//! TRACES: NFR-ARCH-4
//! Typed export failures.
//!
//! Every variant is something a caller can act on or report. A batch export
//! runs unattended over hundreds of frames (FR-EXP-7), so "what went wrong
//! with which file" has to survive as data rather than as a log line.

use dr_types::{ColourSpace, ExportFormat};

#[derive(Debug, thiserror::Error)]
pub enum ExportError {
    #[error("frame buffer is {got} bytes, expected {expected}")]
    FrameSize { expected: usize, got: usize },

    #[error("frame has no pixels")]
    EmptyFrame,

    /// Asked for a format with no encoder in this build.
    ///
    /// Not a panic and not a silent substitution: the settings page offers
    /// AVIF and JPEG XL because FR-EXP-1 lists them, and a build without them
    /// should say so rather than quietly writing a JPEG under a `.avif` name.
    #[error("{} export is not supported yet", .0.label())]
    FormatUnsupported(ExportFormat),

    /// TRACES: FR-EXP-2
    /// The frame was rendered into one colour space and asked to be labelled
    /// another.
    ///
    /// Not a limitation of the encoders — all four spaces embed a correct
    /// profile. It is that the conversion happens in the shader, before the
    /// clip to 0..1, so a frame is in exactly one space by the time it gets
    /// here. The caller composes with `EditGraph::compose_for` to change which.
    #[error(
        "the frame was rendered in {} but a {} file was asked for",
        .rendered.label(),
        .requested.label()
    )]
    ColourSpaceMismatch {
        rendered: ColourSpace,
        requested: ColourSpace,
    },

    #[error("encoding failed: {0}")]
    Encode(String),
}