/*
Copyright 2021 The Dapr Authors
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
    http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package temporal

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"reflect"
	"time"

	"go.temporal.io/api/enums/v1"
	"go.temporal.io/sdk/client"

	"github.com/dapr/components-contrib/metadata"
	"github.com/dapr/components-contrib/workflows"
	"github.com/dapr/kit/logger"
)

type TemporalWF struct {
	client client.Client
	logger logger.Logger
}

type temporalMetadata struct {
	Identity  string `json:"identity" mapstructure:"identity"`
	HostPort  string `json:"hostport" mapstructure:"hostport"`
	Namespace string `json:"namespace" mapstructure:"namespace"`
}

// NewTemporalWorkflow returns a new workflow.
func NewTemporalWorkflow(logger logger.Logger) workflows.Workflow {
	s := &TemporalWF{
		logger: logger,
	}
	return s
}

func (c *TemporalWF) Init(metadata workflows.Metadata) error {
	c.logger.Debugf("Temporal init start")
	m, err := c.parseMetadata(metadata)
	if err != nil {
		return err
	}
	cOpt := client.Options{}
	if m.HostPort != "" {
		cOpt.HostPort = m.HostPort
	}
	if m.Identity != "" {
		cOpt.Identity = m.Identity
	}
	if m.Namespace != "" {
		cOpt.Namespace = m.Namespace
	}
	// Create the workflow client
	newClient, err := client.Dial(cOpt)
	if err != nil {
		return err
	}
	c.client = newClient

	return nil
}

func (c *TemporalWF) Start(ctx context.Context, req *workflows.StartRequest) (*workflows.StartResponse, error) {
	c.logger.Debugf("starting workflow")

	if len(req.Options) == 0 {
		c.logger.Debugf("no options provided")
		return nil, errors.New("no options provided. At the very least, a task queue is needed")
	}

	if _, ok := req.Options["task_queue"]; !ok {
		c.logger.Debugf("no task queue provided")
		return nil, errors.New("no task queue provided")
	}
	taskQ := req.Options["task_queue"]

	opt := client.StartWorkflowOptions{ID: req.InstanceID, TaskQueue: taskQ}

	var inputArgs interface{}
	if err := decodeInputData(req.WorkflowInput, &inputArgs); err != nil {
		return nil, fmt.Errorf("error decoding workflow input data: %w", err)
	}

	run, err := c.client.ExecuteWorkflow(ctx, opt, req.WorkflowName, inputArgs)
	if err != nil {
		return nil, fmt.Errorf("error executing workflow: %w", err)
	}
	wfStruct := workflows.StartResponse{InstanceID: run.GetID()}
	return &wfStruct, nil
}

func (c *TemporalWF) Terminate(ctx context.Context, req *workflows.TerminateRequest) error {
	c.logger.Debugf("terminating workflow")

	err := c.client.TerminateWorkflow(ctx, req.InstanceID, "", "")
	if err != nil {
		return fmt.Errorf("error terminating workflow: %w", err)
	}
	return nil
}

func (c *TemporalWF) Get(ctx context.Context, req *workflows.GetRequest) (*workflows.StateResponse, error) {
	c.logger.Debugf("getting workflow data")
	resp, err := c.client.DescribeWorkflowExecution(ctx, req.InstanceID, "")
	if err != nil {
		return nil, err
	}

	var createdAtTime time.Time
	if resp.WorkflowExecutionInfo.StartTime != nil {
		createdAtTime = *resp.WorkflowExecutionInfo.StartTime
	}

	// Build the output struct
	outputStruct := workflows.StateResponse{
		Workflow: &workflows.WorkflowState{
			InstanceID:    req.InstanceID,
			CreatedAt:     createdAtTime,
			LastUpdatedAt: createdAtTime,
			RuntimeStatus: lookupStatus(resp.WorkflowExecutionInfo.Status),
			Properties: map[string]string{
				"task_queue": resp.WorkflowExecutionInfo.GetTaskQueue(),
			},
		},
	}

	return &outputStruct, nil
}

func (c *TemporalWF) RaiseEvent(ctx context.Context, req *workflows.RaiseEventRequest) error {
	var decodedEventData interface{}
	if err := decodeInputData(req.EventData, &decodedEventData); err != nil {
		return fmt.Errorf("error decoding workflow event data: %w", err)
	}
	return c.client.SignalWorkflow(ctx, req.InstanceID, "", req.EventName, decodedEventData)
}

func (c *TemporalWF) Purge(ctx context.Context, req *workflows.PurgeRequest) error {
	// Unimplemented
	return nil
}

func (c *TemporalWF) Close() {
	c.client.Close()
}

func (c *TemporalWF) Pause(ctx context.Context, req *workflows.PauseRequest) error {
	return workflows.ErrNotImplemented
}

func (c *TemporalWF) Resume(ctx context.Context, req *workflows.ResumeRequest) error {
	return workflows.ErrNotImplemented
}

func (c *TemporalWF) parseMetadata(meta workflows.Metadata) (*temporalMetadata, error) {
	var m temporalMetadata
	err := metadata.DecodeMetadata(meta.Properties, &m)
	return &m, err
}

func (c *TemporalWF) GetComponentMetadata() (metadataInfo metadata.MetadataMap) {
	metadataStruct := temporalMetadata{}
	metadata.GetMetadataInfoFromStructType(reflect.TypeOf(metadataStruct), &metadataInfo, metadata.WorkflowType)
	return
}

func lookupStatus(status enums.WorkflowExecutionStatus) string {
	switch status {
	case 0:
		return "Unspecified"
	case 1:
		return "Running"
	case 2:
		return "Completed"
	case 3:
		return "Failed"
	case 4:
		return "Canceled"
	case 5:
		return "Terminated"
	case 6:
		return "ContinuedAsNew"
	case 7:
		return "TimedOut"
	default:
		return "status unknown"
	}
}

func decodeInputData(data []byte, result interface{}) error {
	if len(data) == 0 {
		return nil
	}

	// NOTE: We assume all inputs are JSON values
	return json.Unmarshal(data, result)
}