package api_impl

// SPDX-License-Identifier: GPL-3.0-or-later

import (
	"context"
	"errors"
	"fmt"
	"net/http"

	"github.com/gertd/go-pluralize"
	"github.com/labstack/echo/v4"
	"github.com/rs/zerolog"

	"git.blender.org/flamenco/internal/manager/persistence"
	"git.blender.org/flamenco/internal/uuid"
	"git.blender.org/flamenco/pkg/api"
)

func (f *Flamenco) TaskUpdate(e echo.Context, taskID string) error {
	logger := requestLogger(e)
	worker := requestWorkerOrPanic(e)

	if !uuid.IsValid(taskID) {
		logger.Debug().Msg("invalid task ID received")
		return sendAPIError(e, http.StatusBadRequest, "task ID not valid")
	}
	logger = logger.With().Str("taskID", taskID).Logger()

	// Fetch the task, to see if this worker is even allowed to send us updates.
	ctx := e.Request().Context()
	dbTask, err := f.persist.FetchTask(ctx, taskID)
	if err != nil {
		logger.Warn().Err(err).Msg("cannot fetch task")
		if errors.Is(err, persistence.ErrTaskNotFound) {
			return sendAPIError(e, http.StatusNotFound, "task %+v not found", taskID)
		}
		return sendAPIError(e, http.StatusInternalServerError, "error fetching task")
	}
	if dbTask == nil {
		panic("task could not be fetched, but database gave no error either")
	}

	// Decode the request body.
	var taskUpdate api.TaskUpdate
	if err := e.Bind(&taskUpdate); err != nil {
		logger.Warn().Err(err).Msg("bad request received")
		return sendAPIError(e, http.StatusBadRequest, "invalid format")
	}
	if dbTask.WorkerID == nil {
		logger.Warn().
			Msg("worker trying to update task that's not assigned to any worker")
		return sendAPIError(e, http.StatusConflict, "task %+v is not assigned to any worker, so also not to you", taskID)
	}
	if *dbTask.WorkerID != worker.ID {
		logger.Warn().Msg("worker trying to update task that's assigned to another worker")
		return sendAPIError(e, http.StatusConflict, "task %+v is not assigned to you", taskID)
	}

	// Status 'soft-failed' should never be sent by a Worker. Distinguishing
	// between soft and hard failures is up to the Manager.
	// Workers should always just send 'failed' instead.
	if taskUpdate.TaskStatus != nil && *taskUpdate.TaskStatus == api.TaskStatusSoftFailed {
		logger.Warn().Str("status", string(*taskUpdate.TaskStatus)).
			Msg("worker trying to update task to not-allowed status")
		return sendAPIError(e, http.StatusBadRequest,
			"task status %s not allowed to be sent by Worker", *taskUpdate.TaskStatus)
	}

	taskUpdateErr := f.doTaskUpdate(ctx, logger, worker, dbTask, taskUpdate)
	workerUpdateErr := f.workerPingedTask(ctx, logger, dbTask)
	workerSeenErr := f.workerSeen(ctx, logger, worker)

	if taskUpdateErr != nil {
		return sendAPIError(e, http.StatusInternalServerError, "unable to handle task update: %v", taskUpdateErr)
	}
	if workerUpdateErr != nil {
		return sendAPIError(e, http.StatusInternalServerError, "unable to handle worker update: %v", workerUpdateErr)
	}
	if workerSeenErr != nil {
		return sendAPIError(e, http.StatusInternalServerError, "unable to handle worker 'last seen' update: %v", workerSeenErr)
	}

	return e.NoContent(http.StatusNoContent)
}

// doTaskUpdate actually updates the task and its log file.
func (f *Flamenco) doTaskUpdate(
	ctx context.Context,
	logger zerolog.Logger,
	w *persistence.Worker,
	dbTask *persistence.Task,
	update api.TaskUpdate,
) error {
	if dbTask.Job == nil {
		logger.Panic().Msg("dbTask.Job is nil, unable to continue")
	}

	var dbErrActivity error

	if update.Activity != nil {
		dbTask.Activity = *update.Activity
		// The state machine will also save the task, including its activity, but
		// relying on that here would create strong cohesion.
		dbErrActivity = f.persist.SaveTaskActivity(ctx, dbTask)
	}

