#!/usr/local/bin/python2.7
# -*- coding: utf-8 -*-

# (c) 2012, Michael DeHaan <michael.dehaan@gmail.com>
#
# This file is part of Ansible
#
# Ansible 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 3 of the License, or
# (at your option) any later version.
#
# Ansible 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 Ansible.  If not, see <http://www.gnu.org/licenses/>.

DOCUMENTATION = '''
---
module: git
author: Michael DeHaan
version_added: 0.0.1
short_description: Deploy software (or files) from git checkouts
description:
    - Manage I(git) checkouts of repositories to deploy files or software.
options:
    repo:
        required: true
        aliases: [ name ]
        description:
            - git, SSH, or HTTP protocol address of the git repository.
    dest:
        required: true
        description:
            - Absolute path of where the repository should be checked out to.
    version:
        required: false
        default: "HEAD"
        description:
            - What version of the repository to check out.  This can be the
              git I(SHA), the literal string C(HEAD), a branch name, or a tag name.
    remote:
        required: false
        default: "origin"
        description:
            - Name of the remote branch.
    force:
        required: false
        default: "yes"
        choices: [ yes, no ]
        version_added: "0.7"
        description:
            - If C(yes), any modified files in the working
              repository will be discarded.  Prior to 0.7, this was always
              'yes' and could not be disabled.
examples:
    - code: "git: repo=git://foosball.example.org/path/to/repo.git dest=/srv/checkout version=release-0.22"
      description: Example git checkout from Ansible Playbooks
'''

import re
import tempfile

def _run(args):
    cmd = subprocess.Popen(args, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    out, err = cmd.communicate()
    rc = cmd.returncode
    return (rc, out, err)

def get_version(dest):
    ''' samples the version of the git repo '''
    os.chdir(dest)
    cmd = "git show --abbrev-commit"
    sha = os.popen(cmd).read().split("\n")
    sha = sha[0].split()[1]
    return sha

def clone(repo, dest, remote):
    ''' makes a new git repo if it does not already exist '''
    try:
        os.makedirs(os.path.dirname(dest))
    except:
        pass
    return _run("git clone -o %s %s %s" % (remote, repo, dest))

def has_local_mods(dest):
    os.chdir(dest)
    cmd = "git status -s"
    lines = os.popen(cmd).read().splitlines()
    lines = filter(lambda c: re.search('^\\?\\?.*$',c) == None,lines)
    return len(lines) > 0

def reset(module,dest,force):
    '''
    Resets the index and working tree to HEAD.
    Discards any changes to tracked files in working
    tree since that commit.
    '''
    os.chdir(dest)
    if not force and has_local_mods(dest):
        module.fail_json(msg="Local modifications exist in repository (force=no).")
    return _run("git reset --hard HEAD")

def get_branches(module, dest):
    os.chdir(dest)
    branches = []
    (rc, out, err) = _run("git branch -a")
    if rc != 0:
        module.fail_json(msg="Could not determine branch data - received %s" % out)
    for line in out.split('\n'):
        branches.append(line.strip())
    return branches

def is_remote_branch(module, dest, remote, branch):
    branches = get_branches(module, dest)
    rbranch = 'remotes/%s/%s' % (remote, branch)
    if rbranch in branches:
        return True
    else:
        return False

def is_local_branch(module, dest, branch):
    branches = get_branches(module, dest)
    lbranch = '%s' % branch
    if lbranch in branches:
        return True
    elif '* %s' % branch in branches:
        return True
    else:
        return False

def is_current_branch(module, dest, branch):
    branches = get_branches(module, dest)
    for b in branches:
        if b.startswith('* '):
            cur_branch = b
    if branch == cur_branch or '* %s' % branch == cur_branch:
        return True
    else:
        return True

def is_not_a_branch(module, dest):
    branches = get_branches(module, dest)
    for b in branches:
        if b.startswith('* ') and 'no branch' in b:
            return True
    return False

