hadris-iso 2.0.0

use hadris_fixed::FixedBytes;

#[cfg(feature = "alloc")]
use crate::joliet::JolietLevel;

#[cfg(feature = "write")]
use crate::types::{Charset, CharsetD, CharsetD1};

/// The type of directory entry, indicating the ISO interchange level and features
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum EntryType {
    /// The `Level1` variant.
    Level1 {
        /// The `supports_lowercase` field.
        supports_lowercase: bool,
        /// The `supports_rrip` field.
        supports_rrip: bool,
    },
    /// The `Level2` variant.
    Level2 {
        /// The `supports_lowercase` field.
        supports_lowercase: bool,
        /// The `supports_rrip` field.
        supports_rrip: bool,
    },
    /// The `Level3` variant.
    Level3 {
        /// The `supports_lowercase` field.
        supports_lowercase: bool,
        /// The `supports_rrip` field.
        supports_rrip: bool,
    },
    #[cfg(feature = "alloc")]
    /// The `Joliet` variant.
    Joliet {
        /// The `level` field.
        level: JolietLevel,
        /// The `supports_rrip` field.
        supports_rrip: bool,
    },
}

impl Default for EntryType {
    fn default() -> Self {
        Self::Level1 {
            supports_lowercase: false,
            supports_rrip: false,
        }
    }
}

impl EntryType {
    // Usefulness coefficient:
    // bits 0-3 = base level (lowercase = 4,5,6 Joliet = level 12, 13, 14)
    // bit 4 = rrip
    /// Performs the `supports_rrip` operation.
    pub fn supports_rrip(&self) -> bool {
        match self {
            Self::Level1 { supports_rrip, .. } => *supports_rrip,
            Self::Level2 { supports_rrip, .. } => *supports_rrip,
            Self::Level3 { supports_rrip, .. } => *supports_rrip,
            #[cfg(feature = "alloc")]
            Self::Joliet { supports_rrip, .. } => *supports_rrip,
        }
    }

    // Usefulness coefficient:
    // bits 0-3 = base level (lowercase = 4,5,6 Joliet = level 12, 13, 14)
    // bit 4 = rrip
    fn usefulness(self) -> u8 {
        match self {
            Self::Level1 {
                supports_lowercase,
                supports_rrip,
            } => (supports_lowercase as u8) << 2 | (supports_rrip as u8) << 4,
            Self::Level2 {
                supports_lowercase,
                supports_rrip,
            } => 0x01 | (supports_lowercase as u8) << 2 | (supports_rrip as u8) << 4,
            Self::Level3 {
                supports_lowercase,
                supports_rrip,
            } => 0x02 | (supports_lowercase as u8) << 2 | (supports_rrip as u8) << 4,
            #[cfg(feature = "alloc")]
            Self::Joliet {
                level,
                supports_rrip,
            } => (level as u8 + 11) | (supports_rrip as u8) << 4,
        }
    }
}

impl Ord for EntryType {
    fn cmp(&self, other: &Self) -> core::cmp::Ordering {
        self.usefulness().cmp(&other.usefulness())
    }
}

impl PartialOrd for EntryType {
    fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
        Some(self.cmp(other))
    }
}

#[cfg(feature = "alloc")]
impl From<JolietLevel> for EntryType {
    fn from(value: JolietLevel) -> Self {
        Self::Joliet {
            level: value,
            supports_rrip: false,
        }
    }
}

/// Type alias for FilenameL1.
pub type FilenameL1 = FixedBytes<14>;
/// Type alias for FilenameL2.
pub type FilenameL2 = FixedBytes<32>;
/// Type alias for FilenameL3.
pub type FilenameL3 = FixedBytes<207>;

#[cfg(feature = "write")]
/// Identifies a ConvertedName value.
pub enum ConvertedName {
    /// The `Level1` variant.
    Level1(FilenameL1),
    /// The `Level2` variant.
    Level2(FilenameL2),
    /// The `Level3` variant.
    Level3(FilenameL3),
    /// The `Joliet` variant.
    Joliet(FixedBytes<207>),
}

#[cfg(feature = "write")]
impl ConvertedName {
    /// Performs the `as_bytes` operation.
    pub fn as_bytes(&self) -> &[u8] {
        match self {
            Self::Level1(name) => name.as_bytes(),
            Self::Level2(name) => name.as_bytes(),
            Self::Level3(name) => name.as_bytes(),
            Self::Joliet(name) => name.as_bytes(),
        }
    }
}

