/*
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"

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

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

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

func ClusterCompare(conf *cfg.Config, leader, follower string) error {
	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("Error getting indicies on %s: %s", alias, err)
		}

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

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

	findIndicesOnlyOnMaster(conf, indices, leader, follower)

	return nil
}

// look for indicies only on leader
func findIndicesOnlyOnMaster(conf *cfg.Config, indices ClusterIndices, leader, follower string) {
	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).
				Header("content-type", "application/json").
				Header("accept", "application/json").
				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
		}
	}

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

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

		table.entries[idx] = []string{name, *index.DatasetSize, *index.DocsCount}
		idx++
	}

	table.Sort()
	table.PrintMarkdown()
}