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use super::hb_font_t;
use super::ot_shape::{shape_internal, ShapeContext};
use super::ot_shape_plan::hb_ot_shape_plan_t;
use crate::{script, Feature, GlyphBuffer, UnicodeBuffer};

/// Shapes the buffer content using provided font and features.
///
/// Consumes the buffer. You can then run [`GlyphBuffer::clear`] to get the [`UnicodeBuffer`] back
/// without allocating a new one.
///
/// If you plan to shape multiple strings using the same [`Face`] prefer [`shape_with_plan`].
/// This is because [`ShapePlan`] initialization is pretty slow and should preferably be called
/// once for each [`Face`].
pub fn shape(face: &hb_font_t, features: &[Feature], mut buffer: UnicodeBuffer) -> GlyphBuffer {
    buffer.0.guess_segment_properties();
    let plan = hb_ot_shape_plan_t::new(
        face,
        buffer.0.direction,
        buffer.0.script,
        buffer.0.language.as_ref(),
        features,
    );
    shape_with_plan(face, &plan, buffer)
}

/// Shapes the buffer content using the provided font and plan.
///
/// Consumes the buffer. You can then run [`GlyphBuffer::clear`] to get the [`UnicodeBuffer`] back
/// without allocating a new one.
///
/// It is up to the caller to ensure that the shape plan matches the properties of the provided
/// buffer, otherwise the shaping result will likely be incorrect.
///
/// # Panics
///
/// Will panic when debugging assertions are enabled if the buffer and plan have mismatched
/// properties.
pub fn shape_with_plan(
    face: &hb_font_t,
    plan: &hb_ot_shape_plan_t,
    buffer: UnicodeBuffer,
) -> GlyphBuffer {
    let mut buffer = buffer.0;
    buffer.guess_segment_properties();

    debug_assert_eq!(buffer.direction, plan.direction);
    debug_assert_eq!(
        buffer.script.unwrap_or(script::UNKNOWN),
        plan.script.unwrap_or(script::UNKNOWN)
    );

    if buffer.len > 0 {
        // Save the original direction, we use it later.
        let target_direction = buffer.direction;
        shape_internal(&mut ShapeContext {
            plan,
            face,
            buffer: &mut buffer,
            target_direction,
        });
    }

    GlyphBuffer(buffer)
}