#!/usr/bin/env bash
# scripts/build-boringtun.sh — Build the boringtun WireGuard FFI library for Artemis.
#
# Usage:
#   bash scripts/build-boringtun.sh              # native target
#   bash scripts/build-boringtun.sh --universal  # macOS fat binary (x86_64 + arm64)
#
# Output:
#   deps/boringtun/libboringtun.a   — static library
#   deps/boringtun/wireguard_ffi.h  — C ABI header (for reference)
#
# Prerequisites:
#   • Rust toolchain  (https://rustup.rs)
#   • git

set -euo pipefail

REPO="https://github.com/cloudflare/boringtun.git"
ROOT="$(cd "$(dirname "$0")/.." && pwd)"
SRC="$ROOT/build/boringtun-src"
OUT="$ROOT/deps/boringtun"
UNIVERSAL=false

while [[ $# -gt 0 ]]; do
    case "$1" in
        --universal) UNIVERSAL=true; shift ;;
        *) echo "Unknown flag: $1"; exit 1 ;;
    esac
done

info()  { echo "  $*"; }
ok()    { echo "  ✓ $*"; }
fail()  { echo "  ✗ $*" >&2; exit 1; }

# ── Prerequisites ─────────────────────────────────────────────────────────────

command -v cargo &>/dev/null || fail "cargo not found. Install Rust from https://rustup.rs"
command -v git   &>/dev/null || fail "git not found"

if $UNIVERSAL; then
    rustup target add x86_64-apple-darwin aarch64-apple-darwin 2>/dev/null || true
fi

# ── Clone / update ────────────────────────────────────────────────────────────

if [[ ! -d "$SRC" ]]; then
    info "Cloning boringtun..."
    git clone --depth 1 "$REPO" "$SRC"
else
    info "Updating boringtun..."
    git -C "$SRC" pull --ff-only
fi
ok "Source ready"

# ── Build ─────────────────────────────────────────────────────────────────────

if $UNIVERSAL && [[ "$(uname)" == "Darwin" ]]; then
    info "Building for x86_64-apple-darwin..."
    (cd "$SRC" && cargo build --release --target x86_64-apple-darwin --features ffi-bindings)
    info "Building for aarch64-apple-darwin..."
    (cd "$SRC" && cargo build --release --target aarch64-apple-darwin --features ffi-bindings)
    ok "Both slices built"
else
    info "Building boringtun (release)..."
    (cd "$SRC" && cargo build --release --features ffi-bindings)
    ok "Build complete"
fi

# ── Copy artifacts ────────────────────────────────────────────────────────────

mkdir -p "$OUT"

if $UNIVERSAL && [[ "$(uname)" == "Darwin" ]]; then
    X86="$SRC/target/x86_64-apple-darwin/release/libboringtun.a"
    ARM="$SRC/target/aarch64-apple-darwin/release/libboringtun.a"
    [[ -f "$X86" ]] || fail "x86_64 library not found: $X86"
    [[ -f "$ARM" ]] || fail "arm64 library not found:  $ARM"
    lipo -create "$X86" "$ARM" -output "$OUT/libboringtun.a"
    ok "Created universal fat binary"
else
    LIB="$SRC/target/release/libboringtun.a"
    [[ -f "$LIB" ]] || fail "Library not found: $LIB"
    cp "$LIB" "$OUT/libboringtun.a"
    ok "Copied libboringtun.a"
fi

# Copy reference header if present
HDR="$SRC/boringtun/src/ffi/wireguard_ffi.h"
if [[ -f "$HDR" ]]; then
    cp "$HDR" "$OUT/wireguard_ffi.h"
    ok "Copied wireguard_ffi.h"
fi

echo ""
echo "  Build successful.  Library at:"
echo "    $OUT/libboringtun.a"
echo ""
echo "  Next: cmake -B build && cmake --build build"