# This file is part of the Frescobaldi project, http://www.frescobaldi.org/
#
# Copyright (c) 2008 - 2012 by Wilbert Berendsen
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
# See http://www.gnu.org/licenses/ for more information.

"""
Named session support (not to be confused with the QSessionManager support
in session.py)

A session is a global list of open documents, with some additional preferences set.

"""

from __future__ import unicode_literals

import itertools

from PyQt4.QtCore import QSettings, QUrl

import app
import util


_currentSession = None


@app.aboutToQuit.connect
def _saveLastUsedSession():
    s = QSettings()
    s.beginGroup("session")
    s.setValue("lastused", _currentSession or "")
    
def loadDefaultSession():
    """Load the session which should be started by default.
    
    This can be:
    - no session,
    - last used session,
    - a specific session.
    
    Returns the document that should be set active (if any).
    """
    s = QSettings()
    s.beginGroup("session")
    start = s.value("startup", "none")
    name = None
    if start == "lastused":
        name = s.value("lastused", "")
    elif start == "custom":
        name = s.value("custom", "")
        if name not in sessionNames():
            s.setValue("startup", "none")
    if name and name in sessionNames():
        return loadSession(name)

def sessionGroup(name):
    """Returns the session settings group where settings can be stored for the named session.
    
    If the group doesn't exist, it is created.
    
    """
    session = app.settings("sessions")
    childGroups = session.childGroups()
    for group in childGroups:
        if session.value(group + "/name") == name:
            break
    else:
        for count in itertools.count(1):
            group = "session{0}".format(count)
            if group not in childGroups:
                session.setValue(group +  "/name", name)
                break
    session.beginGroup(group)
    return session

def sessionNames():
    session = app.settings("sessions")
    names = [session.value(group + "/name", "") for group in session.childGroups()]
    names.sort(key=util.naturalsort)
    return names
    
def loadSession(name):
    """Loads the given session (without closing other docs first)."""
    session = sessionGroup(name)
    
    urls = []
    for url in session.value("urls", []) or []:
        if isinstance(url, QUrl):
            urls.append(url)
    active = int(session.value("active", -1))
    result = None
    if urls:
        docs = [app.openUrl(url) for url in urls]
        if active not in range(len(docs)):
            active = 0
        result = docs[active]
    setCurrentSession(name)
    return result

def saveSession(name, documents, activeDocument=None):
    """Saves the list of documents and which one is active."""
    # only save the documents that have an url
    documents = [doc for doc in documents if not doc.url().isEmpty()]
    session = sessionGroup(name)
    session.setValue("urls", [doc.url() for doc in documents])
    if activeDocument in documents:
        session.setValue("active", documents.index(activeDocument))
    else:
        session.remove("active")
    app.saveSessionData(name)

def deleteSession(name):
    session = app.settings("sessions")
    for group in session.childGroups():
        if session.value(group + "/name", "") == name:
            session.remove(group)
            break
    if name == _currentSession:
        setCurrentSession(None)

def renameSession(old, new):
    """Renames a session."""
    session = sessionGroup(old)
    session.setValue("name", new)
    if old == currentSession():
        setCurrentSession(new)
    
def currentSession():
    return _currentSession
    
def setCurrentSession(name):
    global _currentSession
    if name != _currentSession:
        name and sessionGroup(name) # just select it, so its name is written in case it doesn't exist
        _currentSession = name
        app.sessionChanged(name)

def currentSessionGroup():
    """Returns the session settings at the current group is there is a current session.
    
    If there is no current session, returns None.
    
    """
    if _currentSession:
        return sessionGroup(_currentSession)


