// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// rusti - REPL using the JIT backend

#[link(name = "rusti",
       vers = "0.7-pre",
       uuid = "7fb5bf52-7d45-4fee-8325-5ad3311149fc",
       url = "https://github.com/mozilla/rust/tree/master/src/rusti")];

#[license = "MIT/ASL2"];
#[crate_type = "lib"];

#[allow(vecs_implicitly_copyable,
        non_implicitly_copyable_typarams)];

extern mod std(vers = "0.7-pre");
extern mod rustc(vers = "0.7-pre");
extern mod syntax(vers = "0.7-pre");

use core::*;
use rustc::driver::{driver, session};
use syntax::{ast, diagnostic};
use syntax::ast_util::*;
use syntax::parse::token;
use syntax::print::{pp, pprust};
use std::rl;

/**
 * A structure shared across REPL instances for storing history
 * such as statements and view items. I wish the AST was sendable.
 */
struct Repl {
    prompt: ~str,
    binary: ~str,
    running: bool,
    view_items: ~str,
    lib_search_paths: ~[~str],
    stmts: ~str
}

// Action to do after reading a :command
enum CmdAction {
    action_none,
    action_run_line(~str),
}

/// A utility function that hands off a pretty printer to a callback.
fn with_pp(intr: @token::ident_interner,
           cb: &fn(@pprust::ps, @io::Writer)) -> ~str {
    do io::with_str_writer |writer| {
        let pp = pprust::rust_printer(writer, intr);

        cb(pp, writer);
        pp::eof(pp.s);
    }
}

/**
 * The AST (or the rest of rustc) are not sendable yet,
 * so recorded things are printed to strings. A terrible hack that
 * needs changes to rustc in order to be outed. This is unfortunately
 * going to cause the REPL to regress in parser performance,
 * because it has to parse the statements and view_items on each
 * input.
 */
fn record(repl: Repl, blk: @ast::blk, intr: @token::ident_interner) -> Repl {
    let view_items = if blk.node.view_items.len() > 0 {
        let new_view_items = do with_pp(intr) |pp, writer| {
            for blk.node.view_items.each |view_item| {
                pprust::print_view_item(pp, *view_item);
                writer.write_line(~"");
            }
        };

        debug!("new view items %s", new_view_items);

        repl.view_items + "\n" + new_view_items
    } else { repl.view_items };
    let stmts = if blk.node.stmts.len() > 0 {
        let new_stmts = do with_pp(intr) |pp, writer| {
            for blk.node.stmts.each |stmt| {
                match stmt.node {
                    ast::stmt_decl(*) | ast::stmt_mac(*) => {
                        pprust::print_stmt(pp, *stmt);
                        writer.write_line(~"");
                    }
                    ast::stmt_expr(expr, _) | ast::stmt_semi(expr, _) => {
                        match expr.node {
                            ast::expr_assign(*) |
                            ast::expr_assign_op(*) |
                            ast::expr_swap(*) => {
                                pprust::print_stmt(pp, *stmt);
                                writer.write_line(~"");
                            }
                            _ => {}
                        }
                    }
                }
            }
        };

        debug!("new stmts %s", new_stmts);

        repl.stmts + "\n" + new_stmts
    } else { repl.stmts };

    Repl{
        view_items: view_items,
        stmts: stmts,
        .. repl
    }
}

/// Run an input string in a Repl, returning the new Repl.
fn run(repl: Repl, input: ~str) -> Repl {
    let options = @session::options {
        crate_type: session::unknown_crate,
        binary: @repl.binary,
        addl_lib_search_paths: repl.lib_search_paths.map(|p| Path(*p)),
        jit: true,
        .. *session::basic_options()
    };

    debug!("building driver input");
    let head = include_str!("wrapper.rs").to_owned();
    let foot = fmt!("%s\nfn main() {\n%s\n\nprint({\n%s\n})\n}",
                    repl.view_items, repl.stmts, input);
    let wrapped = driver::str_input(head + foot);

    debug!("inputting %s", head + foot);

    debug!("building a driver session");
    let sess = driver::build_session(options, diagnostic::emit);

    debug!("building driver configuration");
    let cfg = driver::build_configuration(sess,
                                          @repl.binary,
                                          &wrapped);

