#!/usr/bin/python3

import ply.yacc as yacc
from .lexer import operators, tokens
from .util import Token

# PARSER
precedence = (
    ('nonassoc', 'FROM'),
    ('right', 'IMPLIES'),
    ('right', 'NOT'),
    ('nonassoc', 'EQU', 'NEQU', 'EQ', 'NEQ', 'UNIV', 'IS', 'EQA', 'NEQA', 'LT', 'LE', 'GT', 'GE', 'LTL', 'LEL', 'GTL', 'GEL'),
    ('left', 'PLUS', 'MINUS'),
    ('left', 'STAR', 'DIV', 'IDIV', 'MOD'),
    ('nonassoc', 'POW'),
    ('right', 'UMINUS', 'UPLUS'),
    ('nonassoc', 'UINTEGER', 'UREAL'),
    ('nonassoc', 'NAME', 'VARIABLE', 'STRING'),
    ('nonassoc', 'PERIOD'),
    ('nonassoc', 'LBRACKET', 'RBRACKET', 'LPAREN', 'RPAREN', 'COMMA', 'SEMI', 'PIPE', 'LBRACE', 'RBRACE')
)

class Node:
    def __init__(self, type, children=None, data=None):
         self.type = type
         self.data = data
         self.children = children if children else []

    def __str__(self):
        val = self.type
        if self.children:
            val += ' ' + ' '.join([str(c) for c in self.children])
            val = '({})'.format(val)
        return val

def make_token(p, n):
    lextoken = p.slice[n]
    return Token(lextoken.type, lextoken.value, lextoken.lexpos)

def p_text_empty(p):
    'text : '
    p[0] = Node('text', [])
def p_text_clause(p):
    'text : text clause'
    p[0] = p[1]
    p[0].children.append(p[2])

def p_clause_head(p):
    'clause : head PERIOD'
    p[0] = Node('clause', [p[1], make_token(p, 2)])
def p_clause_rule(p):
    'clause : head FROM or PERIOD'
    p[0] = Node('clause', [p[1], make_token(p, 2), p[3], make_token(p, 4)])
def p_clause_error(p):
    'clause : error PERIOD'
    p[0] = Node('error')

def p_head(p):
    'head : term'
    p[0] = Node('head', [p[1]])

def p_or_single(p):
    'or : if'
    p[0] = p[1]
def p_or_if(p):
    'or : or SEMI if'
    if p[1].type == 'or':
        p[0] = p[1]
    else:
        p[0] = Node('or', [p[1]])
    p[0].children.append(make_token(p, 2))
    p[0].children.append(p[3])

def p_if_single(p):
    'if : and'
    p[0] = p[1]
def p_if_and(p):
    'if : and IMPLIES if'
    p[0] = Node('if', [p[1], make_token(p, 2), p[3]])

def p_and_single(p):
    'and : term'
    p[0] = p[1]
def p_and_term(p):
    'and : and COMMA term'
    if p[1].type == 'and':
        p[0] = p[1]
    else:
        p[0] = Node('and', [p[1]])
    p[0].children.append(make_token(p, 2))
    p[0].children.append(p[3])

def p_term_functor(p):
    'term : functor LPAREN args RPAREN'
    # No whitespace allowed between functor and LPAREN.
    t2 = make_token(p, 2)
    if p[1].children[0].pos + len(p[1].children[0].val) < t2.pos:
        raise SyntaxError('whitespace before ' + str(t2))
    p[0] = Node('term', [p[1], t2, p[3], make_token(p, 4)])
def p_term_or(p):
    'term : LPAREN or RPAREN'
    p[0] = Node('term', [make_token(p, 1), p[2], make_token(p, 3)])
def p_term_binary(p):
    '''term : term PLUS term
            | term MINUS term
            | term STAR term
            | term POW term
            | term DIV term
            | term IDIV term
            | term MOD term

            | term EQU term
            | term NEQU term
            | term EQ term
            | term NEQ term
            | term UNIV term
            | term IS term
            | term EQA term
            | term NEQA term
            | term LT term
            | term LE term
            | term GT term
            | term GE term
            | term LTL term
            | term LEL term
            | term GTL term
            | term GEL term'''
    p[0] = Node('term', [p[1], make_token(p, 2), p[3]])
def p_term_unary(p):
    '''term : NOT term
            | MINUS term %prec UMINUS
            | PLUS term %prec UPLUS'''
    p[0] = Node('term', [make_token(p, 1), p[2]])
def p_term_list(p):
    'term : list'
    p[0] = Node('term', [p[1]])

def p_term_simple(p):
    '''term : STRING
            | NAME
            | UINTEGER
            | UREAL
            | VARIABLE'''
    p[0] = Node('term', [make_token(p, 1)])

def p_args_empty(p):
    'args : '
    p[0] = Node('args', [])
def p_args_single(p):
    'args : term'
    p[0] = Node('args', [p[1]])
def p_args_term(p):
    'args : args COMMA term'
    p[0] = p[1]
    p[0].children.append(make_token(p, 2))
    p[0].children.append(p[3])

def p_list_empty(p):
    'list : LBRACKET RBRACKET'
    p[0] = Node('list', [make_token(p, 1), make_token(p, 2)])
def p_list_term(p):
    'list : LBRACKET listexpr RBRACKET'
    p[0] = Node('list', [make_token(p, 1), p[2], make_token(p, 3)])
def p_listexpr_single(p):
    'listexpr : term'
    p[0] = Node('listexpr', [p[1]])
def p_listexpr_term(p):
    'listexpr : term COMMA listexpr'
    p[0] = Node('listexpr', [p[1], make_token(p, 2), p[3]])
def p_listexpr_pipe(p):
    'listexpr : term PIPE term'
    p[0] = Node('listexpr', [p[1], make_token(p, 2), p[3]])

def p_functor(p):
    'functor : NAME'
    p[0] = Node('functor', [make_token(p, 1)])

def p_error(p):
    print('Syntax error in input: ' + str(p))

parser = yacc.yacc()

if __name__ == '__main__':
    while True:
        try:
            s = input('> ')
        except EOFError:
            break
        if not s:
            continue
        ast = parser.parse(s)
        print(ast)