package company

import (
	"context"
	"fmt"
	"strings"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5/pgxpool"
)

// DefaultLanguage is the content-language fallback when unset.
const DefaultLanguage = "en"

// ContentLanguages is the allowlist for companies.language (AI/product content).
// Keep in sync with apps/web/src/lib/content-languages.ts.
var ContentLanguages = []string{
	"en", "fr", "de", "es", "it", "nl", "pt", "pl",
	"cs", "sk", "hu", "ro", "bg", "hr", "sl",
	"sv", "da", "fi", "el", "et", "lv", "lt", "mt", "ga",
	"ja", // CJK plug-in slot (Japanese)
}

// contentLanguageLabels are English display names for AI prompt injection.
// Keep in sync with apps/web/src/lib/content-languages.ts labels.
var contentLanguageLabels = map[string]string{
	"en": "English",
	"fr": "French",
	"de": "German",
	"es": "Spanish",
	"it": "Italian",
	"nl": "Dutch",
	"pt": "Portuguese",
	"pl": "Polish",
	"cs": "Czech",
	"sk": "Slovak",
	"hu": "Hungarian",
	"ro": "Romanian",
	"bg": "Bulgarian",
	"hr": "Croatian",
	"sl": "Slovenian",
	"sv": "Swedish",
	"da": "Danish",
	"fi": "Finnish",
	"el": "Greek",
	"et": "Estonian",
	"lv": "Latvian",
	"lt": "Lithuanian",
	"mt": "Maltese",
	"ga": "Irish",
	"ja": "Japanese",
}

var contentLanguageSet map[string]struct{}

func init() {
	contentLanguageSet = make(map[string]struct{}, len(ContentLanguages))
	for _, code := range ContentLanguages {
		contentLanguageSet[code] = struct{}{}
	}
}

// NormalizeLanguage trims and lowercases a content-language code.
func NormalizeLanguage(raw string) string {
	return strings.ToLower(strings.TrimSpace(raw))
}

// IsAllowedLanguage reports whether code is in ContentLanguages (after normalize).
func IsAllowedLanguage(raw string) bool {
	_, ok := contentLanguageSet[NormalizeLanguage(raw)]
	return ok
}

// ParseLanguage validates and normalizes a content-language code.
// Empty input returns DefaultLanguage when allowEmptyAsDefault is true;
// otherwise empty is an error (use for explicit PATCH language fields).
func ParseLanguage(raw string, allowEmptyAsDefault bool) (string, error) {
	code := NormalizeLanguage(raw)
	if code == "" {
		if allowEmptyAsDefault {
			return DefaultLanguage, nil
		}
		return "", fmt.Errorf("language is required")
	}
	if !IsAllowedLanguage(code) {
		return "", fmt.Errorf("unsupported language %q", code)
	}
	return code, nil
}

// LanguageLabel returns the English display name for a content-language code
// (for AI prompt injection). Empty/unknown codes fall back to English.
func LanguageLabel(raw string) string {
	code, err := ParseLanguage(raw, true)
	if err != nil {
		code = DefaultLanguage
	}
	if label, ok := contentLanguageLabels[code]; ok {
		return label
	}
	return contentLanguageLabels[DefaultLanguage]
}

// LoadLanguage returns companies.language for companyID, or DefaultLanguage.
func LoadLanguage(ctx context.Context, pool *pgxpool.Pool, companyID uuid.UUID) string {
	if pool == nil {
		return DefaultLanguage
	}
	var raw string
	err := pool.QueryRow(ctx, `SELECT COALESCE(language, '') FROM companies WHERE id = $1`, companyID).Scan(&raw)
	if err != nil {
		return DefaultLanguage
	}
	code, err := ParseLanguage(raw, true)
	if err != nil {
		return DefaultLanguage
	}
	return code
}