    let outputs = driver::build_output_filenames(&wrapped, &None, &None, sess);
    debug!("calling compile_upto");
    let (crate, _) = driver::compile_upto(sess, cfg, &wrapped,
                                          driver::cu_everything,
                                          Some(outputs));

    let mut opt = None;

    for crate.node.module.items.each |item| {
        match item.node {
            ast::item_fn(_, _, _, _, blk) => {
                if item.ident == sess.ident_of("main") {
                    opt = blk.node.expr;
                }
            }
            _ => {}
        }
    }

    let blk = match opt.get().node {
        ast::expr_call(_, exprs, _) => {
            match exprs[0].node {
                ast::expr_block(blk) => @blk,
                _ => fail!()
            }
        }
        _ => fail!()
    };
    debug!("recording input into repl history");
    record(repl, blk, sess.parse_sess.interner)
}

// Compiles a crate given by the filename as a library if the compiled
// version doesn't exist or is older than the source file. Binary is
// the name of the compiling executable. Returns Some(true) if it
// successfully compiled, Some(false) if the crate wasn't compiled
// because it already exists and is newer than the source file, or
// None if there were compile errors.
fn compile_crate(src_filename: ~str, binary: ~str) -> Option<bool> {
    match do task::try {
        let src_path = Path(src_filename);
        let options = @session::options {
            binary: @binary,
            addl_lib_search_paths: ~[os::getcwd()],
            .. *session::basic_options()
        };
        let input = driver::file_input(src_path);
        let sess = driver::build_session(options, diagnostic::emit);
        *sess.building_library = true;
        let cfg = driver::build_configuration(sess, @binary, &input);
        let outputs = driver::build_output_filenames(
            &input, &None, &None, sess);
        // If the library already exists and is newer than the source
        // file, skip compilation and return None.
        let mut should_compile = true;
        let dir = os::list_dir_path(&Path(outputs.out_filename.dirname()));
        let maybe_lib_path = do dir.find |file| {
            // The actual file's name has a hash value and version
            // number in it which is unknown at this time, so looking
            // for a file that matches out_filename won't work,
            // instead we guess which file is the library by matching
            // the prefix and suffix of out_filename to files in the
            // directory.
            let file_str = file.filename().get();
            file_str.starts_with(outputs.out_filename.filestem().get())
                && file_str.ends_with(outputs.out_filename.filetype().get())
        };
        match maybe_lib_path {
            Some(lib_path) => {
                let (src_mtime, _) = src_path.get_mtime().get();
                let (lib_mtime, _) = lib_path.get_mtime().get();
                if lib_mtime >= src_mtime {
                    should_compile = false;
                }
            },
            None => { },
        }
        if (should_compile) {
            io::println(fmt!("compiling %s...", src_filename));
            driver::compile_upto(sess, cfg, &input, driver::cu_everything,
                                 Some(outputs));
            true
        } else { false }
    } {
        Ok(true) => Some(true),
        Ok(false) => Some(false),
        Err(_) => None,
    }
}

/// Tries to get a line from rl after outputting a prompt. Returns
/// None if no input was read (e.g. EOF was reached).
fn get_line(use_rl: bool, prompt: ~str) -> Option<~str> {
    if use_rl {
        let result = unsafe { rl::read(prompt) };

        match result {
            None => None,
            Some(line) => {
                unsafe { rl::add_history(line) };
                Some(line)
            }
        }
    } else {
        if io::stdin().eof() {
            None
        } else {
            Some(io::stdin().read_line())
        }
    }
}

/// Run a command, e.g. :clear, :exit, etc.
fn run_cmd(repl: &mut Repl, _in: @io::Reader, _out: @io::Writer,
           cmd: ~str, args: ~[~str], use_rl: bool) -> CmdAction {
    let mut action = action_none;
    match cmd {
        ~"exit" => repl.running = false,
        ~"clear" => {
            repl.view_items = ~"";
            repl.stmts = ~"";

