#!/bin/bash
# Common utility functions and variables for torrent-mover

# Global Runtime Variables
DRY_RUN=0
INTERACTIVE=0
CACHE_WARMUP=0
DEBUG=0

# To avoid reprocessing the same source directory (across different torrents)
declare -A processed_source_dirs

declare -A CHECKED_MOUNTS=()
declare -A PATH_CACHE

# Logging Functions
# All log messages go to stderr.
log_debug() {
    if [[ "${DEBUG}" -eq 1 ]]; then
        echo -e "[DEBUG] $(date '+%F %T') - $*" | tee -a "${LOG_FILE}" >&2
        [[ "${USE_SYSLOG}" == "true" ]] && logger -t torrent-mover "[DEBUG] $*"
    fi
}

log_info() {
    echo -e "[INFO] $(date '+%F %T') - $*" | tee -a "${LOG_FILE}" >&2
    [[ "${USE_SYSLOG}" == "true" ]] && logger -t torrent-mover "[INFO] $*"
}

log_warn() {
    echo -e "[WARN] $(date '+%F %T') - $*" | tee -a "${LOG_FILE}" >&2
    [[ "${USE_SYSLOG}" == "true" ]] && logger -t torrent-mover "[WARN] $*"
}

log_error() {
    echo -e "[ERROR] $(date '+%F %T') - $*" | tee -a "${LOG_FILE}" >&2
    [[ "${USE_SYSLOG}" == "true" ]] && logger -t torrent-mover "[ERROR] $*"
}

# Error Handling & Notifications
error_handler() {
    local lineno="$1"
    local msg="$2"
    log_error "Error on line ${lineno}: ${msg}"
    # Optionally send a notification (e.g., email)
    return 1
}

# translate_source: Converts the Transmission‑reported path into the local path.
translate_source() {
    local src="$1"
    echo "${src/#${TRANSMISSION_PATH_PREFIX}/${LOCAL_PATH_PREFIX}}"
}

# parse_args: Processes command‑line options.
parse_args() {
    while [[ $# -gt 0 ]]; do
        case "$1" in
            --dry-run) DRY_RUN=1; shift ;;
            --interactive) INTERACTIVE=1; shift ;;
            --cache-warmup) CACHE_WARMUP=1; shift ;;
            --debug) DEBUG=1; shift ;;
            --help)
                echo "Usage: $0 [--dry-run] [--interactive] [--cache-warmup] [--debug]" >&2
                exit 0
                ;;
            *) echo "Invalid option: $1" >&2; exit 1 ;;
        esac
    done
}

# check_dependencies: Ensures required commands are available.
check_dependencies() {
    local deps=("transmission-remote" "unzip" "7z" "parallel" "bc")
    for dep in "${deps[@]}"; do
        command -v "${dep}" >/dev/null 2>&1 || { log_error "Missing dependency: ${dep}"; exit 1; }
    done
    
    # Check for unrar or unrar-free
    if command -v unrar &>/dev/null; then
        log_debug "Found unrar command"
    elif command -v unrar-free &>/dev/null; then
        log_debug "Found unrar-free command"
        # Create an alias for unrar to point to unrar-free
        alias unrar="unrar-free"
    else
        log_error "Missing dependency: unrar or unrar-free"
        exit 1
    fi
}

# check_disk_usage: Warn if disk usage is over 90%.
check_disk_usage() {
    local dir="$1"
    [[ -z "${dir}" ]] && return
    if ! df -P "${dir}" &>/dev/null; then
        log_warn "Directory not found: ${dir}"
        return
    fi
    local mount_point
    mount_point=$(df -P "${dir}" | awk 'NR==2 {print $6}')
    [[ -z "${mount_point}" ]] && return
    if [[ -z "${CHECKED_MOUNTS["${mount_point}"]+x}" ]]; then
        local usage
        usage=$(df -P "${dir}" | awk 'NR==2 {sub(/%/, "", $5); print $5}')
        if (( usage >= 90 )); then
            log_warn "Storage warning: ${mount_point} at ${usage}% capacity"
        fi
        CHECKED_MOUNTS["${mount_point}"]=1
    fi
}

