#!/bin/bash

# Default values
NC_URL="${NC_TALK_URL:-https://cloud.ids-mannheim.de}"
CONVERSATION="${NC_TALK_CONVERSATION:-o6toyqx7}"
SECRET="${NC_TALK_SECRET}"
MESSAGE=""
DEBUG=false
SILENT=false

# Function to display help
show_help() {
    cat << EOF
Usage: $(basename "$0") [OPTIONS] [message]

Sends <message> to a Nextcloud Talk room. Use - for reading message from stdin

Options:
    -h, --help                    Show this help message
    -d, --debug                   Output extra debugging
    -c, --conversation <token>    Send message to conversation (default: o6toyqx7)
    -s, --secret <secret>         Bot secret
    -u, --url <url>               Nextcloud URL (default: https://cloud.ids-mannheim.de)
    --silent                      Send message silently (no notification)

Environment variables:
    NC_TALK_URL             Nextcloud URL
    NC_TALK_CONVERSATION    Conversation token
    NC_TALK_SECRET          Bot secret

EOF
    exit 0
}

# Parse command line arguments
while [[ $# -gt 0 ]]; do
    case $1 in
        -h|--help)
            show_help
            ;;
        -d|--debug)
            DEBUG=true
            shift
            ;;
        -c|--conversation)
            CONVERSATION="$2"
            shift 2
            ;;
        -s|--secret)
            SECRET="$2"
            shift 2
            ;;
        -u|--url)
            NC_URL="$2"
            shift 2
            ;;
        --silent)
            SILENT=true
            shift
            ;;
        -*)
            echo "Unknown option: $1" >&2
            show_help
            ;;
        *)
            MESSAGE="$1"
            shift
            ;;
    esac
done

# Check if we should read from stdin (before consuming stdin)
if [[ -z "$MESSAGE" ]] || [[ "$MESSAGE" == "-" ]]; then
    if [[ "$DEBUG" == true ]]; then
        echo "Reading from stdin" >&2
    fi
    # Read from stdin and wrap in code blocks like slack.js
    MESSAGE=$'```\n'"$(cat)"$'\n```'
fi

# Check required parameters
if [[ -z "$CONVERSATION" ]]; then
    echo "Error: Conversation token is required. Use -c/--conversation option or set NC_TALK_CONVERSATION environment variable." >&2
    exit 1
fi

if [[ -z "$SECRET" ]]; then
    echo "Error: Bot secret is required. Use -s/--secret option or set NC_TALK_SECRET environment variable." >&2
    exit 1
fi

if [[ -z "$MESSAGE" ]]; then
    echo "Error: Message is required." >&2
    exit 1
fi

if [[ "$DEBUG" == true ]]; then
    echo "URL: $NC_URL" >&2
    echo "Conversation: $CONVERSATION" >&2
    echo "Message: $MESSAGE" >&2
    echo "Silent: $SILENT" >&2
fi

# Generate a random header and signature
RANDOM_HEADER=$(openssl rand -hex 32)
MESSAGE_TO_SIGN="${RANDOM_HEADER}${MESSAGE}"
SIGNATURE=$(echo -n "${MESSAGE_TO_SIGN}" | openssl dgst -sha256 -hmac "${SECRET}" | cut -d' ' -f2)

# Escape the message for JSON (replace backslashes, quotes, and newlines)
MESSAGE_ESCAPED=$(echo -n "$MESSAGE" | jq -Rs .)

# Send the message
curl -X POST \
"${NC_URL}/ocs/v2.php/apps/spreed/api/v1/bot/${CONVERSATION}/message" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -H "OCS-APIRequest: true" \
  -H "X-Nextcloud-Talk-Bot-Random: ${RANDOM_HEADER}" \
  -H "X-Nextcloud-Talk-Bot-Signature: ${SIGNATURE}" \
  -d '{"message":'"${MESSAGE_ESCAPED}"',"silent":'"$SILENT"'}'