advent-of-code/2025/cmd/generate/fetch_input.go

92 lines
1.9 KiB
Go

package generate
import (
"fmt"
"io"
"net/http"
"net/http/cookiejar"
"net/url"
"os"
)
const (
baseURL = "https://adventofcode.com/2025/day/%d/input"
host = "adventofcode.com"
userAgent = "github.com/C4theBomb/advent-of-code by c4patino@gmail.com"
cookieEnvName = "COOKIE"
)
func getCookie() (string, error) {
cookieValue := os.Getenv(cookieEnvName)
if cookieValue == "" {
return "", fmt.Errorf("%s environment variable not set", cookieEnvName)
}
return cookieValue, nil
}
func createHTTPClient(cookieValue string) (*http.Client, error) {
jar, err := cookiejar.New(nil)
if err != nil {
return nil, fmt.Errorf("failed to create cookie jar: %w", err)
}
domainURL := &url.URL{Scheme: "https", Host: host}
client := &http.Client{Jar: jar}
jar.SetCookies(domainURL, []*http.Cookie{{Name: "session", Value: cookieValue}})
return client, nil
}
func fetchInput(client *http.Client, day int) ([]byte, error) {
url := fmt.Sprintf(baseURL, day)
req, err := http.NewRequest("GET", url, nil)
if err != nil {
return nil, fmt.Errorf("failed to create request: %w", err)
}
req.Header.Set("User-Agent", userAgent)
resp, err := client.Do(req)
if err != nil {
return nil, fmt.Errorf("request failed: %w", err)
}
defer resp.Body.Close()
body, err := io.ReadAll(resp.Body)
if err != nil {
return nil, fmt.Errorf("failed to read response body: %w", err)
}
if resp.StatusCode != http.StatusOK {
return nil, fmt.Errorf("unexpected status code %d: %s", resp.StatusCode, string(body))
}
return body, nil
}
func retrieveInput(day int) error {
cookieValue, err := getCookie()
if err != nil {
return err
}
client, err := createHTTPClient(cookieValue)
if err != nil {
return err
}
body, err := fetchInput(client, day)
if err != nil {
return err
}
filename := fmt.Sprintf("./day%02d/input.txt", day)
if err := os.WriteFile(filename, []byte(body), 0755); err != nil {
return err
}
return nil
}