/*
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 es

import (
	"context"
	"errors"
	"fmt"
	"log/slog"
	"slices"
	"sync"

	"codeberg.org/scip/esctl/pkg/cfg"
	"github.com/elastic/go-elasticsearch/v9/typedapi/ccr/stats"
	"github.com/elastic/go-elasticsearch/v9/typedapi/cluster/health"
	"github.com/elastic/go-elasticsearch/v9/typedapi/core/info"
	"github.com/elastic/go-elasticsearch/v9/typedapi/types"
)

const (
	ResponseHealth = iota
	ResponseInfo
	ResponseCcr
)

type ClusterIndices map[string]map[string]*types.IndicesRecord

type apiResponse struct {
	error  error
	info   *info.Response
	health *health.Response
	ccr    *stats.Response
	which  int
}

func ClusterCompare(conf *cfg.Config, leader, follower string) error {
	if !checkClusterFollower(conf, leader) {
		return errors.New("leader/follower attribution is invalid, reverse cluster attribution and retry")
	}

	indices := ClusterIndices{}

	for _, alias := range []string{leader, follower} {
		cat := conf.Clusters[alias].ES.Cat.Indices().
			// we need to add custom request headers, required for older ES instances
			Header("content-type", "application/json").
			Header("accept", "application/json")

		res, err := cat.Do(context.Background())
		if err != nil {
			return fmt.Errorf("failed to get indicies on %s: %s", alias, err)
		}

		indices[alias] = make(map[string]*types.IndicesRecord, len(res))

		for _, index := range res {
			indices[alias][*index.Index] = &index
		}
	}

	if !checkClusterStatus(conf, leader, follower) {
		return errors.New("one of the two clusters is in a failed state")
	}

	findIlmErrors(conf, leader, follower)

	if findIndicesOnlyOnLeader(conf, indices, leader, follower) &&
		findOrphanedIndices(conf, indices, leader, follower) &&
		findFailedFollowerIndices(conf, indices, follower) {
		fmt.Println("everything's hunky-dory.")
	}

	return nil
}

func ClusterList(conf *cfg.Config) error {
	table := NewTable(3, len(conf.Clusters))

	table.Addheaders("cluster", "uri", "default")

	idx := 0

	names := make([]string, len(conf.Clusters))
	for name := range conf.Clusters {
		names[idx] = name
		idx++
	}

	slices.Sort(names)

	idx = 0

	for idx, name := range names {
		current := name == "default" || name == conf.CurrentCluster
		cluster := conf.Clusters[name]

		_, err := cluster.ES.Cluster.Health().
			Header("content-type", "application/json").
			Header("accept", "application/json").
			Do(context.Background())

		if err == nil {
			name = Colorize("green", name)
		}

		table.entries[idx] = []string{name, cluster.Uri, fmt.Sprintf("%t", current)}
		idx++
	}

	if err := table.PrintMarkdown(); err != nil {
		return err
	}

	return nil
}

// We're using goroutines  here to parallelize API  requests, since we
// have to do 3 of'em for each cluster. This speeds things up.
func ClusterStatus(conf *cfg.Config) error {
	clusters := []string{}

	if conf.All {
		for key := range conf.Clusters {
			clusters = append(clusters, key)
		}
	} else {
		clusters = []string{"default"}
	}

	for _, cluster := range clusters {
		es := conf.DefaultCluster.ES
		if cluster != "default" {
			es = conf.Clusters[cluster].ES
		}

		responses := make(chan apiResponse, 3)
		wg := &sync.WaitGroup{}

		wg.Add(3)
		go getClusterData(es, wg, responses, "health")
		go getClusterData(es, wg, responses, "info")
		go getClusterData(es, wg, responses, "ccrstats")

		wg.Wait()

		var clusterhealth *health.Response
		var info *info.Response
		var ccrstats *stats.Response

		for i := 0; i < 3; i++ {
			r := <-responses

			if r.error != nil {
				return r.error
			}

			switch r.which {
			case ResponseHealth:
				clusterhealth = r.health
			case ResponseCcr:
				ccrstats = r.ccr
			case ResponseInfo:
				info = r.info
			}
		}

		slog.Debug("ES result", "cluster health", clusterhealth)

		ccrfollowing := ""
		if len(ccrstats.AutoFollowStats.AutoFollowedClusters) > 0 {
			// is following another cluster
			ccrfollowing = fmt.Sprintf("%s (%d/%d)",
				ccrstats.AutoFollowStats.AutoFollowedClusters[0].ClusterName,
				ccrstats.AutoFollowStats.NumberOfSuccessfulFollowIndices,
				ccrstats.AutoFollowStats.NumberOfFailedFollowIndices,
			)
		}

		table := NewTable(2, 5)
		table.Addheaders(cluster, "status")

		table.entries = [][]string{
			{"Cluster Name", Colorize(clusterhealth.Status.Name, clusterhealth.ClusterName)},
			{"ES Version", info.Version.Int},
			{"Active Shards", fmt.Sprintf("%d", clusterhealth.ActiveShards)},
			{"Active Primary Shards", fmt.Sprintf("%d", clusterhealth.ActivePrimaryShards)},
			{"Indicies", fmt.Sprintf("%d", len(clusterhealth.Indices))},
			{"Nodes", fmt.Sprintf("%d", clusterhealth.NumberOfNodes)},
			{"AutoFollow (success/failed indices)", ccrfollowing},
		}

		if err := table.PrintMarkdown(); err != nil {
			return err
		}
	}

	return nil
}