#!/bin/bash
# {{ ansible_managed }}
# Collects transmission-daemon metrics for node_exporter textfile collector

set -euo pipefail

RPC_URL="http://{{ transmission_metrics_rpc_host }}:{{ transmission_metrics_rpc_port }}/transmission/rpc"
OUTPUT_FILE="{{ transmission_metrics_dir }}/transmission.prom"
TEMP_FILE="${OUTPUT_FILE}.tmp"

# Get session ID (required for transmission RPC)
# Note: transmission doesn't support HEAD requests, so we make a request and parse
# the 409 response headers. We use sed to stop at the blank line (which has \r) before body.
get_session_id() {
    curl -s -i "$RPC_URL" 2>/dev/null | sed '/^\r$/q' | grep -i '^X-Transmission-Session-Id:' | awk '{print $2}' | tr -d '\r'
}

# Make RPC request
rpc_request() {
    local method="$1"
    local args="${2:-}"
    local session_id
    session_id=$(get_session_id)

    if [ -z "$session_id" ]; then
        echo "Failed to get session ID" >&2
        return 1
    fi

    local payload
    if [ -n "$args" ]; then
        payload="{\"method\": \"$method\", \"arguments\": $args}"
    else
        payload="{\"method\": \"$method\"}"
    fi

    curl -s "$RPC_URL" \
        -H "X-Transmission-Session-Id: $session_id" \
        -H "Content-Type: application/json" \
        -d "$payload"
}

# Get session stats
session_stats=$(rpc_request "session-stats")

if [ -z "$session_stats" ] || ! echo "$session_stats" | grep -q '"result":"success"'; then
    echo "Failed to get session stats" >&2
    exit 1
fi

# Extract values using grep/sed (avoiding jq dependency)
extract_json_int() {
    echo "$1" | grep -o "\"$2\":[0-9]*" | head -1 | sed "s/\"$2\"://"
}

# Session stats
download_speed=$(extract_json_int "$session_stats" "downloadSpeed")
upload_speed=$(extract_json_int "$session_stats" "uploadSpeed")
torrents_active=$(extract_json_int "$session_stats" "activeTorrentCount")
torrents_paused=$(extract_json_int "$session_stats" "pausedTorrentCount")
torrents_total=$(extract_json_int "$session_stats" "torrentCount")

# Cumulative stats
downloaded_bytes=$(echo "$session_stats" | grep -o '"cumulative-stats":{[^}]*}' | grep -o '"downloadedBytes":[0-9]*' | sed 's/"downloadedBytes"://')
uploaded_bytes=$(echo "$session_stats" | grep -o '"cumulative-stats":{[^}]*}' | grep -o '"uploadedBytes":[0-9]*' | sed 's/"uploadedBytes"://')
seconds_active=$(echo "$session_stats" | grep -o '"cumulative-stats":{[^}]*}' | grep -o '"secondsActive":[0-9]*' | sed 's/"secondsActive"://')

# Get total size of all torrents
torrent_info=$(rpc_request "torrent-get" '{"fields": ["totalSize"]}')
total_size_bytes=0
if echo "$torrent_info" | grep -q '"result":"success"'; then
    # Sum all totalSize values
    total_size_bytes=$(echo "$torrent_info" | grep -o '"totalSize":[0-9]*' | sed 's/"totalSize"://' | awk '{sum += $1} END {print sum}')
fi

# Write metrics
cat > "$TEMP_FILE" << EOF
# HELP transmission_download_speed_bytes Current download speed in bytes per second
# TYPE transmission_download_speed_bytes gauge
transmission_download_speed_bytes ${download_speed:-0}

# HELP transmission_upload_speed_bytes Current upload speed in bytes per second
# TYPE transmission_upload_speed_bytes gauge
transmission_upload_speed_bytes ${upload_speed:-0}

# HELP transmission_torrents_active Number of active torrents
# TYPE transmission_torrents_active gauge
transmission_torrents_active ${torrents_active:-0}

# HELP transmission_torrents_paused Number of paused torrents
# TYPE transmission_torrents_paused gauge
transmission_torrents_paused ${torrents_paused:-0}

# HELP transmission_torrents_total Total number of torrents
# TYPE transmission_torrents_total gauge
transmission_torrents_total ${torrents_total:-0}

# HELP transmission_torrents_size_bytes Total size of all torrents in bytes
# TYPE transmission_torrents_size_bytes gauge
transmission_torrents_size_bytes ${total_size_bytes:-0}

# HELP transmission_downloaded_bytes_total Total bytes downloaded (cumulative)
# TYPE transmission_downloaded_bytes_total counter
transmission_downloaded_bytes_total ${downloaded_bytes:-0}

# HELP transmission_uploaded_bytes_total Total bytes uploaded (cumulative)
# TYPE transmission_uploaded_bytes_total counter
transmission_uploaded_bytes_total ${uploaded_bytes:-0}

# HELP transmission_seconds_active_total Total seconds transmission has been active
# TYPE transmission_seconds_active_total counter
transmission_seconds_active_total ${seconds_active:-0}

# HELP transmission_up Transmission daemon is up and responding
# TYPE transmission_up gauge
transmission_up 1
EOF

# Atomic move
mv "$TEMP_FILE" "$OUTPUT_FILE"