#!/usr/bin/env python3

from datetime import date, datetime, timedelta
import json
import os
import subprocess
import sys

import tanken
# Path where our data is stored persistent on disk
state_file = os.environ["GSB_STATE_FILE"]

if os.path.isfile(state_file):
    with open(state_file, "r") as state_f:
        state = json.load(state_f)
else:
    # Dict containing the whole state of geldschieberbot
    # balance - dict of dicts associating two persons to an amount
    # name2num, num2name - dicts associating numbers to names and vice versa
    # cars - dict associating car names to their service charge
    # scheduled_cmds - dict associating names to cmds, their schedule, and the last execution
    # changes - dict associating users with their changes
    state = {
        "balance": {},
        "name2num": {},
        "num2name": {},
        "cars": {},
        "scheduled_cmds": {},
        "changes": {},
    }

    # check if a legacy file layout is present
    store_dir = os.path.dirname(state_file)
    if os.path.isfile(os.path.join(store_dir, "balance.json")):
        with open(os.path.join(store_dir, "balance.json"), "r") as f:
            state["balance"] = json.load(f)

        with open(os.path.join(store_dir, "registration.json"), "r") as f:
            state["name2num"] = json.load(f)
        for _name in state["name2num"]:
            state["num2name"][state["name2num"][_name]] = _name

        with open(os.path.join(store_dir, "last_change.json"), "r") as f:
            state["changes"] = json.load(f)
        for _num in state["changes"]:
            _name = state["num2name"][_num]
            state["changes"][_name] = state["changes"][_num]
            del state["changes"][_num]

balance = state["balance"]
name2num = state["name2num"]
num2name = state["num2name"]
available_cars = state["cars"]
scheduled_cmds = state["scheduled_cmds"]
changes = state["changes"]

group_id = os.environ["GSB_GROUP_ID"]

send_cmd = os.environ["GSB_SEND_CMD"]
group_send_cmd = send_cmd + group_id

dry_run = False
"""Run without changing the stored state"""

quiet = False
"""Run without sending messages"""

record_changes = True
"""Should changes be recorded"""


def record(recipient, donor, amount):
    """Apply changes to the balance"""

    # Only change anything if this is not a dry run
    if dry_run:
        return

    balance[donor][recipient] += amount
    balance[recipient][donor] -= amount


def to_cent(euro):
    if '.' in euro:
        euro = euro.split('.')
    else:
        euro = euro.split(',')
    if len(euro) > 2:
        raise TypeError
    euro[0] = int(euro[0])
    if len(euro) < 2:
        euro.append(0)
    else:
        if len(euro[1]) == 1:
            euro[1] = int(euro[1]) * 10
        else:
            euro[1] = int(euro[1])
    amount = euro[0] * 100 + euro[1]
    if amount < 0:
        raise ValueError
    return amount


def to_euro(cents):
    return f"{cents/100:.2f}"


def send(msg):
    if not quiet:
        subprocess.run(send_cmd.split(' '), input=msg.encode(), check=False)


def create_summary(user):
    summary = ""
    cars_summary = ""
    total = 0
    cars_total = 0
    p_balances = balance[user]  # failes if user is not in balance
    for person in p_balances:
        amount = p_balances[person]
        if amount == 0:
            continue
        if person in available_cars:
            cars_total -= amount
            cars_summary += f'\t{"<-" if amount < 0 else "->"} {person} {to_euro(abs(amount))}\n'
        else:
            total -= amount
            summary += f'\t{"<-" if amount < 0 else "->"} {person} {to_euro(abs(amount))}\n'

    if not summary:
        summary = "\tAll fine :)"
    else:
        summary += f"\tBalance: {to_euro(total)}"

    ret_summary = f'{user}:\n{summary}'

    if cars_summary:
        cars_summary += f'\tLiability: {to_euro(cars_total)}'
        ret_summary += f'\n\tCars:\n{cars_summary}'

    return ret_summary


def create_total_summary():
    summary = "Summary:"

    cars_summary = ""
    for person in balance:
        p_summary = create_summary(person)
        if person in available_cars:
            cars_summary += f'\n{p_summary}'
        else:
            summary += f'\n{p_summary}'

