exit_commands = ['exit', 'abort', 'quit', 'bye', 'eat flaming death', 'q']
help_commands = ['help', '?']
context_commands = ['what', '??']
local_help_commands = ['help!', '???']

class Menu():
	def __init__(self, name, items=[], prompt='> ',
		     return_index=True,
		     exit_msg=None, exit_confirm_msg=None, exit_disallowed_msg=None,
		     help_text=None, uses_db=False):
		self.name = name
		self.items = items
		self.prompt = prompt
		self.return_index = return_index
		self.exit_msg = exit_msg
		self.exit_confirm_msg = exit_confirm_msg
		self.exit_disallowed_msg = exit_disallowed_msg
		self.help_text = help_text
		self.context = None
		self.header_format = '[%s]'
		self.uses_db = uses_db

	def exit_menu(self):
		if self.exit_disallowed_msg != None:
			print self.exit_disallowed_msg
			return
		if self.exit_confirm_msg != None:
			if not self.confirm(self.exit_confirm_msg, default=True):
				return
		raise ExitMenu()

	def at_exit(self):
		if self.exit_msg:
			print self.exit_msg

	def set_context(self, string, display=True):
		self.context = string
		if self.context != None and display:
			print self.context

	def add_to_context(self, string):
		self.context += string

	def printc(self, string):
		print string
		if self.context == None:
			self.context = string
		else:
			self.context += '\n' + string

	def show_context(self):
		print self.header_format % self.name
		if self.context != None:
			print self.context

	def item_is_submenu(self, i):
		return isinstance(self.items[i], Menu)

	def item_name(self, i):
		if self.item_is_submenu(i):
			return self.items[i].name
		elif isinstance(self.items[i], tuple):
			return self.items[i][1]
		else:
			return self.items[i]

	def item_value(self, i):
		if isinstance(self.items[i], tuple):
			return self.items[i][0]
		if self.return_index:
			return i
		return self.items[i]

	def input_str(self, prompt=None, regex=None, length_range=(None,None),
		      empty_string_is_none=False):
		if regex != None:
			while True:
				result = self.input_str(prompt, length_range=length_range,
							empty_string_is_none=empty_string_is_none)
				if result == None or re.match(regex+'$', result):
					return result
				else:
					print 'Value must match regular expression "%s"' % regex
		if length_range != (None,None):
			while True:
				result = self.input_str(prompt, empty_string_is_none=empty_string_is_none)
				if result == None:
					length = 0
				else:
					length = len(result)
				if ((length_range[0] and length < length_range[0]) or
				    (length_range[1] and length > length_range[1])):
					if length_range[0] and length_range[1]:
						print 'Value must have length in range [%d,%d]' % length_range
					elif length_range[0]:
						print 'Value must have length at least %d' % length_range[0]
					else:
						print 'Value must have length at most %d' % length_range[1]
				else:
					return result
		if prompt == None:
			prompt = self.prompt
		while True:
			try:
				result = unicode(raw_input(safe_str(prompt)),
						 conf.input_encoding)
			except EOFError:
				print 'quit'
				self.exit_menu()
				continue
			if result in exit_commands:
				self.exit_menu()
				continue
			if result in help_commands:
				self.general_help()
				continue
			if result in local_help_commands:
				self.local_help()
				continue
			if result in context_commands:
				self.show_context()
				continue
#			if result in faq_commands:
#				FAQMenu().execute()
#				continue
#			if result in restart_commands:
#				if self.confirm('Restart Dibbler?'):
#					restart()
#				continue
			if empty_string_is_none and result == '':
				return None
			return result

	def input_int(self, prompt=None, allowed_range=(None,None)):
		if prompt == None:
			prompt = self.prompt
		while True:
			result = self.input_str(prompt)
			try:
				value = int(result)
				if ((allowed_range[0] and value < allowed_range[0]) or
				    (allowed_range[1] and value > allowed_range[1])):
					if allowed_range[0] and allowed_range[1]:
						print 'Value must be in range [%d,%d]' % allowed_range
					elif allowed_range[0]:
						print 'Value must be at least %d' % allowed_range[0]
					else:
						print 'Value must be at most %d' % allowed_range[1]
				else:
					return value
			except ValueError:
				print 'Please enter an integer'

