package db

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"strings"
	"time"

	"github.com/cynfo/rmm-backend/models"
)

// CalculateNextRun computes the next run time based on schedule parameters.
func CalculateNextRun(scheduleType, scheduleTime string, weekday, monthday *int, after time.Time) time.Time {
	h, m := 2, 0
	fmt.Sscanf(scheduleTime, "%d:%d", &h, &m)

	loc := after.Location()

	switch scheduleType {
	case "daily":
		next := time.Date(after.Year(), after.Month(), after.Day(), h, m, 0, 0, loc)
		if !next.After(after) {
			next = next.AddDate(0, 0, 1)
		}
		return next

	case "weekly":
		wd := 1 // Monday default
		if weekday != nil {
			wd = *weekday
		}
		next := time.Date(after.Year(), after.Month(), after.Day(), h, m, 0, 0, loc)
		// Find next occurrence of weekday (0=Sun, 1=Mon, ..., 6=Sat)
		targetWd := time.Weekday(wd % 7)
		for next.Weekday() != targetWd || !next.After(after) {
			next = next.AddDate(0, 0, 1)
		}
		return next

	case "monthly":
		md := 1
		if monthday != nil {
			md = *monthday
		}
		if md < 1 {
			md = 1
		}
		if md > 28 {
			md = 28
		}
		next := time.Date(after.Year(), after.Month(), md, h, m, 0, 0, loc)
		if !next.After(after) {
			next = time.Date(after.Year(), after.Month()+1, md, h, m, 0, 0, loc)
		}
		return next

	default: // "once"
		return after
	}
}

func (d *Database) CreateTask(agentID, action, scheduledAt, webhookURL, createdBy string,
	name, scheduleType, scheduleTime string, weekday, monthday *int,
	reboot, healthCheck bool, healthCheckTimeout int, active bool) (*models.Task, error) {

	validActions := map[string]bool{"backup": true, "update": true}
	if !validActions[action] {
		return nil, fmt.Errorf("ungueltige Aktion: %s", action)
	}

	if scheduleType == "" {
		scheduleType = "once"
	}
	if scheduleTime == "" {
		scheduleTime = "02:00"
	}
	if healthCheckTimeout <= 0 {
		healthCheckTimeout = 600
	}

	now := time.Now()
	var schedTime time.Time

	if scheduleType == "once" {
		if scheduledAt == "" {
			schedTime = now
		} else {
			var err error
			schedTime, err = time.Parse(time.RFC3339, scheduledAt)
			if err != nil {
				return nil, fmt.Errorf("ungueltiges Datum: %w", err)
			}
		}
	} else {
		schedTime = now
	}

	var nextRun time.Time
	if scheduleType == "once" {
		nextRun = schedTime
	} else {
		nextRun = CalculateNextRun(scheduleType, scheduleTime, weekday, monthday, now)
	}

	var taskID int
	err := d.db.QueryRow(`
		INSERT INTO tasks (agent_id, name, action, scheduled_at, webhook_url, created_by,
			schedule_type, schedule_time, schedule_weekday, schedule_monthday,
			reboot, health_check, health_check_timeout, active, next_run)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15)
		RETURNING id
	`, agentID, name, action, schedTime, webhookURL, createdBy,
		scheduleType, scheduleTime, weekday, monthday,
		reboot, healthCheck, healthCheckTimeout, active, nextRun).Scan(&taskID)
	if err != nil {
		return nil, fmt.Errorf("Task erstellen: %w", err)
	}

	return d.GetTask(taskID)
}

func scanTask(scan func(dest ...interface{}) error) (*models.Task, error) {
	var t models.Task
	var scheduledAt, createdAt time.Time
	var startedAt, finishedAt, lastRun, nextRun sql.NullTime
	var resultJSON sql.NullString
	var webhookURL, webhookResponse, createdBy sql.NullString
	var agentName, customerName, customerNumber sql.NullString
	var name, scheduleType, scheduleTime sql.NullString
	var scheduleWeekday, scheduleMonthday sql.NullInt32
	var reboot, healthCheck, active sql.NullBool
	var healthCheckTimeout, runCount sql.NullInt32

	err := scan(
		&t.ID, &t.AgentID, &agentName, &customerName, &customerNumber,
		&name, &t.Action, &t.Status, &scheduledAt, &startedAt, &finishedAt,
		&resultJSON, &webhookURL, &t.WebhookSent, &webhookResponse,
		&createdBy, &createdAt,
		&scheduleType, &scheduleTime, &scheduleWeekday, &scheduleMonthday,
		&reboot, &healthCheck, &healthCheckTimeout, &active, &lastRun, &nextRun, &runCount,
	)
	if err != nil {
		return nil, err
	}

