// file: kb_lib/src/db/queries/db_metadata.rs

//! Queries for `kb_db_metadata`.

/// Inserts or updates one metadata row.
pub async fn upsert_db_metadata(
    database: &crate::KbDatabase,
    dto: &crate::KbDbMetadataDto,
) -> Result<(), crate::KbError> {
    let entity = crate::KbDbMetadataEntity::from(dto.clone());
    match database.connection() {
        crate::KbDatabaseConnection::Sqlite(pool) => {
            let query_result = sqlx::query(
                r#"
INSERT INTO kb_db_metadata (
    key,
    value,
    updated_at
)
VALUES (?, ?, ?)
ON CONFLICT(key) DO UPDATE SET
    value = excluded.value,
    updated_at = excluded.updated_at
                "#,
            )
            .bind(entity.key)
            .bind(entity.value)
            .bind(entity.updated_at)
            .execute(pool)
            .await;
            match query_result {
                Ok(_) => return Ok(()),
                Err(error) => {
                    return Err(crate::KbError::Db(format!(
                        "cannot upsert kb_db_metadata on sqlite: {}",
                        error
                    )));
                },
            }
        },
    }
}

/// Reads one metadata row by key.
pub async fn get_db_metadata(
    database: &crate::KbDatabase,
    key: &str,
) -> Result<std::option::Option<crate::KbDbMetadataDto>, crate::KbError> {
    match database.connection() {
        crate::KbDatabaseConnection::Sqlite(pool) => {
            let query_result = sqlx::query_as::<sqlx::Sqlite, crate::KbDbMetadataEntity>(
                r#"
SELECT
    key,
    value,
    updated_at
FROM kb_db_metadata
WHERE key = ?
LIMIT 1
                "#,
            )
            .bind(key)
            .fetch_optional(pool)
            .await;
            let entity_option = match query_result {
                Ok(entity_option) => entity_option,
                Err(error) => {
                    return Err(crate::KbError::Db(format!(
                        "cannot read kb_db_metadata '{}' on sqlite: {}",
                        key, error
                    )));
                },
            };
            match entity_option {
                Some(entity) => {
                    let dto_result = crate::KbDbMetadataDto::try_from(entity);
                    match dto_result {
                        Ok(dto) => return Ok(Some(dto)),
                        Err(error) => return Err(error),
                    }
                },
                None => return Ok(None),
            }
        },
    }
}

/// Lists all metadata rows.
pub async fn list_db_metadata(
    database: &crate::KbDatabase,
) -> Result<std::vec::Vec<crate::KbDbMetadataDto>, crate::KbError> {
    match database.connection() {
        crate::KbDatabaseConnection::Sqlite(pool) => {
            let query_result = sqlx::query_as::<sqlx::Sqlite, crate::KbDbMetadataEntity>(
                r#"
SELECT
    key,
    value,
    updated_at
FROM kb_db_metadata
ORDER BY key ASC
                "#,
            )
            .fetch_all(pool)
            .await;
            let entities = match query_result {
                Ok(entities) => entities,
                Err(error) => {
                    return Err(crate::KbError::Db(format!(
                        "cannot list kb_db_metadata on sqlite: {}",
                        error
                    )));
                },
            };
            let mut dtos = std::vec::Vec::new();
            for entity in entities {
                let dto_result = crate::KbDbMetadataDto::try_from(entity);
                let dto = match dto_result {
                    Ok(dto) => dto,
                    Err(error) => return Err(error),
                };
                dtos.push(dto);
            }
            return Ok(dtos);
        },
    }
}

#[cfg(test)]
mod tests {
    #[tokio::test]
    async fn db_metadata_roundtrip_works() {
        let tempdir = tempfile::tempdir().expect("tempdir must succeed");
        let database_path = tempdir.path().join("roundtrip.sqlite3");
        let config = crate::KbDatabaseConfig {
            enabled: true,
            backend: crate::KbDatabaseBackend::Sqlite,
            sqlite: crate::KbSqliteDatabaseConfig {
                path: database_path.to_string_lossy().to_string(),
                create_if_missing: true,
                busy_timeout_ms: 5000,
                max_connections: 1,
                auto_initialize_schema: true,
                use_wal: true,
            },
        };
        let database = crate::KbDatabase::connect_and_initialize(&config)
            .await
            .expect("database init must succeed");
        let dto = crate::KbDbMetadataDto::new("schema_version".to_string(), "0.5.0".to_string());
        crate::upsert_db_metadata(&database, &dto).await.expect("upsert must succeed");
        let fetched = crate::get_db_metadata(&database, "schema_version")
            .await
            .expect("fetch must succeed");
        assert!(fetched.is_some());
        let fetched = fetched.expect("metadata must exist");
        assert_eq!(fetched.key, "schema_version");
        assert_eq!(fetched.value, "0.5.0");
        let listed = crate::list_db_metadata(&database).await.expect("list must succeed");
        assert!(!listed.is_empty());
    }
}