from typing import Any, Generator, Iterable, TextIO

import struct
import sys

from phasm.codestyle import phasm_render
from phasm.type3 import types as type3types
from phasm.runtime import calculate_alloc_size

from . import runners

DASHES = '-' * 16

class SuiteResult:
    def __init__(self) -> None:
        self.returned_value = None

RUNNER_CLASS_MAP = {
    'pywasm': runners.RunnerPywasm,
    'pywasm3': runners.RunnerPywasm3,
    'wasmtime': runners.RunnerWasmtime,
    'wasmer': runners.RunnerWasmer,
}

class Suite:
    """
    WebAssembly test suite
    """
    def __init__(self, code_py: str) -> None:
        self.code_py = code_py

    def run_code(self, *args: Any, runtime: str = 'pywasm3', func_name: str = 'testEntry', imports: runners.Imports = None) -> Any:
        """
        Compiles the given python code into wasm and
        then runs it

        Returned is an object with the results set
        """
        class_ = RUNNER_CLASS_MAP[runtime]

        runner = class_(self.code_py)

        runner.parse()
        runner.compile_ast()
        runner.compile_wat()
        runner.compile_wasm()
        runner.interpreter_setup()
        runner.interpreter_load(imports)

        write_header(sys.stderr, 'Phasm')
        runner.dump_phasm_code(sys.stderr)
        write_header(sys.stderr, 'Assembly')
        runner.dump_wasm_wat(sys.stderr)

        # Check if code formatting works
        assert self.code_py == '\n' + phasm_render(runner.phasm_ast) # \n for formatting in tests

        wasm_args = []
        if args:
            write_header(sys.stderr, 'Memory (pre alloc)')
            runner.interpreter_dump_memory(sys.stderr)

            for arg in args:
                if isinstance(arg, (int, float, )):
                    wasm_args.append(arg)
                    continue

                if isinstance(arg, bytes):
                    adr = runner.call('stdlib.types.__alloc_bytes__', len(arg))
                    sys.stderr.write(f'Allocation 0x{adr:08x} {repr(arg)}\n')

                    runner.interpreter_write_memory(adr + 4, arg)
                    wasm_args.append(adr)
                    continue

                raise NotImplementedError(arg)

        write_header(sys.stderr, 'Memory (pre run)')
        runner.interpreter_dump_memory(sys.stderr)

        result = SuiteResult()
        result.returned_value = runner.call(func_name, *wasm_args)

        result.returned_value = _load_memory_stored_returned_value(
            runner,
            func_name,
            result.returned_value,
        )

        write_header(sys.stderr, 'Memory (post run)')
        runner.interpreter_dump_memory(sys.stderr)

        return result

def write_header(textio: TextIO, msg: str) -> None:
    textio.write(f'{DASHES} {msg.ljust(16)}  {DASHES}\n')

def _load_memory_stored_returned_value(
        runner: runners.RunnerBase,
        func_name: str,
        wasm_value: Any,
    ) -> Any:
    ret_type3 = runner.phasm_ast.functions[func_name].returns_type3

    if ret_type3 is type3types.none:
        return None

    if ret_type3 in (type3types.i32, type3types.i64):
        assert isinstance(wasm_value, int), wasm_value
        return wasm_value

    if ret_type3 in (type3types.u8, type3types.u32, type3types.u64):
        assert isinstance(wasm_value, int), wasm_value
        assert 0 <= wasm_value, 'TODO: Extract negative values'
        return wasm_value

    if ret_type3 in (type3types.f32, type3types.f64, ):
        assert isinstance(wasm_value, float), wasm_value
        return wasm_value

    if ret_type3 is type3types.bytes:
        assert isinstance(wasm_value, int), wasm_value

        return _load_bytes_from_address(runner, ret_type3, wasm_value)

    if isinstance(ret_type3, type3types.AppliedType3):
        if ret_type3.base is type3types.static_array:
            assert isinstance(wasm_value, int), wasm_value

            return _load_static_array_from_address(runner, ret_type3, wasm_value)

        if ret_type3.base is type3types.tuple:
            assert isinstance(wasm_value, int), wasm_value

            return _load_tuple_from_address(runner, ret_type3, wasm_value)

