//go:build ignore

package main

import (
	"flag"
	"fmt"
	"io"
	"net/http"
	"os"
	"regexp"

	"github.com/ayn2op/arikawa/v3/api"
)

const format = `// GENERATED BY go generate; DO NOT EDIT.

package %s

const clientBuildNumber = %s
`

var buildNumberRegex = regexp.MustCompile(`"BUILD_NUMBER":\s*"(\d+)"`)

func fetchBuildNumber() (string, error) {
	resp, err := http.Get(api.BaseEndpoint + "/login")
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
		return "", fmt.Errorf("failed to fetch login page; status=%q", resp.Status)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", err
	}

	matches := buildNumberRegex.FindSubmatch(body)
	if len(matches) < 2 {
		return "", fmt.Errorf("failed to find build number; matches=%v", matches)
	}
	return string(matches[1]), nil
}

func main() {
	out := flag.String("out", "generated.go", "out filename")
	flag.Parse()

	buildNumber, err := fetchBuildNumber()
	if err != nil {
		panic(err)
	}

	packageName := os.Getenv("GOPACKAGE")
	if packageName == "" {
		panic("GOPACKAGE is not set; run with go generate")
	}

	content := fmt.Appendf(nil, format, packageName, buildNumber)
	if err := os.WriteFile(*out, content, 0644); err != nil {
		panic(err)
	}
}