#!/usr/bin/python

# Interactively prompts for variable values
# expected arguments are
# command [default-xml [custom-xml]]
#
# Two-steps logic:
# (1) scans all variables (todo: pass categories as arguments)
#     and prompts for value
#     current value proposed as default
#     also allows to remove site-dependent setting
# (2) epilogue : allows to
#     list the site-dependent vars with values
#     and to locally (re-)edit a variable from its shell name
#     quit with or without saving

import sys
import os
import re
import readline

from plc_config import PLCConfiguration

####################
release = "$Id"

def_main_config = "/etc/planetlab/default_config.xml"
def_site_config = "/etc/planetlab/configs/site.xml"
def_consolidated_config = "/etc/planetlab/plc_config.xml"

command_usage="""Usage: %s [default-xml [site-xml [consolidated-xml]]]
\t default-xml defaults to %s
\t site-xml defaults to %s
\t consolidated-xml defaults to %s
""" % (sys.argv[0],def_main_config,def_site_config, def_consolidated_config)

####################
variable_usage= """Special answers :
#\tShow variable comments
.\tStops prompting, return to mainloop
/\tCleans any site-defined value, reverts to default
=\tShows default value
>\tSkips to next category
?\tThis help
"""

def usage ():
    print(command_usage)
    sys.exit(1)

####################
def get_value (config,  category_id, variable_id):
    (category, variable) = config.get (category_id, variable_id)
    return variable['value']

# refrain from using plc_config's _sanitize 
def get_varname (config,  category_id, variable_id):
    (category, variable) = config.get (category_id, variable_id)
    return (category_id+"_"+variable['id']).upper()

def prompt_variable (cdef, cread, cwrite, category, variable):

    assert category.has_key('id')
    assert variable.has_key('id')

    category_id = category ['id']
    variable_id = variable['id']

    while True:
        default_value = get_value(cdef,category_id,variable_id)
        current_value = get_value(cread,category_id, variable_id)
        varname = get_varname (cread,category_id, variable_id)
        
        prompt = "== %s : [%s] " % (varname,current_value)
        try:
            answer = raw_input(prompt).strip()
        except EOFError :
            raise Exception ('BailOut')

        # no change
        if (answer == "") or (answer == current_value):
            return None
        elif (answer == "."):
            raise Exception ('BailOut')
        elif (answer == ">"):
            raise Exception ('NextCategory')
        elif (answer == "#"):
            if friendly_name is not None:
                print ("### " + friendly_name)
            if comments == None:
                print ("!!! No comment associated to %s" % varname)
            else:
                for line in comments:
                    print ("# " + line)
        elif (answer == "?"):
            print variable_usage.strip()
        elif (answer == "="):
            print ("%s defaults to %s" %(varname,default_value))
        # revert to default : remove from cwrite (i.e. site-config)
        elif (answer == "/"):
            cwrite.delete(category_id,variable_id)
            print ("%s reverted to %s" %(varname,default_value))
            return
        else:
            variable['value'] = answer
            cwrite.set(category,variable)
            return

####################
def prompt_all_variables (cdef, cread, cwrite):
    try:
        for (category_id, (category, variables)) in cread.variables().iteritems():
            print ("========== Category = %s" % category_id)
            for variable in variables.values():
                try:
                    newvar = prompt_variable (cdef, cread, cwrite, category, variable)
                except Exception, inst:
                    if (str(inst) == 'NextCategory'): break
                    else: raise
                    
    except Exception, inst:
        if (str(inst) == 'BailOut'): return
        else: raise


####################
def consolidate (main_config, site_config, consolidated_config):
    try:
        conso = PLCConfiguration (main_config)
        conso.load (site_config)
        conso.save (consolidated_config)
    except Exception, inst:
        print "Could not consolidate, %s" % (str(inst))
        return
    print ("Overwote %s\n\tfrom %s\n\tand %s"%(consolidated_config,main_config,site_config))
        
####################
def restart_plc ():
    print ("==================== Stopping plc")
    os.system("service plc stop")
    print ("==================== Starting plc")
    os.system("service plc start")

