//! Error types for anatomy file reading

use std::io;
use std::path::PathBuf;
use thiserror::Error;

/// Errors that can occur when reading FreeSurfer anatomy files
#[derive(Debug, Error)]
pub enum AnatomyError {
    /// I/O error during file operations
    #[error("I/O error: {0}")]
    Io(#[from] io::Error),

    /// Invalid magic number in file header
    #[error("Invalid magic number in file: expected {expected:?}, found {found:?}")]
    InvalidMagic {
        /// The expected magic bytes for the file format
        expected: Vec<u8>,
        /// The actual magic bytes found in the file
        found: Vec<u8>,
    },

    /// Surface file not found
    #[error("Surface file not found: {path}")]
    SurfaceNotFound {
        /// Path to the missing surface file
        path: PathBuf,
    },

    /// Annotation file not found
    #[error("Annotation file not found: {path}")]
    AnnotationNotFound {
        /// Path to the missing annotation file
        path: PathBuf,
    },

    /// Curvature file not found
    #[error("Curvature file not found: {path}")]
    CurvatureNotFound {
        /// Path to the missing curvature file
        path: PathBuf,
    },

    /// Invalid FreeSurfer subject directory
    #[error("Invalid FreeSurfer subject directory: {path}")]
    InvalidSubjectDir {
        /// Path to the invalid subject directory
        path: PathBuf,
    },

    /// Surface not loaded
    #[error("Surface not loaded: {hemisphere:?} {surface_type:?}")]
    SurfaceNotLoaded {
        /// The hemisphere (left or right) of the missing surface
        hemisphere: super::Hemisphere,
        /// The type of surface (e.g., pial, white, inflated) that was not loaded
        surface_type: super::SurfaceType,
    },

    /// Annotation not loaded
    #[error("Annotation not loaded: {hemisphere:?} {atlas}")]
    AnnotationNotLoaded {
        /// The hemisphere (left or right) of the missing annotation
        hemisphere: super::Hemisphere,
        /// The atlas name (e.g., aparc, aparc.a2009s) that was not loaded
        atlas: String,
    },

    /// Invalid vertex count
    #[error("Invalid vertex count: expected {expected}, found {found}")]
    InvalidVertexCount {
        /// The expected number of vertices
        expected: usize,
        /// The actual number of vertices found
        found: usize,
    },

    /// Invalid face count
    #[error("Invalid face count: found {count}")]
    InvalidFaceCount {
        /// The invalid face count found in the file
        count: usize,
    },

    /// Unsupported file format version
    #[error("Unsupported format version: {version}")]
    UnsupportedVersion {
        /// The unsupported version number encountered
        version: i32,
    },

    /// Color table parsing error
    #[error("Color table parsing error: {message}")]
    ColorTableError {
        /// Description of the color table parsing error
        message: String,
    },
}

/// Result type for anatomy operations
pub type Result<T> = std::result::Result<T, AnatomyError>;