#!/bin/bash

# Generate OAuth2 access token for MCP agents
# Usage: ./generate-agent-token.sh [agent-name] [--client-id ID] [--client-secret SECRET] [--keycloak-url URL] [--realm REALM]

set -e

# Default values
AGENT_NAME="mcp-gateway-m2m"
CLIENT_ID=""
CLIENT_SECRET=""
KEYCLOAK_URL=""
KEYCLOAK_REALM="mcp-gateway"
OAUTH_TOKENS_DIR="../../.oauth-tokens"
VERBOSE=false

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m' # No Color

usage() {
    echo "Usage: $0 [agent-name] [options]"
    echo ""
    echo "Generate OAuth2 access token for MCP agents"
    echo ""
    echo "Arguments:"
    echo "  agent-name                Agent name (default: mcp-gateway-m2m)"
    echo ""
    echo "Options:"
    echo "  --client-id ID           OAuth2 client ID"
    echo "  --client-secret SECRET   OAuth2 client secret"
    echo "  --keycloak-url URL       Keycloak server URL"
    echo "  --realm REALM            Keycloak realm (default: mcp-gateway)"
    echo "  --oauth-dir DIR          OAuth tokens directory (default: ../../.oauth-tokens)"
    echo "  --verbose, -v            Verbose output"
    echo "  --help, -h               Show this help"
    echo ""
    echo "Examples:"
    echo "  # Use default agent (mcp-gateway-m2m) with config from .oauth-tokens/mcp-gateway-m2m.json"
    echo "  $0"
    echo ""
    echo "  # Use specific agent with config from .oauth-tokens/my-agent.json"
    echo "  $0 my-agent"
    echo ""
    echo "  # Override specific parameters"
    echo "  $0 my-agent --client-id custom-client --keycloak-url http://localhost:8080"
    echo ""
    echo "  # Specify all parameters manually"
    echo "  $0 test-agent --client-id test-client --client-secret secret123 --keycloak-url http://localhost:8080"
}

log() {
    if [ "$VERBOSE" = true ]; then
        echo -e "${BLUE}[INFO]${NC} $1"
    fi
}

error() {
    echo -e "${RED}[ERROR]${NC} $1" >&2
}

success() {
    echo -e "${GREEN}[SUCCESS]${NC} $1"
}

warning() {
    echo -e "${YELLOW}[WARNING]${NC} $1"
}

# Parse command line arguments
while [[ $# -gt 0 ]]; do
    case $1 in
        --client-id)
            CLIENT_ID="$2"
            shift 2
            ;;
        --client-secret)
            CLIENT_SECRET="$2"
            shift 2
            ;;
        --keycloak-url)
            KEYCLOAK_URL="$2"
            shift 2
            ;;
        --realm)
            KEYCLOAK_REALM="$2"
            shift 2
            ;;
        --oauth-dir)
            OAUTH_TOKENS_DIR="$2"
            shift 2
            ;;
        --verbose|-v)
            VERBOSE=true
            shift
            ;;
        --help|-h)
            usage
            exit 0
            ;;
        -*)
            error "Unknown option: $1"
            usage
            exit 1
            ;;
        *)
            # First positional argument is agent name
            if [ -z "$AGENT_NAME" ] || [ "$AGENT_NAME" = "mcp-gateway-m2m" ]; then
                AGENT_NAME="$1"
            else
                error "Unexpected argument: $1"
                usage
                exit 1
            fi
            shift
            ;;
    esac
done

log "Using agent name: $AGENT_NAME"
log "OAuth tokens directory: $OAUTH_TOKENS_DIR"

# Function to load config from JSON file
load_config_from_json() {
    local config_file="$OAUTH_TOKENS_DIR/${AGENT_NAME}.json"

    if [ ! -f "$config_file" ]; then
        error "Config file not found: $config_file"
        return 1
    fi

    log "Loading config from: $config_file"

    # Check if jq is available
    if ! command -v jq &> /dev/null; then
        error "jq is required to parse JSON config files. Please install jq."
        return 1
    fi

    # Extract values from JSON if not already provided
    if [ -z "$CLIENT_ID" ]; then
        CLIENT_ID=$(jq -r '.client_id // empty' "$config_file")
        log "Loaded CLIENT_ID from config: $CLIENT_ID"
    fi

    if [ -z "$CLIENT_SECRET" ]; then
        CLIENT_SECRET=$(jq -r '.client_secret // empty' "$config_file")
        log "Loaded CLIENT_SECRET from config: ${CLIENT_SECRET:0:10}..."
    fi

    if [ -z "$KEYCLOAK_URL" ]; then
        KEYCLOAK_URL=$(jq -r '.keycloak_url // .gateway_url // empty' "$config_file" | sed 's|/realms/.*||')
        log "Loaded KEYCLOAK_URL from config: $KEYCLOAK_URL"
    fi

    # Also try to get realm from config
    local config_realm=$(jq -r '.keycloak_realm // .realm // empty' "$config_file")
    if [ -n "$config_realm" ] && [ "$KEYCLOAK_REALM" = "mcp-gateway" ]; then
        KEYCLOAK_REALM="$config_realm"
        log "Loaded KEYCLOAK_REALM from config: $KEYCLOAK_REALM"
    fi
}

