/*
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"
	"fmt"
	"regexp"
	"strings"

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

const (
	DefaultExclude = `(part|monitoring|.internal|metrics-endpoint)`
)

func checkClusterIsLeader(conf *cfg.Config, leader string) bool {
	stats, err := conf.Clusters[leader].ES().Ccr.Stats().
		Do(context.Background())
	if err != nil {
		fmt.Printf("failed to get ccr stats from %s: %s", leader, esErrorString(err))
		return false
	}

	if len(stats.AutoFollowStats.AutoFollowedClusters) == 0 {
		// is not following anyone
		return true
	}

	if stats.AutoFollowStats.AutoFollowedClusters[0].ClusterName != "" {
		fmt.Println("leader/follower attribution is invalid, reverse cluster attribution and retry")
		return false
	}

	return true
}

// checks if both clusters are green
func checkClusterStatus(conf *cfg.Config, leader, follower string) bool {
	status := map[string]*health.Response{}

	for _, cluster := range []string{leader, follower} {
		st, err := conf.Clusters[leader].ES().Cluster.Health().
			Do(context.Background())
		if err != nil {
			fmt.Printf("failed to get health from %s: %s", cluster, esErrorString(err))
			return false
		}

		status[cluster] = st
	}

	table := printer.NewTable(conf, 3, 6)

	table.Addheaders("setting", "leader:"+leader, "follower:"+follower)

	table.Entries = [][]any{
		{"Cluster Name", status[leader].ClusterName, status[follower].ClusterName},
		{"Cluster Status",
			printer.Colorize(conf, status[leader].Status.Name, status[leader].Status.Name),
			printer.Colorize(conf, status[follower].Status.Name, status[follower].Status.Name),
		},
		{"Active Shards",
			status[leader].ActiveShards,
			status[follower].ActiveShards,
		},
		{"Active Primary Shards",
			status[leader].ActivePrimaryShards,
			status[follower].ActivePrimaryShards,
		},
		{"Indicies",
			len(status[leader].Indices),
			len(status[follower].Indices),
		},
		{"Nodes",
			status[leader].NumberOfNodes,
			status[follower].NumberOfNodes,
		},
	}

	if err := table.Print(); err != nil {
		fmt.Println(err)
		return false
	}

	fmt.Println()

	if status[leader].Status.Name == "green" && status[follower].Status.Name == "green" {
		return true
	}

	return false
}

// finds indices on both clusters which have ilm errors
func findIlmErrors(conf *cfg.Config, leader, follower string) bool {
	failed := map[string]map[string]any{}

	for _, cluster := range []string{leader, follower} {
		ilm, err := conf.Clusters[cluster].ES().Ilm.ExplainLifecycle("_all").
			OnlyManaged(true).
			Do(context.Background())
		if err != nil {
			fmt.Printf("failed to get ilm status from %s: %s", cluster, esErrorString(err))
			return false
		}

		failed[cluster] = map[string]any{}

		for name, ilmstate := range ilm.Indices {
			count := ilmstate.(*types.LifecycleExplainManaged).FailedStepRetryCount

			if count != nil && *count > 0 {
				failed[cluster][name] = *count
			}
		}
	}

	if len(failed[leader]) == 0 && len(failed[follower]) == 0 {
		return true
	}

	for idx, cluster := range []string{leader, follower} {
		which := "leader"
		if idx > 0 {
			which = "follower"
		}

		if len(failed[cluster]) > 0 {
			idx := 0
			table := printer.NewTable(conf, 2, len(failed[cluster]))
			table.Addheaders("ilm errors on "+which, "errors")

			for name, count := range failed[cluster] {
				table.Entries[idx] = []any{name, count}
				idx++
			}

			table.Sort()

			if err := table.Print(); err != nil {
				fmt.Println(err)
				return false
			}
		}
	}

	return false
}

// find unsynchronized indicies only present on leader
func findIndicesOnlyOnLeader(conf *cfg.Config, indices ClusterIndices, leader, follower string) bool {
	exclude := regexp.MustCompile(DefaultExclude)
	if conf.Exclude != "" {
		exclude = regexp.MustCompile(conf.Exclude)
	}

	indexOnlyOnLeader := map[string]*types.IndicesRecord{}
	for name, index := range indices[leader] {
		if exclude.MatchString(name) {
			continue
		}

		_, followerHasIt := indices[follower][name]
		if !followerHasIt {
			// fetch index details
			res, err := conf.Clusters[leader].ES().Indices.Get(name).
				Do(context.Background())
			if err != nil {
				continue // ignore it then
			}

			_, defined := res[name]
			if !defined {
				// json response map didn't contain the index
				continue
			}

			isWritable := false
			for _, alias := range res[name].Aliases {
				if *alias.IsWriteIndex {
					isWritable = true
					break
				}
			}

			if isWritable {
				// ignore index if associated alias index is writing
				continue
			}

			indexOnlyOnLeader[name] = index
		}
	}

	if len(indexOnlyOnLeader) == 0 {
		return true
	}

	idx := 0
	table := printer.NewTable(conf, 3, len(indexOnlyOnLeader))
	table.Addheaders("index only on leader", "size", "docscount")

	for name, index := range indexOnlyOnLeader {
		name := printer.Colorize(conf, "red", name)

		table.Entries[idx] = []any{name, *index.DatasetSize, *index.DocsCount}
		idx++
	}

	table.Sort()
	if err := table.Print(); err != nil {
		fmt.Println(err)
		return false
	}

	return false
}

// find indices only present on follower
func findOrphanedIndices(conf *cfg.Config, indices ClusterIndices, leader, follower string) bool {
	orphaned := map[string]*types.IndicesRecord{}

	for name, index := range indices[follower] {
		_, leaderHasIt := indices[leader][name]
		if !leaderHasIt {
			// fetch index details
			res, err := conf.Clusters[follower].ES().Indices.Get(name).
				Do(context.Background())
			if err != nil {
				continue // ignore it then
			}

			_, defined := res[name]
			if !defined {
				// json response map didn't contain the index
				continue
			}

			orphaned[name] = index
		}
	}

	if len(orphaned) == 0 {
		return true
	}

	idx := 0
	table := printer.NewTable(conf, 3, len(orphaned))
	table.Addheaders("orphaned index on follower", "size", "docscount")

	for name, index := range orphaned {
		name := printer.Colorize(conf, "red", name)

		table.Entries[idx] = []any{name, *index.DatasetSize, *index.DocsCount}
		idx++
	}

	table.Sort()
	if err := table.Print(); err != nil {
		fmt.Println(err)
		return false
	}

	return false
}

// find red indices on follower
func findFailedFollowerIndices(conf *cfg.Config, indices ClusterIndices, follower string) bool {
	red := map[string]*types.IndicesRecord{}

	for name, index := range indices[follower] {
		if *index.Health == "red" {
			red[name] = index
		}
	}

	if len(red) == 0 {
		return true
	}

	idx := 0
	table := printer.NewTable(conf, 3, len(red))
	table.Addheaders("red index on follower", "size", "docscount")

	for name, index := range red {
		name := printer.Colorize(conf, "red", name)

		table.Entries[idx] = []any{name, *index.DatasetSize, *index.DocsCount}
		idx++
	}

	table.Sort()
	if err := table.Print(); err != nil {
		fmt.Println(err)
		return false
	}

	return false
}

func splitArg(arg string) (string, string) {
	parts := strings.Split(arg, ":")

	switch len(parts) {
	case 0:
		fallthrough
	case 1:
		return arg, ""
	default:
		return parts[0], parts[1]
	}
}