package seo

import (
	"context"
	"fmt"
	"strconv"
	"strings"

	"git.golem15.com/golem15/sm-seo-plugin/classes"
	"git.golem15.com/golem15/sm-seo-plugin/controllers"
	"git.golem15.com/golem15/sm-seo-plugin/models"
	"git.golem15.com/golem15/summercms/modules/pact"
	"git.golem15.com/golem15/summercms/modules/signpost"
)

// TabSEO is the key of the SEO tab added to every content type's form.
const TabSEO = "golem15.seo::lang.tab.seo"

// AdminActionExtensions adds the SEO tab (D-01, D-91) to the admin form of
// every content type registered in signpost with a content descriptor that
// names a controller. The content plugins import nothing from this plugin.
func (p *Plugin) AdminActionExtensions() []pact.AdminActionExtension {
	reg := p.registry()
	if reg == nil {
		return nil
	}
	// The Pages form's address and name come first: the SEO tab of a
	// registry page (added below, the registry being a content type) reads
	// the address its save wrote.
	out := []pact.AdminActionExtension{{Controller: controllers.PagesControllerID, Form: p.pagesForm()}}
	types := reg.ContentTypes()
	for _, typ := range types {
		if typ.Content == nil || strings.TrimSpace(typ.Content.Controller) == "" {
			continue
		}
		out = append(out, pact.AdminActionExtension{
			Controller: typ.Content.Controller,
			Form:       p.seoTab(typ.Key, typ.Content.Kind),
		})
	}
	if form := p.typeSettingsTabs(types); form != nil {
		out = append(out, pact.AdminActionExtension{Controller: controllers.SettingsControllerID, Form: form})
	}
	out = append(out, pact.AdminActionExtension{Controller: controllers.RulesControllerID, Form: p.ruleHistory()})
	out = append(out, pact.AdminActionExtension{Controller: controllers.RedirectsControllerID, Form: p.redirectChecks()})
	out = append(out, pact.AdminActionExtension{Controller: controllers.AutolinksControllerID, Form: p.autolinkHistory()})
	out = append(out, pact.AdminActionExtension{Controller: controllers.RobotsControllerID, Form: p.robotsForm()})
	return out
}

// redirectChecks is a field-less extension on the plugin's own redirects
// controller (P-18). Its Save runs inside the save transaction with the
// row written: it simulates the rule in place, refuses a loop with
// redirects.loop on target (D-19, the save rolls back), answers a chain
// with redirects.chain_notice on target, and records the save in history.
func (p *Plugin) redirectChecks() *pact.AdminFormExtension {
	return &pact.AdminFormExtension{
		Permissions: []string{controllers.PermissionManage},
		Save: func(ctx context.Context, in pact.AdminFormSave) (pact.AdminFormSaveResult, error) {
			svc := p.Service()
			if svc == nil {
				return pact.AdminFormSaveResult{}, classes.ErrNotBooted
			}
			r, ok := in.Record.(*models.Redirect)
			if !ok || r == nil {
				return pact.AdminFormSaveResult{}, nil
			}
			check, err := svc.CheckRedirect(ctx, in.DB, *r)
			if err != nil {
				return pact.AdminFormSaveResult{}, err
			}
			if check.Loop {
				return pact.AdminFormSaveResult{}, pact.AdminFormErrors{"target": {svc.LoopMessage(ctx, check)}}
			}
			before, after := classes.ChangesValues(in.Changes, in.Created)
			if err := svc.Record(ctx, in.DB, classes.Change{
				Kind:      models.SubjectRedirect,
				SubjectID: in.ID,
				What:      svc.Phrase("golem15.seo::lang.history.what_redirect", map[string]string{"url": r.Source}),
				Before:    before,
				After:     after,
			}); err != nil {
				return pact.AdminFormSaveResult{}, err
			}
			if notices := classes.ChainNotice(check); len(notices) > 0 {
				return pact.AdminFormSaveResult{Notices: map[string][]pact.FormFieldNotice{"target": notices}}, nil
			}
			return pact.AdminFormSaveResult{}, nil
		},
	}
}

