# Copyright lowRISC contributors.
# Licensed under the Apache License, Version 2.0, see LICENSE for details.
# SPDX-License-Identifier: Apache-2.0

from typing import Dict, List


def _yn_to_bool(yn: object) -> bool:
    yn_str = str(yn)
    if yn_str.lower() == 'yes':
        return True
    if yn_str.lower() == 'no':
        return False
    raise ValueError('Unknown yes/no value: {!r}.'.format(yn))


def _bool_to_yn(val: bool) -> str:
    return 'yes' if val else 'no'


def _to_int(val: object) -> int:
    if isinstance(val, int):
        return val
    return int(str(val))


def _check_choices(val: str, what: str, choices: List[str]) -> str:
    if val in choices:
        return val
    raise ValueError('{} is {!r}, which is not one of the expected values: {}.'
                     .format(what, val, choices))


class SourceClock:
    '''A clock source (input to the top-level)'''
    def __init__(self, raw: Dict[str, object]):
        self.name = str(raw['name'])
        self.aon = _yn_to_bool(raw['aon'])
        self.freq = _to_int(raw['freq'])

    def _asdict(self) -> Dict[str, object]:
        return {
            'name': self.name,
            'aon': _bool_to_yn(self.aon),
            'freq': str(self.freq)
        }


class DerivedSourceClock(SourceClock):
    '''A derived source clock (divided down from some other clock)'''
    def __init__(self,
                 raw: Dict[str, object],
                 sources: Dict[str, SourceClock]):
        super().__init__(raw)
        self.div = _to_int(raw['div'])
        self.src = sources[str(raw['src'])]

    def _asdict(self) -> Dict[str, object]:
        ret = super()._asdict()
        ret['div'] = str(self.div)
        ret['src'] = self.src.name
        return ret


class Group:
    def __init__(self,
                 raw: Dict[str, object],
                 sources: Dict[str, SourceClock],
                 what: str):
        self.name = str(raw['name'])
        self.src = str(raw['src'])
        self.sw_cg = _check_choices(str(raw['sw_cg']), 'sw_cg for ' + what,
                                    ['yes', 'no', 'hint'])
        if self.src == 'yes' and self.sw_cg != 'no':
            raise ValueError(f'Clock group {self.name} has an invalid '
                             f'combination of src and sw_cg: {self.src} and '
                             f'{self.sw_cg}, respectively.')

        self.unique = _yn_to_bool(raw.get('unique', 'no'))
        if self.sw_cg == 'no' and self.unique:
            raise ValueError(f'Clock group {self.name} has an invalid '
                             f'combination with sw_cg of {self.sw_cg} and '
                             f'unique set.')

        self.clocks = {}  # type: Dict[str, SourceClock]
        raw_clocks = raw.get('clocks', {})
        if not isinstance(raw_clocks, dict):
            raise ValueError(f'clocks for {what} is not a dictionary')
        for clk_name, src_name in raw_clocks.items():
            src = sources.get(src_name)
            if src is None:
                raise ValueError(f'The {clk_name} entry of clocks for {what} '
                                 f'has source {src_name}, which is not a '
                                 f'known clock source.')
            self.clocks[clk_name] = src

    def add_clock(self, clk_name: str, src: SourceClock):
        # Duplicates are ok, so long as they have the same source.
        existing_src = self.clocks.get(clk_name)
        if existing_src is not None:
            if existing_src is not src:
                raise ValueError(f'Cannot add clock {clk_name} to group '
                                 f'{self.name} with source {src.name}: the '
                                 f'clock is there already with source '
                                 f'{existing_src.name}.')
        else:
            self.clocks[clk_name] = src

    def _asdict(self) -> Dict[str, object]:
        return {
            'name': self.name,
            'src': self.src,
            'sw_cg': self.sw_cg,
            'unique': _bool_to_yn(self.unique),
            'clocks': {name: src.name for name, src in self.clocks.items()}
        }


class Clocks:
    '''Clock connections for the chip'''
    def __init__(self, raw: Dict[str, object]):
        self.hier_paths = {}
        assert isinstance(raw['hier_paths'], dict)
        for grp_src, path in raw['hier_paths'].items():
            self.hier_paths[str(grp_src)] = str(path)

        assert isinstance(raw['srcs'], list)
        self.srcs = {}
        for r in raw['srcs']:
            clk = SourceClock(r)
            self.srcs[clk.name] = clk

        self.derived_srcs = {}
        for r in raw['derived_srcs']:
            clk = DerivedSourceClock(r, self.srcs)
            self.derived_srcs[clk.name] = clk

        self.all_srcs = self.srcs.copy()
        self.all_srcs.update(self.derived_srcs)

        self.groups = {}
        assert isinstance(raw['groups'], list)
        for idx, raw_grp in enumerate(raw['groups']):
            assert isinstance(raw_grp, dict)
            grp = Group(raw_grp, self.srcs, f'clocks.groups[{idx}]')
            self.groups[grp.name] = grp

    def _asdict(self) -> Dict[str, object]:
        return {
            'hier_paths': self.hier_paths,
            'srcs': list(self.srcs.values()),
            'derived_srcs': list(self.derived_srcs.values()),
            'groups': list(self.groups.values())
        }

    def add_clock_to_group(self, grp: Group, clk_name: str, src_name: str):
        src = self.all_srcs.get(src_name)
        if src is None:
            raise ValueError(f'Cannot add clock {clk_name} to group '
                             f'{grp.name}: the given source name is '
                             f'{src_name}, which is unknown.')
        grp.add_clock(clk_name, src)

    def get_clock_by_name(self, name: str) -> object:

        ret = self.all_srcs.get(name)
        if ret is None:
            raise ValueError(f'{name} is not a valid clock')
        return ret