3 files changed, 245 insertions, 0 deletions
diff --git a/modules/indexer/internal/meilisearch/filter.go b/modules/indexer/internal/meilisearch/filter.go
new file mode 100644
index 0000000..593177f
--- /dev/null
+++ b/modules/indexer/internal/meilisearch/filter.go
@@ -0,0 +1,119 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package meilisearch
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Filter represents a filter for meilisearch queries.
+// It's just a simple wrapper around a string.
+// DO NOT assume that it is a complete implementation.
+type Filter interface {
+	Statement() string
+}
+
+type FilterAnd struct {
+	filters []Filter
+}
+
+func (f *FilterAnd) Statement() string {
+	var statements []string
+	for _, filter := range f.filters {
+		if s := filter.Statement(); s != "" {
+			statements = append(statements, fmt.Sprintf("(%s)", s))
+		}
+	}
+	return strings.Join(statements, " AND ")
+}
+
+func (f *FilterAnd) And(filter Filter) *FilterAnd {
+	f.filters = append(f.filters, filter)
+	return f
+}
+
+type FilterOr struct {
+	filters []Filter
+}
+
+func (f *FilterOr) Statement() string {
+	var statements []string
+	for _, filter := range f.filters {
+		if s := filter.Statement(); s != "" {
+			statements = append(statements, fmt.Sprintf("(%s)", s))
+		}
+	}
+	return strings.Join(statements, " OR ")
+}
+
+func (f *FilterOr) Or(filter Filter) *FilterOr {
+	f.filters = append(f.filters, filter)
+	return f
+}
+
+type FilterIn string
+
+// NewFilterIn creates a new FilterIn.
+// It supports int64 only, to avoid extra works to handle strings with special characters.
+func NewFilterIn[T int64](field string, values ...T) FilterIn {
+	if len(values) == 0 {
+		return ""
+	}
+	vs := make([]string, len(values))
+	for i, v := range values {
+		vs[i] = fmt.Sprintf("%v", v)
+	}
+	return FilterIn(fmt.Sprintf("%s IN [%v]", field, strings.Join(vs, ", ")))
+}
+
+func (f FilterIn) Statement() string {
+	return string(f)
+}
+
+type FilterEq string
+
+// NewFilterEq creates a new FilterEq.
+// It supports int64 and bool only, to avoid extra works to handle strings with special characters.
+func NewFilterEq[T bool | int64](field string, value T) FilterEq {
+	return FilterEq(fmt.Sprintf("%s = %v", field, value))
+}
+
+func (f FilterEq) Statement() string {
+	return string(f)
+}
+
+type FilterNot string
+
+func NewFilterNot(filter Filter) FilterNot {
+	return FilterNot(fmt.Sprintf("NOT (%s)", filter.Statement()))
+}
+
+func (f FilterNot) Statement() string {
+	return string(f)
+}
+
+type FilterGte string
+
+// NewFilterGte creates a new FilterGte.
+// It supports int64 only, to avoid extra works to handle strings with special characters.
+func NewFilterGte[T int64](field string, value T) FilterGte {
+	return FilterGte(fmt.Sprintf("%s >= %v", field, value))
+}
+
+func (f FilterGte) Statement() string {
+	return string(f)
+}
+
+type FilterLte string
+
+// NewFilterLte creates a new FilterLte.
+// It supports int64 only, to avoid extra works to handle strings with special characters.
