package main

import (
	"bytes"
	"compress/gzip"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"time"
)

// APIClient handles communication with the server
type APIClient struct {
	baseURL    string
	token      string
	httpClient *http.Client
}

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

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

// RegistrationRequest is sent to register a device
type RegistrationRequest struct {
	DeviceID string  `json:"device_id"`
	EthIP    *string `json:"eth_ip,omitempty"`
	WlanIP   *string `json:"wlan_ip,omitempty"`
}

// RegistrationResponse is returned from registration
type RegistrationResponse struct {
	DeviceToken    string `json:"device_token"`
	DevicePassword string `json:"device_password,omitempty"`
	SSHTunnel      struct {
		Enabled    bool   `json:"enabled"`
		RemotePort int    `json:"remote_port"`
		Server     string `json:"server"`
	} `json:"ssh_tunnel,omitempty"`
}

// Register registers a device with the server
func (c *APIClient) Register(req *RegistrationRequest) (*RegistrationResponse, error) {
	body, err := json.Marshal(req)
	if err != nil {
		return nil, err
	}

	httpReq, err := http.NewRequest("POST", c.baseURL+"/registration", bytes.NewReader(body))
	if err != nil {
		return nil, err
	}
	httpReq.Header.Set("Content-Type", "application/json")

	resp, err := c.httpClient.Do(httpReq)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != 201 && resp.StatusCode != 200 {
		respBody, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("registration failed: %d %s", resp.StatusCode, string(respBody))
	}

	var regResp RegistrationResponse
	if err := json.NewDecoder(resp.Body).Decode(&regResp); err != nil {
		return nil, err
	}

	return &regResp, nil
}

// ServerConfig is the configuration returned by the server
type ServerConfig struct {
	// ForceCloud overrides local mode setting - for remote support
	ForceCloud bool `json:"force_cloud"`

	BLE struct {
		Enabled         bool   `json:"enabled"`
		BatchIntervalMs int    `json:"batch_interval_ms"`
		UUIDFilterHex   string `json:"uuid_filter_hex,omitempty"`
	} `json:"ble"`
	WiFi struct {
		MonitorEnabled  bool   `json:"monitor_enabled"`
		ClientEnabled   bool   `json:"client_enabled"`
		SSID            string `json:"ssid"`
		PSK             string `json:"psk"`
		BatchIntervalMs int    `json:"batch_interval_ms"`
	} `json:"wifi"`
	SSHTunnel struct {
		Enabled           bool   `json:"enabled"`
		Server            string `json:"server"`
		Port              int    `json:"port"`
		User              string `json:"user"`
		RemotePort        int    `json:"remote_port"`
		KeepaliveInterval int    `json:"keepalive_interval"`
	} `json:"ssh_tunnel"`
	Net struct {
		NTP struct {
			Servers []string `json:"servers"`
		} `json:"ntp"`
	} `json:"net"`
	Debug bool `json:"debug"`
}

// GetConfig fetches configuration from the server
func (c *APIClient) GetConfig(deviceID string) (*ServerConfig, error) {
	httpReq, err := http.NewRequest("GET", c.baseURL+"/config", nil)
	if err != nil {
		return nil, err
	}

	q := httpReq.URL.Query()
	q.Set("device_id", deviceID)
	httpReq.URL.RawQuery = q.Encode()

	if c.token != "" {
		httpReq.Header.Set("Authorization", "Bearer "+c.token)
	}

	resp, err := c.httpClient.Do(httpReq)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		return nil, fmt.Errorf("config fetch failed: %d", resp.StatusCode)
	}

	var cfg ServerConfig
	if err := json.NewDecoder(resp.Body).Decode(&cfg); err != nil {
		return nil, err
	}

	return &cfg, nil
}

// EventBatch is a batch of events to upload
type EventBatch struct {
	DeviceID string        `json:"device_id"`
	Events   []interface{} `json:"events"`
}

// UploadEvents uploads a batch of events (gzipped)
func (c *APIClient) UploadEvents(endpoint string, batch *EventBatch) error {
	// Serialize to JSON
	jsonData, err := json.Marshal(batch)
	if err != nil {
		return err
	}

	// Gzip compress
	var buf bytes.Buffer
	gw := gzip.NewWriter(&buf)
	if _, err := gw.Write(jsonData); err != nil {
		return err
	}
	if err := gw.Close(); err != nil {
		return err
	}

	// Store compressed data for retries
	compressedData := buf.Bytes()
	url := c.baseURL + endpoint

	// Send with retries
	var lastErr error
	for attempt := 1; attempt <= 3; attempt++ {
		// Create fresh request for each attempt (body can only be read once)
		httpReq, err := http.NewRequest("POST", url, bytes.NewReader(compressedData))
		if err != nil {
			return err
		}

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

		resp, err := c.httpClient.Do(httpReq)
		if err != nil {
			lastErr = err
			time.Sleep(time.Duration(attempt) * time.Second)
			continue
		}
		resp.Body.Close()

		if resp.StatusCode >= 200 && resp.StatusCode < 300 {
			return nil
		}
		lastErr = fmt.Errorf("upload failed: %d", resp.StatusCode)
		time.Sleep(time.Duration(attempt) * time.Second)
	}

	return lastErr
}