/*
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 (
	"bytes"
	"context"
	"crypto/tls"
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"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 = `v0.0.16`
)

var (
	// initialized during build, see Makefile:buildlocal
	APIVERSION, GOVERSION, BUILD, COMMIT, BRANCH string
)

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

type Config struct {
	ConfigFile                     string // -c
	CurrentCluster                 string // -C
	Debug                          bool   // -d
	Output                         string // -o <mode>
	Clusters                       map[string]*Cluster
	DefaultCluster                 *Cluster
	Index                          string   // index: -i
	Failed, Partials               bool     // index: flags
	Shards, Replicas               int      // index create+allocation: -s -r
	Wait                           bool     // index create: -w
	Primary                        bool     // index allocation: -p
	From, To, MaxItems             int      // search: flags
	Filter                         []string // search: -F
	Path                           string   // search+doc sh: -p
	Subhelp                        bool     // search+doc sh: -H
	Tail                           bool     // search: -f [tail]
	Or                             bool     // search: -O
	Range                          string   // search: -r
	TimestampFormat                string   // search: --timestamp-format
	Explain                        bool     // search: -e
	SortBy                         string   // sort: -k
	Ascending                      bool     // sort: -a
	Exclude                        string   // cluster compare: -e (regexp)
	All, Verbose                   bool     // cluster status: -a -v
	Persistent, Transient, Default bool     // -p -t -D cluster settings set
	Force                          bool     // ccr follower renew: -f
	HaveJQ                         bool     // determined at runtime by ourselfes
	DebugHTTP                      bool     // root: --debug-http
	Separator                      string   // role diff: -s
	NotDeployed                    bool     // role diff: -n
	Undefined                      bool     // role diff: -u
	Diff                           bool     // role diff: -D
}

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 err := conf.SetupES(); 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
		}
	} else {
		if len(conf.Clusters) == 1 {
			for name, cluster := range conf.Clusters {
				conf.DefaultCluster = cluster
				conf.CurrentCluster = name
			}
		} else {
			for name, cluster := range conf.Clusters {
				_, err := cluster.ES.Cluster.Health().
					Header("content-type", "application/json").
					Header("accept", "application/json").
					Do(context.Background())

				if err == nil {
					conf.DefaultCluster = cluster
					conf.CurrentCluster = name
				}
			}
		}
	}

	conf.HaveJQ = isJQinstalled()

	conf.PrintDebug()

	return nil
}

func (conf *Config) PrintDebug() {
	if !conf.Debug {
		return
	}

	clone := *conf

	for name := range clone.Clusters {
		clone.Clusters[name] = nil
	}
	clone.DefaultCluster = nil

	fmt.Println("config:")
	repr.Println(clone)
}

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) getTransport() elastictransport.Option {
	transport := &http.Transport{
		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
	}

	if conf.DebugHTTP {
		return elastictransport.WithTransport(
			&DebugTransport{Transport: transport},
		)
	}

	return elastictransport.WithTransport(transport)
}

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(conf.getTransport()),
		)

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

		cluster.ES = es
	}

	return nil
}

// used to print uri, path and body of a request made by the go-client
type DebugTransport struct {
	Transport http.RoundTripper
}

func (t *DebugTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	content := ""
	contentline := ""

	if req.ContentLength > 0 {
		buf := new(bytes.Buffer)
		body, _ := req.GetBody()

		_, err := buf.ReadFrom(body)
		if err != nil {
			return nil, err
		}

		var pretty bytes.Buffer
		err = json.Indent(&pretty, buf.Bytes(), "", "\t")
		if err != nil {
			return nil, fmt.Errorf("json parse error: %s", err)
		}

		content = pretty.String()
		contentline = buf.String()
	}

	slog.Info("req", "host", req.URL.Host, "uri", req.URL.Path, "body", content, "bodyline", contentline)

	return t.Transport.RoundTrip(req)
}

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

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

	return !info.IsDir()
}