/*
Copyright © 2026 Craig Williams <craig@avsdev.uk>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package config

import (
	"encoding/json"
	"fmt"
	"log/slog"
	"reflect"
	"strings"

	"github.com/spf13/viper"
	"go.yaml.in/yaml/v3"
)

const EnvPrefix string = "JOBSEARCH"
const EtcConfigPath string = "/etc/job-search"

// Each field's cfg tag must match the section's JSCK* constant.
type JobSearchConfig struct {
	Logging JobSearchConfigLogging `cfg:"logging"`
	Sources JobSearchConfigSources `cfg:"sources"`
}

// Default configuration, taken from the default struct tags
func LoadDefaultConfig() {
	var conf JobSearchConfig
	if err := applyDefaults(&conf); err != nil {
		panic(fmt.Sprintf("config: %v", err))
	}
	LoadToViper(conf)
}

func (c JobSearchConfig) Map() map[string]any { return mapOf(c) }

func (c JobSearchConfig) Flatten() map[string]any { return flattenOf("", c) }

func (c JobSearchConfig) TypeOf(key string) (reflect.Kind, error) {
	return typeOf(c, key)
}

func (c JobSearchConfig) ValueOf(key string) (any, error) {
	return valueOf(c, key)
}

func (c *JobSearchConfig) SetValue(key string, value any) error {
	return setValue(c, key, value)
}

// Utility method for loading a configuration from Viper
func LoadFromViper(conf *JobSearchConfig) {
	keys := viper.AllKeys()
	for idx := range keys {
		key := keys[idx]
		keyType, _ := conf.TypeOf(key)
		if keyType == reflect.Invalid {
			continue
		}
		switch keyType {
		case reflect.String:
			conf.SetValue(key, viper.GetString(key))
		case reflect.Int:
			conf.SetValue(key, viper.GetInt(key))
		case reflect.Bool:
			conf.SetValue(key, viper.GetBool(key))
		default:
			slog.Error(fmt.Sprintf("unknown key type: %s", keyType))
		}
	}
}

// Utility method for loading a configuration into Viper as defaults
func LoadToViper(conf JobSearchConfig) {
	flatMap := conf.Flatten()
	for key := range flatMap {
		viper.SetDefault(key, flatMap[key])
	}
}

// Converts configuration to a string in flat dotted format
func (conf JobSearchConfig) String() string {
	var sb strings.Builder
	for k, v := range conf.Flatten() {
		typ, _ := conf.TypeOf(k)
		sb.WriteString(fmt.Sprint(k, " = ", v, " <", typ, ">\n"))
	}
	return sb.String()
}

// Converts configuration to JSON
func (conf JobSearchConfig) JSON() string {
	confMap := conf.Map()
	jbytes, _ := json.MarshalIndent(confMap, "", "  ")
	return string(jbytes)
}

// Converts configuration to YAML
func (conf JobSearchConfig) YAML() string {
	confMap := conf.Map()
	ybytes, _ := yaml.Marshal(confMap)
	return string(ybytes)
}