    if cars_summary:
        summary += f'\nCars:{cars_summary}'
    return summary


def create_members():
    r = ""
    for m in name2num:
        r += m + ": " + name2num[m] + "\n"
    return r


def add_to_balance(name):
    nb = {}
    for m in balance:
        balance[m][name] = 0
        nb[m] = 0
    balance[name] = nb


def remove_from_balance(name):
    del balance[name]
    for m in balance:
        del balance[m][name]


def create_help():
    return """
Usage: send a message starting with '!' followed by a command
Commands:
ls | list - print all registered members
help - print this help message
reg name - register the sender with the name: name
sum [name] - print summary of specific users
full-sum - print summary of all users

split amount person [persons] - split amount between the sender and persons
teil amount person [persons] - split amount between the sender and persons

schieb amount recipient - give money to recipient
gib amount recipient - give money to recipient
zieh amount donor - get money from donor
nimm amount donor - get money from donor

transfer amount source destination - transfer amount of your balance from source to destination

cars [cmd] - interact with the available cars
cars [list | ls] - list available cars and their service charge
cars add car-name service-charge - add new car
cars new car-name service-charge - add new car
cars remove car-name - remove new car
cars pay car-name amount - pay a bill for the specified car

tanken amount [person] [car] [info] - calculate fuel costs, service charge and add them to the person's and car's balance respectively

fuck [change] - rewind last or specific change
list-changes [n] [first] - list the last n changes starting at first

weekly name cmd -  repeat cmd each week
monthly name cmd - repeat cmd each month
yearly name cmd - repeat cmd each year
cancel name - stop repeating cmd

Happy Geldschieben!
"""


cmds = {}


def register(sender, args, msg):
    if len(args) != 2:
        return None, f'not in form "{args[0]} name"'
    name = args[1]

    try:
        to_cent(name)
        return None, "pure numerical names are not allowed"
    except (ValueError, TypeError):
        pass

    if name in name2num:
        return None, f"{name} already registered"

    if sender in num2name:
        return None, "you are already registered"

    num2name[sender] = name
    name2num[name] = sender

    add_to_balance(name)

    # add changes list
    changes[name] = []
    return f"Happy geldschiebing {name}!", None


cmds["reg"] = register
cmds["register"] = register


def summary(sender, args, msg):  # pylint: disable=unused-argument
    if len(args) == 1:
        if not sender in num2name:
            return None, "You must register first to print your summary"
        name = num2name[sender]
        return f"Summary:\n{create_summary(name)}", None

    err = None
    msg = "Summary:\n"
    for name in args[1:]:
        if name in name2num or name in available_cars:
            msg += create_summary(name) + "\n"
        else:
            err = f'name "{name}" not registered'
    return msg, err


cmds["sum"] = summary
cmds["summary"] = summary


def full_summary(sender, args, msg):  # pylint: disable=unused-argument
    if len(args) == 1:
        return create_total_summary(), None
    else:
        return None, f"{args[0][1:]} takes no arguments"


cmds["full-sum"] = full_summary
cmds["full-summary"] = full_summary


def list_users(sender, args, msg):  # pylint: disable=unused-argument
    return create_members(), None


cmds["ls"] = list_users
cmds["list"] = list_users


def usage(sender, args, msg):  # pylint: disable=unused-argument
    return create_help(), None


cmds["help"] = usage
cmds["usage"] = usage


def split(sender, args, msg):
    if not sender in num2name:
        return None, 'you must register first'

    if len(args) < 3:
        return None, f'not in form "{args[0]} amount [name]+"'

    try:
        amount = to_cent(args[1])
        persons = args[2:]
    except (ValueError, TypeError):
        # support !split name amount
        if len(args) == 3:
            try:
                amount = to_cent(args[2])
                persons = [args[1]]
            except (ValueError, TypeError):
                return None, "amount must be a positive number"
        else:
            return None, "amount must be a positive number"

