#![feature(advanced_slice_patterns, slice_patterns, box_patterns)]
extern crate getopts;
extern crate linefeed;

use std::path::Path;
use std::fs::File;
use std::io::Read;
use std::process;
use std::io::Write;
use std::default::Default;

mod schala_lang;
mod maaru_lang;
mod robo_lang;

mod language;
use language::{ProgrammingLanguageInterface, EvalOptions, LLVMCodeString};

mod llvm_wrap;

mod virtual_machine;
use virtual_machine::{run_vm, run_assembler};

fn main() {
  let languages: Vec<Box<ProgrammingLanguageInterface>> =
    vec![
      Box::new(schala_lang::Schala::new()),
      Box::new(maaru_lang::Maaru::new()),
      Box::new(robo_lang::Robo::new()),
    ];

  let option_matches =
    match program_options().parse(std::env::args()) {
      Ok(o) => o,
      Err(e) => {
        println!("{:?}", e);
        std::process::exit(1);
      }
    };
  if option_matches.opt_present("list-languages") {
    for lang in languages {
      println!("{}", lang.get_language_name());
    }
    std::process::exit(1);
  }

  if option_matches.opt_present("h") {
    println!("{}", program_options().usage("Schala metainterpreter"));
    std::process::exit(0);
  }

  if option_matches.opt_present("m") {
    let file_name = option_matches.free.get(1);
    run_vm(file_name);
    std::process::exit(0);
  }

  if option_matches.opt_present("a") {
    let file_name = option_matches.free.get(1);
    run_assembler(file_name);
    std::process::exit(0);
  }

  let language_names: Vec<String> = languages.iter().map(|lang| {lang.get_language_name()}).collect();
  let initial_index: usize =
    option_matches.opt_str("l")
    .and_then(|lang| { language_names.iter().position(|x| { *x == lang }) })
    .unwrap_or(0);

  let mut options = EvalOptions::default();
  options.trace_evaluation = option_matches.opt_present("t");

  let compile = !option_matches.opt_present("i");

  match option_matches.free[..] {
    [] | [_] => {
      let mut repl = Repl::new(languages, initial_index);
      repl.options.show_llvm_ir = option_matches.opt_present("v");
      repl.run();
    }
    [_, ref filename, _..] => {
      let mut language = maaru_lang::Maaru::new();
      run_noninteractive(filename, &mut language, options, compile);
    }
  };
}

fn run_noninteractive<T: ProgrammingLanguageInterface>(filename: &str, language: &mut T, options: EvalOptions, compile: bool) {
  let mut source_file = File::open(&Path::new(filename)).unwrap();
  let mut buffer = String::new();
  source_file.read_to_string(&mut buffer).unwrap();

  if compile {
    if !language.can_compile() {
      panic!("Trying to compile a non-compileable  language");
    } else {
      let llvm_bytecode = language.compile(&buffer);
      compilation_sequence(llvm_bytecode, filename);
    }
  } else {
    let interpretor_output = language.evaluate_in_repl(&buffer, &options);
    interpretor_output.print_to_screen();
  }
}

type LineReader = linefeed::Reader<linefeed::terminal::DefaultTerminal>;
struct Repl {
  options: EvalOptions,
  languages: Vec<Box<ProgrammingLanguageInterface>>,
  current_language_index: usize,
  interpreter_directive_sigil: char,
  reader: LineReader,
}

impl Repl {
  fn new(languages: Vec<Box<ProgrammingLanguageInterface>>, initial_index: usize) -> Repl {
    let mut reader: linefeed::Reader<_> = linefeed::Reader::new("Metainterpreter").unwrap();
    reader.set_prompt(">> ");
    let i = if initial_index < languages.len() { initial_index } else { 0 };
    Repl {
      options: EvalOptions::default(),
      languages: languages,
      current_language_index: i,
      interpreter_directive_sigil: '.',
      reader: reader,
    }
  }
  fn run(&mut self) {
    use linefeed::ReadResult::*;
    println!("MetaInterpreter v 0.05");
    println!("Using language: {}", self.languages[self.current_language_index].get_language_name());
    loop {
      match self.reader.read_line() {
        Err(e) => {
          println!("Terminal read error: {}", e);
        },
        Ok(Eof) => {
          break;
        }
        Ok(Input(ref input)) => {
          self.reader.add_history(input.clone());
          if self.handle_interpreter_directive(input) {
            continue;
          }
          let output = self.input_handler(input);
          println!("=> {}", output);
        }
        _ => (),
      }
    }
    println!("Exiting...");
  }

  fn input_handler(&mut self, input: &str) -> String {
    let ref mut language = self.languages[self.current_language_index];
    let interpretor_output = language.evaluate_in_repl(input, &self.options);
    interpretor_output.to_string()
  }

