zencodec 0.1.19

//! Encoder configuration and encode jobs.

use alloc::boxed::Box;

use crate::format::ImageFormat;
use crate::{EncodeCapabilities, Metadata, ResourceLimits};
use zenpixels::PixelDescriptor;

use super::BoxedError;
use super::dyn_encoding::{AnimationFrameEncoderShim, DynAnimationFrameEncoder, DynEncoder};
use super::encoder::{AnimationFrameEncoder, Encoder};

// ===========================================================================
// Encoder configuration
// ===========================================================================

/// Reusable encoder configuration.
///
/// Implemented by each codec's config type. Config types are `Clone + Send +
/// Sync` with no lifetimes — store them in structs, share across threads.
///
/// Universal encoding parameters (quality, effort, lossless) have default
/// no-op implementations. Use the corresponding getter to check if the
/// codec accepted a value.
///
/// The `job()` method consumes the config and creates a per-operation
/// [`EncodeJob`] that owns it. Clone the config first if you need to
/// reuse it: `config.clone().job()`.
pub trait EncoderConfig: Clone + Send + Sync {
    /// The codec-specific error type.
    type Error: core::error::Error + Send + Sync + 'static;

    /// Per-operation job type. Owns all configuration including stop token.
    type Job: EncodeJob<Error = Self::Error>;

    /// The image format this encoder produces.
    fn format() -> ImageFormat;

    /// Pixel formats this encoder accepts natively (without internal conversion).
    ///
    /// Every descriptor in this list is a guarantee: the corresponding
    /// per-format encode trait is implemented and will work without format
    /// conversion. Must not be empty.
    fn supported_descriptors() -> &'static [PixelDescriptor];

    /// Encoder capabilities (metadata support, cancellation, etc.).
    ///
    /// Returns a static reference describing what this encoder supports.
    fn capabilities() -> &'static EncodeCapabilities {
        &EncodeCapabilities::EMPTY
    }

    /// Set encoding quality on a calibrated 0.0--100.0 scale.
    ///
    /// "Generic" because this is the codec-agnostic quality knob. Individual
    /// codecs may also have format-specific quality methods on their config types.
    ///
    /// # Note
    ///
    /// The default implementation is a no-op. Not all codecs support quality
    /// tuning. Use [`generic_quality()`](EncoderConfig::generic_quality) after
    /// calling this to verify the codec accepted the value -- it returns `None`
    /// if the codec does not support quality settings.
    fn with_generic_quality(self, _quality: f32) -> Self {
        self
    }

    /// Set encoding effort (higher = slower, better compression).
    ///
    /// "Generic" because this is the codec-agnostic effort knob. Individual
    /// codecs may also have format-specific effort/speed methods.
    ///
    /// Each codec maps this to its internal effort/speed scale.
    ///
    /// # Note
    ///
    /// The default implementation is a no-op. Not all codecs support effort
    /// tuning. Use [`generic_effort()`](EncoderConfig::generic_effort) after
    /// calling this to verify the codec accepted the value -- it returns `None`
    /// if the codec does not support effort settings.
    fn with_generic_effort(self, _effort: i32) -> Self {
        self
    }

    /// Enable or disable lossless encoding.
    ///
    /// When lossless is enabled, quality is ignored.
    ///
    /// # Note
    ///
    /// The default implementation is a no-op. Not all codecs support lossless
    /// mode. Use [`is_lossless()`](EncoderConfig::is_lossless) after calling
    /// this to verify the codec accepted the value -- it returns `None` if the
    /// codec does not support lossless encoding.
    fn with_lossless(self, _lossless: bool) -> Self {
        self
    }

    /// Set independent alpha channel quality on a calibrated 0.0--100.0 scale.
    ///
    /// # Note
    ///
    /// The default implementation is a no-op. Not all codecs support separate
    /// alpha quality. Use [`alpha_quality()`](EncoderConfig::alpha_quality) after
    /// calling this to verify the codec accepted the value -- it returns `None`
    /// if the codec does not support alpha quality settings.
    fn with_alpha_quality(self, _quality: f32) -> Self {
        self
    }

