package runnermanager

import (
	"context"
	"fmt"
	"strings"
	"time"

	"github.com/op/go-logging"
	"google.golang.org/protobuf/proto"
	"nhooyr.io/websocket"

	"git.ohea.xyz/cursorius/server/config"

	runner_api "git.ohea.xyz/cursorius/runner-api/go/api/v2"
)

var log = logging.MustGetLogger("cursorius-server")

type RunnerRegistration struct {
	Secret string
	Id     string
	Tags   []string
	conn   *websocket.Conn
}

type runnerManager struct {
	getRunnerCh         chan GetRunnerRequest
	registerCh          chan RunnerRegistration
	connectedRunners    []Runner
	numConnectedRunners uint64
	configuredRunners   map[string]config.Runner
}

type GetRunnerRequest struct {
	Tags     []string
	RespChan chan GetRunnerResponse
}

type GetRunnerResponse struct {
	Runner *Runner
	Err    error
}

type runnerJob struct {
	Id  string
	URL string
}

func (r *runnerManager) processRequest(req GetRunnerRequest) {
	var runnerTagsStr strings.Builder
	fmt.Fprintf(&runnerTagsStr, "[%v", req.Tags[0])
	for _, tag := range req.Tags[1:] {
		fmt.Fprintf(&runnerTagsStr, ", %v", tag)
	}
	fmt.Fprintf(&runnerTagsStr, "]")
	log.Infof("Got request for runner with tags \"%v\"", runnerTagsStr.String())

	log.Debugf("Finding runner with tags %v", runnerTagsStr.String())

	foundRunner := false

	runnersToRemove := []int{}
runnerIter:
	for i, runner := range r.connectedRunners {
		// don't allocate runner that is already occupied
		if runner.running {
			log.Debugf("Skipping runner %v, as runner is activly running another job", runner.id)
			continue
		}
		// don't allocate runner with closed receiveChan (is defunct)
		// there should never be messages to read on an inactive runner,
		// so we aren't losing any data here
		select {
		case _, ok := <-runner.receiveChan:
			if ok {
				// this should never happen
				// TODO: should we disconnect the runner?
				log.Errorf("Recieved data from inactive runner %v, this is a bug", runner.id)
				continue
			}
			log.Noticef("Removing defunct runner \"%v\"", runner.id)
			runnersToRemove = append(runnersToRemove, i)
		default:
			log.Debugf("Checking runner %v for requested tags", runner.id)

		tagIter:
			for _, requestedTag := range req.Tags {
				for _, posessedTag := range runner.tags {
					if requestedTag == posessedTag {
						continue tagIter
					}
				}
				continue runnerIter
			}

			r.connectedRunners[i].running = true
			foundRunner = true
			req.RespChan <- GetRunnerResponse{
				Runner: &r.connectedRunners[i],
				Err:    nil,
			}
		}

	}
	// since we iterate, all the indexes will be in accending order
	for i, runnerInd := range runnersToRemove {
		r.connectedRunners[runnerInd-i] = r.connectedRunners[len(r.connectedRunners)-1]
		r.connectedRunners = r.connectedRunners[0 : len(r.connectedRunners)-2]
	}

	if foundRunner {
		return
	}

	errorMsg := "could not find valid runner"
	if len(r.connectedRunners) == 0 {
		errorMsg = "no connected runners"
	}
	req.RespChan <- GetRunnerResponse{
		Runner: &Runner{},
		Err:    fmt.Errorf("Could not allocate runner: %v", errorMsg),
	}

}

func (r *runnerManager) processRegistration(reg RunnerRegistration) {
	log.Debugf("New runner appeared with id: %v and secret: %v", reg.Id, reg.Secret)
	if configuredRunner, doesExist := r.configuredRunners[reg.Id]; doesExist {
		if configuredRunner.Secret == reg.Secret {
			log.Infof("Registering runner \"%v\" with tags %v", reg.Id, reg.Tags)
			runner := Runner{
				id:          reg.Id,
				tags:        reg.Tags,
				conn:        reg.conn,
				receiveChan: make(chan []byte),
				running:     false,
			}
			r.connectedRunners = append(r.connectedRunners, runner)
			// start goroutine to call Read function on websocket connection
			// this is required to keep the connection functioning
			go func() {
				defer log.Noticef("Deregistered runner with id: %v", runner.id)
				defer close(runner.receiveChan)
				for {
					msgType, data, err := reg.conn.Read(context.Background())
					if err != nil {
						// TODO: this is still racy, since a runner could be allocated between the
						// connection returning an err and the channel closing
						// This should probably be handled by sending erroring, but not 100% sure
						log.Errorf("Could not read from connection: %v", err)
						return
					}
					if msgType != websocket.MessageBinary {
						close(runner.receiveChan)
						log.Errorf("Got binary data from connection")
						return
					}

					runner.receiveChan <- data

				}
			}()

		} else {
			log.Errorf("Disconnecting runner with id: %v and invalid secret: %v", reg.Id, reg.Secret)
			reg.conn.Close(websocket.StatusNormalClosure, "registration invalid")
		}
	} else {
		log.Errorf("Disconnecting runner with invalid id: %v", reg.Id)
		reg.conn.Close(websocket.StatusNormalClosure, "registration invalid")
	}
}

func runRunnerManager(r runnerManager) {
	for {
		select {
		case request := <-r.getRunnerCh:
			r.processRequest(request)

		case registration := <-r.registerCh:
			r.processRegistration(registration)
		}
	}
}

func StartRunnerManager(configuredRunners map[string]config.Runner) (chan GetRunnerRequest, chan RunnerRegistration, error) {
	scheduler := runnerManager{
		getRunnerCh:       make(chan GetRunnerRequest),
		registerCh:        make(chan RunnerRegistration),
		connectedRunners:  make([]Runner, 0),
		configuredRunners: configuredRunners,
	}

	go runRunnerManager(scheduler)

	return scheduler.getRunnerCh, scheduler.registerCh, nil
}

func RegisterRunner(conn *websocket.Conn, registerCh chan RunnerRegistration) {
	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
	defer cancel()

	var registration RunnerRegistration
	registration.conn = conn

	typ, r, err := conn.Read(ctx)
	if err != nil {
		log.Errorf("Could not read from runner websocket connection: %v", err)
		log.Errorf("Disconnecting...")
		return
	}
	if typ != websocket.MessageBinary {
		log.Error("Got non binary message from runner, disconnecting...")
		conn.Close(websocket.StatusUnsupportedData, "Requires binary data")
		return
	}
	registration_proto := &runner_api.Register{}
	if err := proto.Unmarshal(r, registration_proto); err != nil {
		log.Error("Could not parse registration message from runner, disconnection....")
		conn.Close(websocket.StatusUnsupportedData, "Invalid message")
		return
	}

	registration.Secret = registration_proto.Secret
	registration.Id = registration_proto.Id
	registration.Tags = registration_proto.Tags

	registerCh <- registration
}