import curses
import os
import datetime as dt
import threading
import traceback as tb

import blc2 

from blc2.functions.audio import Audio
from blc2.functions.scene import Scene
from blc2.functions.chaser import Chaser
from blc2.functions.chaserstep import ChaserStep
from blc2.functions.join import Join
from blc2.constants import SCENE, CHASER, AUDIO, MANUAL, INHERIT, INFTY, CHASERSTEP, JOIN, ONESHOT, LOOP

from blc2.topology import Fixture

from blc2.workspace import Workspace

from .globals import CURSES_LOCK 
from .input.tabcomp import Input 
from .channelbank import ChannelBank
from .chaserview import ChaserView
from .pager import Pager
from .dialog import askyesnocancel
from .audioview import AudioView
from .render import Renderer
from .dummy import DummyOutput

def wrap_curses(f):
    def inner(*args, **kwargs):
        return curses.wrapper(lambda stdscr: f(*args, stdscr, **kwargs))
    return inner

__version__ = "v0.0.3"

class Interface:
    def _compute_sizes(self, height, width):
        hb = height // 2
        ht = height - hb

        wr = width // 2
        wl = width - wr - 1

        chasers = []
        if self.chaser_views:
            current = 0
            cw = (wl // len(self.chaser_views)) - 1
            for i in range(len(self.chaser_views)):
                curw = (wl - current) if (i+1) == len(self.chaser_views) else cw
                chasers.append(((hb, curw), (ht, current)))
                current += curw + 1

        return (
            ((ht, width), (0, 0),),
            ((4, wr), (height-4, wl+1),), 
            ((hb - 4, wr), (ht, wl+1),),
            *chasers
        )

    def _resize(self):
        ## FIXME
        self._actual_resize()
        self._actual_resize()

    def _actual_resize(self):
        for (a1, a2), (f1, f2) in zip(self._compute_sizes(*self.stdscr.getmaxyx()), ((self.channel_bank.set_dim, self.channel_bank.set_pos), (self.input.set_dim, self.input.set_pos), (self.pager.set_dim, self.pager.set_pos), *((c.set_dim, c.set_pos) for c in self.chaser_views))):
            f1(*a1)
            f2(*a2)

    @wrap_curses
    def main(self, stdscr):
        height, width = stdscr.getmaxyx()
        self.stdscr = stdscr
        (cbd, cbp), (ind, inp), (pgd, pgp) = self._compute_sizes(height, width)
        self.channel_bank = ChannelBank(*cbp, *cbd)
        self.input = Input(*inp, *ind)
        self.input.context = self.context_base
        self.pager = Pager(*pgp, *pgd)

        todisp = [
            "Welcome to BLC2!",
            "Currently running library %s, interface %s" % (blc2.__version__, __version__),
            "",
        ]

        if self._w_created:
            todisp.append("Created a new workspace")
        else:
            todisp.append("Loaded workspace \"%s\" from \"%s\"" % (self.w.name, self.path))
            todisp.append("Authored by %s, last modified at %s" % (self.w.author, self.w.modified.strftime("%Y-%m-%d %H:%M:%S")))

        self.pager.display_many(todisp)

        if not self.output.ok:
            self.pager.display_many(("WARNING: Output is not OK!",), True)

        self.input.main(self._resize)

    def handle_show(self, f):
        with self.w_lock:
            if f is None or f.type == SCENE:
                if not isinstance(self.channel_bank, ChannelBank):
                    (hw, yx), *_ = self._compute_sizes(*self.stdscr.getmaxyx())
                    self.channel_bank = ChannelBank(*yx, *hw)
                if f is None:
                    return
                self.channel_bank.set_scope(f.scope)
                self.channel_bank.set_values(f.values.items())
            elif f.type == AUDIO:
                if not isinstance(self.channel_bank, AudioView):
                    (hw, yx), *_ = self._compute_sizes(*self.stdscr.getmaxyx())
                    self.channel_bank = AudioView(*yx, *hw)
                self.channel_bank.audio = f
            self.channel_bank.title = f.type + ' "%s"' % f.name
            self.renderer.clear_hold()
            if f.type == SCENE:
                self.renderer.hold(f.values)

