import spacy
from typing import Tuple
from spacy import displacy
from anytree import Node, RenderTree

class Pipeline:
    def __init__(
        self
    ) -> None:

        self.nlp = spacy.load("en_core_web_md")
        self.__ch_html_tree = None
        self.__ch_str_tree = None
        self.__ch_sentence = None

    def __postag(
        self,
        tk: str
    ) -> str:

        tag = ""
        plural_tags = ["NNS", "NNPS"]
        if tk.tag_ in plural_tags:
            tag = " ({}) (Plural)".format(tk.tag_)
        else:
            tag = " ({})".format(tk.tag_)
        return tag
    
    def __genSyntacticTree(
        self,
        expr: str
    ) -> Tuple[str,str]:

        doc = self.nlp(expr)
        root = next(doc.sents).root
        node = Node("" + root.text + ": (Root)" + self.__postag(root), parent=None)

        def tree(
            tk: str, 
            last_node: Node, 
            depth: int
        ) -> None:

            if tk.n_lefts + tk.n_rights > 0:
                for child in tk.children:
                    tree(
                        child, 
                        Node(
                            "" + child.text + ": " + str(depth + 1) + self.__postag(child), 
                            parent=last_node
                        ),
                        depth+1
                    )
        
        tree(root, node, 0)
        syntactic_str_tree = ""

        for pre, fill, node in RenderTree(node):
            syntactic_str_tree += """{}{}\n""".format(pre, node.name)

        syntactic_tree = displacy.render(doc, style='dep', options={'distance': 100})
        syntactic_html_tree = f"""
            <center>
                <div style='max-width: 800px; overflow-x:auto;'>
                    {syntactic_tree}
                </div>
            </center>
        """
        return syntactic_html_tree, syntactic_str_tree

    def compute(
        self,
        sentence: str
    ) -> Tuple[str,str,str]:

        error = ""
        error_template = """
            <center>
                <div class="alert alert-warning" role="alert">
                <h6><b>{}</b></h6>
                </div>
            </center>
        """
        if sentence.strip() == "":
            error = error_template.format("The sentence can not be empty!")
            return error, "", ""

        if sentence != self.__ch_sentence:
            self.__ch_sentence = sentence
            self.__ch_html_tree, self.__ch_str_tree = self.__genSyntacticTree(sentence)

        return error, self.__ch_html_tree, self.__ch_str_tree