openstranded_map_tool/

parser.rs

// openstranded-map-tool — convert Stranded II .s2 maps to .osmap format
// Copyright (C) 2026  OpenStranded contributors
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

//! Binary parser for Stranded II `.s2` map files.
//!
//! **Authoritative reference:** `original-source/source/includes/e_save_map.bb`
//! — the actual Blitz3D save routine. The `.s2-map-format.md` doc has several
//! errors; the source is the source of truth.

use std::io::{Cursor, Read};

use crate::types::*;

/// Errors that can occur during `.s2` parsing.
#[derive(Debug)]
pub enum S2Error {
    Io(std::io::Error),
    InvalidHeader(String),
    UnexpectedEof,
    InvalidTrailer(String),
    UnsupportedFormat(String),
}

impl std::fmt::Display for S2Error {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            S2Error::Io(e) => write!(f, "I/O error: {e}"),
            S2Error::InvalidHeader(s) => write!(f, "invalid header: {s}"),
            S2Error::UnexpectedEof => write!(f, "unexpected end of file"),
            S2Error::InvalidTrailer(s) => write!(f, "invalid trailer: {s}"),
            S2Error::UnsupportedFormat(s) => write!(f, "unsupported format: {s}"),
        }
    }
}

impl std::error::Error for S2Error {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match self {
            S2Error::Io(e) => Some(e),
            _ => None,
        }
    }
}

impl From<std::io::Error> for S2Error {
    fn from(e: std::io::Error) -> Self {
        S2Error::Io(e)
    }
}

/// Specialized result type for `.s2` parsing.
pub type S2Result<T> = Result<T, S2Error>;

// ---------------------------------------------------------------------------
// Helper: reading primitives from a Cursor
// ---------------------------------------------------------------------------

fn read_u8(c: &mut Cursor<&[u8]>) -> S2Result<u8> {
    let mut buf = [0u8; 1];
    c.read_exact(&mut buf)?;
    Ok(buf[0])
}

fn read_u16_le(c: &mut Cursor<&[u8]>) -> S2Result<u16> {
    let mut buf = [0u8; 2];
    c.read_exact(&mut buf)?;
    Ok(u16::from_le_bytes(buf))
}

fn read_u32_le(c: &mut Cursor<&[u8]>) -> S2Result<u32> {
    let mut buf = [0u8; 4];
    c.read_exact(&mut buf)?;
    Ok(u32::from_le_bytes(buf))
}

fn read_f32_le(c: &mut Cursor<&[u8]>) -> S2Result<f32> {
    let mut buf = [0u8; 4];
    c.read_exact(&mut buf)?;
    Ok(f32::from_le_bytes(buf))
}

fn read_exact(c: &mut Cursor<&[u8]>, n: usize) -> S2Result<Vec<u8>> {
    let mut buf = vec![0u8; n];
    c.read_exact(&mut buf)?;
    Ok(buf)
}

/// Read a Blitz3D `WriteString`: u32 LE length prefix + data (Windows-1252).
/// Uses lossy UTF-8 conversion for non-UTF-8 bytes.
fn read_s2_string(c: &mut Cursor<&[u8]>) -> S2Result<String> {
    let len = read_u32_le(c)? as usize;
    if len == 0 {
        return Ok(String::new());
    }
    let bytes = read_exact(c, len)?;
    Ok(String::from_utf8_lossy(&bytes).into_owned())
}

/// Read a Blitz3D `WriteLine`: read until `\r\n`. Uses lossy UTF-8 conversion.
fn read_s2_line(c: &mut Cursor<&[u8]>) -> S2Result<String> {
    let mut bytes = Vec::new();
    loop {
        let b = read_u8(c)?;
        if b == b'\r' {
            let next = read_u8(c)?;
            if next == b'\n' {
                break;
            }
            bytes.push(b);
            bytes.push(next);
        } else {
            bytes.push(b);
        }
    }
    Ok(String::from_utf8_lossy(&bytes).into_owned())
}

// ---------------------------------------------------------------------------
// Main parser
// ---------------------------------------------------------------------------

/// Parse a complete `.s2` file from a byte slice.
pub fn parse_s2(data: &[u8]) -> S2Result<S2Map> {
    let mut c = Cursor::new(data);

