import re
from function_puller import (
    get_spec,
    SpecObject,
)
from argparse import ArgumentParser
from typing import (
    Dict,
    List,
    Optional,
)


PHASE0_IMPORTS = '''from math import log2
from typing import (
    Any, Callable, Dict, Set, Sequence, Tuple,
)

from dataclasses import (
    dataclass,
    field,
)

from eth2spec.utils.ssz.ssz_impl import (
    hash_tree_root,
    signing_root,
)
from eth2spec.utils.ssz.ssz_typing import (
    Bit, Bool, Container, List, Vector, Bytes, uint64,
    Bytes4, Bytes32, Bytes48, Bytes96,
)
from eth2spec.utils.bls import (
    bls_aggregate_pubkeys,
    bls_verify,
    bls_verify_multiple,
)

from eth2spec.utils.hash_function import hash
'''
PHASE1_IMPORTS = '''from math import log2
from typing import (
    Any, Callable, Dict, Optional, Set, Sequence, MutableSequence, Tuple,
)

from dataclasses import (
    dataclass,
    field,
)

from eth2spec.utils.ssz.ssz_impl import (
    hash_tree_root,
    signing_root,
    serialize,
    is_empty,
)
from eth2spec.utils.ssz.ssz_typing import (
    Bit, Bool, Container, List, Vector, Bytes, uint64,
    Bytes4, Bytes32, Bytes48, Bytes96,
)
from eth2spec.utils.bls import (
    bls_aggregate_pubkeys,
    bls_verify,
    bls_verify_multiple,
)

from eth2spec.utils.hash_function import hash
'''
SUNDRY_FUNCTIONS = '''
# Monkey patch hash cache
_hash = hash
hash_cache: Dict[bytes, Hash] = {}


def hash(x: bytes) -> Hash:
    if x not in hash_cache:
        hash_cache[x] = Hash(_hash(x))
    return hash_cache[x]


# Monkey patch validator compute committee code
_compute_committee = compute_committee
committee_cache: Dict[Tuple[Hash, Hash, int, int], Sequence[ValidatorIndex]] = {}


def compute_committee(indices: Sequence[ValidatorIndex],  # type: ignore
                      seed: Hash,
                      index: int,
                      count: int) -> Sequence[ValidatorIndex]:
    param_hash = (hash(b''.join(index.to_bytes(length=4, byteorder='little') for index in indices)), seed, index, count)

    if param_hash not in committee_cache:
        committee_cache[param_hash] = _compute_committee(indices, seed, index, count)
    return committee_cache[param_hash]


# Access to overwrite spec constants based on configuration
def apply_constants_preset(preset: Dict[str, Any]) -> None:
    global_vars = globals()
    for k, v in preset.items():
        global_vars[k] = v

    # Deal with derived constants
    global_vars['GENESIS_EPOCH'] = slot_to_epoch(GENESIS_SLOT)

    # Initialize SSZ types again, to account for changed lengths
    init_SSZ_types()
'''


def strip_comments(raw: str) -> str:
    comment_line_regex = re.compile('^\s+# ')
    lines = raw.split('\n')
    out = []
    for line in lines:
        if not comment_line_regex.match(line):
            if '  #' in line:
                line = line[:line.index('  #')]
            out.append(line)
    return '\n'.join(out)


def objects_to_spec(functions: Dict[str, str],
                    custom_types: Dict[str, str],
                    constants: Dict[str, str],
                    ssz_objects: Dict[str, str],
                    inserts: Dict[str, str],
                    imports: Dict[str, str],
                    ) -> str:
    """
    Given all the objects that constitute a spec, combine them into a single pyfile.
    """
    new_type_definitions = (
        '\n\n'.join(
            [
                f"class {key}({value}):\n    pass\n"
                for key, value in custom_types.items()
            ]
        )
    )
    functions_spec = '\n\n'.join(functions.values())
    constants_spec = '\n'.join(map(lambda x: '%s = %s' % (x, constants[x]), constants))
    ssz_objects_instantiation_spec = '\n\n'.join(ssz_objects.values())
    ssz_objects_reinitialization_spec = (
        'def init_SSZ_types() -> None:\n    global_vars = globals()\n\n    '
        + '\n\n    '.join([strip_comments(re.sub(r'(?!\n\n)\n', r'\n    ', value[:-1]))
                           for value in ssz_objects.values()])
        + '\n\n'
        + '\n'.join(map(lambda x: '    global_vars[\'%s\'] = %s' % (x, x), ssz_objects.keys()))
    )
    spec = (
        imports
        + '\n\n' + new_type_definitions
        + '\n\n' + constants_spec
        + '\n\n\n' + ssz_objects_instantiation_spec
        + '\n\n' + functions_spec
        + '\n' + SUNDRY_FUNCTIONS
        + '\n\n' + ssz_objects_reinitialization_spec
        + '\n'
    )
    # Handle @inserts
    for key, value in inserts.items():
        spec = re.sub('[ ]*# %s\\n' % key, value, spec)
    return spec


def combine_functions(old_functions: Dict[str, str], new_functions: Dict[str, str]) -> Dict[str, str]:
    for key, value in new_functions.items():
        old_functions[key] = value
    return old_functions


def combine_constants(old_constants: Dict[str, str], new_constants: Dict[str, str]) -> Dict[str, str]:
    for key, value in new_constants.items():
        old_constants[key] = value
    return old_constants


