package application

import (
	"fmt"
	"net/http"
	"os"
	"time"

	"github.com/gorilla/mux"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	log "github.com/sirupsen/logrus"
	"gopkg.in/yaml.v2"
	"lostak.dev/pve-exporter/configuration"
	"lostak.dev/pve-exporter/metrics"
	"lostak.dev/pve-exporter/proxmox"
)

// Application context.
type Application struct {
	Configuration  *configuration.Configuration // Application configuration.
	Router         *mux.Router                  // Gorilla MUX router instance.
	Server         *http.Server                 // HTTP server instance.
	MetricsManager *metrics.PveMetricsManager   // PVE metrics manager.
	PveApiClient   *proxmox.PveApiClient        // PVE API client instance.
}

// Create new instance of the PVE exporter.
func NewApplication(configPath string) *Application {
	app := Application{}
	app.Router = mux.NewRouter()

	// Load configuration file.
	file, err := os.ReadFile(configPath)
	if err != nil {
		log.Panicf("Can't open config.yaml. Error: %s.", err)
	}

	// Unmarshal configuration file.
	if err := yaml.Unmarshal(file, &app.Configuration); err != nil {
		log.Panicf("Can't parse config.yaml. Error: %s.", err)
	}

	// Validate configuration file.
	err = app.Configuration.Validate()
	if err != nil {
		log.Fatalf("Configuration error: %s", err)
	}

	// Set log level.
	log.SetLevel(log.AllLevels[app.Configuration.LogLevel])

	// Create proxmox API client instance.
	pvec := app.Configuration.PVE
	app.PveApiClient = proxmox.NewPveApiClient(pvec.Hosts, pvec.Token.TokenId, pvec.Token.Secret)

	// Create metrics collector.
	app.MetricsManager = metrics.NewPveMetricsManager(app.PveApiClient, &app.Configuration.PVE)

	return &app
}

// Initialize application internals such as HTTP server, router, PVE metrics scraper.
func (app *Application) Start() {
	// Prepare web server.
	hostaddr := fmt.Sprintf("%s:%d", app.Configuration.Host, app.Configuration.Port)
	app.Server = &http.Server{
		Handler:      app.Router,
		Addr:         hostaddr,
		WriteTimeout: 15 * time.Second,
		ReadTimeout:  15 * time.Second,
	}

	// Prepare metrics handler
	app.Router.Handle("/metrics", promhttp.Handler())

	// Start the metrics manager.
	app.MetricsManager.Start()

	log.Infof("Proxmox exporter started on %s.", hostaddr)
	log.Fatal(app.Server.ListenAndServe())
}