throwable.rs

use alloc::{boxed::Box, format, vec, vec::Vec};

use java_class_proto::{JavaFieldProto, JavaMethodProto};
use jvm::{Array, ClassInstance, ClassInstanceRef, Jvm, Result, runtime::JavaLangString};

use crate::{
    RuntimeClassProto, RuntimeContext,
    classes::java::{
        io::{PrintStream, PrintWriter},
        lang::String,
    },
};

// class java.lang.Throwable
pub struct Throwable;

impl Throwable {
    pub fn as_proto() -> RuntimeClassProto {
        RuntimeClassProto {
            name: "java/lang/Throwable",
            parent_class: Some("java/lang/Object"),
            interfaces: vec![],
            methods: vec![
                JavaMethodProto::new("<init>", "()V", Self::init, Default::default()),
                JavaMethodProto::new("<init>", "(Ljava/lang/String;)V", Self::init_with_message, Default::default()),
                JavaMethodProto::new("toString", "()Ljava/lang/String;", Self::to_string, Default::default()),
                JavaMethodProto::new(
                    "fillInStackTrace",
                    "()Ljava/lang/Throwable;",
                    Self::fill_in_stack_trace,
                    Default::default(),
                ),
                JavaMethodProto::new("printStackTrace", "()V", Self::print_stack_trace, Default::default()),
                JavaMethodProto::new(
                    "printStackTrace",
                    "(Ljava/io/PrintStream;)V",
                    Self::print_stack_trace_to_print_stream,
                    Default::default(),
                ),
                JavaMethodProto::new(
                    "printStackTrace",
                    "(Ljava/io/PrintWriter;)V",
                    Self::print_stack_trace_to_print_writer,
                    Default::default(),
                ),
            ],
            fields: vec![
                JavaFieldProto::new("detailMessage", "Ljava/lang/String;", Default::default()),
                JavaFieldProto::new("stackTrace", "[Ljava/lang/String;", Default::default()),
            ],
            access_flags: Default::default(),
        }
    }

    async fn init(jvm: &Jvm, _: &mut RuntimeContext, this: ClassInstanceRef<Self>) -> Result<()> {
        tracing::debug!("java.lang.Throwable::<init>({:?})", &this);

        let _: () = jvm.invoke_special(&this, "java/lang/Object", "<init>", "()V", ()).await?;

        let _: ClassInstanceRef<Self> = jvm.invoke_virtual(&this, "fillInStackTrace", "()Ljava/lang/Throwable;", ()).await?;

        Ok(())
    }

    async fn init_with_message(jvm: &Jvm, _: &mut RuntimeContext, mut this: ClassInstanceRef<Self>, message: ClassInstanceRef<String>) -> Result<()> {
        tracing::debug!("java.lang.Throwable::<init>({:?}, {:?})", &this, &message);

        let _: () = jvm.invoke_special(&this, "java/lang/Object", "<init>", "()V", ()).await?;

        jvm.put_field(&mut this, "detailMessage", "Ljava/lang/String;", message).await?;

        let _: ClassInstanceRef<Self> = jvm.invoke_virtual(&this, "fillInStackTrace", "()Ljava/lang/Throwable;", ()).await?;

        Ok(())
    }

    async fn fill_in_stack_trace(jvm: &Jvm, _: &mut RuntimeContext, mut this: ClassInstanceRef<Self>) -> Result<ClassInstanceRef<Self>> {
        tracing::debug!("java.lang.Throwable::fillInStackTrace({:?})", &this);

        let stack_trace = jvm.stack_trace();
        let mut stack_trace_array = jvm.instantiate_array("Ljava/lang/String;", stack_trace.len()).await?;
        for (i, line) in stack_trace.iter().enumerate() {
            let java_line = JavaLangString::from_rust_string(jvm, line).await?;
            jvm.store_array(&mut stack_trace_array, i, core::iter::once(java_line)).await?;
        }
        jvm.put_field(&mut this, "stackTrace", "[Ljava/lang/String;", stack_trace_array).await?;

