#!/bin/bash

set -e

# Restic Backup Utility Script
# Provides independent backup functionality, can be called by other scripts

# Logging functions
log() {
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] [BACKUP] $*"
}

log_success() {
    echo -e "\033[32m[$(date '+%Y-%m-%d %H:%M:%S')] [SUCCESS] $*\033[0m"
}

log_error() {
    echo -e "\033[31m[$(date '+%Y-%m-%d %H:%M:%S')] [ERROR] $*\033[0m"
}

log_warn() {
    echo -e "\033[33m[$(date '+%Y-%m-%d %H:%M:%S')] [WARN] $*\033[0m"
}

# Display usage instructions
show_usage() {
    cat << EOF
Usage: $0 [options] [paths...]

Options:
  -c, --config FILE     Specify configuration file path
  -r, --repository DIR  Specify repository path (overrides config file)
  -p, --password PASS   Specify password (overrides config file)
  -t, --tag TAG         Add backup tag (can be used multiple times)
  -e, --exclude PATTERN Add exclude pattern (can be used multiple times)
  --compression MODE    Compression mode: off, fastest, auto, better, max (default: auto)
  -v, --verbose         Enable verbose output
  -n, --dry-run         Only show operations to be executed
  -h, --help            Show this help message

Compression mode explanation:
  off     - No compression (fastest backup speed)
  fastest - Fastest compression (minimal CPU usage)
  auto    - Auto compression (default, balanced speed and compression ratio)
  better  - Better compression (more CPU, better compression ratio)
  max     - Maximum compression (highest CPU, best compression ratio)

Examples:
  $0                              # Backup using default configuration
  $0 /home/user/data              # Backup specified path
  $0 -t "manual" -v /important    # Verbose backup with tag
  $0 --compression max -v         # Verbose backup with maximum compression
  $0 -c custom.conf -n            # Dry run with custom configuration

EOF
}

# Load configuration file
load_config() {
    local config_file="$1"
    
    if [[ -f "$config_file" ]]; then
        log "Loading configuration file: $config_file"
        
        # Use safe configuration loading method
        local temp_config="/tmp/restic_backup_config_$$"
        sed 's/^\([^#]*\)=\(.*\)$/\1=${\1:-\2}/' "$config_file" > "$temp_config"
        source "$temp_config"
        rm -f "$temp_config"
        
        log_success "Configuration loaded (environment variables take precedence)"
    else
        log_warn "Configuration file does not exist: $config_file"
    fi
}

# Set environment variables
setup_environment() {
    # Check necessary configuration variables
    if [[ -z "$RESTIC_REPOSITORY_PATH" ]]; then
        log_error "RESTIC_REPOSITORY_PATH not set, please check configuration file or environment variables"
        return 1
    fi
    
    # Check password setting
    if [[ -z "${RESTIC_PASSWORD:-}" ]]; then
        log_error "RESTIC_PASSWORD not set, please check configuration file or environment variables"
        return 1
    fi
    
    log "Using password from environment variables"
    
    # Export environment variables
    export RESTIC_REPOSITORY="$RESTIC_REPOSITORY_PATH"
    export RESTIC_PASSWORD
    export RESTIC_CACHE_DIR
    
    # Set performance tuning environment variables (read from config file or environment variables)
    [[ -n "$RESTIC_MAX_PROCS" ]] && export GOMAXPROCS="$RESTIC_MAX_PROCS"
    [[ -n "$RESTIC_TEMP_DIR" ]] && export TMPDIR="$RESTIC_TEMP_DIR"
    [[ -n "$RESTIC_FEATURES" ]] && export RESTIC_FEATURES
    
