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

from wizard import app, command, deploy, scripts, shell, util

kib_buffer = 1024 * 30 # 30 MiB we will always leave available

def main(argv, baton):
    options, args = parse_args(argv, baton)
    if args:
        dir = args[0]
    else:
        dir = "."
    shell.drop_priviledges(dir, options.log_file)
    util.chdir(dir)
    sh = shell.Shell()
    util.set_git_env()
    use_shm = False # if you are running --continue, this is guaranteed to be False
    temp_dir = None
    try: # global try-finally for cleaning up /dev/shm if it's being used
        if options.continue_:
            temp_wc_dir = os.getcwd()
            user_commit, next_commit = open(".git/WIZARD_PARENTS", "r").read().split()
            repo = open(".git/WIZARD_REPO", "r").read()
            version = open(".git/WIZARD_UPGRADE_VERSION", "r").read()
            if not options.log_file and os.path.exists(".git/WIZARD_LOG_FILE"):
                options.log_file = open(".git/WIZARD_LOG_FILE", "r").read()
                # reload logging
                command.setup_file_logger(options.log_file, options.debug)
            logging.info("Continuing upgrade...")
            util.chdir(sh.eval("git", "config", "remote.origin.url"))
            d = deploy.Deployment(".")
            try:
                sh.call("git", "status")
                raise LocalChangesError()
            except shell.CallError:
                pass
        else:
            d = deploy.Deployment(".")
            if os.path.exists(".scripts/blacklisted"):
                reason = open(".scripts/blacklisted").read()
                print "-1 " + reason
                raise BlacklistedError(reason)
            d.verify()
            d.verifyTag(options.srv_path)
            d.verifyGit(options.srv_path)
            d.verifyConfigured()
            d.verifyVersion()
            if not options.dry_run:
                d.verifyWeb()
            repo = d.application.repository(options.srv_path)
            version = calculate_newest_version(sh, repo)
            if version == d.app_version.scripts_tag and not options.force:
                # don't log this error
                # XXX: maybe we should build this in as a flag to add
                # to exceptions w/ our exception handler
                sys.stderr.write("Traceback:\n  (n/a)\nAlreadyUpgraded\n")
                sys.exit(1)
            logging.info("Upgrading %s" % os.getcwd())
            kib_usage, kib_limit = scripts.get_quota_usage_and_limit()
            if kib_limit is not None and (kib_limit - kib_usage) < kib_buffer:
                raise QuotaTooLow
            if not options.dry_run:
                perform_pre_commit(sh)
            # If /dev/shm exists, it's a tmpfs and we can use it
            # to do a fast git merge. Don't forget to move it to
            # /tmp if it fails.
            if not options.dry_run:
                use_shm = os.path.exists("/dev/shm")
            temp_dir, temp_wc_dir = perform_tmp_clone(sh, use_shm)
            with util.ChangeDirectory(temp_wc_dir):
                sh.call("git", "remote", "add", "scripts", repo)
                sh.call("git", "fetch", "-q", "scripts")
                user_commit, next_commit = calculate_parents(sh, version)
                # save variables so that --continue will work
                # yeah yeah no trailing newline whatever
                open(".git/WIZARD_REPO", "w").write(repo)
                open(".git/WIZARD_UPGRADE_VERSION", "w").write(version)
                open(".git/WIZARD_PARENTS", "w").write("%s\n%s" % (user_commit, next_commit))
                open(".git/WIZARD_SIZE", "w").write(str(scripts.get_disk_usage()))
                if options.log_file:
                    open(".git/WIZARD_LOG_FILE", "w").write(options.log_file)
                perform_merge(sh, repo, d, version, use_shm, kib_limit and kib_limit - kib_usage or None)
        # variables: version, user_commit, next_commit, temp_wc_dir
        with util.ChangeDirectory(temp_wc_dir):
            try:
                sh.call("git", "status")
                sh.call("git", "commit", "-m", "throw-away commit")
            except shell.CallError:
                pass
            message = make_commit_message(version)
            new_tree = sh.eval("git", "rev-parse", "HEAD^{tree}")
            final_commit = sh.eval("git", "commit-tree", new_tree,
                    "-p", user_commit, "-p", next_commit, input=message, log=True)
            # a master branch may not necessarily exist if the user
            # was manually installed to an earlier version
            try:
                sh.call("git", "checkout", "-q", "-b", "master", "--")
            except shell.CallError:
                sh.call("git", "checkout", "-q", "master", "--")
            sh.call("git", "reset", "-q", "--hard", final_commit)
            # This is a quick sanity check to make sure we didn't completely
            # mess up the merge
            d.verifyVersion()
        # 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
        # Ok, now we have to do a crazy complicated dance to see if we're
        # going to have enough quota to finish what we need
        pre_size = int(open(os.path.join(temp_wc_dir, ".git/WIZARD_SIZE"), "r").read())
        post_size = scripts.get_disk_usage(temp_wc_dir)
        kib_usage, kib_limit = scripts.get_quota_usage_and_limit()
        backup = d.backup(options)
        if kib_limit is not None and (kib_limit - kib_usage) - (post_size - pre_size) / 1024 < kib_buffer:
            shutil.rmtree(os.path.join(".scripts/backups", sh.eval("wizard", "restore").splitlines()[0]))
            raise QuotaTooLow
        # XXX: frob .htaccess to make site inaccessible
        with util.IgnoreKeyboardInterrupts():
            with util.LockDirectory(".scripts-upgrade-lock"):
                # git merge (which performs a fast forward)
                sh.call("git", "pull", "-q", temp_wc_dir, "master")
                version_obj = distutils.version.LooseVersion(version.partition('-')[2])
                try:
                    # run update script
                    d.upgrade(version_obj, options)
                    d.verifyWeb()
                except app.UpgradeFailure:
                    logging.warning("Upgrade failed: rolling back")
                    perform_restore(d, backup)
                    raise
                except deploy.WebVerificationError as e:
                    logging.warning("Web verification failed: rolling back")
                    perform_restore(d, backup)
                    raise app.UpgradeVerificationFailure(e.contents)
        # XXX: frob .htaccess to make site accessible
        #       to do this, check if .htaccess changed, first.  Upgrade
        #       process might have frobbed it.  Don't be
        #       particularly worried if the segment disappeared
    finally:
        if use_shm and temp_dir and os.path.exists(temp_dir):
            shutil.rmtree(temp_dir)