    def handle_enter(self, fid):
        with self.w_lock:
            if fid is None:
                if not self.chaser_views:
                    return "No chaser loaded"
                f = self.chaser_views[0].chaser
            else:
                if fid not in self.w.functions:
                    return "No such function"
                f = self.w.functions[fid]

            if self.current_cv is not None:
                self.current_cv.highlight = False

            if self.chaser is not None:
                cv = [c for c in self.chaser_views if c.chaser == self.chaser][0].selected
                self.chaser_stack.append((self.chaser, cv))
                self.chaser = None

            if f.type == SCENE:
                self.primitive = f
                self.handle_show(f)
                self.channel_bank.highlight = True
                self.input.context = self.context_scene
            elif f.type in (CHASER, JOIN):
                self.chaser = f
                cv = [c for c in self.chaser_views if c.chaser == f]
                if not cv:
                    if len(self.chaser_views) == 2:
                        self.chaser_views[1].set_chaser(f, None)
                    else:
                        self.base_add(f.id)
                    self.current_cv = self.chaser_views[-1]
                else:
                    cv = cv[0]
                    self.current_cv = cv
                self.current_cv.highlight = True
                if f.type == CHASER:
                    self.input.context = self.context_chaser
                elif f.type == JOIN:
                    self.input.context = self.context_join
            elif f.type == AUDIO:
                self.primitive = f
                self.handle_show(f)
                self.channel_bank.highlight = True
                self.input.context = self.context_audio
            else:
                ## FIXME
                return "No other types allowed yet"

    def base_add(self, fid):
        with self.w_lock:
            if fid not in self.w.functions:
                return "No such function"
            f = self.w.functions[fid]
            if f.type not in (CHASER, JOIN):
                return "Can only add chasers!"
            with CURSES_LOCK:
                if True in (c.chaser.id for c in self.chaser_views):
                    return "Already added!"
                elif len(self.chaser_views) == 2:
                    ## FIXME?
                    return "Can only use two for now"
                self.chaser_views.append(None)
                ld, lp = self._compute_sizes(*self.stdscr.getmaxyx())[-1]
                self.chaser_views[-1] = ChaserView(*lp, *ld)
                self._resize()
                self.chaser_views[-1].set_chaser(f, None)

    def base_remove(self, n, index=True):
        with self.w_lock:
            if not index:
                n = [j for j, i in enumerate(self.chaser_views) if i.chaser.id == n]
                if not n:
                    return "No such chaser loaded"
                n = n[0]
            if n >= len(self.chaser_views) or n < 0:
                return "Index out of range"
            with CURSES_LOCK:
                self.chaser_views[n].win.erase()
                self.chaser_views[n].win.refresh()
            self.chaser_views.pop(n)
            self._resize()

    def base_delete(self, fid):
        with self.w_lock:
            if fid not in self.w.functions:
                return "No such function"
            f = self.w.functions[fid]
            f.delete()

    def base_new(self, name, cls):
        with self.w_lock:
            f = cls(self.w, name=name)
            self.handle_enter(f.id)

    def _gather_channels(self, cr):
        with self.w_lock:
            ## Gather the affected channels
            channels = []
            for f in self.w.fixtures.values():
                for s, e in cr[0]:
                    if (s <= f.id <= e) or (e == -1 and f.id >= s):
                        break
                else:
                    continue

                for n, c in enumerate(f.channels):
                    for s, e in cr[1]:
                        if (s <= n <= e) or (e == -1 and n >= s):
                            channels.append(c)
                            break

            return channels

    def scene_set(self, cr, v):
        with self.w_lock:
            channels = self._gather_channels(cr)

            ## Set the values
            self.primitive.update({c: v for c in channels})

            ## Update the display
            self.channel_bank.set_scope(self.primitive.scope)
            if v is not None:
                self.channel_bank.set_values(((c, v) for c in channels))
            self.renderer.clear_hold()
            self.renderer.hold(self.primitive.values)

    def scene_edit(self, cr, force = False):
        with self.w_lock:

            channels = self._gather_channels(cr)
            if not force:
                channels = [c for c in channels if c in self.primitive.scope]
            else:
                self.primitive.update({c: 0 for c in channels if c not in self.primitive.scope})

            if not channels:
                return "No channels given"

            curses.curs_set(0)
            values = self.primitive.values

            self.channel_bank.set_active(channels, True)

