// fmi_client.go - FMI API client library
package main

import (
	"fmt"
	"io"
	"net/http"
	"net/url"
	"time"
)

// FMIClient handles FMI API interactions
type FMIClient struct {
	BaseURL       string
	HTTPClient    *http.Client
	WeatherMapper *WeatherMapper
}

// NewFMIClient creates a new FMI client
func NewFMIClient() *FMIClient {
	return &FMIClient{
		BaseURL:       "https://opendata.fmi.fi/wfs",
		HTTPClient:    &http.Client{Timeout: 30 * time.Second},
		WeatherMapper: NewWeatherMapper(),
	}
}

// GetForecast fetches and parses forecast for a location
func (c *FMIClient) GetForecast(location string) (*OWMResponse, error) {
	// Build request URL
	url, err := c.buildURL(location)
	if err != nil {
		return nil, fmt.Errorf("building URL: %w", err)
	}

	// Fetch XML data
	xmlData, err := c.fetchXML(url)
	if err != nil {
		return nil, fmt.Errorf("fetching XML: %w", err)
	}

	// Parse XML
	forecastData, err := ParseForecastXML(xmlData)
	if err != nil {
		return nil, fmt.Errorf("parsing XML: %w", err)
	}

	// Convert to OWM format
	response, err := forecastData.ToOWMResponse(c.WeatherMapper)
	if err != nil {
		return nil, fmt.Errorf("converting to OWM format: %w", err)
	}

	return response, nil
}

func (c *FMIClient) buildURL(location string) (string, error) {
	baseURL, err := url.Parse(c.BaseURL)
	if err != nil {
		return "", err
	}

	q := baseURL.Query()
	q.Set("service", "WFS")
	q.Set("version", "2.0.0")
	q.Set("request", "getFeature")
	q.Set("storedquery_id", "fmi::forecast::harmonie::surface::point::multipointcoverage")
	q.Set("place", location)
	q.Set("parameters", "Temperature,PrecipitationRate,Humidity,Pressure,dewPoint,visibility,WindSpeedMS,WindDirection,WindGust,TotalCloudCover,WeatherSymbol3")

	baseURL.RawQuery = q.Encode()
	return baseURL.String(), nil
}

func (c *FMIClient) fetchXML(url string) ([]byte, error) {
	resp, err := c.HTTPClient.Get(url)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("HTTP %d: %s", resp.StatusCode, string(body))
	}

	return io.ReadAll(resp.Body)
}