package smartconfig

import (
	"fmt"
	"os"
	"strings"

	"github.com/tidwall/gjson"
)

// JSONResolver reads values from JSON files.
// Usage: ${JSON:/path/to/file.json:json.path}
type JSONResolver struct{}

// Resolve reads a JSON file and extracts the value at the specified path.
func (r *JSONResolver) Resolve(value string) (string, error) {
	parts := strings.SplitN(value, ":", 2)
	if len(parts) != 2 {
		return "", fmt.Errorf("invalid JSON resolver format, expected FILE:PATH")
	}

	filePath := parts[0]
	jsonPath := parts[1]

	data, err := os.ReadFile(filePath)
	if err != nil {
		return "", fmt.Errorf("failed to read JSON file %s: %w", filePath, err)
	}

	// gjson supports JSON5 syntax including comments, trailing commas, etc.
	// Special case: if path is ".", return the entire JSON as a string
	if jsonPath == "." {
		return string(data), nil
	}

	result := gjson.GetBytes(data, jsonPath)
	if !result.Exists() {
		return "", fmt.Errorf("path %s not found in JSON file", jsonPath)
	}

	// Return the raw value as a string
	return result.String(), nil
}