use std::{
    collections::{HashMap, HashSet},
    env,
    ffi::OsString,
    path::PathBuf,
    process::Command,
};

#[cfg(target_os = "windows")]
use std::path::Path;

#[cfg(not(target_os = "macos"))]
use std::fs;

macro_rules! ci_stderr_log {
    () => (eprint!("\n"));
    ($($arg:tt)*) => ({
        if env::var_os("CI_STDERR_LOG").is_some() { eprintln!($($arg)*) }
    })
}

fn rbconfig(key: &str) -> String {
    let ruby = env::var_os("RUBY").unwrap_or(OsString::from("ruby"));

    let config = Command::new(ruby)
        .arg("-e")
        .arg(format!("print RbConfig::CONFIG['{}']", key))
        .output()
        .unwrap_or_else(|e| panic!("ruby not found: {}", e));

    String::from_utf8(config.stdout).expect("RbConfig value not UTF-8!")
}

#[cfg(not(target_os = "macos"))]
fn macos_static_ruby_dep() {}

#[cfg(target_os = "macos")]
fn macos_static_ruby_dep() {
    println!("cargo:rustc-link-lib=framework=Foundation");
}

#[cfg(not(target_os = "windows"))]
fn windows_static_ruby_dep() {}

// Windows needs ligmp-10.dll as gmp.lib
#[cfg(target_os = "windows")]
fn windows_static_ruby_dep() {
    Command::new("build/windows/vcbuild.cmd")
        .arg("-arch=x64")
        .arg("-host_arch=x64")
        .arg("&&")
        .arg("dumpbin")
        .arg("/exports")
        .arg("/out:exports.txt")
        .arg(format!(
            "{}/ruby_builtin_dlls/libgmp-10.dll",
            rbconfig("bindir")
        ))
        .output()
        .unwrap();

    Command::new("build/windows/exports.bat").output().unwrap();

    let deps_dir = Path::new("target")
        .join(env::var_os("PROFILE").unwrap())
        .join("deps");

    Command::new("build/windows/vcbuild.cmd")
        .arg("-arch=x64")
        .arg("-host_arch=x64")
        .arg("&&")
        .arg("lib")
        .arg("/def:exports.def")
        .arg("/name:gmp")
        .arg(format!("/libpath:{}/ruby_builtin_dlls", rbconfig("bindir")))
        .arg("/machine:x64")
        .arg(format!("/out:{}/gmp.lib", deps_dir.to_string_lossy()))
        .output()
        .unwrap();

    fs::remove_file("exports.def").expect("couldn't remove exports.def");
    fs::remove_file("exports.txt").expect("couldn't remove exports.txt");
}

fn use_static() {
    if let Some(location) = env::var_os("RUBY_STATIC_PATH").map(|s| s.to_string_lossy().to_string())
    {
        println!("cargo:rustc-link-search={}", location);
    }

    // If Windows
    windows_static_ruby_dep();

    // If Mac OS
    macos_static_ruby_dep();

    // **Flags must be last in order for linking!**
    static_linker_args();

    ci_stderr_log!("Using static linker flags");
}

fn use_dylib() {
    println!("cargo:rustc-link-search={}", rbconfig("libdir"));
    dynamic_linker_args();
    ci_stderr_log!("Using dynamic linker flags");
}

#[cfg(target_os = "windows")]
fn delete<'a>(s: &'a str, from: &'a str) -> String {
    let mut result = String::new();
    let mut last_end = 0;
    for (start, part) in s.match_indices(from) {
        result.push_str(unsafe { s.get_unchecked(last_end..start) });
        last_end = start + part.len();
    }
    result.push_str(unsafe { s.get_unchecked(last_end..s.len()) });
    result
}

#[cfg(target_os = "windows")]
fn purge_refptr_text() {
    let buffer = fs::read_to_string("exports.def").expect("Failed to read 'exports.def'");
    fs::write("exports.def", delete(&buffer, ".refptr."))
        .expect("Failed to write update to 'exports.def'");
}

