#!/usr/bin/env bash
##
##  Script for generating bootstrap archives.
##

set -e

. $(dirname "$(realpath "$0")")/properties.sh
BOOTSTRAP_TMPDIR=$(mktemp -d "${TMPDIR:-/tmp}/bootstrap-tmp.XXXXXXXX")
trap 'rm -rf $BOOTSTRAP_TMPDIR' EXIT

# By default, bootstrap archives are compatible with Android >=7.0
# and <10.
BOOTSTRAP_ANDROID10_COMPATIBLE=false

# By default, bootstrap archives will be built for all architectures
# supported by Termux application.
# Override with option '--architectures'.
TERMUX_ARCHITECTURES=("aarch64" "arm" "i686" "x86_64")

# Can be changed by using '--repository' option.
REPO_BASE_URL="https://termux.org/packages"

# A list of non-essential packages. By default it is empty, but can
# be filled with option '--add'.
declare -a ADDITIONAL_PACKAGES

# Check for some important utilities that may not be available for
# some reason.
for cmd in ar awk curl grep gzip find sed tar xargs xz zip; do
	if [ -z "$(command -v $cmd)" ]; then
		echo "[!] Utility '$cmd' is not available in PATH."
		exit 1
	fi
done

# Download package lists from remote repository.
# Actually, there 2 lists can be downloaded: one architecture-independent and
# one for architecture specified as '$1' argument. That depends on repository.
# If repository has been created using "aptly", then architecture-independent
# list is not available.
read_package_list() {
	local architecture
	for architecture in all "$1"; do
		if [ ! -e "${BOOTSTRAP_TMPDIR}/packages.${architecture}" ]; then
			echo "[*] Downloading package list for architecture '${architecture}'..."
			if ! curl --fail --location \
				--output "${BOOTSTRAP_TMPDIR}/packages.${architecture}" \
				"${REPO_BASE_URL}/dists/stable/main/binary-${architecture}/Packages"; then
				if [ "$architecture" = "all" ]; then
					echo "[!] Skipping architecture-independent package list as not available..."
					continue
				fi
			fi
			echo >> "${BOOTSTRAP_TMPDIR}/packages.${architecture}"
		fi

		echo "[*] Reading package list for '${architecture}'..."
		while read -r -d $'\xFF' package; do
			if [ -n "$package" ]; then
				local package_name
				package_name=$(echo "$package" | grep -i "^Package:" | awk '{ print $2 }')

				if [ -z "${PACKAGE_METADATA["$package_name"]}" ]; then
					PACKAGE_METADATA["$package_name"]="$package"
				else
					local prev_package_ver cur_package_ver
					cur_package_ver=$(echo "$package" | grep -i "^Version:" | awk '{ print $2 }')
					prev_package_ver=$(echo "${PACKAGE_METADATA["$package_name"]}" | grep -i "^Version:" | awk '{ print $2 }')

					# If package has multiple versions, make sure that our metadata
					# contains the latest one.
					if [ "$(echo -e "${prev_package_ver}\n${cur_package_ver}" | sort -rV | head -n1)" = "${cur_package_ver}" ]; then
						PACKAGE_METADATA["$package_name"]="$package"
					fi
				fi
			fi
		done < <(sed -e "s/^$/\xFF/g" "${BOOTSTRAP_TMPDIR}/packages.${architecture}")
	done
}

# Download specified package, its depenencies and then extract *.deb files to
# the bootstrap root.
pull_package() {
	local package_name=$1
	local package_tmpdir="${BOOTSTRAP_PKGDIR}/${package_name}"
	mkdir -p "$package_tmpdir"

	local package_url
	package_url="$REPO_BASE_URL/$(echo "${PACKAGE_METADATA[${package_name}]}" | grep -i "^Filename:" | awk '{ print $2 }')"
	if [ "${package_url}" = "$REPO_BASE_URL" ] || [ "${package_url}" = "${REPO_BASE_URL}/" ]; then
		echo "[!] Failed to determine URL for package '$package_name'."
		exit 1
	fi

	local package_dependencies
	package_dependencies=$(
		while read -r token; do
			echo "$token" | cut -d'|' -f1 | sed -E 's@\(.*\)@@'
		done < <(echo "${PACKAGE_METADATA[${package_name}]}" | grep -i "^Depends:" | sed -E 's@^[Dd]epends:@@' | tr ',' '\n')
	)

