// Copyright 2020 The Chromium OS 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 cmd

import (
	"fmt"
	"os"
	"path/filepath"
	"tnull/driver"

	"github.com/golang/protobuf/jsonpb"
	"github.com/golang/protobuf/proto"
	"github.com/maruel/subcommands"
	tnProto "go.chromium.org/chromiumos/config/go/api/test/harness/tnull/v1"
	metadata "go.chromium.org/chromiumos/config/go/api/test/metadata/v1"
	rtd "go.chromium.org/chromiumos/config/go/api/test/rtd/v1"
	"go.chromium.org/luci/common/errors"
)

const specRelPath = "trunk/infra/tnull/metadata/generated/config.cfg"
const tnullName = "remoteTestDrivers/tnull"

type run struct {
	subcommands.CommandRunBase
	invocationPath string
}

func RunSteps() *subcommands.Command {
	return &subcommands.Command{
		UsageLine: "run-steps -input_json /path/to/input.json",
		ShortDesc: "run an Invocation object.",
		CommandRun: func() subcommands.CommandRun {
			r := &run{}
			r.Flags.StringVar(&r.invocationPath, "input_json", "", "Path that contains a JSON-encoded rtd.Invocation object")
			return r
		},
	}
}

func (r *run) Run(a subcommands.Application, args []string, env subcommands.Env) int {
	if err := r.innerRun(a, args, env); err != nil {
		fmt.Fprintf(a.GetErr(), "%s\n", err)
		return 1
	}
	return 0
}

func (r *run) innerRun(a subcommands.Application, args []string, env subcommands.Env) error {
	if err := r.validateArgs(); err != nil {
		return errors.Annotate(err, "validation").Err()
	}

	var inv rtd.Invocation
	if err := readJSONPb(r.invocationPath, &inv); err != nil {
		return errors.Annotate(err, "reading in the Invocation").Err()
	}
	if inv.GetRequests() == nil || len(inv.GetRequests()) == 0 {
		return errors.Reason("no requests in invocation").Err()
	}

	lookup, err := extractTestsFromSpecification()
	if err != nil {
		return err
	}

	conf := inv.ProgressSinkClientConfig
	reqs := inv.Requests
	errs := errors.MultiError{}

	for _, req := range reqs {
		fmt.Fprintf(a.GetOut(), "req %s: 'executing' test %s\n", req.Name, req.Test)
		if steps, present := lookup.Lookup[req.Test]; !present {
			errs = append(errs, errors.Reason("no test with the name %s", req.Test).Err())
		} else {
			steps.Setup.Config = conf
			r.Execute(req.Test, steps)
		}
	}
	if len(errs) == 0 {
		return nil
	}
	return errs
}

func extractTestsFromSpecification() (*tnProto.TestMap, error) {
	p, err := specPath()
	if err != nil {
		return nil, errors.Annotate(err, "extracting tests from spec").Err()
	}
	var s metadata.Specification
	if err := readJSONPb(p, &s); err != nil {
		return nil, errors.Annotate(err, "extracting tests from spec").Err()
	}
	testMap := &tnProto.TestMap{Lookup: map[string]*tnProto.Steps{}}
	for _, rtd := range s.RemoteTestDrivers {
		if rtd.Name != tnullName {
			return nil, errors.Reason(
				"bad specification, RTD was %s, should be %s",
				rtd.Name, tnullName).Err()
		}
		marshaler := jsonpb.Marshaler{}
		for _, test := range rtd.Tests {
			steps, err := detailsToSteps(marshaler, test.Informational)
			if err != nil {
				return nil, errors.Annotate(
					err, "extracting tests from spec").Err()
			}
			testMap.Lookup[test.Name] = steps
		}
	}
	return testMap, nil
}

func detailsToSteps(m jsonpb.Marshaler, info *metadata.Informational) (*tnProto.Steps, error) {
	jsonSteps, err := m.MarshalToString(info.Details.GetFields()["steps"])
	if err != nil {
		return nil, errors.Annotate(err, "Details>json").Err()
	}
	var steps tnProto.Steps
	if err := jsonpb.UnmarshalString(jsonSteps, &steps); err != nil {
		return nil, errors.Annotate(err, "json>Steps").Err()
	}
	return &steps, nil
}

func (r *run) Execute(name string, s *tnProto.Steps) error {
	var d driver.Driver
	if err := d.Setup(name, *s.Setup); err != nil {
		return err
	}
	for _, st := range s.Steps {
		ste := st.GetStep()
		switch t := ste.(type) {
		case *tnProto.Step_Archive:
			req := st.GetArchive().GetCommonArgs().GetRequestName()
			return d.Archive(req)
		case *tnProto.Step_Log:
			req := st.GetLog().GetCommonArgs().GetRequestName()
			return d.Log(req)
		case *tnProto.Step_Result:
			req := st.GetResult().GetCommonArgs().GetRequestName()
			return d.Result(req)
		case *tnProto.Step_Other:
			step := st.GetOther()
			return errors.Reason(
				"driver has no method %s or support for args %v",
				step.GetMethodName(), step.GetArgs(),
			).Err()
		default:
			_ = t
			return errors.Reason("no step specified").Err()
		}
	}
	return nil
}

func (r *run) validateArgs() error {
	if r.invocationPath == "" {
		return fmt.Errorf("input_json must specify an rtd.Invocation")
	}
	return nil
}

// readJSONPb reads a JSON string from inFile and unpacks it as a proto.
// Unexpected fields are ignored.
func readJSONPb(inFile string, payload proto.Message) error {
	r, err := os.Open(inFile)
	if err != nil {
		return errors.Annotate(err, "read JSON pb").Err()
	}
	defer r.Close()

	unmarshaler := jsonpb.Unmarshaler{AllowUnknownFields: true}
	if err := unmarshaler.Unmarshal(r, payload); err != nil {
		return errors.Annotate(err, "read JSON pb").Err()
	}
	return nil
}

func specPath() (string, error) {
	if home, err := os.UserHomeDir(); err != nil {
		return "", err
	} else {
		return filepath.Join(home, specRelPath), nil
	}
}