package rpc

import (
	"bufio"
	"encoding/json"
	"fmt"
	"net"
	"os"
	"time"
)

// ClientVersion is the version of this RPC client
// This should match the bd CLI version for proper compatibility checks
// It's set dynamically by main.go from cmd/bd/version.go before making RPC calls
var ClientVersion = "0.0.0" // Placeholder; overridden at startup

// Client represents an RPC client that connects to the daemon
type Client struct {
	conn       net.Conn
	socketPath string
	timeout    time.Duration
	dbPath     string // Expected database path for validation
}

// TryConnect attempts to connect to the daemon socket
// Returns nil if no daemon is running or unhealthy
func TryConnect(socketPath string) (*Client, error) {
	return TryConnectWithTimeout(socketPath, 2*time.Second)
}

// TryConnectWithTimeout attempts to connect to the daemon socket using the provided dial timeout.
// Returns nil if no daemon is running or unhealthy.
func TryConnectWithTimeout(socketPath string, dialTimeout time.Duration) (*Client, error) {
	if !endpointExists(socketPath) {
		if os.Getenv("BD_DEBUG") != "" {
			fmt.Fprintf(os.Stderr, "Debug: RPC endpoint does not exist: %s\n", socketPath)
		}
		return nil, nil
	}

	if dialTimeout <= 0 {
		dialTimeout = 2 * time.Second
	}

	conn, err := dialRPC(socketPath, dialTimeout)
	if err != nil {
		if os.Getenv("BD_DEBUG") != "" {
			fmt.Fprintf(os.Stderr, "Debug: failed to connect to RPC endpoint: %v\n", err)
		}
		return nil, nil
	}

	client := &Client{
		conn:       conn,
		socketPath: socketPath,
		timeout:    30 * time.Second,
	}

	health, err := client.Health()
	if err != nil {
		if os.Getenv("BD_DEBUG") != "" {
			fmt.Fprintf(os.Stderr, "Debug: health check failed: %v\n", err)
		}
		_ = conn.Close()
		return nil, nil
	}

	if health.Status == "unhealthy" {
		if os.Getenv("BD_DEBUG") != "" {
			fmt.Fprintf(os.Stderr, "Debug: daemon unhealthy: %s\n", health.Error)
		}
		_ = conn.Close()
		return nil, nil
	}

	if os.Getenv("BD_DEBUG") != "" {
		fmt.Fprintf(os.Stderr, "Debug: connected to daemon (status: %s, uptime: %.1fs)\n",
			health.Status, health.Uptime)
	}

	return client, nil
}

// Close closes the connection to the daemon
func (c *Client) Close() error {
	if c.conn != nil {
		return c.conn.Close()
	}
	return nil
}

// SetTimeout sets the request timeout duration
func (c *Client) SetTimeout(timeout time.Duration) {
	c.timeout = timeout
}

// SetDatabasePath sets the expected database path for validation
func (c *Client) SetDatabasePath(dbPath string) {
	c.dbPath = dbPath
}

// Execute sends an RPC request and waits for a response
func (c *Client) Execute(operation string, args interface{}) (*Response, error) {
	return c.ExecuteWithCwd(operation, args, "")
}

// ExecuteWithCwd sends an RPC request with an explicit cwd (or current dir if empty string)
func (c *Client) ExecuteWithCwd(operation string, args interface{}, cwd string) (*Response, error) {
	argsJSON, err := json.Marshal(args)
	if err != nil {
		return nil, fmt.Errorf("failed to marshal args: %w", err)
	}

	// Use provided cwd, or get current working directory for database routing
	if cwd == "" {
		cwd, _ = os.Getwd()
	}

	req := Request{
		Operation:     operation,
		Args:          argsJSON,
		ClientVersion: ClientVersion,
		Cwd:           cwd,
		ExpectedDB:    c.dbPath, // Send expected database path for validation
	}

	reqJSON, err := json.Marshal(req)
	if err != nil {
		return nil, fmt.Errorf("failed to marshal request: %w", err)
	}

	if c.timeout > 0 {
		deadline := time.Now().Add(c.timeout)
		if err := c.conn.SetDeadline(deadline); err != nil {
			return nil, fmt.Errorf("failed to set deadline: %w", err)
		}
	}

	writer := bufio.NewWriter(c.conn)
	if _, err := writer.Write(reqJSON); err != nil {
		return nil, fmt.Errorf("failed to write request: %w", err)
	}
	if err := writer.WriteByte('\n'); err != nil {
		return nil, fmt.Errorf("failed to write newline: %w", err)
	}
	if err := writer.Flush(); err != nil {
		return nil, fmt.Errorf("failed to flush: %w", err)
	}

	reader := bufio.NewReader(c.conn)
	respLine, err := reader.ReadBytes('\n')
	if err != nil {
		return nil, fmt.Errorf("failed to read response: %w", err)
	}

	var resp Response
	if err := json.Unmarshal(respLine, &resp); err != nil {
		return nil, fmt.Errorf("failed to unmarshal response: %w", err)
	}

