use crate::commands::Command;

use crate::error::{CommandError, CommandErrorKind};

use crate::ui::Ui;

use hg::operations::FindRoot;

pub const HELP_TEXT: &str = "

Print the current repo requirements.

";

pub struct DebugRequirementsCommand {}

impl DebugRequirementsCommand {

    pub fn new() -> Self {

        DebugRequirementsCommand {}

    }

}

impl Command for DebugRequirementsCommand {

    fn run(&self, ui: &Ui) -> Result<(), CommandError> {

        let root = FindRoot::new().run()?;

        let requires = root.join(".hg").join("requires");

        let requirements = match std::fs::read(requires) {

            Ok(bytes) => bytes,

            // Treat a missing file the same as an empty file.

            // From `mercurial/localrepo.py`:

            // > requires file contains a newline-delimited list of

            // > features/capabilities the opener (us) must have in order to use

            // > the repository. This file was introduced in Mercurial 0.9.2,

            // > which means very old repositories may not have one. We assume

            // > a missing file translates to no requirements.

            Err(error) if error.kind() == std::io::ErrorKind::NotFound => Vec::new(),

            Err(error) => Err(CommandErrorKind::FileError(error))?,

        };

        ui.write_stdout(&requirements)?;

        Ok(())

    }

}