//! Binary blob storage in the message-log `SQLite` database (e.g. images,
//! attachments), keyed by session id and an arbitrary blob key.
use anyhow::Result;
use rusqlite::{params, Connection};

/// Insert or overwrite a blob for a session under `blob_key`.
///
/// Flow: compute current timestamp -> `INSERT OR REPLACE` into `blobs`
/// keyed on `(session_id, blob_key)`.
///
/// `INSERT OR REPLACE` is used so re-uploading the same key overwrites
/// the previous blob rather than failing on the UNIQUE constraint.
///
/// Return: `Ok(())` on success, or the underlying `SQLite` error.
pub fn store_blob(
    conn: &Connection,
    session_id: &str,
    blob_key: &str,
    data: &[u8],
    mime_type: Option<&str>,
) -> Result<()> {
    let created_at = chrono::Utc::now().timestamp_millis();
    tracing::debug!(%session_id, %blob_key, size = data.len(), "store_blob");
    conn.execute(
        "INSERT OR REPLACE INTO blobs (session_id, blob_key, data, mime_type, created_at) VALUES (?1, ?2, ?3, ?4, ?5)",
        params![session_id, blob_key, data, mime_type, created_at],
    )?;
    tracing::info!(%session_id, %blob_key, "store_blob — stored");
    Ok(())
}

/// Fetch a blob's bytes for a session by key.
///
/// Return: `Ok(Some(data))` if found, `Ok(None)` if no matching row
/// exists, `Err` for any other `SQLite` failure.
pub fn retrieve_blob(
    conn: &Connection,
    session_id: &str,
    blob_key: &str,
) -> Result<Option<Vec<u8>>> {
    tracing::debug!(%session_id, %blob_key, "retrieve_blob");
    let result = conn.query_row(
        "SELECT data FROM blobs WHERE session_id = ?1 AND blob_key = ?2",
        params![session_id, blob_key],
        |row| row.get::<_, Vec<u8>>(0),
    );
    match result {
        Ok(data) => {
            tracing::debug!(%session_id, %blob_key, size = data.len(), "retrieve_blob — found");
            Ok(Some(data))
        }
        Err(rusqlite::Error::QueryReturnedNoRows) => {
            tracing::debug!(%session_id, %blob_key, "retrieve_blob — not found");
            Ok(None)
        }
        Err(e) => {
            tracing::error!(%session_id, %blob_key, error = %e, "retrieve_blob — query failed");
            Err(e.into())
        }
    }
}

/// List all blob keys stored for a session, oldest first.
///
/// Return: `Ok(Vec<String>)` of keys ordered by `created_at`, or the
/// underlying `SQLite` error.
pub fn list_blob_keys(conn: &Connection, session_id: &str) -> Result<Vec<String>> {
    tracing::debug!(%session_id, "list_blob_keys");
    let mut stmt =
        conn.prepare("SELECT blob_key FROM blobs WHERE session_id = ?1 ORDER BY created_at ASC")?;
    let rows = stmt.query_map(params![session_id], |row| row.get::<_, String>(0))?;
    let mut keys = Vec::new();
    for row in rows {
        keys.push(row?);
    }
    tracing::debug!(%session_id, count = keys.len(), "list_blob_keys — done");
    Ok(keys)
}