    # Check restic command
    if ! command -v restic &> /dev/null; then
        log_error "restic command not found"
        return 1
    fi
    
    log_success "Environment setup completed"
}

# Validate backup paths
validate_paths() {
    local paths=("$@")
    local valid_paths=()
    
    for path in "${paths[@]}"; do
        if [[ -e "$path" ]]; then
            valid_paths+=("$path")
            log "Valid path: $path"
        else
            log_warn "Path does not exist: $path"
        fi
    done
    
    if [[ ${#valid_paths[@]} -eq 0 ]]; then
        log_error "No valid backup paths"
        return 1
    fi
    
    # Store valid paths in global variable
    VALIDATED_PATHS=("${valid_paths[@]}")
    return 0
}

# Perform backup
perform_backup() {
    local dry_run="$1"
    shift
    local backup_paths=("$@")
    
    log "Starting backup operation..."
    
    # If no paths specified, use paths from configuration
    if [[ ${#backup_paths[@]} -eq 0 ]]; then
        IFS=':' read -ra backup_paths <<< "$RESTIC_BACKUP_PATHS"
    fi
    
    # Validate paths
    if ! validate_paths "${backup_paths[@]}"; then
        return 1
    fi
    
    # Build backup command arguments
    local args=("backup")
    
    # Add exclude patterns
    if [[ -n "$RESTIC_EXCLUDE_PATTERNS" ]]; then
        IFS=',' read -ra patterns <<< "$RESTIC_EXCLUDE_PATTERNS"
        for pattern in "${patterns[@]}"; do
            args+=("--exclude" "$pattern")
        done
    fi
    
    # Add extra exclude patterns (from command line)
    for exclude in "${EXTRA_EXCLUDES[@]}"; do
        args+=("--exclude" "$exclude")
    done
    
    # Add tags
    if [[ -n "$RESTIC_BACKUP_TAG" ]]; then
        IFS=',' read -ra tags <<< "$RESTIC_BACKUP_TAG"
        for tag in "${tags[@]}"; do
            args+=("--tag" "$tag")
        done
    fi
    
    # Add extra tags (from command line)
    for tag in "${EXTRA_TAGS[@]}"; do
        args+=("--tag" "$tag")
    done
    
    # Add options
    [[ "$RESTIC_VERBOSE" == "true" ]] && args+=("--verbose")
    
    # Add compression option
    args+=("--compression" "$RESTIC_COMPRESSION")
    
    # New: Performance tuning options (prioritize RESTIC_READ_CONCURRENCY, otherwise use RESTIC_PARALLEL_UPLOADS)
    if [[ -n "$RESTIC_READ_CONCURRENCY" ]]; then
        args+=("--read-concurrency" "$RESTIC_READ_CONCURRENCY")
    elif [[ -n "$RESTIC_PARALLEL_UPLOADS" ]]; then
        args+=("--read-concurrency" "$RESTIC_PARALLEL_UPLOADS")
    fi
    [[ -n "$RESTIC_PACK_SIZE" ]] && args+=("--pack-size" "$RESTIC_PACK_SIZE")
    [[ "$RESTIC_NO_SCAN" == "true" ]] && args+=("--no-scan")
    [[ "$RESTIC_EXTRA_VERIFY" == "false" ]] && args+=("--no-extra-verify")
    [[ "$RESTIC_NO_CACHE" == "true" ]] && args+=("--no-cache")
    
    # New: Backend connection configuration
    if [[ -n "$RESTIC_BACKEND_CONNECTIONS" ]]; then
        # Auto-detect backend type
        if [[ "$RESTIC_REPOSITORY_PATH" =~ ^s3: ]]; then
            args+=("-o" "s3.connections=$RESTIC_BACKEND_CONNECTIONS")
        elif [[ "$RESTIC_REPOSITORY_PATH" =~ ^rest: ]]; then
            args+=("-o" "rest.connections=$RESTIC_BACKEND_CONNECTIONS")
        elif [[ "$RESTIC_REPOSITORY_PATH" =~ ^sftp: ]]; then
            args+=("-o" "sftp.connections=$RESTIC_BACKEND_CONNECTIONS")
        else
            # Local backend
            args+=("-o" "local.connections=$RESTIC_BACKEND_CONNECTIONS")
        fi
    fi
    
