package classes

import (
	"context"
	"fmt"
	"net/url"
	"reflect"
	"strings"

	"git.golem15.com/golem15/sm-seo-plugin/models"
	"git.golem15.com/golem15/sm-sitemap-plugin/contract"
	"gorm.io/gorm"
)

// The view models of the SEO partials. They hold text only (translated in
// the request locale), never a GORM model; html/template escapes every
// value.

// Callout is one P1 callout: a warning, or a plain note when Plain is
// set (the sitemap status).
type Callout struct {
	Title string
	Text  string
	Plain bool
}

// StatusView is the P1 seo_status view model.
type StatusView struct {
	Callouts []Callout
}

// EffectiveRow is one P2 row: a property, its effective value and source.
type EffectiveRow struct {
	Property string
	Value    string
	Source   string
	Mono     bool
}

// EffectiveLocale is the P2 table of one locale.
type EffectiveLocale struct {
	Heading   string
	NoURL     bool
	NoURLText string
	Rows      []EffectiveRow
}

// EffectiveView is the P2 seo_effective view model.
type EffectiveView struct {
	Staging       bool
	StagingText   string
	PropertyLabel string
	ValueLabel    string
	SourceLabel   string
	Locales       []EffectiveLocale
}

// PlaceholderRow is one P3 row.
type PlaceholderRow struct {
	Code    string
	Meaning string
}

// PlaceholdersView is the P3 placeholders view model.
type PlaceholdersView struct {
	Caption      string
	CodeLabel    string
	MeaningLabel string
	Rows         []PlaceholderRow
}

// PhraseCtx translates key with params in the request locale; without a
// translator it returns the key.
func (s *Service) PhraseCtx(ctx context.Context, key string, params map[string]string) string {
	tr := s.translator()
	if tr == nil {
		return key
	}
	return tr.Get(ctx, key, params)
}

// effectiveProperties are the P2 rows in order: value name, label key,
// monospace.
var effectiveProperties = []struct {
	name  string
	label string
	mono  bool
}{
	{"title", "golem15.seo::lang.field.title", false},
	{"description", "golem15.seo::lang.field.description", false},
	{"canonical", "golem15.seo::lang.field.canonical", true},
	{"robots", "golem15.seo::lang.field.robots", false},
	{"og_title", "golem15.seo::lang.field.og_title", false},
	{"og_description", "golem15.seo::lang.field.og_description", false},
	{"og_image", "golem15.seo::lang.field.og_image", true},
}

// EffectiveRows turns a resolve answer into P2 rows.
func (s *Service) EffectiveRows(ctx context.Context, res Result) []EffectiveRow {
	if res.SEO == nil {
		return nil
	}
	values := map[string]string{
		"title": res.SEO.Title, "description": res.SEO.Description, "canonical": res.SEO.Canonical,
		"robots": res.SEO.Robots, "og_title": res.SEO.OG.Title, "og_description": res.SEO.OG.Description, "og_image": res.SEO.OG.Image,
	}
	out := make([]EffectiveRow, 0, len(effectiveProperties))
	for _, p := range effectiveProperties {
		out = append(out, EffectiveRow{
			Property: s.PhraseCtx(ctx, p.label, nil),
			Value:    values[p.name],
			Source:   s.PhraseCtx(ctx, "golem15.seo::lang.effective.source_"+res.Sources[p.name], nil),
			Mono:     p.mono,
		})
	}
	return out
}

// newEffectiveView starts a P2 view with its labels and the staging note.
func (s *Service) newEffectiveView(ctx context.Context) EffectiveView {
	return EffectiveView{
		Staging:       s.Staging(),
		StagingText:   s.PhraseCtx(ctx, "golem15.seo::lang.status.staging", nil),
		PropertyLabel: s.PhraseCtx(ctx, "golem15.seo::lang.effective.property", nil),
		ValueLabel:    s.PhraseCtx(ctx, "golem15.seo::lang.effective.value", nil),
		SourceLabel:   s.PhraseCtx(ctx, "golem15.seo::lang.effective.source", nil),
	}
}

