import os
import io
import gzip
import re
import base64
import yaml
import copy
import subprocess
import sys
import zlib

import jinja2
import python_minifier
import markupsafe

from jinja2.filters import make_attrgetter
from jinja2.runtime import Undefined

import logging

logger = logging.getLogger(__name__)


@jinja2.pass_context
def option(context, attribute, default_value="", source="options"):
    """Get attribute from options data structure, default_value otherwise"""
    environment = context.environment
    options = environment.globals["_config"][source]

    if not attribute:
        return default_value

    try:
        getter = make_attrgetter(environment, attribute)
        value = getter(options)

        if isinstance(value, Undefined):
            return default_value

        return value

    except (jinja2.exceptions.UndefinedError):
        return default_value


@jinja2.pass_context
def include_raw_gz(context, files=None, gz=True, remove_comments=False):
    jenv = context.environment
    output = ""

    # For shell script we can even remove whitespaces so treat them individually
    # sed -e '2,$ {/^ *$/d ; /^ *#/d ; /^[ \t] *#/d ; /*^/d ; s/^[ \t]*// ; s/*[ \t]$// ; s/ $//}'
    for name in files:
        output = output + markupsafe.Markup(jenv.loader.get_source(jenv, name)[0])

    if remove_comments:
        # Remove full line comments but not shebang
        _re_comment = re.compile(r"^\s*#[^!]")
        _re_blank = re.compile(r"^\s*$")
        _re_keep = re.compile(r"^## template: jinja$")
        stripped_output = ""
        for curline in output.splitlines():
            if re.match(_re_blank, curline):
                continue
            elif re.match(_re_keep, curline):
                stripped_output = stripped_output + curline + "\n"
            elif re.match(_re_comment, curline):
                logger.debug("Removed {}".format(curline))
            else:
                stripped_output = stripped_output + curline + "\n"

        output = stripped_output

    if not gz:
        return output

    buf = io.BytesIO()
    f = gzip.GzipFile(mode="w", fileobj=buf, mtime=0)
    f.write(output.encode())
    f.close()

    # MaxSize is 21847
    logger.info(
        "Compressed user-data from {} to {}".format(len(output), len(buf.getvalue()))
    )
    return base64.b64encode(buf.getvalue()).decode("utf-8")


@jinja2.pass_context
def raise_helper(context, msg):
    raise Exception(msg)


# Custom tests
def regex(value="", pattern="", ignorecase=False, match_type="search"):
    """Expose `re` as a boolean filter using the `search` method by default.
    This is likely only useful for `search` and `match` which already
    have their own filters.
    """
    if ignorecase:
        flags = re.I
    else:
        flags = 0
    _re = re.compile(pattern, flags=flags)
    if getattr(_re, match_type, "search")(value) is not None:
        return True
    return False


def match(value, pattern="", ignorecase=False):
    """Perform a `re.match` returning a boolean"""
    return regex(value, pattern, ignorecase, "match")


def search(value, pattern="", ignorecase=False):
    """Perform a `re.search` returning a boolean"""
    return regex(value, pattern, ignorecase, "search")


# Custom filters
def sub(value="", pattern="", replace="", ignorecase=False):
    if ignorecase:
        flags = re.I
    else:
        flags = 0
    return re.sub(pattern, replace, value, flags=flags)


def pyminify(source):
    minified = python_minifier.awslambda(source, filename=None, entrypoint=None)
    gz_source = gz_pack(minified)

    logger.info(
        "Compressed python code from {} to {}".format(len(source), len(gz_source))
    )
    return gz_source


# From pyminifier
def gz_pack(source):
    """
    Returns 'source' as a gzip-compressed, self-extracting python script.

    .. note::

        This method uses up more space than the zip_pack method but it has the
        advantage in that the resulting .py file can still be imported into a
        python program.
    """
    out = ""
    # Preserve shebangs (don't care about encodings for this)
    first_line = source.split("\n")[0]
    if re.compile("^#!.*$").match(first_line):
        if first_line.rstrip().endswith("python"):
            first_line = first_line.rstrip()
            first_line += "3"
        out = first_line + "\n"
    compressed_source = zlib.compress(source.encode("utf-8"))
    out += "import zlib, base64\n"
    out += "exec(zlib.decompress(base64.b64decode('"
    out += base64.b64encode(compressed_source).decode("utf-8")
    out += "')))\n"
    return out


def inline_yaml(block):
    return yaml.safe_load(block)


def JinjaEnv(template_locations=[]):
    LoggingUndefined = jinja2.make_logging_undefined(logger=logger, base=Undefined)
    jenv = jinja2.Environment(
        trim_blocks=True,
        lstrip_blocks=True,
        undefined=LoggingUndefined,
        extensions=["jinja2.ext.loopcontrols", "jinja2.ext.do"],
    )

    if template_locations:
        jinja_loaders = []
        for _dir in template_locations:
            jinja_loaders.append(jinja2.FileSystemLoader(str(_dir)))
        jenv.loader = jinja2.ChoiceLoader(jinja_loaders)

    else:
        jenv.loader = jinja2.BaseLoader()

    jenv.globals["include_raw"] = include_raw_gz
    jenv.globals["raise"] = raise_helper
    jenv.globals["option"] = option

    jenv.filters["sub"] = sub
    jenv.filters["pyminify"] = pyminify
    jenv.filters["inline_yaml"] = inline_yaml

    jenv.tests["match"] = match
    jenv.tests["regex"] = regex
    jenv.tests["search"] = search

    return jenv


def read_config_file(path, variables={}):
    """reads yaml config file, passes it through jinja and returns data structre

    - OS ENV are available as {{ ENV.<VAR> }}
    - variables defined in parent configs are available as {{ <VAR> }}
    """
    jinja_variables = copy.deepcopy(variables)
    jinja_variables["ENV"] = os.environ

    if path.exists():
        logger.debug("Reading config file: {}".format(path))

        # First check for sops being present
        try:
            jenv = jinja2.Environment(
                enable_async=True,
                auto_reload=False,
                loader=jinja2.FunctionLoader(_sops_loader),
                undefined=jinja2.StrictUndefined,
                extensions=["jinja2.ext.loopcontrols"],
            )
            template = jenv.get_template(str(path))
            rendered_template = template.render(jinja_variables)
            data = yaml.safe_load(rendered_template)
            if data:
                return data

        except Exception as e:
            logger.exception("Error reading config file: {} ({})".format(path, e))
            sys.exit(1)

    return {}


def _sops_loader(path):
    """Tries to loads yaml file
    If "sops" key is detected the file is piped through sops before returned
    """
    with open(path, "r") as f:
        config_raw = f.read()
        data = yaml.safe_load(config_raw)

        if data and "sops" in data and "DISABLE_SOPS" not in os.environ:
            try:
                result = subprocess.run(
                    [
                        "sops",
                        "--input-type",
                        "yaml",
                        "--output-type",
                        "yaml",
                        "--decrypt",
                        "/dev/stdin",
                    ],
                    stdout=subprocess.PIPE,
                    input=config_raw.encode("utf-8"),
                    env=dict(os.environ, **{"AWS_SDK_LOAD_CONFIG": "1"}),
                )
            except FileNotFoundError:
                logger.exception(
                    "SOPS encrypted config {},  but unable to find sops binary! Try eg: https://github.com/mozilla/sops/releases/download/v3.5.0/sops-v3.5.0.linux".format(
                        path
                    )
                )
                sys.exit(1)

            return result.stdout.decode("utf-8")
        else:
            return config_raw