#[cfg(feature = "write")]
impl EntryType {
    /// Performs the `convert_name` operation.
    pub fn convert_name(self, name: &str) -> ConvertedName {
        match self {
            Self::Level1 {
                supports_lowercase, ..
            } => ConvertedName::Level1(convert_l1(name, supports_lowercase)),
            Self::Level2 {
                supports_lowercase, ..
            } => ConvertedName::Level2(convert_l2(name, supports_lowercase)),
            Self::Level3 {
                supports_lowercase, ..
            } => ConvertedName::Level3(convert_l3(name, supports_lowercase)),
            Self::Joliet { level, .. } => match level {
                // All Joliet levels use UTF-16 BE encoding
                JolietLevel::Level1 | JolietLevel::Level2 | JolietLevel::Level3 => {
                    ConvertedName::Joliet(convert_joliet3(name))
                }
            },
        }
    }

    /// Converts a directory name without a file extension or version suffix.
    pub fn convert_directory_name(self, name: &str) -> ConvertedName {
        fn primary<const N: usize>(
            name: &str,
            max: usize,
            supports_lowercase: bool,
        ) -> FixedBytes<N> {
            let mut converted = FixedBytes::empty();
            let end = name
                .char_indices()
                .map(|(offset, _)| offset)
                .take_while(|offset| *offset <= max)
                .last()
                .unwrap_or(0);
            let end = if name.len() <= max { name.len() } else { end };
            let range = converted.push_slice(&name.as_bytes()[..end]);
            let bytes = converted.as_bytes_mut()[range].iter_mut();
            if supports_lowercase {
                CharsetD1::substitute_invalid(bytes);
            } else {
                CharsetD::substitute_invalid(bytes);
            }
            converted
        }

        match self {
            Self::Level1 {
                supports_lowercase, ..
            } => ConvertedName::Level1(primary(name, 8, supports_lowercase)),
            Self::Level2 {
                supports_lowercase, ..
            } => ConvertedName::Level2(primary(name, 31, supports_lowercase)),
            Self::Level3 {
                supports_lowercase, ..
            } => ConvertedName::Level3(primary(name, 31, supports_lowercase)),
            Self::Joliet { .. } => ConvertedName::Joliet(convert_joliet3(name)),
        }
    }
}

#[cfg(feature = "write")]
/// Performs the `convert_l1` operation.
pub fn convert_l1(name: &str, supports_lowercase: bool) -> FixedBytes<14> {
    let mut l1 = FixedBytes::empty();
    let name_bytes = name.as_bytes();
    match name.find('.') {
        Some(index) => {
            // We copy the basename, at most 8 bytes
            let basename = l1.push_slice(&name_bytes[0..index.min(8)]);
            let basename = l1.as_bytes_mut()[basename].iter_mut();
            if supports_lowercase {
                CharsetD1::substitute_invalid(basename);
            } else {
                CharsetD::substitute_invalid(basename);
            }
            // Extension length excluding the dot character
            let ext_len = (name.len() - index - 1).min(3);
            l1.push_byte(b'.');
            let ext = l1.push_slice(&name_bytes[index + 1..(index + 1 + ext_len).min(name.len())]);
            let ext = l1.as_bytes_mut()[ext].iter_mut();
            if supports_lowercase {
                CharsetD1::substitute_invalid(ext);
            } else {
                CharsetD::substitute_invalid(ext);
            }
        }
        None => {
            let len = name.len().min(8);
            let basename = l1.push_slice(&name_bytes[0..len]);
            let basename = l1.as_bytes_mut()[basename].iter_mut();
            if supports_lowercase {
                CharsetD1::substitute_invalid(basename);
            } else {
                CharsetD::substitute_invalid(basename);
            }
        }
    }
    l1.push_slice(b";1");
    l1
}

#[cfg(feature = "write")]
/// Performs the `convert_l2` operation.
pub fn convert_l2(name: &str, supports_lowercase: bool) -> FilenameL2 {
    let mut l2 = FilenameL2::empty();
    let name_bytes = name.as_bytes();
    // Max: 30 bytes for name (reserve 2 for ";1")
    const MAX_NAME_LEN: usize = 30;

    match name.find('.') {
        Some(index) => {
            let basename_end = index.min(MAX_NAME_LEN);
            let basename = l2.push_slice(&name_bytes[0..basename_end]);
            let basename = l2.as_bytes_mut()[basename].iter_mut();
            if supports_lowercase {
                CharsetD1::substitute_invalid(basename);
            } else {
                CharsetD::substitute_invalid(basename);
            }

            // Calculate remaining space for extension (subtract basename length and 1 for dot)
            let remaining = MAX_NAME_LEN.saturating_sub(basename_end + 1);
            if remaining > 0 {
                l2.push_byte(b'.');
                let ext_end = (index + 1 + remaining).min(name.len());
                let ext = l2.push_slice(&name_bytes[index + 1..ext_end]);
                let ext = l2.as_bytes_mut()[ext].iter_mut();
                if supports_lowercase {
                    CharsetD1::substitute_invalid(ext);
                } else {
                    CharsetD::substitute_invalid(ext);
                }
            }
        }
        None => {
            let len = name.len().min(MAX_NAME_LEN);
            let basename = l2.push_slice(&name_bytes[0..len]);
            let basename = l2.as_bytes_mut()[basename].iter_mut();
            if supports_lowercase {
                CharsetD1::substitute_invalid(basename);
            } else {
                CharsetD::substitute_invalid(basename);
            }
        }
    }
    l2.push_slice(b";1");
    l2
}

