package smartconfig

import (
	"encoding/json"
	"fmt"
	"os"
	"strings"

	"github.com/tidwall/gjson"
	"gopkg.in/yaml.v3"
)

// 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.
// Returns the value as a YAML string that can be parsed back into the config.
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
	if jsonPath == "." {
		// Parse and convert to YAML for consistency
		var jsonData interface{}
		if err := json.Unmarshal(data, &jsonData); err != nil {
			return "", fmt.Errorf("failed to parse JSON: %w", err)
		}
		yamlBytes, err := yaml.Marshal(jsonData)
		if err != nil {
			return "", fmt.Errorf("failed to marshal to YAML: %w", err)
		}
		return strings.TrimSpace(string(yamlBytes)), nil
	}

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

	// For complex types (objects/arrays), we need to parse and convert to YAML
	if result.IsObject() || result.IsArray() {
		// Use result.Value() to get the underlying interface{}
		jsonData := result.Value()

		// Convert to YAML
		yamlBytes, err := yaml.Marshal(jsonData)
		if err != nil {
			return "", fmt.Errorf("failed to marshal to YAML: %w", err)
		}

		return strings.TrimSpace(string(yamlBytes)), nil
	}

	// For simple types, just return the string representation
	return result.String(), nil
}