import ast
import logging
import ctypes
from llvmlite import ir
from .local_symbol import LocalSymbol
from pythonbpf.helper import HelperHandlerRegistry
from pythonbpf.vmlinux_parser.dependency_node import Field
from .expr import VmlinuxHandlerRegistry
from pythonbpf.type_deducer import ctypes_to_ir
from pythonbpf.maps import BPFMapType

logger = logging.getLogger(__name__)


def create_targets_and_rvals(stmt):
    """Create lists of targets and right-hand values from an assignment statement."""
    if isinstance(stmt.targets[0], ast.Tuple):
        if not isinstance(stmt.value, ast.Tuple):
            logger.warning("Mismatched multi-target assignment, skipping allocation")
            return [], []
        targets, rvals = stmt.targets[0].elts, stmt.value.elts
        if len(targets) != len(rvals):
            logger.warning("length of LHS != length of RHS, skipping allocation")
            return [], []
        return targets, rvals
    return stmt.targets, [stmt.value]


def handle_assign_allocation(
    builder, stmt, local_sym_tab, map_sym_tab, structs_sym_tab
):
    """Handle memory allocation for assignment statements."""

    logger.info(f"Handling assignment for allocation: {ast.dump(stmt)}")

    # NOTE: Support multi-target assignments (e.g.: a, b = 1, 2)
    targets, rvals = create_targets_and_rvals(stmt)

    for target, rval in zip(targets, rvals):
        # Skip non-name targets (e.g., struct field assignments)
        if isinstance(target, ast.Attribute):
            logger.debug(
                f"Struct field assignment to {target.attr}, no allocation needed"
            )
            continue

        if not isinstance(target, ast.Name):
            logger.warning(
                f"Unsupported assignment target type: {type(target).__name__}"
            )
            continue

        var_name = target.id
        # Skip if already allocated
        if var_name in local_sym_tab:
            logger.debug(f"Variable {var_name} already allocated, skipping")
            continue

        # Determine type and allocate based on rval
        if isinstance(rval, ast.Call):
            _allocate_for_call(
                builder, var_name, rval, local_sym_tab, map_sym_tab, structs_sym_tab
            )
        elif isinstance(rval, ast.Constant):
            _allocate_for_constant(builder, var_name, rval, local_sym_tab)
        elif isinstance(rval, ast.BinOp):
            _allocate_for_binop(builder, var_name, local_sym_tab)
        elif isinstance(rval, ast.Name):
            # Variable-to-variable assignment (b = a)
            _allocate_for_name(builder, var_name, rval, local_sym_tab)
        elif isinstance(rval, ast.Attribute):
            # Struct field-to-variable assignment (a = dat.fld)
            _allocate_for_attribute(
                builder, var_name, rval, local_sym_tab, structs_sym_tab
            )
        else:
            logger.warning(
                f"Unsupported assignment value type for {var_name}: {type(rval).__name__}"
            )


def _allocate_for_call(
    builder, var_name, rval, local_sym_tab, map_sym_tab, structs_sym_tab
):
    """Allocate memory for variable assigned from a call."""

    if isinstance(rval.func, ast.Name):
        call_type = rval.func.id

        # C type constructors
        if call_type in ("c_int32", "c_int64", "c_uint32", "c_uint64", "c_void_p"):
            ir_type = ctypes_to_ir(call_type)
            var = builder.alloca(ir_type, name=var_name)
            var.align = ir_type.width // 8
            local_sym_tab[var_name] = LocalSymbol(var, ir_type)
            logger.info(f"Pre-allocated {var_name} as {call_type}")

        # Helper functions
        elif HelperHandlerRegistry.has_handler(call_type):
            ir_type = ir.IntType(64)  # Assume i64 return type
            var = builder.alloca(ir_type, name=var_name)
            var.align = 8
            local_sym_tab[var_name] = LocalSymbol(var, ir_type)
            logger.info(f"Pre-allocated {var_name} for helper {call_type}")

        # Deref function
        elif call_type == "deref":
            ir_type = ir.IntType(64)  # Assume i64 return type
            var = builder.alloca(ir_type, name=var_name)
            var.align = 8
            local_sym_tab[var_name] = LocalSymbol(var, ir_type)
            logger.info(f"Pre-allocated {var_name} for deref")