    # persons + sender
    npersons = len(persons) + 1
    amount_per_person = int(amount / npersons)

    if sender in num2name:
        recipient = num2name[sender]
    else:
        return None, "you must register first"

    output = f"Split {to_euro(amount)} between {npersons} -> {to_euro(amount_per_person)} each\n"
    change = [args]
    for p in persons:
        if p in name2num:
            if p == recipient:
                output += f"{p}, you will be charged multiple times. This may not be what you want\n"
            else:
                record(recipient, p, amount_per_person)
                change.append([recipient, p, amount_per_person])
        else:
            output += f"{p} not known. Please take care manually\n"

    if record_changes and not dry_run:
        changes[recipient].append(change)

    output += "New Balance:\n"
    output += create_summary(recipient)
    return output, None


cmds["split"] = split
cmds["teil"] = split


def transaction(sender, args, msg):
    if len(args) != 3:
        return None, f'not in form "{args[0]} amount recipient"'

    if not sender in balance:
        if sender not in num2name:
            return None, 'you must register first'
        sender = num2name[sender]

    if args[1] in balance:
        recipient, amount = args[1:3]
    elif args[2] in balance:
        amount, recipient = args[1:3]
    else:
        return None, 'recipient not known'

    if sender == recipient:
        return None, 'you can not transfer money to or from yourself'

    try:
        amount = to_cent(amount)
    except (ValueError, TypeError):
        return None, "amount must be a positive number"

    if args[0] in ["!zieh", "!nimm"]:
        amount *= -1

    if record_changes and not dry_run:
        changes[sender].append([args, [sender, recipient, amount]])

    record(sender, recipient, amount)

    p_balance = balance[sender][recipient]

    output = ("New Balance: {} {} {} {}\n".format(
        sender, ("->" if p_balance > 0 else "<-"), to_euro(abs(p_balance)),
        recipient))
    return output, None


cmds["schieb"] = transaction
cmds["gib"] = transaction
cmds["zieh"] = transaction
cmds["nimm"] = transaction


def transfer(sender, args, msg):
    if len(args) < 4:
        return None, f'not in form "{args[0]} amount source destination"'

    if not sender in num2name:
        return None, 'you must register first'

    sender = num2name[sender]

    try:
        amount_raw = args[1]
        amount_cent = to_cent(amount_raw)
    except (ValueError, TypeError):
        return None, "amount must be a positive number"

    source, destination = args[2:4]
    if source not in balance:
        return None, f'source "{source}" not known'

    if destination not in balance:
        return None, f'destination "{destination}" not known'

    output = ""
    global record_changes
    saved_record_changes = record_changes
    record_changes = False
    change = [args]

    ret, err = transaction(sender, ["!zieh", source, amount_raw], "")
    if err:
        # No changes yet we can fail
        return None, err

    output += ret
    # Sender <- X Source
    change.append((sender, source, -amount_cent))

    ret, err = transaction(sender, ["!schieb", destination, amount_raw], "")
    if err:
        output += err + "\nThe balance may be in a inconsistent state please take care manually"
        return output, None

    output += ret
    # Sender -> X Destination
    change.append((sender, destination, amount_cent))

    ret, err = transaction(source, ["!zieh", destination, amount_raw], "")
    if err:
        output += err + "\nThe balance may be in a inconsistent state please take care manually"
        return output, None

    output += ret
    # Destination -> X Source
    change.append((destination, source, amount_cent))

    record_changes = saved_record_changes
    if err is None and record_changes and not dry_run:
        changes[sender].append(change)

    return output, None


cmds["transfer"] = transfer


def cars(sender, args, msg):
    # list cars
    if len(args) < 2 or args[1] in ["ls", "list"]:
        if len(available_cars) == 0:
            return "No cars registered yet.", None

        ret_msg = ""

        if len(args) > 2:
            cars_to_list = args[2:]
        else:
            cars_to_list = available_cars

        for car in cars_to_list:
            if car in available_cars:
                ret_msg += f"{car} - service charge {available_cars[car]}ct/km\n"
                ret_msg += create_summary(car) + "\n"
            else:
                return None, f'"{car}" is no available car\n'

        return ret_msg[:-1], None

    # add car
    if args[1] in ["add", "new"]:
        if len(args) < 4:
            return None, f'not in form "{args[0]} {args[1]} car-name service-charge"'

        car = args[2]
        if car in available_cars:
            return None, f'"{car}" already registered'

        if car in balance:
            return None, f'A user named "{car}" already exists. Please use a different name for this car'

        try:
            service_charge = to_cent(args[3])
        except (ValueError, TypeError):
            return None, "service-charge must be a positive number"

        available_cars[car] = service_charge
        add_to_balance(car)
        return f'added "{car}" as an available car', None