    // ---- 1. Header — dynamic lines until "###\r\n" ----
    let header = parse_header(&mut c)?;

    // ---- 2. Minimap (96×72×3 = 20736 bytes, 24-bit RGB) ----
    let minimap = read_exact(&mut c, 20736)?;

    // ---- 3. Password header ----
    // From source: WriteByte(stream, pwkey) + WriteLine(stream, encodedpw$)
    let pw_key = read_u8(&mut c)?;
    let encoded_pw = read_s2_line(&mut c)?;

    // ---- 4. Environment variables ----
    let env_vars = parse_env_vars(&mut c)?;

    // ---- 5. Quickslots (10 × WriteString) ----
    let quickslots = parse_quickslots(&mut c)?;

    // ---- 6. Colormap ----
    let colormap_dim = read_u32_le(&mut c)?;
    let colormap_size = (colormap_dim * colormap_dim * 3) as usize;
    let colormap = read_exact(&mut c, colormap_size)?;

    // ---- 7. Heightmap ----
    let terrain_size = read_u32_le(&mut c)?;
    let height_count = ((terrain_size + 1) * (terrain_size + 1)) as usize;
    let mut heights = Vec::with_capacity(height_count);
    for _ in 0..height_count {
        heights.push(read_f32_le(&mut c)?);
    }

    // ---- 8. Grass layer (colormap_dim+1)² bytes, column-major ----
    let grass_dim = colormap_dim + 1;
    let grass_size = (grass_dim * grass_dim) as usize;
    let grass = read_exact(&mut c, grass_size)?;

    // ---- 9. Footer: entity sections + trailer ----
    let (objects, units, items, infos, states, extensions, trailer) = parse_footer(&mut c)?;

    // Detect password from encoded form
    let decoded_pw = decode_password(&encoded_pw, pw_key);

    Ok(S2Map {
        header,
        minimap,
        password: S2Password {
            key: pw_key,
            encoded: encoded_pw,
            decoded: decoded_pw,
        },
        env_vars,
        quickslots,
        colormap_dim,
        colormap,
        terrain_size,
        heights,
        grass,
        objects,
        units,
        items,
        infos,
        states,
        extensions,
        trailer,
    })
}

/// Simple XOR-based password decoder from the Blitz3D source's `code()` function.
fn decode_password(encoded: &str, key: u8) -> String {
    let bytes = encoded.as_bytes();
    let decoded: Vec<u8> = bytes.iter().map(|&b| b ^ key).collect();
    String::from_utf8_lossy(&decoded).into_owned()
}

// ---------------------------------------------------------------------------
// Header
// ---------------------------------------------------------------------------

fn parse_header(c: &mut Cursor<&[u8]>) -> S2Result<S2Header> {
    let mut lines: Vec<String> = Vec::new();
    loop {
        let line = read_s2_line(c)?;
        if line == "###" {
            break;
        }
        lines.push(line);
    }

    if lines.len() < 11 {
        return Err(S2Error::InvalidHeader(format!(
            "expected 11+ header lines before '###', got {}",
            lines.len()
        )));
    }

    // Line 0: "### Stranded II Mapfile ..."
    if !lines[0].starts_with("### Stranded II Mapfile") {
        return Err(S2Error::InvalidHeader(format!(
            "not a Stranded II map file: {:?}",
            lines[0]
        )));
    }

    // Lines 1-5 (indices 1-5)
    let version = lines.get(1).cloned().unwrap_or_default();
    let date = lines.get(2).cloned().unwrap_or_default();
    let time = lines.get(3).cloned().unwrap_or_default();
    let author = lines.get(4).cloned().unwrap_or_default();
    let map_type = lines.get(5).cloned().unwrap_or_default();

    // Lines 6-10: blank lines (or type_format for .map export)
    // Lines 6..10 may contain "001"-style format spec in .map files, but
    // in .s2 they should be blank. We ignore them.