#	def input_user(self, prompt=None):
#		user = None
#		while user == None:
#			user = self.retrieve_user(self.input_str(prompt))
#		return user

#	def retrieve_user(self, search_str):
#		return self.search_ui(search_user, search_str, 'user')

#	def input_product(self, prompt=None):
#		product = None
#		while product == None:
#			product = self.retrieve_product(self.input_str(prompt))
#		return product

#	def retrieve_product(self, search_str):
#		return self.search_ui(search_product, search_str, 'product')

#	def input_thing(self, prompt=None, permitted_things=('user','product'),
#			add_nonexisting=(), empty_input_permitted=False):
#		result = None
#		while result == None:
#			search_str = self.input_str(prompt)
#			if search_str == '' and empty_input_permitted:
#				return None
#			result = self.search_for_thing(search_str, permitted_things, add_nonexisting)
#		return result

#	def search_for_thing(self, search_str, permitted_things=('user','product'),
#			     add_nonexisting=()):
#		search_fun = {'user': search_user,
#			      'product': search_product}
#		results = {}
#		result_values = {}
#		for thing in permitted_things:
#			results[thing] = search_fun[thing](search_str, self.session)
#			result_values[thing] = self.search_result_value(results[thing])
#		selected_thing = argmax(result_values)
#		if results[selected_thing] == []:
#			thing_for_type = {'card': 'user', 'username': 'user',
#					  'bar_code': 'product'}
#			type_guess = guess_data_type(search_str)
#			if type_guess != None and thing_for_type[type_guess] in add_nonexisting:
#				return self.search_add(search_str)
#			print 'No match found for "%s".' % search_str
#			return None
#		return self.search_ui2(search_str, results[selected_thing], selected_thing)

	def search_result_value(self, result):
		if result == None:
			return 0
		if not isinstance(result, list):
			return 3
		if len(result) == 0:
			return 0
		if len(result) == 1:
			return 2
		return 1

	def search_add(self, string):
		type_guess = guess_data_type(string)
		if type_guess == 'username':
			print '"%s" looks like a username, but no such user exists.' % string
			if self.confirm('Create user %s?' % string):
				user = User(string, None)
				self.session.add(user)
				return user
			return None
		if type_guess == 'card':
			selector = Selector('"%s" looks like a card number, but no user with that card number exists.' % string,
					    [('create', 'Create user with card number %s' % string),
					     ('set', 'Set card number of an existing user to %s' % string)])
			selection = selector.execute()
			if selection == 'create':
				username = self.input_str('Username for new user (should be same as PVV username)> ',
							  User.name_re, (1,10))
				user = User(username, string)
				self.session.add(user)
				return user
			if selection == 'set':
				user = self.input_user('User to set card number for> ')
				old_card = user.card
				user.card = string
				print 'Card number of %s set to %s (was %s)' % (user.name, string, old_card)
				return user
			return None
		if type_guess == 'bar_code':
			print '"%s" looks like the bar code for a product, but no such product exists.' % string
			return None


	def search_ui(self, search_fun, search_str, thing):
		result = search_fun(search_str, self.session)
		return self.search_ui2(search_str, result, thing)

	def search_ui2(self, search_str, result, thing):
		if not isinstance(result, list):
			return result
		if len(result) == 0:
			print 'No %ss matching "%s"' % (thing, search_str)
			return None
		if len(result) == 1:
			msg = 'One %s matching "%s": %s.  Use this?' %\
			      (thing, search_str, unicode(result[0]))
			if self.confirm(msg, default=True):
				return result[0]
			return None
		limit = 9
		if len(result) > limit:
			select_header = '%d %ss matching "%s"; showing first %d' % \
			    (len(result), thing, search_str, limit)
			select_items = result[:limit]
		else:
			select_header = '%d %ss matching "%s"' % \
			    (len(result), thing, search_str)
			select_items = result
		selector = Selector(select_header, items=select_items,
				    return_index=False)
		return selector.execute()



