#/bin/python3

import os
import subprocess

import sys

import re
import io
import fileinput

import time

import signal

from config.config import *

from utils import utils

from generators import generators


def generate(args):
    """Wrapper for generate_blog(fresh=False)."""
    # pylint: disable=unused-argument
    exit(generators.generate_blog(fresh=False))


def regenerate(args):
    """Wrapper for generate_blog(fresh=True)."""
    # pylint: disable=unused-argument
    exit(generators.generate_blog(fresh=True))


def edit_post_with_editor(path):
    """Launch text editor to edit post at a given path.

    Text editor is $VISUAL, then if empty, $EDITOR, then if still empty,
    vi.

    """
    if "VISUAL" in os.environ:
        editor = os.environ["VISUAL"]
    elif "EDITOR" in os.environ:
        editor = os.environ["EDITOR"]
    else:
        editor = "vi"
    subprocess.call([editor, path])


def new_post(title):
    """Create a new post with metadata pre-filled.

    The path to the new post is printed to stdout.

    Returns
    -------
    0
        On success.

    """
    date = utils.current_datetime()
    filename_date = date.strftime("%Y-%m-%d")
    iso_date = date.isoformat()
    display_date = "%s %d, %d" % (date.strftime("%B"), date.day, date.year)
    title_sanitized = utils.sanitize(title)
    filename = "%s-%s.md" % (filename_date, title_sanitized)
    fullpath = os.path.join(POSTSDIR, filename)
    if not os.path.isdir(POSTSDIR):
        if os.path.exists(POSTSDIR):
            os.remove(POSTSDIR)
        os.mkdir(POSTSDIR, mode=0o755)
    if os.path.exists(fullpath):
        sys.stderr.write("%serror: '%s' already exists, please pick a different title%s\n" %
                         (RED, fullpath, RESET))
        return 1
    with open(fullpath, 'w', encoding='utf-8') as newpost:
        newpost.write("---\n")
        newpost.write('title: "%s"\n' % title)
        newpost.write("date: %s\n" % iso_date)
        newpost.write("date_display: %s\n" % display_date)
        newpost.write("---\n\n")
    sys.stderr.write("New post created in:\n")
    print(fullpath)
    edit_post_with_editor(fullpath)

    return 0


def new_post_cli(args):
    """CLI wrapper around new_post."""
    new_post(args.title)


def touch(filename):
    """Update the timestamp of a post to the current time."""
    filename = os.path.basename(filename)
    fullpath = os.path.join(POSTSDIR, filename)
    if not os.path.exists(fullpath):
        sys.stderr.write("%serror: post %s not found %s\n" %
                         (RED, fullpath, RESET))
        return 1
    filename_prefix_re = re.compile(r"^[0-9]{4}-[0-9]{2}-[0-9]{2}")
    if not filename_prefix_re.match(filename):
        sys.stderr.write(RED)
        sys.stderr.write("error: post %s is not a valid post\n" % filename)
        sys.stderr.write("error: the filename of a valid post begins with "
                         "a date in the form xxxx-xx-xx\n")
        sys.stderr.write(RESET)
        return 1

    # update timestamp in the metadata section of the post
    whatchanged = io.StringIO()
    date = utils.current_datetime()
    iso_date = date.isoformat()
    display_date = "%s %d, %d" % (date.strftime("%B"), date.day, date.year)
    filename_date = date.strftime("%Y-%m-%d")
    with fileinput.input(files=(fullpath), inplace=True) as lines:
        meta_fences = 0
        for line in lines:
            if line.startswith("---"):
                meta_fences += 1
                sys.stdout.write(line)
                continue
            if meta_fences >= 2:
                # already went past the metadata section
                sys.stdout.write(line)
                continue

            if line.startswith("date: "):
                updated_line = "date: %s\n" % iso_date
                sys.stdout.write(updated_line)
                whatchanged.write("-%s+%s\n" % (line, updated_line))
                continue

            if line.startswith("date_display: "):
                updated_line = "date_display: %s\n" % display_date
                sys.stdout.write(updated_line)
                whatchanged.write("-%s+%s\n" % (line, updated_line))
                continue

            sys.stdout.write(line)

    sys.stderr.write("\n%schangeset:%s\n\n%s" %
                     (YELLOW, RESET, whatchanged.getvalue()))
    whatchanged.close()