    # remove car
    if args[1] in ["rm", "remove"]:
        if len(args) < 3:
            return None, f'not in form "{args[0]} {args[1]} car-name"'

        car = args[2]
        if car not in available_cars:
            return None, f'A car with the name "{car}" does not exists'

        del available_cars[car]
        remove_from_balance(car)
        return f'removed "{car}" from the available cars', None

    # pay bill
    if args[1] in ["pay"]:
        if len(args) < 4:
            return None, f'not in form "{args[0]} {args[1]} car-name amount"'

        if not sender in num2name:
            return None, "you must register first"

        sender_name = num2name[sender]

        car = args[2]
        if car not in available_cars:
            return None, f'car "{car}" not known'

        try:
            amount = to_cent(args[3])
            amount_euro = to_euro(amount)
        except (ValueError, TypeError):
            return None, "amount must be a positive number"

        output = ""

        global record_changes
        saved_record_changes = record_changes
        record_changes = False
        change = [args]

        total_available_charge = 0
        available_charges = []
        for person in balance[car]:
            _amount = balance[car][person]
            if _amount < 0:
                total_available_charge -= _amount
                available_charges.append((person, _amount))

        proportion = -1
        if amount < total_available_charge:
            proportion = -1 * (amount / total_available_charge)

        _, err = transaction(sender, f"!gib {car} {amount_euro}".split(), "")
        assert err is None
        output += f"{sender_name} payed {amount_euro}\n"

        # transfer money
        output += f"Transferring {proportion * -100:.2f}% of everybody's charges\n"
        for person, _amount in available_charges:
            if person == sender_name or _amount >= 0:
                continue

            to_move = int(_amount * proportion)
            to_move_euro = to_euro(to_move)
            ret, err = transfer(sender,
                                ["transfer", to_move_euro, car, person], "")
            assert err is None

            output += "Transfer {} from {} to {}\n".format(
                to_move_euro, person, sender_name)

        output += "New Balances:\n"
        output += create_summary(sender_name) + "\n"
        output += create_summary(car)

        record_changes = saved_record_changes
        if record_changes and not dry_run:
            changes[sender_name].append(change)

        return output, None

    return None, f'unknown car subcommand "{args[1]}".'


cmds["cars"] = cars


def _tanken(sender, args, msg):
    if len(args) < 2:
        return None, f'not in form "{args[0]} amount [person] [car] [info]"'
    try:
        amount = to_cent(args[1])
    except (ValueError, TypeError):
        return None, "amount must be a number"

    # find recipient
    if len(args) > 2 and args[2] in name2num:
        recipient = args[2]
    elif sender in num2name:
        recipient = num2name[sender]
    else:
        return None, "recipient unknown"

    # find car
    car = None
    if len(args) > 2 and args[2] in available_cars:
        car = args[2]
    elif len(args) > 3 and args[3] in available_cars:
        car = args[3]

    service_charge = 0
    if car:
        service_charge = available_cars[car]

    parts, err = tanken.tanken(msg[1:], amount, service_charge)

    if err:
        return None, err

    output = ""
    change = [args]
    for pname, values in parts.items():
        output += pname + ": {}km = fuel: {}, service charge: {}\n".format(
            values["distance"], to_euro(values["cost"]),
            to_euro(values["service_charge"]))
        # record service charges
        if pname not in name2num:
            output += pname + " not known."
        if car:
            person_to_charge = pname
            if pname not in name2num:
                person_to_charge = recipient
                output += f" {recipient} held accountable for service charge."

            record(car, person_to_charge, values["service_charge"])
            change.append([car, person_to_charge, values["service_charge"]])

