//! TRANSITIONAL(plan-05): the pre-`params!` parameter surface.
//!
//! `params!` generates a `SetupParams` shim and the snapshot extractors are
//! built on `CpuParams` / `get_param`, so this whole module stays until the
//! `Effect` v2 / graph swap removes `FrameDataContext` and `kernel_params!`
//! (the last `get_param` / `FromParam` consumers).

use std::{
	any::TypeId,
	collections::HashMap,
	fmt::Debug,
	hash::Hash,
	ptr,
	sync::{OnceLock, RwLock},
};

use after_effects::{InData, OutData, Parameters, sys::PF_Pixel};
use premiere::{self as pr};

use crate::types::Pixel;

pub trait SetupParams: Sized + Eq + Hash + Copy + Debug + Into<usize> + 'static {
	fn to_index(self) -> usize {
		self.into()
	}

	fn setup(params: &mut Parameters<Self>, in_data: InData, out_data: OutData) -> Result<(), after_effects::Error>;
}

pub trait FromParam: Sized {
	fn extract(p: pr::Param) -> Option<Self>;
}

impl FromParam for i32 {
	fn extract(p: pr::Param) -> Option<Self> {
		match p {
			pr::Param::Int32(v) => Some(v),
			// Premiere GPU returns popups as Float32; coerce instead of failing.
			pr::Param::Float32(v) => Some(v as i32),
			_ => None,
		}
	}
}

impl FromParam for i64 {
	fn extract(p: pr::Param) -> Option<Self> {
		if let pr::Param::Int64(v) = p { Some(v) } else { None }
	}
}

impl FromParam for f32 {
	fn extract(p: pr::Param) -> Option<Self> {
		if let pr::Param::Float32(v) = p {
			Some(v)
		} else if let pr::Param::Float64(v) = p {
			Some(v as f32)
		} else {
			None
		}
	}
}

impl FromParam for f64 {
	fn extract(p: pr::Param) -> Option<Self> {
		if let pr::Param::Float64(v) = p { Some(v) } else { None }
	}
}

impl FromParam for bool {
	fn extract(p: pr::Param) -> Option<Self> {
		if let pr::Param::Bool(v) = p { Some(v) } else { None }
	}
}

impl FromParam for u32 {
	fn extract(p: pr::Param) -> Option<Self> {
		if let pr::Param::Int32(v) = p {
			if v >= 0 { Some(v as u32) } else { None }
		} else {
			None
		}
	}
}

impl FromParam for (f32, f32) {
	fn extract(p: premiere::Param) -> Option<Self> {
		if let pr::Param::Point(v) = p { Some((v.x as f32, v.y as f32)) } else { None }
	}
}

impl FromParam for (f64, f64) {
	fn extract(p: premiere::Param) -> Option<Self> {
		if let pr::Param::Point(v) = p { Some((v.x, v.y)) } else { None }
	}
}

impl FromParam for Pixel {
	fn extract(p: premiere::Param) -> Option<Self> {
		match p {
			pr::Param::MemoryPtr(v) => {
				if v.is_null() {
					None
				} else {
					let pf_pixel = unsafe { ptr::read(v as *const PF_Pixel) };
					Some(Pixel::from_pf_pixel(pf_pixel))
				}
			}
			pr::Param::Int32(v) => Some(Pixel::from_bytes32(v as u32)),
			pr::Param::Int64(v) => {
				#[cfg(debug_assertions)]
				{
					Pixel::debug_print_color(v);
				}

				Some(Pixel::from_u64_color(v as u64))
			}
			_ => None,
		}
	}
}

/// Per-`Params` map of enum discriminant → host param index, captured from the
/// AE `Parameters` registration order during param setup.
///
/// The Premiere GPU path reads params positionally via `GpuFilterData::param(i)`,
/// where `i` is the registration-order index — NOT the enum discriminant.
fn gpu_param_index_registry() -> &'static RwLock<HashMap<TypeId, HashMap<usize, usize>>> {
	static REG: OnceLock<RwLock<HashMap<TypeId, HashMap<usize, usize>>>> = OnceLock::new();
	REG.get_or_init(|| RwLock::new(HashMap::new()))
}

/// Record the discriminant → host-index map for `P`. Called once per param
/// setup by the adapter, after `Effect::params` has registered everything.
pub fn register_gpu_param_indices<P: SetupParams>(map: HashMap<usize, usize>) {
	if let Ok(mut reg) = gpu_param_index_registry().write() {
		reg.insert(TypeId::of::<P>(), map);
	}
}

/// Resolve a discriminant to its host param index for `P`. Falls back to the
/// discriminant itself when no map is registered (keeps `from_gpu` unit tests,
/// which never run param setup, unchanged).
fn gpu_param_index<P: SetupParams>(discriminant: usize) -> usize {
	gpu_param_index_registry()
		.read()
		.ok()
		.and_then(|reg| reg.get(&TypeId::of::<P>()).and_then(|m| m.get(&discriminant).copied()))
		.unwrap_or(discriminant)
}

pub fn get_param<T: FromParam + Default, Params: SetupParams>(filter: &pr::GpuFilterData, param: Params, render_params: &pr::RenderParams) -> T {
	let discriminant = param.to_index();
	let idx = gpu_param_index::<Params>(discriminant);
	let clip = render_params.clip_time();
	match filter.param(idx, clip) {
		Ok(p) => match T::extract(p) {
			Some(v) => v,
			None => {
				#[cfg(debug_assertions)]
				after_effects::log::warn!(
					"[params] discriminant {discriminant} (host idx {idx}): present but not the variant this kernel field expects; substituting Default (0)."
				);
				T::default()
			}
		},
		Err(_e) => {
			#[cfg(debug_assertions)]
			after_effects::log::warn!("[params] discriminant {discriminant} (host idx {idx}): lookup failed ({_e:?}); substituting Default (0).");
			T::default()
		}
	}
}

pub trait CpuParams<P: SetupParams> {
	fn float(&self, p: P) -> Result<f32, after_effects::Error>;
	fn angle(&self, p: P) -> Result<f32, after_effects::Error>;
	fn color(&self, p: P) -> Result<PF_Pixel, after_effects::Error>;
	fn point(&self, p: P) -> Result<(f32, f32), after_effects::Error>;
	fn checkbox(&self, p: P) -> Result<bool, after_effects::Error>;
	fn popup(&self, p: P) -> Result<i32, after_effects::Error>;
}

impl<P: SetupParams> CpuParams<P> for Parameters<'_, P> {
	fn float(&self, p: P) -> Result<f32, after_effects::Error> {
		Ok(self.get(p)?.as_float_slider()?.value() as f32)
	}

	fn angle(&self, p: P) -> Result<f32, after_effects::Error> {
		Ok(self.get(p)?.as_angle()?.value())
	}

	fn color(&self, p: P) -> Result<PF_Pixel, after_effects::Error> {
		Ok(self.get(p)?.as_color()?.value())
	}

	fn point(&self, p: P) -> Result<(f32, f32), after_effects::Error> {
		let v = self.get(p)?.as_point()?.value();
		Ok((v.0, v.1))
	}

	fn checkbox(&self, p: P) -> Result<bool, after_effects::Error> {
		Ok(self.get(p)?.as_checkbox()?.value())
	}

	fn popup(&self, p: P) -> Result<i32, after_effects::Error> {
		Ok(self.get(p)?.as_popup()?.value())
	}
}
