#!/bin/bash

# ============================================================================
# Hand the bot's profile key to somebody who is about to add it to a group.
#
# Signal only adds an account to a group outright when whoever adds it
# already holds that account's profile key. Otherwise the add silently
# becomes a pending invitation -- and signal-cli cannot accept an invite
# addressed to a phone number, so the bot sits in the group forever,
# looking healthy and receiving nothing.
#
# Sending one direct message from the bot to that person hands their client
# the profile key, so the add that follows lands as a real join. Run this
# BEFORE asking anyone to add the bot to an existing group.
#
# Usage: scripts/prime_profile.sh +48123456789 [+48987654321 ...]
# ============================================================================

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
readonly SCRIPT_DIR
REPO_ROOT="$(dirname "$SCRIPT_DIR")"
readonly REPO_ROOT
SCRIPT_NAME="$(basename "$0")"
readonly SCRIPT_NAME

readonly PORT="${PORT:-9922}"
readonly API="${API:-http://localhost:${PORT}}"
readonly BOT_NAME="${BOT_NAME:-signal-bot}"
readonly MESSAGE="${MESSAGE:-Hi, I am ${BOT_NAME}. Adding me to a group now works: this message gave your phone my profile, so the add becomes a real join instead of an invite I cannot accept.}"

RECIPIENTS=()

# shellcheck source-path=SCRIPTDIR source=scripts/lib_signal.sh
. "${SCRIPT_DIR}/lib_signal.sh"

# Prints only. The caller decides the exit code, so a usage *error* cannot
# exit 0 and be read as success by whatever ran this.
usage() {
	echo "Usage: ${SCRIPT_NAME} +<E164 number> [+<E164 number> ...]"
	echo "Sends one DM from the bot so the recipient's client learns its"
	echo "profile key, which makes a later group add land as a real join."
}

validate_requirements() {
	command -v curl >/dev/null || { echo "Error: curl is required" >&2; exit 1; }
	command -v jq >/dev/null || { echo "Error: jq is required" >&2; exit 1; }
	if [[ ${#RECIPIENTS[@]} -eq 0 ]]; then
		echo "Error: at least one recipient number is required" >&2
		usage >&2
		exit 1
	fi
	local number
	for number in "${RECIPIENTS[@]}"; do
		if [[ ! "$number" =~ ^\+[0-9]{6,15}$ ]]; then
			echo "Error: '${number}' is not an E.164 number like +48123456789" >&2
			exit 1
		fi
	done
	if [[ ! -f "${REPO_ROOT}/.env" ]]; then
		echo "Error: no ${REPO_ROOT}/.env -- run scripts/register_bot.sh first" >&2
		exit 1
	fi
}

# Read the bot's own number out of .env rather than asking for it: a number
# typed twice is a number that can be typed differently the second time.
bot_number() {
	local number
	# `|| true`: under `set -e` a grep that matches nothing kills the whole
	# subshell, so the error message below would never print and the script
	# would exit 1 silently -- the failure mode this repo exists to gate.
	number="$(grep -E '^PHONE_NUMBER=' "${REPO_ROOT}/.env" || true)"
	number="$(printf '%s' "$number" | head -1 | cut -d= -f2-)"
	if [[ -z "$number" ]]; then
		echo "Error: PHONE_NUMBER is not set in ${REPO_ROOT}/.env" >&2
		return 1
	fi
	printf '%s' "$number"
}

send_dm() {
	local from="$1" to="$2" status
	status="$(curl -sS -o /dev/null -w '%{http_code}' -X POST "${API}/v2/send" \
		-H 'Content-Type: application/json' \
		-d "$(jq -n --arg msg "$MESSAGE" --arg from "$from" --arg to "$to" \
			'{message: $msg, number: $from, recipients: [$to]}')")"
	if [[ "$status" != "2"* ]]; then
		echo "Error: could not message ${to} (HTTP ${status})." >&2
		return 1
	fi
	echo "== ${to} now has the bot's profile key"
}

main() {
	validate_requirements

	local number
	number="$(bot_number)"
	signal_wait_for_url "${API}/v1/about" "signal-cli-rest-api" 25
	signal_verify_mode
	# The profile is re-asserted rather than assumed: an account with no
	# profile hands over nothing, so the DM would leave the recipient in
	# exactly the state this script exists to prevent.
	signal_set_profile "$number" "$BOT_NAME"

	local recipient
	for recipient in "${RECIPIENTS[@]}"; do
		send_dm "$number" "$recipient"
	done

	echo "== done. Ask them to add ${number} to the group now."
	echo "   Then add the group id to GROUP_IDS in .env and restart:"
	echo "   systemctl --user restart signal-bot.service"
}

while [[ $# -gt 0 ]]; do
	case $1 in
		-h | --help)
			usage
			exit 0
			;;
		-*)
			echo "Unknown option: $1" >&2
			exit 1
			;;
		*)
			RECIPIENTS+=("$1")
			shift
			;;
	esac
done

main "$@"