import std::map;
import std::map::hashmap;
import metadata::cstore;
import driver::session;
import 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: ~str) -> ~[~str] {
    let os = sess.targ_cfg.os;

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

    debug!{"preparing the RPATH!"};

    let cwd = os::getcwd();
    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, cwd, sysroot, output, libs, target_triple);
    rpaths_to_flags(rpaths)
}

fn get_sysroot_absolute_rt_lib(sess: session::session) -> path::Path {
    let mut path = vec::append(~[sess.filesearch.sysroot()],
                           filesearch::relative_target_lib_path(
                               sess.opts.target_triple));
    vec::push(path, os::dll_filename(~"rustrt"));
    path::connect_many(path)
}

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

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

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

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

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

    let mut rpaths = rel_rpaths;
    vec::push_all(rpaths, abs_rpaths);
    vec::push_all(rpaths, fallback_rpaths);

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

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

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

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

    prefix + get_relative_to(
        get_absolute(cwd, output),
        get_absolute(cwd, lib))
}

// Find the relative path from one file to another
fn get_relative_to(abs1: path::Path, abs2: path::Path) -> path::Path {
    assert path::path_is_absolute(abs1);
    assert path::path_is_absolute(abs2);
    debug!{"finding relative path from %s to %s",
           abs1, abs2};
    let normal1 = path::normalize(abs1);
    let normal2 = path::normalize(abs2);
    let split1 = path::split(normal1);
    let split2 = path::split(normal2);
    let len1 = vec::len(split1);
    let len2 = vec::len(split2);
    assert len1 > 0u;
    assert len2 > 0u;

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

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

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

    if vec::is_not_empty(path) {
        return path::connect_many(path);
    } else {
        return ~".";
    }
}

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

fn get_absolute_rpath(cwd: path::Path, &&lib: path::Path) -> ~str {
    path::dirname(get_absolute(cwd, lib))
}

fn get_absolute(cwd: path::Path, lib: path::Path) -> path::Path {
    if path::path_is_absolute(lib) {
        lib
    } else {
        path::connect(cwd, lib)
    }
}

fn get_install_prefix_rpath(cwd: path::Path, target_triple: ~str) -> ~str {
    let install_prefix = env!{"CFG_PREFIX"};

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

    let path = vec::append(
        ~[install_prefix],
        filesearch::relative_target_lib_path(target_triple));
    get_absolute(cwd, path::connect_many(path))
}

fn minimize_rpaths(rpaths: ~[~str]) -> ~[~str] {
    let set = map::str_hash::<()>();
    let mut minimized = ~[];
    for rpaths.each |rpath| {
        if !set.contains_key(rpath) {
            vec::push(minimized, rpath);
            set.insert(rpath, ());
        }
    }
    return minimized;
}

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

    #[test]
    fn test_get_absolute1() {
        let cwd = ~"/dir";
        let lib = ~"some/path/lib";
        let res = get_absolute(cwd, lib);
        assert res == ~"/dir/some/path/lib";
    }

    #[test]
    fn test_get_absolute2() {
        let cwd = ~"/dir";
        let lib = ~"/some/path/lib";
        let res = get_absolute(cwd, lib);
        assert res == ~"/some/path/lib";
    }

    #[test]
    fn test_prefix_rpath() {
        let res = get_install_prefix_rpath(~"/usr/lib", ~"triple");
        let d = path::connect(env!{"CFG_PREFIX"}, ~"/lib/rustc/triple/lib");
        assert str::ends_with(res, d);
    }

    #[test]
    fn test_prefix_rpath_abs() {
        let res = get_install_prefix_rpath(~"/usr/lib", ~"triple");
        assert path::path_is_absolute(res);
    }

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

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

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

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

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

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

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

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

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

    #[test]
    fn test_relative_to8() {
        let p1 = ~"/home/brian/Dev/rust/build/"
            + ~"stage2/lib/rustc/i686-unknown-linux-gnu/lib/librustc.so";
        let p2 = ~"/home/brian/Dev/rust/build/stage2/bin/.."
            + ~"/lib/rustc/i686-unknown-linux-gnu/lib/libstd.so";
        let res = get_relative_to(p1, p2);
        assert res == ~".";
    }

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

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

    #[test]
    fn test_get_absolute_rpath() {
        let res = get_absolute_rpath(~"/usr", ~"lib/libstd.so");
        assert res == ~"/usr/lib";
    }
}