	def confirm(self, prompt, default=None):
		return ConfirmMenu(prompt, default).execute()

	def print_header(self):
		print
		print self.header_format % self.name

	def pause(self):
		self.input_str('.')

	def general_help(self):
		print '''
DIBBLER HELP

The following commands are recognized (almost) everywhere:

 help, ?          -- display this help
 what, ??         -- redisplay the current context
 help!, ???       -- display context-specific help (if any)
 faq              -- display frequently asked questions (with answers)
 exit, quit, etc. -- exit from the current menu

When prompted for a user, you can type (parts of) the user name or
card number.  When prompted for a product, you can type (parts of) the
product name or barcode.

About payment and "credit": When paying for something, use either
Dibbler or the good old money box -- never both at the same time.
Dibbler keeps track of a "credit" for each user, which is the amount
of money PVVVV owes the user.  This value decreases with the
appropriate amount when you register a purchase, and you may increase
it by putting money in the box and using the "Adjust credit" menu.
'''

	def local_help(self):
		if self.help_text == None:
			print 'no help here'
		else:
			print
			print 'Help for %s:' % (self.header_format%self.name)
			print self.help_text

	def execute(self):
		self.set_context(None)
		try:
			if self.uses_db:
				self.session = Session()
			else:
				self.session = None
			return self._execute()
		except ExitMenu:
			self.at_exit()
			return None
		finally:
			if self.session != None:
				self.session.close()
				self.session = None

	def _execute(self):
		line_format = '%' + str(len(str(len(self.items)))) + 'd ) %s'
		while True:
			self.print_header()
			self.set_context(None)
			if len(self.items)==0:
				self.printc('(empty menu)')
				self.pause()
				return None
			for i in range(len(self.items)):
				self.printc(line_format % (i+1, self.item_name(i)))
			item_i = self.input_int(self.prompt, (1,len(self.items)))-1
			if self.item_is_submenu(item_i):
				self.items[item_i].execute()
			else:
				return self.item_value(item_i)


class Selector(Menu):
	def __init__(self, name, items=[], prompt='select> ',
		     return_index=True,
		     exit_msg=None, exit_confirm_msg=None,
		     help_text=None):
		Menu.__init__(self, name, items, prompt, return_index, exit_msg)
		self.header_format = '%s'

	def print_header(self):
		print self.header_format % self.name

	def local_help(self):
		if self.help_text == None:
			print 'This is a selection menu.  Enter one of the listed numbers, or'
			print '\'exit\' to go out and do something else.'
		else:
			print
			print 'Help for selector (%s):' % self.name
			print self.help_text


class ConfirmMenu(Menu):
	def __init__(self, prompt='confirm?', default=None):
		Menu.__init__(self, 'question', prompt=prompt,
			      exit_disallowed_msg='Please answer yes or no')
		self.default=default

	def _execute(self):
		options = {True: '[y]/n', False: 'y/[n]', None: 'y/n'}[self.default]
		while True:
			result = self.input_str('%s (%s) ' % (self.prompt, options))
			result = result.lower()
			if result in ['y','yes']:
				return True
			if result in ['n','no']:
				return False
			if self.default != None and result == '':
				return self.default
			print 'Please answer yes or no'


class MessageMenu(Menu):
	def __init__(self, name, message, pause_after_message=True):
		Menu.__init__(self, name)
		self.message = message.strip()
		self.pause_after_message = pause_after_message

	def _execute(self):
		self.print_header()
		print
		print self.message
		if self.pause_after_message:
			self.pause()