    raise NotImplementedError(ret_type3, wasm_value)

def _unpack(runner: runners.RunnerBase, typ: type3types.Type3, inp: bytes) -> Any:
    if typ is type3types.u8:
        # See compiler.py, LOAD_STORE_TYPE_MAP and module_data_u8
        assert len(inp) == 4
        return struct.unpack('<I', inp)[0]

    if typ is type3types.u32:
        assert len(inp) == 4
        return struct.unpack('<I', inp)[0]

    if typ is type3types.u64:
        assert len(inp) == 8
        return struct.unpack('<Q', inp)[0]

    if typ is type3types.i8:
        # See compiler.py, LOAD_STORE_TYPE_MAP and module_data_i8
        assert len(inp) == 4
        return struct.unpack('<i', inp)[0]

    if typ is type3types.i32:
        assert len(inp) == 4
        return struct.unpack('<i', inp)[0]

    if typ is type3types.i64:
        assert len(inp) == 8
        return struct.unpack('<q', inp)[0]

    if typ is type3types.f32:
        assert len(inp) == 4
        return struct.unpack('<f', inp)[0]

    if typ is type3types.f64:
        assert len(inp) == 8
        return struct.unpack('<d', inp)[0]

    if typ is type3types.bytes:
        # Note: For applied types, inp should contain a 4 byte pointer
        assert len(inp) == 4
        adr = struct.unpack('<I', inp)[0]

        return _load_bytes_from_address(runner, typ, adr)

    if isinstance(typ, type3types.AppliedType3):
        # Note: For applied types, inp should contain a 4 byte pointer
        assert len(inp) == 4
        adr = struct.unpack('<I', inp)[0]

        if typ.base is type3types.static_array:
            return _load_static_array_from_address(runner, typ, adr)

        if typ.base is type3types.tuple:
            return _load_tuple_from_address(runner, typ, adr)

    raise NotImplementedError(typ, inp)

def _load_bytes_from_address(runner: runners.RunnerBase, typ: type3types.Type3, adr: int) -> bytes:
    sys.stderr.write(f'Reading 0x{adr:08x}\n')
    read_bytes = runner.interpreter_read_memory(adr, 4)
    bytes_len,  = struct.unpack('<I', read_bytes)

    adr += 4
    sys.stderr.write(f'Reading 0x{adr:08x}\n')
    return runner.interpreter_read_memory(adr, bytes_len)

def _split_read_bytes(all_bytes: bytes, split_sizes: Iterable[int]) -> Generator[bytes, None, None]:
    offset = 0
    for size in split_sizes:
        yield all_bytes[offset:offset + size]
        offset += size

def _load_static_array_from_address(runner: runners.RunnerBase, typ: type3types.AppliedType3, adr: int) -> Any:
    assert 2 == len(typ.args)
    sub_typ, len_typ = typ.args

    assert not isinstance(sub_typ, type3types.PlaceholderForType)
    assert isinstance(len_typ, type3types.IntType3)

    sa_len = len_typ.value

    arg_size_1 = calculate_alloc_size(sub_typ, is_member=True)
    arg_sizes = [arg_size_1 for _ in range(sa_len)] # _split_read_bytes requires one arg per value

    read_bytes = runner.interpreter_read_memory(adr, sum(arg_sizes))

    return tuple(
        _unpack(runner, sub_typ, arg_bytes)
        for arg_bytes in _split_read_bytes(read_bytes, arg_sizes)
    )

def _load_tuple_from_address(runner: runners.RunnerBase, typ: type3types.Type3, adr: int) -> Any:
    assert isinstance(typ, type3types.AppliedType3)
    assert typ.base is type3types.tuple

    typ_list = [
        x
        for x in typ.args
        if not isinstance(x, type3types.PlaceholderForType)
    ]
    assert len(typ_list) == len(typ.args)

    arg_sizes = [
        calculate_alloc_size(x, is_member=True)
        for x in typ_list
    ]

    read_bytes = runner.interpreter_read_memory(adr, sum(arg_sizes))

    return tuple(
        _unpack(runner, arg_typ, arg_bytes)
        for arg_typ, arg_bytes in zip(typ_list, _split_read_bytes(read_bytes, arg_sizes))
    )