#[cfg(target_os = "windows")]
fn windows_support() {
    println!("cargo:rustc-link-search={}", rbconfig("bindir"));
    let mingw_libs: OsString = env::var_os("MINGW_LIBS").unwrap_or(OsString::from(format!(
        "{}/ruby_builtin_dlls",
        rbconfig("bindir")
    )));
    println!("cargo:rustc-link-search={}", mingw_libs.to_string_lossy());

    let deps_dir = Path::new("target")
        .join(env::var_os("PROFILE").unwrap())
        .join("deps");
    let libruby_so = rbconfig("LIBRUBY_SO");
    let ruby_dll = Path::new(&libruby_so);
    let name = ruby_dll.file_stem().unwrap();
    let target = deps_dir.join(format!("{}.lib", name.to_string_lossy()));

    Command::new("build/windows/vcbuild.cmd")
        .arg("-arch=x64")
        .arg("-host_arch=x64")
        .arg("&&")
        .arg("dumpbin")
        .arg("/exports")
        .arg("/out:exports.txt")
        .arg(Path::new(&rbconfig("bindir")).join(&libruby_so))
        .output()
        .unwrap();

    Command::new("build/windows/exports.bat").output().unwrap();

    purge_refptr_text();
    Command::new("build/windows/vcbuild.cmd")
        .arg("-arch=x64")
        .arg("-host_arch=x64")
        .arg("&&")
        .arg("lib")
        .arg("/def:exports.def")
        .arg(format!("/name:{}", name.to_string_lossy()))
        .arg(format!("/libpath:{}", rbconfig("bindir")))
        .arg("/machine:x64")
        .arg(format!("/out:{}", target.to_string_lossy()))
        .output()
        .unwrap();

    fs::remove_file("exports.def").expect("couldn't remove exports.def");
    fs::remove_file("exports.txt").expect("couldn't remove exports.txt");
}

#[cfg(not(target_os = "windows"))]
fn windows_support() {}

#[cfg(any(
    target_os = "linux",
    target_os = "android",
    target_os = "freebsd",
    target_os = "openbsd"
))]
use std::os::unix::fs::symlink;

#[cfg(any(
    target_os = "linux",
    target_os = "android",
    target_os = "freebsd",
    target_os = "openbsd"
))]
fn ruby_lib_link_name() -> String {
    // Rust with linker search paths doesn't seem to use those paths
    // but rather resorts to the systems Ruby.  So we symlink into
    // our own deps directory for it to work.
    let so_file = format!("libruby.so.{}.{}", rbconfig("MAJOR"), rbconfig("MINOR"));
    let out_dir = env::var("OUT_DIR").unwrap();
    let working_dir = out_dir.splitn(2, "/target").next().unwrap();
    let destination = format!(
        "{}/target/{}/deps",
        working_dir,
        env::var("PROFILE").unwrap()
    );
    let _ = fs::create_dir_all(&destination).expect("create_dir_all fail");
    let source = format!("{}/{}", rbconfig("libdir"), so_file);
    let target = format!("{}/{}", destination, so_file);

    if fs::read_link(&target).is_err() {
        let _ = symlink(source, target).expect("symlink fail");
    }

    rbconfig("RUBY_SO_NAME")
}

#[cfg(target_os = "macos")]
fn ruby_lib_link_name() -> String {
    format!(
        "{}.{}.{}",
        rbconfig("RUBY_BASE_NAME"),
        rbconfig("MAJOR"),
        rbconfig("MINOR")
    )
}

#[cfg(target_os = "windows")]
fn ruby_lib_link_name() -> String {
    rbconfig("RUBY_SO_NAME")
}

fn dynamic_linker_args() {
    let mut library = Library::new();
    library.parse_libs_cflags(rbconfig("LIBRUBYARG_SHARED").as_bytes(), false);
    println!("cargo:rustc-link-lib=dylib={}", ruby_lib_link_name());
    library.parse_libs_cflags(rbconfig("LIBS").as_bytes(), false);
}

fn static_linker_args() {
    let mut library = Library::new();
    library.parse_libs_cflags(rbconfig("LIBRUBYARG_SHARED").as_bytes(), true);
    library.parse_libs_cflags(
        format!("-l{}-static", rbconfig("RUBY_SO_NAME")).as_bytes(),
        true,
    );
    library.parse_libs_cflags(rbconfig("MAINLIBS").as_bytes(), false);
}