    Ok(S2Header {
        version,
        date,
        time,
        author,
        map_type,
    })
}

// ---------------------------------------------------------------------------
// Environment variables
// ---------------------------------------------------------------------------
// Source order (e_save_map.bb lines 70-84):
//   WriteInt(day) → 4
//   WriteByte(hour) → 1
//   WriteByte(minute) → 1
//   WriteByte(freezetime) → 1
//   WriteString(skybox) → 4 + len
//   WriteByte(multiplayer) → 1
//   WriteByte(climate) → 1
//   WriteString(music) → 4 + len
//   WriteString(briefing) → 4 + len
//   WriteByte(fog_r) → 1
//   WriteByte(fog_g) → 1
//   WriteByte(fog_b) → 1
//   WriteByte(fog_mode) → 1
//   WriteByte(extra) → 1

fn parse_env_vars(c: &mut Cursor<&[u8]>) -> S2Result<S2EnvVars> {
    let day = read_u32_le(c)?;
    let hour = read_u8(c)?;
    let minute = read_u8(c)?;
    let freezetime = read_u8(c)?;
    let skybox = read_s2_string(c)?;
    let multiplayer = read_u8(c)?;
    let climate = read_u8(c)?;
    let music = read_s2_string(c)?;
    let briefing = read_s2_string(c)?;
    let f_r = read_u8(c)?;
    let f_g = read_u8(c)?;
    let f_b = read_u8(c)?;
    let f_mode = read_u8(c)?;
    let extra = read_u8(c)?;

    Ok(S2EnvVars {
        day,
        hour,
        minute,
        freezetime,
        skybox,
        multiplayer,
        climate,
        music,
        briefing,
        fog: [f_r, f_g, f_b, f_mode],
        extra,
    })
}

// ---------------------------------------------------------------------------
// Quickslots
// ---------------------------------------------------------------------------

fn parse_quickslots(c: &mut Cursor<&[u8]>) -> S2Result<Vec<String>> {
    let mut slots = Vec::with_capacity(10);
    for _ in 0..10 {
        slots.push(read_s2_string(c)?);
    }
    Ok(slots)
}

// ---------------------------------------------------------------------------
// Footer
// ---------------------------------------------------------------------------

fn parse_footer(
    c: &mut Cursor<&[u8]>,
) -> S2Result<(
    Vec<S2Object>,
    Vec<S2Unit>,
    Vec<S2Item>,
    Vec<S2Info>,
    Vec<S2State>,
    Vec<S2Extension>,
    S2Trailer,
)> {
    // 6 section counts (u32 each)
    let obj_count = read_u32_le(c)?;
    let unit_count = read_u32_le(c)?;
    let item_count = read_u32_le(c)?;
    let info_count = read_u32_le(c)?;
    let state_count = read_u32_le(c)?;
    let ext_count = read_u32_le(c)?;

    // Determine type format flags
    // tfX = 1 when count > 255, else 0
    let tf_object = obj_count > 255;
    let tf_unit = unit_count > 255;
    let tf_item = item_count > 255;

    let mut objects = Vec::with_capacity(obj_count as usize);
    for _ in 0..obj_count {
        objects.push(parse_object(c, tf_object)?);
    }

    let mut units = Vec::with_capacity(unit_count as usize);
    for _ in 0..unit_count {
        units.push(parse_unit(c, tf_unit)?);
    }

    let mut items = Vec::with_capacity(item_count as usize);
    for _ in 0..item_count {
        items.push(parse_item(c, tf_item)?);
    }

    let mut infos = Vec::with_capacity(info_count as usize);
    for _ in 0..info_count {
        infos.push(parse_info(c)?);
    }

    let mut states = Vec::with_capacity(state_count as usize);
    for _ in 0..state_count {
        states.push(parse_state(c)?);
    }

    let mut extensions = Vec::with_capacity(ext_count as usize);
    for _ in 0..ext_count {
        extensions.push(parse_extension(c)?);
    }

    // Trailer: WriteLine("") + WriteLine("### EOF Map File") + WriteLine("www.unrealsoftware.de")
    let blank = read_s2_line(c)?;
    let eof_marker = read_s2_line(c)?;
    let url = read_s2_line(c)?;

    if !eof_marker.is_empty() && eof_marker != "### EOF Map File" {
        return Err(S2Error::InvalidTrailer(format!(
            "expected '### EOF Map File', got {:?}",
            eof_marker
        )));
    }
    if !url.is_empty() && url != "www.unrealsoftware.de" {
        return Err(S2Error::InvalidTrailer(format!(
            "expected 'www.unrealsoftware.de', got {:?}",
            url
        )));
    }

    let trailer = S2Trailer {
        blank,
        eof_marker,
        url,
    };

