fix(yt_dlp/post_processors): Register in python

We need to tell yt_dlp about our post processors, as they would
otherwise not take full effect. For example, changing the title would
previously only have changed the title in the *in-memory* info json, the
actual file on disk (video and .info.json) would still have the old
title, as yt_dlp did not know about our post processor.

Registering it via their api also has the upside of being able to
determine when to run.

1 files changed, 106 insertions, 14 deletions

diff --git a/crates/yt_dlp/src/post_processors/mod.rs b/crates/yt_dlp/src/post_processors/mod.rs
index 65801c2..575dc45 100644
--- a/crates/yt_dlp/src/post_processors/mod.rs
+++ b/crates/yt_dlp/src/post_processors/mod.rs
@@ -8,23 +8,115 @@
 // You should have received a copy of the License along with this program.
 // If not, see <https://www.gnu.org/licenses/gpl-3.0.txt>.
 
-use crate::InfoJson;
-
 pub mod dearrow;
 
-pub trait PostProcessor: std::fmt::Debug + Send {
-    /// Process a [`InfoJson`] object and return the updated one.
-    ///
-    /// # Errors
-    /// If the processing steps failed.
-    fn process(&self, info: InfoJson) -> Result<InfoJson, Error>;
+#[macro_export]
+macro_rules! pydict_get {
+    (@$vm:expr, $value:expr, $name:literal, $into:ident) => {{
+        match $value.get_item($name, $vm) {
+            Ok(val) => $crate::pydict_cast!(val, $into),
+            Err(_) => panic!(
+                concat!(
+                    "Expected '",
+                    $name,
+                    "' to be a key for the'",
+                    stringify!($value),
+                    "' py dictionary: {:#?}"
+                ),
+                $value
+            ),
+        }
+    }};
+}
 
-    /// The supported extractors for this post processor
-    fn extractors(&self) -> &'static [&'static str];
+#[macro_export]
+macro_rules! pydict_cast {
+    ($value:expr, $into:ident) => {{
+        match $value.downcast::<$into>() {
+            Ok(result) => result,
+            Err(val) => panic!(
+                concat!(
+                    "Expected to be able to downcast value ({:#?}) as ",
+                    stringify!($into)
+                ),
+                val
+            ),
+        }
+    }};
+    (@ref $value:expr, $into:ident) => {{
+        match $value.downcast_ref::<$into>() {
+            Some(result) => result,
+            None => panic!(
+                concat!(
+                    "Expected to be able to downcast value ({:#?}) as ",
+                    stringify!($into)
+                ),
+                $value
+            ),
+        }
+    }};
 }
 
-#[derive(thiserror::Error, Debug)]
-pub enum Error {
-    #[error("Failed to access a api: {0}")]
-    Get(#[from] reqwest::Error),
+#[macro_export]
+macro_rules! wrap_post_processor {
+    ($name:literal, $unwrap:ident, $wrapped:ident) => {
+        use $crate::progress_hook::__priv::vm;
+
+        /// # Errors
+        /// - If the underlying function returns an error.
+        /// - If python operations fail.
+        pub fn $wrapped(vm: &vm::VirtualMachine) -> vm::PyResult<vm::PyObjectRef> {
+            fn actual_processor(
+                mut input: vm::function::FuncArgs,
+                vm: &vm::VirtualMachine,
+            ) -> vm::PyResult<vm::PyRef<vm::builtins::PyDict>> {
+                let input = input
+                    .args
+                    .remove(0)
+                    .downcast::<vm::builtins::PyDict>()
+                    .expect("Should be a py dict");
+
+                let output = match unwrapped_process(input, vm) {
+                    Ok(ok) => ok,
+                    Err(err) => {
+                        return Err(vm.new_runtime_error(err.to_string()));
+                    }
+                };
+
+                Ok(output)
+            }
+
+            let scope = vm.new_scope_with_builtins();
+
+            scope.globals.set_item(
+                "actual_processor",
+                vm.new_function("actual_processor", actual_processor).into(),
+                vm,
+            )?;
+
+            let local_scope = scope.clone();
+            vm.run_code_string(
+                local_scope,
+                format!(
+                    "
+import yt_dlp
+
+class {}(yt_dlp.postprocessor.PostProcessor):
+    def run(self, info):
+        info = actual_processor(info)
+        return [], info
+
+inst = {}()
+",
+                    $name, $name
+                ).as_str(),
+                "<embedded post processor initializing code>".to_owned(),
+            )?;
+
+            Ok(scope
+                .globals
+                .get_item("inst", vm)
+                .expect("We just declared it"))
+        }
+    };
 }