os.path.exists(os.path.expanduser(url)):
        raise ValueError("Do not know how to sync this kind of storage.")


def copydocs(store, path, rc):
    """Copies files to the staging area."""
    for doc in rc.documents:
        dst = os.path.join(path, os.path.split(doc)[1])
        if not rc.force and os.path.isfile(dst):
            raise RuntimeError(dst + " already exists!")
        shutil.copy2(doc, dst)


def push_git(store, path):
    """Pushes the local documents via git."""
    storedir, _ = os.path.split(path)
    cmd = ["git", "add", "."]
    subprocess.check_call(cmd, cwd=storedir)
    cmd = ["git", "commit", "-m", "regolith auto-store commit"]
    try:
        subprocess.check_call(cmd, cwd=storedir)
    except subprocess.CalledProcessError:
        warn("Could not git commit to " + storedir, RuntimeWarning)
        return
    cmd = ["git", "push"]
    try:
        subprocess.check_call(cmd, cwd=storedir)
    except subprocess.CalledProcessError:
        warn("Could not git push from " + storedir, RuntimeWarning)
        return


def push_hg(store, path):
    """Pushes the local documents via git."""
    storedir, _ = os.path.split(path)
    client = hglib.open(storedir)
    if len(client.status(modified=True, unknown=True, added=True)) == 0:
        return
    client.commit(message="regolith auto-commit", addremove=True)
    client.push()


def push(store, path):
    """Pushes the local documents."""
    url = store["url"]
    if url.startswith("git") or url.endswith(".git"):
        push_git(store, path)
    elif url.startswith("hg+"):
        push_hg(store, path)
    elif not os.path.exists(os.path.expanduser(url)):
        raise ValueError("Do not know how to push to this kind of storage.")


class StorageClient(object):
    """Interface to the storage system"""

    def __init__(self, rc, store, path):
        self.rc = rc
        self.store = store
        self.path = path

    def copydoc(self, doc):
        """Copies file to the staging area."""
        dst = os.path.join(self.path, os.path.split(doc)[1])
        if not self.rc.force and os.path.isfile(dst):
            raise RuntimeError(dst + " already exists!")
        shutil.copy2(doc, dst)
        return dst

    def retrieve(self, file_name):
        """Get file from the store

        Parameters
        ----------
        file_name : name of the file

        Returns
        -------
        path : str or None
            The path, if the file is not in the store None
        """
        ret = os.path.join(self.path, file_name)
        temp = (self.path + file_name).find(self.path, 1, -1)
        if os.path.exists(ret):
            return os.path.join(self.path, file_name)
        elif temp != -1:
            if os.name == "posix":
                return os.getcwd() + '/' + file_name
            else:
                return os.getcwd() + '\\' + file_name
        else:
            return None


@contextmanager
def store_client(rc):
    """Context manager for file storage
    
    Parameters
    ----------
    rc : RunControl

    Yields
    -------
    client : StorageClient
        The StorageClient instance
    """
    store = find_store(rc)
    path = storage_path(store, rc)
    METHOD_NAME(store, path)
    yield StorageClient(rc, store, path)
    push(store, path)


def main(rc):
    """Copies files into the local storage location and uploads them."""
    with store_client(rc) as sclient:
        for doc in rc.documents:
            sclient.copydoc(doc)