#!/usr/bin/env python3

"""
Meh mail client
A dumb Python scripts that leverages notmuch, mbsync, and msmtp
to become a fully-functional extremly-opinonated mail client.
"""

# TODO Features
    # TODO Implement initial command set
    # TODO Lockfiles for write operations on mail files (mbsync, tags→maildir operations)
    # TODO OPTI Lockfile per account and process everything in parallel (if implemented, this
    # should be optional since while it may speed up the mail fetching process, its multi-threading
    # nature would cause a lot of cache flushes and be not very efficient on battery)
    # TODO Handle true character width
    # TODO IMAP IDLE watches?
    # TODO GPG
# TODO (only then) Refactor
    # TODO OOP-based
    # TODO Merge file with melConf

# DEBUG Small perf profiler
import time
perf_dict = dict()
perf_last = time.perf_counter()
def perfstep(name):
    t = time.perf_counter()
    global perf_last
    global perf_dict
    diff = t - perf_last
    if name not in perf_dict:
        perf_dict[name] = 0
    perf_dict[name] += diff
    perf_last = time.perf_counter()


import notmuch
import logging
import coloredlogs
import colorama
import datetime
import os
import progressbar
import argparse
import configparser
import base64
import shutil
import argparse
import xdg.BaseDirectory
import sys
import subprocess
import html
import re
import email.parser

perfstep("import")

ACCOUNTS = dict()
ALIASES = set()
db = None
config = None

def notmuch_new():
    close_database()
    log.info("Indexing mails")
    notmuchConfigPath = os.path.expanduser("~/.config/notmuch-config") # TODO Better
    cmd = ["notmuch", "--config", notmuchConfigPath, "new"]
    log.debug(" ".join(cmd))
    subprocess.run(cmd)

def list_folders():
    storagePath = os.path.realpath(os.path.expanduser(config["GENERAL"]["storage"]))
    folders = list()
    for account in ACCOUNTS.keys():
        storagePathAccount = os.path.join(storagePath, account)
        for root, dirs, files in os.walk(storagePathAccount):
            if "cur" not in dirs or "new" not in dirs or "tmp" not in dirs:
                continue
            assert root.startswith(storagePath)
            path = root[len(storagePath):]
            pathSplit = path.split('/')
            if pathSplit[0] == '':
                pathSplit = pathSplit[1:]
            folders.append(tuple(pathSplit))
    return folders

def open_database(write=False):
    global db
    mode = notmuch.Database.MODE.READ_WRITE if write else notmuch.Database.MODE.READ_ONLY
    if db:
        if db.mode == mode:
            return
        else:
            log.info("Current database not in required mode, closing")
            close_database()
    log.info("Opening database in mode {}".format(mode))
    dbPath = os.path.realpath(os.path.expanduser(config["GENERAL"]["storage"]))
    db = notmuch.Database(mode=mode, path=dbPath)

def close_database():
    global db
    if db:
        log.info("Closing database")
        db.close()
        db = None

def generate_aliases():
    for name in config.sections():
        if not name.islower():
            continue
        section = config[name]
        ALIASES.add(section["from"])
        if "alternatives" in section:
            for alt in section["alternatives"].split(";"):
                ALIASES.add(alt)
        ACCOUNTS[name] = section


def get_location(msg):
    path = msg.get_filename()
    path = os.path.dirname(path)
    base = db.get_path()
    assert path.startswith(base)
    path = path[len(base):]
    pathSplit = path.split('/')
    mailbox = pathSplit[1]
    assert mailbox in ACCOUNTS
    state = pathSplit[-1]
    folder = tuple(pathSplit[2:-1])
    assert state in {'cur', 'tmp', 'new'}
    return (mailbox, folder, state)

