#!/usr/bin/env bash
# Assemble a signed APK from an already-built libdarkroom.so.
#
# This runs *inside* the Android image, where the SDK lives. It is deliberately
# separate from package.sh: package.sh is a host-side convenience that mounts
# the repo into a container and drives the whole build, while CI already runs
# in that image and needs only this half. Keeping the assembly in one file
# means the APK a device gets from `package.sh --install` and the APK CI
# publishes are built by the same code, rather than by two copies that drift.
#
# Everything is overridable, because the two callers disagree about paths: the
# container mounts the repo at /work, CI checks it out wherever the runner
# likes.
#
#   REPO         repo root                    (default: this script's ../..)
#   TARGET_DIR   cargo target directory       (default: $REPO/target-android)
#   JNILIBS      where cargo-ndk wrote the .so (default: $TARGET_DIR/jniLibs)
#   OUT          output directory             (default: $TARGET_DIR/apk)
#   KEYSTORE     signing keystore             (default: $TARGET_DIR/debug.keystore)
#   ABI          Android ABI                  (default: arm64-v8a)
#   RUST_TARGET  Rust target triple           (default: aarch64-linux-android)
#
# Signing. With none of these set the APK is debug-signed with a generated
# throwaway key, which is what a test device wants. Set all three for a real
# signature:
#
#   KEYSTORE_PASS  keystore password   — presence of this is what selects
#                                        release signing
#   KEY_PASS       key password        (default: same as KEYSTORE_PASS)
#   KEY_ALIAS      key alias within the store
#
# The passwords are read from the environment and handed to apksigner as
# `env:`, never `pass:`. `pass:` puts the password in the process table, where
# every other process on the machine can read it out of `ps`.
set -euo pipefail

HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

REPO="$(cd "${REPO:-${HERE}/../..}" && pwd)"
TARGET_DIR="${TARGET_DIR:-${REPO}/target-android}"
mkdir -p "${TARGET_DIR}"
TARGET_DIR="$(cd "${TARGET_DIR}" && pwd)"
JNILIBS="${JNILIBS:-${TARGET_DIR}/jniLibs}"
OUT="${OUT:-${TARGET_DIR}/apk}"
KEYSTORE="${KEYSTORE:-${TARGET_DIR}/debug.keystore}"

# Release signing is selected by supplying a password, not by a flag, so there
# is no way to ask for a release build and silently get a debug one.
if [[ -n "${KEYSTORE_PASS:-}" ]]; then
    SIGNING=release
    KEY_ALIAS="${KEY_ALIAS:?KEY_ALIAS is required when KEYSTORE_PASS is set}"
    export DR_KS_PASS="${KEYSTORE_PASS}"
    export DR_KEY_PASS="${KEY_PASS:-${KEYSTORE_PASS}}"
else
    SIGNING=debug
    KEY_ALIAS="androiddebugkey"
    export DR_KS_PASS=android
    export DR_KEY_PASS=android
fi
ABI="${ABI:-arm64-v8a}"
RUST_TARGET="${RUST_TARGET:-aarch64-linux-android}"

SDK="${ANDROID_HOME:-/opt/android-sdk}"

# Resolved rather than hard-coded: the versions live in the Dockerfile as ARGs,
# and a second copy here is a second thing to forget when they move. The newest
# installed build-tools wins.
BT="$(find "${SDK}/build-tools" -maxdepth 1 -mindepth 1 -type d | sort -V | tail -1)"
[[ -n "${BT}" ]] || { echo "error: no build-tools in ${SDK}" >&2; exit 1; }

# The Dockerfile sets ANDROID_JAR to the compile SDK; see its comment for why
# that is not the same number as MIN_API.
ANDROID_JAR="${ANDROID_JAR:-$(find "${SDK}/platforms" -maxdepth 1 -name 'android-*' \
    | sort -V | tail -1)/android.jar}"
[[ -f "${ANDROID_JAR}" ]] || { echo "error: no android.jar at ${ANDROID_JAR}" >&2; exit 1; }

# MIN_API comes from the Dockerfile too, so the manifest the device reads and
# the API the linker targeted cannot disagree.
MIN_API="$(sed -n 's/^ARG MIN_API=\([0-9]*\).*/\1/p' "${REPO}/docker/android/Dockerfile")"
[[ -n "${MIN_API}" ]] || { echo "error: no ARG MIN_API= in docker/android/Dockerfile" >&2; exit 1; }
TARGET_API="$(basename "$(dirname "${ANDROID_JAR}")" | sed 's/^android-//')"

