// Copyright 2021-2026 Vector 35 Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use crate::dwarfdebuginfo::{DebugInfoBuilder, DebugInfoBuilderContext, TypeUID};
use crate::types::get_type;
use crate::{helpers::*, ReaderType};

use binaryninja::{
    rc::*,
    types::{EnumerationBuilder, FunctionParameter, ReferenceType, Type, TypeBuilder},
};

use gimli::Dwarf;
use gimli::{constants, AttributeValue::Encoding, DebuggingInformationEntry, Unit};

pub(crate) fn handle_base_type<R: ReaderType>(
    dwarf: &Dwarf<R>,
    unit: &Unit<R>,
    entry: &DebuggingInformationEntry<R>,
    debug_info_builder_context: &DebugInfoBuilderContext<R>,
) -> Option<Ref<Type>> {
    // All base types have:
    //   DW_AT_encoding (our concept of type_class)
    //   DW_AT_byte_size and/or DW_AT_bit_size
    //   *DW_AT_name
    //   *DW_AT_endianity (assumed default for arch)
    //   *DW_AT_data_bit_offset (assumed 0)
    //   *Some indication of signedness?
    //   * = Optional

    let name = debug_info_builder_context.get_name(dwarf, unit, entry)?;
    let size = get_size_as_usize(entry)?;
    match entry.attr_value(constants::DW_AT_encoding) {
        Ok(Some(Encoding(encoding))) => {
            match encoding {
                constants::DW_ATE_address => None,
                constants::DW_ATE_boolean => Some(Type::bool()),
                constants::DW_ATE_complex_float => None,
                constants::DW_ATE_float => Some(Type::named_float(size, &name)),
                constants::DW_ATE_signed => Some(Type::named_int(size, true, &name)),
                constants::DW_ATE_signed_char => Some(Type::named_int(size, true, &name)),
                constants::DW_ATE_unsigned => Some(Type::named_int(size, false, &name)),
                constants::DW_ATE_unsigned_char => Some(Type::named_int(size, false, &name)),
                constants::DW_ATE_imaginary_float => None,
                constants::DW_ATE_packed_decimal => None,
                constants::DW_ATE_numeric_string => None,
                constants::DW_ATE_edited => None,
                constants::DW_ATE_signed_fixed => None,
                constants::DW_ATE_unsigned_fixed => None,
                constants::DW_ATE_decimal_float => Some(Type::named_float(size, &name)),
                constants::DW_ATE_UTF => Some(Type::named_int(size, false, &name)), // TODO : Verify
                constants::DW_ATE_UCS => None,
                constants::DW_ATE_ASCII => None, // Some sort of array?
                constants::DW_ATE_lo_user => None,
                constants::DW_ATE_hi_user => None,
                _ => None, // Anything else is invalid at time of writing (gimli v0.23.0)
            }
        }
        _ => None,
    }
}

pub(crate) fn handle_enum<R: ReaderType>(
    dwarf: &Dwarf<R>,
    unit: &Unit<R>,
    entry: &DebuggingInformationEntry<R>,
    debug_info_builder_context: &DebugInfoBuilderContext<R>,
) -> Option<Ref<Type>> {
    // All base types have:
    //   DW_AT_byte_size
    //   *DW_AT_name
    //   *DW_AT_enum_class
    //   *DW_AT_type
    //   ?DW_AT_abstract_origin
    //   ?DW_AT_accessibility
    //   ?DW_AT_allocated
    //   ?DW_AT_associated
    //   ?DW_AT_bit_size
    //   ?DW_AT_bit_stride
    //   ?DW_AT_byte_stride
    //   ?DW_AT_data_location
    //   ?DW_AT_declaration
    //   ?DW_AT_description
    //   ?DW_AT_sibling
    //   ?DW_AT_signature
    //   ?DW_AT_specification
    //   ?DW_AT_start_scope
    //   ?DW_AT_visibility
    //   * = Optional

    // Children of enumeration_types are enumerators which contain:
    //  DW_AT_name
    //  DW_AT_const_value
    //  *DW_AT_description

    let mut enumeration_builder = EnumerationBuilder::new();

    let mut tree = match unit.entries_tree(Some(entry.offset())) {
        Ok(x) => x,
        Err(e) => {
            tracing::error!("Failed to get enum entry tree: {}", e);
            return None;
        }
    };

    let tree_root = match tree.root() {
        Ok(x) => x,
        Err(e) => {
            tracing::error!("Failed to get enum entry tree root: {}", e);
            return None;
        }
    };

    let mut children = tree_root.children();
    while let Ok(Some(child)) = children.next() {
        if child.entry().tag() == constants::DW_TAG_enumerator {
            let name = debug_info_builder_context.get_name(dwarf, unit, child.entry())?;
            match &child.entry().attr(constants::DW_AT_const_value) {
                Ok(Some(attr)) => {
                    if let Some(value) = get_attr_as_u64(attr) {
                        enumeration_builder.insert(&name, value);
                    } else {
                        // Somehow the child entry is not a const value.
                        tracing::error!("Unhandled enum member value type for `{}`", name);
                    }
                }
                Ok(None) => {
                    // Somehow the child entry does not have a const value.
                    tracing::error!("Enum member `{}` has no constant value attribute", name);
                }
                Err(e) => {
                    tracing::error!("Error parsing next attribute entry for `{}`: {}", name, e);
                    return None;
                }
            }
        }
    }

    let width = match get_size_as_usize(entry).unwrap_or(8) {
        0 => debug_info_builder_context.default_address_size(),
        x => x,
    };