    # check if the file needs to be renamed
    new_filename = filename_prefix_re.sub(filename_date, filename)
    if new_filename != filename:
        new_fullpath = os.path.join(POSTSDIR, new_filename)
        os.rename(fullpath, new_fullpath)
        sys.stderr.write("%srenamed to %s%s\n" % (YELLOW, new_filename, RESET))
    return 0


def touch_cli(args):
    """CLI wrapper around touch."""
    touch(args.filename)


def deploy(args):
    """Deploys build directory to origin/master without regenerating.

    Returns
    -------
    0
        On success. Exit early with nonzero status otherwise.

    """

    # pylint: disable=unused-argument,too-many-statements

    # check whether root is dirty
    os.chdir(ROOTDIR)
    dirty = subprocess.check_output(["git", "status", "--porcelain"])
    if dirty:
        sys.stderr.write(YELLOW)
        sys.stderr.write("Project root is dirty.\n")
        sys.stderr.write("You may want to commit in your changes "
                         "to the source branch, since the SHA and title "
                         "of the latest commit on the source branch will be "
                         "incorporated into the commit message on "
                         "the deployment branch. Type s[hell] on the "
                         "next prompt to open an interactive shell.\n")
        sys.stderr.write(RESET)
        while True:
            sys.stderr.write("Continue? [yNs] ")
            answer = input()
            if not answer:
                # default
                abort = True
                break
            elif answer.startswith(('y', 'Y')):
                abort = False
                break
            elif answer.startswith(('n', 'N')):
                abort = True
                break
            elif answer.startswith(('s', 'S')):
                shell = (os.environ['SHELL'] if 'SHELL' in os.environ and os.environ['SHELL']
                         else 'zsh')
                subprocess.call(shell)
                stilldirty = subprocess.check_output(["git", "status", "--porcelain"])
                if stilldirty:
                    sys.stderr.write(YELLOW)
                    sys.stderr.write("Project root is still dirty.\n")
                    sys.stderr.write(RESET)
            else:
                sys.stderr.write("Please answer yes or no.\n")
        if abort:
            sys.stderr.write("%saborting deployment%s\n" % (RED, RESET))
            return 1

    # extract latest commit on the source branch
    source_commit = subprocess.check_output(
        ["git", "log", "-1", "--pretty=oneline", "source", "--"]).decode('utf-8').strip()

    # cd into BUILDDIR and assemble commit message
    sys.stderr.write("%scommand: cd '%s'%s\n" % (BLUE, BUILDDIR, RESET))
    os.chdir(BUILDDIR)

    # extract updated time from atom.xml
    if not os.path.exists("atom.xml"):
        sys.stderr.write("atom.xml not found, cannot deploy\naborting\n")
        return 1
    atomxml = ET.parse("atom.xml").getroot()
    updated = atomxml.find('{http://www.w3.org/2005/Atom}updated').text

    commit_message = ("Site updated at %s\n\nsource branch was at:\n%s\n" %
                      (updated, source_commit))

    # commit changes in BUILDDIR
    sys.stderr.write("%scommand: git add --all%s\n" % (BLUE, RESET))
    subprocess.check_call(["git", "add", "--all"])
    sys.stderr.write("%scommand: git commit --no-verify --gpg-sign --message='%s'%s\n" %
                     (BLUE, commit_message, RESET))
    try:
        subprocess.check_call(["git", "commit", "--gpg-sign",
                               "--message=%s" % commit_message])
    except subprocess.CalledProcessError:
        sys.stderr.write("\n%serror: git commit failed%s\n" % (RED, RESET))
        return 1

