package runnermanager

import (
	"context"
	"fmt"
	"time"

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

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

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

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

func (r *runnerManager) processRunnerAllocation(req RunnerAllocationRequest) {
	tagsStr := util.FormatTags(req.Tags)
	log.Infof("Got request for runner with tags \"%v\"", tagsStr)

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

	foundRunner := false

	runnersToRemove := []int{}
runnerIter:
	for i, runner := range r.connectedRunners {
		// 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)

			if !runner.HasTags(req.Tags) {
				continue runnerIter
			}

			runnersToRemove = append(runnersToRemove, i)
			foundRunner = true
			log.Debugf("Runner %v has requested tags, allocating", runner.id)
			req.RespChan <- RunnerAllocationResponse{
				Runner: &r.connectedRunners[i],
				Err:    nil,
			}
		}

	}
	// remove allocated runner plus defunct runners
	// 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)-1]
	}

	if foundRunner {
		return
	}

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

}

func (r *runnerManager) processRunnerRegistration(req RunnerRegistrationRequest) {
	log.Debugf("New runner appeared with id: %v and secret: %v", req.Id, req.Secret)

	// Get runner with give id from database
	runnerId, err := uuid.Parse(req.Id)
	if err != nil {
		log.Errorf("Disconnecting runner with id: %v, could not parse as UUID: %v", req.Id, err)
		req.conn.Close(websocket.StatusNormalClosure, "registration invalid")
		return
	}
	dbRunner, err := r.db.GetRunnerById(runnerId)
	if err != nil {
		log.Errorf("Disconnecting runner with id: %v, could not find runner in DB: %v", runnerId, err)
		req.conn.Close(websocket.StatusNormalClosure, "registration invalid")
		return
	}

	if req.Secret != dbRunner.Token {
		log.Errorf("Disconnecting runner with id: %v, invalid secret", runnerId)
		req.conn.Close(websocket.StatusNormalClosure, "registration invalid")
		return
	}

	log.Infof("Registering runner \"%v\" with tags %v", req.Id, req.Tags)
	runner := Runner{
		id:          runnerId,
		tags:        req.Tags,
		conn:        req.conn,
		receiveChan: make(chan []byte),
	}
	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 := req.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

		}
	}()
}

func (r *runnerManager) processRunnerRelease(req RunnerReleaseRequest) {
	r.connectedRunners = append(r.connectedRunners, *req.Runner)
}

func runRunnerManager(r runnerManager) {
	for {
		select {
		case request := <-r.chans.Allocation:
			r.processRunnerAllocation(request)
		case release := <-r.chans.Release:
			r.processRunnerRelease(release)
		case registration := <-r.chans.Registration:
			r.processRunnerRegistration(registration)
		}
	}
}

func StartRunnerManager(configuredRunners map[string]config.Runner, db database.Database) (RunnerManagerChans, error) {
	scheduler := runnerManager{
		chans: RunnerManagerChans{
			Allocation:   make(chan RunnerAllocationRequest),
			Release:      make(chan RunnerReleaseRequest),
			Registration: make(chan RunnerRegistrationRequest),
		},
		connectedRunners:  make([]Runner, 0),
		configuredRunners: configuredRunners,
		db:                db,
	}

	go runRunnerManager(scheduler)

	return scheduler.chans, nil
}

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

	var registration RunnerRegistrationRequest
	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
}