            while True:
                self.channel_bank.set_scope(self.primitive.scope)
                self.channel_bank.set_values(((c, v) for c, v in values.items()))
                self.renderer.clear_hold()
                self.renderer.hold(self.primitive.values)

                l = self.pager.win.getch()
                delta = 0

                if l == curses.KEY_RESIZE:
                    self._resize()
                elif l == ord('q'):
                    break
                elif l in (ord('j'), curses.KEY_DOWN):
                    delta = -5
                elif l in (ord('k'), curses.KEY_UP):
                    delta = 5
                elif l == ord('h'):
                    delta = -1
                elif l == ord('l'):
                    delta = 1
                elif l == curses.KEY_NPAGE:
                    delta = 25
                elif l == curses.KEY_PPAGE:
                    delta = -25
                elif l == curses.KEY_HOME:
                    delta = 255
                elif l == curses.KEY_END:
                    delta = -255

                if delta != 0:
                    for c in channels:
                        values[c] = max(0, min(255, values[c]+delta))
                        self.primitive.update(values)

            self.channel_bank.set_active(channels, False)

            curses.curs_set(1)

    def scene_clear(self, cr):
        self.scene_set(cr, None)

    def scene_exit(self):
        self.primitive = None
        
        self.handle_exit()

    def audio_exit(self):
        self.primitive = None

        self.handle_exit()

    def handle_exit(self):
        for c in self.chaser_views:
            c.highlight = False

        if self.current_cv is not None:
            self.current_cv.selected = None

        self.channel_bank.highlight = False

        if self.chaser_stack:
            ## Load the previous chaser
            c, sel = self.chaser_stack.pop(-1)

            if True not in (True for i in self.chaser_views if i.chaser.id == c.id):
                ## We need to load it
                ## Check if we have one for the current chaser
                try:
                    idx = [i.chaser.id for i in self.chaser_views].index(self.chaser.id)
                except (ValueError, AttributeError):
                    ## We don't have it
                    if len(self.chaser_views) == 2:
                        ## We don't have room for it, just replace the last one
                        self.chaser_views[1].set_chaser(c, sel)
                    else:
                        self.base_add(c.id)
                    self.current_cv = self.chaser_views[-1]
                else:
                    self.chaser_views[idx].set_chaser(c, sel)
                    self.current_cv = self.chaser_views[idx]
            
            self.current_cv.highlight = True
            self.current_cv.selected = sel
            if c.type == CHASER:
                self.input.context = self.context_chaser
            else:
                self.input.context = self.context_join
            self.chaser = c
        else:
            if isinstance(self.channel_bank, AudioView):
                (hw, yx), *_ = self._compute_sizes(*self.stdscr.getmaxyx())
                self.channel_bank = ChannelBank(*yx, *hw)
            self.channel_bank.set_scope(())
            self.channel_bank.title = "Channels"

            self.input.context = self.context_base
            self.chaser = None
            self.current_cv = None
            self.renderer.clear_hold()

    def base_save(self, path=None):
        with self.w_lock:
            if path is not None:
                self.path = path
            if self.path is None:
                return "No path set"
            self.w.modified = dt.datetime.now()
            self.w.save(self.path)

            return "Saved to "+self.path

    def base_quit(self):
        if askyesnocancel(self.stdscr, "Really exit?"):
            quit()
        else:
            self._resize()

    def list_fixtures(self):
        with self.w_lock:
            td = ["FIXTURES:"]
            for f in sorted(self.w.fixtures.values(), key=lambda a: a.id):
                td.append("- %03d: %s" % (f.id, f.name))
                for c in f.channels:
                    td.append("  %03d-%03d: %s" % (f.id, c.id, c.name))
            self.pager.display_many(td, split=True)

    def list_functions(self, typ):
        with self.w_lock:
            td = [typ.upper()+"S:"]
            for f in sorted(self.w.functions.values(), key=lambda a: a.id):
                if f.type == typ:
                    td.append("- %03d: %s" % (f.id, f.name))
            self.pager.display_many(td, split=True)

    def page(self):
        self.pager.user_page()

    def page_clear(self):
        self.pager.clear()

    def help(self, name, commands, help_):
        if name is None:
            dname = "MODE HELP:"
        else:
            dname = name.upper() + " COMMAND:"

