package task_runner

import (
	"database/sql"
	"fmt"
	"math"
	"os"
	"runtime/debug"
	"time"

	"github.com/charmbracelet/log"

	. "git.andr3h3nriqu3s.com/andr3/fyp/logic/db_types"
	. "git.andr3h3nriqu3s.com/andr3/fyp/logic/models"
	. "git.andr3h3nriqu3s.com/andr3/fyp/logic/models/train"
	. "git.andr3h3nriqu3s.com/andr3/fyp/logic/tasks/utils"
	. "git.andr3h3nriqu3s.com/andr3/fyp/logic/users"
	. "git.andr3h3nriqu3s.com/andr3/fyp/logic/utils"
)

/**
* Actually runs the code
 */
func runner(config Config, db *sql.DB, task_channel chan Task, index int, back_channel chan int) {
	logger := log.NewWithOptions(os.Stdout, log.Options{
		ReportCaller:    true,
		ReportTimestamp: true,
		TimeFormat:      time.Kitchen,
		Prefix:          fmt.Sprintf("Runner %d", index),
	})

	defer func() {
		if r := recover(); r != nil {
			logger.Error("Recovered in runner", "processor id", index, "due to", r, "stack", string(debug.Stack()))
			back_channel <- -index
		}
	}()

	logger.Info("Started up")

	var err error

	base := BasePackStruct{
		Db:     db,
		Logger: logger,
		Host:   config.Hostname,
	}

	for task := range task_channel {
		logger.Info("Got task", "task", task)
		task.UpdateStatusLog(base, TASK_PICKED_UP, "Runner picked up task")

		if task.TaskType == int(TASK_TYPE_CLASSIFICATION) {
			logger.Info("Classification Task")
			if err = ClassifyTask(base, task); err != nil {
				logger.Error("Classification task failed", "error", err)
			}

			back_channel <- index
			continue
		} else if task.TaskType == int(TASK_TYPE_TRAINING) {
			logger.Info("Training Task")
			if err = RunTaskTrain(base, task); err != nil {
				logger.Error("Failed to tain the model", "error", err)
			}

			back_channel <- index
			continue
		} else if task.TaskType == int(TASK_TYPE_RETRAINING) {
			logger.Info("Retraining Task")
			if err = RunTaskRetrain(base, task); err != nil {
				logger.Error("Failed to tain the model", "error", err)
			}

			back_channel <- index
			continue
		} else if task.TaskType == int(TASK_TYPE_DELETE_USER) {
			logger.Warn("User deleting Task")
			if err = DeleteUser(base, task); err != nil {
				logger.Error("Failed to tain the model", "error", err)
			}

			back_channel <- index
			continue
		}

		logger.Error("Do not know how to route task", "task", task)
		task.UpdateStatusLog(base, TASK_FAILED_RUNNING, "Do not know how to route task")
		back_channel <- index
	}
}

/**
* Tells the orcchestator to look at the task list from time to time
 */
func attentionSeeker(config Config, back_channel chan int) {
	logger := log.NewWithOptions(os.Stdout, log.Options{
		ReportCaller:    true,
		ReportTimestamp: true,
		TimeFormat:      time.Kitchen,
		Prefix:          "Runner Orchestrator Logger [Attention]",
	})

	defer func() {
		if r := recover(); r != nil {
			logger.Error("Attencion seeker dies", "due to", r)
		}
	}()

	logger.Info("Started up")

	t, err := time.ParseDuration(config.GpuWorker.Pulling)
	if err != nil {
		logger.Error("Failed to load", "error", err)
		return
	}

	for true {
		back_channel <- 0

		time.Sleep(t)
	}
}

/**
* Manages what worker should to Work
 */
func RunnerOrchestrator(db *sql.DB, config Config) {
	logger := log.NewWithOptions(os.Stdout, log.Options{
		ReportCaller:    true,
		ReportTimestamp: true,
		TimeFormat:      time.Kitchen,
		Prefix:          "Runner Orchestrator Logger",
	})

	gpu_workers := config.GpuWorker.NumberOfWorkers

	logger.Info("Starting runners")

	task_runners := make([]chan Task, gpu_workers)
	task_runners_used := make([]bool, gpu_workers)
	// One more to accomudate the Attention Seeker channel
	back_channel := make(chan int, gpu_workers+1)

	defer func() {
		if r := recover(); r != nil {
			logger.Error("Recovered in Orchestrator restarting", "due to", r)
			for x := range task_runners {
				close(task_runners[x])
			}
			close(back_channel)
			go RunnerOrchestrator(db, config)
		}
	}()

	go attentionSeeker(config, back_channel)

	// Start the runners
	for i := 0; i < gpu_workers; i++ {
		task_runners[i] = make(chan Task, 10)
		task_runners_used[i] = false
		go runner(config, db, task_runners[i], i+1, back_channel)
	}

	var task_to_dispatch *Task = nil

	for i := range back_channel {

		if i > 0 {
			logger.Info("Runner freed", "runner", i)
			task_runners_used[i-1] = false
		} else if i < 0 {
			logger.Error("Runner died! Restarting!", "runner", i)
			i = int(math.Abs(float64(i)) - 1)
			task_runners_used[i] = false
			go runner(config, db, task_runners[i], i+1, back_channel)
		}

		if task_to_dispatch == nil {
			var task TaskT
			err := GetDBOnce(db, &task, "tasks as t "+
				// Get depenencies
				"left join tasks_dependencies as td on t.id=td.main_id "+
				// Get the task that the depencey resolves to
				"left join tasks as t2 on t2.id=td.dependent_id "+
				"where t.status=1 "+
				"group by t.id having count(td.id) filter (where t2.status in (0,1,2,3)) = 0;")
			if err != NotFoundError && err != nil {
				log.Error("Failed to get tasks from db", "err", err)
				continue
			}
			if err == NotFoundError {
				task_to_dispatch = nil
			} else {
				temp := Task(task)
				task_to_dispatch = &temp
			}
		}

		if task_to_dispatch != nil {
			for i := 0; i < len(task_runners_used); i += 1 {
				if !task_runners_used[i] {
					task_runners[i] <- *task_to_dispatch
					task_runners_used[i] = true
					task_to_dispatch = nil
					break
				}
			}
		}

	}
}

func StartRunners(db *sql.DB, config Config) {
	go RunnerOrchestrator(db, config)
}