/*
Copyright © 2026 Thomas von Dein

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU 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 General Public License for more details.

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

import (
	"crypto/tls"
	"errors"
	"fmt"
	"net/http"
	"os"

	"github.com/alecthomas/repr"
	"github.com/elastic/elastic-transport-go/v8/elastictransport"
	"github.com/elastic/go-elasticsearch/v9"
	"gopkg.in/yaml.v3"
)

const (
	Version string = `v0.0.4`
)

type Cluster struct {
	Uri, User, Pass string
	ES              *elasticsearch.TypedClient
}

type Config struct {
	ConfigFile         string // -c
	CurrentCluster     string // -C
	Debug              bool   // -d
	Clusters           map[string]*Cluster
	DefaultCluster     *Cluster
	Index              string   // index: -i
	Failed, Partials   bool     // index: flags
	Shards, Replicas   int      // index create: -s -r
	Wait               bool     // index create: -w
	From, To, MaxItems int      // search: flags
	Filter             []string // search: -F
	Exclude            string   // cluster compare: -e (regexp)
	All                bool     // cluster status: -a
}

func NewConfig() *Config {
	return &Config{Clusters: map[string]*Cluster{}}
}

func (conf *Config) Init() error {
	DefaultConfig := os.Getenv("HOME") + "/.config/esctl/config.yaml"

	switch {
	case fileExists(DefaultConfig):
		conf.ConfigFile = DefaultConfig
		fallthrough
	case conf.ConfigFile != "":
		if err := conf.LoadConfig(); err != nil {
			return err
		}
	default:
		if err := conf.LoadEnv(); err != nil {
			return err
		}
	}

	if conf.CurrentCluster != "" {
		current, exists := conf.Clusters[conf.CurrentCluster]
		if !exists {
			return fmt.Errorf("no cluster with alias %s configured", conf.CurrentCluster)
		} else {
			conf.DefaultCluster = current
		}
	}

	if conf.Debug {
		repr.Println(conf)
	}

	conf.SetupES()

	return nil
}

func (conf *Config) LoadEnv() error {
	cluster := Cluster{
		Uri:  os.Getenv("ES_URI"),
		User: os.Getenv("ES_USER"),
		Pass: os.Getenv("ES_PASS"),
	}

	switch {
	case cluster.Uri == "":
		return errors.New("ES_URI unset")
	case cluster.User == "":
		return errors.New("ES_USER unset")
	case cluster.Pass == "":
		return errors.New("ES_PASS unset")
	}

	conf.Clusters["default"] = &cluster
	conf.DefaultCluster = &cluster

	return nil
}

func (conf *Config) LoadConfig() error {
	if conf.ConfigFile == "" {
		return nil
	}

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

	newconf := &Config{}

	err = yaml.Unmarshal(data, newconf)
	if err != nil {
		return fmt.Errorf("failed to unmarshal config file: %w", err)
	}

	if len(newconf.Clusters) > 0 {
		conf.Clusters = newconf.Clusters

		_, exists := conf.Clusters["default"]
		if !exists {
			// no "default", just use the first we stumble upon
			for _, cluster := range conf.Clusters {
				conf.DefaultCluster = cluster
				break
			}
		} else {
			conf.DefaultCluster = newconf.Clusters["default"]
		}
	}

	return nil
}

func (conf *Config) SetupES() error {
	for _, cluster := range conf.Clusters {
		es, err := elasticsearch.NewTyped(
			elasticsearch.WithAddresses(cluster.Uri),
			elasticsearch.WithBasicAuth(cluster.User, cluster.Pass),
			elasticsearch.WithTransportOptions(
				elastictransport.WithTransport(
					&http.Transport{
						TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
					},
				),
			),
		)

		if err != nil {
			return fmt.Errorf("failed to setup elasticsearch connection: %w", err)
		}

		cluster.ES = es
	}

	return nil
}

func fileExists(filename string) bool {
	info, err := os.Stat(filename)

	if err != nil {
		// return false on any error
		return false
	}

	return !info.IsDir()
}