    Some(Type::enumeration(
        &enumeration_builder.finalize(),
        // TODO: This looks bad, look at the comment in [`Type::width`].
        width.try_into().expect("Enum cannot be zero width"),
        false,
    ))
}

pub(crate) fn handle_typedef(
    debug_info_builder: &mut DebugInfoBuilder,
    entry_type: Option<TypeUID>,
    typedef_name: &str,
) -> (Option<Ref<Type>>, bool) {
    // All base types have:
    //   DW_AT_name
    //   *DW_AT_type
    //   * = Optional

    // This will fail in the case where we have a typedef to a type that doesn't exist (failed to parse, incomplete, etc)
    if let Some(entry_type_offset) = entry_type {
        if let Some(t) = debug_info_builder.get_type(entry_type_offset) {
            let typedef_type = Type::named_type_from_type(typedef_name, &t.get_type());
            return (Some(typedef_type), typedef_name != t.name);
        }
    }

    // 5.3: "typedef represents a declaration of the type that is not also a definition"
    (None, false)
}

pub(crate) fn handle_pointer<R: ReaderType>(
    entry: &DebuggingInformationEntry<R>,
    debug_info_builder_context: &DebugInfoBuilderContext<R>,
    debug_info_builder: &mut DebugInfoBuilder,
    entry_type: Option<TypeUID>,
    reference_type: ReferenceType,
) -> Option<Ref<Type>> {
    // All pointer types have:
    //   DW_AT_type
    //   *DW_AT_byte_size
    //   ?DW_AT_name
    //   ?DW_AT_address
    //   ?DW_AT_allocated
    //   ?DW_AT_associated
    //   ?DW_AT_data_location
    //   * = Optional

    let pointer_size = match get_size_as_usize(entry) {
        Some(x) => x,
        None => debug_info_builder_context.default_address_size(),
    };

    let target_type = match entry_type {
        Some(entry_type_offset) => {
            let debug_target_type =
                debug_info_builder.get_type(entry_type_offset).or_else(|| {
                    tracing::error!(
                        "Failed to get pointer target type at entry offset {}",
                        entry_type_offset
                    );
                    None
                })?;

            debug_target_type.get_type()
        }
        None => Type::void(),
    };

    Some(Type::pointer_of_width(
        target_type.as_ref(),
        pointer_size,
        false,
        false,
        Some(reference_type),
    ))
}

pub(crate) fn handle_array<R: ReaderType>(
    unit: &Unit<R>,
    entry: &DebuggingInformationEntry<R>,
    debug_info_builder: &mut DebugInfoBuilder,
    entry_type: Option<TypeUID>,
) -> Option<Ref<Type>> {
    // All array types have:
    //    DW_AT_type
    //   *DW_AT_name
    //   *DW_AT_ordering
    //   *DW_AT_byte_stride or DW_AT_bit_stride
    //   *DW_AT_byte_size or DW_AT_bit_size
    //   *DW_AT_allocated
    //   *DW_AT_associated and
    //   *DW_AT_data_location
    //   * = Optional
    //   For multidimensional arrays, DW_TAG_subrange_type or DW_TAG_enumeration_type

    let entry_type_offset = entry_type?;
    let parent_type = debug_info_builder
        .get_type(entry_type_offset)
        .or_else(|| {
            tracing::error!(
                "Failed to get array member type at entry offset {}",
                entry_type_offset
            );
            None
        })?
        .get_type();

    let mut tree = match unit.entries_tree(Some(entry.offset())) {
        Ok(x) => x,
        Err(e) => {
            tracing::error!("Failed to get array entry tree: {}", e);
            return None;
        }
    };
    let tree_root = match tree.root() {
        Ok(x) => x,
        Err(e) => {
            tracing::error!("Failed to get array entry tree root: {}", e);
            return None;
        }
    };
    let mut children = tree_root.children();

    // TODO : This is currently applying the size in reverse order
    let mut result_type: Option<Ref<Type>> = None;
    while let Ok(Some(child)) = children.next() {
        if let Some(inner_type) = result_type {
            result_type = Some(Type::array(
                inner_type.as_ref(),
                get_subrange_size(child.entry()),
            ));
        } else {
            result_type = Some(Type::array(
                parent_type.as_ref(),
                get_subrange_size(child.entry()),
            ));
        }
    }