#[derive(Debug)]
pub struct Library {
    pub libs: Vec<String>,
    pub link_paths: Vec<PathBuf>,
    pub frameworks: Vec<String>,
    pub framework_paths: Vec<PathBuf>,
    pub include_paths: Vec<PathBuf>,
    pub defines: HashMap<String, Option<String>>,
    pub version: String,
    _priv: (),
}

impl Library {
    fn new() -> Library {
        Library {
            libs: Vec::new(),
            link_paths: Vec::new(),
            include_paths: Vec::new(),
            frameworks: Vec::new(),
            framework_paths: Vec::new(),
            defines: HashMap::new(),
            version: String::new(),
            _priv: (),
        }
    }

    fn parse_libs_cflags(&mut self, output: &[u8], statik: bool) {
        let mut is_msvc = false;
        if let Ok(target) = env::var("TARGET") {
            if target.contains("msvc") {
                is_msvc = true;
            }
        }

        let words = split_flags(output);
        let parts = words
            .iter()
            .filter(|l| l.len() > 2)
            .map(|arg| (&arg[0..2], &arg[2..]))
            .collect::<HashSet<_>>();

        let mut dirs = Vec::new();
        for &(flag, val) in &parts {
            match flag {
                "-L" => {
                    let meta = format!("rustc-link-search=native={}", val);
                    println!("cargo:{}", &meta);
                    dirs.push(PathBuf::from(val));
                    self.link_paths.push(PathBuf::from(val));
                }
                "-F" => {
                    let meta = format!("rustc-link-search=framework={}", val);
                    println!("cargo:{}", &meta);
                    self.framework_paths.push(PathBuf::from(val));
                }
                "-I" => {
                    self.include_paths.push(PathBuf::from(val));
                }
                "-l" => {
                    // These are provided by the CRT with MSVC
                    if is_msvc && ["m", "c", "pthread"].contains(&val) {
                        continue;
                    }

                    if is_static() && statik {
                        let meta = format!("rustc-link-lib=static={}", val);
                        println!("cargo:{}", &meta);
                    } else {
                        let meta = format!("rustc-link-lib={}", val);
                        println!("cargo:{}", &meta);
                    }

                    self.libs.push(val.to_string());
                }
                "-D" => {
                    let mut iter = val.split("=");
                    self.defines.insert(
                        iter.next().unwrap().to_owned(),
                        iter.next().map(|s| s.to_owned()),
                    );
                }
                _ => {}
            }
        }

        let mut iter = words.iter().flat_map(|arg| {
            if arg.starts_with("-Wl,") {
                arg[4..].split(',').collect()
            } else {
                vec![arg.as_ref()]
            }
        });
        while let Some(part) = iter.next() {
            if part != "-framework" {
                continue;
            }
            if let Some(lib) = iter.next() {
                let meta = format!("rustc-link-lib=framework={}", lib);
                println!("cargo:{}", &meta);
                self.frameworks.push(lib.to_string());
            }
        }
    }
}

fn split_flags(output: &[u8]) -> Vec<String> {
    let mut word = Vec::new();
    let mut words = Vec::new();

    for &b in output {
        match b {
            b' ' => {
                if !word.is_empty() {
                    words.push(String::from_utf8(word).unwrap());
                    word = Vec::new();
                }
            }
            _ => word.push(b),
        }
    }

    if !word.is_empty() {
        words.push(String::from_utf8(word).unwrap());
    }

    words
}

fn is_static() -> bool {
    env::var_os("RUBY_STATIC").is_some()
}

fn should_link() -> bool {
    std::env::var_os("NO_LINK_RUTIE").is_none()
        && std::env::var_os("CARGO_FEATURE_NO_LINK").is_none()
}

fn main() {
    // Ruby programs calling Rust doesn't need cc linking
    if should_link() {
        // If windows OS do windows stuff
        windows_support();

        if is_static() {
            ci_stderr_log!("RUBY_STATIC is set");
            use_static()
        } else {
            match rbconfig("ENABLE_SHARED").as_str() {
                "no" => use_static(),
                "yes" => use_dylib(),
                _ => {
                    let msg = "Error! Couldn't find a valid value for \
                    RbConfig::CONFIG['ENABLE_SHARED']. \
                    This may mean that your ruby's build config is corrupted. \
                    Possible solution: build a new Ruby with the `--enable-shared` configure opt.";
                    ci_stderr_log!("{}", &msg);
                    panic!("{}", msg)
                }
            }
        }
    }
}