#[cfg(feature = "write")]
/// Performs the `convert_l3` operation.
pub fn convert_l3(name: &str, supports_lowercase: bool) -> FilenameL3 {
    let mut l3 = FilenameL3::empty();
    let name_bytes = name.as_bytes();
    // Max: 207 bytes for name (no version suffix in L3)
    const MAX_NAME_LEN: usize = 207;

    match name.find('.') {
        Some(index) => {
            let basename_end = index.min(MAX_NAME_LEN);
            let basename = l3.push_slice(&name_bytes[0..basename_end]);
            let basename = l3.as_bytes_mut()[basename].iter_mut();
            if supports_lowercase {
                CharsetD1::substitute_invalid(basename);
            } else {
                CharsetD::substitute_invalid(basename);
            }

            // Calculate remaining space for extension (subtract basename length and 1 for dot)
            let remaining = MAX_NAME_LEN.saturating_sub(basename_end + 1);
            if remaining > 0 {
                l3.push_byte(b'.');
                let ext_end = (index + 1 + remaining).min(name.len());
                let ext = l3.push_slice(&name_bytes[index + 1..ext_end]);
                let ext = l3.as_bytes_mut()[ext].iter_mut();
                if supports_lowercase {
                    CharsetD1::substitute_invalid(ext);
                } else {
                    CharsetD::substitute_invalid(ext);
                }
            }
        }
        None => {
            let len = name.len().min(MAX_NAME_LEN);
            let basename = l3.push_slice(&name_bytes[0..len]);
            let basename = l3.as_bytes_mut()[basename].iter_mut();
            if supports_lowercase {
                CharsetD1::substitute_invalid(basename);
            } else {
                CharsetD::substitute_invalid(basename);
            }
        }
    }
    l3
}

/// Maximum number of characters in a Joliet file identifier.
///
/// The Joliet specification limits a file identifier to 64 UCS-2 characters.
/// (A 255-byte directory record could physically hold up to 103, but 64 is the
/// conformant limit produced by default by reference tools.)
#[cfg(feature = "write")]
pub const JOLIET_MAX_NAME_CHARS: usize = 64;

#[cfg(feature = "write")]
/// Encode `name` as a big-endian UCS-2 Joliet file identifier.
///
/// Joliet identifiers are UCS-2 (Basic Multilingual Plane only), not UTF-16:
/// a character outside the BMP cannot be represented as a single UCS-2 code
/// unit, so it is substituted with `_` rather than emitting a surrogate pair
/// into the field. The identifier is limited to [`JOLIET_MAX_NAME_CHARS`]
/// characters; longer names are truncated.
pub fn convert_joliet3(name: &str) -> FixedBytes<207> {
    let mut j1 = FixedBytes::empty();
    for c in name.chars().take(JOLIET_MAX_NAME_CHARS) {
        let unit = if (c as u32) <= 0xFFFF {
            c as u16
        } else {
            b'_' as u16
        };
        j1.push_slice(&unit.to_be_bytes());
    }

    j1
}

#[cfg(all(test, feature = "write", feature = "alloc"))]
mod joliet_tests {
    use super::*;
    use crate::joliet::decode_joliet_name;

    #[test]
    fn joliet_name_is_truncated_to_the_conformant_limit() {
        let long = "a".repeat(200);
        let encoded = convert_joliet3(&long);
        // Two bytes per UCS-2 unit, capped at 64 characters.
        assert_eq!(encoded.as_bytes().len(), JOLIET_MAX_NAME_CHARS * 2);
        assert_eq!(decode_joliet_name(encoded.as_bytes()).chars().count(), 64);
    }

    #[test]
    fn joliet_substitutes_non_bmp_instead_of_emitting_surrogates() {
        // U+1F600 GRINNING FACE is outside the BMP and cannot be UCS-2 encoded.
        let encoded = convert_joliet3("a\u{1F600}b.txt");
        let decoded = decode_joliet_name(encoded.as_bytes());
        assert_eq!(decoded, "a_b.txt");
        // No byte pair may fall in the UTF-16 surrogate range 0xD800..=0xDFFF.
        for pair in encoded.as_bytes().chunks_exact(2) {
            let unit = u16::from_be_bytes([pair[0], pair[1]]);
            assert!(
                !(0xD800..=0xDFFF).contains(&unit),
                "surrogate leaked into UCS-2"
            );
        }
    }

    #[test]
    fn joliet_preserves_bmp_unicode() {
        let encoded = convert_joliet3("日本語.txt");
        assert_eq!(decode_joliet_name(encoded.as_bytes()), "日本語.txt");
    }
}