use crate::{
    PolarsPlugin,
    dataframe::values::NuExpression,
    values::{CustomValueSupport, PolarsPluginType},
};
use nu_plugin::{EngineInterface, EvaluatedCall, PluginCommand};
use nu_protocol::{
    Category, Example, LabeledError, PipelineData, Signature, SyntaxShape, Type, Value, record,
};

#[derive(Clone)]
pub struct ExprLit;

impl PluginCommand for ExprLit {
    type Plugin = PolarsPlugin;

    fn name(&self) -> &str {
        "polars lit"
    }

    fn description(&self) -> &str {
        "Creates a literal expression."
    }

    fn signature(&self) -> Signature {
        Signature::build(self.name())
            .required(
                "literal",
                SyntaxShape::Any,
                "Literal to construct the expression.",
            )
            .input_output_type(Type::Any, PolarsPluginType::NuExpression.into())
            .category(Category::Custom("expression".into()))
    }

    fn examples(&self) -> Vec<Example<'_>> {
        vec![
            Example {
                description: "Created a literal expression and converts it to a nu object",
                example: "polars lit 2 | polars into-nu",
                result: Some(Value::test_record(record! {
                    "expr" =>  Value::test_string("literal"),
                    "value" => Value::test_string("dyn int: 2"),
                })),
            },
            Example {
                description: "Create a literal expression from date",
                example: "polars lit 2025-04-13 | polars into-nu",
                result: Some(Value::test_record(record! {
                    "expr" => Value::test_record(record! {
                        "expr" =>  Value::test_string("literal"),
                        "value" => Value::test_string("dyn int: 1744502400000000000"),
                    }),
                    "dtype" => Value::test_string("Datetime('ns')"),
                    "cast_options" => Value::test_string("STRICT")
                })),
            },
            Example {
                description: "Create a literal expression from duration",
                example: "polars lit 3hr | polars into-nu",
                result: Some(Value::test_record(record! {
                    "expr" => Value::test_record(record! {
                        "expr" =>  Value::test_string("literal"),
                        "value" => Value::test_string("dyn int: 10800000000000"),
                    }),
                    "dtype" => Value::test_string("Duration('ns')"),
                    "cast_options" => Value::test_string("STRICT")
                })),
            },
        ]
    }

    fn search_terms(&self) -> Vec<&str> {
        vec!["string", "literal", "expression"]
    }

    fn run(
        &self,
        plugin: &Self::Plugin,
        engine: &EngineInterface,
        call: &EvaluatedCall,
        _input: PipelineData,
    ) -> Result<PipelineData, LabeledError> {
        let literal: Value = call.req(0)?;
        let expr = NuExpression::try_from_value(plugin, &literal)?;
        expr.to_pipeline_data(plugin, engine, call.head)
            .map_err(LabeledError::from)
    }
}

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

    #[test]
    fn test_examples() -> Result<(), nu_protocol::ShellError> {
        test_polars_plugin_command(&ExprLit)
    }
}
