import bottle
from bottle import jinja2_template as template, request, response

import datetime
import email
import email.policy
import functools
import glob
import hashlib
import magic
import os
import pathlib
import pygit2
import pytz
import re
import stat
import subprocess
import timeago

from pygments import highlight
from pygments.lexers import guess_lexer, guess_lexer_for_filename
from pygments.formatters import HtmlFormatter




###############################################################################
# SETTINGS
###############################################################################

# The root folder where Gitolite stores the repositories. This is used to find the
# actual repositories.
GITOLITE_REPOSITORIES_ROOT = '/home/git/repositories'

# These are only used when anonymous cloning over HTTPS
GITOLITE_SHELL = '/home/git/bin/gitolite-shell'
GITOLITE_HTTP_HOME = '/home/git'

# The domain of this instance. This is only really used when displaying list addresses,
# or when the domain needs to be displayed on some pages.
INSTANCE_DOMAIN = 'domain.local'




###############################################################################
# UTILITY FUNCTIONS
# This is code that is reused several times within the Bottle controllers
# below, so it's been grouped into functions.
###############################################################################

def list_repositories():
    """
    Scan GITOLITE_REPOSITORIES_ROOT for Git repositories, and return a list of them.
    """
    
    repositories = []
    
    # When topdown is True, the caller can modify the dirnames list in-place and
    # walk() will only recurse into the subdirectories whose names remain in dirnames;
    # this can be used to prune the search.
    # https://docs.python.org/3.12/library/os.html#os.walk
    for path, dirs, files in os.walk(GITOLITE_REPOSITORIES_ROOT, topdown=True):
        # Remove all files, we only want to recurse into directories
        files.clear()
        
        # This path is a git repo. Remove all sub-dirs because we don't need to
        # recurse any further
        if path.endswith('.git'):
            dirs.clear()
            
            repository = os.path.relpath(path, GITOLITE_REPOSITORIES_ROOT)
            
            # DO NOT LIST gitolite-admin repository!
            # This is the administration repository of this instance!
            if repository.lower() == 'gitolite-admin.git':
                continue
            
            repositories.append(repository)

    repositories.sort()
    return repositories

def parse_thread_tags(data):
    """
    Parse "tags" file of a mailing list thread.
    """
    
    tags = {}
    
    for line in data.splitlines():
        k, v = line.split('=', 1)
        k = k.strip()
        v = v.strip()
        tags[k] = tags.get(k, []) + [ v ]
    
    return tags




###############################################################################
# WEB APP
# Here below are all the Bottle routes and controllers.
###############################################################################

if not os.path.isdir(GITOLITE_REPOSITORIES_ROOT):
    print('Invalid repositories path: {}'.format(GITOLITE_REPOSITORIES_ROOT))
    exit(4)

# This only exists for exporting the bottle app object for a WSGI server such as Gunicorn
application = bottle.app()

# Directories to search for HTML templates
bottle.TEMPLATE_PATH = [ './templates' ]

def human_size(bytes, B=False):
    """
    Convert a file size in bytes to a human friendly form.
    This is only used in templates when showing file sizes.
    """
    
    for unit in [ 'B' if B else '', 'K', 'M', 'G', 'T', 'P' ]:
        if bytes < 1024: break
        bytes = bytes / 1024
    
    return '{}{}'.format(round(bytes), unit).rjust(5)

def humanct(commit_time, commit_time_offset = 0):
    """
    The following will add custom functions to the jinja2 template engine.
    These will be available to use within templates.
    """
    
    delta = datetime.timedelta(minutes=commit_time_offset)
    tz = datetime.timezone(delta)

    dt = datetime.datetime.fromtimestamp(commit_time, tz)
    
    return dt.astimezone(pytz.utc).strftime('%Y-%m-%d %H:%M:%S')
    
template = functools.partial(template, template_settings = {
    'filters': {
        'ago': timeago.format,
        'datetime': lambda date: dateutil.parser.parse(date).strftime('%b %-d, %Y - %H:%M%z%Z'),
        # Convert a file's mode to a string of the form '-rwxrwxrwx'
        'filemode': stat.filemode,
        # Human-friendly file size:
        'human_size': human_size,
    },
    'globals': {
        'commit_time': humanct,
        'instance_domain': INSTANCE_DOMAIN,
        'now': lambda: datetime.datetime.now(datetime.timezone.utc),
        'request': request,
        'url': application.get_url,
    },
    'autoescape': True
})

@bottle.error(404)
def error404(error):
    """
    Custom 404 page.
    
