package providers

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
)

const maxOAuthResponseBodyBytes = 1 << 20

func postFormWithContext(ctx context.Context, client *http.Client, endpoint string, data url.Values) (*http.Response, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, strings.NewReader(data.Encode()))
	if err != nil {
		return nil, err
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	return client.Do(req)
}

func readOAuthResponseBody(resp *http.Response) ([]byte, error) {
	limited := io.LimitReader(resp.Body, maxOAuthResponseBodyBytes+1)
	body, err := io.ReadAll(limited)
	if err != nil {
		return nil, err
	}
	if len(body) > maxOAuthResponseBodyBytes {
		return nil, fmt.Errorf("oauth response body exceeded %d bytes", maxOAuthResponseBodyBytes)
	}
	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
		snippet := strings.TrimSpace(string(body))
		if len(snippet) > 256 {
			snippet = snippet[:256]
		}
		if snippet == "" {
			return nil, fmt.Errorf("oauth request failed with status %d", resp.StatusCode)
		}
		return nil, fmt.Errorf("oauth request failed with status %d: %s", resp.StatusCode, snippet)
	}
	return body, nil
}