use std::env;
use std::env::set_current_dir;
use std::path::{Path, PathBuf};
use std::process::Command;

extern crate cc;

fn submodules_init(project_dir: &Path) {
    let mark_file_path = ".submodules-initialized";

    // Check if the mark file exists
    if !Path::new(mark_file_path).exists() {
        // If mark file doesn't exist, initialize submodule
        if Command::new("git")
            .args(["submodule", "init"])
            .status()
            .expect("Failed to execute 'git submodule init'")
            .success()
            && Command::new("git")
                .args(["submodule", "update", "--recursive"])
                .status()
                .expect("Failed to execute 'git submodule update --recursive'")
                .success()
        {
            // Now, inside nwaku folder, run 'make update' to get nwaku's vendors
            let nwaku_path = project_dir.join("vendor");
            set_current_dir(nwaku_path).expect("Moving to vendor dir");

            if Command::new("make")
                .args(["update"])
                .status()
                .expect("Failed to execute 'make update'")
                .success()
            {
                std::fs::File::create(mark_file_path).expect("Failed to create mark file");
            } else {
                panic!("Failed to run 'make update' within nwaku folder.");
            }

            set_current_dir(project_dir).expect("Going back to project dir");

            println!("Git submodules initialized and updated successfully.");
        } else {
            panic!("Failed to initialize or update git submodules.");
        }
    } else {
        println!("Mark file '{mark_file_path}' exists. Skipping git submodule initialization.");
    }
}

fn build_nwaku_lib(project_dir: &Path) {
    let nwaku_path = project_dir.join("vendor");
    set_current_dir(nwaku_path).expect("Moving to vendor dir");

    let mut cmd = Command::new("make");
    cmd.arg("liblogosdelivery").arg("STATIC=1");
    let status = cmd
        .status()
        .unwrap_or_else(|e| panic!("Failed to run 'make liblogosdelivery': {e}"));

    // The exit status has to be checked, not just the spawn: a failed make would
    // otherwise pass silently and the crate would link a stale library from a
    // previous build.
    if !status.success() {
        panic!("'make liblogosdelivery STATIC=1' failed with {status}");
    }

    set_current_dir(project_dir).expect("Going back to project dir");
}

/// Resolves a package directory under the vendor's `nimbledeps/pkgs2`, whose
/// names carry a version and hash (e.g. `nat_traversal-0.0.1-1a376d3e...`) that
/// change whenever `nimble.lock` moves.
fn nimble_pkg_dir(nwaku_path: &Path, pkg_name: &str) -> PathBuf {
    let pkgs_dir = nwaku_path.join("nimbledeps/pkgs2");
    let prefix = format!("{pkg_name}-");
    std::fs::read_dir(&pkgs_dir)
        .unwrap_or_else(|e| panic!("Cannot read {}: {e}", pkgs_dir.display()))
        .filter_map(|entry| entry.ok())
        .map(|entry| entry.path())
        .find(|path| {
            path.file_name()
                .and_then(|name| name.to_str())
                .is_some_and(|name| name.starts_with(&prefix))
        })
        .unwrap_or_else(|| {
            panic!(
                "No '{pkg_name}' package under {}. Was 'make liblogosdelivery' run?",
                pkgs_dir.display()
            )
        })
}

/// Finds the vendor's `librln_<version>.a` and returns the name to link it by
/// (the file stem without the `lib` prefix).
fn find_librln(nwaku_path: &Path) -> String {
    std::fs::read_dir(nwaku_path)
        .unwrap_or_else(|e| panic!("Cannot read {}: {e}", nwaku_path.display()))
        .filter_map(|entry| entry.ok())
        .filter_map(|entry| entry.file_name().into_string().ok())
        .find_map(|name| {
            name.strip_prefix("lib")
                .and_then(|name| name.strip_suffix(".a"))
                .filter(|name| name.starts_with("rln"))
                .map(str::to_owned)
        })
        .unwrap_or_else(|| {
            panic!(
                "No 'librln_*.a' in {}. Was 'make librln' run?",
                nwaku_path.display()
            )
        })
}

fn emit_link_flags(project_dir: &Path) {
    let nwaku_path = project_dir.join("vendor");

    // The FFI surface is generated by the vendor's genBindings() rather than
    // bindgen, so the sources it emits are what invalidates this crate.
    println!(
        "cargo:rerun-if-changed={}",
        nwaku_path.join("library/rust_bindings/src").display()
    );
    // The Nim sources the library is built from have to invalidate it too, or
    // editing them leaves the linked archive stale and the tests silently run
    // against the previous build.
    println!(
        "cargo:rerun-if-changed={}",
        nwaku_path.join("library").display()
    );
    println!(
        "cargo:rerun-if-changed={}",
        nwaku_path.join("logos_delivery").display()
    );
    println!(
        "cargo:rustc-link-search={}",
        nwaku_path.join("build").display()
    );
    println!("cargo:rustc-link-lib=static=logosdelivery");

    // nat_traversal moved from a git submodule under vendor/ to a nimble
    // dependency, and builds its NAT archives inside its own package dir.
    let nat_traversal = nimble_pkg_dir(&nwaku_path, "nat_traversal");

    println!(
        "cargo:rustc-link-search={}",
        nat_traversal
            .join("vendor/miniupnp/miniupnpc/build")
            .display()
    );
    println!("cargo:rustc-link-lib=static=miniupnpc");

    println!(
        "cargo:rustc-link-search={}",
        nat_traversal.join("vendor/libnatpmp-upstream").display()
    );
    println!("cargo:rustc-link-lib=static=natpmp");

    println!("cargo:rustc-link-lib=dl");
    println!("cargo:rustc-link-lib=m");

    // boringssl (pulled in by libp2p) is C++, so its runtime has to be linked.
    if cfg!(target_os = "macos") {
        println!("cargo:rustc-link-lib=c++");
    } else {
        println!("cargo:rustc-link-lib=stdc++");
    }

    // The vendor's Makefile fetches librln into its root, naming it after the
    // RLN version it pins, so the archive is discovered rather than hardcoded.
    let librln = find_librln(&nwaku_path);
    println!("cargo:rustc-link-search={}", nwaku_path.display());
    println!("cargo:rustc-link-lib=static={librln}");

    // libbacktrace is not linked: the vendor builds with -d:disable_libbacktrace.

    cc::Build::new()
        .file("src/cmd.c") // Compile the C file
        .compile("cmditems"); // Compile it as a library
    println!("cargo:rustc-link-lib=static=cmditems");
}

#[cfg(not(doc))]
fn main() {
    let project_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());

    submodules_init(&project_dir);
    build_nwaku_lib(&project_dir);
    emit_link_flags(&project_dir);
}