def perform_restore(d, backup):
    # You don't want d.restore() because it doesn't perform
    # the file level backup
    shell.Shell().call("wizard", "restore", backup)
    try:
        d.verifyWeb()
    except deploy.WebVerificationError:
        logging.critical("Web verification failed after rollback")

def make_commit_message(version):
    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
    return message

def calculate_newest_version(sh, repo):
    # XXX: put this in Application
    return sh.eval("git", "--git-dir="+repo, "describe", "--tags", "master")

def calculate_parents(sh, version):
    user_commit = sh.eval("git", "rev-parse", "HEAD")
    next_commit = sh.eval("git", "rev-parse", version)
    return user_commit, next_commit

def perform_pre_commit(sh):
    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
    try:
        sh.call("git", "commit", "-a", "-m", message)
    except shell.CallError:
        logging.info("No changes detected")

def perform_tmp_clone(sh, use_shm):
    if use_shm:
        dir = "/dev/shm/wizard"
        if not os.path.exists(dir):
            os.mkdir(dir)
            os.chmod(dir, 0o777)
    else:
        dir = None
    temp_dir = tempfile.mkdtemp(prefix="wizard", dir=dir)
    temp_wc_dir = os.path.join(temp_dir, "repo")
    logging.info("Using temporary directory: " + temp_wc_dir)
    sh.call("git", "clone", "-q", "--shared", ".", temp_wc_dir)
    return temp_dir, temp_wc_dir

