use crate::error::Error::{GenericError, NoDefaultRemoteFound};
use crate::error::Result;
use git2::{Branch, BranchType, Remote, Repository};

const DEFAULT_REMOTE_NAME: &str = "origin";

pub(crate) fn get_current_branch(repo: &Repository) -> Result<Option<Branch<'_>>> {
    for b in repo.branches(None)? {
        let branch = b?.0;
        if branch.is_head() {
            return Ok(Some(branch));
        }
    }
    Ok(None)
}

pub(crate) fn get_current_branch_name(repo: &Repository) -> Result<String> {
    Ok(get_current_branch(&repo)?
        .ok_or(GenericError("Failed to get current branch".to_string()))?
        .name()?
        .ok_or(GenericError("Failed to get current branch name".to_string()))?
        .to_string())
}

pub(crate) fn local_branch_names(repo: &Repository) -> Result<Vec<String>> {
    let mut branches = Vec::new();
    for branch in repo.branches(Some(BranchType::Local))? {
        let (branch, _) = branch?;
        let name = branch.name_bytes()?;
        let name = bytes_to_string(name)?;
        branches.push(name);
    }
    Ok(branches)
}

pub(crate) fn remote_branch_names(repo: &Repository) -> Result<Vec<String>> {
    let mut branches = Vec::new();
    for branch in repo.branches(Some(BranchType::Remote))? {
        let (branch, _) = branch?;
        let name = branch.name_bytes()?;
        let name = bytes_to_string(name)?;
        if name.ends_with("/HEAD") {
            continue;
        }
        branches.push(name);
    }
    Ok(branches)
}

pub(crate) fn bytes_to_string(bytes: &[u8]) -> Result<String> {
    Ok(String::from_utf8(bytes.to_vec())?)
}

pub(crate) fn get_default_remote_for_push_in_repo(repo: &'_ Repository) -> Result<Remote<'_>> {
    let name = get_default_remote_name_for_push_in_repo(repo)?;
    let remote = repo.find_remote(&name)?;
    Ok(remote)
}

pub(crate) fn get_default_remote_name_for_push_in_repo(repo: &Repository) -> Result<String> {
    let config = repo.config()?;

    let branch = get_current_branch(repo)?;

    if let Some(branch) = branch {
        let remote_name = bytes_to_string(branch.name_bytes()?)?;

        let entry_name = format!("branch.{}.pushRemote", &remote_name);

        if let Ok(entry) = config.get_entry(&entry_name) {
            return bytes_to_string(entry.value_bytes());
        }

        if let Ok(entry) = config.get_entry("remote.pushDefault") {
            return bytes_to_string(entry.value_bytes());
        }

        let entry_name = format!("branch.{}.remote", &remote_name);

        if let Ok(entry) = config.get_entry(&entry_name) {
            return bytes_to_string(entry.value_bytes());
        }
    }

    get_default_remote_name_in_repo(repo)
}

pub(crate) fn get_default_remote_in_repo(repo: &'_ Repository) -> Result<Remote<'_>> {
    let name = get_default_remote_name_in_repo(repo)?;
    let remote = repo.find_remote(&name)?;
    Ok(remote)
}

pub(crate) fn get_default_remote_name_in_repo(repo: &Repository) -> Result<String> {
    let remotes = repo.remotes()?;

    if remotes.is_empty() {
        return Err(NoDefaultRemoteFound);
    }

    // if `origin` exists return that
    let found_origin = remotes.iter().any(|r| r.is_some_and(|r| r == DEFAULT_REMOTE_NAME));
    if found_origin {
        return Ok(DEFAULT_REMOTE_NAME.into());
    }

    // if only one remote exists, pick that
    if remotes.len() == 1 {
        let first_remote = remotes
            .iter()
            .next()
            .flatten()
            .map(String::from)
            .ok_or_else(|| GenericError("no remote found".into()))?;

        return Ok(first_remote);
    }

    // inconclusive
    Err(NoDefaultRemoteFound)
}