use git2::{BranchType, Repository};
use ignore::DirEntry;
use std::{cmp::Ordering, path::PathBuf, time::Duration};

use crate::project::Error;
use crate::project::Timestamp;
use crate::Project;

#[derive(Debug, Clone)]
pub struct GitProject {
    path_buf: PathBuf,
    latest_commit: Option<Duration>,
}

impl GitProject {
    fn new(path_buf: PathBuf) -> Result<Self, Error> {
        let latest_commit = Self::latest_commit(&path_buf).ok();
        Ok(Self {
            path_buf,
            latest_commit,
        })
    }

    fn latest_commit(path_buf: &PathBuf) -> Result<Duration, Error> {
        let repository = Repository::open(path_buf)?;
        let mut branches = repository.branches(Some(BranchType::Local))?;
        branches
            .try_fold(0, |latest, branch| {
                let (branch, _) = branch?;

                let name = branch
                    .name()?
                    .ok_or_else(|| git2::Error::from_str("Failed to find branch"))?;

                repository
                    .revparse_single(name)?
                    .peel_to_commit()
                    .map(|c| (c.time().seconds() as u64).max(latest))
            })
            .map(Duration::from_secs)
            .map_err(Into::into)
    }
}

impl Timestamp for GitProject {
    type Error = Error;

    fn timestamp(&self) -> Result<Duration, Self::Error> {
        match self.latest_commit {
            Some(t) => Ok(t),
            None => Self::latest_commit(&self.path_buf),
        }
    }
}

impl Project for GitProject {
    fn to_path_buf(&self) -> &PathBuf {
        &self.path_buf
    }
}

impl PartialEq for GitProject {
    fn eq(&self, other: &Self) -> bool {
        match (self.latest_commit, other.latest_commit) {
            (Some(time), Some(other_time)) => time.eq(&other_time),
            _ => false,
        }
    }
}

impl PartialOrd for GitProject {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        match (self.latest_commit, other.latest_commit) {
            (Some(time), Some(other_time)) => time.partial_cmp(&other_time),
            _ => None,
        }
    }
}

impl TryFrom<PathBuf> for GitProject {
    type Error = Error;

    fn try_from(value: PathBuf) -> Result<Self, Self::Error> {
        Self::new(value)
    }
}

impl TryFrom<DirEntry> for GitProject {
    type Error = Error;

    fn try_from(value: DirEntry) -> Result<Self, Self::Error> {
        Self::new(value.into_path())
    }
}

impl From<GitProject> for PathBuf {
    fn from(value: GitProject) -> Self {
        value.path_buf
    }
}