delete.rs

use crate::database::{SQLiteDatabase, MEMORY_DB};
use nu_engine::command_prelude::*;

#[derive(Clone)]
pub struct StorDelete;

impl Command for StorDelete {
    fn name(&self) -> &str {
        "stor delete"
    }

    fn signature(&self) -> Signature {
        Signature::build("stor delete")
            .input_output_types(vec![(Type::Nothing, Type::Table(vec![]))])
            .required_named(
                "table-name",
                SyntaxShape::String,
                "name of the table you want to insert into",
                Some('t'),
            )
            .named(
                "where-clause",
                SyntaxShape::String,
                "a sql string to use as a where clause without the WHERE keyword",
                Some('w'),
            )
            .allow_variants_without_examples(true)
            .category(Category::Database)
    }

    fn usage(&self) -> &str {
        "Delete a table or specified rows in the in-memory sqlite database."
    }

    fn search_terms(&self) -> Vec<&str> {
        vec!["sqlite", "remove", "table", "saving", "drop"]
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                description: "Delete a table from the in-memory sqlite database",
                example: "stor delete --table-name nudb",
                result: None,
            },
            Example {
                description:
                    "Delete some rows from the in-memory sqlite database with a where clause",
                example: "stor delete --table-name nudb --where-clause \"int1 == 5\"",
                result: None,
            },
        ]
    }

    fn run(
        &self,
        engine_state: &EngineState,
        stack: &mut Stack,
        call: &Call,
        _input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        let span = call.head;
        // For dropping/deleting an entire table
        let table_name_opt: Option<String> = call.get_flag(engine_state, stack, "table-name")?;

        // For deleting rows from a table
        let where_clause_opt: Option<String> =
            call.get_flag(engine_state, stack, "where-clause")?;

        if table_name_opt.is_none() && where_clause_opt.is_none() {
            return Err(ShellError::MissingParameter {
                param_name: "requires at least one of table-name or where-clause".into(),
                span,
            });
        }

        if table_name_opt.is_none() && where_clause_opt.is_some() {
            return Err(ShellError::MissingParameter {
                param_name: "using the where-clause requires the use of a table-name".into(),
                span,
            });
        }

        // Open the in-mem database
        let db = Box::new(SQLiteDatabase::new(std::path::Path::new(MEMORY_DB), None));

        if let Some(new_table_name) = table_name_opt {
            if let Ok(conn) = db.open_connection() {
                let sql_stmt = match where_clause_opt {
                    None => {
                        // We're deleting an entire table
                        format!("DROP TABLE {}", new_table_name)
                    }
                    Some(where_clause) => {
                        // We're just deleting some rows
                        let mut delete_stmt = format!("DELETE FROM {} ", new_table_name);

                        // Yup, this is a bit janky, but I'm not sure a better way to do this without having
                        // --and and --or flags as well as supporting ==, !=, <>, is null, is not null, etc.
                        // and other sql syntax. So, for now, just type a sql where clause as a string.
                        delete_stmt.push_str(&format!("WHERE {}", where_clause));
                        delete_stmt
                    }
                };

                // dbg!(&sql_stmt);
                conn.execute(&sql_stmt, [])
                    .map_err(|err| ShellError::GenericError {
                        error: "Failed to open SQLite connection in memory from delete".into(),
                        msg: err.to_string(),
                        span: Some(Span::test_data()),
                        help: None,
                        inner: vec![],
                    })?;
            }
        }
        // dbg!(db.clone());
        Ok(Value::custom(db, span).into_pipeline_data())
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn test_examples() {
        use crate::test_examples;

        test_examples(StorDelete {})
    }
}