	// Write the log first, because that's likely to contain the cause of the task
	// state change. Any subsequent task logs, for example generated by the
	// Manager in response to a status change, should be logged after that.
	if update.Log != nil {
		// Errors writing the log to disk are already logged by logStorage, and can be safely ignored here.
		_ = f.logStorage.Write(logger, dbTask.Job.UUID, dbTask.UUID, *update.Log)
	}

	if update.TaskStatus == nil {
		return dbErrActivity
	}

	oldTaskStatus := dbTask.Status
	var err error
	if *update.TaskStatus == api.TaskStatusFailed {
		// Failure is more complex than just going to the failed state.
		err = f.onTaskFailed(ctx, logger, w, dbTask, update)
	} else {
		// Just go to the given state.
		err = f.stateMachine.TaskStatusChange(ctx, dbTask, *update.TaskStatus)
	}

	if err != nil {
		logger.Error().Err(err).
			Str("newTaskStatus", string(*update.TaskStatus)).
			Str("oldTaskStatus", string(oldTaskStatus)).
			Msg("error changing task status")
		return fmt.Errorf("changing status of task %s to %q: %w",
			dbTask.UUID, *update.TaskStatus, err)
	}

	return nil
}

// onTaskFailed decides whether a task is soft- or hard-failed. Note that this
// means that the task may NOT go to the status mentioned in the `update`
// parameter, but go to `soft-failed` instead.
func (f *Flamenco) onTaskFailed(
	ctx context.Context,
	logger zerolog.Logger,
	worker *persistence.Worker,
	task *persistence.Task,
	update api.TaskUpdate,
) error {
	// Sanity check.
	if update.TaskStatus == nil || *update.TaskStatus != api.TaskStatusFailed {
		panic("onTaskFailed should only be called with a task update that indicates task failure")
	}

	// Bookkeeping of failure.
	numFailed, err := f.persist.AddWorkerToTaskFailedList(ctx, task, worker)
	if err != nil {
		return fmt.Errorf("adding worker to failure list of task: %w", err)
	}
	// f.maybeBlocklistWorker(ctx, logger, worker, task)

	// Determine whether this is soft or hard failure.
	threshold := f.config.Get().TaskFailAfterSoftFailCount
	logger = logger.With().
		Int("failedByWorkerCount", numFailed).
		Int("threshold", threshold).
		Logger()

	var (
		newStatus         api.TaskStatus
		localLog, taskLog string
	)
	pluralizer := pluralize.NewClient()
	if numFailed >= threshold {
		newStatus = api.TaskStatusFailed

		localLog = "too many workers failed this task, hard-failing it"
		taskLog = fmt.Sprintf(
			"Task failed by %s, Manager will mark it as hard failure",
			pluralizer.Pluralize("worker", numFailed, true),
		)
	} else {
		newStatus = api.TaskStatusSoftFailed

		localLog = "worker failed this task, soft-failing to give another worker a try"
		failsToThreshold := threshold - numFailed
		taskLog = fmt.Sprintf(
			"Task failed by %s, Manager will mark it as soft failure. %d more %s will cause hard failure.",
			pluralizer.Pluralize("worker", numFailed, true),
			failsToThreshold,
			pluralizer.Pluralize("failure", failsToThreshold, false),
		)
	}

	if err := f.logStorage.WriteTimestamped(logger, task.Job.UUID, task.UUID, taskLog); err != nil {
		logger.Error().Err(err).Msg("error writing failure notice to task log")
	}

	logger.Info().Str("newTaskStatus", string(newStatus)).Msg(localLog)
	return f.stateMachine.TaskStatusChange(ctx, task, newStatus)
}