/*
|--------------------------------------------------------------------------
| Manifest
|--------------------------------------------------------------------------
|
| Name:
|   - Retriever
|
| Purpose:
|   - Retrieve data from supported resource providers through a unified
|     retrieval interface.
|
| Guideline:
|   - Use registered providers to retrieve resources.
|   - Use resource identifiers to resolve providers.
|   - Use path or fields selection for partial retrieval.
|   - Path and fields are mutually exclusive.
|
| Example:
|   - ObrimRetriever("json", map[string]any{"resource": "metadata"})
|   - ObrimRetriever("json", map[string]any{
|       "resource": "metadata",
|       "path": "application.name",
|     })
|
|--------------------------------------------------------------------------
*/

/*
|--------------------------------------------------------------------------
| Credit
|--------------------------------------------------------------------------
|
| Contributor:
|   - Rajon Ahmed
|   - Scionite
|
|--------------------------------------------------------------------------
*/

package retriever

import (
	"fmt"
	"strings"

	"go/module/essential/visible/service/helper/log"
	"go/module/essential/visible/service/helper/status"
)

// ObrimRetrieverResponse represents the standardized utility response.
type ObrimRetrieverResponse struct {
	Status  bool   `json:"status"`
	Code    string `json:"code"`
	Payload any    `json:"payload"`
}

// ObrimRetrieverJsonProviderRegistry stores registered JSON providers.
var ObrimRetrieverJsonProviderRegistry = map[string]any{}

// ObrimRetrieverDbProviderRegistry stores registered database providers.
var ObrimRetrieverDbProviderRegistry = map[string]any{}

// ObrimRetriever retrieves data using a unified retrieval interface.
func ObrimRetriever(retrievalType string, config map[string]any) map[string]any {
	status.ObrimStatus("INFO", "Retriever started.")
	log.ObrimLog("INIT", "Retriever execution started.")

	if !obrimRetrieverValidateType(retrievalType) {
		return obrimRetrieverBuildResponse(false, "FAILED_UNSUPPORTED_TYPE", nil)
	}

	if !obrimRetrieverValidateConfig(retrievalType, config) {
		return obrimRetrieverBuildResponse(false, "FAILED_INVALID_CONFIGURATION", nil)
	}

	switch retrievalType {
	case "json":
		return obrimRetrieverJson(config)

	case "db":
		return obrimRetrieverDb(config)

	default:
		return obrimRetrieverBuildResponse(false, "FAILED_UNSUPPORTED_TYPE", nil)
	}
}

// ObrimRetrieverJsonRegister registers a JSON provider.
func ObrimRetrieverJsonRegister(resource string, provider any) {
	ObrimRetrieverJsonProviderRegistry[resource] = provider
}

// ObrimRetrieverDbRegister registers a database provider.
func ObrimRetrieverDbRegister(resource string, provider any) {
	ObrimRetrieverDbProviderRegistry[resource] = provider
}

// obrimRetrieverValidateType validates the requested retrieval type.
func obrimRetrieverValidateType(retrievalType string) bool {
	switch retrievalType {
	case "json", "db":
		return true
	default:
		return false
	}
}

// obrimRetrieverValidateConfig validates configuration by retrieval type.
func obrimRetrieverValidateConfig(retrievalType string, config map[string]any) bool {
	switch retrievalType {
	case "json":
		return obrimRetrieverJsonValidate(config)

	case "db":
		return obrimRetrieverDbValidate(config)

	default:
		return false
	}
}

// obrimRetrieverResolveProvider resolves a provider by resource identifier.
func obrimRetrieverResolveProvider(
	retrievalType string,
	resource string,
) (any, bool) {
	switch retrievalType {
	case "json":
		provider, exists := ObrimRetrieverJsonProviderRegistry[resource]
		return provider, exists

	case "db":
		provider, exists := ObrimRetrieverDbProviderRegistry[resource]
		return provider, exists

	default:
		return nil, false
	}
}

// obrimRetrieverBuildResponse builds a standardized response.
func obrimRetrieverBuildResponse(
	success bool,
	code string,
	payload any,
) map[string]any {
	return map[string]any{
		"status":  success,
		"code":    code,
		"payload": payload,
	}
}

