//! Filesystem lifecycle for media artifacts.
//!
//! The DB-aware gateway hides deleted/hidden uploads, but the bytes still sit on
//! a fixed-size disk until something removes them. This module is that
//! something: best-effort unlinking on delete, plus a periodic reaper that
//! sweeps files belonging to soft-deleted rows (catching anything an in-process
//! unlink missed — e.g. a crash between the DB commit and the unlink).

use std::path::Path;

use sqlx::PgPool;

use crate::models::upload::DeletedPaths;

/// Best-effort removal of an upload's three on-disk artifacts. A missing file is
/// not an error (it may already be gone, or never existed for videos without a
/// preview); anything else is logged but never propagated — losing the bytes
/// must not fail the user's delete.
pub async fn unlink_media(media_path: &Path, paths: &DeletedPaths) {
    let candidates = [
        Some(&paths.original),
        paths.preview.as_ref(),
        paths.thumbnail.as_ref(),
    ];
    for rel in candidates.into_iter().flatten() {
        let abs = media_path.join(rel);
        match tokio::fs::remove_file(&abs).await {
            Ok(()) => {}
            Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
            Err(e) => tracing::warn!(path = %rel, error = ?e, "media unlink failed"),
        }
    }
}

/// Reaper: remove on-disk files for uploads that were soft-deleted more than
/// `grace` ago, then hard-delete those rows so they don't accumulate. Strictly
/// DB-row-driven — it never walks the filesystem, so it can never remove a file
/// belonging to a live upload.
pub async fn reap_deleted(pool: &PgPool, media_path: &Path) {
    // Snapshot the exact rows (id + paths) we are about to unlink, and delete by
    // those ids — NOT by re-evaluating the `deleted_at < now - 1 day` predicate.
    // A row that crosses the 1-day line *during* the unlink loop would otherwise
    // be hard-deleted by the second predicate without ever having its files
    // unlinked → a permanent orphan.
    let rows: Vec<(uuid::Uuid, String, Option<String>, Option<String>)> = match sqlx::query_as(
        "SELECT id, original_path, preview_path, thumbnail_path
         FROM upload
         WHERE deleted_at IS NOT NULL AND deleted_at < NOW() - INTERVAL '1 day'",
    )
    .fetch_all(pool)
    .await
    {
        Ok(rows) => rows,
        Err(e) => {
            tracing::warn!(error = ?e, "media reaper: query failed");
            return;
        }
    };

    if rows.is_empty() {
        return;
    }

    let mut ids = Vec::with_capacity(rows.len());
    for (id, original, preview, thumbnail) in &rows {
        unlink_media(media_path, &DeletedPaths {
            original: original.clone(),
            preview: preview.clone(),
            thumbnail: thumbnail.clone(),
        })
        .await;
        ids.push(*id);
    }

    match sqlx::query("DELETE FROM upload WHERE id = ANY($1)")
        .bind(&ids)
        .execute(pool)
        .await
    {
        Ok(r) => tracing::info!("media reaper: removed {} deleted upload(s)", r.rows_affected()),
        Err(e) => tracing::warn!(error = ?e, "media reaper: row delete failed"),
    }
}