#![feature(box_patterns, box_syntax, proc_macro_hygiene, decl_macro, iter_intersperse)]
#![feature(plugin)]

#[macro_use]
extern crate serde_derive;
extern crate includedir;
extern crate phf;
extern crate serde_json;

mod command_tree;
mod language;
use self::command_tree::CommandTree;
mod repl_options;
use repl_options::ReplOptions;
mod directive_actions;
mod directives;
use directives::directives_from_pass_names;
mod help;
mod response;
use std::{collections::HashSet, sync::Arc};

use colored::*;
pub use language::{
    ComputationRequest, ComputationResponse, DebugAsk, DebugResponse, GlobalOutputStats, LangMetaRequest,
    LangMetaResponse, ProgrammingLanguageInterface,
};
use response::ReplResponse;

include!(concat!(env!("OUT_DIR"), "/static.rs"));
const VERSION_STRING: &str = "0.1.0";

const HISTORY_SAVE_FILE: &str = ".schala_history";
const OPTIONS_SAVE_FILE: &str = ".schala_repl";

type InterpreterDirectiveOutput = Option<String>;

pub struct Repl<L: ProgrammingLanguageInterface> {
    /// If this is the first character typed by a user into the repl, the following
    /// will be interpreted as a directive to the REPL rather than a command in the
    /// running programming language.
    sigil: char,
    line_reader: ::linefeed::interface::Interface<::linefeed::terminal::DefaultTerminal>,
    language_state: L,
    options: ReplOptions,
}

#[derive(Clone)]
enum PromptStyle {
    Normal,
    Multiline,
}

impl<L: ProgrammingLanguageInterface> Repl<L> {
    pub fn new(initial_state: L) -> Self {
        use linefeed::Interface;
        let line_reader = Interface::new("schala-repl").unwrap();
        let sigil = ':';

        Repl { sigil, line_reader, language_state: initial_state, options: ReplOptions::new() }
    }

    pub fn run_repl(&mut self, config: L::Config) {
        println!("Schala meta-interpeter version {}", VERSION_STRING);
        println!("Type {} for help with the REPL", format!("{}help", self.sigil).bright_green().bold());
        self.load_options();
        self.handle_repl_loop(config);
        self.save_before_exit();
        println!("Exiting...");
    }

    fn load_options(&mut self) {
        self.line_reader.load_history(HISTORY_SAVE_FILE).unwrap_or(());
        match ReplOptions::load_from_file(OPTIONS_SAVE_FILE) {
            Ok(options) => {
                self.options = options;
            }
            Err(e) => eprintln!("{}", e),
        }
    }

    fn handle_repl_loop(&mut self, config: L::Config) {
        use linefeed::ReadResult::*;

        'main: loop {
            macro_rules! match_or_break {
                ($line:expr) => {
                    match $line {
                        Err(e) => {
                            println!("readline IO Error: {}", e);
                            break 'main;
                        }
                        Ok(Eof) | Ok(Signal(_)) => break 'main,
                        Ok(Input(ref input)) => input,
                    }
                };
            }
            self.update_line_reader();
            let line = self.line_reader.read_line();
            let input: &str = match_or_break!(line);

            self.line_reader.add_history_unique(input.to_string());
            let mut chars = input.chars().peekable();
            let repl_responses = match chars.next() {
                Some(ch) if ch == self.sigil =>
                    if chars.peek() == Some(&'{') {
                        let mut buf = String::new();
                        buf.push_str(input.get(2..).unwrap());
                        'multiline: loop {
                            self.set_prompt(PromptStyle::Multiline);
                            let new_line = self.line_reader.read_line();
                            let new_input = match_or_break!(new_line);
                            if new_input.starts_with(":}") {
                                break 'multiline;
                            } else {
                                buf.push_str(new_input);
                                buf.push('\n');
                            }
                        }
                        self.handle_input(&buf, &config)
                    } else {
                        if let Some(output) = self.handle_interpreter_directive(input.get(1..).unwrap()) {
                            println!("{}", output);
                        }
                        continue;
                    },
                _ => self.handle_input(input, &config),
            };

