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

ALPINE_VERSION="v3.23"
PACKAGES=("bash" "curl" "jq" "git" "docker")
REPOS=("main" "community")
BASE_URL="https://dl-cdn.alpinelinux.org/alpine"
DEST_DIR="."
ARCHES=("x86_64" "aarch64" "armv7") # only mirror the arches you care about
CURL_OPTS="-fSL --retry 3 --retry-delay 2 --connect-timeout 10"

mkdir -p "$DEST_DIR"

# Function to download a single package and its deps for a given arch
download_pkg() {
    local pkg="$1"
    local arch="$2"
    local found=false

    for repo in "${REPOS[@]}"; do
        local index_url="${BASE_URL}/${ALPINE_VERSION}/${repo}/${arch}/APKINDEX.tar.gz"
        local tmpdir
        tmpdir=$(mktemp -d)
        trap "rm -rf $tmpdir" EXIT

        echo "📥 Fetching APKINDEX: $index_url"
        if ! curl $CURL_OPTS "$index_url" -o "$tmpdir/APKINDEX.tar.gz"; then
            echo "⚠️ Failed to fetch $index_url, skipping."
            continue
        fi

        tar -xzf "$tmpdir/APKINDEX.tar.gz" -C "$tmpdir"

        # Extract version for the package
        local version
        version=$(grep -A1 "^P:${pkg}$" "$tmpdir"/APKINDEX | grep "^V:" | cut -d':' -f2 | sed 's/^[ \t]*//;s/[ \t]*$//' || true)

        if [ -z "$version" ]; then
            continue
        fi

        local file="${pkg}-${version}.apk"
        local out_dir="${DEST_DIR}/${ALPINE_VERSION}/${arch}"
        mkdir -p "$out_dir"

        if [ ! -f "$out_dir/$file" ]; then
            echo "🔽 Downloading $file for arch $arch from $repo"
            curl $CURL_OPTS "${BASE_URL}/${ALPINE_VERSION}/${repo}/${arch}/${file}" -o "$out_dir/$file"
        else
            echo "ℹ️ $file already exists for arch $arch, skipping download."
        fi

        found=true

        # Handle dependencies
        local deps
        deps=$(grep -A10 "^P:${pkg}$" "$tmpdir"/APKINDEX | grep "^D:" | cut -d':' -f2- | sed 's/^[ \t]*//' || true)
        for dep in $deps; do
            # Strip version constraints (e.g., >1.0, =2.0) to get base dep name
            dep_name=$(echo "$dep" | sed 's/[><=].*//;s/so://')
            if [ -n "$dep_name" ] && [ "$dep_name" != "$pkg" ]; then
                download_pkg "$dep_name" "$arch"
            fi
        done

        break  # Stop after finding in one repo
    done

    if ! $found; then
        echo "⚠️ Package not found: $pkg for arch $arch"
    fi
}

for arch in "${ARCHES[@]}"; do
    echo "=============================="
    echo "📦 Processing architecture: $arch"
    echo "=============================="
    for pkg in "${PACKAGES[@]}"; do
        download_pkg "$pkg" "$arch"
    done
done

echo
echo "✅ Done! Packages saved under: ${DEST_DIR}/${ALPINE_VERSION}/"