use git2::{Cred, PushOptions, Remote, RemoteCallbacks, Repository};
use sha2::{Sha256, Digest};

use crate::common::{self, Refractr};
use crate::config::ConfigFile;
use std::fs;
use std::env;
use std::path::{Path, PathBuf};
use git2::{Error, ErrorCode};
use hex;

fn set_up_work_dir(work_dir: PathBuf) -> String {
  if let Err(e) = fs::create_dir_all(&work_dir) {
    panic!("refractr: could not create working directory: {}: {}", work_dir.to_string_lossy(), e)
  }
  work_dir.to_string_lossy().to_string()
}

fn get_branches(repo: &Repository, branches: &Option<Vec<String>>) -> Vec<String> {
  match branches {
    Some(repo_branches) => repo_branches.to_vec(),
    None => {
      let mut strings = Vec::new();
      let remote_branches = match repo.branches(Some(git2::BranchType::Remote)) {
        Ok(b) => b,
        Err(e) => panic!("refractr: failed to get branches: {}", e)
      };
      for branch in remote_branches {
        if let Ok((b, _)) = branch {
          if let Ok(Some(name)) = b.name() {
            strings.push(name.to_string());
          }
        }
      }
      strings
    }
  }
}

fn fast_forward(repo_dir: &str, branches: &Option<Vec<String>>) -> Result<(), Error> {
  let repo = Repository::open(repo_dir)?;
  let branch_list: Vec<String> = get_branches(&repo, branches);

  repo.find_remote("origin")?.fetch(&branch_list, None, None)?;
  Ok(())
}

pub fn start(refractr: Refractr, cfgs: Vec<ConfigFile>) -> std::io::Result<()> {
  common::verbose(refractr.verbose, 3, format!("Starting main refractr loop"));
  for cfg in &cfgs {
    // set up the working directory
    common::verbose(refractr.verbose, 3, format!("Loaded config: {}", cfg.path));
    let path_str = set_up_work_dir(match &cfg.config.work_dir {
      None => {
        if cfg!(windows) {
          PathBuf::from(format!("\"{}\\refractr\"", match env::var("TEMP") {
            Ok(val) => val,
            Err(_) => format!("This shouldn't happen!")
          }))
        } else {
          PathBuf::from("/tmp/refractr")
        }
      },
      Some(path) => PathBuf::from(path)
    });

    common::verbose(refractr.verbose, 2, format!("Created working directory: {}", &path_str));
    let repo_name = match &cfg.config.from.split("/").last() {
      Some(split) => split.to_string(),
      None => panic!("refractr: failed to parse repository name")
    };

    // make initial clone
    common::verbose(refractr.verbose, 1, format!("Cloning repository: {}", &cfg.config.from));
    let repo_dir = &format!("{}/{}", &path_str, repo_name);
    let repo = match Repository::clone(&cfg.config.from, Path::new(&repo_dir)) {
      Ok(repo) => repo,
      Err(_) => {
        eprintln!("refractr: warning: found existing repo at {}, attempting to use", repo_dir);
        match fast_forward(repo_dir, &cfg.config.branches) {
          Ok(_) => if let Ok(repo) = Repository::open(Path::new(&repo_dir)) {
            repo
          } else {
            panic!("refractr: failed to obtain existing repo")
          },
          Err(e) => panic!("refractr: failed to obtain existing repo: {}", e)
        }
      }
    };

    // create remotes for each "to" repo
    let mut remote_list: Vec<Remote<'_>> = Vec::new();
    for to in &cfg.config.to {
      let mut hasher = Sha256::new();
      hasher.update(to);
      let remote_id = format!("refractr-{}", &hex::encode(hasher.finalize())[..8]);
      common::verbose(refractr.verbose, 2, format!("Attempting to create remote {} for url {}", remote_id, to));
      match repo.remote(remote_id.as_str(), to) {
        Ok(r) => remote_list.push(r),
        Err(e) => {
          if e.code() == ErrorCode::Exists {
            eprintln!("refractr: warning: remote {} already exists, skipping", remote_id)
          } else {
            panic!("refractr: failed to create remote: {}", e);
          }
        }
      }
    }

    for mut remote in remote_list {
      let mut callbacks = RemoteCallbacks::new();
      callbacks.credentials(|_,_,_| Cred::ssh_key("git", None, &Path::new(&cfg.config.git.ssh_identity_file), None));
      let mut push_options = PushOptions::new();
      push_options.remote_callbacks(callbacks);

      match remote.push::<&str>(&["refs/heads/master"], Some(&mut push_options)) {
        Ok(_) => (),
        Err(e) => {
          eprintln!("refractr: failed to push to remote: {}: {}", remote.url().unwrap(), e)
        }
      }
    }
  }

  Ok(())
}