#!/bin/python3

import os
import subprocess
import blessed
import re
import time
import sys
import io
import fileinput

from utils import utils
from config.config import *

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 edit_existing_post(args):
    selector = utils.PostSelector(blessed.Terminal(), utils.list_posts())
    selection = selector.select()
    if selection:
        print(selection)
        edit_post_with_editor(selection)
    else:
        return 1


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)