// ruleHistory is a field-less extension on the plugin's own rules
// controller: its Save sees the save's changes inside the save transaction
// and records them in history (deletes are recorded by the controller).
func (p *Plugin) ruleHistory() *pact.AdminFormExtension {
	return &pact.AdminFormExtension{
		Permissions: []string{controllers.PermissionManage},
		Save: func(ctx context.Context, in pact.AdminFormSave) (pact.AdminFormSaveResult, error) {
			svc := p.Service()
			if svc == nil {
				return pact.AdminFormSaveResult{}, classes.ErrNotBooted
			}
			before, after := classes.ChangesValues(in.Changes, in.Created)
			url := ""
			if r, ok := in.Record.(*models.Rule); ok && r != nil {
				url = r.URL
			}
			return pact.AdminFormSaveResult{}, svc.Record(ctx, in.DB, classes.Change{
				Kind:      models.SubjectRule,
				SubjectID: in.ID,
				What:      svc.Phrase("golem15.seo::lang.history.what_rule", map[string]string{"url": url}),
				Before:    before,
				After:     after,
			})
		},
	}
}

// autolinkHistory is a field-less extension on the plugin's own Auto-links
// controller: its Save sees the save's changes inside the save
// transaction and records them in history, which purges the site's cached
// pages (deletes are recorded by the controller).
func (p *Plugin) autolinkHistory() *pact.AdminFormExtension {
	return &pact.AdminFormExtension{
		Permissions: []string{controllers.PermissionManage},
		Save: func(ctx context.Context, in pact.AdminFormSave) (pact.AdminFormSaveResult, error) {
			svc := p.Service()
			if svc == nil {
				return pact.AdminFormSaveResult{}, classes.ErrNotBooted
			}
			a, ok := in.Record.(*models.Autolink)
			if !ok || a == nil {
				return pact.AdminFormSaveResult{}, nil
			}
			before, after := classes.ChangesValues(in.Changes, in.Created)
			return pact.AdminFormSaveResult{}, svc.Record(ctx, in.DB, classes.Change{
				Kind:      models.SubjectAutolink,
				SubjectID: in.ID,
				What:      svc.Phrase("golem15.seo::lang.history.what_autolink", map[string]string{"phrase": a.Phrase}),
				Before:    before,
				After:     after,
			})
		},
	}
}

func (p *Plugin) registry() *signpost.Registry {
	if p == nil || p.app == nil {
		return nil
	}
	reg, _ := p.app.Lookup[*signpost.Registry]()
	return reg
}

// seoTabYAML is the SEO tab's fields document (UI-SPEC C3): the tab placed
// after the owner's tabs (no anchor, P-17) and its fields in order. The
// names seo_robots and seo_og_image are anchors Phase 33 places fields
// after; they must not be renamed.
const seoTabYAML = `tabs:
    - name: golem15.seo::lang.tab.seo
fields:
    seo_status:
        type: partial
        path: seo_status
        span: full
        context: update
        tab: golem15.seo::lang.tab.seo
    seo_snippet:
        label: golem15.seo::lang.field.snippet
        type: widget
        widget: golem15-seo-serp
        action: seo_snippet
        fill: [seo_title, seo_description, seo_keyphrase]
        span: full
        context: [create, update]
        tab: golem15.seo::lang.tab.seo
    seo_title:
        label: golem15.seo::lang.field.title
        comment: golem15.seo::lang.field.title_comment
        type: mlseotext
        measure: title
        span: full
        tab: golem15.seo::lang.tab.seo
    seo_description:
        label: golem15.seo::lang.field.description
        comment: golem15.seo::lang.field.description_comment
        type: mlseotext
        measure: description
        span: full
        tab: golem15.seo::lang.tab.seo
    seo_keyphrase:
        label: golem15.seo::lang.field.keyphrase
        comment: golem15.seo::lang.field.keyphrase_comment
        type: mltext
        span: left
        tab: golem15.seo::lang.tab.seo
    seo_canonical:
        label: golem15.seo::lang.field.canonical
        comment: golem15.seo::lang.field.canonical_comment
        type: mltext
        span: right
        tab: golem15.seo::lang.tab.seo
    seo_robots:
        label: golem15.seo::lang.field.robots
        comment: golem15.seo::lang.field.robots_comment
        type: mlseorobots
        scope: record
        span: full
        tab: golem15.seo::lang.tab.seo
    seo_og_title:
        label: golem15.seo::lang.field.og_title
        comment: golem15.seo::lang.field.og_title_comment
        type: mltext
        span: full
        tab: golem15.seo::lang.tab.seo
    seo_og_description:
        label: golem15.seo::lang.field.og_description
        type: mltextarea
        size: small
        span: full
        tab: golem15.seo::lang.tab.seo
    seo_og_image:
        label: golem15.seo::lang.field.og_image
        comment: golem15.seo::lang.field.og_image_comment
        type: seoimage
        span: full
        tab: golem15.seo::lang.tab.seo
    seo_effective:
        label: golem15.seo::lang.field.effective
        type: partial
        path: seo_effective
        span: full
        context: update
        tab: golem15.seo::lang.tab.seo
`