MAILBOX_COLORS = dict()

def get_mailbox_color(mailbox):
    if mailbox not in MAILBOX_COLORS:
        colorStr = config[mailbox]["color"]
        colorStr = colorStr[1:] if colorStr[0] == '#' else colorStr
        R = int(colorStr[0:2], 16)
        G = int(colorStr[2:4], 16)
        B = int(colorStr[4:6], 16)
        MAILBOX_COLORS[mailbox] = '\x1b[38;2;{};{};{}m'.format(R, G, B)
    return MAILBOX_COLORS[mailbox]

def format_date(date):
    now = datetime.datetime.now()
    midnight = datetime.datetime(year=now.year, month=now.month, day=now.day)
    if date > midnight:
        return date.strftime('%H:%M:%S')
    else:
        return date.strftime('%d/%m/%y')

WIDTH_FIXED = 31
WIDTH_RATIO_DEST_SUBJECT = 0.3
ISATTY = sys.stdout.isatty()
destWidth = None
subjectWidth = None
def compute_line_format():
    if ISATTY:
        columns, rows = shutil.get_terminal_size((80, 20))
        remain = columns - WIDTH_FIXED - 1
        global destWidth, subjectWidth
        destWidth = int(remain * WIDTH_RATIO_DEST_SUBJECT)
        subjectWidth = remain - destWidth
    else:
        destWidth = None
        subjectWidth = None

def clip_text(size, text):
    if size is None:
        return text
    l = len(text)
    if l == size:
        return text
    elif l > size:
        return text[:size-1] + '…'
    elif l < size:
        return text + " " * (size - l)


def print_msg(msg):
    if not destWidth:
        compute_line_format()

    sep = " " if ISATTY else "\t"
    line = ""
    tags = set(msg.get_tags())
    mailbox, folder, state = get_location(msg)
    if ISATTY:
        line += get_mailbox_color(mailbox)

    # UID
    uid = None
    for tag in tags:
        if tag.startswith('tuid'):
            uid = tag[4:]
    assert isUID(uid), uid
    line += uid

    # Date
    line += sep
    date = datetime.datetime.fromtimestamp(msg.get_date())
    line += format_date(date)

    # Icons
    line += sep
    def tags2col1(tag1, tag2, both, first, second, none):
        nonlocal line
        if tag1 in tags:
            if tag2 in tags:
                line += both
            else:
                line += first
        else:
            if tag2 in tags:
                line += second
            else:
                line += none

    tags2col1('spam', 'draft', '?', 'S', 'D', ' ')
    tags2col1('attachment', 'encrypted', 'E', 'A', 'E', ' ')
    tags2col1('unread', 'flagged', '!', 'U', 'F', ' ')
    tags2col1('sent', 'replied', '?', '↑', '↪', ' ')

    if 'sent' in tags:
        dest = msg.get_header("to")
    else:
        dest = msg.get_header("from")
    line += sep
    line += clip_text(destWidth, dest)

    # Subject
    line += sep
    subject = msg.get_header("subject")
    line += clip_text(subjectWidth, subject)

    if ISATTY:
        line += colorama.Style.RESET_ALL
    print(line)


def retag_msg(msg):
    mailbox, folder, state = get_location(msg)

    # Search-friendly folder name
    slugFolderList = list()
    for f, fold in [(f, folder[f]) for f in range(len(folder))]:
        if f == 0 and len(folder) > 1 and fold == "INBOX":
            continue
        slugFolderList.append(fold.upper())
    slugFolder = tuple(slugFolderList)

    tags = set(msg.get_tags())

    def tag_if(tag, condition):
        if condition and tag not in tags:
            msg.add_tag(tag)
        elif not condition and tag in tags:
            msg.remove_tag(tag)
    expeditor = extract_email(msg.get_header('from'))

    tag_if('inbox', slugFolder[0] == 'INBOX')
    tag_if('spam', slugFolder[0] == 'JUNK' or slugFolder[0] == 'SPAM')
    tag_if('deleted', slugFolder[0] == 'TRASH')
    tag_if('draft', slugFolder[0] == 'DRAFTS')
    tag_if('sent', expeditor in ALIASES)
    tag_if('unprocessed', False)

