package httpapi

import (
	"fmt"
	"strconv"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/syncova/syncova/packages/jobs"
	"github.com/syncova/syncova/packages/scheduler"
)

// buildJobFromRequest wandelt einen Anfragerumpf in einen Auftrag.
//
// Die Prüfung der Werte bleibt der Fachschicht überlassen; hier wird nur
// übersetzt. Zwei Prüfstellen mit eigenen Regeln liefen unweigerlich
// auseinander.
func buildJobFromRequest(jobPayload jobRequest, creatorID uuid.UUID) (*jobs.Job, *APIError) {
	parsedSchedule, scheduleError := buildScheduleFromRequest(jobPayload.Schedule)
	if scheduleError != nil {
		return nil, scheduleError
	}

	jobPriority := scheduler.Priority(jobPayload.Priority)
	if jobPayload.Priority == "" {
		jobPriority = scheduler.PriorityNormal
	}

	maximumConcurrency := jobPayload.MaximumConcurrency
	if maximumConcurrency < 1 {
		maximumConcurrency = 1
	}

	jobSources := make([]jobs.JobSource, 0, len(jobPayload.Sources))
	for _, requestedSource := range jobPayload.Sources {
		jobSources = append(jobSources, jobs.JobSource{
			SourceType:      jobs.SourceType(requestedSource.Type),
			SourceID:        requestedSource.ID,
			SourceName:      requestedSource.Name,
			AgentID:         requestedSource.AgentID,
			IncludePatterns: requestedSource.IncludePatterns,
			ExcludePatterns: requestedSource.ExcludePatterns,
		})
	}

	builtJob := &jobs.Job{
		Name:                         strings.TrimSpace(jobPayload.Name),
		Description:                  strings.TrimSpace(jobPayload.Description),
		Status:                       jobs.JobStatusActive,
		Priority:                     jobPriority,
		Schedule:                     parsedSchedule,
		Sources:                      jobSources,
		RepositoryID:                 jobPayload.RepositoryID,
		RetentionPolicyID:            jobPayload.RetentionPolicyID,
		DependsOnJobIDs:              jobPayload.DependsOnJobIDs,
		RecoveryPointObjective:       time.Duration(jobPayload.RecoveryPointSeconds) * time.Second,
		RecoveryTimeObjective:        time.Duration(jobPayload.RecoveryTimeSeconds) * time.Second,
		BandwidthLimitBytesPerSecond: jobPayload.BandwidthLimitBytesPerSecond,
		BackupMode:                   jobs.BackupMode(jobPayload.BackupMode),
		FullBackupWeekday:            weekdayFromPayload(jobPayload.FullBackupWeekday),
		MaximumConcurrency:           maximumConcurrency,
		RetryPolicy:                  scheduler.DefaultRetryPolicy(),
		CreatedBy:                    &creatorID,
	}

	// Die fachliche Prüfung läuft hier, damit ein fehlerhafter Auftrag mit 422
	// beantwortet wird statt mit einem Datenbankfehler als 500.
	if validationError := builtJob.Validate(); validationError != nil {
		return nil, NewValidationError(validationError.Error())
	}

	return builtJob, nil
}

// buildScheduleFromRequest wandelt eine Zeitplanangabe.
func buildScheduleFromRequest(scheduleData scheduleRequest) (scheduler.Schedule, *APIError) {
	builtSchedule := scheduler.Schedule{
		ScheduleType:   scheduler.ScheduleType(scheduleData.Type),
		CronExpression: scheduleData.CronExpression,
		TimeZone:       scheduleData.TimeZone,
		MonthDays:      scheduleData.MonthDays,
		Interval:       time.Duration(scheduleData.IntervalSeconds) * time.Second,
	}

	if scheduleData.Time != "" {
		parsedHour, parsedMinute, timeError := parseClockTime(scheduleData.Time)
		if timeError != nil {
			return scheduler.Schedule{}, NewValidationError(timeError.Error())
		}