            // XXX: Win32 version of linenoise can't do this
            //rl::clear();
        }
        ~"help" => {
            io::println(
                ~":{\\n ..lines.. \\n:}\\n - execute multiline command\n" +
                ~":load <crate> ... - \
                  loads given crates as dynamic libraries\n" +
                ~":clear - clear the bindings\n" +
                ~":exit - exit from the repl\n" +
                ~":help - show this message");
        }
        ~"load" => {
            let mut loaded_crates: ~[~str] = ~[];
            for args.each |arg| {
                let (crate, filename) =
                    if arg.ends_with(".rs") || arg.ends_with(".rc") {
                    (arg.substr(0, arg.len() - 3).to_owned(), *arg)
                } else {
                    (*arg, arg + ~".rs")
                };
                match compile_crate(filename, repl.binary) {
                    Some(_) => loaded_crates.push(crate),
                    None => { }
                }
            }
            for loaded_crates.each |crate| {
                let crate_path = Path(*crate);
                let crate_dir = crate_path.dirname();
                let crate_name = crate_path.filename().get();
                if !repl.view_items.contains(*crate) {
                    repl.view_items += fmt!("extern mod %s;\n", crate_name);
                    if !repl.lib_search_paths.contains(&crate_dir) {
                        repl.lib_search_paths.push(crate_dir);
                    }
                }
            }
            if loaded_crates.is_empty() {
                io::println("no crates loaded");
            } else {
                io::println(fmt!("crates loaded: %s",
                                 str::connect(loaded_crates, ", ")));
            }
        }
        ~"{" => {
            let mut multiline_cmd = ~"";
            let mut end_multiline = false;
            while (!end_multiline) {
                match get_line(use_rl, ~"rusti| ") {
                    None => fail!(~"unterminated multiline command :{ .. :}"),
                    Some(line) => {
                        if str::trim(line) == ~":}" {
                            end_multiline = true;
                        } else {
                            multiline_cmd += line + ~"\n";
                        }
                    }
                }
            }
            action = action_run_line(multiline_cmd);
        }
        _ => io::println(~"unknown cmd: " + cmd)
    }
    return action;
}

/// Executes a line of input, which may either be rust code or a
/// :command. Returns a new Repl if it has changed.
fn run_line(repl: &mut Repl, in: @io::Reader, out: @io::Writer, line: ~str,
            use_rl: bool)
    -> Option<Repl> {
    if line.starts_with(~":") {
        let full = line.substr(1, line.len() - 1);
        let mut split = ~[];
        for str::each_word(full) |word| { split.push(word.to_owned()) }
        let len = split.len();

        if len > 0 {
            let cmd = split[0];

            if !cmd.is_empty() {
                let args = if len > 1 {
                    vec::slice(split, 1, len).to_vec()
                } else { ~[] };

                match run_cmd(repl, in, out, cmd, args, use_rl) {
                    action_none => { }
                    action_run_line(multiline_cmd) => {
                        if !multiline_cmd.is_empty() {
                            return run_line(repl, in, out, multiline_cmd, use_rl);
                        }
                    }
                }
                return None;
            }
        }
    }

    let r = *repl;
    let result = do task::try {
        run(r, line)
    };

    if result.is_ok() {
        return Some(result.get());
    }
    return None;
}

pub fn main() {
    let args = os::args();
    let in = io::stdin();
    let out = io::stdout();
    let mut repl = Repl {
        prompt: ~"rusti> ",
        binary: args[0],
        running: true,
        view_items: ~"",
        lib_search_paths: ~[],
        stmts: ~""
    };

    let istty = unsafe { libc::isatty(libc::STDIN_FILENO as i32) } != 0;

    // only print this stuff if the user is actually typing into rusti
    if istty {
        io::println("WARNING: The Rust REPL is experimental and may be");
        io::println("unstable. If you encounter problems, please use the");
        io::println("compiler instead.");

        unsafe {
            do rl::complete |line, suggest| {
                if line.starts_with(":") {
                    suggest(~":clear");
                    suggest(~":exit");
                    suggest(~":help");
                    suggest(~":load");
                }
            }
        }
    }

    while repl.running {
        match get_line(istty, repl.prompt) {
            None => break,
            Some(line) => {
                if line.is_empty() {
                    if istty {
                        io::println(~"()");
                    }
                    loop;
                }
                match run_line(&mut repl, in, out, line, istty) {
                    Some(new_repl) => repl = new_repl,
                    None => { }
                }
            }
        }
    }
}