        # recipient paid the fuel -> don't charge them
        if pname == recipient:
            continue

        if pname in name2num:
            record(recipient, pname, values["cost"])
            change.append([recipient, pname, values["cost"]])
        else:
            output += " Please collect fuel cost manually\n"

    if record_changes and not dry_run:
        changes[num2name[sender]].append(change)

    output += "New Balance:\n"
    output += create_summary(recipient)
    if car:
        output += "\nCar "
        output += create_summary(car)
    return output, None


cmds["tanken"] = _tanken


def fuck(sender, args, msg):
    if not sender in num2name:
        return None, "you must register first"

    name = num2name[sender]

    nchanges = len(changes[name])
    if nchanges == 0:
        return "Nothing to rewind", None

    change_to_rewind = -1
    if len(args) >= 2:
        try:
            change_to_rewind = int(args[1]) - 1
        except ValueError:
            return None, "change to rewind must be a number"

        if change_to_rewind > nchanges:
            return None, "change to rewind is bigger than there are changes"

    # pop last item
    last_changes = changes[name].pop(change_to_rewind)
    args, last_changes = last_changes[0], last_changes[1:]

    output = name + ": sorry I fucked up!\nRewinding:\n"
    output += ' '.join(args) + "\n"
    for change in last_changes:
        if not change[0] in cmds:
            output += "{} {} {} {}\n".format(change[0],
                                             ("->" if change[2] < 0 else "<-"),
                                             to_euro(abs(change[2])),
                                             change[1])
            record(change[1], change[0], change[2])

    for change in last_changes:
        if change[0] in cmds:
            ret, err = cmds[change[0]](sender, change, "")

            if err:
                output += "ERROR: " + err
            else:
                output += ret

    return output, None


cmds["fuck"] = fuck
cmds["rewind"] = fuck
cmds["undo"] = fuck


def list_changes(sender, args, msg):
    if not sender in num2name:
        return None, "you must register first"

    sender_name = num2name[sender]

    changes_to_list = 5
    if len(args) >= 2:
        try:
            changes_to_list = int(args[1])
        except ValueError:
            return None, 'the amount of changes to list must be a number'

    nchanges = len(changes[sender_name])
    if nchanges == 0:
        return "Nothing to list", None

    first_to_list = max(nchanges - changes_to_list, 0)

    if len(args) == 3:
        try:
            first_to_list = int(args[2]) - 1
        except ValueError:
            return None, 'the first change to list must be a number'

        if first_to_list > nchanges:
            return None, 'the first change to list is bigger than there are changes'

    msg = ""
    for i, change in enumerate(changes[sender_name]):
        if i < first_to_list:
            continue

        if i >= first_to_list + changes_to_list:
            # i is used to track how many changes we listed
            # This change will not be listed so decrement i before extiting the loop.
            i -= 1
            break

        msg += f'Change {i + 1}:\n'
        msg += f'\t{" ".join(change[0])}\n'
        for sender, recipient, amount in change[1:]:
            msg += "\t{} {} {} {}\n".format(sender,
                                            ("->" if amount < 0 else "<-"),
                                            to_euro(abs(amount)), recipient)

    # prepend message header because we want to know how much changes we actually listed
    msg = f'Changes from {sender_name} {first_to_list + 1}-{i + 1}\n' + msg

    return msg, None


cmds["list-changes"] = list_changes


def schedule(sender, args, msg):
    if not sender in num2name:
        return None, "you must register first"

    sender_name = num2name[sender]

    if len(args) < 3:
        return None, f'not in form "{args[0]} name cmd"'

    name = args[1]
    cmd = args[2:]

    if name in scheduled_cmds:
        return None, f'there is already a scheduled command named "{name}"'

