#!/usr/bin/env python3
"""Read mu4e information via D-Bus.

A little script to interpret the information from D-Bus and print it.

Requires the 'dbus-next' package and Emacs with a running mu4e, with
'mu4e-dbus-mode' enabled.

For now, two output formats are available:

1) "dump"   -> dump the information (default)
2) "waybar" -> write out json, to be used by "Waybar"
    (https://github.com/alexays/waybar)

For waybar, you could add something like the following to your
"config.jsonc" (update the "exec" path as needed):

   "custom/mu4e": {
      "exec": "~/src/mu/contrib/mu4e-dbus-client --format waybar",
      "return-type": "json",
      "interval": 120,
      "format": "{text}{icon}",
      "format-icons": {
        "empty": "📭",
        "unread": "📬",
        "new": "📧"
       },
      "tooltip" : true
     }
"""

import argparse
import json

from typing import Callable

import asyncio
import sys
from dbus_next.aio import MessageBus
from dbus_next import Variant

SERVICE = "nl.djcbsoftware.Mu4e"
OBJECT_PATH = "/nl/djcbsoftware/Mu4e"
INTERFACE = "nl.djcbsoftware.Mu4e"
PROPS_INTERFACE = "org.freedesktop.DBus.Properties"

async def get_all_properties():
    """Connect to mu4e's D-Bus service and read all properties."""
    bus = await MessageBus().connect()

    introspection = await bus.introspect(SERVICE, OBJECT_PATH)
    proxy = bus.get_proxy_object(SERVICE, OBJECT_PATH, introspection)
    props = proxy.get_interface(PROPS_INTERFACE)

    all_props = await props.call_get_all(INTERFACE)

    return all_props

def unpack_variant(val):
    """Recursively unpack D-Bus Variant types."""
    if isinstance(val, Variant):
        return unpack_variant(val.value)
    if isinstance(val, list):
        return [unpack_variant(v) for v in val]
    if isinstance(val, dict):
        return {k: unpack_variant(v) for k, v in val.items()}
    return val

def print_query_info(query_items: dict):
    """Pretty-print the QueryInfo array of dicts."""
    for i, item in enumerate(query_items):
        print(f"\n  [{i}]")
        for key, val in sorted(item.items()):
            print(f"    {key}: {val}")

def output_dump(props: dict):
    """Dump the information acquired from dbus/mu4e."""
    for key in ("Version", "DatabasePath", "RootMaildir", "Context"):
        if key in props:
            print(f"{key}: {props[key]}")

    print(f"{props}")

    if "QueryInfo" in props:
        print("\nQueryInfo:")
        print_query_info(props["QueryInfo"])

def info_blob(props: dict):
    """Get some info blob (e.g. for tooltips); use HTML format."""

    info = "<big>Queries</big> (<i>unread</i>/<i>read</i>)\r\r"
    if "QueryInfo" in props:
        for item in props["QueryInfo"]:
            info += f'''<b>{item['name']}</b>: {item["unread"]}/{item["count"]}\r'''

    return info

def output_waybar(props: dict):
    """Output DBus information in Waybar format.

    The 'alt' field is one of 'new', 'unread' or 'empty', so it can be used to
    select an icon from Waybar's "format-icons" (which requires "{icon}" in the
    module's "format").
    """

    qinfo = props.get("QueryInfo") or []
    fav = next((item for item in qinfo if item.get("favorite")), None)

    if fav is None:
        print(json.dumps({"text": "", "alt": "empty", "tooltip":
                          info_blob(props)}))
        return

    # favorite, which is the query shown on the bar.
    if fav.get('delta-unread', 0) > 0:
        alt = "new"
        text = f"(<b>{fav['delta-unread']}</b>/{fav['unread']}/{fav['count']})"
    elif fav.get('unread', 0) > 0:
        alt = "unread"
        text = f"({fav['unread']}/{fav['count']})"
    else:
        alt = "empty"
        text = f"({fav['unread']}/{fav['count']})"

    output = {
        "text"    : text,
        "alt"     : alt,
        "class"   : alt,
        "tooltip" : info_blob(props)
    }
    print(f"{json.dumps(output)}")

Printer = Callable[[str], None]

async def do_output(output_func: Printer):
    """Grab the properties and output using output_func."""
    all_props = await get_all_properties()
    props = {k: unpack_variant(v) for k, v in all_props.items()}
    output_func(props)

# supported outputs
outputs = {
    "dump"   : output_dump,
    "waybar" : output_waybar
}

async def main():
    """Main routine"""

    # os.system
    parser = argparse.ArgumentParser(description="Mu4e D-Bus Client")
    parser.add_argument("-f", "--format", metavar='FORMAT', type=str,
                        default='dump', dest="format",
                        help='Output format')

    options = parser.parse_args()
    output_func = outputs.get(options.format)

    try:
        if output_func is None:
            raise ValueError(f"unknown format {options.format}")

        await do_output(output_func)

    except Exception as e:
        print(f"Error: could not connect to mu4e D-Bus service: {e}",
              file=sys.stderr)
        print("Make sure mu4e is running with mu4e-dbus-mode enabled.",
              file=sys.stderr)
        sys.exit(1)

if __name__ == "__main__":
    asyncio.run(main())