// seoTabFor is the SEO tab's fields document of a content type (UI-SPEC
// C16): seoTabYAML with the primary category after seo_robots for article
// types (whose records have parents, P33-23), and the structured data
// field (E8) and its preview (E9) after seo_og_image.
func seoTabFor(key, kind string) string {
	doc := seoTabYAML
	quoted := strconv.Quote(key)
	if kind == pact.ContentKindArticle {
		doc = strings.Replace(doc, "    seo_og_title:\n", `    seo_primary_parent:
        label: golem15.seo::lang.field.primary_category
        comment: golem15.seo::lang.field.primary_category_comment
        type: seoparent
        contentType: `+quoted+`
        span: full
        context: [create, update]
        tab: golem15.seo::lang.tab.seo
    seo_og_title:
`, 1)
	}
	return strings.Replace(doc, "    seo_effective:\n", `    seo_schema:
        label: golem15.seo::lang.field.schema
        comment: golem15.seo::lang.field.schema_comment
        type: seoschema
        kind: `+strconv.Quote(kind)+`
        contentType: `+quoted+`
        span: full
        context: [create, update]
        tab: golem15.seo::lang.tab.seo
    seo_graph:
        label: golem15.seo::lang.field.graph
        type: widget
        widget: golem15-seo-graph
        action: seo_graph
        fill: [seo_schema]
        span: full
        context: update
        tab: golem15.seo::lang.tab.seo
    seo_effective:
`, 1)
}

// seoTab is the form extension of content type key of kind.
func (p *Plugin) seoTab(key, kind string) *pact.AdminFormExtension {
	return &pact.AdminFormExtension{
		FieldsYAML:  []byte(seoTabFor(key, kind)),
		Permissions: []string{controllers.PermissionManage},
		Visible: func(ctx context.Context) bool {
			return p.injected(ctx, key)
		},
		Dir: "extension",
		Actions: []pact.AdminAction{
			classes.RecordSnippetAction(p.Service, key, "golem15.seo::lang.snippet.action", controllers.PermissionManage),
			classes.RecordGraphAction(p.Service, key, "golem15.seo::lang.graph.action", controllers.PermissionManage),
		},
		PartialData: func(ctx context.Context, name string, record any) (any, error) {
			return p.seoTabPartial(ctx, key, name, record)
		},
		Load: func(ctx context.Context, in pact.AdminFormLoad) (map[string]any, error) {
			return p.loadSEOTab(ctx, key, in)
		},
		Save: func(ctx context.Context, in pact.AdminFormSave) (pact.AdminFormSaveResult, error) {
			return p.saveSEOTab(ctx, key, in)
		},
	}
}

// seoTabPartial serves P1 seo_status and P2 seo_effective of a record.
func (p *Plugin) seoTabPartial(ctx context.Context, key, name string, record any) (any, error) {
	svc := p.Service()
	if svc == nil {
		return nil, classes.ErrNotBooted
	}
	db, err := svc.DB(ctx)
	if err != nil {
		return nil, err
	}
	id, err := classes.RecordKey(db, record)
	if err != nil {
		if name == "seo_effective" {
			return classes.EffectiveView{}, nil
		}
		return classes.StatusView{}, nil
	}
	switch name {
	case "seo_status":
		return svc.RecordStatus(ctx, key, id)
	case "seo_effective":
		return svc.RecordEffective(ctx, key, id)
	}
	return nil, nil
}

// contentType returns the registered content type key with a descriptor.
func (p *Plugin) contentType(key string) (pact.MenuItemType, error) {
	reg := p.registry()
	if reg == nil {
		return pact.MenuItemType{}, fmt.Errorf("golem15.seo: menu item type registry is not published")
	}
	typ, ok := reg.ContentType(key)
	if !ok {
		return pact.MenuItemType{}, fmt.Errorf("golem15.seo: content type %q is not registered", key)
	}
	return typ, nil
}