    # Add paths
    args+=("${VALIDATED_PATHS[@]}")
    
    log "Executing command: restic ${args[*]}"
    
    if [[ "$dry_run" == "true" ]]; then
        log_warn "Dry run mode - actual backup not executed"
        return 0
    fi
    
    # Execute backup
    if restic "${args[@]}"; then
        log_success "Backup completed successfully"
        return 0
    else
        log_error "Backup failed"
        return 1
    fi
}

# Main function
main() {
    # Parse command line arguments
    local config_file=""
    local dry_run="false"
    local backup_paths=()
    local EXTRA_TAGS=()
    local EXTRA_EXCLUDES=()
    
    while [[ $# -gt 0 ]]; do
        case $1 in
            -c|--config)
                config_file="$2"
                shift 2
                ;;
            -r|--repository)
                RESTIC_REPOSITORY_PATH="$2"
                shift 2
                ;;
            -p|--password)
                RESTIC_PASSWORD="$2"
                shift 2
                ;;
            -t|--tag)
                EXTRA_TAGS+=("$2")
                shift 2
                ;;
            -e|--exclude)
                EXTRA_EXCLUDES+=("$2")
                shift 2
                ;;
            --compression)
                RESTIC_COMPRESSION="$2"
                shift 2
                ;;
            -v|--verbose)
                RESTIC_VERBOSE="true"
                shift
                ;;
            -n|--dry-run)
                dry_run="true"
                shift
                ;;
            -h|--help)
                show_usage
                exit 0
                ;;
            -*)
                log_error "Unknown option: $1"
                show_usage
                exit 1
                ;;
            *)
                backup_paths+=("$1")
                shift
                ;;
        esac
    done
    
    log "======= Restic Backup Tool ======="
    
    # Load configuration file
    if [[ -n "$config_file" ]]; then
        load_config "$config_file"
    elif [[ -f "${HOME:-/home/user}/config/restic.conf" ]]; then
        load_config "${HOME:-/home/user}/config/restic.conf"
    fi
    
    # Setup environment
    if ! setup_environment; then
        exit 1
    fi
    
    # Display configuration information
    log "Backup configuration:"
    log "  Repository path: $RESTIC_REPOSITORY_PATH"
    log "  Cache directory: $RESTIC_CACHE_DIR"
    log "  Compression mode: $RESTIC_COMPRESSION"
    log "  Dry run mode: $dry_run"
    log "  Performance tuning:"
    log "    - Backend connections: ${RESTIC_BACKEND_CONNECTIONS:-default}"
    log "    - CPU core limit: ${RESTIC_MAX_PROCS:-all available}"
    log "    - Read concurrency: ${RESTIC_READ_CONCURRENCY:-default}"
    log "    - Pack size: ${RESTIC_PACK_SIZE:-16}MiB"
    log "    - Disable scan: ${RESTIC_NO_SCAN:-false}"
    log "    - Extra verify: ${RESTIC_EXTRA_VERIFY:-true}"
    log "    - Disable cache: ${RESTIC_NO_CACHE:-false}"
    [[ -n "$RESTIC_TEMP_DIR" ]] && log "    - Temp directory: $RESTIC_TEMP_DIR"
    [[ -n "$RESTIC_FEATURES" ]] && log "    - Feature flags: $RESTIC_FEATURES"
    [[ ${#EXTRA_TAGS[@]} -gt 0 ]] && log "  Extra tags: ${EXTRA_TAGS[*]}"
    [[ ${#EXTRA_EXCLUDES[@]} -gt 0 ]] && log "  Extra excludes: ${EXTRA_EXCLUDES[*]}"
    
    # Execute backup
    perform_backup "$dry_run" "${backup_paths[@]}"
}

# If script is executed directly (not sourced)
if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
    main "$@"
fi