#!/bin/bash
# ============================================================================
# Gitea Auto-Update Script
# ============================================================================
# Automatically updates low-risk containers (nginx, certbot) with backup,
# health checks, and automatic rollback on failure.
#
# Usage: ./auto-update.sh <container1> [container2] [...]
# Example: ./auto-update.sh nginx certbot
# ============================================================================

set -e

# ============================================================================
# Configuration
# ============================================================================
readonly SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
readonly DOCKER_COMPOSE_DIR="/opt/gitea"
readonly COMPOSE_FILE="${DOCKER_COMPOSE_DIR}/docker-compose.yml"
readonly BACKUP_SCRIPT="${SCRIPT_DIR}/backup.sh"
readonly HEALTH_CHECK_SCRIPT="${SCRIPT_DIR}/health-check.sh"
readonly LOG_FILE="/var/log/gitea-auto-update.log"
readonly ROLLBACK_INFO="/tmp/gitea-rollback-info-$$.json"

# Wait timeouts (seconds)
readonly CONTAINER_STARTUP_WAIT=10

# Output colors
readonly GREEN='\033[0;32m'
readonly YELLOW='\033[1;33m'
readonly RED='\033[0;31m'
readonly NC='\033[0m'

# ============================================================================
# Logging Functions
# ============================================================================
get_timestamp() {
    date '+%Y-%m-%d %H:%M:%S'
}

log_info() {
    local message="[$(get_timestamp)] [INFO] $1"
    echo -e "${YELLOW}${message}${NC}"
    echo "${message}" >> "${LOG_FILE}"
}

log_success() {
    local message="[$(get_timestamp)] [SUCCESS] $1"
    echo -e "${GREEN}${message}${NC}"
    echo "${message}" >> "${LOG_FILE}"
}

log_error() {
    local message="[$(get_timestamp)] [ERROR] $1"
    echo -e "${RED}${message}${NC}" >&2
    echo "${message}" >> "${LOG_FILE}"
}

error_exit() {
    log_error "$1"
    cleanup
    exit 1
}

# ============================================================================
# Cleanup Function
# ============================================================================
cleanup() {
    if [ -f "${ROLLBACK_INFO}" ]; then
        rm -f "${ROLLBACK_INFO}"
    fi
}

# ============================================================================
# Helper Functions
# ============================================================================
change_to_compose_dir() {
    cd "${DOCKER_COMPOSE_DIR}" || error_exit "Failed to change to ${DOCKER_COMPOSE_DIR}"
}

run_compose() {
    docker compose -f "${COMPOSE_FILE}" "$@"
}

# ============================================================================
# Validation Functions
# ============================================================================
validate_args() {
    if [ $# -eq 0 ]; then
        error_exit "No containers specified. Usage: $0 <container1> [container2] [...]"
    fi
    
    for container in "$@"; do
        if ! run_compose config --services | grep -q "^${container}$"; then
            error_exit "Container '${container}' not found in docker-compose.yml"
        fi
    done
    
    log_success "Container validation passed"
}

# ============================================================================
# Rollback Management Functions
# ============================================================================
save_current_images() {
    log_info "Saving current image versions for rollback..."
    
    echo "{" > "${ROLLBACK_INFO}"
    local first=true
    
    for container in "$@"; do
        local image=$(run_compose images -q "${container}" 2>/dev/null | head -n1)
        
        if [ -n "${image}" ]; then
            if [ "${first}" = true ]; then
                first=false
            else
                echo "," >> "${ROLLBACK_INFO}"
            fi
            echo "  \"${container}\": \"${image}\"" >> "${ROLLBACK_INFO}"
            log_info "Saved ${container}: ${image}"
        fi
    done
    
    echo "}" >> "${ROLLBACK_INFO}"
    log_success "Current image versions saved"
}

rollback() {
    log_error "Rolling back to previous versions..."
    
    if [ ! -f "${ROLLBACK_INFO}" ]; then
        log_error "No rollback information found"
        return 1
    fi
    
    change_to_compose_dir
    
    # Extract containers from rollback info and restore
    local containers=$(grep -o '"[^"]*":' "${ROLLBACK_INFO}" | tr -d '":' | tr '\n' ' ')
    
    for container in ${containers}; do
        log_info "Rolling back ${container}..."
        run_compose up -d "${container}" || log_error "Failed to rollback ${container}"
    done
    
    log_success "Rollback completed"
}

# ============================================================================
# Update Functions
# ============================================================================
run_backup() {
    log_info "Running backup before update..."
    
    if ! bash "${BACKUP_SCRIPT}"; then
        error_exit "Backup failed - aborting update"
    fi
    
    log_success "Backup completed successfully"
}

pull_new_images() {
    log_info "Pulling new images..."
    
    change_to_compose_dir
    
    for container in "$@"; do
        log_info "Pulling image for ${container}..."
        if ! run_compose pull "${container}"; then
            error_exit "Failed to pull image for ${container}"
        fi
    done
    
    log_success "All images pulled successfully"
}

recreate_containers() {
    log_info "Recreating containers..."
    
    change_to_compose_dir
    
    if ! run_compose up -d "$@"; then
        error_exit "Failed to recreate containers"
    fi
    
    # Wait for containers to start
    log_info "Waiting for containers to start..."
    sleep "${CONTAINER_STARTUP_WAIT}"
    
    log_success "Containers recreated successfully"
}

run_health_check() {
    log_info "Running health check..."
    
    if bash "${HEALTH_CHECK_SCRIPT}"; then
        log_success "Health check passed"
        return 0
    else
        log_error "Health check failed"
        return 1
    fi
}

send_failure_notification() {
    local subject="$1"
    local body="$2"
    
    # Placeholder for email notification
    # Will be configured with proper email settings in Task 6
    log_error "NOTIFICATION: ${subject}"
    log_error "${body}"
    
    # TODO: Implement actual email sending via mail command or SMTP
    # echo "${body}" | mail -s "${subject}" admin@example.com
}

# ============================================================================
# Main Execution
# ============================================================================
main() {
    log_info "=========================================="
    log_info "Gitea Auto-Update Started"
    log_info "Containers: $*"
    log_info "=========================================="
    
    # Validate input
    validate_args "$@"
    
    # Save current state for rollback
    save_current_images "$@"
    
    # Run backup
    run_backup
    
    # Pull new images
    pull_new_images "$@"
    
    # Recreate containers
    recreate_containers "$@"
    
    # Run health check
    if run_health_check; then
        log_success "=========================================="
        log_success "Update completed successfully"
        log_success "Updated containers: $*"
        log_success "=========================================="
        cleanup
        exit 0
    else
        log_error "Health check failed after update"
        rollback
        
        # Run health check again after rollback
        if run_health_check; then
            log_success "Rollback successful - services restored"
            send_failure_notification \
                "Gitea Update Failed - Rolled Back" \
                "Update of containers [$*] failed health check and was rolled back. Services are now healthy."
        else
            log_error "Critical: Services still unhealthy after rollback"
            send_failure_notification \
                "CRITICAL: Gitea Update Failed - Manual Intervention Required" \
                "Update of containers [$*] failed and rollback did not restore health. IMMEDIATE ATTENTION REQUIRED."
        fi
        
        cleanup
        exit 1
    fi
}

main "$@"