#!/usr/bin/env bash
set -euo pipefail

usage() {
    echo "Usage: $0 --payload-dir DIR --entrypoint FILE [--output FILE]"
    echo "       $0 -p DIR -e FILE [-o FILE]"
    exit 1
}

# 📥 Default values
HEADER="sfx_header.sh"
PAYLOAD_DIR=""
ENTRYPOINT=""
OUTPUT="sfx.run"

# 📋 Process arguments
while [[ $# -gt 0 ]]; do
    case "$1" in
        --payload-dir|-p)
            PAYLOAD_DIR="$2"
            shift 2
            ;;
        --entrypoint|-e)
            ENTRYPOINT="$2"
            shift 2
            ;;
        --output|-o)
            OUTPUT="$2"
            shift 2
            ;;
        *)
            echo "❌ Unknown option: $1" >&2
            usage
            ;;
    esac
done

# ✅ Validation
[[ -z "$PAYLOAD_DIR" || -z "$ENTRYPOINT" ]] && usage
[[ ! -d "$PAYLOAD_DIR" ]] && { echo "❌ Payload directory not found: $PAYLOAD_DIR" >&2; exit 1; }
[[ ! -f "$PAYLOAD_DIR/$ENTRYPOINT" ]] && { echo "❌ Entrypoint not found in payload: $ENTRYPOINT" >&2; exit 1; }

# 🧊 Temporary directory
BUILD_TMP="$(mktemp -d "${TMPDIR:-/tmp}/sfxbuild.XXXXXX")"
PAYLOAD_ARCHIVE="$BUILD_TMP/payload.tar.zst"
HEADER_TMP="$BUILD_TMP/sfx_header.final"

cleanup() {
    rm -rf "$BUILD_TMP"
}
trap cleanup EXIT

echo "📦 Creating payload (→ $PAYLOAD_ARCHIVE)..."
tar -cf - -C "$PAYLOAD_DIR" . | tee >(wc -c > "$BUILD_TMP/raw_size") | zstd -19 -T0 -o "$PAYLOAD_ARCHIVE"
RAW_SIZE=$(numfmt --to=iec < "$BUILD_TMP/raw_size")

# 🧭 Find marker
ARCHIVE_LINE=$(grep -n '^__ARCHIVE_BEGIN__$' "$HEADER" | cut -d: -f1)
[[ ! "$ARCHIVE_LINE" =~ ^[0-9]+$ ]] && {
    echo "❌ Error: Marker __ARCHIVE_BEGIN__ not found!" >&2
    exit 1
}
echo "🧮 Archive starts from line $ARCHIVE_LINE"

# 🛠️ Replace placeholders
sed "s|__ARCHIVE_LINE__|$ARCHIVE_LINE|" "$HEADER" | \
sed "s|__ENTRYPOINT__|$ENTRYPOINT|" | \
sed '/^__ARCHIVE_BEGIN__$/d' > "$HEADER_TMP"

# 🔗 Combine
cat "$HEADER_TMP" "$PAYLOAD_ARCHIVE" > "$OUTPUT"
chmod +x "$OUTPUT"

# 📊 Output
FINAL_SIZE=$(du -h "$OUTPUT" | cut -f1)
echo "✅ Done: $OUTPUT"
echo "   📁 Original size: $RAW_SIZE"
echo "   📦 Output file: $FINAL_SIZE"