use crate::dataframe::values::{Column, NuDataFrame};
use chrono::DateTime;
use nu_engine::command_prelude::*;

use polars::prelude::{IntoSeries, StringMethods, TimeUnit};

#[derive(Clone)]
pub struct AsDateTime;

impl Command for AsDateTime {
    fn name(&self) -> &str {
        "dfr as-datetime"
    }

    fn usage(&self) -> &str {
        r#"Converts string to datetime."#
    }

    fn extra_usage(&self) -> &str {
        r#"Format example:
        "%y/%m/%d %H:%M:%S"  => 21/12/31 12:54:98
        "%y-%m-%d %H:%M:%S"  => 2021-12-31 24:58:01
        "%y/%m/%d %H:%M:%S"  => 21/12/31 24:58:01
        "%y%m%d %H:%M:%S"    => 210319 23:58:50
        "%Y/%m/%d %H:%M:%S"  => 2021/12/31 12:54:98
        "%Y-%m-%d %H:%M:%S"  => 2021-12-31 24:58:01
        "%Y/%m/%d %H:%M:%S"  => 2021/12/31 24:58:01
        "%Y%m%d %H:%M:%S"    => 20210319 23:58:50
        "%FT%H:%M:%S"        => 2019-04-18T02:45:55
        "%FT%H:%M:%S.%6f"    => microseconds
        "%FT%H:%M:%S.%9f"    => nanoseconds"#
    }

    fn signature(&self) -> Signature {
        Signature::build(self.name())
            .required("format", SyntaxShape::String, "formatting date time string")
            .switch("not-exact", "the format string may be contained in the date (e.g. foo-2021-01-01-bar could match 2021-01-01)", Some('n'))
            .input_output_type(
                Type::Custom("dataframe".into()),
                Type::Custom("dataframe".into()),
            )
            .category(Category::Custom("dataframe".into()))
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                description: "Converts string to datetime",
                example: r#"["2021-12-30 00:00:00" "2021-12-31 00:00:00"] | dfr into-df | dfr as-datetime "%Y-%m-%d %H:%M:%S""#,
                result: Some(
                    NuDataFrame::try_from_columns(
                        vec![Column::new(
                            "datetime".to_string(),
                            vec![
                                Value::date(
                                    DateTime::parse_from_str(
                                        "2021-12-30 00:00:00 +0000",
                                        "%Y-%m-%d %H:%M:%S %z",
                                    )
                                    .expect("date calculation should not fail in test"),
                                    Span::test_data(),
                                ),
                                Value::date(
                                    DateTime::parse_from_str(
                                        "2021-12-31 00:00:00 +0000",
                                        "%Y-%m-%d %H:%M:%S %z",
                                    )
                                    .expect("date calculation should not fail in test"),
                                    Span::test_data(),
                                ),
                            ],
                        )],
                        None,
                    )
                    .expect("simple df for test should not fail")
                    .into_value(Span::test_data()),
                ),
            },
            Example {
                description: "Converts string to datetime with high resolutions",
                example: r#"["2021-12-30 00:00:00.123456789" "2021-12-31 00:00:00.123456789"] | dfr into-df | dfr as-datetime "%Y-%m-%d %H:%M:%S.%9f""#,
                result: Some(
                    NuDataFrame::try_from_columns(
                        vec![Column::new(
                            "datetime".to_string(),
                            vec![
                                Value::date(
                                    DateTime::parse_from_str(
                                        "2021-12-30 00:00:00.123456789 +0000",
                                        "%Y-%m-%d %H:%M:%S.%9f %z",
                                    )
                                    .expect("date calculation should not fail in test"),
                                    Span::test_data(),
                                ),
                                Value::date(
                                    DateTime::parse_from_str(
                                        "2021-12-31 00:00:00.123456789 +0000",
                                        "%Y-%m-%d %H:%M:%S.%9f %z",
                                    )
                                    .expect("date calculation should not fail in test"),
                                    Span::test_data(),
                                ),
                            ],
                        )],
                        None,
                    )
                    .expect("simple df for test should not fail")
                    .into_value(Span::test_data()),
                ),
            },
        ]
    }

    fn run(
        &self,
        engine_state: &EngineState,
        stack: &mut Stack,
        call: &Call,
        input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        command(engine_state, stack, call, input)
    }
}

fn command(
    engine_state: &EngineState,
    stack: &mut Stack,
    call: &Call,
    input: PipelineData,
) -> Result<PipelineData, ShellError> {
    let format: String = call.req(engine_state, stack, 0)?;
    let not_exact = call.has_flag(engine_state, stack, "not-exact")?;

    let df = NuDataFrame::try_from_pipeline(input, call.head)?;
    let series = df.as_series(call.head)?;
    let casted = series.str().map_err(|e| ShellError::GenericError {
        error: "Error casting to string".into(),
        msg: e.to_string(),
        span: Some(call.head),
        help: None,
        inner: vec![],
    })?;

    let res = if not_exact {
        casted.as_datetime_not_exact(
            Some(format.as_str()),
            TimeUnit::Nanoseconds,
            false,
            None,
            &Default::default(),
        )
    } else {
        casted.as_datetime(
            Some(format.as_str()),
            TimeUnit::Nanoseconds,
            false,
            false,
            None,
            &Default::default(),
        )
    };

    let mut res = res
        .map_err(|e| ShellError::GenericError {
            error: "Error creating datetime".into(),
            msg: e.to_string(),
            span: Some(call.head),
            help: None,
            inner: vec![],
        })?
        .into_series();

    res.rename("datetime");
    NuDataFrame::try_from_series(vec![res], call.head)
        .map(|df| PipelineData::Value(NuDataFrame::into_value(df, call.head), None))
}

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

    #[test]
    fn test_examples() {
        test_dataframe(vec![Box::new(AsDateTime {})])
    }
}