        todisp = [dname, ""]
        if commands:
            if name is None:
                todisp.append("Available commands:")
            else:
                todisp.append("Available forms:")
            todisp.extend(("- "+i for i in commands))
            todisp.append("")
        
        todisp.extend(help_.split('\n'))

        self.pager.display_many(todisp, split=True)

    def chaser_select(self, num):
        with self.w_lock:
            if num < 1 or num > len(self.current_cv.chaser.steps):
                return "Out of range"
            
            self.current_cv.selected = num - 1
            s = self.current_cv.chaser.steps[num-1]
            if (s.type == CHASERSTEP and s.function is not None and s.function.type in (SCENE, AUDIO,)) or s.type in (SCENE, AUDIO,):
                self.handle_show(s.function if s.type == CHASERSTEP else s)

    def chaser_edit(self, num=None):
        with self.w_lock:
            if num is not None:
                r = self.chaser_select(num)
                if r is not None:
                    return r
            elif self.current_cv.selected is None:
                return "No step selected"

            c = self.current_cv.chaser.steps[self.current_cv.selected]
            if c.type == CHASERSTEP and c.function is None:
                return "No function on step"
            
            self.handle_enter(c.function.id if c.type == CHASERSTEP else c.id)

    def chaser_delete(self, num=None):
        with self.w_lock:
            if num is not None:
                r = self.chaser_select(num)
                if r is not None:
                    return r
            elif self.current_cv.selected is None:
                return "No step selected"

            c = self.current_cv.chaser
            s = c.steps[self.current_cv.selected]
            sel = self.current_cv.selected
            with CURSES_LOCK:
                if c.type == CHASER:
                    if askyesnocancel(self.stdscr, "Really delete step %d?" % (s.index+1), resize=self._resize):
                        sel = s.index
                        s.delete()
                    else:
                        return
                else:
                    c.delete_step(s)
                        
                if not c.steps:
                    sel = None
                else:
                    sel = max(0, sel-1)
                self.current_cv.set_chaser(c, sel)
                self._resize()

    def chaser_fade(self, t, out=False):
        with self.w_lock:
            if self.current_cv.selected is None:
                return "No step selected"
            c = self.current_cv.chaser
            s = c.steps[self.current_cv.selected]
            if out:
                s.fade_out = t
            else:
                s.fade_in = t
            self.current_cv.set_chaser(c, s.index)

    def chaser_duration(self, t):
        with self.w_lock:
            if self.current_cv.selected is None:
                return "No step selected"
            c = self.current_cv.chaser
            s = c.steps[self.current_cv.selected]
            if s.duration_mode != MANUAL:
                s.duration_mode = MANUAL
            s.duration = t
            self.current_cv.set_chaser(c, s.index)

    def chaser_unset(self):
        with self.w_lock:
            if self.current_cv.selected is None:
                return "No step selected"
            c = self.current_cv.chaser
            s = c.steps[self.current_cv.selected]
            s.duration_mode = INHERIT
            self.current_cv.set_chaser(c, s.index)

    def chaser_new(self, index, name, fid=None):
        with self.w_lock:
            if fid is not None:
                if fid not in self.w.functions:
                    return "No such function"
                f = self.w.functions[fid]
                if f.type not in (SCENE, AUDIO, CHASER, JOIN):
                    return "Invalid function"
            else:
                f = None
            
            c = self.current_cv.chaser

            if c.type == CHASER:
                if name is None and f is not None:
                    name = "Step \"%s\"" % f.name
                s = ChaserStep(c, index=index, name=name, function=f)
                self.current_cv.set_chaser(c, s.index)
            else:
                if f.id in (i.id for i in c.steps):
                    return "Already added"
                c.add_step(f)
                self.current_cv.set_chaser(c, len(c.steps)-1)
            #self.chaser_edit(s.index+1)

    def chaser_new_new(self, index, name, fname, type_):
        with self.w_lock:
            if name is None and f is not None:
                name = "Step \"%s\"" % f.name

            f = type_(self.w, name=fname)

            return self.chaser_new(index, name, fid=f.id)

    def chaser_rename(self, name):
        with self.w_lock:
            if self.current_cv.selected is None:
                return "No step selected"
            c = self.current_cv.chaser
            s = c.steps[self.current_cv.selected]
            s.name = name
            
