package seo

import (
	"context"
	"fmt"
	"regexp"
	"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/phrasebook"
	"github.com/goccy/go-yaml"
)

// TabGeneral is the settings form's General tab key; the per-type tabs
// follow it.
const TabGeneral = "golem15.seo::lang.settings.tab_general"

// typeFieldKey turns a content type key into the part of a field name:
// every character outside [a-z0-9_] becomes "_".
var typeFieldUnsafe = regexp.MustCompile(`[^a-z0-9_]`)

func typeFieldKey(key string) string {
	return typeFieldUnsafe.ReplaceAllString(strings.ToLower(key), "_")
}

// typeField is one per-type settings field: its name, the content type and
// the type_settings column it edits.
type typeField struct {
	name   string
	key    string
	column string
}

// typeSettingsFields lists the per-type fields of types in form order.
func typeSettingsFields(types []pact.MenuItemType) []typeField {
	var out []typeField
	for _, typ := range types {
		base := "type_" + typeFieldKey(typ.Key) + "_"
		for _, column := range []string{"inject", "title_template", "description_template", "robots"} {
			out = append(out, typeField{name: base + column, key: typ.Key, column: column})
		}
	}
	return out
}

// typeSettingsDocument builds the fields document of the per-type settings
// tabs (D-104): one tab per content type in registration order, the first
// after General and each next after the previous, labelled with the type's
// signpost label.
func typeSettingsDocument(types []pact.MenuItemType) ([]byte, error) {
	type tabSpec struct {
		Name  string `yaml:"name"`
		After string `yaml:"after"`
	}
	tabs := make([]tabSpec, 0, len(types))
	fields := yaml.MapSlice{}
	prev := TabGeneral
	for _, typ := range types {
		tab := typ.Label
		if strings.TrimSpace(tab) == "" {
			tab = typ.Key
		}
		tabs = append(tabs, tabSpec{Name: tab, After: prev})
		prev = tab
		base := "type_" + typeFieldKey(typ.Key) + "_"
		fields = append(fields,
			yaml.MapItem{Key: base + "inject", Value: yaml.MapSlice{
				{Key: "label", Value: "golem15.seo::lang.settings.type_inject"},
				{Key: "comment", Value: "golem15.seo::lang.settings.type_inject_comment"},
				{Key: "type", Value: "switch"},
				{Key: "span", Value: "full"},
				{Key: "tab", Value: tab},
			}},
			yaml.MapItem{Key: base + "title_template", Value: yaml.MapSlice{
				{Key: "label", Value: "golem15.seo::lang.settings.type_title_template"},
				{Key: "comment", Value: "golem15.seo::lang.settings.type_title_template_comment"},
				{Key: "type", Value: "text"},
				{Key: "span", Value: "left"},
				{Key: "tab", Value: tab},
			}},
			yaml.MapItem{Key: base + "description_template", Value: yaml.MapSlice{
				{Key: "label", Value: "golem15.seo::lang.settings.type_description_template"},
				{Key: "type", Value: "text"},
				{Key: "span", Value: "right"},
				{Key: "tab", Value: tab},
			}},
			yaml.MapItem{Key: base + "robots", Value: yaml.MapSlice{
				{Key: "label", Value: "golem15.seo::lang.settings.type_robots"},
				{Key: "type", Value: "dropdown"},
				{Key: "span", Value: "full"},
				{Key: "tab", Value: tab},
				{Key: "options", Value: yaml.MapSlice{
					{Key: "", Value: "golem15.seo::lang.robots.site_default"},
					{Key: "index,follow", Value: "index, follow"},
					{Key: "noindex,follow", Value: "noindex, follow"},
					{Key: "index,nofollow", Value: "index, nofollow"},
					{Key: "noindex,nofollow", Value: "noindex, nofollow"},
				}},
			}},
		)
	}
	return yaml.Marshal(yaml.MapSlice{
		{Key: "tabs", Value: tabs},
		{Key: "fields", Value: fields},
	})
}

