package catalog

import (
	"context"

	"github.com/descrybe/descrybe-v2/apps/api/internal/aiprompts"
	"github.com/descrybe/descrybe-v2/apps/api/internal/company"
	"github.com/google/uuid"
	"github.com/jackc/pgx/v5/pgconn"
)

// DefaultFormulaTarget is one freshly created category to seed formulas onto.
type DefaultFormulaTarget struct {
	ID       uuid.UUID
	UniqueID string
	Name     string
}

// pgxExecer is the subset of pgxpool.Pool / pgx.Tx used here so the helper works
// inside the CSV import transaction as well as on the plain pool.
type pgxExecer interface {
	Exec(ctx context.Context, sql string, args ...any) (pgconn.CommandTag, error)
}

// applyDefaultCategoryFormulasSQL fills prompt / title_template / description_template
// on newly created categories. Only empty columns are written, so a tenant that
// already authored a formula (or an A1 category carrying its Slovenian legacy
// prompt) is never overwritten.
const applyDefaultCategoryFormulasSQL = `
	UPDATE categories AS c SET
		prompt = CASE
			WHEN c.prompt IS NULL OR c.prompt = '{}'::jsonb
			THEN v.prompt::jsonb ELSE c.prompt END,
		title_template = CASE
			WHEN c.title_template IS NULL OR c.title_template::text IN ('null', '{}')
			THEN NULLIF(v.title_template, '')::jsonb ELSE c.title_template END,
		description_template = CASE
			WHEN c.description_template IS NULL OR c.description_template::text IN ('null', '{}')
			THEN NULLIF(v.description_template, '')::jsonb ELSE c.description_template END,
		updated_at = now()
	FROM (
		SELECT * FROM unnest($2::uuid[], $3::text[], $4::text[], $5::text[])
			AS t(id, prompt, title_template, description_template)
	) AS v
	WHERE c.id = v.id AND c.company_id = $1`

// ApplyDefaultCategoryFormulas gives newly created categories the platform-default
// formulas (English, same style as the A1 legacy templates) when they have none.
//
// New categories get a working title/description/meta formula out of the box
// instead of falling through to generic "1-3 paragraphs" copy. Existing rows are
// untouched — this only runs at create time. A1 categories keep their Slovenian
// prompts because seed-a1 writes them and the SQL never overwrites a set column.
func ApplyDefaultCategoryFormulas(ctx context.Context, db pgxExecer, companyID uuid.UUID, targets ...DefaultFormulaTarget) error {
	if db == nil || len(targets) == 0 {
		return nil
	}
	ids := make([]uuid.UUID, 0, len(targets))
	prompts := make([]string, 0, len(targets))
	titles := make([]string, 0, len(targets))
	descs := make([]string, 0, len(targets))
	for _, t := range targets {
		if t.ID == uuid.Nil {
			continue
		}
		def := aiprompts.DefaultCategoryFormula(t.UniqueID, t.Name)
		if def.Overlay == "" {
			continue
		}
		// "*" applies to every content language: the formula text is English while
		// {{language}} still selects the output language at render time.
		promptJSON, err := company.EncodeLangPromptMap(company.LangPromptMap{"*": def.Overlay})
		if err != nil {
			return err
		}
		ids = append(ids, t.ID)
		prompts = append(prompts, string(promptJSON))
		titles = append(titles, def.TitleTemplateJSON)
		descs = append(descs, def.DescriptionTemplateJSON)
	}
	if len(ids) == 0 {
		return nil
	}
	_, err := db.Exec(ctx, applyDefaultCategoryFormulasSQL, companyID, ids, prompts, titles, descs)
	return err
}