	t.AgentName = agentName.String
	t.CustomerName = customerName.String
	t.CustomerNumber = customerNumber.String
	t.Name = name.String
	t.ScheduleType = scheduleType.String
	if t.ScheduleType == "" {
		t.ScheduleType = "once"
	}
	t.ScheduleTime = scheduleTime.String
	if t.ScheduleTime == "" {
		t.ScheduleTime = "02:00"
	}
	if scheduleWeekday.Valid {
		v := int(scheduleWeekday.Int32)
		t.ScheduleWeekday = &v
	}
	if scheduleMonthday.Valid {
		v := int(scheduleMonthday.Int32)
		t.ScheduleMonthday = &v
	}
	t.Reboot = reboot.Valid && reboot.Bool
	t.HealthCheck = healthCheck.Valid && healthCheck.Bool
	t.HealthCheckTimeout = 600
	if healthCheckTimeout.Valid {
		t.HealthCheckTimeout = int(healthCheckTimeout.Int32)
	}
	t.Active = !active.Valid || active.Bool
	t.RunCount = int(runCount.Int32)

	t.ScheduledAt = scheduledAt.Format(time.RFC3339)
	t.CreatedAt = createdAt.Format(time.RFC3339)
	if startedAt.Valid {
		s := startedAt.Time.Format(time.RFC3339)
		t.StartedAt = &s
	}
	if finishedAt.Valid {
		s := finishedAt.Time.Format(time.RFC3339)
		t.FinishedAt = &s
	}
	if lastRun.Valid {
		s := lastRun.Time.Format(time.RFC3339)
		t.LastRun = &s
	}
	if nextRun.Valid {
		s := nextRun.Time.Format(time.RFC3339)
		t.NextRun = &s
	}
	if resultJSON.Valid {
		var r interface{}
		json.Unmarshal([]byte(resultJSON.String), &r)
		t.Result = r
	}
	if webhookURL.Valid {
		t.WebhookURL = webhookURL.String
	}
	if webhookResponse.Valid {
		t.WebhookResponse = webhookResponse.String
	}
	if createdBy.Valid {
		t.CreatedBy = createdBy.String
	}

	return &t, nil
}

const taskSelectCols = `t.id, t.agent_id, COALESCE(a.name, ''), COALESCE(c.name, ''), COALESCE(c.number, ''),
	t.name, t.action, t.status, t.scheduled_at, t.started_at, t.finished_at,
	t.result, t.webhook_url, t.webhook_sent, t.webhook_response,
	t.created_by, t.created_at,
	t.schedule_type, t.schedule_time, t.schedule_weekday, t.schedule_monthday,
	t.reboot, t.health_check, t.health_check_timeout, t.active, t.last_run, t.next_run, t.run_count`

const taskFromJoin = `FROM tasks t
	LEFT JOIN agents a ON a.id = t.agent_id
	LEFT JOIN customers c ON c.id = a.customer_id`

func (d *Database) GetTask(id int) (*models.Task, error) {
	row := d.db.QueryRow(fmt.Sprintf("SELECT %s %s WHERE t.id = $1", taskSelectCols, taskFromJoin), id)
	t, err := scanTask(row.Scan)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	return t, nil
}

func (d *Database) GetTasks(limit, offset int, agentID, status, action string) ([]models.Task, int, error) {
	if limit <= 0 {
		limit = 50
	}

	where := []string{}
	args := []interface{}{}
	argIdx := 1

	if agentID != "" {
		where = append(where, fmt.Sprintf("t.agent_id = $%d", argIdx))
		args = append(args, agentID)
		argIdx++
	}
	if status != "" {
		where = append(where, fmt.Sprintf("t.status = $%d", argIdx))
		args = append(args, status)
		argIdx++
	}
	if action != "" {
		where = append(where, fmt.Sprintf("t.action = $%d", argIdx))
		args = append(args, action)
		argIdx++
	}

	whereClause := ""
	if len(where) > 0 {
		whereClause = "WHERE " + strings.Join(where, " AND ")
	}

	var total int
	countQuery := "SELECT COUNT(*) FROM tasks t " + whereClause
	if err := d.db.QueryRow(countQuery, args...).Scan(&total); err != nil {
		return nil, 0, err
	}

	query := fmt.Sprintf("SELECT %s %s %s ORDER BY t.created_at DESC LIMIT $%d OFFSET $%d",
		taskSelectCols, taskFromJoin, whereClause, argIdx, argIdx+1)
	args = append(args, limit, offset)

	rows, err := d.db.Query(query, args...)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	var tasks []models.Task
	for rows.Next() {
		t, err := scanTask(rows.Scan)
		if err != nil {
			return nil, 0, err
		}
		tasks = append(tasks, *t)
	}
	if tasks == nil {
		tasks = []models.Task{}
	}
	return tasks, total, rows.Err()
}

func (d *Database) UpdateTaskStatus(id int, status string, result interface{}) error {
	var resultJSON *string
	if result != nil {
		b, err := json.Marshal(result)
		if err == nil {
			s := string(b)
			resultJSON = &s
		}
	}

	now := time.Now().UTC()

	switch status {
	case "running":
		_, err := d.db.Exec(
			"UPDATE tasks SET status = $1, started_at = $2 WHERE id = $3",
			status, now, id,
		)
		return err
	case "completed", "failed":
		_, err := d.db.Exec(
			"UPDATE tasks SET status = $1, finished_at = $2, result = $3 WHERE id = $4",
			status, now, resultJSON, id,
		)
		return err
	default:
		_, err := d.db.Exec("UPDATE tasks SET status = $1 WHERE id = $2", status, id)
		return err
	}
}

