use image_rs::{ImageError as IError, error};
use std::fmt;
use thiserror::Error;

use crate::image::PixelFormat;

#[derive(Error, Debug)]
pub enum LlsError {
    SingularMatrix,
}

#[derive(Error, Debug, Clone, PartialEq, Eq)]
pub enum InversionError {
    SingularMatrix,
    EmptyMatrix,
}

impl fmt::Display for LlsError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            LlsError::SingularMatrix => write!(f, "Matrix is singular and cannot be inverted."),
        }
    }
}

impl fmt::Display for InversionError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            InversionError::SingularMatrix => {
                write!(f, "Matrix is singular and cannot be inverted.")
            }
            InversionError::EmptyMatrix => write!(f, "Matrix is empty and cannot be inverted."),
        }
    }
}

#[derive(Error, Debug)]
pub enum ImageError {
    #[error("I/O error: {0}")]
    Io(#[from] std::io::Error),

    #[error("Image file error: {0}")]
    Image(#[from] IError),

    #[error("EXR file error: {0}")]
    Exr(#[from] exr::error::Error),

    #[error("QOI file error: {0}")]
    Qoi(String),

    #[error("Pixel format error: {0}")]
    PixelFormat(#[from] PixelFormatError),

    #[error("Unsupported operation: {0}")]
    Unsupported(String),

    #[error("Mismatched dimensions or channels: {0}")]
    Mismatch(String),

    #[error("Channel '{0}' not found in image")]
    ChannelNotFound(String),
}

/// Describes an error related to an unexpected or unsupported pixel format.
#[derive(Error, Debug, Clone, PartialEq, Eq)]
pub enum PixelFormatError {
    #[error("Unsupported operation '{operation}' for pixel format {actual:?}. Reason: {reason}")]
    UnsupportedOperation {
        operation: String,
        actual: PixelFormat,
        reason: String,
    },

    #[error("Invalid conversion from pixel format {from:?} to {to:?}.")]
    InvalidConversion { from: PixelFormat, to: PixelFormat },

    #[error(
        "Internal invariant violated: image format is {expected:?} but pixel data is of a different type."
    )]
    InternalFormatMismatch { expected: PixelFormat },
}