package extsvc

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

// hrdlogUploadURL is HRDLog.net's real-time upload endpoint. It accepts a
// form-encoded POST with the uploader's callsign, the account's secret upload
// Code (HRDLog account → "My Account" → upload code), an App identifier, and
// one ADIF record.
const hrdlogUploadURL = "https://robot.hrdlog.net/NewEntry.aspx"

// hrdlogApp is the App identifier sent to HRDLog so uploads are attributed to
// OpsLog in the user's HRDLog activity.
const hrdlogApp = "OpsLog"

// hrdlogPost performs the form POST to NewEntry.aspx and returns the raw
// response body. The endpoint replies HTTP 200 with a small XML document even
// for errors; callers classify it via the markers in classifyHRDLog.
func hrdlogPost(ctx context.Context, client *http.Client, callsign, code, adif string) (string, error) {
	form := url.Values{}
	form.Set("Callsign", callsign)
	form.Set("Code", code)
	form.Set("App", hrdlogApp)
	form.Set("ADIFData", adif)

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, hrdlogUploadURL, strings.NewReader(form.Encode()))
	if err != nil {
		return "", fmt.Errorf("hrdlog: build request: %w", err)
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")

	if client == nil {
		client = &http.Client{Timeout: 20 * time.Second}
	}
	resp, err := client.Do(req)
	if err != nil {
		return "", fmt.Errorf("hrdlog: request failed: %w", err)
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(io.LimitReader(resp.Body, 64*1024))
	msg := strings.TrimSpace(string(body))
	if resp.StatusCode != http.StatusOK {
		if msg == "" {
			msg = fmt.Sprintf("HTTP %d", resp.StatusCode)
		}
		return msg, fmt.Errorf("hrdlog: http %d: %s", resp.StatusCode, msg)
	}
	return msg, nil
}

// authErrHRDLog returns a non-empty, human-readable reason when the response
// signals a credential problem (wrong upload code or unregistered callsign),
// or "" otherwise. Markers mirror HRDLog's documented XML replies
// ("Invalid token</error>" / "Unknown user</error>").
func authErrHRDLog(body string) string {
	b := strings.ToLower(body)
	switch {
	case strings.Contains(b, "invalid token"):
		return "invalid upload code"
	case strings.Contains(b, "unknown user"):
		return "callsign not registered at HRDLog"
	default:
		return ""
	}
}

// UploadHRDLog pushes one ADIF record to HRDLog.net. callsign is the station
// callsign the log belongs to, code is the account's upload code.
//
// Form fields (application/x-www-form-urlencoded POST):
//
//	Callsign=<station call>&Code=<upload code>&App=OpsLog&ADIFData=<one record>
//
// HRDLog replies with XML: "<insert>1" on success, "<insert>0" for a duplicate
// (already logged — treated as success so retries are idempotent), or an
// "<error>…</error>" payload otherwise.
func UploadHRDLog(ctx context.Context, client *http.Client, callsign, code, adifRecord string) (UploadResult, error) {
	callsign = strings.ToUpper(strings.TrimSpace(callsign))
	code = strings.TrimSpace(code)
	if callsign == "" {
		return UploadResult{}, fmt.Errorf("hrdlog: station callsign not set")
	}
	if code == "" {
		return UploadResult{}, fmt.Errorf("hrdlog: upload code not set")
	}
	if strings.TrimSpace(adifRecord) == "" {
		return UploadResult{}, fmt.Errorf("hrdlog: empty adif record")
	}

	body, err := hrdlogPost(ctx, client, callsign, code, adifRecord)
	if err != nil {
		return UploadResult{OK: false, Message: body}, err
	}

	b := strings.ToLower(body)
	switch {
	case strings.Contains(b, "<insert>1"):
		return UploadResult{OK: true, Message: "uploaded"}, nil
	case strings.Contains(b, "<insert>0"):
		return UploadResult{OK: true, Message: "already in logbook"}, nil
	}
	reason := authErrHRDLog(body)
	if reason == "" {
		reason = body
		if reason == "" {
			reason = "upload rejected"
		}
	}
	return UploadResult{OK: false, Message: reason}, fmt.Errorf("hrdlog: upload failed: %s", reason)
}

// NOTE: HRDLog's NewEntry.aspx inserts ONLY the first record of a multi-record
// ADIFData, so there is no batch upload — callers must POST one record per
// request (see UploadHRDLog). The bulk uploader in app.go does exactly that.

// TestHRDLog validates the configured HRDLog credentials with a REAL request:
// it posts an empty ADIF so nothing is inserted, then checks for HRDLog's auth
// errors. A wrong upload code comes back as "Invalid token", a wrong callsign
// as "Unknown user"; anything else means the credentials were accepted (HRDLog
// simply had no QSO to add).
func TestHRDLog(ctx context.Context, client *http.Client, cfg ServiceConfig) (string, error) {
	callsign := strings.ToUpper(strings.TrimSpace(cfg.Callsign))
	code := strings.TrimSpace(cfg.Code)
	if callsign == "" {
		return "", fmt.Errorf("hrdlog: station callsign not set")
	}
	if code == "" {
		return "", fmt.Errorf("hrdlog: upload code not set")
	}
	body, err := hrdlogPost(ctx, client, callsign, code, "")
	if err != nil {
		return "", err
	}
	if reason := authErrHRDLog(body); reason != "" {
		return "", fmt.Errorf("hrdlog: %s", reason)
	}
	return fmt.Sprintf("Credentials accepted — %s", callsign), nil
}