// obrimRetrieverJson processes JSON retrieval requests.
func obrimRetrieverJson(config map[string]any) map[string]any {
	resource, _ := config["resource"].(string)

	provider, exists := obrimRetrieverResolveProvider("json", resource)
	if !exists {
		return obrimRetrieverBuildResponse(false, "FAILED_RESOURCE_NOT_FOUND", nil)
	}

	data, err := obrimRetrieverJsonResource(provider)
	if err != nil {
		return obrimRetrieverBuildResponse(false, "FAILED_RESOURCE_NOT_FOUND", nil)
	}

	_, hasPath := config["path"]
	_, hasFields := config["fields"]

	if hasPath {
		return obrimRetrieverJsonPath(data, config)
	}

	if hasFields {
		return obrimRetrieverJsonFields(data, config)
	}

	return obrimRetrieverBuildResponse(
		true,
		"SUCCESS_RESOURCE",
		map[string]any{
			"data": data,
		},
	)
}

// obrimRetrieverJsonResource retrieves a complete resource payload.
func obrimRetrieverJsonResource(provider any) (any, error) {
	switch value := provider.(type) {
	case func() (any, error):
		return value()

	case func() any:
		return value(), nil

	default:
		return nil, fmt.Errorf("invalid provider")
	}
}

// obrimRetrieverJsonPath retrieves a value using dot notation.
func obrimRetrieverJsonPath(
	data any,
	config map[string]any,
) map[string]any {
	path, _ := config["path"].(string)

	value, found := obrimRetrieverResolvePath(data, path)
	if !found {
		return obrimRetrieverBuildResponse(false, "FAILED_PATH_NOT_FOUND", nil)
	}

	return obrimRetrieverBuildResponse(
		true,
		"SUCCESS_PATH",
		map[string]any{
			"data": value,
		},
	)
}

// obrimRetrieverJsonFields retrieves multiple values using field selection.
func obrimRetrieverJsonFields(
	data any,
	config map[string]any,
) map[string]any {
	fields, ok := config["fields"].([]string)
	if !ok {
		rawFields, castOk := config["fields"].([]any)
		if !castOk {
			return obrimRetrieverBuildResponse(false, "FAILED_INVALID_CONFIGURATION", nil)
		}

		fields = make([]string, 0, len(rawFields))

		for _, field := range rawFields {
			fieldString, stringOk := field.(string)
			if !stringOk {
				return obrimRetrieverBuildResponse(false, "FAILED_INVALID_CONFIGURATION", nil)
			}

			fields = append(fields, fieldString)
		}
	}

	result := map[string]any{}

	for _, field := range fields {
		value, found := obrimRetrieverResolvePath(data, field)
		if !found {
			return obrimRetrieverBuildResponse(false, "FAILED_FIELD_NOT_FOUND", nil)
		}

		result[field] = value
	}

	return obrimRetrieverBuildResponse(
		true,
		"SUCCESS_FIELDS",
		map[string]any{
			"data": result,
		},
	)
}

// obrimRetrieverJsonValidate validates JSON configuration.
func obrimRetrieverJsonValidate(config map[string]any) bool {
	resource, exists := config["resource"]
	if !exists {
		return false
	}

	resourceString, ok := resource.(string)
	if !ok || strings.TrimSpace(resourceString) == "" {
		return false
	}

	_, hasPath := config["path"]
	_, hasFields := config["fields"]

	if hasPath && hasFields {
		return false
	}

	return true
}

// obrimRetrieverDb processes database retrieval requests.
func obrimRetrieverDb(config map[string]any) map[string]any {
	return obrimRetrieverBuildResponse(false, "FAILED_NOT_IMPLEMENTED", nil)
}

// obrimRetrieverDbValidate validates database configuration.
func obrimRetrieverDbValidate(config map[string]any) bool {
	return true
}

// obrimRetrieverResolvePath resolves a dot-notation path.
func obrimRetrieverResolvePath(data any, path string) (any, bool) {
	if strings.TrimSpace(path) == "" {
		return nil, false
	}

	current := data

	for _, segment := range strings.Split(path, ".") {
		object, ok := current.(map[string]any)
		if !ok {
			return nil, false
		}

		value, exists := object[segment]
		if !exists {
			return nil, false
		}

		current = value
	}

	return current, true
}