# Load config from JSON if available
if [ -z "$CLIENT_ID" ] || [ -z "$CLIENT_SECRET" ] || [ -z "$KEYCLOAK_URL" ]; then
    load_config_from_json
fi

# Validate required parameters
if [ -z "$CLIENT_ID" ]; then
    error "CLIENT_ID is required. Provide via --client-id or in config file."
    exit 1
fi

if [ -z "$CLIENT_SECRET" ]; then
    error "CLIENT_SECRET is required. Provide via --client-secret or in config file."
    exit 1
fi

if [ -z "$KEYCLOAK_URL" ]; then
    error "KEYCLOAK_URL is required. Provide via --keycloak-url or in config file."
    exit 1
fi

# Construct token URL
TOKEN_URL="$KEYCLOAK_URL/realms/$KEYCLOAK_REALM/protocol/openid-connect/token"

log "Token URL: $TOKEN_URL"
log "Client ID: $CLIENT_ID"
log "Realm: $KEYCLOAK_REALM"

# Make token request
echo "Requesting access token for agent: $AGENT_NAME"

response=$(curl -s -X POST "$TOKEN_URL" \
    -H "Content-Type: application/x-www-form-urlencoded" \
    -d "grant_type=client_credentials" \
    -d "client_id=$CLIENT_ID" \
    -d "client_secret=$CLIENT_SECRET" \
    -d "scope=openid email profile")

# Check if curl succeeded
if [ $? -ne 0 ]; then
    error "Failed to make token request to Keycloak"
    exit 1
fi

# Parse response
if command -v jq &> /dev/null; then
    # Check for error in response
    error_description=$(echo "$response" | jq -r '.error_description // empty')
    if [ -n "$error_description" ]; then
        error "Token request failed: $error_description"
        exit 1
    fi

    # Extract access token
    access_token=$(echo "$response" | jq -r '.access_token // empty')
    expires_in=$(echo "$response" | jq -r '.expires_in // empty')

    if [ -z "$access_token" ]; then
        error "No access token in response"
        echo "Response: $response"
        exit 1
    fi

    success "Access token generated successfully!"
    echo ""
    echo "Access Token: $access_token"
    echo ""

    if [ -n "$expires_in" ]; then
        echo "Expires in: $expires_in seconds"
        expiry_time=$(date -d "+$expires_in seconds" 2>/dev/null || date -r $(($(date +%s) + expires_in)) 2>/dev/null || echo "Unknown")
        echo "Expires at: $expiry_time"
        echo ""
    fi

    # Offer to save as environment file
    env_file="$OAUTH_TOKENS_DIR/${AGENT_NAME}.env"
    echo "Environment variables:"
    echo "export ACCESS_TOKEN=\"$access_token\""
    echo "export CLIENT_ID=\"$CLIENT_ID\""
    echo "export CLIENT_SECRET=\"$CLIENT_SECRET\""
    echo "export KEYCLOAK_URL=\"$KEYCLOAK_URL\""
    echo "export KEYCLOAK_REALM=\"$KEYCLOAK_REALM\""
    echo ""

    # Save to .env file
    mkdir -p "$OAUTH_TOKENS_DIR"
    cat > "$env_file" << EOF
# Generated access token for $AGENT_NAME
# Generated at: $(date)
export ACCESS_TOKEN="$access_token"
export CLIENT_ID="$CLIENT_ID"
export CLIENT_SECRET="$CLIENT_SECRET"
export KEYCLOAK_URL="$KEYCLOAK_URL"
export KEYCLOAK_REALM="$KEYCLOAK_REALM"
export AUTH_PROVIDER="keycloak"
EOF

    # Save to JSON file with metadata
    json_file="$OAUTH_TOKENS_DIR/${AGENT_NAME}-token.json"
    generated_at=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
    expires_at=""
    if [ -n "$expires_in" ]; then
        expires_at=$(date -u -d "+$expires_in seconds" +"%Y-%m-%dT%H:%M:%SZ" 2>/dev/null || date -u -r $(($(date +%s) + expires_in)) +"%Y-%m-%dT%H:%M:%SZ" 2>/dev/null || echo "")
    fi

    cat > "$json_file" << EOF
{
  "agent_name": "$AGENT_NAME",
  "access_token": "$access_token",
  "token_type": "Bearer",
  "expires_in": ${expires_in:-null},
  "generated_at": "$generated_at",
  "expires_at": ${expires_at:+"\"$expires_at\""},
  "provider": "keycloak",
  "keycloak_url": "$KEYCLOAK_URL",
  "keycloak_realm": "$KEYCLOAK_REALM",
  "client_id": "$CLIENT_ID",
  "scope": "openid email profile",
  "metadata": {
    "generated_by": "generate-agent-token.sh",
    "script_version": "1.0",
    "token_format": "JWT",
    "auth_method": "client_credentials"
  }
}
EOF

    success "Token saved to: $env_file"
    success "Token metadata saved to: $json_file"
    echo ""
    echo "To use this token, run:"
    echo "source $env_file"
    echo ""
    echo "Token JSON contains full metadata including expiration times."

else
    warning "jq not available, showing raw response:"
    echo "$response"
fi