#!/usr/bin/env bash
# learner-add.sh - Add a new learner account for maubot plugin development
# Usage: learner-add.sh <username> <ssh-pubkey>
#
# Creates:
# - Unix user account with SSH key
# - ~/plugins directory with hello-world starter plugin
# - Symlink in maubot plugins directory
# - Outputs onboarding instructions

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
MAUBOT_PLUGINS_DIR="/var/lib/maubot/plugins"
TEMPLATE_DIR="${SCRIPT_DIR}/../templates/plugin-skeleton"

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

log_info() { echo -e "${GREEN}[INFO]${NC} $1"; }
log_warn() { echo -e "${YELLOW}[WARN]${NC} $1"; }
log_error() { echo -e "${RED}[ERROR]${NC} $1" >&2; }

usage() {
    echo "Usage: $0 <username> <ssh-pubkey>"
    echo ""
    echo "Arguments:"
    echo "  username    - Learner's username (alphanumeric, 3-16 chars)"
    echo "  ssh-pubkey  - SSH public key (starts with ssh-ed25519, ssh-rsa, etc.)"
    echo ""
    echo "Example:"
    echo "  $0 alice 'ssh-ed25519 AAAA... alice@laptop'"
    exit 1
}

validate_username() {
    local username="$1"
    if [[ ! "$username" =~ ^[a-z][a-z0-9_-]{2,15}$ ]]; then
        log_error "Invalid username: must be 3-16 chars, start with letter, alphanumeric/underscore/dash only"
        exit 1
    fi

    # Check if user already exists
    if id "$username" &>/dev/null; then
        log_error "User '$username' already exists"
        exit 1
    fi
}

validate_ssh_key() {
    local key="$1"
    if [[ ! "$key" =~ ^ssh-(ed25519|rsa|ecdsa) ]]; then
        log_error "Invalid SSH key: must start with ssh-ed25519, ssh-rsa, or ssh-ecdsa"
        exit 1
    fi
}

create_user() {
    local username="$1"
    local ssh_key="$2"

    log_info "Creating user '$username'..."

    # Create user with home directory
    # NixOS: don't specify shell (uses default), group is 'users'
    useradd -m -g users "$username"

    # Add to learners group for Slack token access
    usermod -aG learners "$username"

    # Set up SSH key
    local ssh_dir="/home/$username/.ssh"
    mkdir -p "$ssh_dir"
    echo "$ssh_key" > "$ssh_dir/authorized_keys"
    chmod 700 "$ssh_dir"
    chmod 600 "$ssh_dir/authorized_keys"
    chown -R "$username:users" "$ssh_dir"

    # Add Slack env vars to bashrc
    echo '' >> "/home/$username/.bashrc"
    echo '# Slack bot development tokens' >> "/home/$username/.bashrc"
    echo 'source /etc/slack-learner.env' >> "/home/$username/.bashrc"

    # Set up ~/.local/bin with claude symlink
    local local_bin="/home/$username/.local/bin"
    mkdir -p "$local_bin"
    ln -sf /usr/local/bin/claude "$local_bin/claude"
    chown -R "$username:users" "/home/$username/.local"

    log_info "User created with SSH access"
}

setup_plugin_directory() {
    local username="$1"
    local plugin_name="hello-${username}"
    local user_plugins_dir="/home/$username/plugins"
    local plugin_dir="$user_plugins_dir/$plugin_name"

    log_info "Setting up plugin directory..."

    # Create plugins directory
    mkdir -p "$plugin_dir"
    mkdir -p "$plugin_dir/dist"

    # Python module names must use underscores, not hyphens
    local module_name="${plugin_name//-/_}"

    # Copy template if exists, otherwise create from scratch
    if [[ -d "$TEMPLATE_DIR" ]]; then
        cp -r "$TEMPLATE_DIR/"* "$plugin_dir/"
        # Rename MODULE_NAME directory to actual module name
        if [[ -d "$plugin_dir/MODULE_NAME" ]]; then
            mv "$plugin_dir/MODULE_NAME" "$plugin_dir/$module_name"
        fi
        # Replace placeholders in all files
        find "$plugin_dir" -type f -exec sed -i "s/MODULE_NAME/$module_name/g" {} \;
        find "$plugin_dir" -type f -exec sed -i "s/USERNAME/$username/g" {} \;
    else
        # Create minimal starter plugin
        create_starter_plugin "$plugin_dir" "$module_name" "$username"
    fi

    # Set ownership
    chown -R "$username:users" "$user_plugins_dir"

    # Make plugin dir readable by maubot group
    chmod 755 "/home/$username"
    chmod 755 "$user_plugins_dir"
    chmod -R 755 "$plugin_dir"

    log_info "Plugin directory created at $plugin_dir"
}

create_starter_plugin() {
    local plugin_dir="$1"
    local module_name="$2"
    local username="$3"

    # Create module directory
    mkdir -p "$plugin_dir/$module_name"

    # maubot.yaml
    cat > "$plugin_dir/maubot.yaml" << EOF
maubot: 0.4.0
id: xyz.clarun.${module_name}
version: 0.1.0
license: MIT
modules:
  - ${module_name}
main_class: ${module_name}.Bot
EOF

    # Python module __init__.py
    cat > "$plugin_dir/$module_name/__init__.py" << EOF
from .bot import Bot

__all__ = ["Bot"]
EOF

    # Main bot.py
    cat > "$plugin_dir/$module_name/bot.py" << EOF
from maubot import Plugin, MessageEvent
from maubot.handlers import command


class Bot(Plugin):
    """Hello world bot for $username"""

    @command.new("hello")
    async def hello_command(self, evt: MessageEvent) -> None:
        """Respond to !hello command"""
        await evt.reply(f"Hello from ${username}'s bot!")