    # UID
    uid = msg.get_header("X-TUID")
    if not isUID(uid):
        # TODO Happens to sent mails but should it?k
        print(f"{msg.get_filename()} has no UID!")
        return
    uidtag = 'tuid{}'.format(uid)
    # Remove eventual others UID
    for tag in tags:
        if tag.startswith('tuid') and tag != uidtag:
            msg.remove_tag(tag)
    msg.add_tag(uidtag)



def extract_email(field):
    try:
        sta = field.index('<')
        sto = field.index('>')
        return field[sta+1:sto]
    except ValueError:
        return field

def applyMsgs(queryStr, action, *args, showProgress=False, write=False, closeDb=True, **kwargs):
    open_database(write=write)

    log.info("Querying {}".format(queryStr))
    query = notmuch.Query(db, queryStr)
    query.set_sort(notmuch.Query.SORT.OLDEST_FIRST)

    elements = query.search_messages()
    nbMsgs = query.count_messages()

    iterator = progressbar.progressbar(elements, max_value=nbMsgs) if showProgress else elements

    log.info("Executing {}".format(action))
    for msg in iterator:
        if write:
            msg.freeze()

        action(msg, *args, **kwargs)

        if write:
            msg.thaw()
            msg.tags_to_maildir_flags()

    if closeDb:
        close_database()

    return nbMsgs

def notify_msg(msg):
    log.info("Sending notification for {}".format(msg))
    subject = msg.get_header("subject")
    expd = msg.get_header("from")
    account, _, _ = get_location(msg)

    summary = '{} (<i>{}</i>)'.format(html.escape(expd), account)
    body = html.escape(subject)
    cmd = ["notify-send", "-u", "low", "-i", "mail-message-new", summary, body]
    print(' '.join(cmd))
    subprocess.run(cmd)


def notify_all(*args, **kwargs):
    open_database()
    nbMsgs = applyMsgs('tag:unread and tag:unprocessed', notify_msg)
    if nbMsgs > 0:
        log.info("Playing notification sound ({} new message(s))".format(nbMsgs))
        cmd = ["play", "-n", "synth", "sine", "E4", "sine", "A5", "remix", "1-2", "fade", "0.5", "1.2", "0.5", "2"]
        subprocess.run(cmd)
    close_database()

def isUID(uid):
    return isinstance(uid, str) and len(uid) == 12 and re.match('^[a-zA-Z0-9+/]{12}$', uid)

# From https://stackoverflow.com/a/312464
def chunks(l, n):
    """Yield successive n-sized chunks from l."""
    for i in range(0, len(l), n):
        yield l[i:i + n]

def apply_msgs_input(argmessages, action, write=False):
    if not len(argmessages):
        fromStdin = not sys.stdin.isatty()
    else:
        fromStdin = len(argmessages) == 1 and argmessages == '-'

    messages = list()
    if fromStdin:
        for line in sys.stdin:
            uid = line[:12]
            if not isUID(uid):
                log.error("Not an UID: {}".format(uid))
                continue
            messages.append(uid)
    else:
        for uids in argmessages:
            if len(uids) > 12:
                log.warn("Might have forgotten some spaces between the UIDs. Don't worry, I'll split them for you")
            for uid in chunks(uids, 12):
                if not isUID(uid):
                    log.error("Not an UID: {}".format(uid))
                    continue
                messages.append(uid)

    for message in messages:
        queryStr = 'tag:tuid{}'.format(message)
        nbMsgs = applyMsgs(queryStr, action, write=write, closeDb=False)
        if nbMsgs < 1:
            log.error("Couldn't execute function for message {}".format(message))
    close_database()

def format_header_value(val):
    return val.replace('\n', '').replace('\t', '').strip()