    :param error: bottle.HTTPError given by Bottle when calling abort(404).
    """
    
    return '[404] {}'.format(error.body)

@bottle.get('/static/<filename:path>', name='static')
def static(filename):
    """
    Path for serving static files.
    """

    return bottle.static_file(filename, root='./static/')

@bottle.get('/', name='about')
def about():
    """
    The home page displayed at https://domain/
    """
    
    return template('about.html', domain=INSTANCE_DOMAIN)

@bottle.get('/explore', name='explore')
def explore():
    """
    The home page displayed at https://domain/
    """
    
    repositories = list_repositories()
    
    return template('explore.html', repositories=repositories)

@bottle.get('/<repository:path>.git', name='readme')
def readme(repository):
    """
    Show README of the repository.
    
    :param repository: Match repository name ending with ".git"
    """
    
    repository += '.git'
    path = os.path.join(GITOLITE_REPOSITORIES_ROOT, repository)

    if not os.path.isdir(path):
        bottle.abort(404, 'No repository at this path.')
    
    repo = pygit2.Repository(path)
    local_branches = list(repo.branches.local)
    
    HEAD = None
    ref_name = None
    
    try:
        HEAD = repo.head.name
        ref_name = HEAD
    except:
        for name_candidate in [ 'master', 'main', 'trunk', 'development', 'dev' ]:
            if name_candidate in local_branches:
                ref_name = name_candidate
                break
    
    readme = ''
    
    if ref_name:
        tree = repo.revparse_single(ref_name).tree
        
        for e in tree:
            if e.name.lower() not in [ 'readme', 'readme.md', 'readme.rst' ]:
                continue
            
            if e.is_binary:
                continue
                
            # Read the README content, cut at 1MB
            readme = tree[e.name].data[:1048576].decode('UTF-8')
            break
    
    repo_size = sum(f.stat().st_size for f in pathlib.Path(path).glob("**/*"))
    
    return template('repository/readme.html',
                    readme=readme,
                    repository=repository,
                    repository_size=human_size(repo_size),
                    head_ref=HEAD)

@bottle.get('/<repository:path>.git/refs', name='refs')
def refs(repository):
    """
    List repository refs
    """
    
    repository += '.git'
    path = os.path.join(GITOLITE_REPOSITORIES_ROOT, repository)
    
    if not os.path.isdir(path):
        bottle.abort(404, 'No repository at this path.')
    
    repo = pygit2.Repository(path)
    
    if repo.is_empty:
        return template('repository/refs.html',
                        repository=repository)
    
    HEAD = None
    heads = []
    tags = []
    
    for ref in repo.references:
        if ref.startswith('refs/heads/'):
            heads.append(ref)
        if ref.startswith('refs/tags/'):
            tags.append(ref)
    
    heads.sort()
    tags.sort()
    
    try:
        HEAD = repo.head.name
    except:
        pass
    
    return template('repository/refs.html',
                    repository=repository,
                    heads=heads, tags=tags, head=HEAD)

@bottle.get('/<repository:path>.git/tree/<revision>', name='tree')
@bottle.get('/<repository:path>.git/tree/<revision>/<tree_path:path>', name='tree_path')
def tree(repository, revision, tree_path=None):
    """
    Show commit tree.
    """
    
    repository += '.git'
    repository_path = os.path.join(GITOLITE_REPOSITORIES_ROOT, repository)
    
    if not os.path.isdir(repository_path):
        bottle.abort(404, 'No repository at this path.')
    
    repo = pygit2.Repository(repository_path)
    
    if repo.is_empty:
        return template('repository/tree.html',
                        repository=repository, revision=revision)
    
    git_object = None
    
    try:
        git_object = repo.revparse_single(revision)
    except:
        pass
    
    if not git_object:
        return template('repository/tree.html',
                        repository=repository, revision=revision)
    
