use std::map;
use std::map::HashMap;
use metadata::cstore;
use driver::session;
use metadata::filesearch;

export get_rpath_flags;

pure fn not_win32(os: session::os) -> bool {
  match os {
      session::os_win32 => false,
      _ => true
  }
}

fn get_rpath_flags(sess: session::session, out_filename: &Path) -> ~[~str] {
    let os = sess.targ_cfg.os;

    // No rpath on windows
    if os == session::os_win32 {
        return ~[];
    }

    debug!("preparing the RPATH!");

    let sysroot = sess.filesearch.sysroot();
    let output = out_filename;
    let libs = cstore::get_used_crate_files(sess.cstore);
    // We don't currently rpath extern libraries, but we know
    // where rustrt is and we know every rust program needs it
    let libs = vec::append_one(libs, get_sysroot_absolute_rt_lib(sess));

    let target_triple = sess.opts.target_triple;
    let rpaths = get_rpaths(os, &sysroot, output, libs, target_triple);
    rpaths_to_flags(rpaths)
}

fn get_sysroot_absolute_rt_lib(sess: session::session) -> Path {
    let r = filesearch::relative_target_lib_path(sess.opts.target_triple);
    sess.filesearch.sysroot().push_rel(&r).push(os::dll_filename("rustrt"))
}

fn rpaths_to_flags(rpaths: &[Path]) -> ~[~str] {
    vec::map(rpaths, |rpath| fmt!("-Wl,-rpath,%s",rpath.to_str()))
}

fn get_rpaths(os: session::os,
              sysroot: &Path,
              output: &Path,
              libs: &[Path],
              target_triple: &str) -> ~[Path] {
    debug!("sysroot: %s", sysroot.to_str());
    debug!("output: %s", output.to_str());
    debug!("libs:");
    for libs.each |libpath| {
        debug!("    %s", libpath.to_str());
    }
    debug!("target_triple: %s", target_triple);

    // Use relative paths to the libraries. Binaries can be moved
    // as long as they maintain the relative relationship to the
    // crates they depend on.
    let rel_rpaths = get_rpaths_relative_to_output(os, output, libs);

    // Make backup absolute paths to the libraries. Binaries can
    // be moved as long as the crates they link against don't move.
    let abs_rpaths = get_absolute_rpaths(libs);

    // And a final backup rpath to the global library location.
    let fallback_rpaths = ~[get_install_prefix_rpath(target_triple)];

    fn log_rpaths(desc: &str, rpaths: &[Path]) {
        debug!("%s rpaths:", desc);
        for rpaths.each |rpath| {
            debug!("    %s", rpath.to_str());
        }
    }

    log_rpaths(~"relative", rel_rpaths);
    log_rpaths(~"absolute", abs_rpaths);
    log_rpaths(~"fallback", fallback_rpaths);

    let mut rpaths = rel_rpaths;
    rpaths.push_all(abs_rpaths);
    rpaths.push_all(fallback_rpaths);

    // Remove duplicates
    let rpaths = minimize_rpaths(rpaths);
    return rpaths;
}

fn get_rpaths_relative_to_output(os: session::os,
                                 output: &Path,
                                 libs: &[Path]) -> ~[Path] {
    vec::map(libs, |a| {
        get_rpath_relative_to_output(os, output, a)
    })
}

fn get_rpath_relative_to_output(os: session::os,
                                output: &Path,
                                lib: &Path) -> Path {
    assert not_win32(os);

    // Mac doesn't appear to support $ORIGIN
    let prefix = match os {
        session::os_linux | session::os_freebsd => "$ORIGIN",
        session::os_macos => "@executable_path",
        session::os_win32 => core::util::unreachable()
    };

    Path(prefix).push_rel(&get_relative_to(&os::make_absolute(output),
                                           &os::make_absolute(lib)))
}

// Find the relative path from one file to another
fn get_relative_to(abs1: &Path, abs2: &Path) -> Path {
    assert abs1.is_absolute;
    assert abs2.is_absolute;
    let abs1 = abs1.normalize();
    let abs2 = abs2.normalize();
    debug!("finding relative path from %s to %s",
           abs1.to_str(), abs2.to_str());
    let split1 = abs1.components;
    let split2 = abs2.components;
    let len1 = vec::len(split1);
    let len2 = vec::len(split2);
    assert len1 > 0;
    assert len2 > 0;

    let max_common_path = uint::min(len1, len2) - 1;
    let mut start_idx = 0;
    while start_idx < max_common_path
        && split1[start_idx] == split2[start_idx] {
        start_idx += 1;
    }

    let mut path = ~[];
    for uint::range(start_idx, len1 - 1) |_i| { path.push(~".."); };

    path.push_all(vec::view(split2, start_idx, len2 - 1));

    if vec::is_not_empty(path) {
        return Path("").push_many(path);
    } else {
        return Path(".");
    }
}

fn get_absolute_rpaths(libs: &[Path]) -> ~[Path] {
    vec::map(libs, |a| get_absolute_rpath(a) )
}

fn get_absolute_rpath(lib: &Path) -> Path {
    os::make_absolute(lib).dir_path()
}

fn get_install_prefix_rpath(target_triple: &str) -> Path {
    let install_prefix = env!("CFG_PREFIX");

    if install_prefix == ~"" {
        fail ~"rustc compiled without CFG_PREFIX environment variable";
    }

    let tlib = filesearch::relative_target_lib_path(target_triple);
    os::make_absolute(&Path(install_prefix).push_rel(&tlib))
}

fn minimize_rpaths(rpaths: &[Path]) -> ~[Path] {
    let set = map::HashMap();
    let mut minimized = ~[];
    for rpaths.each |rpath| {
        let s = rpath.to_str();
        if !set.contains_key(s) {
            minimized.push(*rpath);
            set.insert(s, ());
        }
    }
    return minimized;
}