# From https://stackoverflow.com/a/1094933
def sizeof_fmt(num, suffix='B'):
    for unit in ['','Ki','Mi','Gi','Ti','Pi','Ei','Zi']:
        if abs(num) < 1024.0:
            return "%3.1f %s%s" % (num, unit, suffix)
        num /= 1024.0
    return "%.1f %s%s" % (num, 'Yi', suffix)

PART_MULTI_FORMAT = colorama.Fore.BLUE + '{nb} {indent}+ {typ}' + colorama.Style.RESET_ALL
PART_LEAF_FORMAT = colorama.Fore.BLUE + '{nb} {indent}→ {desc} ({typ}; {size})' + colorama.Style.RESET_ALL
def show_parts_tree(part, lvl=0, nb=1):
    indent = lvl * '\t'
    typ = part.get_content_type()
    if part.is_multipart():
        print(PART_MULTI_FORMAT.format(nb=nb, indent=indent, typ=typ))
        payl = part.get_payload()
        size = 1
        for obj in payl:
            size += show_parts_tree(obj, lvl=lvl+1, nb=nb+size)
        return size
    else:
        size = len(part.get_payload(decode=True))
        desc = part.get('Content-Description', '<no description>')
        print(PART_LEAF_FORMAT.format(nb=nb, indent=indent, typ=typ, desc=desc, size=sizeof_fmt(size)))
        return 1

INTERESTING_HEADERS = ["Date", "From", "Subject", "To", "Cc", "Message-Id"]
HEADER_FORMAT = colorama.Fore.BLUE + colorama.Style.BRIGHT + '{}:' + colorama.Style.NORMAL + ' {}' + colorama.Style.RESET_ALL
def read_msg(msg):
    # Parse
    filename = msg.get_filename()
    parser = email.parser.BytesParser()
    with open(filename, 'rb') as f:
        mail = parser.parse(f)

    # Debug
    global a
    a = mail

    # Defects
    if len(mail.defects):
        log.warn("Defects found in the mail:")
        for defect in mail.defects:
            log.warn(mail.defects)


    # Headers
    for key in INTERESTING_HEADERS:
        val = mail.get(key)
        if val:
            val = format_header_value(val)
            print(HEADER_FORMAT.format(key, val))
    # TODO Show all headers
    # TODO BONUS Highlight failed verifications

    show_parts_tree(mail)
    print()

    # Show text/plain
    for part in mail.walk():
        if part.get_content_type() == "text/plain":
            payl = part.get_payload(decode=True)
            print(payl.decode())


perfstep("definitions")

if __name__ == "__main__":
    # Main arguments
    parser = argparse.ArgumentParser(description="Meh mail client")
    selectedVerbosityLevels = ["DEBUG", "INFO", "WARNING", "ERROR", "FATAL"]
    parser.add_argument('-v', '--verbosity', choices=selectedVerbosityLevels, default='WARNING', help="Verbosity of log messages")
    # parser.add_argument('-n', '--dry-run', action='store_true', help="Don't do anything") # DEBUG
    defaultConfigFile = os.path.join(xdg.BaseDirectory.xdg_config_home, 'mel', 'accounts.conf')
    parser.add_argument('-c', '--config', default=defaultConfigFile, help="Accounts config file")

    subparsers = parser.add_subparsers(help="Action to execute")

    ## List messages

    def func_default(args):
        applyMsgs('tag:inbox', print_msg)
    parser.set_defaults(func=func_default)

    # inbox (default)
    def func_inbox(args):
        queryStr = 'tag:unread' if args.only_unread else 'tag:inbox'
        applyMsgs(queryStr, print_msg)

    parserInbox = subparsers.add_parser("inbox", help="Show unread, unsorted and flagged messages")
    parserInbox.add_argument('-u', '--only-unread', action='store_true', help="Show unread messages only")
    # TODO Make this more relevant
    parserInbox.set_defaults(func=func_inbox)