  fn handle_interpreter_directive(&mut self, input: &str) -> bool {
    match input.chars().nth(0) {
      Some(ch) if ch == self.interpreter_directive_sigil => (),
      _ => return false
    }

    let mut iter = input.chars();
    iter.next();
    let trimmed_sigil: &str = iter.as_str();

    let commands: Vec<&str> = trimmed_sigil
      .split_whitespace()
      .collect();

    let cmd: &str = match commands.get(0).clone() {
      None => return true,
      Some(s) => s
    };

    match cmd {
      "exit" | "quit"  => process::exit(0),
      "history"  => {
        for item in self.reader.history() {
          println!("{}", item);
        }
      },
      "lang" => {
        match commands.get(1) {
          Some(&"show") => {
            for (i, lang) in self.languages.iter().enumerate() {
              if i == self.current_language_index {
                println!("* {}", lang.get_language_name());
              } else {
                println!("{}", lang.get_language_name());
              }
            }
          },
          Some(&"next") => {
            self.current_language_index = (self.current_language_index + 1) % self.languages.len();
            println!("Switching to {}", self.languages[self.current_language_index].get_language_name());
          }
          Some(&"prev") | Some(&"previous") => {
            self.current_language_index = if self.current_language_index == 0 { self.languages.len() - 1 } else { self.current_language_index - 1 };
            println!("Switching to {}", self.languages[self.current_language_index].get_language_name());
          },
          Some(e) => println!("Bad `lang` argument: {}", e),
          None => println!("`lang` - valid arguments `show`, `next`, `prev`|`previous`"),
        }
      },
      "set" => {
        let show = match commands.get(1) {
          Some(&"show") => true,
          Some(&"hide") => false,
          Some(e) => {
            println!("Bad `set` argument: {}", e);
            return true;
          }
          None => {
            println!("`set` - valid arguments `show {{option}}`, `hide {{option}}`");
            return true;
          }
        };
        match commands.get(2) {
          Some(&"tokens") => self.options.debug_tokens = show,
          Some(&"parse") => self.options.debug_parse = show,
          Some(&"eval") => {
            //let ref mut language = self.languages[self.current_language_index];
            //language.set_option("trace_evaluation", show);
          },
          Some(&"llvm") => self.options.show_llvm_ir = show,
          Some(e) => {
            println!("Bad `show`/`hide` argument: {}", e);
            return true;
          }
          None => {
            println!("`show`/`hide` requires an argument");
            return true;
          }
        }
      },
      e => println!("Unknown command: {}", e)
    }
    return true;
  }
}

pub fn compilation_sequence(llvm_code: LLVMCodeString, sourcefile: &str) {
    use std::process::Command;

    let ll_filename = "out.ll";
    let obj_filename = "out.o";
    let q: Vec<&str> = sourcefile.split('.').collect();
    let bin_filename = match &q[..] {
        &[name, "maaru"] => name,
        _ => panic!("Bad filename {}", sourcefile),
    };

    let LLVMCodeString(llvm_str) = llvm_code;

    println!("Compilation process finished for {}", ll_filename);
    File::create(ll_filename)
        .and_then(|mut f| f.write_all(llvm_str.as_bytes()))
        .expect("Error writing file");

    let llc_output = Command::new("llc")
        .args(&["-filetype=obj", ll_filename, "-o", obj_filename])
        .output()
        .expect("Failed to run llc");


    if !llc_output.status.success() {
        println!("{}", String::from_utf8_lossy(&llc_output.stderr));
    }

    let gcc_output = Command::new("gcc")
        .args(&["-o", bin_filename, &obj_filename])
        .output()
        .expect("failed to run gcc");

    if !gcc_output.status.success() {
        println!("{}", String::from_utf8_lossy(&gcc_output.stdout));
        println!("{}", String::from_utf8_lossy(&gcc_output.stderr));
    }

    for filename in [obj_filename].iter() {
        Command::new("rm")
            .arg(filename)
            .output()
            .expect(&format!("failed to run rm {}", filename));
    }
}

fn program_options() -> getopts::Options {
  let mut options = getopts::Options::new();
  options.optflag("i",
                  "interpret",
                  "Interpret source file instead of compiling");
  options.optflag("t",
                  "trace-evaluation",
                  "Print out trace of evaluation");
  options.optflag("v",
                  "llvm-in-repl",
                  "Show LLVM IR in REPL");
  options.optflag("",
                  "list-languages",
                  "Show a list of all supported languages");
  options.optopt("l",
                 "lang",
                 "Start up REPL in a language",
                 "LANGUAGE");
  options.optflag("h",
                  "help",
                  "Show help text");
  options.optflag("m",
                  "virtual-machine",
                  "Start up a virtual machine instead of an interpreter");
  options.optflag("a",
                  "assembler",
                  "Assemble file into bytecode");
  options
}