    Ok((objects, units, items, infos, states, extensions, trailer))
}

// ---------------------------------------------------------------------------
// Entity parsers (all from e_save_map.bb)
// ---------------------------------------------------------------------------

/// Object record (e_save_map.bb lines 137-148):
///   WriteInt(id), If tf: WriteShort(typ)/WriteByte(typ),
///   WriteFloat(x), WriteFloat(z), WriteFloat(yaw),
///   WriteFloat(health), WriteFloat(health_max), WriteInt(daytimer)
fn parse_object(c: &mut Cursor<&[u8]>, tf: bool) -> S2Result<S2Object> {
    let id = read_u32_le(c)?;
    let typ = if tf {
        read_u16_le(c)? as u32
    } else {
        read_u8(c)? as u32
    };
    let x = read_f32_le(c)?;
    let z = read_f32_le(c)?;
    let yaw = read_f32_le(c)?;
    let health = read_f32_le(c)?;
    let health_max = read_f32_le(c)?;
    let day_timer = read_u32_le(c)?;
    Ok(S2Object {
        id,
        typ,
        x,
        z,
        yaw,
        health,
        health_max,
        day_timer,
    })
}

/// Unit record (e_save_map.bb lines 166-182):
///   WriteInt(id), If tf: WriteShort(typ)/WriteByte(typ),
///   WriteFloat(x), WriteFloat(y), WriteFloat(z), WriteFloat(yaw),
///   WriteFloat(health), WriteFloat(health_max),
///   WriteFloat(hunger), WriteFloat(thirst), WriteFloat(exhaustion),
///   WriteFloat(ai_cx), WriteFloat(ai_cz)
fn parse_unit(c: &mut Cursor<&[u8]>, tf: bool) -> S2Result<S2Unit> {
    let id = read_u32_le(c)?;
    let typ = if tf {
        read_u16_le(c)? as u32
    } else {
        read_u8(c)? as u32
    };
    let x = read_f32_le(c)?;
    let y = read_f32_le(c)?;
    let z = read_f32_le(c)?;
    let yaw = read_f32_le(c)?;
    let health = read_f32_le(c)?;
    let health_max = read_f32_le(c)?;
    let hunger = read_f32_le(c)?;
    let thirst = read_f32_le(c)?;
    let exhaustion = read_f32_le(c)?;
    let ai_center_x = read_f32_le(c)?;
    let ai_center_z = read_f32_le(c)?;

    Ok(S2Unit {
        id,
        typ,
        x,
        y,
        z,
        yaw,
        health,
        health_max,
        hunger,
        thirst,
        exhaustion,
        ai_center_x,
        ai_center_z,
    })
}

/// Item record (e_save_map.bb lines 192-207):
///   WriteInt(id), If tf: WriteShort(typ)/WriteByte(typ),
///   WriteFloat(x), WriteFloat(y), WriteFloat(z), WriteFloat(yaw),
///   WriteFloat(health), WriteInt(count),
///   WriteByte(parent_class), WriteByte(parent_mode), WriteInt(parent_id)
fn parse_item(c: &mut Cursor<&[u8]>, tf: bool) -> S2Result<S2Item> {
    let id = read_u32_le(c)?;
    let typ = if tf {
        read_u16_le(c)? as u32
    } else {
        read_u8(c)? as u32
    };
    let x = read_f32_le(c)?;
    let y = read_f32_le(c)?;
    let z = read_f32_le(c)?;
    let yaw = read_f32_le(c)?;
    let health = read_f32_le(c)?;
    let count = read_u32_le(c)?;
    let parent_class = read_u8(c)?;
    let parent_mode = read_u8(c)?;
    let parent_id = read_u32_le(c)?;
    Ok(S2Item {
        id,
        typ,
        x,
        y,
        z,
        yaw,
        health,
        count,
        parent_class,
        parent_mode,
        parent_id,
    })
}

