scriptmark 0.2.0

use std::collections::HashMap;
use std::path::Path;

/// Load a roster CSV mapping student IDs to names.
///
/// Expected format: `name,_,student_id` (header row skipped).
/// Handles UTF-8 BOM.
pub fn load_roster(path: &Path) -> Result<HashMap<String, String>, RosterError> {
	let content =
		std::fs::read_to_string(path).map_err(|e| RosterError::IoError(path.to_path_buf(), e))?;

	// Strip UTF-8 BOM if present
	let content = content.strip_prefix('\u{feff}').unwrap_or(&content);

	let mut reader = csv::ReaderBuilder::new()
		.has_headers(true)
		.flexible(true)
		.from_reader(content.as_bytes());

	let mut roster = HashMap::new();

	for result in reader.records() {
		let record = result.map_err(|e| RosterError::CsvError(path.to_path_buf(), e))?;

		// Format: name, _, student_id (or name, student_id)
		let name = record.get(0).unwrap_or("").trim().to_string();
		let student_id = if record.len() >= 3 {
			record.get(2).unwrap_or("").trim().to_string()
		} else if record.len() >= 2 {
			record.get(1).unwrap_or("").trim().to_string()
		} else {
			continue;
		};

		if !student_id.is_empty() {
			roster.insert(student_id, name);
		}
	}

	Ok(roster)
}

#[derive(Debug, thiserror::Error)]
pub enum RosterError {
	#[error("IO error reading {0}: {1}")]
	IoError(std::path::PathBuf, std::io::Error),
	#[error("CSV parse error in {0}: {1}")]
	CsvError(std::path::PathBuf, csv::Error),
}

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

	#[test]
	fn test_load_roster() {
		let dir = tempfile::tempdir().unwrap();
		let path = dir.path().join("roster.csv");
		std::fs::write(
			&path,
			"name,class,student_id\nAlice,A,alice123\nBob,B,bob456\n",
		)
		.unwrap();

		let roster = load_roster(&path).unwrap();
		assert_eq!(roster.len(), 2);
		assert_eq!(roster["alice123"], "Alice");
		assert_eq!(roster["bob456"], "Bob");
	}

	#[test]
	fn test_load_roster_with_bom() {
		let dir = tempfile::tempdir().unwrap();
		let path = dir.path().join("roster.csv");
		std::fs::write(&path, "\u{feff}name,class,student_id\nAlice,A,alice123\n").unwrap();

		let roster = load_roster(&path).unwrap();
		assert_eq!(roster["alice123"], "Alice");
	}
}