    # Test the command
    global dry_run
    old_dry_run, dry_run = dry_run, True

    ret, err = cmds[cmd[0]](sender, cmd, "")

    dry_run = old_dry_run

    if err:
        return None, 'the command "{}" failed and will not be recorded'

    scheduled_cmd = {
        "schedule": args[0][1:],
        "last_time": None,
        "sender": sender,
        "cmd": cmd
    }

    scheduled_cmds[name] = scheduled_cmd
    output = 'Recorded the {} command "{}" as "{}"\n'.format(
        args[0][1:], ' '.join(cmd), name)

    output += "Running {} command {} for {} initially\n".format(
        scheduled_cmd["schedule"], name, sender_name)

    ret, err = cmds[cmd[0]](sender, cmd, "")
    if err:
        output += "ERROR: " + err
    else:
        output += ret

    changes[sender_name][0].append(["cancel", name])

    now = datetime.now().date()
    scheduled_cmd["last_time"] = now.isoformat()

    return output, None


cmds["weekly"] = schedule
cmds["monthly"] = schedule
cmds["yearly"] = schedule


def cancel(sender, args, msg):
    cmd_name = args[1]
    if not cmd_name in scheduled_cmds:
        return None, f'"{cmd_name}" is not a scheduled command'
    cmd = scheduled_cmds[cmd_name]

    if not cmd["sender"] == sender:
        return None, 'only the original creator can cancel this command'

    del scheduled_cmds[cmd_name]
    return f'Cancelled the {cmd["schedule"]} cmd "{cmd_name}"', None


cmds["cancel"] = cancel


def thanks(sender, args, msg):
    sender_name = num2name.get(sender, sender)
    msg = f'You are welcome. It is a pleasure to work with you, {sender_name}.'
    nick = None if len(args) == 1 else args[1]
    if nick:
        msg = f"{msg}\nBut don't call me {nick}."

    return msg, None


cmds["thanks"] = thanks


def main():
    if len(sys.argv) > 1 and sys.argv[1] in ["-d", "--dry-run"]:
        global dry_run
        dry_run = True
        print("Dry Run no changes will apply!")

    # Read cmds from stdin
    for l in sys.stdin.read().splitlines():
        try:
            message = json.loads(l)["envelope"]
        except:
            print(datetime.now(), l, "not valid json")
            continue

        sender_number = message["source"]
        if not "dataMessage" in message or not message[
                "dataMessage"] or not message["dataMessage"]["message"]:
            continue
        else:
            message = message["dataMessage"]
            if message["groupInfo"] and message["groupInfo"][
                    "groupId"] != group_id:
                continue
            body = [l.strip() for l in message["message"].lower().splitlines()]

            if len(body) == 0:
                continue

        args = body[0].split(' ')

        if args[0].startswith("!"):
            cmd = args[0][1:]
            if cmd in cmds:
                ret, err = cmds[cmd](sender_number, args, body)
                if err:
                    send("ERROR: " + err)
                else:
                    send(ret)
            else:
                send('ERROR: unknown cmd. Enter !help for a list of commands.')

        # Handle scheduled commands
        global record_changes
        record_changes = False

        now = datetime.now().date()
        week_delta = timedelta(days=7)
        for name, cmd in scheduled_cmds.items():

            last_time = cmd["last_time"]
            if hasattr(date, "fromisoformat"):
                last_time = date.fromisoformat(last_time)
            else:
                last_time = date(*map(int, last_time.split("-")))

            d = last_time
            while True:
                if cmd["schedule"] == "yearly":
                    d = date(d.year + 1, d.month, d.day)
                elif cmd["schedule"] == "monthly":
                    if d.day > 28:
                        d = date(d.year, d.month, 28)
                    if d.month == 12:
                        d = date(d.year + 1, 1, d.day)
                    else:
                        d = date(d.year, d.month + 1, d.day)
                else:
                    d = d + week_delta

                if d <= now:
                    send("Running {} command {} for {} triggered on {}\n".
                         format(cmd["schedule"], name, num2name[cmd["sender"]],
                                d.isoformat()))

                    ret, err = cmds[cmd["cmd"][0]](cmd["sender"], cmd["cmd"],
                                                   "")

                    if err:
                        send("ERROR: " + err)
                    else:
                        send(ret)

                    cmd["last_time"] = d.isoformat()
                else:
                    break

        with open(state_file, "w") as f:
            json.dump(state, f)


if __name__ == "__main__":
    main()