#!/usr/bin/env python

import base64
import json
import os
import pickle
import sys

from zammad_py import ZammadAPI
from zammad_py.api import Resource, TagList, TicketArticle

TEMPLATE = """{
"zammad_url": "",
"zammad_user": "",
"zammad_password": "",
"rt_url": "",
"rt_user": "",
"rt_pass": "",
"rt_start": 1,
"rt_end": 1000,
}
"""

COMMENT_TEMPLATE = """
Ticket imported from Request Tracker

URL: https://support.ungleich.ch/Ticket/Display.html?id={numerical_id}
Created: {Created}
Resolved: {Resolved}
"""

STATUSMAP = {"new": 1, "open": 2, "resolved": 4, "rejected": 4, "deleted": 4}
USERMAP = {}

ZAMMAD_SESSIONS = {}

### helpers ###

def get_zammad_session(impersonated_user=None):
    if impersonated_user in ZAMMAD_SESSIONS:
        return ZAMMAD_SESSIONS[impersonated_user]
    else:
        kwargs = {}
        if impersonated_user:
            kwargs["on_behalf_of"] = impersonated_user
        session = ZammadAPI(
            url=config["zammad_host"],
            username=config["zammad_user"],
            password=config["zammad_password"],
            **kwargs,
        )
        ZAMMAD_SESSIONS[impersonated_user or config["zammad_user"]] = session

        return session

def maybe_create_zammad_user(userdata, zammad_session, attr="login", default=None):
    # Map disabled users (in RT) to mock user in Zammad.
    if type(userdata) is str or "EmailAddress" not in userdata:
        userdata = {
            'EmailAddress': 'technik@ungleich.ch',
            'RealName': 'Disabled RT'
        }

    email = userdata["EmailAddress"]
    lowercase_email = email.lower()

    if lowercase_email not in USERMAP:
        kwargs = {"email": email}
        kwargs.update(config["userdata"])
        if "RealName" in userdata:
            realname = userdata["RealName"]
            if ", " in realname:
                last, first = realname.split(", ", 1)
            elif " " in realname:
                first, last = realname.split(None, 1)
            else:
                last = realname
                first = ""
            kwargs["lastname"] = last
            kwargs["firstname"] = first
        try:
            user = zammad_session.user.create(kwargs)
            USERMAP[lowercase_email] = user
        except:
            # The use probably exist already...
            result = list(zammad.user.search(lowercase_email))
            if len(result) == 1:
                user = list.pop(result)
                USERMAP[lowercase_email] = user
            else:
                print(f"Could not create/fetch user {lowercase_email}")

    if default is None:
        return USERMAP[lowercase_email][attr]

    return USERMAP[lowercase_email].get(attr, default)

### main logic ###

if not os.path.exists("rt2zammad.json"):
    print("Missing rt2zammad.json!")
    print("Create one based on following template:")
    print(TEMPLATE)
    sys.exit(1)

with open("rt2zammad.json") as handle:
    config = json.load(handle)

zammad = get_zammad_session()

os.makedirs("users", exist_ok=True)
os.makedirs("tickets", exist_ok=True)
os.makedirs("attachments", exist_ok=True)

ticket_ids = os.listdir("tickets/")
print(f"Found {len(ticket_ids)} tickets on filesystem.")

for id in ticket_ids:
    with open(f"tickets/{id}", "rb") as handle:
        rt_ticket = pickle.load(handle)

    label = "RT-{}".format(rt_ticket["ticket"]["original_id"])
    creator = rt_ticket["ticket"]["Creator"]
    with open(f"users/{creator}", "rb") as handle:
        rt_creator = pickle.load(handle)

    # The RT user object doesn't always contain everything (e.g. disabled users).
    if "EmailAddress" in rt_creator:
        creator = rt_creator["EmailAddress"]
    print(f"Importing {label} ({creator})")

    zammad_creator = maybe_create_zammad_user(rt_creator, zammad)

    # Make sure that we use what we created in Zammad, independently of what we
    # had in RT.
    creator = zammad_creator

    zammad_ticket_template = {
        "title": rt_ticket["ticket"]["Subject"],
        "group": "Users",
        "customer": creator,
        "note": "RT-import:{}".format(rt_ticket["ticket"]["original_id"]),
        "article": {
            "subject": rt_ticket["ticket"]["Subject"],
        },
    }

    # Ticket creation.
    merged = False
    if rt_ticket["ticket"]["original_id"] != rt_ticket["ticket"]["numerical_id"]:
        merged = True
        zammad_ticket_template["state_id"] = STATUSMAP["resolved"]
        zammad_ticket_template["article"]["body"] = "RT ticket merged into {}".format(
             rt_ticket["ticket"]["numerical_id"]
         )
        zammad_ticket = get_zammad_session(creator).ticket.create(zammad_ticket_template)
    else:
        zammad_ticket_template["state_id"] = STATUSMAP[rt_ticket["ticket"]["Status"]]
        body = rt_ticket["history"][0]["Content"] or 'RT Import: empty comment.'
        zammad_ticket_template["article"]["body"] = body
        zammad_ticket = get_zammad_session(creator).ticket.create(zammad_ticket_template)

    print(f"Created Zammad ticket {zammad_ticket['id']} for {label}")

    if rt_ticket["ticket"]["Owner"] and rt_ticket["ticket"]["Owner"] != "Nobody":
        zammad_owner_id = maybe_create_zammad_user(rt_ticket["ticket"]["Owner"], zammad, "id")
        zammad.ticket.update(
            zammad_ticket["id"], {"owner_id": zammad_owner_id}
        )

    # Ignore comments for merged tickets.
    if merged:
        continue

    # Internal note regarding the RT-Zammad import.
    TicketArticle(zammad).create(
        {
            "ticket_id": zammad_ticket["id"],
            "body": COMMENT_TEMPLATE.format(**rt_ticket["ticket"]),
            "internal": True,
        }
    )

    # Comments/notes within the ticket.
    for entry in rt_ticket["history"]:
        if entry["Type"] not in ("Correspond", "Comment"):
            continue

        # Attachments.
        files = []
        for a, title in entry["Attachments"]:
            with open(f"attachments/{id}/{a}", "rb") as handle:
                data = pickle.load(handle)

            if data["Filename"] in ("", "signature.asc"):
                continue
            files.append(
                {
                    "filename": data["Filename"],
                    "data": base64.b64encode(data["Content"]).decode("utf-8"),
                    "mime-type": data["ContentType"],
                }
            )

        # Comment/note.
        entry_creator = entry["Creator"]
        with open(f"users/{entry_creator}", "rb") as handle:
            rt_entry_creator = pickle.load(handle)

        zammad_creator = maybe_create_zammad_user(rt_entry_creator, zammad)
        zammad_entry_template = {
                "ticket_id": zammad_ticket["id"],
                "body": entry["Content"],
                "internal": entry["Type"] == "Comment",
                "attachments": files,
            }
        try:
            TicketArticle(get_zammad_session(zammad_creator)).create(zammad_entry_template)
        except:
            print(f"FIXME: Failed to add comment to ticket RT#{id}/Zammad#{zammad_ticket["id"]}: user permission issue?")