	if !resp.Success {
		return &resp, fmt.Errorf("operation failed: %s", resp.Error)
	}

	return &resp, nil
}

// Ping sends a ping request to verify the daemon is alive
func (c *Client) Ping() error {
	resp, err := c.Execute(OpPing, nil)
	if err != nil {
		return err
	}

	if !resp.Success {
		return fmt.Errorf("ping failed: %s", resp.Error)
	}

	return nil
}

// Status retrieves daemon status metadata
func (c *Client) Status() (*StatusResponse, error) {
	resp, err := c.Execute(OpStatus, nil)
	if err != nil {
		return nil, err
	}

	var status StatusResponse
	if err := json.Unmarshal(resp.Data, &status); err != nil {
		return nil, fmt.Errorf("failed to unmarshal status response: %w", err)
	}

	return &status, nil
}

// Health sends a health check request to verify the daemon is healthy
func (c *Client) Health() (*HealthResponse, error) {
	resp, err := c.Execute(OpHealth, nil)
	if err != nil {
		return nil, err
	}

	var health HealthResponse
	if err := json.Unmarshal(resp.Data, &health); err != nil {
		return nil, fmt.Errorf("failed to unmarshal health response: %w", err)
	}

	return &health, nil
}

// Shutdown sends a graceful shutdown request to the daemon
func (c *Client) Shutdown() error {
	_, err := c.Execute(OpShutdown, nil)
	return err
}

// Metrics retrieves daemon metrics
func (c *Client) Metrics() (*MetricsSnapshot, error) {
	resp, err := c.Execute(OpMetrics, nil)
	if err != nil {
		return nil, err
	}

	var metrics MetricsSnapshot
	if err := json.Unmarshal(resp.Data, &metrics); err != nil {
		return nil, fmt.Errorf("failed to unmarshal metrics response: %w", err)
	}

	return &metrics, nil
}

// Create creates a new issue via the daemon
func (c *Client) Create(args *CreateArgs) (*Response, error) {
	return c.Execute(OpCreate, args)
}

// Update updates an issue via the daemon
func (c *Client) Update(args *UpdateArgs) (*Response, error) {
	return c.Execute(OpUpdate, args)
}

// CloseIssue marks an issue as closed via the daemon.
func (c *Client) CloseIssue(args *CloseArgs) (*Response, error) {
	return c.Execute(OpClose, args)
}

// List lists issues via the daemon
func (c *Client) List(args *ListArgs) (*Response, error) {
	return c.Execute(OpList, args)
}

// Show shows an issue via the daemon
func (c *Client) Show(args *ShowArgs) (*Response, error) {
	return c.Execute(OpShow, args)
}

// ResolveID resolves a partial issue ID to a full ID via the daemon
func (c *Client) ResolveID(args *ResolveIDArgs) (*Response, error) {
	return c.Execute(OpResolveID, args)
}

// Ready gets ready work via the daemon
func (c *Client) Ready(args *ReadyArgs) (*Response, error) {
	return c.Execute(OpReady, args)
}

// Stale gets stale issues via the daemon
func (c *Client) Stale(args *StaleArgs) (*Response, error) {
	return c.Execute(OpStale, args)
}

// Stats gets statistics via the daemon
func (c *Client) Stats() (*Response, error) {
	return c.Execute(OpStats, nil)
}

// AddDependency adds a dependency via the daemon
func (c *Client) AddDependency(args *DepAddArgs) (*Response, error) {
	return c.Execute(OpDepAdd, args)
}

// RemoveDependency removes a dependency via the daemon
func (c *Client) RemoveDependency(args *DepRemoveArgs) (*Response, error) {
	return c.Execute(OpDepRemove, args)
}

// AddLabel adds a label via the daemon
func (c *Client) AddLabel(args *LabelAddArgs) (*Response, error) {
	return c.Execute(OpLabelAdd, args)
}

// RemoveLabel removes a label via the daemon
func (c *Client) RemoveLabel(args *LabelRemoveArgs) (*Response, error) {
	return c.Execute(OpLabelRemove, args)
}

// ListComments retrieves comments for an issue via the daemon
func (c *Client) ListComments(args *CommentListArgs) (*Response, error) {
	return c.Execute(OpCommentList, args)
}

// AddComment adds a comment to an issue via the daemon
func (c *Client) AddComment(args *CommentAddArgs) (*Response, error) {
	return c.Execute(OpCommentAdd, args)
}

// Batch executes multiple operations atomically
func (c *Client) Batch(args *BatchArgs) (*Response, error) {
	return c.Execute(OpBatch, args)
}



// Export exports the database to JSONL format
func (c *Client) Export(args *ExportArgs) (*Response, error) {
	return c.Execute(OpExport, args)
}

// EpicStatus gets epic completion status via the daemon
func (c *Client) EpicStatus(args *EpicStatusArgs) (*Response, error) {
	return c.Execute(OpEpicStatus, args)
}