package service

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

// captainDocumentPageParserBackendImpl is the production implementation of
// CaptainDocumentPageParserBackend. It fetches a single web page and
// extracts its title and visible text content — the same logic used by
// the sync backend for individual page URLs.
type captainDocumentPageParserBackendImpl struct {
	httpClient *http.Client
}

// NewCaptainDocumentPageParserBackend creates the production page parser backend.
func NewCaptainDocumentPageParserBackend() CaptainDocumentPageParserBackend {
	return &captainDocumentPageParserBackendImpl{
		httpClient: &http.Client{Timeout: 30 * time.Second},
	}
}

func (b *captainDocumentPageParserBackendImpl) ParseCaptainDocumentPage(ctx context.Context, pageLink string) (*CaptainDocumentSyncResult, error) {
	if pageLink == "" {
		return &CaptainDocumentSyncResult{ErrorCode: "not_found"}, nil
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, pageLink, nil)
	if err != nil {
		return &CaptainDocumentSyncResult{ErrorCode: "fetch_failed"}, fmt.Errorf("create request: %w", err)
	}
	req.Header.Set("User-Agent", "GoChat-Captain/1.0")

	resp, err := b.httpClient.Do(req)
	if err != nil {
		return &CaptainDocumentSyncResult{ErrorCode: "fetch_failed"}, fmt.Errorf("fetch url: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return &CaptainDocumentSyncResult{ErrorCode: "fetch_failed"}, fmt.Errorf("HTTP %d for %s", resp.StatusCode, pageLink)
	}

	body, err := io.ReadAll(io.LimitReader(resp.Body, 5<<20)) // 5MB max
	if err != nil {
		return &CaptainDocumentSyncResult{ErrorCode: "fetch_failed"}, fmt.Errorf("read body: %w", err)
	}

	title, content := extractHTMLText(string(body))
	content = strings.TrimSpace(content)
	if content == "" {
		return &CaptainDocumentSyncResult{ErrorCode: "content_empty"}, nil
	}

	if title == "" {
		title = pageLink
	}
	return &CaptainDocumentSyncResult{
		Content: content,
		Title:   title,
	}, nil
}