            self.current_cv.set_chaser(c, s.index)

    def chaser_bind(self, fid):
        with self.w_lock:
            if self.current_cv.selected is None:
                return "No step selected"
            c = self.current_cv.chaser
            s = c.steps[self.current_cv.selected]

            if fid not in self.w.functions:
                return "No such function"
            f = self.w.functions[fid]
            if f.type not in (SCENE, AUDIO, CHASER, JOIN):
                return "Invalid function"

            s.function = f

            self.current_cv.set_chaser(c, s.index)
            self.chaser_select(s.index+1)
    
    def chaser_move(self, a, b = None):
        with self.w_lock:
            cursel = self.current_cv.selected 
            if cursel is not None:
                cursel = self.current_cv.chaser.steps[cursel]
            if b is not None:
                sel = a - 1
                if sel < 0 or sel >= len(self.current_cv.chaser.steps):
                    return "Invalid selection"
                to = b - 1
            else:
                to = a - 1
                if self.current_cv.selected is None:
                    return "No step selected"
                sel = self.current_cv.selected
            if to < 0 or to >= len(self.current_cv.chaser.steps):
                return "Invalid destination"
            c = self.current_cv.chaser
            s = c.steps[sel]
            s.index = to
            
            self.current_cv.set_chaser(c, cursel.index if cursel is not None else None)

    def primitive_rename(self, name):
        with self.w_lock:
            self.primitive.name = name
            self.channel_bank.title = self.primitive.type + ' "%s"' % name

    def chaser_rename_self(self, name):
        with self.w_lock:
            c = self.current_cv.chaser
            c.name = name

            self.current_cv.set_chaser(c, self.current_cv.selected)

    def audio_fade(self, t, out=False):
        with self.w_lock:
            if out:
                self.primitive.fade_out = t
            else:
                self.primitive.fade_in = t
            self.channel_bank.audio = self.primitive

    def audio_filename(self, fname):
        with self.w_lock:
            self.primitive.filename = fname
            self.channel_bank.audio = self.primitive

    def _render_callback(self, t, values):
        if not self.rendering:
            return
        with self.w_lock, CURSES_LOCK:
            syx = self.input.win.getyx()

            self.channel_bank.set_values(values)
            self.channel_bank.title = "LIVE: %7.2fs" % t

            for d, cv in zip(self.renderer._data, (i for i in self.chaser_views if i.chaser.type == CHASER)):
                cv.selected = d.steps[-1].index if d.steps else None

            self.input.win.move(*syx)

    def base_run(self):
        if not self.chaser_views:
            return "No chasers loaded"

        self.channel_bank.set_scope(self._channels)
        self.channel_bank.title = "LIVE: %7.2fs" % 0
        self.channel_bank.highlight = True

        self.rendering = True
        self.renderer.set_functions(*((cv.chaser, cv.chaser.get_data(cv.selected)) for cv in self.chaser_views if cv.chaser.type == CHASER))
        self.renderer.start()

        self.input.context = self.context_run

        return "Started running"

    def chaser_run(self):
        self.current_cv.highlight = False
        self.renderer.clear_hold()
        self.chaser_stack.append([c.selected for c in self.chaser_views])
        self.handle_show(None)
        self.base_run()

    def run_exit(self):
        self.rendering = False
        self.renderer.stop()

        with self.w_lock:
            self.channel_bank.title = "Channels"
            self.channel_bank.highlight = False
            self.channel_bank.set_scope(())

            if self.chaser_stack:
                for i, c in zip(self.chaser_stack.pop(-1), self.chaser_views):
                    c.selected = i
                self.current_cv.highlight = True
                if self.current_cv.selected is not None:
                    s = self.current_cv.chaser.steps[self.current_cv.selected]
                    if s.function is not None and s.function.type in (SCENE, AUDIO,):
                        self.handle_show(s.function)
                self.input.context = self.context_chaser
            else:
                self.input.context = self.context_base

                for cv in self.chaser_views:
                    cv.selected = None

    def run_jump(self, n, p, index):
        if not index:
            n = [j for j, i in enumerate(self.chaser_views) if i.chaser.id == n]
            if not n:
                return "No such chaser loaded"
            n = n[0]
        if n >= len(self.chaser_views) or n < 0:
            return "Chaser index out of range"
        if p is not None and (p < 1 or p > len(self.chaser_views[n].chaser.steps)):
            return "Step index out of range"
        self.renderer.advance((n, (p-1) if p is not None else p))