# The version, taken from the workspace rather than restated here. See
# package.sh for why versionCode is packed the way it is.
VERSION_NAME="$(sed -n 's/^version = "\(.*\)"$/\1/p' "${REPO}/Cargo.toml" | head -1)"
[[ -n "${VERSION_NAME}" ]] || { echo "error: no version in Cargo.toml" >&2; exit 1; }
VERSION_CODE="$(awk -F. '{ print $1 * 10000 + $2 * 100 + $3 }' <<< "${VERSION_NAME}")"
echo "==> version ${VERSION_NAME} (code ${VERSION_CODE}), min API ${MIN_API}, target API ${TARGET_API}"

SO="${JNILIBS}/${ABI}/libdarkroom.so"
[[ -f "${SO}" ]] || { echo "error: ${SO} not built" >&2; exit 1; }

rm -rf "${OUT}"
mkdir -p "${OUT}/staging/lib/${ABI}"

# Slint compiles a Java helper (SlintAndroidJavaHelper) in its build script and
# dexes it. The build-dir hash changes whenever its inputs change, so find it
# rather than hard-coding a path; the newest wins if stale directories from
# earlier builds are still around.
DEX="$(find "${TARGET_DIR}/${RUST_TARGET}/release/build" \
    -path "*i-slint-backend-android-activity*/out/classes.dex" \
    -printf "%T@ %p\n" 2>/dev/null | sort -rn | head -1 | cut -d" " -f2-)"
[[ -n "${DEX}" ]] || { echo "error: Slint classes.dex not found — did the backend build?" >&2; exit 1; }
echo "    dex: ${DEX}"

# A debug keystore. CI points KEYSTORE at a throwaway directory so nothing is
# persisted or published; package.sh keeps one in the cache on purpose, because
# Android refuses to update an installed app whose signature changed and a new
# key every build would mean uninstalling before every install.
#
# Debug-signed only. This gets the app onto a test device; it is not a release
# signature, and the store password is the Android convention rather than a
# secret worth protecting.
if [[ "${SIGNING}" == "release" ]]; then
    # Never generated on demand. A release key is created once, by hand, and
    # kept; conjuring one here would mean every build signed by a different
    # identity, which is indistinguishable from having no signing story at all.
    [[ -f "${KEYSTORE}" ]] || {
        echo "error: KEYSTORE_PASS is set but ${KEYSTORE} does not exist" >&2
        exit 1
    }
    echo "    signing with the release key (alias ${KEY_ALIAS})"
elif [[ ! -f "${KEYSTORE}" ]]; then
    echo "    generating debug keystore"
    mkdir -p "$(dirname "${KEYSTORE}")"
    keytool -genkeypair -keystore "${KEYSTORE}" -alias "${KEY_ALIAS}" \
        -storepass:env DR_KS_PASS -keypass:env DR_KEY_PASS \
        -keyalg RSA -keysize 2048 -validity 10950 \
        -dname "CN=Android Debug,O=Android,C=US" >/dev/null 2>&1
fi

# The launcher icon is the only resource the app has, but resources go through
# aapt2 in two steps regardless: compile turns the source tree into an
# intermediate archive of flat files, link folds that into the APK and builds
# the resources.arsc table that @mipmap/ic_launcher in the manifest resolves
# against. Skipping compile and handing link the directory does not work — link
# only reads compiled input.
"${BT}/aapt2" compile \
    --dir "${REPO}/apps/darkroom-android/android/res" \
    -o "${OUT}/res.zip"

# `android:debuggable`, when asked for, and never otherwise.
#
# Without it `adb shell run-as` refuses — "package not debuggable" — and the
# app's own storage cannot be looked at from the host at all. That storage is
# where the face shards, the thumbnail store and the catalog live, so when a
# device disagrees with the desktop about what it has synced, there is no way
# to find out which of them is wrong.
#
# Set through aapt2 rather than in `AndroidManifest.xml` deliberately: the flag
# then exists only for the build that opted in, and a release build cannot
# inherit it by someone forgetting to take it back out again. A debuggable APK
# lets any process on the device read this app's private files, so it is a
# thing to install on a test tablet and not a thing to publish.
DEBUG_FLAG=()
if [ -n "${DARKROOM_DEBUGGABLE:-}" ]; then
    echo "==> debuggable build (run-as enabled; do not publish)"
    DEBUG_FLAG=(--debug-mode)
fi

