//! Hive-wide knowledge repository management.
//!
//! `internal/hive-knowledge` on the forge is cloned to
//! [`LOCAL_DIR`] and bind-mounted read-only into every agent container
//! at `/hive-knowledge`. Agents read documents from it directly and
//! contribute by forking the repo and opening PRs — they never write
//! to the bind-mounted path inside the container.
//!
//! hive-c0re maintains the local clone. A Forgejo webhook notifies it
//! on push to main so agents always see an up-to-date snapshot.

use anyhow::{Context, Result};

pub const ORG: &str = "internal";
pub const REPO: &str = "knowledge";

/// Host-side path for the local clone. Also referenced from
/// `lifecycle.rs` (bind-mount source) and the dashboard webhook handler.
pub const LOCAL_DIR: &str = "/var/lib/hyperhive/knowledge";

/// In-container mount point for the knowledge repo. Bind-mounted
/// read-only from [`LOCAL_DIR`] into every agent container.
pub const CONTAINER_MOUNT: &str = "/knowledge";

/// Default README pushed to a freshly created `internal/knowledge` repo.
/// Short explanation + empty ToC with an HTML comment instructing contributors
/// to add entries when they create new files.
const README_CONTENT: &str = "\
# knowledge

Hive-wide reference documents: conventions, runbooks, and anything that \
every agent should know.

## How to contribute

1. Fork this repo into your own namespace on the forge.
2. Create a branch, add or update a document.
3. Open a pull request — the operator reviews and merges.
4. Every agent container updates automatically on merge.

Do **not** push directly to `main` — agents have read-only access.

## Contents

<!-- Add an entry here each time you create a new document:
- [Title](path/to/file.md) - one-line description
-->
";

/// Clone `internal/knowledge` to [`LOCAL_DIR`] if it is not already a git
/// repository. `core_token` authenticates the HTTPS clone so private repos
/// work. Idempotent — skips if `LOCAL_DIR/.git` exists.
///
/// When the upstream repo is empty (freshly created), seeds it with a
/// README.md before returning so the local clone is always non-empty and
/// agents see a useful starting document.
///
/// Called once at hive-c0re startup after `forge::ensure_all`.
pub async fn ensure_local_clone(core_token: &str) -> Result<()> {
    let git_dir = std::path::Path::new(LOCAL_DIR).join(".git");
    if git_dir.exists() {
        tracing::debug!("knowledge: local clone already present at {LOCAL_DIR}");
        return Ok(());
    }
    std::fs::create_dir_all(LOCAL_DIR).context("create knowledge local dir")?;
    // Embed credentials in the URL — safe for localhost-only forge.
    let url = format!("http://core:{core_token}@localhost:3000/{ORG}/{REPO}.git");
    let out = tokio::process::Command::new("git")
        .args(["clone", &url, LOCAL_DIR])
        .output()
        .await
        .context("git clone knowledge repo")?;
    if !out.status.success() {
        let stderr = String::from_utf8_lossy(&out.stderr).trim().to_owned();
        anyhow::bail!("git clone {ORG}/{REPO} failed: {stderr}");
    }
    tracing::info!("knowledge: cloned {ORG}/{REPO} to {LOCAL_DIR}");
    // If the repo is brand new (no commits), seed it with a README.
    let head_out = tokio::process::Command::new("git")
        .args(["-C", LOCAL_DIR, "rev-parse", "HEAD"])
        .output()
        .await
        .context("git rev-parse HEAD")?;
    if !head_out.status.success() {
        seed_readme(core_token).await?;
    }
    Ok(())
}

/// Write the initial README.md, commit, and push to `internal/knowledge`.
/// Called only when the upstream repo is empty.
async fn seed_readme(core_token: &str) -> Result<()> {
    let readme = std::path::Path::new(LOCAL_DIR).join("README.md");
    std::fs::write(&readme, README_CONTENT).context("write README.md")?;
    // Set a minimal git identity for the seed commit.
    for (k, v) in [("user.email", "core@hive"), ("user.name", "hive-c0re")] {
        let out = tokio::process::Command::new("git")
            .args(["-C", LOCAL_DIR, "config", k, v])
            .output()
            .await
            .with_context(|| format!("git config {k}"))?;
        if !out.status.success() {
            let stderr = String::from_utf8_lossy(&out.stderr).trim().to_owned();
            anyhow::bail!("git config {k} failed: {stderr}");
        }
    }
    for args in [
        vec!["add", "README.md"],
        vec!["commit", "-m", "init: seed README"],
    ] {
        let out = tokio::process::Command::new("git")
            .args(["-C", LOCAL_DIR].iter().chain(args.iter()))
            .output()
            .await
            .with_context(|| format!("git {:?}", args))?;
        if !out.status.success() {
            let stderr = String::from_utf8_lossy(&out.stderr).trim().to_owned();
            anyhow::bail!("git {:?} failed: {stderr}", args);
        }
    }
    let url = format!("http://core:{core_token}@localhost:3000/{ORG}/{REPO}.git");
    let out = tokio::process::Command::new("git")
        .args(["-C", LOCAL_DIR, "push", &url, "HEAD:main"])
        .output()
        .await
        .context("git push knowledge README")?;
    if out.status.success() {
        tracing::info!("knowledge: seeded README.md and pushed to {ORG}/{REPO}");
        Ok(())
    } else {
        let stderr = String::from_utf8_lossy(&out.stderr).trim().to_owned();
        anyhow::bail!("git push {ORG}/{REPO} failed: {stderr}")
    }
}

/// Pull the latest changes in the local clone. Called from the webhook
/// handler on every push to `internal/hive-knowledge` main. Uses
/// `--ff-only` so a force-push to the knowledge repo never wedges the
/// local copy silently; an error triggers a re-clone fallback.
pub async fn pull() -> Result<()> {
    // Sanity: if the clone is missing (e.g. storage was wiped), refuse
    // to pull and let the caller decide whether to re-clone.
    let git_dir = std::path::Path::new(LOCAL_DIR).join(".git");
    if !git_dir.exists() {
        anyhow::bail!("knowledge: {LOCAL_DIR}/.git not found — clone first");
    }
    let out = tokio::process::Command::new("git")
        .args(["-C", LOCAL_DIR, "pull", "--ff-only"])
        .output()
        .await
        .context("git pull hive-knowledge")?;
    if out.status.success() {
        let stdout = String::from_utf8_lossy(&out.stdout).trim().to_owned();
        tracing::info!(result = %stdout, "knowledge: pull succeeded");
        Ok(())
    } else {
        let stderr = String::from_utf8_lossy(&out.stderr).trim().to_owned();
        anyhow::bail!("git pull {ORG}/{REPO} failed: {stderr}")
    }
}