from graphviz import Digraph

def grammar_diagram(grammar):
    dot = Digraph('grammar')
    prods = grammar['productions']
    for k in prods.keys():
        dot.node(str(k))
    counter = 0
    for prod in prods.values():
        for branch in prod['branches']:
            token = branch['token']

            if token['type'] == 'Nonterminal':
                children = [token['data']]
                parent = prod['name']
            else:
                terminal = token['data']
                ty = terminal['type']
                if ty == 'Seq':
                    children = [terminal['first'], terminal['second']]
                    label = ';'
                elif ty == 'If':
                    if terminal['else_'] is not None:
                        children = [terminal['then_'], terminal['else_']]
                        label = f'if {terminal["pred"]["type"]} then else'
                    else:
                        children = [terminal['then_']]
                        label = f'if {terminal["pred"]["type"]}'
                elif ty == 'While':
                    children = [terminal['body']]
                    label = f'while {terminal["pred"]["type"]}'
                elif ty == 'Action':
                    children = []
                    label = terminal['action']['type']
                else:
                    raise Exception('??')

                counter += 1
                name = f'dummy{counter}'
                dot.node(str(name), str(label))
                dot.edge(str(prod['name']), str(name))

                parent = name
                children = [c['data'] for c in children]

            for child in children:
                dot.edge(str(parent), str(child))
    return dot

dot = grammar_diagram(best_grammar)
dot.format = 'svg'
dot.render()
dot