#[cfg(unix)]
mod test {
    #[legacy_exports];
    #[test]
    fn test_rpaths_to_flags() {
        let flags = rpaths_to_flags(~[Path("path1"),
                                      Path("path2")]);
        assert flags == ~[~"-Wl,-rpath,path1", ~"-Wl,-rpath,path2"];
    }

    #[test]
    fn test_prefix_rpath() {
        let res = get_install_prefix_rpath("triple");
        let d = Path(env!("CFG_PREFIX"))
            .push_rel(&Path("lib/rustc/triple/lib"));
        debug!("test_prefix_path: %s vs. %s",
               res.to_str(),
               d.to_str());
        assert str::ends_with(res.to_str(), d.to_str());
    }

    #[test]
    fn test_prefix_rpath_abs() {
        let res = get_install_prefix_rpath("triple");
        assert res.is_absolute;
    }

    #[test]
    fn test_minimize1() {
        let res = minimize_rpaths([Path("rpath1"),
                                   Path("rpath2"),
                                   Path("rpath1")]);
        assert res == ~[Path("rpath1"), Path("rpath2")];
    }

    #[test]
    fn test_minimize2() {
        let res = minimize_rpaths(~[Path("1a"), Path("2"), Path("2"),
                                    Path("1a"), Path("4a"),Path("1a"),
                                    Path("2"), Path("3"), Path("4a"),
                                    Path("3")]);
        assert res == ~[Path("1a"), Path("2"), Path("4a"), Path("3")];
    }

    #[test]
    fn test_relative_to1() {
        let p1 = Path("/usr/bin/rustc");
        let p2 = Path("/usr/lib/mylib");
        let res = get_relative_to(&p1, &p2);
        assert res == Path("../lib");
    }

    #[test]
    fn test_relative_to2() {
        let p1 = Path("/usr/bin/rustc");
        let p2 = Path("/usr/bin/../lib/mylib");
        let res = get_relative_to(&p1, &p2);
        assert res == Path("../lib");
    }

    #[test]
    fn test_relative_to3() {
        let p1 = Path("/usr/bin/whatever/rustc");
        let p2 = Path("/usr/lib/whatever/mylib");
        let res = get_relative_to(&p1, &p2);
        assert res == Path("../../lib/whatever");
    }

    #[test]
    fn test_relative_to4() {
        let p1 = Path("/usr/bin/whatever/../rustc");
        let p2 = Path("/usr/lib/whatever/mylib");
        let res = get_relative_to(&p1, &p2);
        assert res == Path("../lib/whatever");
    }

    #[test]
    fn test_relative_to5() {
        let p1 = Path("/usr/bin/whatever/../rustc");
        let p2 = Path("/usr/lib/whatever/../mylib");
        let res = get_relative_to(&p1, &p2);
        assert res == Path("../lib");
    }

    #[test]
    fn test_relative_to6() {
        let p1 = Path("/1");
        let p2 = Path("/2/3");
        let res = get_relative_to(&p1, &p2);
        assert res == Path("2");
    }

    #[test]
    fn test_relative_to7() {
        let p1 = Path("/1/2");
        let p2 = Path("/3");
        let res = get_relative_to(&p1, &p2);
        assert res == Path("..");
    }

    #[test]
    fn test_relative_to8() {
        let p1 = Path("/home/brian/Dev/rust/build/").push_rel(
            &Path("stage2/lib/rustc/i686-unknown-linux-gnu/lib/librustc.so"));
        let p2 = Path("/home/brian/Dev/rust/build/stage2/bin/..").push_rel(
            &Path("lib/rustc/i686-unknown-linux-gnu/lib/libstd.so"));
        let res = get_relative_to(&p1, &p2);
        debug!("test_relative_tu8: %s vs. %s",
               res.to_str(),
               Path(".").to_str());
        assert res == Path(".");
    }

    #[test]
    #[cfg(target_os = "linux")]
    fn test_rpath_relative() {
      let o = session::os_linux;
      let res = get_rpath_relative_to_output(o,
            &Path("bin/rustc"), &Path("lib/libstd.so"));
      assert res.to_str() == ~"$ORIGIN/../lib";
    }

    #[test]
    #[cfg(target_os = "freebsd")]
    fn test_rpath_relative() {
        let o = session::os_freebsd;
        let res = get_rpath_relative_to_output(o,
            &Path("bin/rustc"), &Path("lib/libstd.so"));
        assert res.to_str() == ~"$ORIGIN/../lib";
    }

    #[test]
    #[cfg(target_os = "macos")]
    fn test_rpath_relative() {
        // this is why refinements would be nice
        let o = session::os_macos;
        let res = get_rpath_relative_to_output(o,
                                               &Path("bin/rustc"),
                                               &Path("lib/libstd.so"));
        assert res.to_str() == ~"@executable_path/../lib";
    }

    #[test]
    fn test_get_absolute_rpath() {
        let res = get_absolute_rpath(&Path("lib/libstd.so"));
        debug!("test_get_absolute_rpath: %s vs. %s",
               res.to_str(),
               os::make_absolute(&Path("lib")).to_str());

        assert res == os::make_absolute(&Path("lib"));
    }
}
