//! `internal/meta` on the forge: the repo the swarm meta flake is committed to
//! (`crate::meta_flake`), and the read grant each hive's account holds on it.

use anyhow::{Context, Result};
use base64::Engine as _;
use forgejo_api::structs::{
    AddCollaboratorOptionPermission, ChangeFileOperation, ChangeFileOperationOperation,
    ChangeFilesOptions,
};

use super::objects::SHARED_ORG;
use super::{Client, DefaultBranchFiles, is_repo_not_found};
use crate::meta_flake::{META_REPO, MetaFile, MetaForge};

impl MetaForge for Client {
    async fn head_files(
        &self,
        owner: &str,
        repo: &str,
        branch: Option<&str>,
        paths: &[&str],
    ) -> Result<Option<DefaultBranchFiles>> {
        self.branch_files(owner, repo, branch, paths).await
    }

    async fn ensure_meta_repo(&self) -> Result<()> {
        self.create_shared_repo(SHARED_ORG, META_REPO, true).await
    }

    async fn grant_meta_read(&self, login: &str) -> Result<()> {
        self.add_collaborator_to(
            SHARED_ORG,
            META_REPO,
            login,
            AddCollaboratorOptionPermission::Read,
        )
        .await
    }

    async fn commits_ahead(
        &self,
        owner: &str,
        repo: &str,
        base: &str,
        head: &str,
    ) -> Result<Option<u64>> {
        let basehead = format!("{base}...{head}");
        match self
            .api
            .call(|api| api.repo_compare_diff(owner, repo, &basehead).into_future())
            .await
        {
            Ok(compare) => Ok(Some(
                u64::try_from(compare.total_commits.unwrap_or(0)).unwrap_or(0),
            )),
            Err(e) if is_repo_not_found(&e) => Ok(None),
            Err(e) => Err(e).with_context(|| format!("compare {basehead} in {owner}/{repo}")),
        }
    }

    async fn commit_meta(&self, message: &str, files: Vec<MetaFile>) -> Result<()> {
        let ops: Vec<ChangeFileOperation> = files
            .into_iter()
            .map(|f| ChangeFileOperation {
                content: Some(base64::engine::general_purpose::STANDARD.encode(f.bytes)),
                from_path: None,
                operation: if f.sha.is_some() {
                    ChangeFileOperationOperation::Update
                } else {
                    ChangeFileOperationOperation::Create
                },
                path: f.path.to_owned(),
                sha: f.sha,
            })
            .collect();
        self.api
            .call(|api| {
                api.repo_change_files(
                    SHARED_ORG,
                    META_REPO,
                    ChangeFilesOptions {
                        author: None,
                        branch: None,
                        committer: None,
                        dates: None,
                        files: ops.clone(),
                        force_overwrite_new_branch: None,
                        message: Some(message.to_owned()),
                        new_branch: None,
                        signoff: None,
                    },
                )
                .into_future()
            })
            .await
            .with_context(|| format!("commit to {SHARED_ORG}/{META_REPO}"))?;
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use std::sync::{Arc, Mutex};

    use super::*;

    /// A stand-in forge answering Forgejo's compare endpoint: `total_commits`
    /// of 3 for `aaa...bbb`, 0 for `bbb...aaa`, 404 for anything else.
    /// Records every request's path.
    async fn compare_forge() -> (Client, Arc<Mutex<Vec<String>>>) {
        use axum::http::{StatusCode, Uri};

        let seen = Arc::new(Mutex::new(Vec::new()));
        let recorded = Arc::clone(&seen);
        let app = axum::Router::new().fallback(move |uri: Uri| {
            let recorded = Arc::clone(&recorded);
            async move {
                recorded.lock().unwrap().push(uri.path().to_owned());
                match uri.path() {
                    "/api/v1/repos/o/r/compare/aaa...bbb" => (
                        StatusCode::OK,
                        r#"{"total_commits":3,"commits":[],"files":[]}"#,
                    ),
                    "/api/v1/repos/o/r/compare/bbb...aaa" => {
                        (StatusCode::OK, r#"{"total_commits":0,"commits":[]}"#)
                    }
                    _ => (StatusCode::NOT_FOUND, r#"{"message":"not found"}"#),
                }
            }
        });
        let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
        let url = url::Url::parse(&format!("http://{}/", listener.local_addr().unwrap())).unwrap();
        tokio::spawn(async move { axum::serve(listener, app).await });
        let api = crate::forge::api::tests::fixed(url.clone(), "stub-token");
        (Client { api, url }, seen)
    }

    #[tokio::test]
    async fn commits_ahead_reads_the_compare_endpoint_as_base_dots_head() {
        let (client, seen) = compare_forge().await;
        assert_eq!(
            client.commits_ahead("o", "r", "aaa", "bbb").await.unwrap(),
            Some(3)
        );
        assert_eq!(
            client.commits_ahead("o", "r", "bbb", "aaa").await.unwrap(),
            Some(0)
        );
        assert_eq!(
            *seen.lock().unwrap(),
            [
                "/api/v1/repos/o/r/compare/aaa...bbb",
                "/api/v1/repos/o/r/compare/bbb...aaa"
            ]
        );
    }

    #[tokio::test]
    async fn a_commit_the_forge_lacks_is_no_count_not_an_error() {
        let (client, _) = compare_forge().await;
        assert_eq!(
            client.commits_ahead("o", "r", "aaa", "zzz").await.unwrap(),
            None
        );
    }
}