ignored_dependencies = [
    'Bit', 'Bool', 'Vector', 'List', 'Container', 'Hash', 'BLSPubkey', 'BLSSignature', 'Bytes', 'BytesN'
    'Bytes4', 'Bytes32', 'Bytes48', 'Bytes96',
    'uint8', 'uint16', 'uint32', 'uint64', 'uint128', 'uint256',
    'bytes'  # to be removed after updating spec doc
]


def dependency_order_ssz_objects(objects: Dict[str, str], custom_types: Dict[str, str]) -> None:
    """
    Determines which SSZ Object is depenedent on which other and orders them appropriately
    """
    items = list(objects.items())
    for key, value in items:
        dependencies = []
        for line in value.split('\n'):
            if not re.match(r'\s+\w+: .+', line):
                continue  # skip whitespace etc.
            line = line[line.index(':') + 1:]  # strip of field name
            if '#' in line:
                line = line[:line.index('#')]  # strip of comment
            dependencies.extend(re.findall(r'(\w+)', line))  # catch all legible words, potential dependencies
        dependencies = filter(lambda x: '_' not in x and x.upper() != x, dependencies)  # filter out constants
        dependencies = filter(lambda x: x not in ignored_dependencies, dependencies)
        dependencies = filter(lambda x: x not in custom_types, dependencies)
        for dep in dependencies:
            key_list = list(objects.keys())
            for item in [dep, key] + key_list[key_list.index(dep)+1:]:
                objects[item] = objects.pop(item)


def combine_ssz_objects(old_objects: Dict[str, str], new_objects: Dict[str, str], custom_types) -> Dict[str, str]:
    """
    Takes in old spec and new spec ssz objects, combines them,
    and returns the newer versions of the objects in dependency order.
    """
    for key, value in new_objects.items():
        if key in old_objects:
            # remove trailing newline
            old_objects[key] = old_objects[key]
            # remove leading variable name
            value = re.sub(r'^class [\w]*\(Container\):\n', '', value)
        old_objects[key] = old_objects.get(key, '') + value
    dependency_order_ssz_objects(old_objects, custom_types)
    return old_objects


# inserts are handeled the same way as functions
combine_inserts = combine_functions


def combine_spec_objects(spec0: SpecObject, spec1: SpecObject) -> SpecObject:
    """
    Takes in two spec variants (as tuples of their objects) and combines them using the appropriate combiner function.
    """
    functions0, custom_types0, constants0, ssz_objects0, inserts0 = spec0
    functions1, custom_types1, constants1, ssz_objects1, inserts1 = spec1
    functions = combine_functions(functions0, functions1)
    custom_types = combine_constants(custom_types0, custom_types1)
    constants = combine_constants(constants0, constants1)
    ssz_objects = combine_ssz_objects(ssz_objects0, ssz_objects1, custom_types)
    inserts = combine_inserts(inserts0, inserts1)
    return functions, custom_types, constants, ssz_objects, inserts


def build_phase0_spec(phase0_sourcefile: str, fork_choice_sourcefile: str, outfile: str=None) -> Optional[str]:
    phase0_spec = get_spec(phase0_sourcefile)
    fork_choice_spec = get_spec(fork_choice_sourcefile)
    spec_objects = combine_spec_objects(phase0_spec, fork_choice_spec)
    spec = objects_to_spec(*spec_objects, PHASE0_IMPORTS)
    if outfile is not None:
        with open(outfile, 'w') as out:
            out.write(spec)
    return spec


def build_phase1_spec(phase0_sourcefile: str,
                      phase1_custody_sourcefile: str,
                      phase1_shard_sourcefile: str,
                      fork_choice_sourcefile: str,
                      outfile: str=None) -> Optional[str]:
    phase0_spec = get_spec(phase0_sourcefile)
    phase1_custody = get_spec(phase1_custody_sourcefile)
    phase1_shard_data = get_spec(phase1_shard_sourcefile)
    fork_choice_spec = get_spec(fork_choice_sourcefile)
    spec_objects = phase0_spec
    for value in [phase1_custody, phase1_shard_data, fork_choice_spec]:
        spec_objects = combine_spec_objects(spec_objects, value)
    spec = objects_to_spec(*spec_objects, PHASE1_IMPORTS)
    if outfile is not None:
        with open(outfile, 'w') as out:
            out.write(spec)
    return spec


if __name__ == '__main__':
    description = '''
Build the specs from the md docs.
If building phase 0:
    1st argument is input spec.md
    2nd argument is input fork_choice.md
    3rd argument is output spec.py

If building phase 1:
    1st argument is input spec_phase0.md
    2nd argument is input spec_phase1_custody.md
    3rd argument is input spec_phase1_shard_data.md
    4th argument is input fork_choice.md
    5th argument is output spec.py
'''
    parser = ArgumentParser(description=description)
    parser.add_argument("-p", "--phase", dest="phase", type=int, default=0, help="Build for phase #")
    parser.add_argument(dest="files", help="Input and output files", nargs="+")

    args = parser.parse_args()
    if args.phase == 0:
        if len(args.files) == 3:
            build_phase0_spec(*args.files)
        else:
            print(" Phase 0 requires an output as well as spec and forkchoice files.")
    elif args.phase == 1:
        if len(args.files) == 5:
            build_phase1_spec(*args.files)
        else:
            print(" Phase 1 requires an output as well as 4 input files (phase0.md and phase1.md, phase1.md, fork_choice.md)")
    else:
        print("Invalid phase: {0}".format(args.phase))