def perform_merge(sh, repo, d, version, use_shm, kib_avail):
    # Note: avail_quota == None means unlimited
    # 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", "-q", tag, "--")
        d.parametrize(".")
        for file in d.application.parametrized_files:
            try:
                sh.call("git", "add", "--", file)
            except shell.CallError:
                pass
        virtual_tree = sh.eval("git", "write-tree", log=True)
        parent_args = itertools.chain(*(["-p", p] for p in parents))
        virtual_commit = sh.eval("git", "commit-tree", virtual_tree,
                *parent_args, input="", log=True)
        sh.call("git", "reset", "--hard")
        return virtual_commit
    user_tree = sh.eval("git", "rev-parse", "HEAD^{tree}")
    base_virtual_commit = make_virtual_commit(d.app_version.scripts_tag)
    next_virtual_commit = make_virtual_commit(version, [base_virtual_commit])
    user_virtual_commit = sh.eval("git", "commit-tree", user_tree,
            "-p", base_virtual_commit, input="", log=True)
    sh.call("git", "checkout", user_virtual_commit, "--")
    d.application.prepareMerge(os.getcwd())
    sh.call("git", "commit", "--amend", "-a", "-m", "amendment")
    try:
        sh.call("git", "merge", next_virtual_commit)
    except shell.CallError as e:
        conflicts = e.stdout.count("CONFLICT") # not perfect, if there is a file named CONFLICT
        logging.info("Merge failed with these messages:\n\n" + e.stderr)
        # Run the application's specific merge resolution algorithms
        # and see if we can salvage it
        curdir = os.getcwd()
        if d.application.resolveConflicts(curdir):
            logging.info("Resolved conflicts with application specific knowledge")
            sh.call("git", "commit", "-a", "-m", "merge")
            return
        # XXX: Maybe should recalculate conflicts
        logging.info("Conflict info:\n" + sh.eval("git", "diff"))
        curdir = mv_shm_to_tmp(curdir, use_shm)
        print "%d %s" % (conflicts, curdir)
        raise MergeFailed

def mv_shm_to_tmp(curdir, use_shm):
    if not use_shm: return curdir
    # Keeping all of our autoinstalls in shared memory is
    # a recipe for disaster, so let's move them to slightly
    # less volatile storage (a temporary directory)
    os.chdir(tempfile.gettempdir())
    newdir = tempfile.mkdtemp(prefix="wizard")
    # shutil, not os; at least on Ubuntu os.move fails
    # with "[Errno 18] Invalid cross-device link"
    shutil.move(curdir, newdir)
    shutil.rmtree(os.path.dirname(curdir))
    curdir = os.path.join(newdir, "repo")
    return curdir

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.  If the merge fails,
this program will write the number of conflicts and the directory
of the conflicted working tree to stdout, separated by a space."""
    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")
    # notice trailing underscore
    parser.add_option("--continue", dest="continue_", action="store_true",
            default=False, help="Continues an upgrade that has had its merge manually "
            "resolved using the current working directory as the resolved copy.")
    parser.add_option("--force", dest="force", action="store_true",
            default=False, help="Force running upgrade even if it's already at latest version.")
    baton.push(parser, "srv_path")
    options, args = parser.parse_all(argv)
    if len(args) > 1:
        parser.error("too many arguments")
    return options, args

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

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

ERROR: The locker quota was too low to complete the autoinstall
upgrade.
"""

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

ERROR: This autoinstall is already at the latest version."""

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

ERROR: Merge failed.  Resolve the merge by cd'ing to the
temporary directory, finding conflicted files with `git status`,
resolving the files, adding them using `git add` and then
running `wizard upgrade --continue`."""

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

ERROR: Local changes occurred in the install while the merge was
being processed so that a pull would not result in a fast-forward.
The best way to resolve this is probably to attempt an upgrade again,
with git rerere to remember merge resolutions (XXX: not sure if
this actually works)."""

class BlacklistedError(Error):
    #: Reason why the autoinstall was blacklisted
    reason = None
    def __init__(self, reason):
        self.reason = reason
    def __str__(self):
        return """

ERROR: This autoinstall was manually blacklisted against errors;
if the user has not been notified of this, please send them
mail.

The reason was: %s""" % self.reason