        Ok(this)
    }

    async fn print_stack_trace(jvm: &Jvm, _: &mut RuntimeContext, this: ClassInstanceRef<Self>) -> Result<()> {
        tracing::debug!("java.lang.Throwable::printStackTrace({:?})", &this);

        let err: ClassInstanceRef<PrintStream> = jvm.get_static_field("java/lang/System", "err", "Ljava/io/PrintStream;").await?;

        let _: () = jvm.invoke_virtual(&this, "printStackTrace", "(Ljava/io/PrintStream;)V", (err,)).await?;

        Ok(())
    }

    async fn print_stack_trace_to_print_stream(
        jvm: &Jvm,
        _: &mut RuntimeContext,
        this: ClassInstanceRef<Self>,
        stream: ClassInstanceRef<PrintStream>,
    ) -> Result<()> {
        tracing::debug!("java.lang.Throwable::printStackTrace({:?}, {:?})", &this, &stream);

        Self::do_print_stack_trace(jvm, this, stream.into()).await?;

        Ok(())
    }

    async fn print_stack_trace_to_print_writer(
        jvm: &Jvm,
        _: &mut RuntimeContext,
        this: ClassInstanceRef<Self>,
        writer: ClassInstanceRef<PrintWriter>,
    ) -> Result<()> {
        tracing::debug!("java.lang.Throwable::printStackTrace({:?}, {:?})", &this, &writer);

        Self::do_print_stack_trace(jvm, this, writer.into()).await?;

        Ok(())
    }

    async fn to_string(jvm: &Jvm, _: &mut RuntimeContext, this: ClassInstanceRef<Self>) -> Result<ClassInstanceRef<String>> {
        tracing::debug!("java.lang.Throwable::toString({:?})", &this);

        let class = jvm.invoke_virtual(&this, "getClass", "()Ljava/lang/Class;", ()).await?;
        let class_name = jvm.invoke_virtual(&class, "getName", "()Ljava/lang/String;", ()).await?;

        let message: ClassInstanceRef<String> = jvm.get_field(&this, "detailMessage", "Ljava/lang/String;").await?;

        let class_name = JavaLangString::to_rust_string(jvm, &class_name).await?;
        let message = if message.is_null() {
            class_name
        } else {
            let message = JavaLangString::to_rust_string(jvm, &message).await?;
            if message.is_empty() {
                class_name
            } else {
                format!("{class_name}: {message}")
            }
        };

        let message = JavaLangString::from_rust_string(jvm, &message).await?;

        Ok(message.into())
    }

    async fn do_print_stack_trace(jvm: &Jvm, this: ClassInstanceRef<Self>, stream_or_writer: Box<dyn ClassInstance>) -> Result<()> {
        let stack_trace: ClassInstanceRef<Array<ClassInstanceRef<String>>> = jvm.get_field(&this, "stackTrace", "[Ljava/lang/String;").await?;

        // TODO we can call println(Ljava/lang/Object;)V
        let string: ClassInstanceRef<String> = jvm.invoke_virtual(&this, "toString", "()Ljava/lang/String;", ()).await?;
        let _: () = jvm
            .invoke_virtual(&stream_or_writer, "println", "(Ljava/lang/String;)V", (string,))
            .await?;

        if !stack_trace.is_null() {
            let length = jvm.array_length(&stack_trace).await?;
            let lines: Vec<ClassInstanceRef<String>> = jvm.load_array(&stack_trace, 0, length).await?;
            for line_ref in lines {
                let line = JavaLangString::to_rust_string(jvm, &line_ref).await?;
                let line = format!("\tat {line}");
                let line = JavaLangString::from_rust_string(jvm, &line).await?;
                let _: () = jvm.invoke_virtual(&stream_or_writer, "println", "(Ljava/lang/String;)V", (line,)).await?;
            }
        }

        Ok(())
    }
}