use std::path::{Path, PathBuf};

use crate::error::{GitError, GitResult};
use crate::pb::RepositoryHeader;

pub struct GitBare {
    pub bare_dir: PathBuf,
}

impl GitBare {
    pub fn gix_repo(&self) -> GitResult<gix::Repository> {
        gix::open(&self.bare_dir)
            .map_err(|e| GitError::Internal(format!("failed to open gix repository: {e}")))
    }

    pub fn from_repository_header(header: &RepositoryHeader) -> GitResult<Self> {
        let storage_path = header.storage_path.trim();
        let relative_path = header.relative_path.trim();
        let storage_name = header.storage_name.trim();
        let _ = storage_name; // reserved for future sharding logic

        // Build base path: storage_path if given, else relative_path alone
        let base = if !storage_path.is_empty() {
            let p = Path::new(storage_path);
            if !p.is_absolute() {
                return Err(GitError::InvalidArgument(
                    "storage_path must be an absolute path".into(),
                ));
            }
            PathBuf::from(p)
        } else if !relative_path.is_empty() {
            // relative_path alone is rejected unless absolute
            return Err(GitError::InvalidArgument(
                "relative_path requires storage_path to be set".into(),
            ));
        } else {
            return Err(GitError::InvalidArgument("empty repository path".into()));
        };

        // Join relative_path if provided
        let bare_dir = if !relative_path.is_empty() && !storage_path.is_empty() {
            let candidate = base.join(relative_path);
            // Canonicalize to resolve any `..` / symlinks, then check still under base
            let canonical = candidate
                .canonicalize()
                .unwrap_or_else(|_| candidate.clone());
            // Path traversal check: canonical resolved dir must start with base
            let base_canon = base.canonicalize().unwrap_or_else(|_| base.clone());
            if !canonical.starts_with(&base_canon) {
                return Err(GitError::InvalidArgument(format!(
                    "path traversal detected: {relative_path} escapes storage root"
                )));
            }
            canonical
        } else if !storage_path.is_empty() {
            base.canonicalize().unwrap_or(base)
        } else {
            return Err(GitError::InvalidArgument("empty repository path".into()));
        };

        // Validate bare_dir exists, is a directory, and is readable
        if !bare_dir.exists() {
            return Err(GitError::RepoNotFound);
        }
        if !bare_dir.is_dir() {
            return Err(GitError::InvalidArgument(format!(
                "not a directory: {}",
                bare_dir.display()
            )));
        }

        // Accept either bare repos (HEAD file) or non-bare (HEAD + .git)
        let head_path = bare_dir.join("HEAD");
        if !head_path.exists() {
            // Maybe it's a non-bare repo
            let git_dir = bare_dir.join(".git");
            if git_dir.is_dir() && git_dir.join("HEAD").exists() {
                return Ok(Self { bare_dir: git_dir });
            }
            return Err(GitError::NotBareRepository);
        }

        Ok(Self { bare_dir })
    }

    /// Detect the repository's object format (SHA-1 or SHA-256).
    pub fn object_format(&self) -> crate::pb::ObjectFormat {
        let repo = self.gix_repo().ok();
        let kind = repo
            .map(|r| r.object_hash())
            .unwrap_or(gix::hash::Kind::Sha1);
        match kind {
            gix::hash::Kind::Sha1 => crate::pb::ObjectFormat::Sha1,
            gix::hash::Kind::Sha256 => crate::pb::ObjectFormat::Sha256,
            _ => crate::pb::ObjectFormat::Unspecified,
        }
    }

    /// Convert a hex object id to a protobuf Oid.
    ///
    /// `Oid.value` is the binary hash bytes, while `Oid.hex` keeps the printable
    /// lowercase representation for clients that prefer string IDs.
    pub fn oid_to_pb(&self, hex: impl Into<String>) -> crate::pb::Oid {
        let hex = hex.into().to_lowercase();
        let format = self.object_format();
        crate::pb::Oid {
            value: crate::oid::hex_to_bytes(&hex).unwrap_or_default(),
            hex,
            format: format as i32,
        }
    }
}