            for repl_response in repl_responses.iter() {
                println!("{}", repl_response);
            }
        }
    }

    fn update_line_reader(&mut self) {
        let tab_complete_handler = TabCompleteHandler::new(self.sigil, self.get_directives());
        self.line_reader.set_completer(Arc::new(tab_complete_handler)); //TODO fix this here
        self.set_prompt(PromptStyle::Normal);
    }

    fn set_prompt(&mut self, prompt_style: PromptStyle) {
        let prompt_str = match prompt_style {
            PromptStyle::Normal => ">> ",
            PromptStyle::Multiline => ">| ",
        };

        self.line_reader.set_prompt(prompt_str).unwrap();
    }

    fn save_before_exit(&self) {
        self.line_reader.save_history(HISTORY_SAVE_FILE).unwrap_or(());
        self.options.save_to_file(OPTIONS_SAVE_FILE);
    }

    fn handle_interpreter_directive(&mut self, input: &str) -> InterpreterDirectiveOutput {
        let arguments: Vec<&str> = input.split_whitespace().collect();

        if arguments.is_empty() {
            return None;
        }

        let directives = self.get_directives();
        directives.perform(self, &arguments)
    }

    fn handle_input(&mut self, input: &str, config: &L::Config) -> Vec<ReplResponse> {
        let mut debug_requests = HashSet::new();
        for ask in self.options.debug_asks.iter() {
            debug_requests.insert(ask.clone());
        }

        let request = ComputationRequest { source: input, config: config.clone(), debug_requests };
        let response = self.language_state.run_computation(request);
        response::handle_computation_response(response, &self.options)
    }

    fn get_directives(&mut self) -> CommandTree {
        let pass_names = match self.language_state.request_meta(LangMetaRequest::StageNames) {
            LangMetaResponse::StageNames(names) => names,
            _ => vec![],
        };

        directives_from_pass_names(&pass_names)
    }
}

struct TabCompleteHandler {
    sigil: char,
    top_level_commands: CommandTree,
}

use linefeed::{
    complete::{Completer, Completion},
    terminal::Terminal,
};

impl TabCompleteHandler {
    fn new(sigil: char, top_level_commands: CommandTree) -> TabCompleteHandler {
        TabCompleteHandler { top_level_commands, sigil }
    }
}

impl<T: Terminal> Completer<T> for TabCompleteHandler {
    fn complete(
        &self,
        word: &str,
        prompter: &::linefeed::prompter::Prompter<T>,
        start: usize,
        _end: usize,
    ) -> Option<Vec<Completion>> {
        let line = prompter.buffer();

        if !line.starts_with(self.sigil) {
            return None;
        }

        let mut words = line[1..(if start == 0 { 1 } else { start })].split_whitespace();
        let mut completions = Vec::new();
        let mut command_tree: Option<&CommandTree> = Some(&self.top_level_commands);

        loop {
            match words.next() {
                None => {
                    let top = matches!(command_tree, Some(CommandTree::Top(_)));
                    let word = if top { word.get(1..).unwrap() } else { word };
                    for cmd in command_tree.map(|x| x.get_subcommands()).unwrap_or_default().into_iter() {
                        if cmd.starts_with(word) {
                            completions.push(Completion {
                                completion: format!("{}{}", if top { ":" } else { "" }, cmd),
                                display: Some(cmd.to_string()),
                                suffix: ::linefeed::complete::Suffix::Some(' '),
                            })
                        }
                    }
                    break;
                }
                Some(s) => {
                    let new_ptr: Option<&CommandTree> = command_tree.and_then(|cm| match cm {
                        CommandTree::Top(children) => children.iter().find(|c| c.get_cmd() == s),
                        CommandTree::NonTerminal { children, .. } =>
                            children.iter().find(|c| c.get_cmd() == s),
                        CommandTree::Terminal { children, .. } => children.iter().find(|c| c.get_cmd() == s),
                    });
                    command_tree = new_ptr;
                }
            }
        }
        Some(completions)
    }
}