use anyhow::Context;
use object_store::{ObjectStore, aws::AmazonS3Builder, local::LocalFileSystem};
use std::sync::Arc;

pub struct StorageConfig(Arc<dyn ObjectStore>);

impl StorageConfig {
    pub fn from_env() -> anyhow::Result<Self> {
        let backend = std::env::var("POSTER_STORAGE_BACKEND")
            .context("POSTER_STORAGE_BACKEND required (valid values: s3, local)")?;

        let store: Arc<dyn ObjectStore> = match backend.as_str() {
            "s3" => build_s3_store(
                &std::env::var("MINIO_ENDPOINT").context("MINIO_ENDPOINT required")?,
                &std::env::var("MINIO_ACCESS_KEY_ID").context("MINIO_ACCESS_KEY_ID required")?,
                &std::env::var("MINIO_SECRET_ACCESS_KEY")
                    .context("MINIO_SECRET_ACCESS_KEY required")?,
                &std::env::var("MINIO_BUCKET").context("MINIO_BUCKET required")?,
                &std::env::var("MINIO_REGION").unwrap_or_else(|_| "minio".to_string()),
            )?,
            "local" => build_local_store(
                &std::env::var("POSTER_STORAGE_PATH")
                    .context("POSTER_STORAGE_PATH required when POSTER_STORAGE_BACKEND=local")?,
            )?,
            other => anyhow::bail!(
                "Unknown POSTER_STORAGE_BACKEND: {other:?}. Valid values: s3, local"
            ),
        };

        Ok(Self(store))
    }

    pub fn build_store(self) -> Arc<dyn ObjectStore> {
        self.0
    }
}

fn build_s3_store(
    endpoint: &str,
    access_key_id: &str,
    secret_access_key: &str,
    bucket: &str,
    region: &str,
) -> anyhow::Result<Arc<dyn ObjectStore>> {
    let store = AmazonS3Builder::new()
        .with_endpoint(endpoint)
        .with_access_key_id(access_key_id)
        .with_secret_access_key(secret_access_key)
        .with_bucket_name(bucket)
        .with_region(region)
        .with_allow_http(true)
        .build()
        .context("Failed to build S3/Minio store")?;
    Ok(Arc::new(store))
}

fn build_local_store(path: &str) -> anyhow::Result<Arc<dyn ObjectStore>> {
    std::fs::create_dir_all(path)
        .context("Failed to create poster storage directory")?;
    let store = LocalFileSystem::new_with_prefix(path)
        .context("Failed to initialise local file system store")?;
    Ok(Arc::new(store))
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn local_store_creates_dir_and_succeeds() {
        let dir = std::env::temp_dir()
            .join(format!("poster_test_{}", uuid::Uuid::new_v4()));
        let result = build_local_store(dir.to_str().unwrap());
        assert!(result.is_ok(), "expected Ok, got: {:?}", result.err());
        assert!(dir.exists(), "directory should have been created");
    }

    #[test]
    fn local_store_succeeds_if_dir_already_exists() {
        let dir = std::env::temp_dir()
            .join(format!("poster_test_{}", uuid::Uuid::new_v4()));
        std::fs::create_dir_all(&dir).unwrap();
        let result = build_local_store(dir.to_str().unwrap());
        assert!(result.is_ok());
    }
}