def get_head_branch(module, dest, remote):
    '''
    Determine what branch HEAD is associated with.  This is partly
    taken from lib/ansible/utils/__init__.py.  It finds the correct
    path to .git/HEAD and reads from that file the branch that HEAD is
    associated with.  In the case of a detached HEAD, this will look
    up the branch in .git/refs/remotes/<remote>/HEAD.
    '''
    repo_path = os.path.join(dest, '.git')
    # Check if the .git is a file. If it is a file, it means that we are in a submodule structure.
    if os.path.isfile(repo_path):
        try:
            gitdir = yaml.load(open(repo_path)).get('gitdir')
            # There is a posibility the .git file to have an absolute path.
            if os.path.isabs(gitdir):
                repo_path = gitdir
            else:
                repo_path = os.path.join(repo_path.split('.git')[0], gitdir)
        except (IOError, AttributeError):
            return ''
    # Read .git/HEAD for the name of the branch.
    # If we're in a detached HEAD state, look up the branch associated with
    # the remote HEAD in .git/refs/remotes/<remote>/HEAD
    f = open(os.path.join(repo_path, "HEAD"))
    if is_not_a_branch(module, dest):
        f.close()
        f = open(os.path.join(repo_path, 'refs', 'remotes', remote, 'HEAD'))
    branch = f.readline().split('/')[-1].rstrip("\n")
    f.close()
    return branch

def fetch(module, repo, dest, version, remote):
    ''' updates repo from remote sources '''
    os.chdir(dest)
    (rc, out1, err1) = _run("git fetch %s" % remote)
    if rc != 0:
        module.fail_json(msg="Failed to download remote objects and refs")

    (rc, out2, err2) = _run("git fetch --tags %s" % remote)
    if rc != 0:
        module.fail_json(msg="Failed to download remote objects and refs")
    return (rc, out1 + out2, err1 + err2)

def switch_version(module, dest, remote, version):
    ''' once pulled, switch to a particular SHA, tag, or branch '''
    os.chdir(dest)
    cmd = ''
    if version != 'HEAD':
        if not is_local_branch(module, dest, version) and is_remote_branch(module, dest, remote, version):
            cmd = "git checkout --track -b %s %s/%s" % (version, remote, version)
        else:
            cmd = "git checkout --force %s" % version
    else:
        branch = get_head_branch(module, dest, remote)
        (rc, out, err) = _run("git checkout --force %s" % branch)
        if rc != 0:
            module.fail_json(msg="Failed to checkout branch %s" % branch)
        cmd = "git reset --hard %s" % remote
    return _run(cmd)

# ===========================================

def main():
    module = AnsibleModule(
        argument_spec = dict(
            dest=dict(required=True),
            repo=dict(required=True, aliases=['name']),
            version=dict(default='HEAD'),
            remote=dict(default='origin'),
            force=dict(default='yes', choices=['yes', 'no'], aliases=['force'])
        )
    )

    dest    = os.path.expanduser(module.params['dest'])
    repo    = module.params['repo']
    version = module.params['version']
    remote  = module.params['remote']
    force   = module.boolean(module.params['force'])

    gitconfig = os.path.join(dest, '.git', 'config')

    rc, out, err, status = (0, None, None, None)

    # if there is no git configuration, do a clone operation
    # else pull and switch the version
    before = None
    local_mods = False
    if not os.path.exists(gitconfig):
        (rc, out, err) = clone(repo, dest, remote)
        if rc != 0:
            module.fail_json(msg=err)
    else:
        # else do a pull
        local_mods = has_local_mods(dest)
        before = get_version(dest)
        (rc, out, err) = reset(module,dest,force)
        if rc != 0:
            module.fail_json(msg=err)
        (rc, out, err) = fetch(module, repo, dest, version, remote)
        if rc != 0:
            module.fail_json(msg=err)

    # switch to version specified regardless of whether
    # we cloned or pulled
    (rc, out, err) = switch_version(module, dest, remote, version)
    if rc != 0:
        module.fail_json(msg=err)

    # determine if we changed anything
    after = get_version(dest)
    changed = False

    if before != after or local_mods:
        changed = True

    module.exit_json(changed=changed, before=before, after=after)

# include magic from lib/ansible/module_common.py
#<<INCLUDE_ANSIBLE_MODULE_COMMON>>
main()
