#!/usr/bin/env bash
#
# stack-logs.sh - Get logs for a stack service/container
#
# Usage: stack-logs.sh -n <stack-name> [-s service-name] [-t tail] [-f]
#
# Environment variables:
#   PORTAINER_URL     - Portainer instance URL (e.g., https://portainer.example.com:9443)
#   PORTAINER_API_KEY - API access token
#
# Options:
#   -n name           Stack name (required)
#   -s service        Service/container name (optional - if omitted, lists available services)
#   -t tail           Number of lines to show from the end (default: 100)
#   -f                Follow log output (stream logs)
#   --timestamps      Show timestamps
#   -h                Show this help

set -euo pipefail

# Default values
STACK_NAME=""
SERVICE_NAME=""
TAIL_LINES="100"
FOLLOW=false
TIMESTAMPS=false

# Parse arguments
while [[ $# -gt 0 ]]; do
    case $1 in
        -n) STACK_NAME="$2"; shift 2 ;;
        -s) SERVICE_NAME="$2"; shift 2 ;;
        -t) TAIL_LINES="$2"; shift 2 ;;
        -f) FOLLOW=true; shift ;;
        --timestamps) TIMESTAMPS=true; shift ;;
        -h|--help)
            head -20 "$0" | grep "^#" | sed 's/^# \?//'
            exit 0
            ;;
        *)
            echo "Unknown option: $1" >&2
            echo "Usage: $0 -n <stack-name> [-s service-name] [-t tail] [-f]" >&2
            exit 1
            ;;
    esac
done

# Validate environment
if [[ -z "${PORTAINER_URL:-}" ]]; then
    echo "Error: PORTAINER_URL environment variable not set" >&2
    exit 1
fi

if [[ -z "${PORTAINER_API_KEY:-}" ]]; then
    echo "Error: PORTAINER_API_KEY environment variable not set" >&2
    exit 1
fi

if [[ -z "$STACK_NAME" ]]; then
    echo "Error: -n <stack-name> is required" >&2
    exit 1
fi

# Remove trailing slash from URL
PORTAINER_URL="${PORTAINER_URL%/}"

# Function to make API requests
api_request() {
    local method="$1"
    local endpoint="$2"

    curl -s -w "\n%{http_code}" -X "$method" \
        -H "X-API-Key: ${PORTAINER_API_KEY}" \
        "${PORTAINER_URL}${endpoint}"
}

# Get stack info by name
response=$(api_request GET "/api/stacks")
http_code=$(echo "$response" | tail -n1)
body=$(echo "$response" | sed '$d')

if [[ "$http_code" != "200" ]]; then
    echo "Error: Failed to list stacks (HTTP $http_code)" >&2
    exit 1
fi

stack_info=$(echo "$body" | jq --arg name "$STACK_NAME" '.[] | select(.Name == $name)')

if [[ -z "$stack_info" || "$stack_info" == "null" ]]; then
    echo "Error: Stack '$STACK_NAME' not found" >&2
    exit 1
fi

ENDPOINT_ID=$(echo "$stack_info" | jq -r '.EndpointId')

# Get containers for this stack
response=$(api_request GET "/api/endpoints/${ENDPOINT_ID}/docker/containers/json?all=true")
http_code=$(echo "$response" | tail -n1)
body=$(echo "$response" | sed '$d')

if [[ "$http_code" != "200" ]]; then
    echo "Error: Failed to get containers (HTTP $http_code)" >&2
    exit 1
fi

# Filter containers belonging to this stack
containers=$(echo "$body" | jq --arg name "$STACK_NAME" '[.[] | select(
    (.Labels["com.docker.compose.project"] == $name) or
    (.Labels["com.docker.stack.namespace"] == $name)
)]')

container_count=$(echo "$containers" | jq 'length')

if [[ "$container_count" -eq 0 ]]; then
    echo "Error: No containers found for stack '$STACK_NAME'" >&2
    exit 1
fi

# If no service specified, list available services
if [[ -z "$SERVICE_NAME" ]]; then
    echo "Available services in stack '$STACK_NAME':"
    echo ""
    echo "$containers" | jq -r '.[] |
        (.Labels["com.docker.compose.service"] // .Labels["com.docker.swarm.service.name"] // .Names[0]) as $svc |
        "\(.Names[0] | ltrimstr("/")) (\($svc // "unknown"))"'
    echo ""
    echo "Use -s <service-name> to view logs for a specific service."
    exit 0
fi

# Find container matching service name
# Match against service label or container name
container=$(echo "$containers" | jq --arg svc "$SERVICE_NAME" 'first(.[] | select(
    (.Labels["com.docker.compose.service"] == $svc) or
    (.Labels["com.docker.swarm.service.name"] == $svc) or
    (.Names[] | contains($svc))
))')

if [[ -z "$container" || "$container" == "null" ]]; then
    echo "Error: Service '$SERVICE_NAME' not found in stack '$STACK_NAME'" >&2
    echo ""
    echo "Available services:"
    echo "$containers" | jq -r '.[] |
        .Labels["com.docker.compose.service"] // .Labels["com.docker.swarm.service.name"] // .Names[0]'
    exit 1
fi

CONTAINER_ID=$(echo "$container" | jq -r '.Id')
CONTAINER_NAME=$(echo "$container" | jq -r '.Names[0]' | sed 's/^\///')

echo "Fetching logs for: $CONTAINER_NAME"
echo "Container ID: ${CONTAINER_ID:0:12}"
echo "---"

# Build query parameters
params="stdout=true&stderr=true&tail=${TAIL_LINES}"
if [[ "$TIMESTAMPS" == "true" ]]; then
    params="${params}&timestamps=true"
fi
if [[ "$FOLLOW" == "true" ]]; then
    params="${params}&follow=true"
fi

# Get logs
# Note: Docker API returns raw log stream, not JSON
if [[ "$FOLLOW" == "true" ]]; then
    # Stream logs
    curl -s -N \
        -H "X-API-Key: ${PORTAINER_API_KEY}" \
        "${PORTAINER_URL}/api/endpoints/${ENDPOINT_ID}/docker/containers/${CONTAINER_ID}/logs?${params}" | \
        # Docker log format has 8-byte header per line, strip it
        while IFS= read -r line; do
            # Remove docker stream header (first 8 bytes per chunk)
            echo "$line" | cut -c9-
        done
else
    # Get logs (non-streaming)
    curl -s \
        -H "X-API-Key: ${PORTAINER_API_KEY}" \
        "${PORTAINER_URL}/api/endpoints/${ENDPOINT_ID}/docker/containers/${CONTAINER_ID}/logs?${params}" | \
        # Docker log format has 8-byte header per line, attempt to strip it
        sed 's/^.\{8\}//' 2>/dev/null || cat
fi