/// Info record (e_save_map.bb lines 243-251):
///   WriteInt(id), WriteByte(typ),
///   WriteFloat(x), WriteFloat(y), WriteFloat(z),
///   WriteFloat(pitch), WriteFloat(yaw),
///   WriteString(vars)
fn parse_info(c: &mut Cursor<&[u8]>) -> S2Result<S2Info> {
    let id = read_u32_le(c)?;
    let typ = read_u8(c)?;
    let x = read_f32_le(c)?;
    let y = read_f32_le(c)?;
    let z = read_f32_le(c)?;
    let pitch = read_f32_le(c)?;
    let yaw = read_f32_le(c)?;
    let vars = read_s2_string(c)?;
    Ok(S2Info {
        id,
        typ,
        x,
        y,
        z,
        pitch,
        yaw,
        vars,
    })
}

/// State record (e_save_map.bb lines 260-272):
///   WriteByte(typ), WriteByte(parent_class), WriteInt(parent_id),
///   WriteFloat(x), WriteFloat(y), WriteFloat(z),
///   WriteFloat(fx), WriteFloat(fy), WriteFloat(fz),
///   WriteInt(value), WriteFloat(value_f), WriteString(value_s)
fn parse_state(c: &mut Cursor<&[u8]>) -> S2Result<S2State> {
    let typ = read_u8(c)? as u32;
    let parent_class = read_u8(c)? as u32;
    let parent_id = read_u32_le(c)?;
    let x = read_f32_le(c)?;
    let y = read_f32_le(c)?;
    let z = read_f32_le(c)?;
    let fx = read_f32_le(c)?;
    let fy = read_f32_le(c)?;
    let fz = read_f32_le(c)?;
    let value = read_u32_le(c)?;
    let value_f = read_f32_le(c)?;
    let value_s = read_s2_string(c)?;
    Ok(S2State {
        typ,
        parent_class,
        parent_id,
        x,
        y,
        z,
        fx,
        fy,
        fz,
        value,
        value_f,
        value_s,
    })
}

/// Extension record (e_save_map.bb lines 314-327):
///   WriteByte(typ), WriteByte(parent_class), WriteInt(parent_id),
///   WriteInt(mode),
///   If mode=0: WriteString("") Else WriteString(key),
///   WriteString(value), WriteString(stuff)
fn parse_extension(c: &mut Cursor<&[u8]>) -> S2Result<S2Extension> {
    let typ = read_u8(c)?;
    let parent_class = read_u8(c)?;
    let parent_id = read_u32_le(c)?;
    let mode = read_u32_le(c)?;
    let key = if mode == 0 {
        // Script keys not saved (mode=0)
        let _empty = read_s2_string(c)?;
        String::new()
    } else {
        read_s2_string(c)?
    };
    let value = read_s2_string(c)?;
    let stuff = read_s2_string(c)?;
    Ok(S2Extension {
        typ,
        parent_class,
        parent_id,
        mode,
        key,
        value,
        stuff,
    })
}

// ---------------------------------------------------------------------------
// Utility
// ---------------------------------------------------------------------------

/// Load a `.s2` file from disk and parse it.
pub fn parse_s2_file(path: impl AsRef<std::path::Path>) -> S2Result<S2Map> {
    let data = std::fs::read(path.as_ref()).map_err(S2Error::Io)?;
    parse_s2(&data)
}

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

    #[test]
    fn test_read_s2_string_empty() {
        let data: &[u8] = &[0, 0, 0, 0];
        let mut c = Cursor::new(data);
        let s = read_s2_string(&mut c).unwrap();
        assert_eq!(s, "");
        assert_eq!(c.position(), 4);
    }

    #[test]
    fn test_read_s2_string_hello() {
        let data: &[u8] = &[5, 0, 0, 0, b'H', b'e', b'l', b'l', b'o'];
        let mut c = Cursor::new(data);
        let s = read_s2_string(&mut c).unwrap();
        assert_eq!(s, "Hello");
    }

    #[test]
    fn test_parse_quickslots() {
        let mut data = Vec::new();
        for _ in 0..10 {
            data.extend_from_slice(&[1, 0, 0, 0, b'0']);
        }
        let mut c = Cursor::new(data.as_slice());
        let slots = parse_quickslots(&mut c).unwrap();
        assert_eq!(slots.len(), 10);
        assert!(slots.iter().all(|s| s == "0"));
    }

    #[test]
    fn test_decode_password_empty() {
        let pw = decode_password("", 0);
        assert_eq!(pw, "");
    }

