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use std::sync::Arc;

use cairo_lang_defs::plugin::{
    DynGeneratedFileAuxData, MacroPlugin, PluginDiagnostic, PluginGeneratedFile, PluginResult,
};
use cairo_lang_semantic::plugin::{AsDynMacroPlugin, SemanticPlugin, TrivialPluginAuxData};
use cairo_lang_syntax::node::ast::AttributeList;
use cairo_lang_syntax::node::db::SyntaxGroup;
use cairo_lang_syntax::node::{ast, Terminal, TypedSyntaxNode};

#[derive(Debug)]
pub struct DerivePlugin {}

impl MacroPlugin for DerivePlugin {
    fn generate_code(&self, db: &dyn SyntaxGroup, item_ast: ast::Item) -> PluginResult {
        match item_ast {
            ast::Item::Struct(struct_ast) => {
                generate_derive_code_for_type(db, struct_ast.name(db), struct_ast.attributes(db))
            }
            ast::Item::Enum(enum_ast) => {
                generate_derive_code_for_type(db, enum_ast.name(db), enum_ast.attributes(db))
            }
            ast::Item::ExternType(extern_type_ast) => generate_derive_code_for_type(
                db,
                extern_type_ast.name(db),
                extern_type_ast.attributes(db),
            ),
            _ => PluginResult::default(),
        }
    }
}
impl AsDynMacroPlugin for DerivePlugin {
    fn as_dyn_macro_plugin<'a>(self: Arc<Self>) -> Arc<dyn MacroPlugin + 'a>
    where
        Self: 'a,
    {
        self
    }
}
impl SemanticPlugin for DerivePlugin {}

/// Adds an implementation for all requested derives for the type.
fn generate_derive_code_for_type(
    db: &dyn SyntaxGroup,
    ident: ast::TerminalIdentifier,
    attributes: AttributeList,
) -> PluginResult {
    let mut diagnostics = vec![];
    let mut impls = vec![];
    for attr in attributes.elements(db) {
        if attr.attr(db).text(db) == "derive" {
            if let ast::OptionAttributeArgs::AttributeArgs(args) = attr.args(db) {
                for arg in args.arg_list(db).elements(db) {
                    if let ast::Expr::Path(expr) = arg {
                        if let [ast::PathSegment::Simple(segment)] = &expr.elements(db)[..] {
                            let name = ident.text(db);
                            let derived = segment.ident(db).text(db);
                            if matches!(derived.as_str(), "Copy" | "Drop") {
                                impls.push(format!(
                                    "impl {name}{derived} of {derived}::<{name}>;\n"
                                ));
                            }
                        } else {
                            diagnostics.push(PluginDiagnostic {
                                stable_ptr: expr.stable_ptr().untyped(),
                                message: "Expected a single segment.".into(),
                            });
                        }
                    } else {
                        diagnostics.push(PluginDiagnostic {
                            stable_ptr: arg.stable_ptr().untyped(),
                            message: "Expected path.".into(),
                        });
                    }
                }
            } else {
                diagnostics.push(PluginDiagnostic {
                    stable_ptr: attr.args(db).stable_ptr().untyped(),
                    message: "Expected args.".into(),
                });
            }
        }
    }
    PluginResult {
        code: if impls.is_empty() {
            None
        } else {
            Some(PluginGeneratedFile {
                name: "impls".into(),
                content: impls.join(""),
                aux_data: DynGeneratedFileAuxData(Arc::new(TrivialPluginAuxData {})),
            })
        },
        diagnostics,
        remove_original_item: false,
    }
}