package client

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
	"time"

	"github.com/gorilla/websocket"
)

// Client is a GraphQL client for the ARP API
type Client struct {
	baseURL    string
	httpClient *http.Client
	token      string
}

// New creates a new GraphQL client
func New(baseURL string) *Client {
	return &Client{
		baseURL: baseURL,
		httpClient: &http.Client{
			Timeout: 30 * time.Second,
		},
	}
}

// SetToken sets the authentication token
func (c *Client) SetToken(token string) {
	c.token = token
}

// GraphQLRequest represents a GraphQL request
type GraphQLRequest struct {
	Query         string                 `json:"query"`
	Variables     map[string]interface{} `json:"variables,omitempty"`
	OperationName string                 `json:"operationName,omitempty"`
}

// GraphQLResponse represents a GraphQL response
type GraphQLResponse struct {
	Data   json.RawMessage `json:"data,omitempty"`
	Errors []GraphQLError  `json:"errors,omitempty"`
}

// GraphQLError represents a GraphQL error
type GraphQLError struct {
	Message   string `json:"message"`
	Locations []struct {
		Line   int `json:"line"`
		Column int `json:"column"`
	} `json:"locations,omitempty"`
	Path []interface{} `json:"path,omitempty"`
}

// Error returns the error message
func (e GraphQLError) Error() string {
	return e.Message
}

// Query executes a GraphQL query
func (c *Client) Query(query string, variables map[string]interface{}) (*GraphQLResponse, error) {
	return c.doRequest(query, variables, "")
}

// Mutation executes a GraphQL mutation
func (c *Client) Mutation(query string, variables map[string]interface{}) (*GraphQLResponse, error) {
	return c.doRequest(query, variables, "")
}

func (c *Client) doRequest(query string, variables map[string]interface{}, operationName string) (*GraphQLResponse, error) {
	reqBody := GraphQLRequest{
		Query:         query,
		Variables:     variables,
		OperationName: operationName,
	}

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

	req, err := http.NewRequest("POST", c.baseURL, bytes.NewReader(bodyBytes))
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("Content-Type", "application/json")
	if c.token != "" {
		req.Header.Set("Authorization", "Bearer "+c.token)
	}

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("request failed: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("failed to read response: %w", err)
	}

	var gqlResp GraphQLResponse
	if err := json.Unmarshal(body, &gqlResp); err != nil {
		return nil, fmt.Errorf("failed to parse response: %w", err)
	}

	if len(gqlResp.Errors) > 0 {
		return &gqlResp, fmt.Errorf("GraphQL error: %s", gqlResp.Errors[0].Message)
	}

	return &gqlResp, nil
}

// WebSocketClient handles GraphQL subscriptions
type WebSocketClient struct {
	conn     *websocket.Conn
	baseURL  string
	token    string
	done     chan struct{}
	messages chan json.RawMessage
	errors   chan error
}

// NewWebSocketClient creates a new WebSocket client for subscriptions
func NewWebSocketClient(baseURL string, token string) *WebSocketClient {
	// Convert HTTP URL to WebSocket URL
	wsURL := strings.Replace(baseURL, "http://", "ws://", 1)
	wsURL = strings.Replace(wsURL, "https://", "wss://", 1)

	return &WebSocketClient{
		baseURL:  wsURL,
		token:    token,
		done:     make(chan struct{}),
		messages: make(chan json.RawMessage, 100),
		errors:   make(chan error, 10),
	}
}

// Connect establishes a WebSocket connection
func (w *WebSocketClient) Connect() error {
	u, err := url.Parse(w.baseURL)
	if err != nil {
		return fmt.Errorf("failed to parse URL: %w", err)
	}

	headers := http.Header{}
	if w.token != "" {
		headers.Set("Authorization", "Bearer "+w.token)
	}

	dialer := websocket.DefaultDialer
	conn, _, err := dialer.Dial(u.String(), headers)
	if err != nil {
		return fmt.Errorf("failed to connect: %w", err)
	}
	w.conn = conn

	// Send connection init
	initMsg := map[string]interface{}{
		"type": "connection_init",
		"payload": map[string]interface{}{
			"Authorization": "Bearer " + w.token,
		},
	}
	if err := w.conn.WriteJSON(initMsg); err != nil {
		return fmt.Errorf("failed to send init: %w", err)
	}

	// Wait for connection_ack
	_, msg, err := w.conn.ReadMessage()
	if err != nil {
		return fmt.Errorf("failed to read ack: %w", err)
	}

	var ack map[string]interface{}
	if err := json.Unmarshal(msg, &ack); err != nil {
		return fmt.Errorf("failed to parse ack: %w", err)
	}

	if ack["type"] != "connection_ack" {
		return fmt.Errorf("expected connection_ack, got: %s", ack["type"])
	}

	// Start reading messages
	go w.readMessages()

	return nil
}

// Subscribe starts a subscription
func (w *WebSocketClient) Subscribe(id string, query string, variables map[string]interface{}) error {
	subMsg := map[string]interface{}{
		"id":   id,
		"type": "start",
		"payload": map[string]interface{}{
			"query":     query,
			"variables": variables,
		},
	}
	return w.conn.WriteJSON(subMsg)
}

// Unsubscribe stops a subscription
func (w *WebSocketClient) Unsubscribe(id string) error {
	stopMsg := map[string]interface{}{
		"id":   id,
		"type": "stop",
	}
	return w.conn.WriteJSON(stopMsg)
}

// Messages returns the message channel
func (w *WebSocketClient) Messages() <-chan json.RawMessage {
	return w.messages
}

// Errors returns the error channel
func (w *WebSocketClient) Errors() <-chan error {
	return w.errors
}

// Done returns the done channel
func (w *WebSocketClient) Done() <-chan struct{} {
	return w.done
}

func (w *WebSocketClient) readMessages() {
	defer close(w.done)
	defer close(w.messages)
	defer close(w.errors)

	for {
		_, msg, err := w.conn.ReadMessage()
		if err != nil {
			select {
			case w.errors <- err:
			default:
			}
			return
		}

		var parsed map[string]interface{}
		if err := json.Unmarshal(msg, &parsed); err != nil {
			continue
		}

		msgType, ok := parsed["type"].(string)
		if !ok {
			continue
		}

		switch msgType {
		case "data":
			if payload, ok := parsed["payload"].(map[string]interface{}); ok {
				if data, ok := payload["data"]; ok {
					dataBytes, _ := json.Marshal(data)
					select {
					case w.messages <- dataBytes:
					default:
					}
				}
				if errs, ok := payload["errors"].([]interface{}); ok && len(errs) > 0 {
					if errBytes, err := json.Marshal(errs); err == nil {
						w.errors <- fmt.Errorf("subscription error: %s", string(errBytes))
					}
				}
			}
		case "complete":
			return
		case "error":
			if payload, ok := parsed["payload"].([]interface{}); ok {
				if errBytes, err := json.Marshal(payload); err == nil {
					w.errors <- fmt.Errorf("subscription error: %s", string(errBytes))
				}
			}
		}
	}
}

// Close closes the WebSocket connection
func (w *WebSocketClient) Close() error {
	if w.conn != nil {
		return w.conn.Close()
	}
	return nil
}