"${BT}/aapt2" link \
    -I "${ANDROID_JAR}" \
    --manifest "${REPO}/apps/darkroom-android/android/AndroidManifest.xml" \
    -R "${OUT}/res.zip" \
    --min-sdk-version "${MIN_API}" \
    --target-sdk-version "${TARGET_API}" \
    --version-name "${VERSION_NAME}" \
    --version-code "${VERSION_CODE}" \
    "${DEBUG_FLAG[@]}" \
    -o "${OUT}/base.apk" \
    --auto-add-overlay

cp "${SO}" "${OUT}/staging/lib/${ABI}/libdarkroom.so"
cp "${DEX}" "${OUT}/staging/classes.dex"

# The face models. Android has no other route to one — app-private storage is
# not user-reachable and the in-app fetch is unbuilt (docs/faces.md §2.2a) — so
# they go in the APK and `android_main` unpacks them on first launch. The
# source is `models/face/`, shared with the Arch package rather than living
# under this one platform's directory.
#
# Through the staging directory rather than aapt2's `-A`: the .so and the dex
# already go in with `zip` below, and one mechanism for "extra files in the
# APK" is easier to follow than two.
ASSETS="${REPO}/models/face"
# Cleared first: a previous run that died between staging and cleanup would
# otherwise leave models in the APK that are no longer in the tree.
rm -rf "${OUT}/staging/assets"
if compgen -G "${ASSETS}/*.onnx" >/dev/null; then
    # An LFS pointer is ~130 bytes and looks exactly like a model to `cp`. Left
    # unchecked it reaches the device and fails inside tract, which reports a
    # broken graph rather than a clone that needs `git lfs pull`. Same guard
    # dr-segment's build script applies to yolo26n-seg.onnx, and the same
    # reason.
    for m in "${ASSETS}"/*.onnx; do
        if [[ "$(stat -c%s "${m}")" -lt 100000 ]]; then
            echo "error: $(basename "${m}") is $(stat -c%s "${m}") bytes — an LFS pointer, not a model." >&2
            echo "       run: git lfs pull" >&2
            exit 1
        fi
    done
    mkdir -p "${OUT}/staging/assets/models"
    cp "${ASSETS}"/*.onnx "${OUT}/staging/assets/models/"
    echo "    assets: $(ls "${ASSETS}" | grep '\.onnx$' | tr '\n' ' ')"
else
    echo "    assets: no face models found (face indexing will be off on the device)"
fi

# -0 "" stores the .so without compression so Android can mmap it directly
# (extractNativeLibs=false territory); for a 37 MB library that also keeps
# install times sane.
cd "${OUT}/staging"
cp "${OUT}/base.apk" "${OUT}/unaligned.apk"
zip -q -0 -X "${OUT}/unaligned.apk" "lib/${ABI}/libdarkroom.so"
zip -q -X "${OUT}/unaligned.apk" classes.dex
# Stored, not deflated: an ONNX graph is mostly incompressible float data, so
# deflating it buys a few percent and costs the whole file being inflated into
# RAM on the way out. AAssetManager reads a stored entry straight from the
# mapped APK.
if [[ -d assets ]]; then
    zip -q -0 -X -r "${OUT}/unaligned.apk" assets
fi

# zipalign before signing: apksigner preserves alignment, the reverse order
# invalidates the signature.
"${BT}/zipalign" -p -f 4 "${OUT}/unaligned.apk" "${OUT}/darkroom.apk"
"${BT}/apksigner" sign \
    --ks "${KEYSTORE}" --ks-key-alias "${KEY_ALIAS}" \
    --ks-pass env:DR_KS_PASS --key-pass env:DR_KEY_PASS \
    --min-sdk-version "${MIN_API}" \
    "${OUT}/darkroom.apk"
"${BT}/apksigner" verify --print-certs "${OUT}/darkroom.apk" | head -2
echo "    signing: ${SIGNING}"

# The intermediates are not the artefact, and leaving them beside it invites
# the wrong file being picked up by a glob.
rm -rf "${OUT}/staging" "${OUT}/res.zip" "${OUT}/base.apk" "${OUT}/unaligned.apk"

echo "==> ${OUT}/darkroom.apk"
ls -la "${OUT}/darkroom.apk"