# SPDX-License-Identifier: MIT
# Copyright 2021 Jookia <contact@jookia.org>

import parse

def text_create(value):
    return ("text", value)
def text_value(object):
    return object[1]
def text_dispatch(object, verb, args):
    value = text_value(object)
    if verb == "Append":
        appendix = text_value(args[0])
        return text_create(value + " " + appendix)
    return None

def module_create(verbs):
    return ("module", verbs)
def module_dispatch(object, verb, args):
    (type, functions) = object
    return functions[verb](object, args)

def do_system_print(subject, args):
    print(text_value(args[0]))
    return None
def do_system_read(subject, args):
    return text_create(input())
system_module = module_create({
    "Print": do_system_print,
    "Read": do_system_read,
})

def resolve_value(env, value):
    if value.__class__ == parse.Reference:
        return env[value.value]
    elif value.__class__ == parse.Text:
        return text_create(value.value)
    else:
        print("Unimplemented value: %s" % (value))

def run_statement(env, ast):
    subject = resolve_value(env, ast.subject)
    if ast.verb == None:
        return subject
    args = []
    for arg in ast.arguments:
        args.append(resolve_value(env, arg))
    if subject[0] == "text":
        return text_dispatch(subject, ast.verb, args)
    elif subject[0] == "module":
        return module_dispatch(subject, ast.verb, args)
    return None

def run_set(env, ast):
    env[ast.subject] = run_statement(env, ast.statement)
    return env[ast.subject]

def run_if(env, ast):
    print("Unimplemented if")
    return None

def run_command(env, ast):
    if ast.__class__ == parse.Statement:
        return run_statement(env, ast)
    elif ast.__class__ == parse.Set:
        return run_set(env, ast)
    elif ast.__class__ == parse.Conditional:
        return run_if(env, ast)
    else:
        print("Unknown command %s" % (ast))
        return None

def run_ast(ast):
    env = {
        "System": system_module,
    }
    for command in ast:
        run_command(env, command)