//! 미디어 서버용 file_id → 경로/원격스트림 리졸버 (DB 조회 + VFS).

use crate::remote::RemotePool;
use archive_db::Db;
use archive_media::RemoteStream;
use std::path::PathBuf;
use std::sync::Arc;

pub struct DbResolver {
    pub db: Arc<Db>,
    pub thumb_root: PathBuf,
    pub remote: Arc<RemotePool>,
}

struct FileLoc {
    kind: String, // sources.kind
    source_id: i64,
    dir: String,
    name: String,
    size: i64,
}

impl DbResolver {
    fn locate(&self, file_id: i64) -> Option<FileLoc> {
        self.db
            .with_read(|conn| {
                conn.query_row(
                    "SELECT s.kind, f.source_id, fo.path, f.name, f.size
                     FROM files f
                     JOIN folders fo ON fo.id = f.folder_id
                     JOIN sources s ON s.id = f.source_id
                     WHERE f.id = ?1 AND f.deleted_at IS NULL",
                    [file_id],
                    |r| {
                        Ok(FileLoc {
                            kind: r.get(0)?,
                            source_id: r.get(1)?,
                            dir: r.get(2)?,
                            name: r.get(3)?,
                            size: r.get(4)?,
                        })
                    },
                )
            })
            .ok()
    }
}

#[async_trait::async_trait]
impl archive_media::PathResolver for DbResolver {
    fn resolve(&self, file_id: i64) -> Option<PathBuf> {
        let loc = self.locate(file_id)?;
        if loc.kind != "local" {
            return None;
        }
        Some(PathBuf::from(loc.dir).join(loc.name))
    }

    fn resolve_thumb(&self, file_id: i64, size_class: u8) -> Option<PathBuf> {
        let key: String = self
            .db
            .with_read(|conn| {
                conn.query_row(
                    "SELECT cache_key FROM thumbs WHERE file_id = ?1 AND size_class = ?2",
                    rusqlite::params![file_id, size_class],
                    |r| r.get(0),
                )
            })
            .ok()?;
        let path = archive_indexer::thumbq::thumb_path(&self.thumb_root, size_class, &key);
        path.exists().then_some(path)
    }

    fn is_remote(&self, file_id: i64) -> bool {
        self.locate(file_id).map(|l| l.kind != "local").unwrap_or(false)
    }

    async fn open_remote(
        &self,
        file_id: i64,
        range: Option<std::ops::Range<u64>>,
    ) -> Option<RemoteStream> {
        let loc = self.locate(file_id)?;
        let provider = self.remote.get(loc.source_id).await?;
        // 원격 상대 경로: 폴더 path + name (루트는 빈 문자열)
        let rel = if loc.dir == "/" || loc.dir.is_empty() {
            loc.name.clone()
        } else {
            format!("{}/{}", loc.dir.trim_start_matches('/'), loc.name)
        };
        let mime = mime_guess::from_path(&loc.name).first_or_octet_stream().to_string();

        // 0바이트 요청(HEAD 격)이면 길이만 반환
        if let Some(r) = &range {
            if r.start == 0 && r.end == 0 {
                return Some(RemoteStream {
                    total_len: loc.size.max(0) as u64,
                    reader: Box::new(tokio::io::empty()),
                    mime,
                });
            }
        }

        let reader = provider.open_range(&rel, range).await.ok()?;
        Some(RemoteStream {
            total_len: loc.size.max(0) as u64,
            reader,
            mime,
        })
    }
}