from io import BytesIO
import json
import mimetypes
import os
from pathlib import Path

from .utils import scramble


class StaticFile:
    template_ext = ".tpl"
    template_filters = {
        b"tojson": lambda value: json.dumps(value)
    }

    def __init__(self, path):
        self.path = path
        self.mime_type = mimetypes.guess_type(self.remove_template_ext(str(path)))[0]
        self.mtime = None
        self.content = None

    def load_content(self):
        with open(self.path, "rb") as fh:
            return fh.read()

    def get(self, context_vars):
        content = self.load_content() if self.path.stat().st_mtime != self.mtime else self.content
        if self.path.suffix == self.template_ext:
            content = self.render(content, context_vars)
        self.content = content
        return content

    def render(self, content, context_vars):
        bio = BytesIO()
        pos = 0
        while True:
            new_pos = content.find(b"{{", pos)
            if new_pos < 0:
                break
            bio.write(content[pos:new_pos])
            end_pos = content.find(b"}}", new_pos)
            assert end_pos > 0
            full_tag = content[new_pos + 2:end_pos].split(b"|", 1)
            value = context_vars[full_tag[0].strip().decode()]
            if len(full_tag) == 2:
                value = self.template_filters[full_tag[1].strip()](value)
            bio.write(value.encode())
            pos = end_pos + 2
        bio.write(content[pos:])
        return bio.getvalue()

    def __str__(self):
        return f"<StaticFile at \"{os.sep.join(self.path.parts[-2:])}\" [{self.mime_type}]>"

    @classmethod
    def remove_template_ext(cls, filename):
        if filename.endswith(cls.template_ext):
            filename = filename[:-4]
        return filename


class StaticResource:
    def __init__(self, secret, current_hubapp):
        mimetypes.init()
        self.static_files = {}
        self.context_vars = {}
        self.master_uri = ""
        self.setup(secret, current_hubapp)

    def setup(self, secret, current_hubapp):
        hubapp_dir = Path(__file__).parents[1] / "hubapps" / current_hubapp
        for file in os.listdir(hubapp_dir):
            uri_file = StaticFile.remove_template_ext(file)
            if uri_file.startswith("master."):
                uri = f"/{scramble(secret, uri_file)}"
                if uri_file == "master.html":
                    self.master_uri = uri
                self.context_vars[uri_file.replace(".", "_")] = uri
            else:
                uri = f"/{uri_file}"
            self.static_files[uri] = StaticFile(hubapp_dir / file)
            if uri_file == "index.html":
                self.static_files["/"] = self.static_files[uri]

    async def on_get(self, req, resp):
        path = req.path
        index_uri = f"/index.html"
        if path == "/":
            path = index_uri
        res = self.static_files[path]
        resp.data = res.get(self.context_vars)
        resp.content_type = res.mime_type

    def add_routes(self, app):
        for uri_template in self.static_files:
            app.add_route(uri_template, self)