// typeSettingsTabs is the form extension on the SEO settings controller
// that adds the per-type tabs; nil when no content type is registered.
func (p *Plugin) typeSettingsTabs(types []pact.MenuItemType) *pact.AdminFormExtension {
	if len(types) == 0 {
		return nil
	}
	doc, err := typeSettingsDocument(types)
	if err != nil {
		pluginLog.Error("golem15.seo: per-type settings tabs", "error", err)
		return nil
	}
	fields := typeSettingsFields(types)
	return &pact.AdminFormExtension{
		FieldsYAML:  doc,
		Permissions: []string{controllers.PermissionManage},
		Load: func(ctx context.Context, in pact.AdminFormLoad) (map[string]any, error) {
			rows, err := classes.LoadTypeSettings(in.DB.WithContext(ctx))
			if err != nil {
				return nil, err
			}
			out := map[string]any{}
			for _, f := range fields {
				row, ok := rows[f.key]
				if !ok {
					row = models.DefaultTypeSetting(f.key)
				}
				out[f.name] = typeSettingValue(row, f.column)
			}
			return out, nil
		},
		Save: func(ctx context.Context, in pact.AdminFormSave) (pact.AdminFormSaveResult, error) {
			return pact.AdminFormSaveResult{}, p.saveTypeSettings(ctx, in, fields)
		},
	}
}

// typeSettingValue reads one column of a type settings row.
func typeSettingValue(row models.TypeSetting, column string) any {
	switch column {
	case "inject":
		return row.Inject
	case "title_template":
		return row.TitleTemplate
	case "description_template":
		return row.DescriptionTemplate
	case "robots":
		return row.Robots
	}
	return nil
}

// saveTypeSettings stores the submitted per-type values through the
// service; a template with an unknown placeholder refuses the save.
func (p *Plugin) saveTypeSettings(ctx context.Context, in pact.AdminFormSave, fields []typeField) error {
	svc := p.Service()
	if svc == nil {
		return classes.ErrNotBooted
	}
	rows, err := classes.LoadTypeSettings(in.DB)
	if err != nil {
		return err
	}
	changed := map[string]models.TypeSetting{}
	refusals := pact.AdminFormErrors{}
	var tr *phrasebook.Translator
	if p.app != nil {
		tr, _ = p.app.Lookup[*phrasebook.Translator]()
	}
	for _, f := range fields {
		raw, ok := in.Values[f.name]
		if !ok {
			continue
		}
		row, seen := changed[f.key]
		if !seen {
			if row, ok = rows[f.key]; !ok {
				row = models.DefaultTypeSetting(f.key)
			}
		}
		switch f.column {
		case "inject":
			row.Inject = truthy(raw)
		case "title_template", "description_template":
			text := strings.TrimSpace(fmt.Sprint(stringOf(raw)))
			for _, problem := range models.TemplateProblems(text) {
				refusals[f.name] = append(refusals[f.name], controllers.Phrase(ctx, tr, problem.Key, problem.Params))
			}
			if f.column == "title_template" {
				row.TitleTemplate = text
			} else {
				row.DescriptionTemplate = text
			}
		case "robots":
			row.Robots = strings.TrimSpace(stringOf(raw))
		}
		changed[f.key] = row
	}
	if len(refusals) > 0 {
		return refusals
	}
	for _, row := range changed {
		if err := svc.SaveTypeSetting(ctx, in.DB, row); err != nil {
			return err
		}
	}
	return nil
}

// truthy reads a submitted switch value.
func truthy(v any) bool {
	switch b := v.(type) {
	case bool:
		return b
	case string:
		return b == "1" || strings.EqualFold(b, "true") || strings.EqualFold(b, "on")
	case fmt.Stringer:
		return b.String() == "1"
	}
	return false
}

// stringOf reads a submitted text value.
func stringOf(v any) string {
	switch s := v.(type) {
	case string:
		return s
	case nil:
		return ""
	}
	return fmt.Sprint(v)
}