    def run_advance_all(self):
        for c in self.chaser_views:
            self.renderer.advance((c.chaser.id, None))

    def current_status(self):
        self.pager.display_many((
            "CURRENT STATUS",
            "Output is %sOK: %s" % ("" if self.output.ok else "NOT ", self.output.status),
        ), True)

    def chaser_info(self, n):
        with self.w_lock:
            if n is None:
                n = self.current_cv.selected 
                if n is None:
                    return "No step selected"
            else:
                n -= 1
                if n < 0 or n >= len(self.current_cv.chaser.steps):
                    return "Invalid step"
            f = self.current_cv.chaser.steps[n]
            self.pager.display_many((
                f.name,
                "-  Fade in: %7.3f" % (f.fade_in/1000),
                "- Duration: " + (("%7.3f" % (f.duration/1000)) if f.duration != INFTY else "infty"),
                "- Fade out: %7.3f" % (f.fade_out/1000),
            ))

    def chaser_mode(self, mode):
        with self.w_lock:
            self.current_cv.chaser.advance_mode = mode
            self.current_cv.set_chaser(self.current_cv.chaser, self.current_cv.selected)

    def base_copy(self, name, num):
        with self.w_lock:
            ## TODO: Implement this in BLC
            if num not in self.w.functions:
                return "No such function"
            f = self.w.functions[num]
            if f.type != SCENE:
                return "Can only close scenes"
            f2 = Scene(self.w, name=name, values=f.values)
            self.handle_enter(f2.id)

    def __init__(self, path, output):
        ## Have to do most of the actual initialization in the main method, as curses isn't
        ## ready yet.
        self.channel_bank = None
        self.input = None
        self.pager = None
        self.stdscr = None

        self.primitive = None
        self.chaser = None
        self.current_cv = None

        self.path = path
        self._w_created = False
        if path is None or not os.path.isfile(path):
            self.w = Workspace("", "", 0, dt.datetime.now())
            self._w_created = True
        else:
            self.w = Workspace.load(path)

        self.w_lock = threading.RLock()

        self.chaser_views = []

        self.chaser_stack = []

        self.context_base = Input.parse_context((
            ("edit $num", self.handle_enter),
            ("edit", lambda: self.handle_enter(None)),
            ("delete $num", self.base_delete),
            ("new scene $quoted_string", lambda n: self.base_new(n, Scene)),
            ("new chaser $quoted_string", lambda n: self.base_new(n, Chaser)),
            ("new audio $quoted_string", lambda n: self.base_new(n, Audio)),
            ("new join $quoted_string", lambda n: self.base_new(n, Join)),

            ("add $num", self.base_add),
            ("subtract $letter", lambda n: self.base_remove(n, True)),
            ("subtract $num", lambda n: self.base_remove(n, False)),

            ("run", self.base_run),

            ("write", self.base_save),
            ("write $quoted_string", self.base_save),

            ("list fixtures", self.list_fixtures),
            ("list scenes", lambda: self.list_functions(SCENE)),
            ("list chasers", lambda: self.list_functions(CHASER)),
            ("list audio", lambda: self.list_functions(AUDIO)),
            ("list joins", lambda: self.list_functions(JOIN)),

            ("new scene $quoted_string from $num", self.base_copy),

            ("currentstatus", self.current_status),

            ("pager page", self.page), 
            ("pager clear", self.page_clear),
            ("quit", self.base_quit),
        ), {
            None: "This is the base edit mode for editing functions.",
            "edit": "Edit the specified function.",
            "delete": "Delete the specified function.",
            "new": "Create a new function of the given type.",
            "write": "Save the workspace. The path is implicitly the one loaded from if not given.",
            "list": "List available fixtures or functions.",
            "pager": "Control the pager. In page mode, arrow keys, page up/down, home/end, and j/k can be used to scroll, q exits.",
            "quit": "Exit BLC.",
            "remove": "Remove the specified chaser from the display. If a letter is used, remove the chaser at the given position, where 'a' is the left-most chaser and so forth. If a number is used, treat it as a chaser ID.",
            "add": "Add a chaser to the display. Currently a limit of 2 visible.",
            "currentstatus" : "Display information about the system's current status."
        }, self.help)

        self.context_chaser = Input.parse_context((
            ("choose $num", self.chaser_select),