        # Struct constructors
        elif call_type in structs_sym_tab:
            struct_info = structs_sym_tab[call_type]
            if len(rval.args) == 0:
                # Zero-arg constructor: allocate the struct itself
                var = builder.alloca(struct_info.ir_type, name=var_name)
                local_sym_tab[var_name] = LocalSymbol(
                    var, struct_info.ir_type, call_type
                )
                logger.info(f"Pre-allocated {var_name} for struct {call_type}")
            else:
                # Pointer cast: allocate as pointer to struct
                ptr_type = ir.PointerType(struct_info.ir_type)
                var = builder.alloca(ptr_type, name=var_name)
                var.align = 8
                local_sym_tab[var_name] = LocalSymbol(var, ptr_type, call_type)
                logger.info(
                    f"Pre-allocated {var_name} for struct pointer cast to {call_type}"
                )

        elif VmlinuxHandlerRegistry.is_vmlinux_struct(call_type):
            # When calling struct_name(pointer), we're doing a cast, not construction
            # So we allocate as a pointer (i64) not as the actual struct
            var = builder.alloca(ir.IntType(64), name=var_name)
            var.align = 8
            local_sym_tab[var_name] = LocalSymbol(
                var, ir.IntType(64), VmlinuxHandlerRegistry.get_struct_type(call_type)
            )
            logger.info(
                f"Pre-allocated {var_name} for vmlinux struct pointer cast to {call_type}"
            )

        else:
            logger.warning(f"Unknown call type for allocation: {call_type}")

    elif isinstance(rval.func, ast.Attribute):
        # Map method calls - need double allocation for ptr handling
        _allocate_for_map_method(
            builder, var_name, rval, local_sym_tab, map_sym_tab, structs_sym_tab
        )

    else:
        logger.warning(f"Unsupported call function type for {var_name}")


def _allocate_for_map_method(
    builder, var_name, rval, local_sym_tab, map_sym_tab, structs_sym_tab
):
    """Allocate memory for variable assigned from map method (double alloc)."""

    map_name = rval.func.value.id
    method_name = rval.func.attr

    # NOTE: We will have to special case HashMap.lookup which returns a pointer to value type
    # The value type can be a struct as well, so we need to handle that properly
    # This special casing is not ideal, as over time other map methods may need similar handling
    # But for now, we will just handle lookup specifically
    if map_name not in map_sym_tab:
        logger.error(f"Map '{map_name}' not found for allocation")
        return

    if method_name != "lookup":
        # Fallback allocation for other map methods
        _allocate_for_map_method_fallback(builder, var_name, local_sym_tab)
        return

    map_params = map_sym_tab[map_name].params
    if map_params["type"] != BPFMapType.HASH:
        logger.warning(
            "Map method lookup used on non-hash map, using fallback allocation"
        )
        _allocate_for_map_method_fallback(builder, var_name, local_sym_tab)
        return

    value_type = map_params["value"]
    # Determine IR type for value
    if isinstance(value_type, str) and value_type in structs_sym_tab:
        struct_info = structs_sym_tab[value_type]
        value_ir_type = struct_info.ir_type
    else:
        value_ir_type = ctypes_to_ir(value_type)

    if value_ir_type is None:
        logger.warning(
            f"Could not determine IR type for map value '{value_type}', using fallback allocation"
        )
        _allocate_for_map_method_fallback(builder, var_name, local_sym_tab)
        return

    # Main variable (pointer to pointer)
    ir_type = ir.PointerType(ir.IntType(64))
    var = builder.alloca(ir_type, name=var_name)
    local_sym_tab[var_name] = LocalSymbol(var, ir_type, value_type)
    # Temporary variable for computed values
    tmp_ir_type = value_ir_type
    var_tmp = builder.alloca(tmp_ir_type, name=f"{var_name}_tmp")
    local_sym_tab[f"{var_name}_tmp"] = LocalSymbol(var_tmp, tmp_ir_type)
    logger.info(
        f"Pre-allocated {var_name} and {var_name}_tmp for map method lookup of type {value_ir_type}"
    )


def _allocate_for_map_method_fallback(builder, var_name, local_sym_tab):
    """Fallback allocation for map method variable (i64* and i64**)."""

    # Main variable (pointer to pointer)
    ir_type = ir.PointerType(ir.IntType(64))
    var = builder.alloca(ir_type, name=var_name)
    local_sym_tab[var_name] = LocalSymbol(var, ir_type)

    # Temporary variable for computed values
    tmp_ir_type = ir.IntType(64)
    var_tmp = builder.alloca(tmp_ir_type, name=f"{var_name}_tmp")
    local_sym_tab[f"{var_name}_tmp"] = LocalSymbol(var_tmp, tmp_ir_type)

    logger.info(
        f"Pre-allocated {var_name} and {var_name}_tmp for map method (fallback)"
    )


def _allocate_for_constant(builder, var_name, rval, local_sym_tab):
    """Allocate memory for variable assigned from a constant."""