    #[test]
    fn test_decode_password_xor() {
        // "123":
        //   '1' (0x31) ^ 50 = 0x31 ^ 0x32 = 0x03
        //   '2' (0x32) ^ 50 = 0x32 ^ 0x32 = 0x00
        //   '3' (0x33) ^ 50 = 0x33 ^ 0x32 = 0x01
        let encoded = "\x03\x00\x01";
        let pw = decode_password(encoded, 50);
        assert_eq!(pw, "123");
    }

    /// Build a minimal valid .s2 file for testing.
    /// 16×16 terrain, black colormap, no entities, no password, lasttime extension.
    fn build_minimal_s2() -> Vec<u8> {
        let mut buf = Vec::new();

        // 1. Header (variable-sized, terminated by "###\r\n")
        // NOTE: © is single byte \xa9 (Windows-1252), not UTF-8 \xc2\xa9
        buf.extend_from_slice(b"### Stranded II Mapfile \xa9by Unreal Software 2004-2007\r\n");
        buf.extend_from_slice(b"1.0.0.1\r\n");
        buf.extend_from_slice(b"10 Jul 2026\r\n");
        buf.extend_from_slice(b"18:10:56\r\n");
        buf.extend_from_slice(b"default\r\n");
        buf.extend_from_slice(b"map\r\n");
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"###\r\n");

        // 2. Minimap (20736 bytes of zeros)
        buf.extend(std::iter::repeat(0u8).take(20736));

        // 3. Password header: key=0, empty password → WriteByte(0) + WriteLine("")
        buf.push(0); // pwkey
        buf.extend_from_slice(b"\r\n"); // WriteLine("")

        // 4. Env vars
        buf.extend_from_slice(&1u32.to_le_bytes()); // day
        buf.push(9); // hour
        buf.push(0); // minute
        buf.push(3); // freezetime
        buf.extend_from_slice(&3u32.to_le_bytes()); // skybox "sky"
        buf.extend_from_slice(b"sky");
        buf.push(0); // multiplayer
        buf.push(0); // climate
        let music = b"amb_jungle.mp3";
        buf.extend_from_slice(&(music.len() as u32).to_le_bytes());
        buf.extend_from_slice(music);
        buf.extend_from_slice(&0u32.to_le_bytes()); // briefing (empty)
        buf.extend_from_slice(&[205, 210, 245, 0]); // fog
        buf.push(0); // extra

        // 5. Quickslots
        for _ in 0..10 {
            buf.extend_from_slice(&[1, 0, 0, 0, b'0']);
        }

        // 6. Colormap: dim=128, all zeros
        buf.extend_from_slice(&128u32.to_le_bytes());
        buf.extend(std::iter::repeat(0u8).take(128 * 128 * 3));

        // 7. Heightmap: size=16, 289 f32 values (0.447)
        buf.extend_from_slice(&16u32.to_le_bytes());
        for _ in 0..289 {
            buf.extend_from_slice(&0.447_f32.to_le_bytes());
        }

        // 8. Grass: (128+1)*(128+1) = 16641 bytes of zeros
        buf.extend(std::iter::repeat(0u8).take(16641));

        // 9. Footer: 0 entities, 1 extension (lasttime)
        buf.extend_from_slice(&0u32.to_le_bytes()); // objects
        buf.extend_from_slice(&0u32.to_le_bytes()); // units
        buf.extend_from_slice(&0u32.to_le_bytes()); // items
        buf.extend_from_slice(&0u32.to_le_bytes()); // infos
        buf.extend_from_slice(&0u32.to_le_bytes()); // states
        buf.extend_from_slice(&1u32.to_le_bytes()); // extensions

        // Extension: lasttime (mode=6)
        buf.push(0); // typ
        buf.push(0); // parent_class
        buf.extend_from_slice(&0u32.to_le_bytes()); // parent_id
        buf.extend_from_slice(&6u32.to_le_bytes()); // mode
        // mode=6, so key is saved
        buf.extend_from_slice(&8u32.to_le_bytes()); // key len
        buf.extend_from_slice(b"lasttime");
        buf.extend_from_slice(&0u32.to_le_bytes()); // value len (empty)
        buf.extend_from_slice(&5u32.to_le_bytes()); // stuff len
        buf.extend_from_slice(b"1,9,2"); // stuff