	# Recursively handle dependencies.
	if [ -n "$package_dependencies" ]; then
		local dep
		for dep in $package_dependencies; do
			if [ ! -e "${BOOTSTRAP_PKGDIR}/${dep}" ]; then
				pull_package "$dep"
			fi
		done
		unset dep
	fi

	if [ ! -e "$package_tmpdir/package.deb" ]; then
		echo "[*] Downloading '$package_name'..."
		curl --fail --location --output "$package_tmpdir/package.deb" "$package_url"

		echo "[*] Extracting '$package_name'..."
		(cd "$package_tmpdir"
			ar x package.deb

			# data.tar may have extension different from .xz
			if [ -f "./data.tar.xz" ]; then
				data_archive="data.tar.xz"
			elif [ -f "./data.tar.gz" ]; then
				data_archive="data.tar.gz"
			else
				echo "No data.tar.* found in '$package_name'."
				exit 1
			fi

			# Do same for control.tar.
			if [ -f "./control.tar.xz" ]; then
				control_archive="control.tar.xz"
			elif [ -f "./control.tar.gz" ]; then
				control_archive="control.tar.gz"
			else
				echo "No control.tar.* found in '$package_name'."
				exit 1
			fi

			# Extract files.
			tar xf "$data_archive" -C "$BOOTSTRAP_ROOTFS"

			if ! ${BOOTSTRAP_ANDROID10_COMPATIBLE}; then
				# Register extracted files.
				tar tf "$data_archive" | sed -e 's@^\./@/@' -e 's@^/$@/.@' > "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/var/lib/dpkg/info/${package_name}.list"

				# Generate checksums (md5).
				tar xf "$data_archive"
				find data -type f -print0 | xargs -0 -r md5sum | sed 's@^\.$@@g' > "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/var/lib/dpkg/info/${package_name}.md5sums"

				# Extract metadata.
				tar xf "$control_archive"
				{
					cat control
					echo "Status: install ok installed"
					echo
				} >> "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/var/lib/dpkg/status"

				# Additional data: conffiles & scripts
				for file in conffiles postinst postrm preinst prerm; do
					if [ -f "${PWD}/${file}" ]; then
						cp "$file" "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/var/lib/dpkg/info/${package_name}.${file}"
					fi
				done
			fi
		)
	fi
}

# Final stage: generate bootstrap archive and place it to current
# working directory.
# Information about symlinks is stored in file SYMLINKS.txt.
create_bootstrap_archive() {
	echo "[*] Creating 'bootstrap-${1}.zip'..."
	(cd "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}"
		# Do not store symlinks in bootstrap archive.
		# Instead, put all information to SYMLINKS.txt
		while read -r -d '' link; do
			echo "$(readlink "$link")←${link}" >> SYMLINKS.txt
			rm -f "$link"
		done < <(find . -type l -print0)

		zip -r9 "${BOOTSTRAP_TMPDIR}/bootstrap-${1}.zip" ./*
	)

	mv -f "${BOOTSTRAP_TMPDIR}/bootstrap-${1}.zip" ./
	echo "[*] Finished successfully (${1})."
}

show_usage() {
	echo
	echo "Usage: generate-bootstraps.sh [options]"
	echo
	echo "Generate bootstrap archives for Termux application."
	echo
	echo "Options:"
	echo
	echo " -h, --help                  Show this help."
	echo
	echo " --android10                 Generate bootstrap archives for Android 10."
	echo
	echo " -a, --add PKG_LIST          Specify one or more additional packages"
	echo "                             to include into bootstrap archive."
	echo "                             Multiple packages should be passed as"
	echo "                             comma-separated list."
	echo
	echo " --architectures ARCH_LIST   Override default list of architectures"
	echo "                             for which bootstrap archives will be"
	echo "                             created."
	echo "                             Multiple architectures should be passed"
	echo "                             as comma-separated list."
	echo
	echo " -r, --repository URL        Specify URL for APT repository from"
	echo "                             which packages will be downloaded."
	echo
	echo "Architectures: ${TERMUX_ARCHITECTURES[*]}"
	echo "Repository URL: ${REPO_BASE_URL}"
	echo "Prefix: ${TERMUX_PREFIX}"
	echo
}

