import celery
import curses
import sys
import threading
import time

from datetime import datetime
from itertools import count
from textwrap import wrap
from math import ceil

from celery import states
from celery.app import app_or_default
from celery.utils import abbr, abbrtask

BORDER_SPACING = 4
LEFT_BORDER_OFFSET = 3
UUID_WIDTH = 36
STATE_WIDTH = 8
TIMESTAMP_WIDTH = 8
MIN_WORKER_WIDTH = 15
MIN_TASK_WIDTH = 16


class CursesMonitor(object):
    keymap = {}
    win = None
    screen_width = None
    screen_delay = 10
    selected_task = None
    selected_position = 0
    selected_str = "Selected: "
    foreground = curses.COLOR_BLACK
    background = curses.COLOR_WHITE
    online_str = "Workers online: "
    help_title = "Keys: "
    help = ("j:up k:down i:info t:traceback r:result c:revoke ^c: quit")
    greet = "celeryev %s" % celery.__version__
    info_str = "Info: "

    def __init__(self, state, keymap=None, app=None):
        self.app = app_or_default(app)
        self.keymap = keymap or self.keymap
        self.state = state
        default_keymap = {"J": self.move_selection_down,
                          "K": self.move_selection_up,
                          "C": self.revoke_selection,
                          "T": self.selection_traceback,
                          "R": self.selection_result,
                          "I": self.selection_info,
                          "L": self.selection_rate_limit}
        self.keymap = dict(default_keymap, **self.keymap)

    def format_row(self, uuid, task, worker, timestamp, state):
        mx = self.display_width

        # include spacing
        detail_width = mx - 1 - STATE_WIDTH - 1 - TIMESTAMP_WIDTH
        uuid_space = detail_width - 1 - MIN_TASK_WIDTH - 1 - MIN_WORKER_WIDTH

        if uuid_space < UUID_WIDTH:
            uuid_width = uuid_space
        else:
            uuid_width = UUID_WIDTH

        detail_width = detail_width - uuid_width - 1
        task_width = int(ceil(detail_width / 2.0))
        worker_width = detail_width - task_width - 1

        uuid = abbr(uuid, uuid_width).ljust(uuid_width)
        worker = abbr(worker, worker_width).ljust(worker_width)
        task = abbrtask(task, task_width).ljust(task_width)
        state = abbr(state, STATE_WIDTH).ljust(STATE_WIDTH)
        timestamp = timestamp.ljust(TIMESTAMP_WIDTH)

        row = "%s %s %s %s %s " % (uuid, worker, task, timestamp, state)
        if self.screen_width is None:
            self.screen_width = len(row[:mx])
        return row[:mx]

    @property
    def screen_width(self):
        _, mx = self.win.getmaxyx()
        return mx

    @property
    def screen_height(self):
        my, _ = self.win.getmaxyx()
        return my

    @property
    def display_width(self):
        _, mx = self.win.getmaxyx()
        return mx - BORDER_SPACING

    @property
    def display_height(self):
        my, _ = self.win.getmaxyx()
        return my - 10

    @property
    def limit(self):
        return self.display_height

    def find_position(self):
        if not self.tasks:
            return 0
        for i, e in enumerate(self.tasks):
            if self.selected_task == e[0]:
                return i
        return 0

    def move_selection_up(self):
        self.move_selection(-1)

    def move_selection_down(self):
        self.move_selection(1)

    def move_selection(self, direction=1):
        if not self.tasks:
            return
        pos = self.find_position()
        try:
            self.selected_task = self.tasks[pos + direction][0]
        except IndexError:
            self.selected_task = self.tasks[0][0]

    keyalias = {curses.KEY_DOWN: "J",
                curses.KEY_UP: "K",
                curses.KEY_ENTER: "I"}

    def handle_keypress(self):
        try:
            key = self.win.getkey().upper()
        except:
            return
        key = self.keyalias.get(key) or key
        handler = self.keymap.get(key)
        if handler is not None:
            handler()

    def alert(self, callback, title=None):
        self.win.erase()
        my, mx = self.win.getmaxyx()
        y = blank_line = count(2).next
        if title:
            self.win.addstr(y(), 3, title, curses.A_BOLD | curses.A_UNDERLINE)
            blank_line()
        callback(my, mx, y())
        self.win.addstr(my - 1, 0, "Press any key to continue...",
                        curses.A_BOLD)
        self.win.refresh()
        while 1:
            try:
                return self.win.getkey().upper()
            except:
                pass

    def selection_rate_limit(self):
        if not self.selected_task:
            return curses.beep()
        task = self.state.tasks[self.selected_task]
        if not task.name:
            return curses.beep()

        my, mx = self.win.getmaxyx()
        r = "New rate limit: "
        self.win.addstr(my - 2, 3, r, curses.A_BOLD | curses.A_UNDERLINE)
        self.win.addstr(my - 2, len(r) + 3, " " * (mx - len(r)))
        rlimit = self.readline(my - 2, 3 + len(r))

