#!/usr/bin/env python

import logging
import os
import xml.etree.ElementTree
from dataclasses import dataclass
from typing import List, MutableMapping

from lark import Lark
from lark.visitors import Discard, Transformer, v_args

try:
    from .types import (AttributeRequirement, ClusterCommandRequirement, ClusterRequirement, RequiredAttributesRule,
                        RequiredCommandsRule)
except ImportError:
    import sys

    sys.path.append(os.path.join(os.path.abspath(
        os.path.dirname(__file__)), "..", ".."))
    from matter_idl.lint.types import (AttributeRequirement, ClusterCommandRequirement, ClusterRequirement, RequiredAttributesRule,
                                       RequiredCommandsRule)


class ElementNotFoundError(Exception):
    def __init__(self, name):
        super().__init__(f"Could not find {name}")


def parseNumberString(n: str) -> int:
    if n.startswith('0x'):
        return int(n[2:], 16)
    else:
        return int(n)


@dataclass
class RequiredAttribute:
    name: str
    code: int


@dataclass
class RequiredCommand:
    name: str
    code: int


@dataclass
class DecodedCluster:
    name: str
    code: int
    required_attributes: List[RequiredAttribute]
    required_commands: List[RequiredCommand]


def DecodeClusterFromXml(element: xml.etree.ElementTree.Element):
    if element.tag != 'cluster':
        logging.error("Not a cluster element: %r" % element)
        return None

    # cluster elements contain among other children
    #  - name (general name for this cluster)
    #  - code (unique identifier, may be hex or numeric)
    #  - attribute with side, code and optional attributes
    try:
        name = element.find('name')
        if name is None or not name.text:
            raise ElementNotFoundError('name')

        name = name.text.replace(' ', '')
        required_attributes = []
        required_commands = []

        for attr in element.findall('attribute'):
            if attr.attrib['side'] != 'server':
                continue

            if 'optional' in attr.attrib and attr.attrib['optional'] == 'true':
                continue

            # when introducing access controls, the content of attributes may either be:
            # <attribute ...>myName</attribute>
            # or
            # <attribute ...><description>myName</description><access .../>...</attribute>
            attr_name = attr.text
            description = attr.find('description')
            if description is not None:
                attr_name = description.text

            required_attributes.append(
                RequiredAttribute(
                    name=attr_name,
                    code=parseNumberString(attr.attrib['code'])
                ))

        for cmd in element.findall('command'):
            if cmd.attrib['source'] != 'client':
                continue

            if 'optional' in cmd.attrib and cmd.attrib['optional'] == 'true':
                continue

            required_commands.append(RequiredCommand(
                name=cmd.attrib["name"], code=parseNumberString(cmd.attrib['code'])))

        code = element.find('code')
        if code is None:
            raise Exception("Failed to find cluster code")

        return DecodedCluster(
            name=name,
            code=parseNumberString(code.text),
            required_attributes=required_attributes,
            required_commands=required_commands
        )
    except Exception:
        logging.exception("Failed to decode cluster %r" % element)
        return None


def ClustersInXmlFile(path: str):
    logging.info("Loading XML from %s" % path)

    # root is expected to be just a "configurator" object
    configurator = xml.etree.ElementTree.parse(path).getroot()
    for child in configurator:
        if child.tag != 'cluster':
            continue
        yield child


class LintRulesContext:
    """Represents a context for loadint lint rules.

    Handles:
       - loading referenced files (matter xml definitions)
       - adding linter rules as data is parsed
       - Looking up identifiers for various rules
    """

    def __init__(self):
        self._required_attributes_rule = RequiredAttributesRule(
            "Required attributes")
        self._required_commands_rule = RequiredCommandsRule(
            "Required commands")

        # Map cluster names to the underlying code
        self._cluster_codes: MutableMapping[str, int] = {}

    def GetLinterRules(self):
        return [self._required_attributes_rule, self._required_commands_rule]

    def RequireAttribute(self, r: AttributeRequirement):
        self._required_attributes_rule.RequireAttribute(r)

    def RequireClusterInEndpoint(self, name: str, code: int):
        """Mark that a specific cluster is always required in the given endpoint
        """
        if name not in self._cluster_codes:
            # Name may be a number. If this can be parsed as a number, accept it anyway
            try:
                cluster_code = parseNumberString(name)
                name = "ID_%s" % name
            except ValueError:
                logging.error("UNKNOWN cluster name %s" % name)
                logging.error("Known names: %s" %
                              (",".join(self._cluster_codes.keys()), ))
                return
        else:
            cluster_code = self._cluster_codes[name]