    /// Current generic quality value, or `None` if the codec has no quality tuning.
    fn generic_quality(&self) -> Option<f32> {
        None
    }

    /// Current generic effort value, or `None` if the codec has no effort tuning.
    fn generic_effort(&self) -> Option<i32> {
        None
    }

    /// Current lossless setting, or `None` if the codec doesn't support it.
    fn is_lossless(&self) -> Option<bool> {
        None
    }

    /// Current alpha quality value, or `None` if unsupported.
    fn alpha_quality(&self) -> Option<f32> {
        None
    }

    /// Create a per-operation job, consuming the config.
    ///
    /// The job owns the config and all configuration set on it
    /// (stop token, limits, metadata).
    fn job(self) -> Self::Job;
}

// ===========================================================================
// Encode job
// ===========================================================================

/// Per-operation encode job.
///
/// Created by [`EncoderConfig::job()`]. Binds metadata, limits, and
/// cancellation for a single encode operation. Produces either an `Enc`
/// (single image via per-format traits) or a `AnimationFrameEnc` (animation
/// via full-frame encoder).
pub trait EncodeJob: Sized {
    /// The codec-specific error type.
    type Error: core::error::Error + Send + Sync + 'static;

    /// Single-image encoder type (implements [`Encoder`]).
    type Enc: Sized + 'static;

    /// Full-frame animation encoder type (implements [`AnimationFrameEncoder`]).
    ///
    /// Must be `'static` and `Send` — frame encoders own their configuration
    /// (clone configs, convert stop tokens to owned form). This lets
    /// callers use the encoder independently of the job's scope and across
    /// thread boundaries (e.g., in pipeline `Sink` implementations).
    type AnimationFrameEnc: Sized + Send + 'static;

    /// Set cooperative cancellation token.
    ///
    /// [`StopToken`](almost_enough::StopToken) is `Clone + Send + Sync + 'static` —
    /// an owned, type-erased stop. Convert any `Stop + Clone + 'static` with
    /// `stop.into_token()` or `StopToken::new(stop)`.
    fn with_stop(self, stop: crate::StopToken) -> Self;

    /// Override resource limits for this operation.
    fn with_limits(self, limits: ResourceLimits) -> Self;

    /// Set encode security policy (controls metadata embedding, etc.).
    ///
    /// # Note
    ///
    /// The default implementation is a no-op that returns `self` unchanged.
    /// Not all codecs implement policy support. Check the codec's documentation
    /// or [`EncodeCapabilities`](crate::EncodeCapabilities) to determine whether
    /// the codec honors policy settings. Calling this on a codec that does not
    /// implement it will silently have no effect.
    fn with_policy(self, _policy: crate::EncodePolicy) -> Self {
        self
    }

    /// Set metadata (ICC, EXIF, XMP) to embed in the output.
    ///
    /// Takes ownership — callers that need to reuse the metadata should
    /// `.clone()` before passing. The `Arc<[u8]>` fields inside `Metadata`
    /// make cloning cheap (ref-count bump, no byte copying).
    ///
    /// The codec embeds what the format supports, silently skips the rest.
    fn with_metadata(self, meta: Metadata) -> Self;

    /// Set animation canvas dimensions.
    ///
    /// For full-frame animation, this sets the expected frame dimensions.
    /// All pushed frames must match these dimensions. Default: canvas =
    /// first frame's dimensions.
    fn with_canvas_size(self, _width: u32, _height: u32) -> Self {
        self
    }

    /// Set animation loop count.
    ///
    /// - `Some(0)` = loop forever
    /// - `Some(n)` = loop `n` times
    /// - `None` = format default
    ///
    /// Must be set before [`animation_frame_encoder()`](EncodeJob::animation_frame_encoder)
    /// because formats write the loop count before frame data.
    fn with_loop_count(self, _count: Option<u32>) -> Self {
        self
    }

