sim-lib-interference-solve 0.1.0

//! Immutable host storage for phasor component planes.

use crate::{ReferenceSolveError, complex::Complex64};

/// A host phasor component buffer was not a valid finite two-dimensional field.
#[derive(Clone, Debug, PartialEq)]
pub enum HostPhasorFieldError {
    /// A component plane dimension was zero.
    ZeroDimension {
        /// Rejected dimension.
        axis: &'static str,
    },
    /// The row/column product overflowed or did not match both component lengths.
    ShapeMismatch {
        /// Declared row count.
        rows: usize,
        /// Declared column count.
        columns: usize,
        /// Real component length.
        real_len: usize,
        /// Imaginary component length.
        imaginary_len: usize,
    },
    /// One component contained a NaN or infinity.
    NonFinite {
        /// Component plane.
        component: &'static str,
        /// Row-major cell index.
        index: usize,
        /// Rejected value.
        value: f64,
    },
}

/// A complete two-dimensional host phasor field.
///
/// Real and imaginary components are stored in separate flat `f64` buffers.
/// Both buffers use the same row-major index, `row * columns + column`.
#[derive(Clone, Debug, PartialEq)]
pub struct HostPhasorField {
    rows: usize,
    columns: usize,
    real: Vec<f64>,
    imaginary: Vec<f64>,
}

impl HostPhasorField {
    /// Admits complete finite row-major component planes.
    ///
    /// This is the explicit materialization boundary used by runtime tensor
    /// adapters. It performs no propagation and takes ownership of both
    /// buffers without copying them.
    pub fn from_component_planes(
        rows: usize,
        columns: usize,
        real: Vec<f64>,
        imaginary: Vec<f64>,
    ) -> Result<Self, HostPhasorFieldError> {
        if rows == 0 {
            return Err(HostPhasorFieldError::ZeroDimension { axis: "rows" });
        }
        if columns == 0 {
            return Err(HostPhasorFieldError::ZeroDimension { axis: "columns" });
        }
        let Some(cells) = rows.checked_mul(columns) else {
            return Err(HostPhasorFieldError::ShapeMismatch {
                rows,
                columns,
                real_len: real.len(),
                imaginary_len: imaginary.len(),
            });
        };
        if real.len() != cells || imaginary.len() != cells {
            return Err(HostPhasorFieldError::ShapeMismatch {
                rows,
                columns,
                real_len: real.len(),
                imaginary_len: imaginary.len(),
            });
        }
        for (component, values) in [("real", &real), ("imaginary", &imaginary)] {
            if let Some((index, value)) = values
                .iter()
                .copied()
                .enumerate()
                .find(|(_, value)| !value.is_finite())
            {
                return Err(HostPhasorFieldError::NonFinite {
                    component,
                    index,
                    value,
                });
            }
        }
        Ok(Self {
            rows,
            columns,
            real,
            imaginary,
        })
    }

    pub(crate) fn try_zeroed(rows: usize, columns: usize) -> Result<Self, ReferenceSolveError> {
        let cells = rows
            .checked_mul(columns)
            .expect("SamplingPlane has already checked rows * columns");
        let real = zeroed_component("real", cells)?;
        let imaginary = zeroed_component("imaginary", cells)?;
        Ok(Self {
            rows,
            columns,
            real,
            imaginary,
        })
    }

    pub(crate) fn set_index(&mut self, index: usize, value: Complex64) {
        let (real, imaginary) = value.components();
        self.real[index] = real;
        self.imaginary[index] = imaginary;
    }

    #[cfg(test)]
    pub(crate) fn from_test_components(
        rows: usize,
        columns: usize,
        real: Vec<f64>,
        imaginary: Vec<f64>,
    ) -> Self {
        let cells = rows.checked_mul(columns).expect("test shape must fit");
        assert_eq!(real.len(), cells);
        assert_eq!(imaginary.len(), cells);
        assert!(real.iter().chain(&imaginary).all(|value| value.is_finite()));
        Self {
            rows,
            columns,
            real,
            imaginary,
        }
    }

    /// Returns the number of rows.
    pub fn rows(&self) -> usize {
        self.rows
    }

    /// Returns the number of columns.
    pub fn columns(&self) -> usize {
        self.columns
    }

    /// Returns the number of cells in each component plane.
    pub fn len(&self) -> usize {
        self.real.len()
    }

    /// Returns whether the component planes contain no cells.
    ///
    /// Successfully solved fields are never empty because sampling-plane
    /// construction requires non-zero dimensions.
    pub fn is_empty(&self) -> bool {
        self.real.is_empty()
    }

    /// Borrows the flat row-major real component plane.
    pub fn real(&self) -> &[f64] {
        &self.real
    }

    /// Borrows the flat row-major imaginary component plane.
    pub fn imaginary(&self) -> &[f64] {
        &self.imaginary
    }

    /// Returns one cell's Cartesian components.
    pub fn cell(&self, row: usize, column: usize) -> Option<(f64, f64)> {
        let index = row.checked_mul(self.columns)?.checked_add(column)?;
        (row < self.rows && column < self.columns)
            .then(|| Complex64::new(self.real[index], self.imaginary[index]).components())
    }

    /// Consumes the field into its shape and component planes.
    pub fn into_component_planes(self) -> (usize, usize, Vec<f64>, Vec<f64>) {
        (self.rows, self.columns, self.real, self.imaginary)
    }
}

fn zeroed_component(
    component: &'static str,
    cells: usize,
) -> Result<Vec<f64>, ReferenceSolveError> {
    let mut values = Vec::new();
    values
        .try_reserve_exact(cells)
        .map_err(|_| ReferenceSolveError::AllocationFailed { component, cells })?;
    values.resize(cells, 0.0);
    Ok(values)
}

#[cfg(test)]
mod tests {
    use super::HostPhasorField;

    #[test]
    fn component_planes_share_one_row_major_shape() {
        let field = HostPhasorField {
            rows: 2,
            columns: 3,
            real: vec![0.0, 1.0, 2.0, 3.0, 4.0, 5.0],
            imaginary: vec![10.0, 11.0, 12.0, 13.0, 14.0, 15.0],
        };

        assert_eq!(field.rows(), 2);
        assert_eq!(field.columns(), 3);
        assert_eq!(field.len(), 6);
        assert!(!field.is_empty());
        assert_eq!(field.cell(1, 2), Some((5.0, 15.0)));
        assert_eq!(field.cell(2, 0), None);
        assert_eq!(field.cell(0, 3), None);
        assert_eq!(field.real(), &[0.0, 1.0, 2.0, 3.0, 4.0, 5.0]);
        assert_eq!(field.imaginary(), &[10.0, 11.0, 12.0, 13.0, 14.0, 15.0]);
    }
}