        if rlimit:
            reply = self.app.control.rate_limit(task.name,
                                                rlimit.strip(), reply=True)
            self.alert_remote_control_reply(reply)

    def alert_remote_control_reply(self, reply):

        def callback(my, mx, xs):
            y = count(xs).next
            if not reply:
                self.win.addstr(y(), 3, "No replies received in 1s deadline.",
                        curses.A_BOLD + curses.color_pair(2))
                return

            for subreply in reply:
                curline = y()

                host, response = subreply.items()[0]
                host = "%s: " % host
                self.win.addstr(curline, 3, host, curses.A_BOLD)
                attr = curses.A_NORMAL
                text = ""
                if "error" in response:
                    text = response["error"]
                    attr |= curses.color_pair(2)
                elif "ok" in response:
                    text = response["ok"]
                    attr |= curses.color_pair(3)
                self.win.addstr(curline, 3 + len(host), text, attr)

        return self.alert(callback, "Remote Control Command Replies")

    def readline(self, x, y):
        buffer = str()
        curses.echo()
        try:
            i = 0
            while True:
                ch = self.win.getch(x, y + i)
                if ch != -1:
                    if ch in (10, curses.KEY_ENTER):            # enter
                        break
                    if ch in (27, ):
                        buffer = str()
                        break
                    buffer += chr(ch)
                    i += 1
        finally:
            curses.noecho()
        return buffer

    def revoke_selection(self):
        if not self.selected_task:
            return curses.beep()
        reply = self.app.control.revoke(self.selected_task, reply=True)
        self.alert_remote_control_reply(reply)

    def selection_info(self):
        if not self.selected_task:
            return

        def alert_callback(mx, my, xs):
            my, mx = self.win.getmaxyx()
            y = count(xs).next
            task = self.state.tasks[self.selected_task]
            info = task.info(extra=["state"])
            infoitems = [("args", info.pop("args", None)),
                         ("kwargs", info.pop("kwargs", None))] + info.items()
            for key, value in infoitems:
                if key is None:
                    continue
                value = str(value)
                curline = y()
                keys = key + ": "
                self.win.addstr(curline, 3, keys, curses.A_BOLD)
                wrapped = wrap(value, mx - 2)
                if len(wrapped) == 1:
                    self.win.addstr(curline, len(keys) + 3,
                            abbr(wrapped[0],
                                 self.screen_width - (len(keys) + 3)))
                else:
                    for subline in wrapped:
                        nexty = y()
                        if nexty >= my - 1:
                            subline = " " * 4 + "[...]"
                        elif nexty >= my:
                            break
                        self.win.addstr(nexty, 3,
                                abbr(" " * 4 + subline, self.screen_width - 4),
                                curses.A_NORMAL)

        return self.alert(alert_callback,
                "Task details for %s" % self.selected_task)

    def selection_traceback(self):
        if not self.selected_task:
            return curses.beep()
        task = self.state.tasks[self.selected_task]
        if task.state not in states.EXCEPTION_STATES:
            return curses.beep()

        def alert_callback(my, mx, xs):
            y = count(xs).next
            for line in task.traceback.split("\n"):
                self.win.addstr(y(), 3, line)

        return self.alert(alert_callback,
                "Task Exception Traceback for %s" % self.selected_task)

    def selection_result(self):
        if not self.selected_task:
            return

        def alert_callback(my, mx, xs):
            y = count(xs).next
            task = self.state.tasks[self.selected_task]
            result = getattr(task, "result", None) or getattr(task,
                    "exception", None)
            for line in wrap(result, mx - 2):
                self.win.addstr(y(), 3, line)

        return self.alert(alert_callback,
                "Task Result for %s" % self.selected_task)

    def display_task_row(self, lineno, task):
        state_color = self.state_colors.get(task.state)
        attr = curses.A_NORMAL
        if task.uuid == self.selected_task:
            attr = curses.A_STANDOUT
        timestamp = datetime.fromtimestamp(
                        task.timestamp or time.time())
        timef = timestamp.strftime("%H:%M:%S")
        line = self.format_row(task.uuid, task.name,
                               task.worker.hostname,
                               timef, task.state)
        self.win.addstr(lineno, LEFT_BORDER_OFFSET, line, attr)

        if state_color:
            self.win.addstr(lineno,
                            len(line) - STATE_WIDTH + BORDER_SPACING - 1,
                            task.state, state_color | attr)

    def draw(self):
        win = self.win
        self.handle_keypress()
        x = LEFT_BORDER_OFFSET
        y = blank_line = count(2).next
        my, mx = win.getmaxyx()
        win.erase()
        win.bkgd(" ", curses.color_pair(1))
        win.border()
        win.addstr(1, x, self.greet, curses.A_DIM | curses.color_pair(5))
        blank_line()
        win.addstr(y(), x, self.format_row("UUID", "TASK",
                                           "WORKER", "TIME", "STATE"),
                curses.A_BOLD | curses.A_UNDERLINE)
        tasks = self.tasks
        if tasks:
            for row, (uuid, task) in enumerate(tasks):
                if row > self.display_height:
                    break

                if task.uuid:
                    lineno = y()
                self.display_task_row(lineno, task)