        self._required_attributes_rule.RequireClusterInEndpoint(ClusterRequirement(
            endpoint_id=code,
            cluster_code=cluster_code,
            cluster_name=name,
        ))

    def LoadXml(self, path: str):
        """Load XML data from the given path and add it to
           internal processing. Adds attribute requirement rules
           as needed.
        """
        for cluster in ClustersInXmlFile(path):
            decoded = DecodeClusterFromXml(cluster)

            if not decoded:
                continue

            self._cluster_codes[decoded.name] = decoded.code

            for attr in decoded.required_attributes:
                self._required_attributes_rule.RequireAttribute(AttributeRequirement(
                    code=attr.code, name=attr.name, filter_cluster=decoded.code))

            for cmd in decoded.required_commands:
                self._required_commands_rule.RequireCommand(
                    ClusterCommandRequirement(
                        cluster_code=decoded.code,
                        command_code=cmd.code,
                        command_name=cmd.name
                    ))


class LintRulesTransformer(Transformer):
    """
    A transformer capable to transform data parsed by Lark according to
    lint_rules_grammar.lark.
    """

    def __init__(self, file_name: str):
        self.context = LintRulesContext()
        self.file_name = file_name

    def positive_integer(self, tokens):
        """Numbers in the grammar are integers or hex numbers.
        """
        if len(tokens) != 1:
            raise Exception("Unexpected argument counts")

        return parseNumberString(tokens[0].value)

    @v_args(inline=True)
    def negative_integer(self, value):
        return -value

    @v_args(inline=True)
    def integer(self, value):
        return value

    def id(self, tokens):
        """An id is a string containing an identifier
        """
        if len(tokens) != 1:
            raise Exception("Unexpected argument counts")
        return tokens[0].value

    def ESCAPED_STRING(self, s):
        # handle escapes, skip the start and end quotes
        return s.value[1:-1].encode('utf-8').decode('unicode-escape')

    def start(self, instructions):
        # At this point processing is considered done, return all
        # linter rules that were found
        return self.context.GetLinterRules()

    def instruction(self, instruction):
        return Discard

    def all_endpoint_rule(self, attributes):
        for attribute in attributes:
            self.context.RequireAttribute(attribute)

        return Discard

    @v_args(inline=True)
    def load_xml(self, path):
        if not os.path.isabs(path):
            path = os.path.abspath(os.path.join(
                os.path.dirname(self.file_name), path))

        self.context.LoadXml(path)

    @v_args(inline=True)
    def required_global_attribute(self, name, code):
        return AttributeRequirement(code=code, name=name)

    @v_args(inline=True)
    def specific_endpoint_rule(self, code, *names):
        for name in names:
            self.context.RequireClusterInEndpoint(name, code)
        return Discard

    @v_args(inline=True)
    def required_server_cluster(self, id):
        return id


class Parser:
    def __init__(self, parser, file_name: str):
        self.parser = parser
        self.file_name = file_name

    def parse(self):
        data = LintRulesTransformer(self.file_name).transform(
            self.parser.parse(open(self.file_name, "rt").read()))
        return data


def CreateParser(file_name: str):
    """
    Generates a parser that will process a ".matter" file into a IDL
    """
    return Parser(
        Lark.open('lint_rules_grammar.lark', rel_to=__file__, parser='lalr', propagate_positions=True), file_name=file_name)


if __name__ == '__main__':
    # This Parser is generally not intended to be run as a stand-alone binary.
    # The ability to run is for debug and to print out the parsed AST.
    import click

    # Supported log levels, mapping string values required for argument
    # parsing into logging constants
    __LOG_LEVELS__ = {
        'debug': logging.DEBUG,
        'info': logging.INFO,
        'warn': logging.WARN,
        'fatal': logging.FATAL,
    }

    @click.command()
    @click.option(
        '--log-level',
        default='INFO',
        type=click.Choice(list(__LOG_LEVELS__.keys()), case_sensitive=False),
        help='Determines the verbosity of script output.')
    @click.argument('filename')
    def main(log_level, filename=None):
        logging.basicConfig(
            level=__LOG_LEVELS__[log_level],
            format='%(asctime)s %(levelname)-7s %(message)s',
        )

        logging.info("Starting to parse ...")
        data = CreateParser(filename).parse()
        logging.info("Parse completed")

        logging.info("Data:")
        logging.info("%r" % data)

    main(auto_envvar_prefix='CHIP')