use anyhow::{Result, bail};
use std::{
    fs::File,
    io::{self, BufRead, prelude::*},
    path::{Path, PathBuf},
};

use crate::GIT_DIR;

pub mod gitignore;
pub mod head;
pub mod index;
pub mod object;

fn read_lines<P>(filename: P) -> Result<io::Lines<io::BufReader<File>>>
where
    P: AsRef<Path>,
{
    let file = File::open(filename)?;
    Ok(io::BufReader::new(file).lines())
}

pub fn normalize_path_in_worktree(path: &Path) -> Result<PathBuf> {
    let wt_root = get_worktree_root()?;
    let canon = path.canonicalize()?;
    let mut canon_it = canon.components();

    for wt_c in wt_root.components() {
        if let Some(c) = canon_it.next()
            && wt_c == c
        {
            continue;
        } else {
            bail!(
                "'{}' is outside repository at '{}'",
                path.display(),
                wt_root.display()
            );
        }
    }

    Ok(canon_it.as_path().to_path_buf())
}

pub fn get_worktree_root() -> Result<PathBuf> {
    let canon = Path::new(".").canonicalize()?;
    for ancestor in canon.ancestors() {
        let potential = ancestor.join(GIT_DIR);
        if potential.is_dir() {
            return Ok(ancestor.to_path_buf());
        }
    }
    bail!("not a git repository (or any parent up to mount point)")
}

pub fn get_git_root() -> Result<PathBuf> {
    Ok(get_worktree_root()?.join(GIT_DIR))
}

pub struct Ref {
    ref_name: String,
    commit_hash: String,
}

impl Ref {
    pub fn load(name: String) -> Result<Self> {
        let path = get_git_root()?.join(&name);

        let mut lines = read_lines(path)?;

        let content = match lines.next() {
            Some(line) => line?,
            _ => bail!(""),
        };

        Ok(Ref {
            ref_name: name,
            commit_hash: content,
        })
    }

    pub fn save(&self) -> Result<()> {
        let path = get_git_root()?.join("refs").join(&self.ref_name);

        let mut file = File::create(&path)?;

        file.write_all(self.commit_hash.as_bytes())?;

        Ok(())
    }
}