        // Trailer
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"### EOF Map File\r\n");
        buf.extend_from_slice(b"www.unrealsoftware.de\r\n");

        buf
    }

    #[test]
    fn test_parse_minimal_s2() {
        let data = build_minimal_s2();
        let result = parse_s2(&data);
        assert!(result.is_ok(), "parse failed: {:?}", result.err());
        let map = result.unwrap();
        assert_eq!(map.header.version, "1.0.0.1");
        assert_eq!(map.terrain_size, 16);
        assert!(map.objects.is_empty());
        assert!(map.units.is_empty());
        assert!(map.items.is_empty());
        assert!(map.infos.is_empty());
        assert!(map.states.is_empty());
        assert_eq!(map.extensions.len(), 1);
        assert_eq!(map.extensions[0].key, "lasttime");
    }

    #[test]
    fn test_parse_minimal_s2_with_password() {
        let mut buf = Vec::new();

        // Same header
        buf.extend_from_slice(b"### Stranded II Mapfile \xa9by Unreal Software 2004-2007\r\n");
        buf.extend_from_slice(b"1.0.0.1\r\n");
        buf.extend_from_slice(b"10 Jul 2026\r\n");
        buf.extend_from_slice(b"18:10:56\r\n");
        buf.extend_from_slice(b"default\r\n");
        buf.extend_from_slice(b"map\r\n");
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"###\r\n");

        // Minimap
        buf.extend(std::iter::repeat(0u8).take(20736));

        // Password: key=50, "123" XOR 50:
        //   '1'(0x31)^50 = 0x03, '2'(0x32)^50 = 0x00, '3'(0x33)^50 = 0x01
        buf.push(50); // key
        buf.extend_from_slice(b"\x03\x00\x01\r\n"); // WriteLine with encoded pw + \r\n

        // Rest same as minimal
        buf.extend_from_slice(&1u32.to_le_bytes()); // day
        buf.push(9);
        buf.push(0);
        buf.push(3);
        buf.extend_from_slice(&3u32.to_le_bytes());
        buf.extend_from_slice(b"sky");
        buf.push(0);
        buf.push(0);
        let music = b"amb_jungle.mp3";
        buf.extend_from_slice(&(music.len() as u32).to_le_bytes());
        buf.extend_from_slice(music);
        buf.extend_from_slice(&0u32.to_le_bytes());
        buf.extend_from_slice(&[205, 210, 245, 0]);
        buf.push(0);
        for _ in 0..10 {
            buf.extend_from_slice(&[1, 0, 0, 0, b'0']);
        }
        buf.extend_from_slice(&128u32.to_le_bytes());
        buf.extend(std::iter::repeat(0u8).take(128 * 128 * 3));
        buf.extend_from_slice(&16u32.to_le_bytes());
        for _ in 0..289 {
            buf.extend_from_slice(&0.447_f32.to_le_bytes());
        }
        buf.extend(std::iter::repeat(0u8).take(16641));
        buf.extend_from_slice(&0u32.to_le_bytes());
        buf.extend_from_slice(&0u32.to_le_bytes());
        buf.extend_from_slice(&0u32.to_le_bytes());
        buf.extend_from_slice(&0u32.to_le_bytes());
        buf.extend_from_slice(&0u32.to_le_bytes());
        buf.extend_from_slice(&1u32.to_le_bytes());
        buf.push(0);
        buf.push(0);
        buf.extend_from_slice(&0u32.to_le_bytes());
        buf.extend_from_slice(&6u32.to_le_bytes());
        buf.extend_from_slice(&8u32.to_le_bytes());
        buf.extend_from_slice(b"lasttime");
        buf.extend_from_slice(&0u32.to_le_bytes());
        buf.extend_from_slice(&5u32.to_le_bytes());
        buf.extend_from_slice(b"1,9,2");
        buf.extend_from_slice(b"\r\n");
        buf.extend_from_slice(b"### EOF Map File\r\n");
        buf.extend_from_slice(b"www.unrealsoftware.de\r\n");

        let result = parse_s2(&buf);
        assert!(result.is_ok(), "parse failed: {:?}", result.err());
        let map = result.unwrap();
        assert_eq!(map.password.key, 50);
        assert_eq!(map.password.decoded, "123");
    }
}