            ("edit", self.chaser_edit),
            ("edit $num", self.chaser_edit),

            ("delete", self.chaser_delete),
            ("delete $num", self.chaser_delete),

            ("append $quoted_string", lambda n: self.chaser_new(-1, n)),
            ("append $quoted_string from $num", lambda n, s: self.chaser_new(-1, n, s)),
            ("append $quoted_string from new scene $quoted_string", lambda n, s: self.chaser_new_new(-1, n, s, Scene)),
            ("append $quoted_string from new audio $quoted_string", lambda n, s: self.chaser_new_new(-1, n, s, Audio)),

            ("append", lambda: self.chaser_new(-1, "")),
            ("append from $num", lambda s: self.chaser_new(-1, "", s)),
            ("append from new scene $quoted_string", lambda s: self.chaser_new_new(-1, "", s, Scene)),
            ("append from new audio $quoted_string", lambda s: self.chaser_new_new(-1, "", s, Audio)),

            ("new $num $quoted_string", self.chaser_new),
            ("new $num $quoted_string from $num", self.chaser_new),
            ("new $num $quoted_string from new scene $quoted_string", lambda i, n, s: self.chaser_new_new(i, n, s, Scene)),
            ("new $num $quoted_string from new audio $quoted_string", lambda i, n, s: self.chaser_new_new(i, n, s, Audio)),

            ("rename $quoted_string", self.chaser_rename),
            ("rename chaser $quoted_string", self.chaser_rename_self),
            ("move $num to $num", self.chaser_move),
            ("move $num", self.chaser_move),
            ("set fade in $time", self.chaser_fade),
            ("set fade out $time", lambda t: self.chaser_fade(t, True)),
            ("set mode oneshot", lambda: self.chaser_mode(ONESHOT)),
            ("set mode loop", lambda: self.chaser_mode(LOOP)),
            ("set length $time", self.chaser_duration),
            ("unbind", self.chaser_unset),
            ("bind $num", self.chaser_bind),

            ("list fixtures", self.list_fixtures),
            ("list scenes", lambda: self.list_functions(SCENE)),
            ("list chasers", lambda: self.list_functions(CHASER)),
            ("list audio", lambda: self.list_functions(AUDIO)),
            ("list joins", lambda: self.list_functions(JOIN)),

            ("info", lambda: self.chaser_info(None)),
            ("info $num", self.chaser_info),

            ("trailer", self.chaser_run),

            ("pager page", self.page), 
            ("pager clear", self.page_clear),
            ("quit", self.handle_exit),
        ), {
            None: "This mode is for editing chasers. All functions (excepting select) which take a number as an argument may be called without to act on the currently selected step.",
            "edit": "Edit the given step.",
            "select": "Select a step.",
            "fade": "Change the fade durations for the selected step.",
            "length": "Set the duration for the selected step.",
            "new": "Create a new step at the given position with the given name. Can also create a new function to use for the scene. Immediately enters edit mode for that step.",
            "delete": "Remove the given step.",
            "rename": "Rename the current step.",
            "append": "Create a new step at the end of the chaser. See 'new' for details.",
            "unset": "Unset the duration of the selected step, inheriting the step's duration from its function.",
            "pager": "Control the pager. In page mode, arrow keys, page up/down, home/end, and j/k can be used to scroll, q exits.",
            "move": "Move the given step to the given position",
            "bind": "Bind the step to the given function.",
            "quit": "Return to the previous mode.", 
            "trailer": "Preview the chaser in run mode.",
        }, self.help)

        self.context_scene = Input.parse_context((
            ("set $channel_range to $value", self.scene_set),
            ("reset $channel_range", self.scene_clear),

            ("edit $channel_range", self.scene_edit),
            ("edit $channel_range force", lambda cr: self.scene_edit(cr, True)),

            ("list fixtures", self.list_fixtures),
            ("list scenes", lambda: self.list_functions(SCENE)),
            ("list chasers", lambda: self.list_functions(CHASER)),
            ("list audio", lambda: self.list_functions(AUDIO)),
            ("list joins", lambda: self.list_functions(JOIN)),