    result_type.map_or(Some(Type::array(parent_type.as_ref(), 0)), Some)
}

pub(crate) fn handle_function<R: ReaderType>(
    dwarf: &Dwarf<R>,
    unit: &Unit<R>,
    entry: &DebuggingInformationEntry<R>,
    debug_info_builder_context: &DebugInfoBuilderContext<R>,
    debug_info_builder: &mut DebugInfoBuilder,
    entry_type: Option<TypeUID>,
) -> Option<Ref<Type>> {
    // All subroutine types have:
    //   *DW_AT_name
    //   *DW_AT_type (if not provided, void)
    //   *DW_AT_prototyped
    //   ?DW_AT_abstract_origin
    //   ?DW_AT_accessibility
    //   ?DW_AT_address_class
    //   ?DW_AT_allocated
    //   ?DW_AT_associated
    //   ?DW_AT_data_location
    //   ?DW_AT_declaration
    //   ?DW_AT_description
    //   ?DW_AT_sibling
    //   ?DW_AT_start_scope
    //   ?DW_AT_visibility
    //   * = Optional

    // May have children, including DW_TAG_formal_parameters, which all have:
    //   *DW_AT_type
    //   * = Optional
    // or is otherwise DW_TAG_unspecified_parameters

    let return_type = match entry_type {
        Some(entry_type_offset) => debug_info_builder
            .get_type(entry_type_offset)
            .expect("Subroutine return type was not processed")
            .get_type(),
        None => Type::void(),
    };

    // Alias function type in the case that it contains itself
    let name = debug_info_builder_context
        .get_name(dwarf, unit, entry)
        .unwrap_or("_unnamed_func".to_string());
    let ntr =
        Type::named_type_from_type(&name, &Type::function(return_type.as_ref(), vec![], false));
    debug_info_builder.add_type(get_uid(dwarf, unit, entry), name, ntr, false, None);

    let mut parameters: Vec<FunctionParameter> = vec![];
    let mut variable_arguments = false;

    // Get all the children and populate
    let mut tree = match unit.entries_tree(Some(entry.offset())) {
        Ok(x) => x,
        Err(e) => {
            tracing::error!("Failed to get function entry tree: {}", e);
            return None;
        }
    };

    let tree_root = match tree.root() {
        Ok(x) => x,
        Err(e) => {
            tracing::error!("Failed to get function entry tree root: {}", e);
            return None;
        }
    };

    let mut children = tree_root.children();
    while let Ok(Some(child)) = children.next() {
        if child.entry().tag() == constants::DW_TAG_formal_parameter {
            let Some(child_uid) = get_type(
                dwarf,
                unit,
                child.entry(),
                debug_info_builder_context,
                debug_info_builder,
            ) else {
                tracing::error!(
                    "Failed to get function parameter child type in unit {:?} at offset {:x}",
                    unit.header.offset(),
                    child.entry().offset().0,
                );
                continue;
            };
            let name = debug_info_builder_context.get_name(dwarf, unit, child.entry());

            let child_debug_type = debug_info_builder.get_type(child_uid).or_else(|| {
                tracing::error!(
                    "Failed to get function parameter type with uid {}",
                    child_uid
                );
                None
            })?;
            let child_type = child_debug_type.get_type();

            parameters.push(FunctionParameter::new(
                child_type,
                name.unwrap_or_default(),
                None,
            ));
        } else if child.entry().tag() == constants::DW_TAG_unspecified_parameters {
            variable_arguments = true;
        }
    }

    // Remove the aliased type from the builder.
    debug_info_builder.remove_type(get_uid(dwarf, unit, entry));

    Some(Type::function(
        return_type.as_ref(),
        parameters,
        variable_arguments,
    ))
}

pub(crate) fn handle_const(
    debug_info_builder: &mut DebugInfoBuilder,
    entry_type: Option<TypeUID>,
) -> Option<Ref<Type>> {
    // All const types have:
    //   ?DW_AT_allocated
    //   ?DW_AT_associated
    //   ?DW_AT_data_location
    //   ?DW_AT_name
    //   ?DW_AT_sibling
    //   ?DW_AT_type

    let target_type_builder = match entry_type {
        Some(entry_type_offset) => debug_info_builder
            .get_type(entry_type_offset)
            .or_else(|| {
                tracing::error!(
                    "Failed to get const type with entry offset {}",
                    entry_type_offset
                );
                None
            })?
            .get_type()
            .to_builder(),
        None => TypeBuilder::void(),
    };

    Some(target_type_builder.set_const(true).finalize())
}

pub(crate) fn handle_volatile(
    debug_info_builder: &mut DebugInfoBuilder,
    entry_type: Option<TypeUID>,
) -> Option<Ref<Type>> {
    // All const types have:
    //   ?DW_AT_allocated
    //   ?DW_AT_associated
    //   ?DW_AT_data_location
    //   ?DW_AT_name
    //   ?DW_AT_sibling
    //   ?DW_AT_type

    let target_type_builder = match entry_type {
        Some(entry_type_offset) => debug_info_builder
            .get_type(entry_type_offset)
            .or_else(|| {
                tracing::error!(
                    "Failed to get volatile type with entry offset {}",
                    entry_type_offset
                );
                None
            })?
            .get_type()
            .to_builder(),
        None => TypeBuilder::void(),
    };

    Some(target_type_builder.set_volatile(true).finalize())
}