    if isinstance(rval.value, bool):
        ir_type = ir.IntType(1)
        var = builder.alloca(ir_type, name=var_name)
        var.align = 1
        local_sym_tab[var_name] = LocalSymbol(var, ir_type)
        logger.info(f"Pre-allocated {var_name} as bool")

    elif isinstance(rval.value, int):
        ir_type = ir.IntType(64)
        var = builder.alloca(ir_type, name=var_name)
        var.align = 8
        local_sym_tab[var_name] = LocalSymbol(var, ir_type)
        logger.info(f"Pre-allocated {var_name} as i64")

    elif isinstance(rval.value, str):
        ir_type = ir.PointerType(ir.IntType(8))
        var = builder.alloca(ir_type, name=var_name)
        var.align = 8
        local_sym_tab[var_name] = LocalSymbol(var, ir_type)
        logger.info(f"Pre-allocated {var_name} as string")

    else:
        logger.warning(
            f"Unsupported constant type for {var_name}: {type(rval.value).__name__}"
        )


def _allocate_for_binop(builder, var_name, local_sym_tab):
    """Allocate memory for variable assigned from a binary operation."""
    ir_type = ir.IntType(64)  # Assume i64 result
    var = builder.alloca(ir_type, name=var_name)
    var.align = 8
    local_sym_tab[var_name] = LocalSymbol(var, ir_type)
    logger.info(f"Pre-allocated {var_name} for binop result")


def _get_type_name(ir_type):
    """Get a string representation of an IR type."""
    if isinstance(ir_type, ir.IntType):
        return f"i{ir_type.width}"
    elif isinstance(ir_type, ir.PointerType):
        return "ptr"
    elif isinstance(ir_type, ir.ArrayType):
        return f"[{ir_type.count}x{_get_type_name(ir_type.element)}]"
    else:
        return str(ir_type).replace(" ", "")


def allocate_temp_pool(builder, max_temps, local_sym_tab):
    """Allocate the temporary scratch space pool for helper arguments."""
    if not max_temps:
        logger.info("No temp pool allocation needed")
        return

    for tmp_type, cnt in max_temps.items():
        type_name = _get_type_name(tmp_type)
        logger.info(f"Allocating temp pool of {cnt} variables of type {type_name}")
        for i in range(cnt):
            temp_name = f"__helper_temp_{type_name}_{i}"
            temp_var = builder.alloca(tmp_type, name=temp_name)
            temp_var.align = _get_alignment(tmp_type)
            local_sym_tab[temp_name] = LocalSymbol(temp_var, tmp_type)
            logger.debug(f"Allocated temp variable: {temp_name}")


def _allocate_for_name(builder, var_name, rval, local_sym_tab):
    """Allocate memory for variable-to-variable assignment (b = a)."""
    source_var = rval.id

    if source_var not in local_sym_tab:
        logger.error(f"Source variable '{source_var}' not found in symbol table")
        return

    # Get type and metadata from source variable
    source_symbol = local_sym_tab[source_var]

    # Allocate with same type and alignment
    var = _allocate_with_type(builder, var_name, source_symbol.ir_type)
    local_sym_tab[var_name] = LocalSymbol(
        var, source_symbol.ir_type, source_symbol.metadata
    )

    logger.info(
        f"Pre-allocated {var_name} from {source_var} with type {source_symbol.ir_type}"
    )


def _allocate_for_attribute(builder, var_name, rval, local_sym_tab, structs_sym_tab):
    """Allocate memory for struct field-to-variable assignment (a = dat.fld)."""
    if not isinstance(rval.value, ast.Name):
        logger.warning(f"Complex attribute access not supported for {var_name}")
        return

    struct_var = rval.value.id
    field_name = rval.attr

    # Validate struct and field
    if struct_var not in local_sym_tab:
        logger.error(f"Struct variable '{struct_var}' not found")
        return

    struct_type: type = local_sym_tab[struct_var].metadata
    if not struct_type or struct_type not in structs_sym_tab:
        if VmlinuxHandlerRegistry.is_vmlinux_struct(struct_type.__name__):
            # Handle vmlinux struct field access
            vmlinux_struct_name = struct_type.__name__
            if not VmlinuxHandlerRegistry.has_field(vmlinux_struct_name, field_name):
                logger.error(
                    f"Field '{field_name}' not found in vmlinux struct '{vmlinux_struct_name}'"
                )
                return

            field_type: tuple[ir.GlobalVariable, Field] = (
                VmlinuxHandlerRegistry.get_field_type(vmlinux_struct_name, field_name)
            )
            field_ir, field = field_type

