use crate::help::help;
use crate::language::{
    DebugAsk, DebugResponse, LangMetaRequest, LangMetaResponse, ProgrammingLanguageInterface,
};
use crate::{InterpreterDirectiveOutput, Repl};
use std::fmt::Write as FmtWrite;

#[derive(Debug, Clone)]
pub enum DirectiveAction {
    Null,
    Help,
    QuitProgram,
    ListPasses,
    ShowImmediate,
    Show,
    Hide,
    TotalTimeOff,
    TotalTimeOn,
    StageTimeOff,
    StageTimeOn,
    Doc,
}

impl DirectiveAction {
    pub fn perform<L: ProgrammingLanguageInterface>(
        &self,
        repl: &mut Repl<L>,
        arguments: &[&str],
    ) -> InterpreterDirectiveOutput {
        use DirectiveAction::*;
        match self {
            Null => None,
            Help => help(repl, arguments),
            QuitProgram => {
                repl.save_before_exit();
                ::std::process::exit(0)
            }
            ListPasses => {
                let pass_names = match repl
                    .language_state
                    .request_meta(LangMetaRequest::StageNames)
                {
                    LangMetaResponse::StageNames(names) => names,
                    _ => vec![],
                };

                let mut buf = String::new();
                for pass in pass_names.iter().map(|name| Some(name)).intersperse(None) {
                    match pass {
                        Some(pass) => write!(buf, "{}", pass).unwrap(),
                        None => write!(buf, " -> ").unwrap(),
                    }
                }
                Some(buf)
            }
            ShowImmediate => {
                let stage_name = match arguments.get(0) {
                    Some(s) => s.to_string(),
                    None => return Some(format!("Must specify a thing to debug")),
                };
                let meta = LangMetaRequest::ImmediateDebug(DebugAsk::ByStage {
                    stage_name: stage_name.clone(),
                    token: None,
                });
                let meta_response = repl.language_state.request_meta(meta);

                let response = match meta_response {
                    LangMetaResponse::ImmediateDebug(DebugResponse { ask, value }) => match ask {
                        DebugAsk::ByStage {
                            stage_name: ref this_stage_name,
                            ..
                        } if *this_stage_name == stage_name => value,
                        _ => return Some(format!("Wrong debug stage")),
                    },
                    _ => return Some(format!("Invalid language meta response")),
                };
                Some(response)
            }
            Show => {
                let this_stage_name = match arguments.get(0) {
                    Some(s) => s.to_string(),
                    None => return Some(format!("Must specify a stage to show")),
                };
                let token = arguments.get(1).map(|s| s.to_string());
                repl.options.debug_asks.retain(|ask| match ask {
                    DebugAsk::ByStage { stage_name, .. } if *stage_name == this_stage_name => false,
                    _ => true,
                });

                let ask = DebugAsk::ByStage {
                    stage_name: this_stage_name,
                    token,
                };
                repl.options.debug_asks.insert(ask);
                None
            }
            Hide => {
                let stage_name_to_remove = match arguments.get(0) {
                    Some(s) => s.to_string(),
                    None => return Some(format!("Must specify a stage to hide")),
                };
                repl.options.debug_asks.retain(|ask| match ask {
                    DebugAsk::ByStage { stage_name, .. } if *stage_name == stage_name_to_remove => {
                        false
                    }
                    _ => true,
                });
                None
            }
            TotalTimeOff => {
                repl.options.show_total_time = false;
                None
            }
            TotalTimeOn => {
                repl.options.show_total_time = true;
                None
            }
            StageTimeOff => {
                repl.options.show_stage_times = false;
                None
            }
            StageTimeOn => {
                repl.options.show_stage_times = true;
                None
            }
            Doc => doc(repl, arguments),
        }
    }
}

fn doc<L: ProgrammingLanguageInterface>(
    repl: &mut Repl<L>,
    arguments: &[&str],
) -> InterpreterDirectiveOutput {
    arguments
        .get(0)
        .map(|cmd| {
            let source = cmd.to_string();
            let meta = LangMetaRequest::Docs { source };
            match repl.language_state.request_meta(meta) {
                LangMetaResponse::Docs { doc_string } => Some(doc_string),
                _ => Some(format!("Invalid doc response")),
            }
        })
        .unwrap_or(Some(format!(":docs needs an argument")))
}