import optparse
import sys
import os
import shutil
import logging.handlers
import errno
import tempfile
import itertools

from wizard import command, deploy, shell, util

# XXX: WARNING EXPERIMENTAL DANGER DANGER WILL ROBINSON

# need errors for checking DAG integrity (if the user is on a completely
# different history tree, stuff is problems)

def main(argv, baton):
    options, args = parse_args(argv, baton)
    dir = args[0]
    command.chdir(dir)
    if not os.path.isdir(".git"):
        raise NotAutoinstallError()
    try:
        d = deploy.Deployment(".")
    except IOError as e:
        if e.errno == errno.ENOENT:
            raise NotAutoinstallError()
        else: raise e
    repo = d.application.repository(options.srv_path)
    # begin the command line process
    sh = shell.Shell()
    # setup environment
    util.set_git_env()
    # commit their changes
    if not options.dry_run:
        pre_upgrade_commit(sh)
    # perform fetch to update repository state
    sh.call("git", "fetch", repo)
    # clone their website to a temporary directory
    temp_dir = tempfile.mkdtemp(prefix="wizard")
    temp_wc_dir = os.path.join(temp_dir, "repo")
    logging.info("Using temporary directory: " + temp_wc_dir)
    sh.call("git", "clone", "--shared", ".", temp_wc_dir)
    with util.ChangeDirectory(temp_wc_dir):
        if options.dry_run:
            pre_upgrade_commit(sh)
        # reconfigure the repository path
        sh.call("git", "remote", "add", "scripts", repo)
        sh.call("git", "fetch", "scripts")
        # perform the merge
        version = sh.call("git", "--git-dir="+repo, "describe", "--tags", "master")[0].rstrip()
        user_commit = sh.call("git", "rev-parse", "HEAD")[0].rstrip()
        next_commit = sh.call("git", "rev-parse", version)[0].rstrip()
        message = "Upgraded autoinstall in %s to %s.\n\n%s" % (util.get_dir_owner(), version, util.get_git_footer())
        try:
            message += "\nUpgraded-by: " + util.get_operator_git()
        except util.NoOperatorInfo:
            pass
        try:
            # naive merge algorithm:
            # sh.call("git", "merge", "-m", message, "scripts/master")
            # crazy merge algorithm:
            def make_virtual_commit(tag, parents = []):
                """WARNING: Changes state of Git repository"""
                sh.call("git", "checkout", tag, "--")
                d.parametrize(temp_wc_dir)
                for file in d.application.parametrized_files:
                    try:
                        sh.call("git", "add", "--", file)
                    except shell.CallError:
                        pass
                virtual_tree = sh.call("git", "write-tree")[0].rstrip()
                parent_args = itertools.chain(*(["-p", p] for p in parents))
                virtual_commit = sh.call("git", "commit-tree", virtual_tree, *parent_args, input="")[0].rstrip()
                sh.call("git", "reset", "--hard")
                return virtual_commit
            user_tree = sh.call("git", "rev-parse", "HEAD^{tree}")[0].rstrip()
            base_virtual_commit = make_virtual_commit(d.app_version.pristine_tag)
            next_virtual_commit = make_virtual_commit(version, [base_virtual_commit])
            user_virtual_commit = sh.call("git", "commit-tree", user_tree, "-p", base_virtual_commit, input="")[0].rstrip()
            sh.call("git", "checkout", user_virtual_commit, "--")
            sh.call("git", "merge", next_virtual_commit) # XXX
        except shell.CallError:
            print temp_wc_dir
            raise MergeFailed
        # Make it possible to resume here
        new_tree = sh.call("git", "rev-parse", "HEAD^{tree}")[0].rstrip()
        final_commit = sh.call("git", "commit-tree", new_tree, "-p", user_commit, "-p", next_commit, input=message)[0].rstrip()
        try:
            sh.call("git", "checkout", "-b", "master", "--")
        except shell.CallError:
            sh.call("git", "checkout", "master", "--")
        sh.call("git", "reset", "--hard", final_commit)
    # Till now, all of our operations were in a tmp sandbox.
    if options.dry_run:
        logging.info("Dry run, bailing.  See results at %s" % temp_wc_dir)
        return
    # XXX: frob .htaccess to make site inaccessible
    # git merge (which performs a fast forward)
    #   - merge could fail (race)
    sh.call("git", "pull", temp_wc_dir, "master")
    # run update script
    sh.call(".scripts/update")
    # XXX: frob .htaccess to make site accessible
    # XXX:  - check if .htaccess changed, first.  Upgrade
    #       process might have frobbed it.  Don't be
    #       particularly worried if the segment dissappeared

def pre_upgrade_commit(sh):
    try:
        message = "Pre-commit of %s locker before autoinstall upgrade.\n\n%s" % (util.get_dir_owner(), util.get_git_footer())
        try:
            message += "\nPre-commit-by: " + util.get_operator_git()
        except util.NoOperatorInfo:
            pass
        sh.call("git", "commit", "-a", "-m", message)
    except shell.CallError:
        logging.info("No changes detected")
        pass

def parse_args(argv, baton):
    usage = """usage: %prog upgrade [ARGS] DIR

Upgrades an autoinstall to the latest version.  This involves
updating files and running .scripts/update.

WARNING: This is still experimental."""
    parser = command.WizardOptionParser(usage)
    parser.add_option("--dry-run", dest="dry_run", action="store_true",
            default=False, help="Prints would would be run without changing anything")
    baton.push(parser, "srv_path")
    options, args = parser.parse_all(argv)
    if len(args) > 1:
        parser.error("too many arguments")
    elif not args:
        parser.error("must specify directory")
    return options, args

class Error(command.Error):
    """Base exception for all exceptions raised by upgrade"""
    pass

class NotAutoinstallError(Error):
    def __str__(self):
        return """

ERROR: Could not find .git file. Are you sure
this is an autoinstalled application? Did you remember
to migrate it?
"""

class MergeFailed(Error):
    def __str__(self):
        return """

ERROR: Merge failed.  Change directory to the temporary
directory and manually resolve the merge.
"""