# run_command_safely: Safer version of command execution that prevents injection
run_command_safely() {
    # Instead of using eval with a command string, this function accepts the command and arguments separately
    # This prevents command injection vulnerabilities
    if [[ $# -eq 0 ]]; then
        log_error "No command provided to run_command_safely"
        return 1
    fi
    
    log_debug "Running command: $*"
    "$@"
    return $?
}

# retry_command: Execute a command with retries
retry_command() {
    local cmd="$1"
    local max_attempts="${2:-3}"  # Default to 3 attempts
    local wait_time="${3:-10}"    # Default to 10 seconds wait between attempts
    local attempt=1
    local exit_code=0
    local error_output=""
    
    # Create a temporary file for capturing error output
    local error_file
    error_file=$(mktemp)
    
    while (( attempt <= max_attempts )); do
        log_debug "Attempt $attempt of $max_attempts: $cmd"
        
        # Execute command and capture both exit code and stderr
        error_output=$( { eval "$cmd"; exit_code=$?; } 2>&1 > >(tee /dev/stderr) )
        
        if [[ ${exit_code} -eq 0 ]]; then
            log_debug "Command succeeded on attempt $attempt"
            rm -f "${error_file}"
            return 0
        else
            # Log detailed error information
            echo "${error_output}" > "${error_file}"
            log_warn "Command failed (attempt $attempt, exit code: ${exit_code})"
            log_debug "Error details: $(head -n 5 "${error_file}")"
            
            if (( attempt == max_attempts )); then
                log_error "Maximum attempts reached for command, last exit code: ${exit_code}"
                log_error "Last error output: $(head -n 10 "${error_file}")"
                rm -f "${error_file}"
                return ${exit_code}
            fi
            
            # Exponential backoff - wait longer for each successive attempt
            local adjusted_wait=$((wait_time * attempt))
            log_debug "Waiting ${adjusted_wait} seconds before retry"
            sleep ${adjusted_wait}
            (( attempt++ ))
        fi
    done
    
    rm -f "${error_file}"
    return 1
}

# run_in_transaction: Runs commands with an atomic operation guarantee
# If any command fails, attempts to roll back changes
run_in_transaction() {
    local action_desc="$1"
    local cleanup_cmd="$2"
    local main_cmd="$3"
    
    log_debug "Starting transaction: ${action_desc}"
    
    # Create marker file to indicate transaction in progress
    local transaction_id
    transaction_id=$(date +%s)-$$
    local transaction_marker="/tmp/torrent-mover-transaction-${transaction_id}"
    echo "${action_desc}" > "${transaction_marker}"
    
    # Execute the main command
    if ! eval "${main_cmd}"; then
        log_error "Transaction failed: ${action_desc}"
        
        # Only run cleanup if it exists
        if [[ -n "${cleanup_cmd}" ]]; then
            log_info "Attempting transaction rollback"
            if ! eval "${cleanup_cmd}"; then
                log_error "Rollback failed, manual intervention may be required"
            else
                log_info "Rollback completed successfully"
            fi
        fi
        
        # Clean up marker
        rm -f "${transaction_marker}"
        return 1
    fi
    
    # Clean up marker on success
    rm -f "${transaction_marker}"
    log_debug "Transaction completed successfully: ${action_desc}"
    return 0
}

# validate_directories: Ensure required directories exist and are writable
validate_directories() {
    local directories=("$@")
    for dir in "${directories[@]}"; do
        if [[ ! -d "${dir}" ]]; then
            log_error "Directory missing: ${dir}"
            return 1
        fi
        if [[ ! -w "${dir}" ]]; then
            log_error "Write permission denied: ${dir}"
            return 1
        fi
    done
    return 0
}