use git2::build::CheckoutBuilder;
use git2::{BranchType, Cred, PushOptions, RemoteCallbacks, Repository};
use sha2::{Sha256, Digest};

use crate::common::{self, Refractr};
use crate::config::{Config, ConfigFile};
use std::fs;
use std::env;
use std::thread;
use std::time;
use std::path::{Path, PathBuf};
use git2::{Error, ErrorCode};
use hex;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;

struct OpenedRepository {
  repo: Repository,
  path: String,
  remotes: Vec<String>,
  cfg: Config,
}

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>>, refs: bool) -> Vec<String> {
  match branches {
    Some(repo_branches) => {
      if refs {
        let mut refs_branches = Vec::new();
        for branch in repo_branches {
          refs_branches.push(format!("refs/heads/{}", branch));
        }
        refs_branches
      } else {
        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() {
            if refs {
              strings.push(format!("refs/heads/{}", name.to_string()))
            } else {
              strings.push(name.to_string());
            }
          }
        }
      }
      strings
    }
  }
}

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

  common::verbose(refractr.verbose, 2, format!("Pulling origin"));
  repo.find_remote("origin")?.fetch(&branch_list, None, None)?;

  let fetch_head = repo.find_reference("FETCH_HEAD")?;
  let fetch_commit = repo.reference_to_annotated_commit(&fetch_head)?;
  let analysis = repo.merge_analysis(&[&fetch_commit])?;
  if analysis.0.is_fast_forward() {
    for branch in branch_list {
      let refname = format!("refs/heads/{}", branch);
      let mut reference = repo.find_reference(&refname)?;
      reference.set_target(fetch_commit.id(), "Fast-forward")?;
      repo.set_head(&refname)?;
      let _ = repo.checkout_head(Some(CheckoutBuilder::default().force()));
    }
  }

  Ok(())

}

fn make_remotes<'a> (refractr: &Refractr, repo: &'a Repository, cfg: &ConfigFile) -> Vec<String> {
  // create remotes for each "to" repo
  let mut remote_list = 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(_) => remote_list.push(remote_id),
      Err(e) => {
        if e.code() == ErrorCode::Exists {
          eprintln!("refractr: warning: remote {} already exists, skipping", remote_id);
          remote_list.push(remote_id)
        } else {
          panic!("refractr: failed to create remote: {}", e);
        }
      }
    }
  }

  remote_list
}

fn push_remotes(refractr: &Refractr, cfg: &Config, repo: &Repository, remote_list: &Vec<String>) {
  for id in remote_list {
    let mut remote = repo.find_remote(&id).unwrap();
    common::verbose(refractr.verbose, 1, format!("Pushing to remote: {}", remote.url().unwrap()));
    let mut callbacks = RemoteCallbacks::new();
    callbacks.credentials(|_,_,_| Cred::ssh_key("git", None, &Path::new(&cfg.git.ssh_identity_file), None));
    let mut push_options = PushOptions::new();
    push_options.remote_callbacks(callbacks);

    let mut refs = Vec::new();
    let strings = get_branches(&repo, &cfg.branches, true);
    for branch in &strings {
      refs.push(branch.as_str());
    }

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

fn looper(refractr: Refractr, repos: Vec<OpenedRepository>) {
  let mut current_ints = Vec::new();
  let running = Arc::new(AtomicBool::new(true));
  let r = running.clone();
  let count = repos.len();
  for i in 0..repos.len() {
    current_ints.push(u64::from(repos[i].cfg.schedule.interval.unwrap().unsigned_abs()));
  };
  let original_ints = current_ints.clone();

  ctrlc::set_handler(move || {
    r.store(false, Ordering::SeqCst);
  }).expect("Failed to set ^C handler");

  common::verbose(refractr.verbose, 1, format!("Starting scheduled loop"));
  let min = *current_ints.iter().min().unwrap();
  let mut do_break = false;
  while !do_break {
    do_break = true;
    let sleep_int = time::Duration::from_secs(min);
    let now = time::Instant::now();

    common::verbose(refractr.verbose, 2, format!("Sleeping for {} seconds", sleep_int.as_secs()));
    while running.load(Ordering::SeqCst) {
      thread::sleep(time::Duration::from_secs(1));
      if now.elapsed().as_secs() >= sleep_int.as_secs() {
        common::verbose(refractr.verbose, 3, format!("Thread has awoken!"));
        for i in 0..count {
          current_ints[i] -= now.elapsed().as_secs();
          if i <= 0 {
            current_ints[i] = original_ints[i].clone();
            common::verbose(refractr.verbose, 2, format!("Interval for {} has arrived, pulling", repos[i].cfg.from));
            let _ = fast_forward(&refractr, &repos[i].path, &repos[i].cfg.branches);
            push_remotes(&refractr, &repos[i].cfg, &repos[i].repo, &repos[i].remotes);
          }
        }
        do_break = false;
        break
      }
    }
  }
  common::verbose(refractr.verbose, 1, format!("Exited looper due to ^C"));

}

pub fn run(refractr: Refractr, cfgs: Vec<ConfigFile>) -> std::io::Result<()> {
  common::verbose(refractr.verbose, 3, format!("Starting main refractr loop"));
  let mut loop_repos = Vec::new();

  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(&refractr, &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)
        }
      }
    };

    
    let repo_fresh = Repository::open(Path::new(&repo_dir)).unwrap();
    let remotes = make_remotes(&refractr, &repo_fresh, &cfg);
    push_remotes(&refractr, &cfg.config, &repo, &remotes);
    if cfg.config.schedule.enabled {
      loop_repos.push(OpenedRepository {
        repo,
        path: repo_dir,
        remotes,
        cfg: cfg.config
      });
    }
  }

  if loop_repos.len() >= 1 {
    common::verbose(refractr.verbose, 2, format!("{} configs have schedules enabled, setting up looper", loop_repos.len()));
    looper(refractr, loop_repos);
  } else {
    common::verbose(refractr.verbose, 2, format!("No scheduled configs found, exiting refractr"));
  }

  Ok(())
}