package asr

import (
	"encoding/json"
	"fmt"
)

// HotwordEntry represents a single hotword for context JSON.
type HotwordEntry struct {
	Word string `json:"word"`
}

// HotwordsContext represents the context JSON structure for hotwords.
type HotwordsContext struct {
	Hotwords []HotwordEntry `json:"hotwords"`
}

// BuildHotwordsContext converts a list of hotword strings to context JSON string.
// Returns empty string if hotwords list is empty.
func BuildHotwordsContext(hotwords []string) (string, error) {
	if len(hotwords) == 0 {
		return "", nil
	}

	entries := make([]HotwordEntry, 0, len(hotwords))
	for _, word := range hotwords {
		if word != "" {
			entries = append(entries, HotwordEntry{Word: word})
		}
	}

	if len(entries) == 0 {
		return "", nil
	}

	ctx := HotwordsContext{Hotwords: entries}
	data, err := json.Marshal(ctx)
	if err != nil {
		return "", fmt.Errorf("marshal hotwords context: %w", err)
	}

	return string(data), nil
}