package classes

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
	"time"

	"git.golem15.com/golem15/sm-seo-plugin/models"
	"git.golem15.com/golem15/summercms/modules/lagoon"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

// SettingsRow returns settings row 1 inside db, creating it with the
// defaults when the migration's row is gone.
func SettingsRow(db *gorm.DB) (models.Settings, error) {
	var rows []models.Settings
	if err := db.Where("id = ?", 1).Limit(1).Find(&rows).Error; err != nil {
		return models.Settings{}, err
	}
	if len(rows) > 0 {
		return rows[0], nil
	}
	row := models.DefaultSettings()
	if err := db.Clauses(clause.OnConflict{DoNothing: true}).Create(&row).Error; err != nil {
		return models.Settings{}, err
	}
	return LoadSettings(db)
}

// SettingsColumns are the settings columns the API reads and writes, in
// form order: the admin form's columns and the CSV delimiter of the
// import and export screen.
var SettingsColumns = []string{
	"site_name", "twitter_site", "title_template", "home_template",
	"default_description", "default_og_image", "query_params",
	"noindex_paths", "search_paths", "url_host", "url_slash",
	"url_lowercase", "verify_google", "verify_bing", "verify_yandex",
	"verify_other", "verify_files", "csv_delimiter",
}

// SettingsValues are the settings row's values keyed by column, for
// history and the API.
func SettingsValues(st models.Settings) map[string]any {
	return map[string]any{
		"site_name":           st.SiteName,
		"twitter_site":        st.TwitterSite,
		"title_template":      st.TitleTemplate,
		"home_template":       st.HomeTemplate,
		"default_description": st.DefaultDescription,
		"default_og_image":    st.DefaultOGImage,
		"query_params":        plainValue(st.Params()),
		"noindex_paths":       st.NoindexPaths,
		"search_paths":        st.SearchPaths,
		"url_host":            st.URLHost,
		"url_slash":           st.URLSlash,
		"url_lowercase":       st.URLLowercase,
		"verify_google":       st.VerifyGoogle,
		"verify_bing":         st.VerifyBing,
		"verify_yandex":       st.VerifyYandex,
		"verify_other":        plainValue(st.OtherMeta()),
		"verify_files":        plainValue(st.Files()),
		"csv_delimiter":       st.CSVDelimiter,
	}
}

// SetSettingsValue writes one column of the settings from a JSON value
// (a string, a bool, or a list of objects); an unknown column or a value
// of the wrong shape is an error.
func SetSettingsValue(st *models.Settings, column string, v any) error {
	text := func() (string, error) {
		switch s := v.(type) {
		case string:
			return s, nil
		case nil:
			return "", nil
		}
		return "", fmt.Errorf("golem15.seo: settings %s is not text", column)
	}
	list := func(dst any) error {
		raw, err := json.Marshal(v)
		if err != nil {
			return err
		}
		if string(raw) == "null" {
			raw = []byte("[]")
		}
		return json.Unmarshal(raw, dst)
	}
	var err error
	switch column {
	case "site_name":
		st.SiteName, err = text()
	case "twitter_site":
		st.TwitterSite, err = text()
	case "title_template":
		st.TitleTemplate, err = text()
	case "home_template":
		st.HomeTemplate, err = text()
	case "default_description":
		st.DefaultDescription, err = text()
	case "default_og_image":
		st.DefaultOGImage, err = text()
	case "noindex_paths":
		st.NoindexPaths, err = text()
	case "search_paths":
		st.SearchPaths, err = text()
	case "url_host":
		st.URLHost, err = text()
	case "url_slash":
		st.URLSlash, err = text()
	case "verify_google":
		st.VerifyGoogle, err = text()
	case "verify_bing":
		st.VerifyBing, err = text()
	case "verify_yandex":
		st.VerifyYandex, err = text()
	case "csv_delimiter":
		st.CSVDelimiter, err = text()
	case "url_lowercase":
		b, ok := v.(bool)
		if !ok {
			return fmt.Errorf("golem15.seo: settings %s is not a bool", column)
		}
		st.URLLowercase = b
	case "query_params":
		var out []models.QueryParam
		if err = list(&out); err == nil {
			st.QueryParams = lagoon.Jsonable[[]models.QueryParam]{Data: out, Valid: true}
		}
	case "verify_other":
		var out []models.VerifyMeta
		if err = list(&out); err == nil {
			st.VerifyOther = lagoon.Jsonable[[]models.VerifyMeta]{Data: out, Valid: true}
		}
	case "verify_files":
		var out []models.VerifyFile
		if err = list(&out); err == nil {
			st.VerifyFiles = lagoon.Jsonable[[]models.VerifyFile]{Data: out, Valid: true}
		}
	default:
		return fmt.Errorf("golem15.seo: unknown settings column %q", column)
	}
	return err
}

// TypeSettingWrite changes the settings of one content type: a nil field
// is left as it is.
type TypeSettingWrite struct {
	Inject              *bool   `json:"inject,omitempty"`
	TitleTemplate       *string `json:"title_template,omitempty"`
	DescriptionTemplate *string `json:"description_template,omitempty"`
	Robots              *string `json:"robots,omitempty"`
}

// SettingsWrite is one change of the SEO settings: Values are columns of
// SettingsColumns with JSON values, Types per content type key.
type SettingsWrite struct {
	Values map[string]any
	Types  map[string]TypeSettingWrite
}

