use chrono_humanize::HumanTime;
use nu_protocol::{
    ast::Call,
    engine::{Command, EngineState, Stack},
    format_duration, format_filesize_from_conf, Category, Config, Example, IntoPipelineData,
    ListStream, PipelineData, RawStream, ShellError, Signature, Type, Value,
};

#[derive(Clone)]
pub struct ToText;

impl Command for ToText {
    fn name(&self) -> &str {
        "to text"
    }

    fn signature(&self) -> Signature {
        Signature::build("to text")
            .input_output_types(vec![(Type::Any, Type::String)])
            .category(Category::Formats)
    }

    fn usage(&self) -> &str {
        "Converts data into simple text."
    }

    fn run(
        &self,
        engine_state: &EngineState,
        _stack: &mut Stack,
        call: &Call,
        input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        let span = call.head;
        let config = engine_state.get_config();

        let line_ending = if cfg!(target_os = "windows") {
            "\r\n"
        } else {
            "\n"
        };
        let input = input.try_expand_range()?;

        if let PipelineData::ListStream(stream, _) = input {
            Ok(PipelineData::ExternalStream {
                stdout: Some(RawStream::new(
                    Box::new(ListStreamIterator {
                        stream,
                        separator: line_ending.into(),
                        config: config.clone(),
                    }),
                    engine_state.ctrlc.clone(),
                    span,
                    None,
                )),
                stderr: None,
                exit_code: None,
                span,
                metadata: None,
                trim_end_newline: false,
            })
        } else {
            // FIXME: don't collect! stream the output wherever possible!
            // Even if the data is collected when it arrives at `to text`, we should be able to stream it out
            let collected_input = local_into_string(input.into_value(span), line_ending, config);

            Ok(Value::string(collected_input, span).into_pipeline_data())
        }
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                description: "Outputs data as simple text",
                example: "1 | to text",
                result: Some(Value::test_string("1")),
            },
            Example {
                description: "Outputs external data as simple text",
                example: "git help -a | lines | find -r '^ ' | to text",
                result: None,
            },
            Example {
                description: "Outputs records as simple text",
                example: "ls | to text",
                result: None,
            },
        ]
    }
}

struct ListStreamIterator {
    stream: ListStream,
    separator: String,
    config: Config,
}

impl Iterator for ListStreamIterator {
    type Item = Result<Vec<u8>, ShellError>;

    fn next(&mut self) -> Option<Self::Item> {
        if let Some(item) = self.stream.next() {
            let mut string = local_into_string(item, &self.separator, &self.config);
            string.push_str(&self.separator);
            Some(Ok(string.as_bytes().to_vec()))
        } else {
            None
        }
    }
}

fn local_into_string(value: Value, separator: &str, config: &Config) -> String {
    match value {
        Value::Bool { val, .. } => val.to_string(),
        Value::Int { val, .. } => val.to_string(),
        Value::Float { val, .. } => val.to_string(),
        Value::Filesize { val, .. } => format_filesize_from_conf(val, config),
        Value::Duration { val, .. } => format_duration(val),
        Value::Date { val, .. } => {
            format!("{} ({})", val.to_rfc2822(), HumanTime::from(val))
        }
        Value::Range { val, .. } => {
            format!(
                "{}..{}",
                local_into_string(val.from, ", ", config),
                local_into_string(val.to, ", ", config)
            )
        }
        Value::String { val, .. } => val,
        Value::List { vals: val, .. } => val
            .into_iter()
            .map(|x| local_into_string(x, ", ", config))
            .collect::<Vec<_>>()
            .join(separator),
        Value::Record { val, .. } => val
            .into_iter()
            .map(|(x, y)| format!("{}: {}", x, local_into_string(y, ", ", config)))
            .collect::<Vec<_>>()
            .join(separator),
        Value::LazyRecord { val, .. } => match val.collect() {
            Ok(val) => local_into_string(val, separator, config),
            Err(error) => format!("{error:?}"),
        },
        Value::Block { val, .. } => format!("<Block {val}>"),
        Value::Closure { val, .. } => format!("<Closure {val}>"),
        Value::Nothing { .. } => String::new(),
        Value::Error { error, .. } => format!("{error:?}"),
        Value::Binary { val, .. } => format!("{val:?}"),
        Value::CellPath { val, .. } => val.into_string(),
        Value::CustomValue { val, .. } => val.value_string(),
        Value::MatchPattern { val, .. } => format!("{:?}", val),
    }
}

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

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

        test_examples(ToText {})
    }
}