    /// Access codec-specific extensions for this job.
    ///
    /// Returns a reference to a `'static` extension type stored inside
    /// the job. Callers downcast via `Any::downcast_ref` to the codec's
    /// extension type. Returns `None` if the codec has no extensions.
    ///
    /// The extension type must be `'static` (no borrowed data), but the
    /// *reference* borrows from the job, which is fine.
    ///
    /// # Example
    ///
    /// ```rust,ignore
    /// if let Some(ext) = job.extensions() {
    ///     if let Some(jpeg) = ext.downcast_ref::<JpegEncodeExtensions>() {
    ///         // read codec-specific state
    ///     }
    /// }
    /// ```
    fn extensions(&self) -> Option<&dyn core::any::Any> {
        None
    }

    /// Mutable access to codec-specific extensions.
    ///
    /// # Example
    ///
    /// ```rust,ignore
    /// if let Some(ext) = job.extensions_mut() {
    ///     if let Some(jpeg) = ext.downcast_mut::<JpegEncodeExtensions>() {
    ///         jpeg.optimize_huffman = true;
    ///     }
    /// }
    /// ```
    fn extensions_mut(&mut self) -> Option<&mut dyn core::any::Any> {
        None
    }

    /// Create a one-shot encoder for a single image.
    fn encoder(self) -> Result<Self::Enc, Self::Error>;

    /// Create a full-frame animation encoder.
    ///
    /// Set loop count and canvas size before calling this.
    fn animation_frame_encoder(self) -> Result<Self::AnimationFrameEnc, Self::Error>;

    // --- Type-erased convenience methods ---

    /// Create a type-erased one-shot encoder.
    ///
    /// Returns a boxed [`DynEncoder`] that accepts any [`PixelSlice`](zenpixels::PixelSlice)
    /// (type-erased) and produces encoded output. All configuration —
    /// both universal ([`EncoderConfig::with_generic_quality`]) and
    /// codec-specific (methods on the concrete config type) — is
    /// applied *before* this call.
    ///
    /// Only available when `Enc` implements [`Encoder`].
    ///
    /// # Example
    ///
    /// ```rust,ignore
    /// // Codec-specific options on the concrete type
    /// let config = JpegConfig::new()
    ///     .set_chroma_subsampling(ChromaSubsampling::Yuv444)
    ///     .with_generic_quality(92.0);
    ///
    /// // Erase the codec type
    /// let encode = config.job()
    ///     .with_metadata(meta)
    ///     .dyn_encoder()?;
    ///
    /// // No generics from here on
    /// let output = encode.encode(pixels)?;
    /// ```
    fn dyn_encoder(self) -> Result<Box<dyn DynEncoder>, BoxedError>
    where
        Self::Enc: Encoder + Send,
    {
        let enc = self.encoder().map_err(|e| Box::new(e) as BoxedError)?;
        Ok(Box::new(super::dyn_encoding::EncoderShim(enc)))
    }

    /// Create a type-erased full-frame animation encoder.
    ///
    /// Only available when `AnimationFrameEnc` implements [`AnimationFrameEncoder`].
    ///
    /// # Example
    ///
    /// ```rust,ignore
    /// let mut enc = config.job()
    ///     .with_loop_count(Some(0))
    ///     .dyn_animation_frame_encoder()?;
    ///
    /// enc.push_frame(frame1_pixels, 100, None)?;
    /// enc.push_frame(frame2_pixels, 100, None)?;
    /// let output = enc.finish(None)?;
    /// ```
    fn dyn_animation_frame_encoder(self) -> Result<Box<dyn DynAnimationFrameEncoder>, BoxedError>
    where
        Self::AnimationFrameEnc: AnimationFrameEncoder + Send,
    {
        let enc = self
            .animation_frame_encoder()
            .map_err(|e| Box::new(e) as BoxedError)?;
        Ok(Box::new(AnimationFrameEncoderShim(enc)))
    }
}