use anyhow::{anyhow, Result};
use std::env;
use std::path::Path;

use minutus_mruby_build_utils::MRubyManager;

fn check_command(cmd: &[&str]) {
    if std::process::Command::new(cmd[0])
        .args(&cmd[1..])
        .output()
        .is_err()
    {
        println!("cargo:warning={} command does not exist", cmd[1]);
        panic!("{} command does not exist", cmd[1]);
    }
}

fn extract_mruby_source_code() -> Result<()> {
    let workdir = env::var("OUT_DIR")?;
    let workdir = Path::new(&workdir);

    let archive_path = env::current_dir()?
        .join("mrubies")
        .join(format!("{}.tar.gz", mruby_version()));
    if !archive_path.exists() {
        println!("cargo:warning={} does not exist", archive_path.display());
        return Err(anyhow!("{} does not exist", archive_path.display()));
    }

    if workdir.join("mruby").exists() {
        return Ok(());
    }

    let tar_gz = std::fs::read(archive_path)?;
    let tar = {
        use bytes::Buf;
        flate2::read::GzDecoder::new(tar_gz.reader())
    };
    let mut archive = tar::Archive::new(tar);
    archive.unpack(&workdir).unwrap();

    std::fs::rename(
        workdir.join(format!("mruby-{}", mruby_version())),
        workdir.join("mruby"),
    )?;

    Ok(())
}

fn build_on_doc_rs() -> Result<()> {
    extract_mruby_source_code()?;
    MRubyManager::new()
        .mruby_version(&mruby_version())
        .link(true)
        .download(false)
        .run();
    compile_bridge()?;

    println!("Finish build.rs");

    Ok(())
}

fn main() -> Result<()> {
    // docs.rs does not allow network access. So we need different settings.
    if std::env::var("DOCS_RS").is_ok() {
        build_on_doc_rs()?;
        return Ok(());
    }

    check_command(&["ruby", "-v"]);
    println!("cargo:rerun-if-changed=src/bridge");
    println!("cargo:rerun-if-changed=build.rs");

    let out_dir = env::var("OUT_DIR")?;
    let build_config_copy = Path::new(&out_dir).join("build_config.rb");
    std::fs::copy(
        &env::current_dir()?.join("build_config.rb"),
        &build_config_copy,
    )?;

    let do_link = env::var("CARGO_FEATURE_LINK_MRUBY").is_ok();
    MRubyManager::new()
        .mruby_version(&mruby_version())
        .link(do_link)
        .build_config(&build_config_copy)
        .run();
    compile_bridge()?;

    println!("Finish build.rs");

    Ok(())
}

fn mruby_version() -> String {
    let default = "3.2.0";
    let supported_versions = &["3.1.0", "3.2.0", "MASTER"];
    for version in supported_versions.into_iter() {
        if env::var(format!(
            "CARGO_FEATURE_MRUBY_{}",
            str::replace(version, ".", "_")
        ))
        .is_ok()
        {
            return version.to_lowercase().to_string();
        }
    }
    return default.to_string();
}

fn compile_bridge() -> Result<()> {
    let out_dir = std::env::var("OUT_DIR")?;
    let out_dir = Path::new(&out_dir);
    // generate bridge.c
    let output = std::process::Command::new("ruby")
        .args(&["all.rb"])
        .current_dir(Path::new("src").join("bridge"))
        .output();
    let output = match output {
        Ok(o) => o,
        Err(e) => {
            println!("cargo:warning={}", e);
            panic!("{}", e);
        }
    };
    if !output.status.success() {
        eprintln!("{}", String::from_utf8(output.stderr)?);
        return Err(anyhow!("Failed to execute command"));
    }
    std::fs::write(out_dir.join("bridge.c"), output.stdout)?;

    // generate binding
    println!("Start generating binding");

    let mruby_include_path = Path::new(out_dir).join("mruby").join("include");
    println!("include path: {}", mruby_include_path.to_str().unwrap());

    let out_path = Path::new(out_dir).join("mruby.rs");
    let allowlist_types = &[
        "minu_.*",
        "RClass",
        "RObject",
        "RBasic",
        "RData",
        "RString",
        "RInteger",
        "RFloat",
        "RRational",
        "RComplex",
        "RArray",
        "RHash",
        "RRange",
        "RProc",
        "RException",
    ];
    let allowlist_functions = &["minu_.*", "mrb_raise", "mrb_get_args"];
    let bindings = bindgen::Builder::default()
        .clang_arg(format!("-I{}", mruby_include_path.to_str().unwrap()))
        .header(out_dir.join("bridge.c").to_string_lossy())
        .allowlist_type(allowlist_types.join("|"))
        .allowlist_function(allowlist_functions.join("|"))
        .layout_tests(false)
        .generate_comments(false)
        .parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))
        .generate()?;
    bindings.write_to_file(out_path)?;

    println!("Finish generating binding");

    // Compile
    println!("Start compiling binding");

    cc::Build::new()
        .file(out_dir.join("bridge.c"))
        .include(mruby_include_path)
        .compile("minutus_bridge");

    println!("Finish compiling binding");

    Ok(())
}