use git2::{Cred, FetchOptions, RemoteCallbacks, Repository, build::CheckoutBuilder};
use std::env;
use std::fs;
use std::io;
use std::io::Write;
use std::path::Path;
use std::process::Command;

pub fn dir_size(path: &Path) -> std::io::Result<u64> {
    let mut size = 0;
    if path.is_dir() {
        for entry in fs::read_dir(path)? {
            let entry = entry?;
            let metadata = entry.metadata()?;
            if metadata.is_file() {
                size += metadata.len();
            } else if metadata.is_dir() {
                size += dir_size(&entry.path())?;
            }
        }
    }
    Ok(size)
}

pub fn get_editor() -> String {
    env::var("VISUAL")
        .or_else(|_| env::var("EDITOR"))
        .unwrap_or_else(|_| "nano".to_string())
}

pub fn open_in_editor(editor: &str, file: &str) -> Result<(), String> {
    let status = Command::new(editor)
        .arg(file)
        .status()
        .map_err(|e| format!("failed to execute editor: {}", e))?;

    if !status.success() {
        return Err(format!("editor exited with non-zero status: {}", status));
    }

    Ok(())
}

pub fn pull_repo(path: &Path) -> Result<(), git2::Error> {
    let repo = Repository::open(path)?;

    let head = repo.head()?;
    let branch = head
        .shorthand()
        .ok_or_else(|| git2::Error::from_str("Could not determine current branch"))?;

    let mut callbacks = RemoteCallbacks::new();
    callbacks.credentials(|_url, username_from_url, _allowed| {
        Cred::ssh_key_from_agent(username_from_url.unwrap())
    });

    let mut fetch_options = FetchOptions::new();
    fetch_options.remote_callbacks(callbacks);

    let mut remote = repo.find_remote("origin")?;
    remote.fetch(&[branch], Some(&mut fetch_options), None)?;

    let fetch_head = repo.find_reference("FETCH_HEAD")?;
    let fetch_commit = repo.reference_to_annotated_commit(&fetch_head)?;

    let (analysis, _pref) = repo.merge_analysis(&[&fetch_commit])?;

    if analysis.is_fast_forward() {
        println!("Fast-forwarding...");

        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)?;
        repo.checkout_head(Some(CheckoutBuilder::default().force()))?;
    } else if analysis.is_up_to_date() {
        println!("Already up to date.");
    } else {
        println!("Non fast-forward merge required (manual merge needed).");
    }

    Ok(())
}

pub fn yn_prompt(prompt: &str) -> bool {
    print!("{} [y/n]: ", prompt);
    io::stdout().flush().unwrap();

    // Read input from user
    let mut input = String::new();
    io::stdin().read_line(&mut input).unwrap();

    // Normalize input
    let input = input.trim().to_lowercase();

    match input.as_str() {
        "y" | "yes" | "" => true,
        _ => false,
    }
}