use std::path::PathBuf;
use std::sync::Arc;

pub struct SourceFile {
    pub id: usize,
    pub path: PathBuf,
    pub source: Arc<str>,
}

pub struct FileManager {
    files: Vec<SourceFile>,
}

impl FileManager {
    pub fn new() -> Self {
        Self { files: Vec::new() }
    }

    pub fn add(&mut self, path: PathBuf, source: String) -> usize {
        let id = self.files.len();
        self.files.push(SourceFile {
            id,
            path,
            source: Arc::from(source),
        });
        id
    }

    pub fn get_file(&self, id: usize) -> Option<&SourceFile> {
        self.files.get(id)
    }

    pub fn get_path(&self, id: usize) -> Option<PathBuf> {
        self.files.get(id).map(|f| f.path.clone())
    }

    pub fn lookup_pos(&self, file_id: usize, pos: u32) -> (usize, usize) {
        let file = if let Some(f) = self.files.get(file_id) {
            f
        } else {
            return (0, 0);
        };

        let mut line = 1;
        let mut col = 1;
        for (i, c) in file.source.char_indices() {
            if i as u32 == pos {
                break;
            }
            if c == '\n' {
                line += 1;
                col = 1;
            } else {
                col += 1;
            }
        }
        (line, col)
    }
}