use crate::command_runner::CommandRunner;
use crate::symbols::Symbol;
use std::borrow::Borrow;
use std::error::Error;
use std::ffi::OsStr;
use std::marker::PhantomData;
use std::path::Path;

#[derive(Debug)]
pub struct Checkout<_C, C, P, S, B> {
  target: P,
  source: S,
  branch: B,
  command_runner: C,
  phantom: PhantomData<_C>,
}

impl<C, _C, P, S, B> Checkout<_C, C, P, S, B> {
  pub fn new(target: P, source: S, branch: B, command_runner: C) -> Self {
    Self {
      target,
      source,
      branch,
      command_runner,
      phantom: PhantomData::default(),
    }
  }
}

impl<C: CommandRunner, _C: Borrow<C>, P: AsRef<Path>, S, B> Checkout<C, _C, P, S, B> {
  fn _run_in_target_repo(&self, args: &[impl AsRef<OsStr>]) -> Result<Vec<u8>, Box<dyn Error>> {
    let mut new_args = vec![OsStr::new("-C"), self.target.as_ref().as_ref()];
    new_args.extend(args.iter().map(AsRef::as_ref));
    self.command_runner.borrow().get_output("git", &new_args)
  }
}

impl<C: CommandRunner, _C: Borrow<C>, P: AsRef<Path>, S: AsRef<str>, B: AsRef<str>> Symbol
  for Checkout<C, _C, P, S, B>
{
  fn target_reached(&self) -> Result<bool, Box<dyn Error>> {
    if !self.target.as_ref().exists() {
      return Ok(false);
    }
    self._run_in_target_repo(&["fetch", self.source.as_ref(), self.branch.as_ref()])?;
    // git rev-list resolves tag objects
    let fetch_head = self._run_in_target_repo(&["rev-list", "-1", "FETCH_HEAD"])?;
    let head = self._run_in_target_repo(&["rev-list", "-1", "HEAD"])?;
    Ok(fetch_head == head)
  }

  fn execute(&self) -> Result<(), Box<dyn Error>> {
    if !self.target.as_ref().exists() {
      return self.command_runner.borrow().run_successfully(
        "git",
        args![
          "clone",
          "--depth",
          "1",
          "-b",
          self.branch.as_ref(),
          self.source.as_ref(),
          self.target.as_ref(),
        ],
      );
    }
    self._run_in_target_repo(&["fetch", self.source.as_ref(), self.branch.as_ref()])?;
    self._run_in_target_repo(&["merge", "FETCH_HEAD"])?;
    Ok(())
  }
}

#[cfg(test)]
mod test {}