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use nu_engine::CallExt;

use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
    record, Category, Example, IntoInterruptiblePipelineData, PipelineData, ShellError, Signature,
    SyntaxShape, Type, Value,
};

#[derive(Clone)]
pub struct Drop;

impl Command for Drop {
    fn name(&self) -> &str {
        "drop"
    }

    fn signature(&self) -> Signature {
        Signature::build("drop")
            .input_output_types(vec![
                (Type::Table(vec![]), Type::Table(vec![])),
                (
                    Type::List(Box::new(Type::Any)),
                    Type::List(Box::new(Type::Any)),
                ),
            ])
            .optional("rows", SyntaxShape::Int, "The number of items to remove.")
            .category(Category::Filters)
    }

    fn usage(&self) -> &str {
        "Remove items/rows from the end of the input list/table. Counterpart of `skip`. Opposite of `last`."
    }

    fn search_terms(&self) -> Vec<&str> {
        vec!["delete"]
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                example: "[0,1,2,3] | drop",
                description: "Remove the last item of a list",
                result: Some(Value::test_list(vec![
                    Value::test_int(0),
                    Value::test_int(1),
                    Value::test_int(2),
                ])),
            },
            Example {
                example: "[0,1,2,3] | drop 0",
                description: "Remove zero item of a list",
                result: Some(Value::test_list(vec![
                    Value::test_int(0),
                    Value::test_int(1),
                    Value::test_int(2),
                    Value::test_int(3),
                ])),
            },
            Example {
                example: "[0,1,2,3] | drop 2",
                description: "Remove the last two items of a list",
                result: Some(Value::test_list(vec![
                    Value::test_int(0),
                    Value::test_int(1),
                ])),
            },
            Example {
                description: "Remove the last row in a table",
                example: "[[a, b]; [1, 2] [3, 4]] | drop 1",
                result: Some(Value::test_list(vec![Value::test_record(record! {
                    "a" =>  Value::test_int(1),
                    "b" =>  Value::test_int(2),
                })])),
            },
        ]
    }

    fn run(
        &self,
        engine_state: &EngineState,
        stack: &mut Stack,
        call: &Call,
        input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        let metadata = input.metadata();
        let rows: Option<i64> = call.opt(engine_state, stack, 0)?;
        let v: Vec<_> = input.into_iter_strict(call.head)?.collect();
        let vlen: i64 = v.len() as i64;

        let rows_to_drop = if let Some(quantity) = rows {
            quantity
        } else {
            1
        };

        if rows_to_drop == 0 {
            Ok(v.into_iter()
                .into_pipeline_data_with_metadata(metadata, engine_state.ctrlc.clone()))
        } else {
            let k = if vlen < rows_to_drop {
                0
            } else {
                vlen - rows_to_drop
            };

            let iter = v.into_iter().take(k as usize);
            Ok(iter.into_pipeline_data_with_metadata(metadata, engine_state.ctrlc.clone()))
        }
    }
}

#[cfg(test)]
mod test {
    use crate::Drop;

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

        test_examples(Drop {})
    }
}