            # Determine the actual IR type based on the field's type
            actual_ir_type = None

            # Check if it's a ctypes primitive
            if field.type.__module__ == ctypes.__name__:
                try:
                    field_size_bytes = ctypes.sizeof(field.type)
                    field_size_bits = field_size_bytes * 8

                    if field_size_bits in [8, 16, 32, 64]:
                        # Special case: struct_xdp_md i32 fields should allocate as i64
                        # because load_ctx_field will zero-extend them to i64
                        if (
                            vmlinux_struct_name == "struct_xdp_md"
                            and field_size_bits == 32
                        ):
                            actual_ir_type = ir.IntType(64)
                            logger.info(
                                f"Allocating {var_name} as i64 for i32 field from struct_xdp_md.{field_name} "
                                "(will be zero-extended during load)"
                            )
                        else:
                            actual_ir_type = ir.IntType(field_size_bits)
                    else:
                        logger.warning(
                            f"Unusual field size {field_size_bits} bits for {field_name}"
                        )
                        actual_ir_type = ir.IntType(64)
                except Exception as e:
                    logger.warning(
                        f"Could not determine size for ctypes field {field_name}: {e}"
                    )
                    actual_ir_type = ir.IntType(64)
                    field_size_bits = 64

            # Check if it's a nested vmlinux struct or complex type
            elif field.type.__module__ == "vmlinux":
                # For pointers to structs, use pointer type (64-bit)
                if field.ctype_complex_type is not None and issubclass(
                    field.ctype_complex_type, ctypes._Pointer
                ):
                    actual_ir_type = ir.IntType(64)  # Pointer is always 64-bit
                    field_size_bits = 64
                # For embedded structs, this is more complex - might need different handling
                else:
                    logger.warning(
                        f"Field {field_name} is a nested vmlinux struct, using i64 for now"
                    )
                    actual_ir_type = ir.IntType(64)
                    field_size_bits = 64
            else:
                logger.warning(
                    f"Unknown field type module {field.type.__module__} for {field_name}"
                )
                actual_ir_type = ir.IntType(64)
                field_size_bits = 64

            # Pre-allocate the tmp storage used by load_struct_field (so we don't alloca inside handler)
            tmp_name = f"{struct_var}_{field_name}_tmp"
            tmp_ir_type = ir.IntType(field_size_bits)
            tmp_var = builder.alloca(tmp_ir_type, name=tmp_name)
            tmp_var.align = tmp_ir_type.width // 8
            local_sym_tab[tmp_name] = LocalSymbol(tmp_var, tmp_ir_type)
            logger.info(
                f"Pre-allocated temp {tmp_name} (i{field_size_bits}) for vmlinux field read {vmlinux_struct_name}.{field_name}"
            )

            # Allocate with the actual IR type for the destination var
            var = _allocate_with_type(builder, var_name, actual_ir_type)
            local_sym_tab[var_name] = LocalSymbol(var, actual_ir_type, field)

            logger.info(
                f"Pre-allocated {var_name} as {actual_ir_type} from vmlinux struct {vmlinux_struct_name}.{field_name}"
            )
            return
        else:
            logger.error(f"Struct type '{struct_type}' not found")
        return

    struct_info = structs_sym_tab[struct_type]
    if field_name not in struct_info.fields:
        logger.error(f"Field '{field_name}' not found in struct '{struct_type}'")
        return

    # Get field type
    field_type = struct_info.field_type(field_name)

    # Special case: char array -> allocate as i8* pointer instead
    if (
        isinstance(field_type, ir.ArrayType)
        and isinstance(field_type.element, ir.IntType)
        and field_type.element.width == 8
    ):
        alloc_type = ir.PointerType(ir.IntType(8))
        logger.info(f"Allocating {var_name} as i8* (pointer to char array)")
    else:
        alloc_type = field_type

    var = _allocate_with_type(builder, var_name, alloc_type)
    local_sym_tab[var_name] = LocalSymbol(var, alloc_type)

    logger.info(
        f"Pre-allocated {var_name} from {struct_var}.{field_name} with type {alloc_type}"
    )


def _allocate_with_type(builder, var_name, ir_type):
    """Allocate variable with appropriate alignment for type."""
    var = builder.alloca(ir_type, name=var_name)
    var.align = _get_alignment(ir_type)
    return var


def _get_alignment(ir_type):
    """Get appropriate alignment for IR type."""
    if isinstance(ir_type, ir.IntType):
        return ir_type.width // 8
    elif isinstance(ir_type, ir.ArrayType) and isinstance(ir_type.element, ir.IntType):
        return ir_type.element.width // 8
    else:
        return 8  # Default: pointer size