            ("rename $quoted_string", self.primitive_rename),

            ("pager page", self.page), 
            ("pager clear", self.page_clear),
            ("quit", self.scene_exit),
        ), {
            None: "This mode is for editing scene primitives for fixed lighting.",
            "set": "Set the given channel range to the given value (0 <= value <= 255).",
            "reset": "Remove the given channel range from the scene",
            "list": "List available fixtures or functions.",
            "pager": "Control the pager. In page mode, arrow keys, page up/down, home/end, and j/k can be used to scroll, q exits.",
            "edit": "Live edit scenes using the arrow keys, page up/down, home/end, and h/j/k/l. If \"force\" is used, all matching channels are edited, instead of just the matching ones already in the scope.",
            "quit": "Return to the previous mode.",
        }, self.help)

        self.context_audio = Input.parse_context((
            ("list fixtures", self.list_fixtures),
            ("list scenes", lambda: self.list_functions(SCENE)),
            ("list chasers", lambda: self.list_functions(CHASER)),

            ("rename $quoted_string", self.primitive_rename),

            ("filename $quoted_string", self.audio_filename),
            ("fade in $time", self.audio_fade),
            ("fade out $time", lambda t: self.audio_fade(t, True)),

            ("pager page", self.page), 
            ("pager clear", self.page_clear),
            ("quit", self.audio_exit),
        ), {
            None: "This mode is for editing audio primitives for single audio files.",
            "list": "List available fixtures or functions.",
            "rename": "Rename the function.",
            "filename": "Set the filename for the function.",
            "fade": "Set fade times for the function. Note that unlike lighting, fade out is done during the audio's run.",
            "pager": "Control the pager. In page mode, arrow keys, page up/down, home/end, and j/k can be used to scroll, q exits.",
            "quit": "Return to the previous mode.",
        }, self.help)

        self.context_run = Input.parse_context((
            ("quit", self.run_exit),

            ("jump $letter to $num", lambda n, p: self.run_jump(n, p, True)),
            ("jump $num to $num", lambda n, p: self.run_jump(n, p, False)),

            ("advance $letter", lambda n: self.run_jump(n, None, True)),
            ("advance $num", lambda n: self.run_jump(n, None, False)),
            ("advance", lambda: self.run_jump(0, None, True)),
            ("badvance", lambda: self.run_jump(1, None, True)),

            ("everythingadvance", self.run_advance_all()),

            ("currentstatus", self.current_status),
        ), {
            None: "This mode is for running a show or previewing a chaser.",
            "quit": "Return to the previous mode.",
            "jump": "Jump the given chaser to the given location.",
            "advance": "Advance a chaser a single step. If no letter is given, this is the first from the left.",
            "badvance": "Advance the second chaser from the left a single step.",
            "everythingadvance": "Advance all chasers a single step each.",
            "currentstatus" : "Display information about the system's current status."
        }, self.help)

        self.context_join = Input.parse_context((
            ("choose $num", self.chaser_select),

            ("edit", self.chaser_edit),
            ("edit $num", self.chaser_edit),

            ("delete", self.chaser_delete),
            ("delete $num", self.chaser_delete),

            ("add", lambda: self.chaser_new(-1, "")),
            ("add from $num", lambda s: self.chaser_new(-1, "", s)),
            ("add from new scene $quoted_string", lambda s: self.chaser_new_new(-1, "", s, Scene)),
            ("add from new audio $quoted_string", lambda s: self.chaser_new_new(-1, "", s, Audio)),

            ("rename $quoted_string", self.chaser_rename_self),

            ("list fixtures", self.list_fixtures),
            ("list scenes", lambda: self.list_functions(SCENE)),
            ("list chasers", lambda: self.list_functions(CHASER)),
            ("list audio", lambda: self.list_functions(AUDIO)),
            ("list joins", lambda: self.list_functions(JOIN)),

            ("pager page", self.page), 
            ("pager clear", self.page_clear),
            ("quit", self.handle_exit),
        ))

        self.output = output
        self.renderer = Renderer(self.w, self.w_lock, self.output, self._render_callback)
        self.rendering = False

        self._channels = sum((tuple(f.channels) for f in sorted(self.w.fixtures.values(), key=lambda i: i.id)), ())