    # check dirty status
    dirty = subprocess.check_output(["git", "status", "--porcelain"])
    if dirty:
        sys.stderr.write(RED)
        sys.stderr.write("error: failed to commit all changes; "
                         "build directory still dirty\n")
        sys.stderr.write("error: please manually inspect what was left out\n")
        sys.stderr.write(RESET)
        return 1

    # push to origin/master
    sys.stderr.write("%scommand: git push origin master%s\n" % (BLUE, RESET))
    try:
        subprocess.check_call(["git", "push", "origin", "master"])
    except subprocess.CalledProcessError:
        sys.stderr.write("\n%serror: git push failed%s\n" % (RED, RESET))
        return 1
    return 0


def gen_deploy(args):
    """Regenerate and deploy."""
    # pylint: disable=unused-argument,too-many-branches

    # try to smartly determine the latest post, and prompt to touch it
    current_time = time.time()
    latest_post = None
    latest_postdate = 0
    latest_mtime = 0
    for name in os.listdir(POSTSDIR):
        matchobj = re.match(r"^([0-9]{4})-([0-9]{2})-([0-9]{2})-.*\.md", name)
        if not matchobj:
            continue
        fullpath = os.path.join(POSTSDIR, name)
        mtime = os.path.getmtime(fullpath)
        # get post date from the date metadata field of the post
        postdate = 0
        with open(fullpath) as postobj:
            for line in postobj:
                dateregex = r"^date: (\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}-\d{2}:?\d{2})"
                datematch = re.match(dateregex, line.rstrip())
                if datematch:
                    postdate = dateutil.parser.parse(datematch.group(1)).timestamp()
                    break
        # skip the post if it is dated more than three days ago
        if current_time - postdate > 3 * 24 * 3600:
            continue
        if mtime > latest_mtime:
            latest_post = name
            latest_postdate = postdate
            latest_mtime = mtime
    # prompt for touching if the latest post determined above was
    # modified within the last hour but the date registered in the post
    # isn't within the last ten minutes
    if ((latest_post is not None and current_time - latest_mtime < 3600 and
         current_time - latest_postdate > 600)):
        sys.stderr.write("%sIt appears that %s might be a new post.\n"
                         "Do you want to touch its timestamp?%s\n" %
                         (GREEN, latest_post, RESET))
        while True:
            yesnoquit = input("[ynq]: ")
            if yesnoquit.startswith(("Y", "y")):
                yesno = True
                break
            elif yesnoquit.startswith(("N", "n")):
                yesno = False
                break
            elif yesnoquit.startswith(("Q", "q")):
                sys.stderr.write("%saborting gen_deploy%s\n" % (RED, RESET))
                return 1
            else:
                sys.stderr.write("Please answer yes, no, or quit.\n")
        if yesno:
            sys.stderr.write("%stouching %s%s\n" % (BLUE, latest_post, RESET))
            touch(latest_post)
            sys.stderr.write("\n")

    generators.generate_blog(fresh=True)
    deploy(None)


def preview(args):
    """Serve the blog and auto regenerate upon changes."""

    # pylint: disable=unused-argument

    server_process = utils.HTTPServerProcess(BUILDDIR)
    server_process.start()
    sys.stderr.write("watching for changes\n")
    sys.stderr.write("send SIGINT to stop\n")

    # install a SIGINT handler only for this process
    sigint_raised = False

    def sigint_mitigator(signum, frame):
        """Translate SIGINT to setting the sigint_raised flag."""
        nonlocal sigint_raised
        sigint_raised = True

    signal.signal(signal.SIGINT, sigint_mitigator)

    # Watch and auto-regen.
    # No need to actually implement watch separately, since
    # generate_blog(fresh=False, report_total_errors=False) already
    # watches for modifications and only regens upon changes, and it is
    # completely silent when there's no change.
    while not sigint_raised:
        generators.generate_blog(fresh=False, report_total_errors=False)
        time.sleep(0.5)

    sys.stderr.write("\nSIGINT received, cleaning up...\n")
    server_process.join()
    return 0