package worker

import (
	"context"
	"errors"
	"fmt"
	"sync"
	"time"
)

type (
	// Task should watch for context
	Task interface {
		Start(context.Context) error
	}

	Work struct {
		Name string
		Task Task
		wait time.Duration
	}

	TaskPool struct {
		tasks []*Work
	}
)

const (
	format = "2006.01.02 15:04:05"
)

func NewTaskPool() *TaskPool {
	return &TaskPool{}
}

func (w *Work) run(ctx context.Context) error {
	// first time fire from the get go
	timer := time.NewTimer(time.Nanosecond)

	for {
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-timer.C:
			now := time.Now()
			fmt.Printf("[%s] Process starting: %s\n", time.Now().Format(format), w.Name)
			if err := w.Task.Start(ctx); err != nil && !errors.Is(err, context.Canceled) {
				since := time.Since(now)
				fmt.Printf("[%s] Process errored (%s): %s\n", time.Now().Format(format), since.String(), w.Name)
				return err
			} else {
				since := time.Since(now)
				fmt.Printf("[%s] Process done (%s): %s\n", time.Now().Format(format), since.String(), w.Name)
			}
		}
		timer.Reset(w.wait)
	}
}

func (self *TaskPool) AddTask(name string, wait time.Duration, task Task) {
	self.tasks = append(self.tasks, &Work{
		Name: name,
		Task: task,
		wait: wait,
	})
}

func (self *TaskPool) Start(ctx context.Context) {
	var wg sync.WaitGroup

	wg.Add(len(self.tasks))

	for _, w := range self.tasks {
		go func(w *Work) {
			_ = w.run(ctx)
			wg.Done()
		}(w)
	}

	wg.Wait()
}