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//! Error declarations

use std::{
    convert::From,
    fmt::{Display, Formatter},
    string::String
};

/// Represents a BPX error
#[derive(Debug)]
pub enum Error
{
    /// Describes a checksum error
    ///
    /// #### Arguments
    /// * expected checksum value
    /// * actual checksum value
    Checksum(u32, u32),

    /// Describes an io error
    ///
    /// #### Arguments
    /// * the error that occured
    Io(std::io::Error),

    /// Describes a type conversion error (Structured Data)
    ///
    /// #### Arguments
    /// * expected type name
    /// * actual type name
    TypeError(&'static str, &'static str),

    /// Describes too many props or values attempted to be written as part of an Object or Array (Structured Data) (ie exceeds 255)
    ///
    /// #### Arguments
    /// * actual count of props
    PropCountExceeded(usize),

    /// Describes a missing property in an object (Structured Data)
    ///
    /// #### Arguments
    /// * name of missing prop
    MissingProp(&'static str),

    /// Describes a data truncation error, this means a section or the file itself has been truncated
    ///
    /// #### Arguments
    /// * last operation name before failure
    Truncation(&'static str),

    /// Describes a data corruption error, this means an impossible byte or sequence of bytes has been found
    ///
    /// #### Arguments
    /// * message
    Corruption(String),

    /// Describes an utf8 decoding/encoding error
    ///
    /// #### Arguments
    /// * last operation name before failure
    Utf8(&'static str),

    /// Describes an operation or flag that is currently unsupported
    ///
    /// #### Arguments
    /// * message
    Unsupported(String),

    /// Describes a section that is too large to be written (ie exceeds 2 pow 32 / 4Gb)
    ///
    /// #### Arguments
    /// * actual size of section
    Capacity(usize),

    /// Describes a compression error
    ///
    /// #### Arguments
    /// * error description string
    Deflate(&'static str),

    /// Describes a decompression error
    ///
    /// #### Arguments
    /// * error description string
    Inflate(&'static str),

    /// Describes a generic unknown error
    ///
    /// #### Arguments
    /// * error message
    Other(String)
}

impl From<std::io::Error> for Error
{
    fn from(e: std::io::Error) -> Self
    {
        return Error::Io(e);
    }
}

impl From<&str> for Error
{
    fn from(e: &str) -> Self
    {
        return Error::Other(String::from(e));
    }
}

impl Display for Error
{
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result
    {
        return match self {
            Error::Checksum(expected, actual) => f.write_str(&format!(
                "checksum validation failed (expected {}, got {})",
                expected, actual
            )),
            Error::Io(e) => f.write_str(&format!("io error ({})", e)),
            Error::TypeError(expected, actual) => {
                f.write_str(&format!("incompatible types (expected {}, got {})", expected, actual))
            },
            Error::PropCountExceeded(v) => f.write_str(&format!("BPXSD - too many props (count {}, max is 256)", v)),
            Error::MissingProp(v) => f.write_str(&format!("BPXSD - missing property {}", v)),
            Error::Truncation(e) => f.write_str(&format!(
                "unexpected EOF while reading {}, are you sure the data is not truncated?",
                e
            )),
            Error::Corruption(e) => f.write_str(&format!("illegal bytes found ({})", e)),
            Error::Utf8(e) => f.write_str(&format!("utf8 decoding/encoding error in {}", e)),
            Error::Unsupported(e) => f.write_str(&format!("unsupported operation {}", e)),
            Error::Capacity(e) => f.write_str(&format!(
                "section capacity exceeded (found {} bytes, max is 2 pow 32 bytes)",
                e
            )),
            Error::Deflate(e) => f.write_str(&format!("deflate error ({})", e)),
            Error::Inflate(e) => f.write_str(&format!("inflate error ({})", e)),
            Error::Other(e) => f.write_str(&format!("{}", e))
        };
    }
}