// RecordEffective builds P2 for a record: one table per locale at the
// record's own address, or the no-address line.
func (s *Service) RecordEffective(ctx context.Context, key, id string) (EffectiveView, error) {
	view := s.newEffectiveView(ctx)
	db, err := s.DB(ctx)
	if err != nil {
		return view, err
	}
	described := s.recordLocales(ctx, key, id)
	for _, locale := range s.Locales(ctx, db) {
		l := described[locale]
		heading := s.PhraseCtx(ctx, "golem15.seo::lang.effective.locale", map[string]string{"locale": strings.ToUpper(locale), "url": l.URL})
		res, ok, err := s.Resolver().ResolveRecord(ctx, key, id, locale)
		if err != nil {
			return view, err
		}
		if !ok {
			view.Locales = append(view.Locales, EffectiveLocale{Heading: strings.ToUpper(locale), NoURL: true, NoURLText: s.PhraseCtx(ctx, "golem15.seo::lang.effective.no_url", nil)})
			continue
		}
		view.Locales = append(view.Locales, EffectiveLocale{Heading: heading, Rows: s.EffectiveRows(ctx, res)})
	}
	return view, nil
}

// ruleProperties returns the translated labels of the properties a rule
// sets.
func (s *Service) ruleProperties(ctx context.Context, r models.Rule) []string {
	var out []string
	for _, p := range models.RuleProperties {
		if strings.TrimSpace(r.Value(p.Column)) != "" {
			out = append(out, s.PhraseCtx(ctx, p.Label, nil))
		}
	}
	return out
}

// RecordStatus builds P1 for a record: the URL rule that overrides part of
// its SEO tab (the first one found over its locales), and a canonical that
// points to a page served noindex (D-06).
func (s *Service) RecordStatus(ctx context.Context, key, id string) (StatusView, error) {
	var view StatusView
	db, err := s.DB(ctx)
	if err != nil {
		return view, err
	}
	for _, l := range s.recordLocales(ctx, key, id) {
		if l.URL == "" {
			continue
		}
		path, _, err := parseTarget(l.URL)
		if err != nil {
			continue
		}
		rules, err := matchingRules(db, path, rawQueryOf(l.URL))
		if err != nil {
			return view, err
		}
		if c, ok := s.ruleCallout(ctx, rules); ok {
			view.Callouts = append(view.Callouts, c)
			break
		}
	}
	reg := s.Registry()
	if reg != nil {
		if typ, ok := reg.ContentType(key); ok && typ.Content != nil {
			entries, err := LoadEntries(db, typ.Content.Model, id)
			if err != nil {
				return view, err
			}
			for _, e := range entries {
				if c, ok := s.canonicalCallout(ctx, e.Canonical); ok {
					view.Callouts = append(view.Callouts, c)
					break
				}
			}
		}
	}
	exclusions, err := s.RecordSitemapExclusions(ctx, key, id)
	if err != nil {
		return view, err
	}
	for _, x := range exclusions {
		key, ok := excludedTexts[x.Reason]
		if !ok {
			continue
		}
		view.Callouts = append(view.Callouts, Callout{
			Title: s.PhraseCtx(ctx, "golem15.seo::lang.status.excluded_title", nil),
			Text:  s.PhraseCtx(ctx, key, map[string]string{"url": x.Target}),
			Plain: true,
		})
	}
	return view, nil
}

// excludedTexts are the P1 texts of the sitemap exclusion reasons (UI-SPEC
// C16).
var excludedTexts = map[string]string{
	contract.ReasonNoindex:   "golem15.seo::lang.status.excluded_noindex",
	contract.ReasonCanonical: "golem15.seo::lang.status.excluded_canonical",
	contract.ReasonRedirect:  "golem15.seo::lang.status.excluded_redirect",
	contract.ReasonType:      "golem15.seo::lang.status.excluded_type",
}

// ruleCallout is the override callout of the first rule that sets a value.
func (s *Service) ruleCallout(ctx context.Context, rules []models.Rule) (Callout, bool) {
	for _, r := range rules {
		props := s.ruleProperties(ctx, r)
		if len(props) == 0 {
			continue
		}
		return Callout{
			Title: s.PhraseCtx(ctx, "golem15.seo::lang.status.rule_title", nil),
			Text:  s.PhraseCtx(ctx, "golem15.seo::lang.status.rule_text", map[string]string{"url": r.URL, "fields": strings.Join(props, ", ")}),
		}, true
	}
	return Callout{}, false
}