####################
mainloop_usage= """Available commands
c\tEdits commonly tuned variables
e\tEdits all variables
p\tPrints all locally-customized vars and values
e <var>\tPrompts (edit) fro variable <var>
p <var>\tShows current setting for <var>
l\tlists all known variables
w\tSaves and quit
W\tsaves, consolidates and quit
r\trestarts plc service
q\tQuits without saving
"""

re_mainloop_var="^(?P<command>[pe])[ \t]+(?P<varname>\w+)$"
matcher_mainloop_var=re.compile(re_mainloop_var)

common_variables=("PLC_NAME",
                  "PLC_ROOT_USER",
                  "PLC_ROOT_PASSWORD",
                  "PLC_MAIL_SUPPORT_ADDRESS",
                  "PLC_DB_HOST",
                  "PLC_API_HOST",
                  "PLC_WWW_HOST",
                  "PLC_BOOT_HOST",
                  "PLC_NET_DNS1",
                  "PLC_NET_DNS2")

def mainloop (cdef, cread, cwrite,main_config, site_config, consolidated_config):
    while True:
        try:
            answer = raw_input("Enter command (c for usual changes, w to save, ? for help) ").strip()
        except EOFError:
            answer =""
        if (answer == "") or (answer == "?") or (answer == "h"):
            print mainloop_usage
        elif (answer == "q"):
            # todo check confirmation
            return
        elif (answer == "e"):
            prompt_all_variables(cdef, cread, cwrite)
        elif (answer.lower() == "w"):
            try:
                cwrite.save(site_config)
            except:
                print ("Could not save -- fix write access on %s" % site_config)
                break
            print ("Wrote %s" % site_config)
            if (answer == "W"):
                consolidate(main_config, site_config, consolidated_config)
            print ("You might want to type 'r' (restart plc) or 'q' (quit)")
        elif (answer == "l"):
            print ("Config involves the following variables")
            sys.stdout.write(cread.output_variables())
        elif (answer == "p"):
            print ("Current site config")
            sys.stdout.write(cwrite.output_shell(False))
        elif (answer == "c"):
            try:
                for varname in common_variables:
                    (category,variable) = cdef.locate_varname(varname)
                    prompt_variable(cdef, cread, cwrite, category, variable)
            except Exception, inst:
                if (str(inst) != 'BailOut'):
                    raise
        elif (answer == "r"):
            restart_plc()
        else:
            groups_var = matcher_mainloop_var.match(answer)
            if (groups_var):
                command = groups_var.group('command')
                varname = groups_var.group('varname')
                (category,variable) = cdef.locate_varname(varname)
                if not category:
                    print "Unknown variable %s" % varname
                elif (command == 'p'):
                    print ("%s = %s" % (varname,get_value(cwrite,
                                                          category['id'],
                                                          variable['id'])))
                else:
                    try:
                        prompt_variable(cdef, cread, cwrite, category,variable)
                    except Exception, inst:
                        if (str(inst) != 'BailOut'):
                            raise
            else:
                print ("Unknown command >%s<" % answer)

####################
def main ():

    save = True
    command=sys.argv[0]
    argv = sys.argv[1:]
    if len(argv) == 0:
        (main_config,site_config,consolidated_config) = (def_main_config, def_site_config, def_consolidated_config)
    elif len(argv) == 1:
        (main_config,site_config,consolidated_config) = (argv[1], def_site_config, def_consolidated_config)
    elif len(argv) == 2:
        (main_config, site_config,consolidated_config)  = (argv[1], argv[2], def_consolidated_config)
    elif len(argv) == 3:
        (main_config, site_config,consolidated_config)  = argv
    else:
        usage()

    try:
        # the default settings only - read only
        cdef = PLCConfiguration(main_config)

        # in effect : default settings + local settings - read only
        cread = PLCConfiguration(main_config)

    except:
        print ("default config files not found, is myplc installed ?")
        return 1

    # local settings only, will be modified & saved
    cwrite=PLCConfiguration()
    
    try:
        cread.load(site_config)
        cwrite.load(site_config)
    except:
        cwrite = PLCConfiguration()

        print ("This is %s - %s -- Type ? at the prompt for help" %(command,release))
    mainloop (cdef, cread, cwrite,main_config, site_config, consolidated_config)
    return 0

if __name__ == '__main__':
    main()