package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
)

const API string = "https://pkgstats.archlinux.de/api/"

type PkgPopularity struct {
	Name         string
	Popularities []float64
}

type PackagePopularity struct {
	Name       string  `json:"name"`
	Samples    int     `json:"samples"`
	Count      int     `json:"count"`
	Popularity float64 `json:"popularity"`
	StartMonth int     `json:"startMonth"`
	EndMonth   int     `json:"endMonth"`
}

type Response struct {
	Total               int                 `json:"total"`
	Count               int                 `json:"count"`
	Limit               int                 `json:"limit"`
	Offset              int                 `json:"offset"`
	Query               interface{}         `json:"query"`
	PackagePopularities []PackagePopularity `json:"packagePopularities"`
}

func main() {
	/*browsers := []string{"firefox", "chromium", "google-chrome", "epiphany", "konqueror", "tor-browser", "vivaldi", "opera", "midori"}
	fmt.Println(get_popularities(browsers))*/
	get_trending_packages()
}

func get_trending_packages() {
	fmt.Println(get_popularities(get_package_names()))
}

func get_popularities(pkgs []string) []PkgPopularity {
	var popularities []PkgPopularity
	for _, pkg := range pkgs {
		popularities = append(popularities, PkgPopularity{pkg, get_package_monthly_popularity(pkg)})
	}
	return popularities
}

func get_total_packages() int {
	var response Response
	response = requestJSON("packages?limit=1")
	return response.Total
}

func get_package_names() []string {
	var packages []string
	var total = 50 // get_total_packages()
	var offset, limit int = 0, 100

	for offset < total {
		relURL := "packages?limit=" + fmt.Sprint(limit) + "&offset=" + fmt.Sprint(offset)
		var response Response
		response = requestJSON(relURL)
		for _, pkg := range response.PackagePopularities {
			packages = append(packages, pkg.Name)
		}
		offset += limit
	}
	return packages
}

func get_package_monthly_popularity(pkg string) []float64 {
	relURL := "packages/" + pkg + "/series?startMonth=201009"
	var response Response
	response = requestJSON(relURL)
	var popularities []float64
	for _, pkg := range response.PackagePopularities {
		popularities = append(popularities, pkg.Popularity)
	}
	return popularities
}

func requestJSON(relURL string) Response {
	resp, err := http.Get(API + relURL)
	if err != nil {
		log.Fatal(err)
	}
	defer resp.Body.Close()

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		log.Fatal(err)
	}

	var response Response
	err = json.Unmarshal(body, &response)
	if err != nil {
		log.Fatal(err)
	}
	return response
}