    # List all the references.
    # This is used for allowing the user to switch revision with a selector.
    HEAD = None
    heads = []
    tags = []
    for ref in repo.references:
        if ref.startswith('refs/heads/'): heads.append(ref)
        if ref.startswith('refs/tags/'):  tags.append(ref)
    heads.sort()
    tags.sort()
    
    try:
        HEAD = repo.head.name
    except:
        pass
    
    if git_object.type == pygit2.GIT_OBJ_TAG:
        git_object = git_object.peel(None)
    
    if git_object.type == pygit2.GIT_OBJ_COMMIT:
        git_object = git_object.tree
    
    if git_object.type == pygit2.GIT_OBJ_TREE and tree_path:
        git_object = git_object[tree_path]
    
    if git_object.type == pygit2.GIT_OBJ_TREE:
        return template(
            'repository/tree.html',
            heads=heads, head_ref=HEAD, tags=tags,
            tree=git_object,
            tree_path=tree_path,
            repository=repository, revision=revision)
    
    if git_object.type == pygit2.GIT_OBJ_BLOB:
        
        # Highlight blob text
        if git_object.is_binary:
            blob_formatted = ''
        else:
            blob_data = git_object.data.decode('UTF-8')
            
            # Guess Pygments lexer by filename, or by content if we can't find one
            try:
                pygments_lexer = guess_lexer_for_filename(git_object.name, blob_data)
            except:
                pygments_lexer = guess_lexer(blob_data)
            
            pygments_formatter = HtmlFormatter(nobackground=True, linenos=True, anchorlinenos=True,
                                           lineanchors='line')
            
            blob_formatted = highlight(blob_data, pygments_lexer, pygments_formatter)
        
        return template(
            'repository/blob.html',
            heads=heads, tags=tags,
            blob=git_object,
            blob_formatted=blob_formatted,
            repository=repository, revision=revision,
            tree_path=tree_path)
    
    bottle.abort(404)

@bottle.post('/<repository:path>.git/tree', name='tree_change')
def tree_change(repository):
    """
    Switch revision in tree page.
    This route is used by the <form> in the "tree page when changing the revision
    to be displayed.
    """
    
    revision = request.forms.get('revision')
    
    bottle.redirect(application.get_url('tree',
                                        repository=repository,
                                        revision=revision))

@bottle.get('/<repository:path>.git/log/<revision>', name='log')
def log(repository, revision):
    """
    Show commit log.
    """
    
    repository += '.git'
    repository_path = os.path.join(GITOLITE_REPOSITORIES_ROOT, repository)
    
    if not os.path.isdir(repository_path):
        bottle.abort(404, 'No repository at this path.')
    
    repo = pygit2.Repository(repository_path)
    
    if repo.is_empty:
        return template('repository/log.html',
                        repository=repository, revision=revision)
    
    git_object = None
    
    try:
        git_object = repo.revparse_single(revision)
    except:
        pass
    
    if not git_object:
        return template('repository/log.html',
                        repository=repository, revision=revision)
    
    # List all the references.
    # This is used for allowing the user to switch revision with a selector.
    HEAD = None
    heads = []
    tags = []
    for ref in repo.references:
        if ref.startswith('refs/heads/'): heads.append(ref)
        if ref.startswith('refs/tags/'):  tags.append(ref)
    heads.sort()
    tags.sort()
    
    try:
        HEAD = repo.head.name
    except:
        pass
    
    if git_object.type in [ pygit2.GIT_OBJ_TREE, pygit2.GIT_OBJ_BLOB ]:
        return 'Not a valid ref'
    
    if git_object.type == pygit2.GIT_OBJ_TAG:
        git_object = git_object.peel(None)
    
    # At this point git_object should be a valid pygit2.GIT_OBJ_COMMIT
    
    # Read 50 commits
    commits = []
    for commit in repo.walk(git_object.id):
        commits.append(commit)
        if len(commits) >= 50:
            break
    
    return template(
        'repository/log.html',
        heads=heads, head_ref=HEAD, tags=tags,
        commits=commits,
        repository=repository, revision=revision)

@bottle.get('/<repository:path>.git/raw/<revision>/<tree_path:path>', name='raw')
def raw(repository, revision, tree_path):
    """
    Return a raw blow object.
    """
    
    repository += '.git'
    repository_path = os.path.join(GITOLITE_REPOSITORIES_ROOT, repository)
    
    if not os.path.isdir(repository_path):
        bottle.abort(404, 'No repository at this path.')
    