+func NewFilterLte[T int64](field string, value T) FilterLte {
+	return FilterLte(fmt.Sprintf("%s <= %v", field, value))
+}
+
+func (f FilterLte) Statement() string {
+	return string(f)
+}
diff --git a/modules/indexer/internal/meilisearch/indexer.go b/modules/indexer/internal/meilisearch/indexer.go
new file mode 100644
index 0000000..feac1d0
--- /dev/null
+++ b/modules/indexer/internal/meilisearch/indexer.go
@@ -0,0 +1,88 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package meilisearch
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/meilisearch/meilisearch-go"
+)
+
+// Indexer represents a basic meilisearch indexer implementation
+type Indexer struct {
+	Client meilisearch.ServiceManager
+
+	url, apiKey string
+	indexName   string
+	version     int
+	settings    *meilisearch.Settings
+}
+
+func NewIndexer(url, apiKey, indexName string, version int, settings *meilisearch.Settings) *Indexer {
+	return &Indexer{
+		url:       url,
+		apiKey:    apiKey,
+		indexName: indexName,
+		version:   version,
+		settings:  settings,
+	}
+}
+
+// Init initializes the indexer
+func (i *Indexer) Init(_ context.Context) (bool, error) {
+	if i == nil {
+		return false, fmt.Errorf("cannot init nil indexer")
+	}
+
+	if i.Client != nil {
+		return false, fmt.Errorf("indexer is already initialized")
+	}
+
+	i.Client = meilisearch.New(i.url, meilisearch.WithAPIKey(i.apiKey))
+
+	_, err := i.Client.GetIndex(i.VersionedIndexName())
+	if err == nil {
+		return true, nil
+	}
+	_, err = i.Client.CreateIndex(&meilisearch.IndexConfig{
+		Uid:        i.VersionedIndexName(),
+		PrimaryKey: "id",
+	})
+	if err != nil {
+		return false, err
+	}
+
+	i.checkOldIndexes()
+
+	_, err = i.Client.Index(i.VersionedIndexName()).UpdateSettings(i.settings)
+	return false, err
+}
+
+// Ping checks if the indexer is available
+func (i *Indexer) Ping(ctx context.Context) error {
+	if i == nil {
+		return fmt.Errorf("cannot ping nil indexer")
+	}
+	if i.Client == nil {
+		return fmt.Errorf("indexer is not initialized")
+	}
+	resp, err := i.Client.Health()
+	if err != nil {
+		return err
+	}
+	if resp.Status != "available" {
+		// See https://docs.meilisearch.com/reference/api/health.html#status
+		return fmt.Errorf("status of meilisearch is not available: %s", resp.Status)
+	}
+	return nil
+}
+
+// Close closes the indexer
+func (i *Indexer) Close() {
+	if i == nil {
+		return
+	}
+	i.Client = nil
+}
diff --git a/modules/indexer/internal/meilisearch/util.go b/modules/indexer/internal/meilisearch/util.go
new file mode 100644
index 0000000..845bdb6
--- /dev/null
+++ b/modules/indexer/internal/meilisearch/util.go
@@ -0,0 +1,38 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package meilisearch
+
+import (
+	"fmt"
+
+	"code.gitea.io/gitea/modules/log"
+)
+
+// VersionedIndexName returns the full index name with version
+func (i *Indexer) VersionedIndexName() string {
+	return versionedIndexName(i.indexName, i.version)
+}
+
+func versionedIndexName(indexName string, version int) string {
+	if version == 0 {
+		// Old index name without version
+		return indexName
+	}
+
+	// The format of the index name is <index_name>_v<version>, not <index_name>.v<version> like elasticsearch.
+	// Because meilisearch does not support "." in index name, it should contain only alphanumeric characters, hyphens (-) and underscores (_).
+	// See https://www.meilisearch.com/docs/learn/core_concepts/indexes#index-uid
+
+	return fmt.Sprintf("%s_v%d", indexName, version)
+}
+
+func (i *Indexer) checkOldIndexes() {
+	for v := 0; v < i.version; v++ {
+		indexName := versionedIndexName(i.indexName, v)
+		_, err := i.Client.GetIndex(indexName)
+		if err == nil {
+			log.Warn("Found older meilisearch index named %q, Forgejo will keep the old NOT DELETED. You can delete the old version after the upgrade succeed.", indexName)
+		}
+	}
+}