// canonicalCallout warns about a canonical on this site (D-06): one that
// redirects (status.canonical_redirected, naming the final address), or
// one that resolves to a page served noindex (status.canonical_noindex).
// Outside production every page is noindex, so only the redirect warning
// applies there.
func (s *Service) canonicalCallout(ctx context.Context, canonical string) (Callout, bool) {
	canonical = strings.TrimSpace(canonical)
	if canonical == "" {
		return Callout{}, false
	}
	target := canonical
	if u, err := url.Parse(canonical); err == nil && u.IsAbs() {
		if !sameSite(s.SiteURL(), u.Host) {
			return Callout{}, false
		}
		target = u.String()
	}
	res, err := s.Resolver().Resolve(ctx, target)
	if err != nil {
		return Callout{}, false
	}
	if res.Action == ActionRedirect {
		return Callout{Title: s.PhraseCtx(ctx, "golem15.seo::lang.status.canonical_redirected", map[string]string{"url": canonical, "target": res.Location})}, true
	}
	if s.Staging() || res.SEO == nil || !strings.Contains(res.SEO.Robots, "noindex") {
		return Callout{}, false
	}
	return Callout{Title: s.PhraseCtx(ctx, "golem15.seo::lang.status.canonical_noindex", map[string]string{"url": canonical})}, true
}

// RuleStatus builds P1 for a URL rule: the canonical warning.
func (s *Service) RuleStatus(ctx context.Context, r models.Rule) StatusView {
	var view StatusView
	if c, ok := s.canonicalCallout(ctx, r.Canonical); ok {
		view.Callouts = append(view.Callouts, c)
	}
	return view
}

// RuleEffective builds P2 for a URL rule: an exact rule is resolved at its
// address; a pattern rule shows its own values with the source URL rule.
func (s *Service) RuleEffective(ctx context.Context, r models.Rule) (EffectiveView, error) {
	view := s.newEffectiveView(ctx)
	if r.Match == models.MatchExact {
		res, err := s.Resolver().Resolve(ctx, r.URL)
		if err != nil {
			return view, err
		}
		view.Locales = append(view.Locales, EffectiveLocale{Heading: r.URL, Rows: s.EffectiveRows(ctx, res)})
		return view, nil
	}
	source := s.PhraseCtx(ctx, "golem15.seo::lang.effective.source_rule", nil)
	var rows []EffectiveRow
	for _, p := range effectiveProperties {
		if v := strings.TrimSpace(r.Value(p.name)); v != "" {
			rows = append(rows, EffectiveRow{Property: s.PhraseCtx(ctx, p.label, nil), Value: v, Source: source, Mono: p.mono})
		}
	}
	view.Locales = append(view.Locales, EffectiveLocale{Heading: r.URL, Rows: rows})
	return view, nil
}

// Placeholders builds P3.
func (s *Service) Placeholders(ctx context.Context) PlaceholdersView {
	return PlaceholdersView{
		Caption:      s.PhraseCtx(ctx, "golem15.seo::lang.settings.placeholders", nil),
		CodeLabel:    s.PhraseCtx(ctx, "golem15.seo::lang.settings.placeholders_code", nil),
		MeaningLabel: s.PhraseCtx(ctx, "golem15.seo::lang.settings.placeholders_meaning", nil),
		Rows: []PlaceholderRow{
			{Code: PlaceholderTitle, Meaning: s.PhraseCtx(ctx, "golem15.seo::lang.placeholder.title", nil)},
			{Code: PlaceholderDescription, Meaning: s.PhraseCtx(ctx, "golem15.seo::lang.placeholder.description", nil)},
			{Code: PlaceholderSite, Meaning: s.PhraseCtx(ctx, "golem15.seo::lang.placeholder.site", nil)},
		},
	}
}

// RecordKey returns the primary key of a GORM model as text.
func RecordKey(db *gorm.DB, record any) (string, error) {
	if record == nil || db == nil {
		return "", fmt.Errorf("golem15.seo: no record")
	}
	stmt := &gorm.Statement{DB: db}
	if err := stmt.Parse(record); err != nil {
		return "", err
	}
	if stmt.Schema == nil || stmt.Schema.PrioritizedPrimaryField == nil {
		return "", fmt.Errorf("golem15.seo: %T has no primary key", record)
	}
	v, zero := stmt.Schema.PrioritizedPrimaryField.ValueOf(context.Background(), reflectValue(record))
	if zero {
		return "", fmt.Errorf("golem15.seo: %T has an empty primary key", record)
	}
	return fmt.Sprint(v), nil
}

// reflectValue is the addressable value of a model pointer.
func reflectValue(record any) reflect.Value {
	return reflect.Indirect(reflect.ValueOf(record))
}