    repo = pygit2.Repository(repository_path)
    
    if repo.is_empty:
        return ""
    
    git_tree = None
    
    try:
        git_object = repo.revparse_single(revision)
    except:
        pass
    
    if not git_object or git_object.type != pygit2.GIT_OBJ_COMMIT:
        bottle.abort(404, 'Not a valid revision.')
    
    blob = None
    
    try:
        blob = git_object.tree[tree_path]
    except:
        bottle.abort(404, 'Object does not exist.')
    
    if blob.type != pygit2.GIT_OBJ_BLOB:
        bottle.abort(404, 'Object is not a blob.')
    
    mime = magic.from_buffer(blob.data[:1048576], mime=True)
    response.content_type = mime
    return blob.data

@bottle.get('/<repository:path>.git/info/refs')
@bottle.post('/<repository:path>.git/git-upload-pack')
def git_smart_http(repository):
    """
    This controller proxies Git Smart HTTP requests to gitolite-shell for allowing
    anonymous clones over HTTP. Looks like anonymous clones are not possible via SSH,
    hence why we have this feature.
    Note that this controller only matches "git-upload-pack" (used for fetching)
    but does not match "git-receive-pack" (used for pushing). Pushing should only
    happen via SSH.
    
    Note: If CLIF is running behind a web server such as httpd or lighttpd, the
    same behavior of this controller can be achieved much more simply by configuring
    the server with CGI and an alias that redirects the URLs above to the gitolite-shell
    script. However, this controller exists so that anonymous HTTP clones can work
    "out of the box" without any manual configuration of the server.
    
    Documentation useful for understanding how this works:
      https://git-scm.com/docs/http-protocol
      https://bottlepy.org/docs/dev/async.html
      https://gitolite.com/gitolite/http.html#allowing-unauthenticated-access
    """
    
    # Environment variables for the Gitolite shell
    # TODO Gitolite gives a warning: "WARNING: Use of uninitialized value in concatenation (.) or string at /home/git/bin/gitolite-shell line 239"
    #      Looks like some non-critical env vars are missing here: REMOTE_PORT SERVER_ADDR SERVER_PORT
    gitenv = {
        **os.environ,
        
        # https://git-scm.com/docs/git-http-backend#_environment
        'PATH_INFO': request.path,
        'REMOTE_USER': 'anonymous', # This user must be set in ~/.gitolite.rc like this:
                                    # HTTP_ANON_USER => 'anonymous',
        'REMOTE_ADDR': request.remote_addr,
        'CONTENT_TYPE': request.content_type,
        'QUERY_STRING': request.query_string,
        'REQUEST_METHOD': request.method,
        'GIT_PROJECT_ROOT': GITOLITE_REPOSITORIES_ROOT,
        'GIT_HTTP_EXPORT_ALL': 'true',
        
        # Additional variables required by Gitolite
        'REQUEST_URI': request.fullpath,
        'GITOLITE_HTTP_HOME': GITOLITE_HTTP_HOME,
        'HOME': GITOLITE_HTTP_HOME,
    }
    
    # Start a Gitolite shell.
    # Do not replace .Popen() with .run() because it waits for child process to finish before returning.
    proc = subprocess.Popen(
        [ GITOLITE_SHELL ],
        env = gitenv,
        stdin = subprocess.PIPE,
        stdout = subprocess.PIPE)
        # stderr = )
    
    # Write the whole request body to Gitolite stdin.
    # Don't forget to close the pipe or it will hang!
    proc.stdin.write(request.body.read())
    proc.stdin.close()
    
    # Now we process the Gitolite response and return it to the client.
    
    # First we need to scan all the HTTP headers in the response so that we can
    # add them to the bottle response...
    for line in proc.stdout:
        line = line.decode('UTF-8').strip()

        # Empty line means no more headers
        if line == '':
            break

        header = line.split(':', 1)
        response.set_header(header[0].strip(), header[1].strip())

    # ...then we can return the rest of the Gitolite response to the client as we read it
    for line in proc.stdout:
        yield line

@bottle.get('/<repository:path>.mlist', name='threads')
def threads(repository):
    """
    List email threads.
    
