// Copyright 2015 The Go 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 buildlet

import (
	"context"
	"errors"
	"fmt"
	"io"
	"net"
	"net/http"
	"os"
	"strings"
)

// RemoteClient is a subset of methods that can be used by a gomote client.
type RemoteClient interface {
	Close() error
	Exec(ctx context.Context, cmd string, opts ExecOpts) (remoteErr, execErr error)
	GetTar(ctx context.Context, dir string) (io.ReadCloser, error)
	ListDir(ctx context.Context, dir string, opts ListDirOpts, fn func(DirEntry)) error
	Put(ctx context.Context, r io.Reader, path string, mode os.FileMode) error
	PutTar(ctx context.Context, r io.Reader, dir string) error
	PutTarFromURL(ctx context.Context, tarURL, dir string) error
	ProxyTCP(port int) (io.ReadWriteCloser, error)
	RemoteName() string
	RemoveAll(ctx context.Context, paths ...string) error
	WorkDir(ctx context.Context) (string, error)
}

// Client is an interface that represent the methods exposed by client. The
// fake buildlet client should be used instead of client when testing things that
// use the client interface.
// This includes a number of coordinator-internal details; users outside the
// coordinator should use RemoteClient.
type Client interface {
	RemoteClient
	ConnectSSH(user, authorizedPubKey string) (net.Conn, error)
	IPPort() string
	InstanceName() string
	IsBroken() bool
	MarkBroken()
	Name() string
	ProxyRoundTripper() http.RoundTripper
	SetDescription(v string)
	SetDialer(dialer func(context.Context) (net.Conn, error))
	SetHTTPClient(httpClient *http.Client)
	SetInstanceName(v string)
	SetName(name string)
	SetOnHeartbeatFailure(fn func())
	Status(ctx context.Context) (Status, error)
	String() string
	URL() string
}

var errUnimplemented = errors.New("unimplemented function")

var _ Client = (*FakeClient)(nil)

// FakeClient is a fake buildlet client used for testing. Not all functions are implemented.
type FakeClient struct {
	closeFuncs   []func()
	instanceName string
	name         string
}

// Close is a fake client closer.
func (fc *FakeClient) Close() error {
	for _, f := range fc.closeFuncs {
		f()
	}
	return nil
}

// ConnectSSH connects to a fake SSH server.
func (fc *FakeClient) ConnectSSH(user, authorizedPubKey string) (net.Conn, error) {
	return nil, errUnimplemented
}

// Exec fakes the execution.
func (fc *FakeClient) Exec(ctx context.Context, cmd string, opts ExecOpts) (remoteErr, execErr error) {
	if cmd == "" {
		return nil, errors.New("invalid command")
	}
	if opts.Output == nil {
		return nil, nil
	}
	out := []byte("<this is a song that never ends>")
	for it := 0; it < 3; it++ {
		if n, err := opts.Output.Write(out); n != len(out) || err != nil {
			return nil, fmt.Errorf("Output.Write(...) = %d, %q; want %d, no error", n, err, len(out))
		}
	}
	return nil, nil
}

// InstanceName gives the fake instance name.
func (fc *FakeClient) InstanceName() string { return fc.instanceName }

// GetTar gives a vake tar zipped directory.
func (fc *FakeClient) GetTar(ctx context.Context, dir string) (io.ReadCloser, error) {
	r := strings.NewReader("the gopher goes to the sea and fights the kraken")
	return io.NopCloser(r), nil
}

// IPPort provides a fake ip and port pair.
func (fc *FakeClient) IPPort() string { return "" }

// IsBroken returns a fake broken response.
func (fc *FakeClient) IsBroken() bool { return false }

// ListDir lists a directory on a fake buildlet.
func (fc *FakeClient) ListDir(ctx context.Context, dir string, opts ListDirOpts, fn func(DirEntry)) error {
	if dir == "" || fn == nil {
		return errors.New("invalid arguments")
	}
	var lsOutput = `drwxr-xr-x      gocache/
drwxr-xr-x      tmp/`
	lines := strings.Split(lsOutput, "\n")
	for _, line := range lines {
		fn(DirEntry{Line: line})
	}
	return nil
}

// MarkBroken marks the fake client as broken.
func (fc *FakeClient) MarkBroken() {}

// Name is the name of the fake client.
func (fc *FakeClient) Name() string { return fc.name }

// ProxyRoundTripper provides a fake proxy.
func (fc *FakeClient) ProxyRoundTripper() http.RoundTripper { return nil }

// ProxyTCP provides a fake proxy.
func (fc *FakeClient) ProxyTCP(port int) (io.ReadWriteCloser, error) { return nil, errUnimplemented }

// Put places a file on a fake buildlet.
func (fc *FakeClient) Put(ctx context.Context, r io.Reader, path string, mode os.FileMode) error {
	// TODO(go.dev/issue/48742) add a file system implementation which would enable proper testing.
	if path == "" {
		return errors.New("invalid argument")
	}
	return nil
}

// PutTar fakes putting  a tar zipped file on a buildldet.
func (fc *FakeClient) PutTar(ctx context.Context, r io.Reader, dir string) error {
	// TODO(go.dev/issue/48742) add a file system implementation which would enable proper testing.
	return errUnimplemented
}

// PutTarFromURL fakes putting a tar zipped file on a builelt.
func (fc *FakeClient) PutTarFromURL(ctx context.Context, tarURL, dir string) error {
	return nil
}

// RemoteName gives the remote name of the fake buildlet.
func (fc *FakeClient) RemoteName() string { return "" }

// SetDescription sets the description on a fake client.
func (fc *FakeClient) SetDescription(v string) {}

// SetDialer sets the function that creates a new connection to the fake buildlet.
func (fc *FakeClient) SetDialer(dialer func(context.Context) (net.Conn, error)) {}

// SetInstanceName sets the GCE or EC2 instance name on a fake client.
func (fc *FakeClient) SetInstanceName(v string) {
	fc.instanceName = v
}

// SetHTTPClient sets the HTTP client on a fake client.
func (fc *FakeClient) SetHTTPClient(httpClient *http.Client) {}

// SetName sets the name on a fake client.
func (fc *FakeClient) SetName(name string) {
	fc.name = name
}

// SetOnHeartbeatFailure sets a function to be called when heartbeats against this fake buildlet fail.
func (fc *FakeClient) SetOnHeartbeatFailure(fn func()) {}

// Status provides a status on the fake client.
func (fc *FakeClient) Status(ctx context.Context) (Status, error) { return Status{}, errUnimplemented }

// String provides a fake string representation of the client.
func (fc *FakeClient) String() string { return "" }

// URL is the URL for a fake buildlet.
func (fc *FakeClient) URL() string { return "" }

// WorkDir is the working directory for the fake buildlet.
func (fc *FakeClient) WorkDir(ctx context.Context) (string, error) {
	return "/work", nil
}

// RemoveAll deletes the provided paths, relative to the work directory for a fake buildlet.
func (fc *FakeClient) RemoveAll(ctx context.Context, paths ...string) error {
	// TODO(go.dev/issue/48742) add a file system implementation which would enable proper testing.
	return nil
}