// SaveSettings writes the settings inside tx and records them in history,
// like the settings screen (D-104): templates with an unknown placeholder,
// malformed or duplicate verification files, an unknown address option or
// delimiter, robots values outside the grammar and unknown content types
// are refused with a *ProblemsError. Once the write commits, the entry
// generation job is queued so the effective-value cache follows.
func (s *Service) SaveSettings(ctx context.Context, tx *gorm.DB, in SettingsWrite) (models.Settings, error) {
	row, err := SettingsRow(tx)
	if err != nil {
		return models.Settings{}, err
	}
	before := SettingsValues(row)
	problems := map[string][]models.Problem{}
	known := map[string]bool{}
	for _, c := range SettingsColumns {
		known[c] = true
	}
	for column, v := range in.Values {
		if !known[column] {
			problems[column] = append(problems[column], models.Problem{Key: "golem15.seo::lang.api.field_unknown"})
			continue
		}
		if s, ok := v.(string); ok {
			v = strings.TrimSpace(s)
		}
		if err := SetSettingsValue(&row, column, v); err != nil {
			problems[column] = append(problems[column], models.Problem{Key: "golem15.seo::lang.api.value_invalid"})
		}
	}
	oneOf := func(column, value string, allowed ...string) {
		for _, a := range allowed {
			if value == a {
				return
			}
		}
		problems[column] = append(problems[column], models.Problem{Key: "golem15.seo::lang.api.value_invalid"})
	}
	oneOf("url_host", row.URLHost, models.HostKeep, models.HostWWW, models.HostBare)
	oneOf("url_slash", row.URLSlash, models.SlashKeep, models.SlashAdd, models.SlashDrop)
	oneOf("csv_delimiter", row.CSVDelimiter, "", ",", ";")
	for field, list := range row.Problems() {
		problems[field] = append(problems[field], list...)
	}
	types, err := LoadTypeSettings(tx)
	if err != nil {
		return models.Settings{}, err
	}
	changed := map[string]models.TypeSetting{}
	reg := s.Registry()
	for key, w := range in.Types {
		field := "types." + key
		if reg == nil {
			problems[field] = append(problems[field], models.Problem{Key: "golem15.seo::lang.api.type_unknown"})
			continue
		}
		if _, ok := reg.ContentType(key); !ok {
			problems[field] = append(problems[field], models.Problem{Key: "golem15.seo::lang.api.type_unknown"})
			continue
		}
		ts, ok := types[key]
		if !ok {
			ts = models.DefaultTypeSetting(key)
		}
		if w.Inject != nil {
			ts.Inject = *w.Inject
		}
		if w.TitleTemplate != nil {
			ts.TitleTemplate = strings.TrimSpace(*w.TitleTemplate)
			problems[field+".title_template"] = append(problems[field+".title_template"], models.TemplateProblems(ts.TitleTemplate)...)
		}
		if w.DescriptionTemplate != nil {
			ts.DescriptionTemplate = strings.TrimSpace(*w.DescriptionTemplate)
			problems[field+".description_template"] = append(problems[field+".description_template"], models.TemplateProblems(ts.DescriptionTemplate)...)
		}
		if w.Robots != nil {
			normal, err := NormalizeRobots(*w.Robots)
			if err != nil {
				problems[field+".robots"] = append(problems[field+".robots"], models.Problem{Key: "golem15.seo::lang.robots.invalid"})
			}
			ts.Robots = normal
		}
		changed[key] = ts
	}
	for field, list := range problems {
		if len(list) == 0 {
			delete(problems, field)
		}
	}
	if len(problems) > 0 {
		return models.Settings{}, &ProblemsError{Problems: problems}
	}
	now := time.Now().UTC()
	row.UpdatedAt = &now
	if err := tx.Save(&row).Error; err != nil {
		return models.Settings{}, err
	}
	if err := s.Record(ctx, tx, Change{
		Kind:      models.SubjectSettings,
		SubjectID: "1",
		What:      s.Phrase("golem15.seo::lang.history.what_settings", nil),
		Before:    before,
		After:     SettingsValues(row),
	}); err != nil {
		return models.Settings{}, err
	}
	for key, ts := range changed {
		old, ok := types[key]
		if !ok {
			old = models.DefaultTypeSetting(key)
		}
		if err := s.SaveTypeSetting(ctx, tx, ts); err != nil {
			return models.Settings{}, err
		}
		label := key
		if typ, ok := reg.ContentType(key); ok && typ.Label != "" {
			label = s.Phrase(typ.Label, nil)
		}
		if err := s.Record(ctx, tx, Change{
			Kind:      models.SubjectSettings,
			SubjectID: "type:" + key,
			What:      s.Phrase("golem15.seo::lang.history.what_settings", nil) + " – " + label,
			Before:    TypeSettingValues(old),
			After:     TypeSettingValues(ts),
		}); err != nil {
			return models.Settings{}, err
		}
	}
	s.queueGenerateAfterCommit(ctx, tx)
	return row, nil
}

// queueGenerateAfterCommit queues the entry generation job once tx
// commits; a queue error is logged.
func (s *Service) queueGenerateAfterCommit(ctx context.Context, tx *gorm.DB) {
	lagoon.AfterCommit(ctx, tx, func(ctx context.Context, _ *gorm.DB) {
		db, err := s.GormDB()
		if err != nil {
			return
		}
		if _, err := s.EnqueueGenerate(ctx, db.WithContext(ctx), ""); err != nil {
			log.Warn("golem15.seo: queue entry generation", "error", err)
		}
	})
}