    # list folder [--recurse]
    ## List actions


    # flag msg...
    def func_flag(args):
        def flag_msg(msg):
            msg.add_tag('flagged')
        apply_msgs_input(args.message, flag_msg, write=True)
    parserFlag = subparsers.add_parser("flag", help="Mark messages as flagged")
    parserFlag.add_argument('message', nargs='*', help="Messages")
    parserFlag.set_defaults(func=func_flag)


    # unflag msg...
    def func_unflag(args):
        def unflag_msg(msg):
            msg.remove_tag('flagged')
        apply_msgs_input(args.message, unflag_msg, write=True)
    parserUnflag = subparsers.add_parser("unflag", help="Mark messages as not-flagged")
    parserUnflag.add_argument('message', nargs='*', help="Messages")
    parserUnflag.set_defaults(func=func_unflag)


    # delete msg...
    # spam msg...
    # move dest msg...
    ## Read message


    # read msg [--html] [--plain] [--browser]
    def func_read(args):
        apply_msgs_input(args.message, read_msg)
    parserRead = subparsers.add_parser("read", help="Read message")
    parserRead.add_argument('message', nargs=1, help="Messages")
    parserRead.set_defaults(func=func_read)


    # attach msg [id] [--save] (list if no id, xdg-open else)
    ## Redaction
    # new account
    # reply msg [--all]
    ## Folder management
    # tree [folder]
    # mkdir folder
    # rmdir folder (prevent if folder isn't empty (mail/subfolder))
    # (yeah that should do)
    ## Meta
    # setup (interactive thing maybe)


    # fetch (mbsync, notmuch new, retag, notify; called by greater gods)
    def func_fetch(args):
        # Fetch mails
        log.info("Fetching mails")
        mbsyncConfigPath = os.path.expanduser("~/.config/mbsyncrc") # TODO Better
        cmd = ["mbsync", "--config", mbsyncConfigPath, "--all"]
        subprocess.run(cmd)

        # Index new mails
        notmuch_new()

        # Notify
        notify_all()

        # Tag new mails
        applyMsgs('tag:unprocessed', retag_msg, showProgress=True, write=True)

    parserFetch = subparsers.add_parser("fetch", help="Fetch mail, tag them, and run notifications")
    parserFetch.set_defaults(func=func_fetch)


    ## Debug
    # debug (various)
    def func_expose(args):
        # And leave the door open
        def expose_msg(a):
            global msg
            msg = a
        applyMsgs('tag:tuidyviU45m6flff', expose_msg, closeDb=False)
    def func_debug(args):
        from pprint import pprint
        pprint(list_folders())
    parserDebug = subparsers.add_parser("debug", help="Who know what this holds...")
    parserDebug.set_defaults(verbosity='DEBUG')
    parserDebug.set_defaults(func=func_debug)

    # retag (all or unprocessed)
    def func_retag(args):
        applyMsgs('*', retag_msg, showProgress=True, write=True)
    parserRetag = subparsers.add_parser("retag", help="Retag all mails (when you changed configuration)")
    parserRetag.set_defaults(func=func_retag)

    # all
    def func_all(args):
        applyMsgs('*', print_msg)

    parserAll = subparsers.add_parser("all", help="Show ALL messages")
    parserAll.set_defaults(func=func_all)

    # Init
    args = parser.parse_args()
    perfstep("parse_args")

    colorama.init()
    coloredlogs.install(level=args.verbosity, fmt='%(levelname)s %(message)s')
    log = logging.getLogger()

    log.info("Loading config {}".format(args.config))
    if not os.path.isfile(args.config):
        log.fatal("Config file not found: {}".format(args.config))
        sys.exit(1)
        # TODO Create it, maybe?
    config = configparser.ConfigParser()
    config.read(args.config)

    generate_aliases()
    perfstep("config")

    if args.func:
        log.info("Executing function {}".format(args.func))
        args.func(args)

    perfstep("exec")

    # DEBUG
    sys.exit(0)
    for kv in sorted(perf_dict.items(), key=lambda p: p[1]):
        log.debug("{1:.6f} {0}".format(*kv))