package de

import (
	"fmt"
	"log/slog"
	"net/http"
	"net/url"
	"strings"

	"github.com/antchfx/htmlquery"
	"golang.org/x/text/encoding/charmap"
	"golang.org/x/text/transform"
	"push-f.com/lex-surf/internal/lex"
	"push-f.com/lex-surf/lex-fetch/progress"
)

type Fetcher struct{}

var pages = []rune("ABCDEFGHIJKLMNOPQRSTUVWYZ123456789")

func (s *Fetcher) Fetch(log *slog.Logger, client *http.Client, progress *progress.Reporter) ([]lex.Law, error) {
	progress.Total = len(pages)
	var laws []lex.Law
	for i := range len(pages) {
		resp, err := client.Get(fmt.Sprintf("https://www.gesetze-im-internet.de/Teilliste_%c.html", pages[i]))
		if err != nil {
			return nil, fmt.Errorf("failed to fetch page: %w", err)
		}
		if resp.StatusCode != 200 {
			return nil, fmt.Errorf("unexpected status code %d", resp.StatusCode)
		}
		reader := transform.NewReader(resp.Body, charmap.ISO8859_1.NewDecoder())
		doc, err := htmlquery.Parse(reader)
		if err != nil {
			return nil, fmt.Errorf("failed to HTML parse: %w", err)
		}
		div := htmlquery.FindOne(doc, "//div[@id='paddingLR12']")
		if div == nil {
			return nil, fmt.Errorf("didn't find expected HTML div")
		}
		for child := range div.ChildNodes() {
			if child.FirstChild != nil {
				href := htmlquery.SelectAttr(child.FirstChild, "href")
				redir, ok := strings.CutPrefix(href, "./")
				if !ok {
					return nil, fmt.Errorf("expected href to start with ./ but found %s", href)
				}
				redir, ok = strings.CutSuffix(redir, "/index.html")
				if !ok {
					return nil, fmt.Errorf("expected href to end with /index.html but found %s", href)
				}

				hrefUrl, _ := url.Parse(href)

				laws = append(laws, lex.Law{
					URL:   resp.Request.URL.ResolveReference(hrefUrl).String(),
					Title: strings.TrimSpace(child.FirstChild.NextSibling.NextSibling.Data),
					Redir: redir,
					Abbr:  redir,
				})
			}
		}
		progress.ReportProgress(i + 1)
	}
	return laws, nil
}