#!/bin/bash

# Exit immediately on error
set -e

# Configuration
backupPath='/mnt/backups'
password_file="/etc/restic-password"
LOG_FILE="/var/log/restic_snapshot.log"

# Logging function
log_message() {
    echo "[$(date +'%Y-%m-%d %H:%M:%S')] $1" | tee -a "$LOG_FILE"
}

# Function: Display usage
display_usage() {
    echo "Usage: $0 <tag>"
    echo "Available tags:"
    restic -r "$RESTIC_REPOSITORY" snapshots --json 2>/dev/null | jq -r '.[].tags[]' | sort -u || echo "main_backup, wordpress_db, core_files, media_themes, full_backup"
    exit 1
}

# Ensure dependencies are installed
validate_dependencies() {
    for cmd in restic jq; do
        if ! command -v "$cmd" &>/dev/null; then
            log_message "ERROR: Required command '$cmd' not found. Please install it."
            exit 1
        fi
    done
}

# Validate environment
validate_environment() {
    if [ ! -f "$password_file" ]; then
        log_message "ERROR: Password file not found at $password_file"
        exit 1
    fi

    if [ ! -d "$backupPath" ]; then
        log_message "ERROR: Backup path '$backupPath' does not exist or is not accessible."
        exit 1
    fi
}

# Main script logic
main() {
    # Ensure a tag is provided
    if [ "$#" -ne 1 ]; then
        display_usage
    fi

    # Assign input argument
    TAG=$1

    # Set Restic environment variables
    export RESTIC_REPOSITORY="$backupPath"
    export RESTIC_PASSWORD=$(cat "$password_file")

    # Validate the tag
    if ! restic -r "$RESTIC_REPOSITORY" snapshots --json 2>/dev/null | jq -e ".[] | select(.tags[] == \"$TAG\")" &>/dev/null; then
        log_message "ERROR: Unknown or unused tag '$TAG'."
        display_usage
    fi

    # Display snapshots for the provided tag
    log_message "Retrieving snapshots for tag '$TAG'..."
    if restic -r "$RESTIC_REPOSITORY" snapshots --tag "$TAG" --json | jq -r '.[] | "\(.short_id) \(.time) \(.tags | join(", "))"' 2>/dev/null; then
        log_message "Snapshots for tag '$TAG' displayed successfully."
    else
        log_message "ERROR: Unable to display snapshots for tag '$TAG'."
        exit 1
    fi
}

# Run validations and execute the main function
validate_dependencies
validate_environment
main "$@"