package classes

import (
	"context"
	"strconv"
	"strings"

	"git.golem15.com/golem15/sm-sitemap-plugin/contract"
	"git.golem15.com/golem15/sm-sitemap-plugin/models"
	"git.golem15.com/golem15/summercms/modules/backpack"
	"gorm.io/gorm"
)

// Listing implements contract.Listing over the slot table and the
// settings (D-95): other plugins read the site address, the index address,
// the file groups and each group's listed addresses without importing the
// sitemap plugin.
type Listing struct {
	App *backpack.App
}

var _ contract.Listing = Listing{}

// The page sizes of Entries.
const (
	defaultEntriesLimit = 100
	maxEntriesLimit     = 1000
)

func (l Listing) db(ctx context.Context) (*gorm.DB, error) {
	if l.App == nil {
		return nil, ErrNoDatabase
	}
	db, ok := l.App.Lookup[*gorm.DB]()
	if !ok || db == nil {
		return nil, ErrNoDatabase
	}
	return db.WithContext(ctx), nil
}

// Settings answers the site address, the index address, the default
// locale and the groups with listed addresses (by key), with their titles
// (a content type's saved HTML sitemap headings, else the titles of the
// published Filter's group of that key), the HTML sitemap settings and the
// IndexNow key file name (while IndexNow is on with a key).
func (l Listing) Settings(ctx context.Context) (contract.ListingSettings, error) {
	var out contract.ListingSettings
	db, err := l.db(ctx)
	if err != nil {
		return out, err
	}
	settings, err := LoadSettings(db)
	if err != nil {
		return out, err
	}
	out.SiteURL = SiteURL(l.App, settings)
	if out.SiteURL != "" {
		out.IndexURL = out.SiteURL + "/sitemap.xml"
	}
	out.DefaultLocale = models.Text(settings.DefaultLocale)
	var counts []struct {
		Grp string `gorm:"column:grp"`
		N   int    `gorm:"column:n"`
	}
	if err := db.Raw(`SELECT grp, COUNT(*) AS n FROM golem15_sitemap_urls WHERE excluded_reason = '' GROUP BY grp ORDER BY grp`).Scan(&counts).Error; err != nil {
		return out, err
	}
	titles, _, _, err := groupTitles(ctx, l.App, db)
	if err != nil {
		return out, err
	}
	out.Groups = make([]contract.GroupInfo, 0, len(counts))
	for _, c := range counts {
		out.Groups = append(out.Groups, contract.GroupInfo{Key: c.Grp, Slug: c.Grp, Titles: titles[c.Grp], Count: c.N})
	}
	out.HTMLEnabled = settings.HTMLEnabled
	out.HTMLPaths = settings.EffectiveHTMLPaths()
	out.HTMLPageSize = settings.EffectiveHTMLPageSize()
	out.KeyFile = KeyFileName(ActiveKey(settings))
	return out, nil
}

// Entries pages a group's listed addresses in the order they were stored
// (row id); Next is the last row id of a page that has a successor. A
// Locale keeps the addresses of that locale and those without one.
func (l Listing) Entries(ctx context.Context, q contract.EntriesQuery) (contract.EntriesPage, error) {
	page := contract.EntriesPage{Entries: []contract.Entry{}}
	db, err := l.db(ctx)
	if err != nil {
		return page, err
	}
	settings, err := LoadSettings(db)
	if err != nil {
		return page, err
	}
	site := SiteURL(l.App, settings)
	limit := q.Limit
	if limit <= 0 {
		limit = defaultEntriesLimit
	}
	limit = min(limit, maxEntriesLimit)
	scope := func() *gorm.DB {
		s := db.Model(&models.URL{}).Where("grp = ? AND excluded_reason = ''", q.Group)
		if loc := strings.TrimSpace(q.Locale); loc != "" {
			s = s.Where("locale = ? OR locale = ''", loc)
		}
		return s
	}
	var total int64
	if err := scope().Count(&total).Error; err != nil {
		return page, err
	}
	page.Total = int(total)
	q2 := scope()
	if after, err := strconv.ParseUint(strings.TrimSpace(q.After), 10, 64); err == nil && after > 0 {
		q2 = q2.Where("id > ?", after)
	}
	var rows []models.URL
	if err := q2.Order("id ASC").Limit(limit + 1).Find(&rows).Error; err != nil {
		return page, err
	}
	if len(rows) > limit {
		rows = rows[:limit]
		page.Next = strconv.FormatUint(rows[len(rows)-1].ID, 10)
	}
	for _, r := range rows {
		page.Entries = append(page.Entries, contract.Entry{
			Group:    r.Grp,
			TypeKey:  r.TypeKey,
			RecordID: r.RecordID,
			Locale:   r.Locale,
			URL:      Absolute(site, r.URL),
			Title:    r.Title,
			LastMod:  r.LastMod,
		})
	}
	return page, nil
}