#!/bin/sh
# ssh_passwordless_manager.sh
# Manage passwordless SSH hosts: list, add, delete, edit, query.

CONFIG_FILE="$HOME/.ssh_playground_hosts"

# Ensure config file exists
touch "$CONFIG_FILE"

# Print usage information
usage() {
  cat <<EOF
Usage: $(basename "$0") <command> [options]

Commands:
  list                          List all hosts configured for SSH connection
  add <alias> <user@host> <priv_key> [pub_key]
                                Add a new host; installs public key and saves config
  delete <alias>                Remove a host; deletes key from remote and config
  edit <alias> <new_priv_key> [new_pub_key]
                                Replace the key for a given host
  query <alias>                 Show the configuration for a given host
  help                          Show this help message
EOF
  exit 1
}

# Load entry by alias
load_entry() {
  grep "^$1|" "$CONFIG_FILE"
}

# List hosts
list_hosts() {
  if [ ! -s "$CONFIG_FILE" ]; then
    echo "No hosts configured."
    exit 0
  fi
  printf "%-15s %-25s %s\n" "ALIAS" "USER@HOST" "PRIVATE_KEY"
  echo "---------------------------------------------------------------"
  while IFS='|' read -r alias userhost privkey pubkey; do
    printf "%-15s %-25s %s\n" "$alias" "$userhost" "$privkey"
  done < "$CONFIG_FILE"
}

# Add host
add_host() {
  [ $# -lt 3 ] && echo "add requires alias, user@host, private key" && usage
  alias="$1"; userhost="$2"; privkey="$3"; pubkey="$4"
  [ -z "$pubkey" ] && pubkey="${privkey}.pub"

  if load_entry "$alias" >/dev/null; then
    echo "Alias '$alias' already exists." && exit 1
  fi

  # Copy public key to remote
  echo "Installing public key to $userhost..."
  ssh-copy-id -i "$pubkey" "$userhost" || { echo "Failed to install key."; exit 1; }

  # Save to config
  echo "$alias|$userhost|$privkey|$pubkey" >> "$CONFIG_FILE"
  echo "Host '$alias' added."
}

# Delete host
delete_host() {
  [ $# -lt 1 ] && echo "delete requires alias" && usage
  alias="$1"
  entry=$(load_entry "$alias")
  [ -z "$entry" ] && echo "Alias '$alias' not found." && exit 1

  IFS='|' read -r _ userhost privkey pubkey <<EOF
$entry
EOF

  # Read public key content
  pubcontent=$(sed -n '1p' "$pubkey")

  # Remove key from remote authorized_keys
  echo "Removing public key from $userhost..."
  ssh "$userhost" "mkdir -p ~/.ssh && chmod 700 ~/.ssh && \
    grep -v '$pubcontent' ~/.ssh/authorized_keys > ~/.ssh/authorized_keys.tmp && \
    mv ~/.ssh/authorized_keys.tmp ~/.ssh/authorized_keys" || echo "Warning: could not remove key on remote."

  # Remove from config
  grep -v "^$alias|" "$CONFIG_FILE" > "$CONFIG_FILE.tmp" && mv "$CONFIG_FILE.tmp" "$CONFIG_FILE"
  echo "Host '$alias' deleted."
}

# Edit host key
edit_host() {
  [ $# -lt 2 ] && echo "edit requires alias and new private key" && usage
  alias="$1"; newpriv="$2"; newpub="$3"
  [ -z "$newpub" ] && newpub="${newpriv}.pub"
  entry=$(load_entry "$alias")
  [ -z "$entry" ] && echo "Alias '$alias' not found." && exit 1

  IFS='|' read -r _ userhost oldpriv oldpub <<EOF
$entry
EOF

  # Remove old key
  oldcontent=$(sed -n '1p' "$oldpub")
  echo "Removing old key from $userhost..."
  ssh "$userhost" "grep -v '$oldcontent' ~/.ssh/authorized_keys > ~/.ssh/authorized_keys.tmp && mv ~/.ssh/authorized_keys.tmp ~/.ssh/authorized_keys" || echo "Warning: could not remove old key."

  # Install new key
  echo "Installing new public key to $userhost..."
  ssh-copy-id -i "$newpub" "$userhost" || { echo "Failed to install new key."; exit 1; }

  # Update config
  grep -v "^$alias|" "$CONFIG_FILE" > "$CONFIG_FILE.tmp"
  echo "$alias|$userhost|$newpriv|$newpub" >> "$CONFIG_FILE.tmp"
  mv "$CONFIG_FILE.tmp" "$CONFIG_FILE"
  echo "Host '$alias' updated."
}

# Query host
query_host() {
  [ $# -lt 1 ] && echo "query requires alias" && usage
  alias="$1"
  entry=$(load_entry "$alias")
  [ -z "$entry" ] && echo "Alias '$alias' not found." && exit 1
  IFS='|' read -r _ userhost privkey pubkey <<EOF
$entry
EOF
  echo "Alias    : $alias"
  echo "Host     : $userhost"
  echo "Priv key : $privkey"
  echo "Pub key  : $pubkey"
}

# Main dispatch
case "$1" in
  list)   list_hosts ;; 
  add)    shift; add_host "$@" ;; 
  delete) shift; delete_host "$@" ;; 
  edit)   shift; edit_host "$@" ;; 
  query)  shift; query_host "$@" ;; 
  help|*) usage ;; 
 esac