while (($# > 0)); do
	case "$1" in
		-h|--help)
			show_usage
			exit 0
			;;
		--android10)
			BOOTSTRAP_ANDROID10_COMPATIBLE=true
			;;
		-a|--add)
			if [ $# -gt 1 ] && [ -n "$2" ] && [[ $2 != -* ]]; then
				for pkg in $(echo "$2" | tr ',' ' '); do
					ADDITIONAL_PACKAGES+=("$pkg")
				done
				unset pkg
				shift 1
			else
				echo "[!] Option '--add' requires an argument."
				show_usage
				exit 1
			fi
			;;
		--architectures)
			if [ $# -gt 1 ] && [ -n "$2" ] && [[ $2 != -* ]]; then
				TERMUX_ARCHITECTURES=()
				for arch in $(echo "$2" | tr ',' ' '); do
					TERMUX_ARCHITECTURES+=("$arch")
				done
				unset arch
				shift 1
			else
				echo "[!] Option '--architectures' requires an argument."
				show_usage
				exit 1
			fi
			;;
		-r|--repository)
			if [ $# -gt 1 ] && [ -n "$2" ] && [[ $2 != -* ]]; then
				REPO_BASE_URL="$2"
				shift 1
			else
				echo "[!] Option '--repository' requires an argument."
				show_usage
				exit 1
			fi
			;;
		*)
			echo "[!] Got unknown option '$1'"
			show_usage
			exit 1
			;;
	esac
	shift 1
done

for package_arch in "${TERMUX_ARCHITECTURES[@]}"; do
	BOOTSTRAP_ROOTFS="$BOOTSTRAP_TMPDIR/rootfs-${package_arch}"
	BOOTSTRAP_PKGDIR="$BOOTSTRAP_TMPDIR/packages-${package_arch}"

	# Create initial directories for $TERMUX_PREFIX
	if ! ${BOOTSTRAP_ANDROID10_COMPATIBLE}; then
		mkdir -p "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/etc/apt/apt.conf.d"
		mkdir -p "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/etc/apt/preferences.d"
		mkdir -p "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/var/lib/dpkg/info"
		mkdir -p "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/var/lib/dpkg/triggers"
		mkdir -p "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/var/lib/dpkg/updates"
		mkdir -p "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/var/log/apt"
		touch "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/var/lib/dpkg/available"
		touch "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/var/lib/dpkg/status"
	fi
	mkdir -p "${BOOTSTRAP_ROOTFS}/${TERMUX_PREFIX}/tmp"

	# Read package metadata.
	unset PACKAGE_METADATA
	declare -A PACKAGE_METADATA
	read_package_list "$package_arch"

	# Package manager.
	if ! ${BOOTSTRAP_ANDROID10_COMPATIBLE}; then
		pull_package apt
		pull_package game-repo
		pull_package science-repo
	fi

	# Core utilities.
	pull_package bash
	pull_package bzip2
	if ! ${BOOTSTRAP_ANDROID10_COMPATIBLE}; then
		pull_package command-not-found
	else
		pull_package proot
	fi
	pull_package coreutils
	pull_package curl
	pull_package dash
	pull_package diffutils
	pull_package findutils
	pull_package gawk
	pull_package grep
	pull_package gzip
	pull_package less
	pull_package procps
	pull_package psmisc
	pull_package sed
	pull_package tar
	pull_package termux-exec
	pull_package termux-tools
	pull_package util-linux
	pull_package xz-utils

	# Additional.
	pull_package ed
	pull_package debianutils
	pull_package dos2unix
	pull_package inetutils
	pull_package lsof
	pull_package nano
	pull_package net-tools
	pull_package patch
	pull_package unzip

	# Handle additional packages.
	for add_pkg in "${ADDITIONAL_PACKAGES[@]}"; do
		pull_package "$add_pkg"
	done
	unset add_pkg

	# Create bootstrap archive.
	create_bootstrap_archive "$package_arch"
done