// Copyright 2022 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package main

import (
	"context"
	"net/http"
	"sync"

	buildbucketpb "go.chromium.org/luci/buildbucket/proto"
	gerritpb "go.chromium.org/luci/common/proto/gerrit"

	"go.fuchsia.dev/infra/gerrit"
)

// gerritClientKey is the key by which gerrit.Client structs are hashed in the
// gerritMultiClient cache.
type gerritClientKey struct {
	hostname string
	project  string
}

// gerritMultiClient implements a wrapper around multiple per-project gerrit
// clients, as the gerrit.Client struct is scoped to a single repository.
type gerritMultiClient struct {
	authClient *http.Client
	clients    map[gerritClientKey]*gerrit.Client
	// Protects access to the `clients` map.
	mu sync.Mutex
}

func (c *gerritMultiClient) getChange(
	ctx context.Context,
	change *buildbucketpb.GerritChange,
	opts ...gerritpb.QueryOption,
) (*gerritpb.ChangeInfo, error) {
	client, err := c.clientForProject(change.Host, change.Project)
	if err != nil {
		return nil, err
	}
	return client.GetChange(ctx, change.Change, opts...)
}

func (c *gerritMultiClient) clientForProject(hostname, project string) (*gerrit.Client, error) {
	key := gerritClientKey{hostname: hostname, project: project}
	c.mu.Lock()
	defer c.mu.Unlock()
	if client, ok := c.clients[key]; ok {
		return client, nil
	}
	client, err := gerrit.NewClient(hostname, project, c.authClient)
	if err != nil {
		return nil, err
	}
	c.clients[key] = client
	return client, nil
}