// loadSEOTab returns the stored SEO tab values of a record, every field a
// map of locale to text.
func (p *Plugin) loadSEOTab(ctx context.Context, key string, in pact.AdminFormLoad) (map[string]any, error) {
	svc := p.Service()
	if svc == nil {
		return nil, classes.ErrNotBooted
	}
	typ, err := p.contentType(key)
	if err != nil {
		return nil, err
	}
	entries, err := classes.LoadEntries(in.DB.WithContext(ctx), typ.Content.Model, in.ID)
	if err != nil {
		return nil, err
	}
	out := map[string]any{}
	for column, perLocale := range classes.RecordValuesOf(entries) {
		if column == classes.SharedColumn {
			out[classes.FieldPrefix+column] = classes.SharedValue(entries)
			continue
		}
		out[classes.FieldPrefix+column] = perLocale
	}
	out[classes.FieldPrefix+classes.DataSchema] = classes.SharedData(entries, classes.DataSchema)
	if typ.Content.Kind == pact.ContentKindArticle {
		out[classes.FieldPrefix+classes.DataPrimaryParent] = map[string]any{
			"selected": classes.SharedData(entries, classes.DataPrimaryParent),
			"options":  svc.ParentOptions(ctx, key, in.ID, ""),
		}
	}
	return out, nil
}

// saveSEOTab stores the submitted SEO tab values of a record inside the
// record's save transaction. On an update it first compares the record's
// addresses with its entries' URLs and creates the 301 of a changed
// address (AddressChanged), answered as the redirects.auto_created notice.
func (p *Plugin) saveSEOTab(ctx context.Context, key string, in pact.AdminFormSave) (pact.AdminFormSaveResult, error) {
	svc := p.Service()
	if svc == nil {
		return pact.AdminFormSaveResult{}, classes.ErrNotBooted
	}
	typ, err := p.contentType(key)
	if err != nil {
		return pact.AdminFormSaveResult{}, err
	}
	values := classes.RecordValues{}
	refusals := pact.AdminFormErrors{}
	for _, column := range append(append([]string{}, classes.EntryColumns...), classes.DataColumns...) {
		raw, ok := in.Values[classes.FieldPrefix+column]
		if !ok {
			continue
		}
		perLocale := localeMap(raw)
		if column == "canonical" {
			for _, v := range perLocale {
				if v = strings.TrimSpace(v); v != "" && !classes.ValidURLRef(v) {
					refusals[classes.FieldPrefix+column] = []string{svc.PhraseCtx(ctx, "lagoon::validation.url", map[string]string{
						"attribute": svc.PhraseCtx(ctx, "golem15.seo::lang.field.canonical", nil),
					})}
					break
				}
			}
		}
		values[column] = perLocale
	}
	if len(refusals) > 0 {
		return pact.AdminFormSaveResult{}, refusals
	}
	// The address diff runs before the values are written, because the
	// write refreshes the entries' URLs (D-18, P-20).
	var moved []classes.AddressResult
	if !in.Created {
		changes, err := svc.AddressChanges(ctx, in.DB, typ, in.ID)
		if err != nil {
			return pact.AdminFormSaveResult{}, err
		}
		for _, change := range changes {
			res, err := svc.AddressChanged(ctx, in.DB, change)
			if err != nil {
				return pact.AdminFormSaveResult{}, err
			}
			if res.Redirect != nil {
				moved = append(moved, res)
			}
		}
	}
	if _, _, err := svc.SaveRecord(ctx, in.DB, classes.RecordWrite{Type: typ, ID: in.ID, Values: values}); err != nil {
		return pact.AdminFormSaveResult{}, err
	}
	notices := classes.AddressNotices(typ, in.Changes, moved, "seo_status")
	if _, sent := values[classes.DataSchema]; sent {
		merged, err := svc.SchemaMerges(ctx, key, in.ID)
		if err != nil {
			return pact.AdminFormSaveResult{}, err
		}
		if len(merged) > 0 {
			if notices == nil {
				notices = map[string][]pact.FormFieldNotice{}
			}
			field := classes.FieldPrefix + classes.DataSchema
			notices[field] = append(notices[field], merged...)
		}
	}
	return pact.AdminFormSaveResult{Notices: notices}, nil
}

// localeMap reads a submitted value as locale -> text: a translatable
// field's map, or a plain string under the empty locale key.
func localeMap(raw any) map[string]string {
	switch v := raw.(type) {
	case map[string]string:
		return v
	case map[string]any:
		out := make(map[string]string, len(v))
		for locale, value := range v {
			if s, ok := value.(string); ok {
				out[locale] = s
			}
		}
		return out
	case string:
		return map[string]string{"": v}
	}
	return map[string]string{}
}

// injected reports whether the SEO tab of content type key is shown: false
// only when its settings row turns it off. It answers true when it cannot
// decide, so a database error never hides stored values.
func (p *Plugin) injected(ctx context.Context, key string) bool {
	svc := p.Service()
	if svc == nil {
		return true
	}
	db, err := svc.DB(ctx)
	if err != nil {
		return true
	}
	row, err := classes.LoadTypeSetting(db, key)
	if err != nil {
		return true
	}
	return row.Inject
}