use nu_engine::command_prelude::*;
use std::process::{Command as CommandSys, Stdio};

#[derive(Clone)]
pub struct Kill;

impl Command for Kill {
    fn name(&self) -> &str {
        "kill"
    }

    fn description(&self) -> &str {
        "Kill a process using the process id."
    }

    fn signature(&self) -> Signature {
        let signature = Signature::build("kill")
            .input_output_types(vec![(Type::Nothing, Type::Any)])
            .allow_variants_without_examples(true)
            .required(
                "pid",
                SyntaxShape::Int,
                "Process id of process that is to be killed.",
            )
            .rest("rest", SyntaxShape::Int, "Rest of processes to kill.")
            .switch("force", "forcefully kill the process", Some('f'))
            .switch("quiet", "won't print anything to the console", Some('q'))
            .category(Category::Platform);

        if cfg!(windows) {
            return signature;
        }

        signature.named(
            "signal",
            SyntaxShape::Int,
            "signal decimal number to be sent instead of the default 15 (unsupported on Windows)",
            Some('s'),
        )
    }

    fn search_terms(&self) -> Vec<&str> {
        vec!["stop", "end", "close"]
    }

    fn run(
        &self,
        engine_state: &EngineState,
        stack: &mut Stack,
        call: &Call,
        _input: PipelineData,
    ) -> Result<PipelineData, ShellError> {
        let pid: i64 = call.req(engine_state, stack, 0)?;
        let rest: Vec<i64> = call.rest(engine_state, stack, 1)?;
        let force: bool = call.has_flag(engine_state, stack, "force")?;
        let signal: Option<Spanned<i64>> = call.get_flag(engine_state, stack, "signal")?;
        let quiet: bool = call.has_flag(engine_state, stack, "quiet")?;

        let mut cmd = if cfg!(windows) {
            let mut cmd = CommandSys::new("taskkill");

            if force {
                cmd.arg("/F");
            }

            cmd.arg("/PID");
            cmd.arg(pid.to_string());

            // each pid must written as `/PID 0` otherwise
            // taskkill will act as `killall` unix command
            for id in &rest {
                cmd.arg("/PID");
                cmd.arg(id.to_string());
            }

            cmd
        } else {
            let mut cmd = CommandSys::new("kill");
            if force {
                if let Some(Spanned {
                    item: _,
                    span: signal_span,
                }) = signal
                {
                    return Err(ShellError::IncompatibleParameters {
                        left_message: "force".to_string(),
                        left_span: call.get_flag_span(stack, "force").ok_or_else(|| {
                            ShellError::GenericError {
                                error: "Flag error".into(),
                                msg: "flag force not found".into(),
                                span: Some(call.head),
                                help: None,
                                inner: vec![],
                            }
                        })?,
                        right_message: "signal".to_string(),
                        right_span: Span::merge(
                            call.get_flag_span(stack, "signal").ok_or_else(|| {
                                ShellError::GenericError {
                                    error: "Flag error".into(),
                                    msg: "flag signal not found".into(),
                                    span: Some(call.head),
                                    help: None,
                                    inner: vec![],
                                }
                            })?,
                            signal_span,
                        ),
                    });
                }
                cmd.arg("-9");
            } else if let Some(signal_value) = signal {
                cmd.arg(format!("-{}", signal_value.item));
            }

            cmd.arg(pid.to_string());

            cmd.args(rest.iter().map(move |id| id.to_string()));

            cmd
        };

        // pipe everything to null
        if quiet {
            cmd.stdin(Stdio::null())
                .stdout(Stdio::null())
                .stderr(Stdio::null());
        }

        let output = cmd.output().map_err(|e| ShellError::GenericError {
            error: "failed to execute shell command".into(),
            msg: e.to_string(),
            span: Some(call.head),
            help: None,
            inner: vec![],
        })?;

        if !quiet && !output.status.success() {
            return Err(ShellError::GenericError {
                error: "process didn't terminate successfully".into(),
                msg: String::from_utf8(output.stderr).unwrap_or_default(),
                span: Some(call.head),
                help: None,
                inner: vec![],
            });
        }

        let mut output =
            String::from_utf8(output.stdout).map_err(|e| ShellError::GenericError {
                error: "failed to convert output to string".into(),
                msg: e.to_string(),
                span: Some(call.head),
                help: None,
                inner: vec![],
            })?;

        output.truncate(output.trim_end().len());

        if output.is_empty() {
            Ok(Value::nothing(call.head).into_pipeline_data())
        } else {
            Ok(Value::string(output, call.head).into_pipeline_data())
        }
    }

    fn examples(&self) -> Vec<Example> {
        vec![
            Example {
                description: "Kill the pid using the most memory",
                example: "ps | sort-by mem | last | kill $in.pid",
                result: None,
            },
            Example {
                description: "Force kill a given pid",
                example: "kill --force 12345",
                result: None,
            },
            #[cfg(not(target_os = "windows"))]
            Example {
                description: "Send INT signal",
                example: "kill -s 2 12345",
                result: None,
            },
        ]
    }
}

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

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