use super::*;


pub struct DirectoryListing {
    children: Vec<DirectoryChild>,
    length: u32,
    selected: Option<u32>,
    name_buffer: CircularPathBuffer,
}

impl DirectoryListing {
    pub fn from_path(path: &BedrockFilePath) -> Option<Self> {
        macro_rules! unres {
            ($result:expr) => { match $result { Ok(v) => v, Err(_) => continue} };
        }
        macro_rules! unopt {
            ($option:expr) => { match $option { Some(v) => v, None => continue} };
        }

        let mut children = Vec::new();
        let dir_listing = std::fs::read_dir(path.as_path()).ok()?;
        for (i, entry_result) in dir_listing.enumerate() {
            // Firebreak to prevent emulator from consuming an absurd amount
            // of memory when opening too large of a directory.
            if i == (u16::MAX as usize) {
                break;
            }

            let entry = unres!(entry_result);
            let entry_path = unopt!(BedrockFilePath::from_path(&entry.path(), path.base()));
            if entry_path.filename_is_dot_prefixed() {
                continue;
            }
            let metadata = unres!(std::fs::metadata(&entry.path()));
            let entry_type =
                if metadata.is_file() {
                    EntryType::File
                } else if metadata.is_dir() {
                    EntryType::Directory
                } else {
                    continue;
                };

            let child = DirectoryChild { path: entry_path, entry_type };
            children.push(child);
        }

        children.sort();
        let length = u32::try_from(children.len()).ok()?;
        let selected = None;
        let name_buffer = CircularPathBuffer::new();
        Some( Self { children, length, selected, name_buffer } )
    }

    /// Attempts to return a directory child by index.
    pub fn get(&self, index: u32) -> Option<&DirectoryChild> {
        self.children.get(index as usize)
    }

    pub fn length(&self) -> u32 {
        self.length
    }

    /// Returns the index of the selected child, or zero if no child is selected.
    pub fn selected(&self) -> u32 {
        self.selected.unwrap_or(0)
    }

    /// Attempts to select a child by index.
    pub fn set_selected(&mut self, index: u32) {
        if let Some(child) = self.get(index) {
            let buffer = child.path.as_buffer();
            self.name_buffer.populate(buffer);
            self.selected = Some(index);
        } else {
            self.name_buffer.clear();
            self.selected = None;
        }
    }

    pub fn child_name(&mut self) -> &mut CircularPathBuffer {
        &mut self.name_buffer
    }

    pub fn child_type(&self) -> Option<EntryType> {
        self.selected.and_then(|s| self.get(s).and_then(|i| Some(i.entry_type)))
    }

    pub fn child_path(&self) -> Option<BedrockFilePath> {
        self.selected.and_then(|s| self.get(s).and_then(|i| Some(i.path.clone())))
    }
}