    @command.new("ping")
    async def ping_command(self, evt: MessageEvent) -> None:
        """Respond to !ping command"""
        await evt.reply("Pong!")
EOF

    # Makefile
    cat > "$plugin_dir/Makefile" << 'EOF'
PLUGIN_NAME := $(shell grep '^id:' maubot.yaml | cut -d: -f2 | tr -d ' ')
PLUGIN_VERSION := $(shell grep '^version:' maubot.yaml | cut -d: -f2 | tr -d ' ')
MBP_FILE := dist/$(PLUGIN_NAME)-$(PLUGIN_VERSION).mbp

.PHONY: build reload clean help

help:
	@echo "Available targets:"
	@echo "  build   - Build the .mbp plugin file"
	@echo "  reload  - Reload plugin in maubot (requires instance configured)"
	@echo "  clean   - Remove built files"
	@echo "  dev     - Build and reload"

build:
	@echo "Building $(PLUGIN_NAME)..."
	@mkdir -p dist
	@rm -f $(MBP_FILE)
	@zip -r $(MBP_FILE) maubot.yaml $(shell grep -E '^  - ' maubot.yaml | sed 's/  - //')
	@echo "Built: $(MBP_FILE)"

reload:
	@echo "Reloading plugin..."
	@echo "TODO: Add maubot API reload command"

clean:
	rm -rf dist/*.mbp

dev: build reload
EOF

    # README
    cat > "$plugin_dir/README.md" << EOF
# $module_name

Hello world maubot plugin for $username.

## Quick Start

1. Edit \`$module_name/bot.py\` to add your bot logic
2. Run \`make build\` to create the .mbp file
3. Upload to maubot via admin UI (http://localhost:29316)

## Commands

- \`!hello\` - Says hello
- \`!ping\` - Responds with pong

## Files

- \`maubot.yaml\` - Plugin manifest
- \`$module_name/bot.py\` - Main bot code
- \`Makefile\` - Build commands
EOF
}

create_maubot_symlink() {
    local username="$1"
    local plugin_name="hello-${username}"
    local plugin_dir="/home/$username/plugins/$plugin_name"
    local symlink_path="$MAUBOT_PLUGINS_DIR/${username}-${plugin_name}.mbp"

    log_info "Creating maubot plugin symlink..."

    # Note: Symlink will point to the built .mbp file
    # For now, we'll link to the dist directory's expected output
    # The learner will need to run 'make build' first

    # We could also configure maubot to load from source directories
    # but .mbp symlinks are simpler for now

    log_warn "Learner must run 'make build' before plugin appears in maubot"
}

print_onboarding() {
    local username="$1"
    local server_ip
    # NixOS: use ip command instead of hostname -I
    server_ip=$(ip -4 addr show scope global | grep -oP '(?<=inet\s)\d+(\.\d+){3}' | head -1)

    echo ""
    echo "=========================================="
    echo "  Dev Environment Ready: $username"
    echo "=========================================="
    echo ""
    echo "## SSH Config (~/.ssh/config on your laptop)"
    echo ""
    echo "   Host dev-server"
    echo "       HostName ${server_ip:-<server-ip>}"
    echo "       User $username"
    echo "       LocalForward 8080 127.0.0.1:8080"
    echo ""
    echo "## Quick Start"
    echo ""
    echo "1. SSH in:"
    echo "   ssh dev-server"
    echo ""
    echo "2. Authenticate Claude (first time only):"
    echo "   claude"
    echo "   # Opens localhost URL - paste in your local browser"
    echo "   # Complete OAuth, token flows back automatically"
    echo ""
    echo "3. Start coding:"
    echo "   mkdir mybot && cd mybot"
    echo "   claude 'create a slack bot that responds to hello'"
    echo ""
    echo "## Tools Available"
    echo "   python3, uv, go (nix profile install nixpkgs#go)"
    echo "   Slack tokens: \$SLACK_BOT_TOKEN, \$SLACK_APP_TOKEN"
    echo ""
    echo "=========================================="
}

main() {
    if [[ $# -lt 2 ]]; then
        usage
    fi

    local username="$1"
    local ssh_key="$2"

    # Must run as root
    if [[ $EUID -ne 0 ]]; then
        log_error "This script must be run as root"
        exit 1
    fi

    validate_username "$username"
    validate_ssh_key "$ssh_key"

    create_user "$username" "$ssh_key"
    setup_plugin_directory "$username"
    create_maubot_symlink "$username"
    print_onboarding "$username"

    log_info "Learner '$username' setup complete!"
}

main "$@"