package task

import (
	"context"
	"errors"
	"fmt"
	"time"

	"github.com/influxdata/platform"
	"github.com/influxdata/platform/task/backend"
	"github.com/influxdata/platform/task/options"
)

// PlatformAdapter wraps a task.Store into the platform.TaskService interface.
func PlatformAdapter(s backend.Store, r backend.LogReader) platform.TaskService {
	return pAdapter{s: s, r: r}
}

type pAdapter struct {
	s backend.Store
	r backend.LogReader
}

var _ platform.TaskService = pAdapter{}

func (p pAdapter) FindTaskByID(ctx context.Context, id platform.ID) (*platform.Task, error) {
	t, err := p.s.FindTaskByID(ctx, id)
	if err != nil {
		return nil, err
	}

	// The store interface specifies that a returned task is nil if the operation succeeded without a match.
	if t == nil {
		return nil, nil
	}

	return toPlatformTask(*t)
}

func (p pAdapter) FindTasks(ctx context.Context, filter platform.TaskFilter) ([]*platform.Task, int, error) {
	const pageSize = 100 // According to the platform.TaskService.FindTasks API.

	params := backend.TaskSearchParams{PageSize: pageSize}
	if filter.Organization != nil {
		params.Org = *filter.Organization
	}
	if filter.User != nil {
		params.User = *filter.User
	}
	if filter.After != nil {
		params.After = *filter.After
	}
	ts, err := p.s.ListTasks(ctx, params)
	if err != nil {
		return nil, 0, err
	}

	pts := make([]*platform.Task, len(ts))
	for i, t := range ts {
		pts[i], err = toPlatformTask(t)
		if err != nil {
			return nil, 0, err
		}
	}

	totalResults := len(pts) // TODO(mr): don't lie about the total results. Update ListTasks signature?
	return pts, totalResults, nil
}

func (p pAdapter) CreateTask(ctx context.Context, t *platform.Task) error {
	opts, err := options.FromScript(t.Flux)
	if err != nil {
		return err
	}

	// TODO(mr): decide whether we allow user to configure scheduleAfter. https://github.com/influxdata/platform/issues/595
	scheduleAfter := time.Now().Unix()
	id, err := p.s.CreateTask(ctx, t.Organization, t.Owner.ID, t.Flux, scheduleAfter)
	if err != nil {
		return err
	}
	t.ID = id
	t.Every = opts.Every.String()
	t.Cron = opts.Cron

	return nil
}

func (p pAdapter) UpdateTask(ctx context.Context, id platform.ID, upd platform.TaskUpdate) (*platform.Task, error) {
	if upd.Flux == nil && upd.Status == nil {
		return nil, errors.New("cannot update task without content")
	}

	task := &platform.Task{
		ID:     id,
		Name:   "TODO",
		Status: "TODO",
		Owner:  platform.User{}, // TODO(mr): populate from context?
	}
	if upd.Flux != nil {
		task.Flux = *upd.Flux

		opts, err := options.FromScript(task.Flux)
		if err != nil {
			return nil, err
		}
		task.Every = opts.Every.String()
		task.Cron = opts.Cron

		if err := p.s.ModifyTask(ctx, id, task.Flux); err != nil {
			return nil, err
		}
	}

	if upd.Status != nil {
		var err error
		switch *upd.Status {
		case string(backend.TaskEnabled):
			err = p.s.EnableTask(ctx, id)
		case string(backend.TaskDisabled):
			err = p.s.DisableTask(ctx, id)
		default:
			err = fmt.Errorf("invalid status: %s", *upd.Status)
		}

		if err != nil {
			return nil, err
		}
		task.Status = *upd.Status
	}

	return task, nil
}

func (p pAdapter) DeleteTask(ctx context.Context, id platform.ID) error {
	_, err := p.s.DeleteTask(ctx, id)
	// TODO(mr): Store.DeleteTask returns false, nil if ID didn't match; do we want to handle that case?
	return err
}

func (p pAdapter) FindLogs(ctx context.Context, filter platform.LogFilter) ([]*platform.Log, int, error) {
	logs, err := p.r.ListLogs(ctx, filter)
	logPointers := make([]*platform.Log, len(logs))
	for i := range logs {
		logPointers[i] = &logs[i]
	}
	return logPointers, len(logs), err
}

func (p pAdapter) FindRuns(ctx context.Context, filter platform.RunFilter) ([]*platform.Run, int, error) {
	runs, err := p.r.ListRuns(ctx, filter)
	return runs, len(runs), err
}

func (p pAdapter) FindRunByID(ctx context.Context, id platform.ID) (*platform.Run, error) {
	// TODO(lh): the inmem FindRunByID method doesnt need the taskId or orgId but we will need it PlatformAdapter
	// this call to the store is a filler until platform.TaskService gets the update to add the IDs
	return p.r.FindRunByID(ctx, platform.ID([]byte("replace")), platform.ID([]byte("replace")), id)
}

func (p pAdapter) RetryRun(ctx context.Context, id platform.ID) (*platform.Run, error) {
	return nil, errors.New("not yet implemented")
}

func toPlatformTask(t backend.StoreTask) (*platform.Task, error) {
	opts, err := options.FromScript(t.Script)
	if err != nil {
		return nil, err
	}

	pt := &platform.Task{
		ID:           t.ID,
		Organization: t.Org,
		Name:         t.Name,
		Status:       "", // TODO: set and update status
		Owner: platform.User{
			ID:   append([]byte(nil), t.User...), // Copy just in case.
			Name: "",                             // TODO(mr): how to get owner name?
		},
		Flux: t.Script,
		Cron: opts.Cron,
	}
	if opts.Every != 0 {
		pt.Every = opts.Every.String()
	}
	return pt, nil
}