    :param repository: Match repository name NOT ending with ".git"
    """
    
    # List of seletected tags, retrieved from the query string
    query_tags = { k: request.query.getall(k) for k in request.query.keys() }
    
    repository += '.mlist.git'
    path = os.path.join(GITOLITE_REPOSITORIES_ROOT, repository)
    list_address = '{}@{}'.format(repository[:-10], INSTANCE_DOMAIN)
    
    if not os.path.isdir(path):
        bottle.abort(404, 'No repository at this path.')
    
    repo = pygit2.Repository(path)
    tree = repo.revparse_single('HEAD').tree
    
    threads_list = []
    tags = {}
    
    for obj in tree:
        if obj.type != pygit2.GIT_OBJ_TREE:
            continue
        
        thread_date, thread_time, thread_id, thread_title = obj.name.split(' ', 3)
        
        thread_tags = {}
        try:
            thread_tags = parse_thread_tags(obj['tags'].data.decode('UTF-8'))
            
            # Collect tags for filters
            for k, v in thread_tags.items():
                tags[k] = tags.get(k, []) + v
        except:
            pass
        
        # Check if we should filter out this thread from the list
        keep = True
        for key in query_tags.keys():
            for value in query_tags[key]:
                if value not in thread_tags.get(key, []):
                    keep = False
                    break
            
            if not keep: break
        
        if keep:
            threads_list.append({
                'datetime': thread_date + ' ' + thread_time,
                'id': thread_id,
                'title': thread_title,
                'tags': thread_tags
            })
    
    threads_list.reverse()
    
    return template('mailing_list/emails.html', threads=threads_list,
                    list_address=list_address,
                    repository=repository,
                    tags=tags, query_tags=query_tags)

@bottle.get('/<repository:path>.mlist/<thread_id>', name='thread')
def thread(repository, thread_id):
    """
    Show a single email thread.
    """
    
    repository += '.mlist.git'
    path = os.path.join(GITOLITE_REPOSITORIES_ROOT, repository)
    list_address = '{}@{}'.format(repository[:-10], INSTANCE_DOMAIN)
    
    if not os.path.isdir(path):
        bottle.abort(404, 'No repository at this path.')
    
    repo = pygit2.Repository(path)
    head_tree = repo.revparse_single('HEAD').tree
    thread_tree = None
    
    for obj in head_tree:
        if obj.type != pygit2.GIT_OBJ_TREE:
            continue
        
        if thread_id in obj.name:
            thread_tree = obj
            break
    
    if not thread_tree:
        bottle.abort(404, 'Not a valid thread')
    
    thread_date, thread_time, thread_id, thread_title = thread_tree.name.split(' ', 3)
    thread_data = {
        'datetime': thread_date + ' ' + thread_time,
        'id': thread_id,
        'title': thread_title
    }
    
    # Read all the emails in this thread and collect some statistics on the way (for
    # displaying purposes only)
    emails = []
    participants = []
    tags = {}
    
    for obj in thread_tree:
        if obj.type != pygit2.GIT_OBJ_BLOB:
            continue
        
        if obj.name == 'tags':
            tags = parse_thread_tags(obj.data.decode('UTF-8'))
            continue
        
        if not obj.name.endswith('.email'):
            continue
        
        message = email.message_from_string(obj.data.decode('UTF-8'), policy=email.policy.default)
        
        email_data = {
            'id': message.get('message-id'),
            'id_hash': hashlib.sha256(message.get('message-id').encode('utf-8')).hexdigest()[:8],
            'from': email.utils.parseaddr(message.get('from')),
            'to': email.utils.parseaddr(message.get('to')),
            'in_reply_to': message.get('in-reply-to'),
            'sent_at': email.utils.parsedate_to_datetime(message.get('date')).astimezone(pytz.utc).strftime('%Y-%m-%d %H:%M:%S'),
            'received_at': email.utils.parsedate_to_datetime(message.get_all('received')[0].rsplit(";")[-1]).astimezone(pytz.utc).strftime('%Y-%m-%d %H:%M:%S'),
            'subject': message.get('subject'),
            'body': message.get_body(('plain',)).get_content()
        }
        
        emails.append(email_data)
        
        if email_data['from'] not in participants:
            participants.append(email_data['from'])
    
    emails.sort(key = lambda email: email['received_at'])
    
    return template('mailing_list/emails_thread.html', thread=thread_data, emails=emails,
                    participants=participants, list_address=list_address, tags=tags,
                    repository=repository)