// CompleteRecurringTask handles post-execution for recurring tasks.
func (d *Database) CompleteRecurringTask(id int, scheduleType, scheduleTime string, weekday, monthday *int, success bool, result interface{}) error {
	var resultJSON *string
	if result != nil {
		b, err := json.Marshal(result)
		if err == nil {
			s := string(b)
			resultJSON = &s
		}
	}

	now := time.Now()

	if scheduleType == "once" {
		status := "completed"
		if !success {
			status = "failed"
		}
		_, err := d.db.Exec(
			`UPDATE tasks SET status = $1, finished_at = $2, result = $3, active = FALSE,
			 last_run = $2, run_count = run_count + 1 WHERE id = $4`,
			status, now, resultJSON, id,
		)
		return err
	}

	// Recurring: reset to scheduled, compute next_run
	nextRun := CalculateNextRun(scheduleType, scheduleTime, weekday, monthday, now)
	_, err := d.db.Exec(
		`UPDATE tasks SET status = 'scheduled', finished_at = $1, result = $2,
		 last_run = $1, next_run = $3, run_count = run_count + 1,
		 started_at = NULL WHERE id = $4`,
		now, resultJSON, nextRun, id,
	)
	return err
}

func (d *Database) SetTaskWebhookResult(id int, sent bool, response string) error {
	if len(response) > 500 {
		response = response[:500]
	}
	_, err := d.db.Exec(
		"UPDATE tasks SET webhook_sent = $1, webhook_response = $2 WHERE id = $3",
		sent, response, id,
	)
	return err
}

func (d *Database) GetDueTasks() ([]models.Task, error) {
	query := fmt.Sprintf(`SELECT %s %s
		WHERE t.active = TRUE AND t.next_run IS NOT NULL AND t.next_run <= NOW() AND t.status != 'running'
		ORDER BY t.next_run ASC`, taskSelectCols, taskFromJoin)

	rows, err := d.db.Query(query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var tasks []models.Task
	for rows.Next() {
		t, err := scanTask(rows.Scan)
		if err != nil {
			return nil, err
		}
		tasks = append(tasks, *t)
	}
	return tasks, rows.Err()
}

func (d *Database) ToggleTask(id int) (*models.Task, error) {
	_, err := d.db.Exec("UPDATE tasks SET active = NOT active WHERE id = $1", id)
	if err != nil {
		return nil, err
	}
	return d.GetTask(id)
}

func (d *Database) CancelTask(id int) error {
	res, err := d.db.Exec(
		"UPDATE tasks SET status = 'cancelled' WHERE id = $1 AND status = 'scheduled'",
		id,
	)
	if err != nil {
		return err
	}
	rows, _ := res.RowsAffected()
	if rows == 0 {
		return fmt.Errorf("Task nicht gefunden oder nicht mehr im Status 'scheduled'")
	}
	return nil
}

// UpdateTaskStatusDirect sets only the status field (for post-completion overrides).
func (d *Database) UpdateTaskStatusDirect(id int, status string) error {
	_, err := d.db.Exec("UPDATE tasks SET status = $1 WHERE id = $2", status, id)
	return err
}

func (d *Database) UpdateTask(id int, name, scheduleType, scheduleTime string, weekday, monthday *int,
	reboot, healthCheck bool, healthCheckTimeout int, webhookURL string, active bool) (*models.Task, error) {

	now := time.Now()
	nextRun := CalculateNextRun(scheduleType, scheduleTime, weekday, monthday, now)

	_, err := d.db.Exec(`
		UPDATE tasks SET
			name = $1, schedule_type = $2, schedule_time = $3,
			schedule_weekday = $4, schedule_monthday = $5,
			reboot = $6, health_check = $7, health_check_timeout = $8,
			webhook_url = $9, active = $10, next_run = $11
		WHERE id = $12
	`, name, scheduleType, scheduleTime, weekday, monthday,
		reboot, healthCheck, healthCheckTimeout, webhookURL, active, nextRun, id)
	if err != nil {
		return nil, fmt.Errorf("Task aktualisieren: %w", err)
	}
	return d.GetTask(id)
}

func (d *Database) DeleteTask(id int) error {
	res, err := d.db.Exec("DELETE FROM tasks WHERE id = $1", id)
	if err != nil {
		return err
	}
	rows, _ := res.RowsAffected()
	if rows == 0 {
		return fmt.Errorf("Task nicht gefunden")
	}
	return nil
}