//! #[constitutional]属性宏实现

use proc_macro::TokenStream;
use quote::quote;
use syn::{parse_macro_input, ItemFn, AttributeArgs, Meta, NestedMeta, Lit};

/// 解析#[constitutional]属性参数
pub struct ConstitutionalArgs {
    pub clause: Option<String>,
    pub check: Option<String>,
    pub enforce: Option<String>,
}

impl ConstitutionalArgs {
    pub fn from_args(args: AttributeArgs) -> Self {
        let mut clause = None;
        let mut check = None;
        let mut enforce = None;

        for arg in args {
            if let NestedMeta::Meta(Meta::NameValue(nv)) = arg {
                let path_str = nv.path.get_ident().map(|i| i.to_string());
                
                match path_str.as_deref() {
                    Some("clause") => {
                        if let Lit::Str(lit) = &nv.lit {
                            clause = Some(lit.value());
                        }
                    }
                    Some("check") => {
                        if let Lit::Str(lit) = &nv.lit {
                            check = Some(lit.value());
                        }
                    }
                    Some("enforce") => {
                        if let Lit::Str(lit) = &nv.lit {
                            enforce = Some(lit.value());
                        }
                    }
                    _ => {}
                }
            }
        }

        Self {
            clause,
            check,
            enforce,
        }
    }
}

/// 实现#[constitutional]属性宏
pub fn constitutional_impl(attr: TokenStream, item: TokenStream) -> TokenStream {
    // 解析属性参数
    let args = parse_macro_input!(attr as AttributeArgs);
    let input = parse_macro_input!(item as ItemFn);
    let parsed_args = ConstitutionalArgs::from_args(args);

    let fn_vis = &input.vis;
    let fn_sig = &input.sig;
    let fn_block = &input.block;
    let fn_name = &input.sig.ident;

    // 生成宪法检查代码
    let clause_check = if let Some(clause) = parsed_args.clause {
        quote! {
            log::trace!("Invoking constitutional clause: {}", #clause);
        }
    } else {
        quote! {
            log::trace!("Invoking constitutional function: {}", stringify!(#fn_name));
        }
    };

    let constraint_check = if let Some(check_expr) = parsed_args.check {
        quote! {
            log::debug!("Checking constitutional constraint: {}", #check_expr);
            // 实际的约束验证逻辑
            // 在运行时检查宪法约束是否满足
            // 实际应该：
            // 1. 解析check_expr表达式
            // 2. 评估约束条件
            // 3. 如果不满足，抛出宪法异常
            // 4. 记录约束检查结果
        }
    } else {
        quote! {}
    };

    let enforcement = if let Some(enforcer) = parsed_args.enforce {
        quote! {
            log::debug!("Constitutional enforcer: {}", #enforcer);
            // 实际的执行逻辑
            // 在运行时执行宪法强制措施
            // 实际应该：
            // 1. 解析enforcer表达式
            // 2. 调用宪法强制执行器
            // 3. 如果执行失败，抛出异常
            // 4. 记录执行结果和日志
        }
    } else {
        quote! {}
    };

    // 生成最终代码
    let expanded = quote! {
        #fn_vis #fn_sig {
            #clause_check
            #constraint_check
            #enforcement

            // 原始函数体
            #fn_block
        }
    };

    TokenStream::from(expanded)
}