//! Binary blob storage in the message-log `SQLite` database (e.g. images,
//! attachments), keyed by session id and an arbitrary blob key.

use rusqlite::{Connection, params};
use anyhow::Result;

/// 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)`.
///
/// 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();
    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],
    )?;
    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>>> {
    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(0),
    );
    match result {
        Ok(data) => Ok(Some(data)),
        Err(rusqlite::Error::QueryReturnedNoRows) => Ok(None),
        Err(e) => Err(e.into()),
    }
}

/// Delete a blob for a session by key.
///
/// Return: `Ok(true)` if a row was deleted, `Ok(false)` if no matching
/// row existed.
#[allow(dead_code)]
pub fn delete_blob(conn: &Connection, session_id: &str, blob_key: &str) -> Result<bool> {
    let rows = conn.execute(
        "DELETE FROM blobs WHERE session_id = ?1 AND blob_key = ?2",
        params![session_id, blob_key],
    )?;
    Ok(rows > 0)
}

/// 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>> {
    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?);
    }
    Ok(keys)
}