package executor

import (
	pb "github.com/OliveTin/OliveTin/gen/grpc"
	acl "github.com/OliveTin/OliveTin/internal/acl"
	config "github.com/OliveTin/OliveTin/internal/config"
	"github.com/google/uuid"
	log "github.com/sirupsen/logrus"

	"bytes"
	"context"
	"io"
	"os/exec"
	"runtime"
	"time"
)

// ExecutionRequest is a request to execute an action. It's passed to an
// Executor. They're created from the grpcapi.
type ExecutionRequest struct {
	ActionName         string
	Arguments          map[string]string
	Tags               []string
	action             *config.Action
	Cfg                *config.Config
	AuthenticatedUser  *acl.AuthenticatedUser
	logEntry           *InternalLogEntry
	finalParsedCommand string
	uuid               string
}

// InternalLogEntry objects are created by an Executor, and represent the final
// state of execution (even if the command is not executed). It's designed to be
// easily serializable.
type InternalLogEntry struct {
	DatetimeStarted  string
	DatetimeFinished string
	Stdout           string
	Stderr           string
	StdoutBuffer     io.ReadCloser
	StderrBuffer     io.ReadCloser
	TimedOut         bool
	ExitCode         int32
	Tags             []string

	/*
		The following two properties are obviously on Action normally, but it's useful
		that logs are lightweight (so we don't need to have an action associated to
		logs, etc. Therefore, we duplicate those values here.
	*/
	ActionTitle string
	ActionIcon  string

	ExecutionStarted   bool
	ExecutionCompleted bool
}

type executorStepFunc func(*ExecutionRequest) bool

// Executor represents a helper class for executing commands. It's main method
// is ExecRequest
type Executor struct {
	Logs map[string]*InternalLogEntry

	chainOfCommand []executorStepFunc
}

// DefaultExecutor returns an Executor, with a sensible "chain of command" for
// executing actions.
func DefaultExecutor() *Executor {
	e := Executor{}
	e.Logs = make(map[string]*InternalLogEntry)

	e.chainOfCommand = []executorStepFunc{
		stepFindAction,
		stepACLCheck,
		stepParseArgs,
		stepLogStart,
		stepExec,
		stepLogFinish,
	}

	return &e
}

// ExecRequest processes an ExecutionRequest
func (e *Executor) ExecRequest(req *ExecutionRequest) *pb.StartActionResponse {
	req.uuid = uuid.New().String()
	req.logEntry = &InternalLogEntry{
		DatetimeStarted:    time.Now().Format("2006-01-02 15:04:05"),
		ActionTitle:        req.ActionName,
		Stdout:             "",
		Stderr:             "",
		ExitCode:           -1337, // If an Action is not actually executed, this is the default exit code.
		ExecutionStarted:   false,
		ExecutionCompleted: false,
	}

	e.Logs[req.uuid] = req.logEntry

	go e.execChain(req)

	return &pb.StartActionResponse{
		ExecutionUuid: req.uuid,
	}
}

func (e *Executor) execChain(req *ExecutionRequest) {
	for _, step := range e.chainOfCommand {
		if !step(req) {
			break
		}
	}
}

func stepFindAction(req *ExecutionRequest) bool {
	actualAction := req.Cfg.FindAction(req.ActionName)

	if actualAction == nil {
		log.WithFields(log.Fields{
			"actionName": req.ActionName,
		}).Warnf("Action not found")

		req.logEntry.Stderr = "Action not found"

		return false
	}

	req.action = actualAction
	req.logEntry.ActionIcon = actualAction.Icon

	return true
}

func stepACLCheck(req *ExecutionRequest) bool {
	return acl.IsAllowedExec(req.Cfg, req.AuthenticatedUser, req.action)
}

func stepParseArgs(req *ExecutionRequest) bool {
	var err error

	req.finalParsedCommand, err = parseActionArguments(req.action.Shell, req.Arguments, req.action)

	if err != nil {
		req.logEntry.Stdout = err.Error()

		log.Warnf(err.Error())

		return false
	}

	return true
}

func stepLogStart(req *ExecutionRequest) bool {
	log.WithFields(log.Fields{
		"title":   req.action.Title,
		"timeout": req.action.Timeout,
	}).Infof("Action starting")

	return true
}

func stepLogFinish(req *ExecutionRequest) bool {
	log.WithFields(log.Fields{
		"title":    req.action.Title,
		"stdout":   req.logEntry.Stdout,
		"stderr":   req.logEntry.Stderr,
		"timedOut": req.logEntry.TimedOut,
		"exit":     req.logEntry.ExitCode,
	}).Infof("Action finished")

	return true
}

func wrapCommandInShell(ctx context.Context, finalParsedCommand string) *exec.Cmd {
	if runtime.GOOS == "windows" {
		return exec.CommandContext(ctx, "cmd", "/C", finalParsedCommand)
	}

	return exec.CommandContext(ctx, "sh", "-c", finalParsedCommand)
}

func stepExec(req *ExecutionRequest) bool {
	ctx, cancel := context.WithTimeout(context.Background(), time.Duration(req.action.Timeout)*time.Second)
	defer cancel()

	var stdout bytes.Buffer
	var stderr bytes.Buffer

	cmd := wrapCommandInShell(ctx, req.finalParsedCommand)
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr
	req.logEntry.StdoutBuffer, _ = cmd.StdoutPipe()
	req.logEntry.StderrBuffer, _ = cmd.StderrPipe()

	req.logEntry.ExecutionStarted = true

	runerr := cmd.Start()

	cmd.Wait()

	// req.logEntry.Stdout = req.logEntry.StdoutBuffer.String()
	// req.logEntry.Stderr = req.logEntry.StderrBuffer.String()

	req.logEntry.ExecutionCompleted = true
	req.logEntry.ExitCode = int32(cmd.ProcessState.ExitCode())
	req.logEntry.Stdout = stdout.String()
	req.logEntry.Stderr = stderr.String()

	if runerr != nil {
		req.logEntry.Stderr = runerr.Error() + "\n\n" + req.logEntry.Stderr
	}

	if ctx.Err() == context.DeadlineExceeded {
		req.logEntry.TimedOut = true
	}

	req.logEntry.Tags = req.Tags

	return true
}