hostname-service/api/rule_handlers.go

// Copyright 2024 Florian Beisel
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package api

import (
	"errors"
	"net/http"
	"reflect"

	"git.beisel.it/florian/hostname-service/rules"
	"github.com/gin-gonic/gin"
)

// @Summary		Returns a list of available rules
// @Description	Return a list of names of Rules which are known in the RulesRegistry
// @ID				get-rules
// @Produce		json
// @Security		Bearer
// @Tags			Querying Rules
// @Router			/rules [get]
func ListAvailableRules(c *gin.Context) {
	descriptions := make(map[string]string)
	for category, descriptor := range rules.RulesRegistry {
		descriptions[category] = descriptor.Description
	}
	c.JSON(http.StatusOK, descriptions)
}

func getHostnameRuleByCategory(category string) (rules.HostnameRule, error) {
	if descriptor, exists := rules.RulesRegistry[category]; exists {
		return descriptor.Factory(), nil
	}
	return nil, errors.New("unknown category")
}

// @Summary		Returns details about a rule
// @Description	Returns two obea an Input Object and an Output Object
// @Description	describing the Rules stored values and required parameters
// @ID				get-rule-details
// @Produce		json
// @Success		200	{object}	models.SimpleHostnameResponse	"Hostname"
// @Security		Bearer
// @Tags			Querying Rules
// @Router			/rules/:rule [get]
func GetRuleStruct(c *gin.Context) {
	ruleName := c.Param("rule")
	descriptor, exists := rules.RulesRegistry[ruleName]
	if !exists {
		c.JSON(http.StatusNotFound, gin.H{"error": "Rule not found"})
		return
	}

	// Create an instance of the rule struct for output
	ruleInstance := descriptor.Factory()

	// Check if the rule instance implements EnumProvider for ENUM metadata
	enumProvider, implements := ruleInstance.(rules.EnumProvider)
	var enumInfo map[string][]string
	if implements {
		// Retrieve ENUM metadata from the rule instance
		enumMetadata := enumProvider.EnumOptions()
		enumInfo = make(map[string][]string)
		for _, meta := range enumMetadata {
			enumInfo[meta.FieldName] = meta.Values
		}
	}

	// Serialize the rule instance to JSON for output
	ruleJSON, err := rules.StructToJSON(ruleInstance)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Error serializing rule struct"})
		return
	}

	// Create an instance of the input struct for serialization
	inputInstance := reflect.New(descriptor.InputStruct).Elem().Interface()

	// Serialize the input struct instance to JSON
	inputJSON, err := rules.StructToJSON(inputInstance)
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": "Error serializing input struct"})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"input":  inputJSON, // Input struct with possible ENUM values
		"enums":  enumInfo,  // ENUM metadata if available
		"output": ruleJSON,  // Serialized rule instance
	})
}