        # -- Footer
        blank_line()
        win.hline(my - 6, x, curses.ACS_HLINE, self.screen_width - 4)

        # Selected Task Info
        if self.selected_task:
            win.addstr(my - 5, x, self.selected_str, curses.A_BOLD)
            info = "Missing extended info"
            detail = ""
            try:
                selection = self.state.tasks[self.selected_task]
            except KeyError:
                pass
            else:
                info = selection.info(["args", "kwargs",
                                       "result", "runtime", "eta"])
                if "runtime" in info:
                    info["runtime"] = "%.2fs" % info["runtime"]
                if "result" in info:
                    info["result"] = abbr(info["result"], 16)
                info = " ".join("%s=%s" % (key, value)
                            for key, value in info.items())
                detail = "... -> key i"
            infowin = abbr(info,
                           self.screen_width - len(self.selected_str) - 2,
                           detail)
            win.addstr(my - 5, x + len(self.selected_str), infowin)
            # Make ellipsis bold
            if detail in infowin:
                detailpos = len(infowin) - len(detail)
                win.addstr(my - 5, x + len(self.selected_str) + detailpos,
                        detail, curses.A_BOLD)
        else:
            win.addstr(my - 5, x, "No task selected", curses.A_NORMAL)

        # Workers
        if self.workers:
            win.addstr(my - 4, x, self.online_str, curses.A_BOLD)
            win.addstr(my - 4, x + len(self.online_str),
                    ", ".join(sorted(self.workers)), curses.A_NORMAL)
        else:
            win.addstr(my - 4, x, "No workers discovered.")

        # Info
        win.addstr(my - 3, x, self.info_str, curses.A_BOLD)
        win.addstr(my - 3, x + len(self.info_str),
                "events:%s tasks:%s workers:%s/%s" % (
                    self.state.event_count, self.state.task_count,
                    len([w for w in self.state.workers.values()
                            if w.alive]),
                    len(self.state.workers)),
                curses.A_DIM)

        # Help
        self.safe_add_str(my - 2, x, self.help_title, curses.A_BOLD)
        self.safe_add_str(my - 2, x + len(self.help_title), self.help,
                          curses.A_DIM)
        win.refresh()

    def safe_add_str(self, y, x, string, *args, **kwargs):
        if x + len(string) > self.screen_width:
            string = string[:self.screen_width - x]
        self.win.addstr(y, x, string, *args, **kwargs)

    def init_screen(self):
        self.win = curses.initscr()
        self.win.nodelay(True)
        self.win.keypad(True)
        curses.start_color()
        curses.init_pair(1, self.foreground, self.background)
        # exception states
        curses.init_pair(2, curses.COLOR_RED, self.background)
        # successful state
        curses.init_pair(3, curses.COLOR_GREEN, self.background)
        # revoked state
        curses.init_pair(4, curses.COLOR_MAGENTA, self.background)
        # greeting
        curses.init_pair(5, curses.COLOR_BLUE, self.background)
        # started state
        curses.init_pair(6, curses.COLOR_YELLOW, self.foreground)

        self.state_colors = {states.SUCCESS: curses.color_pair(3),
                             states.REVOKED: curses.color_pair(4),
                             states.STARTED: curses.color_pair(6)}
        for state in states.EXCEPTION_STATES:
            self.state_colors[state] = curses.color_pair(2)

        curses.cbreak()

    def resetscreen(self):
        curses.nocbreak()
        self.win.keypad(False)
        curses.echo()
        curses.endwin()

    def nap(self):
        curses.napms(self.screen_delay)

    @property
    def tasks(self):
        return self.state.tasks_by_timestamp()[:self.limit]

    @property
    def workers(self):
        return [hostname
                    for hostname, w in self.state.workers.items()
                        if w.alive]


class DisplayThread(threading.Thread):

    def __init__(self, display):
        self.display = display
        self.shutdown = False
        threading.Thread.__init__(self)

    def run(self):
        while not self.shutdown:
            self.display.draw()
            self.display.nap()


def evtop(app=None):
    sys.stderr.write("-> evtop: starting capture...\n")
    app = app_or_default(app)
    state = app.events.State()
    conn = app.broker_connection()
    recv = app.events.Receiver(conn, handlers={"*": state.event})
    capture = recv.itercapture()
    capture.next()
    display = CursesMonitor(state, app=app)
    display.init_screen()
    refresher = DisplayThread(display)
    refresher.start()
    try:
        capture.next()
    except Exception:
        refresher.shutdown = True
        refresher.join()
        display.resetscreen()
        raise
    except (KeyboardInterrupt, SystemExit):
        conn and conn.close()
        refresher.shutdown = True
        refresher.join()
        display.resetscreen()


if __name__ == "__main__":
    evtop()