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

readonly SOURCE_COMMIT=eb20e88f582e1ddb0f32e8acf90cd9e77ec63b8f
readonly SOURCE_TREE=be6cf1d033f17ab53f23e5b8e5c7f4492f18e2f8
readonly PATCHED_TREE=29e47624ba86572d278411d229e24f4822046021
readonly SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
readonly PATCH_FILE="$SCRIPT_DIR/podsteadr-archipelago.patch"

if [[ $# -ne 2 ]]; then
  echo "usage: $0 SOURCE_GIT_DIR NEW_OUTPUT_DIR" >&2
  exit 2
fi

source_git=$(cd "$1" && pwd)
output_parent=$(cd "$(dirname "$2")" && pwd)
output="$output_parent/$(basename "$2")"

[[ ! -e "$output" ]] || {
  echo "refusing to overwrite existing output: $output" >&2
  exit 2
}

actual_tree=$(git -C "$source_git" rev-parse "$SOURCE_COMMIT^{tree}")
[[ "$actual_tree" == "$SOURCE_TREE" ]] || {
  echo "source tree mismatch for $SOURCE_COMMIT" >&2
  exit 1
}

staging=$(mktemp -d "$output_parent/.podsteadr-source.XXXXXX")
trap 'rm -rf -- "$staging"' EXIT

git -C "$source_git" archive "$SOURCE_COMMIT" | tar -x -C "$staging"
git -C "$staging" init -q
git -C "$staging" apply --check "$PATCH_FILE"
git -C "$staging" apply "$PATCH_FILE"
git -C "$staging" apply --check "$SCRIPT_DIR/podsteadr-lifecycle.patch"
git -C "$staging" apply "$SCRIPT_DIR/podsteadr-lifecycle.patch"
git -C "$staging" apply --check "$SCRIPT_DIR/podsteadr-responsive.patch"
git -C "$staging" apply "$SCRIPT_DIR/podsteadr-responsive.patch"
git -C "$staging" apply --check "$SCRIPT_DIR/podsteadr-native-bridge.patch"
git -C "$staging" apply "$SCRIPT_DIR/podsteadr-native-bridge.patch"
git -C "$staging" apply --check "$SCRIPT_DIR/podsteadr-server-key.patch"
git -C "$staging" apply "$SCRIPT_DIR/podsteadr-server-key.patch"
git -C "$staging" add -A
patched_tree=$(git -C "$staging" write-tree)
[[ "$patched_tree" == "$PATCHED_TREE" ]] || {
  echo "patched tree mismatch" >&2
  exit 1
}
# The temporary repository exists only to calculate the exact patched tree. Do
# not carry Git metadata or a source remote into the image build context.
rm -rf -- "$staging/.git"
printf '%s\n' "$SOURCE_COMMIT" > "$staging/.archipelago-source-commit"
printf '%s\n' "$SOURCE_TREE" > "$staging/.archipelago-source-tree"
printf '%s\n' "$patched_tree" > "$staging/.archipelago-patched-tree"

mv "$staging" "$output"
trap - EXIT
printf 'prepared Podsteadr %s as tree %s\n' "$SOURCE_COMMIT" "$patched_tree"