		builtSchedule.Hour = parsedHour
		builtSchedule.Minute = parsedMinute
	}

	for _, weekdayNumber := range scheduleData.Weekdays {
		if weekdayNumber < 0 || weekdayNumber > 6 {
			return scheduler.Schedule{}, NewValidationError(
				fmt.Sprintf("Der Wochentag %d ist unbekannt; zulässig sind 0 (Sonntag) bis 6 (Samstag).", weekdayNumber))
		}

		builtSchedule.Weekdays = append(builtSchedule.Weekdays, time.Weekday(weekdayNumber))
	}

	return builtSchedule, nil
}

// parseClockTime liest eine Uhrzeit im Format "HH:MM".
func parseClockTime(clockText string) (int, int, error) {
	hourText, minuteText, hasSeparator := strings.Cut(strings.TrimSpace(clockText), ":")
	if !hasSeparator {
		return 0, 0, fmt.Errorf("Die Uhrzeit %q muss im Format HH:MM angegeben werden.", clockText)
	}

	parsedHour, hourError := strconv.Atoi(hourText)
	if hourError != nil || parsedHour < 0 || parsedHour > 23 {
		return 0, 0, fmt.Errorf("Die Stunde in %q liegt nicht zwischen 00 und 23.", clockText)
	}

	parsedMinute, minuteError := strconv.Atoi(minuteText)
	if minuteError != nil || parsedMinute < 0 || parsedMinute > 59 {
		return 0, 0, fmt.Errorf("Die Minute in %q liegt nicht zwischen 00 und 59.", clockText)
	}

	return parsedHour, parsedMinute, nil
}

// buildJobResponse wandelt einen Auftrag in seine Darstellung nach außen.
func buildJobResponse(sourceJob *jobs.Job) jobResponse {
	sourceResponses := make([]sourceRequest, 0, len(sourceJob.Sources))
	for _, jobSource := range sourceJob.Sources {
		sourceResponses = append(sourceResponses, sourceRequest{
			Type:            string(jobSource.SourceType),
			ID:              jobSource.SourceID,
			Name:            jobSource.SourceName,
			AgentID:         jobSource.AgentID,
			IncludePatterns: jobSource.IncludePatterns,
			ExcludePatterns: jobSource.ExcludePatterns,
		})
	}

	return jobResponse{
		ID:                           sourceJob.ID,
		Name:                         sourceJob.Name,
		Description:                  sourceJob.Description,
		Status:                       string(sourceJob.Status),
		Priority:                     string(sourceJob.Priority),
		Schedule:                     buildScheduleResponse(sourceJob.Schedule),
		ScheduleDescription:          sourceJob.Schedule.Describe(),
		Sources:                      sourceResponses,
		RepositoryID:                 sourceJob.RepositoryID,
		RetentionPolicyID:            sourceJob.RetentionPolicyID,
		DependsOnJobIDs:              sourceJob.DependsOnJobIDs,
		RecoveryPointSeconds:         int64(sourceJob.RecoveryPointObjective.Seconds()),
		RecoveryTimeSeconds:          int64(sourceJob.RecoveryTimeObjective.Seconds()),
		BandwidthLimitBytesPerSecond: sourceJob.BandwidthLimitBytesPerSecond,
		BackupMode:                   string(sourceJob.BackupMode),
		FullBackupWeekday:            weekdayToPayload(sourceJob.FullBackupWeekday),
		MaximumConcurrency:           sourceJob.MaximumConcurrency,
		NextRunAt:                    sourceJob.NextRunAt,
		LastRunAt:                    sourceJob.LastRunAt,
		LastOutcome:                  string(sourceJob.LastOutcome),
		PausedAt:                     sourceJob.PausedAt,
		CreatedAt:                    sourceJob.CreatedAt,
		UpdatedAt:                    sourceJob.UpdatedAt,
	}
}

// buildScheduleResponse wandelt einen Zeitplan in seine Darstellung.
func buildScheduleResponse(sourceSchedule scheduler.Schedule) scheduleRequest {
	scheduleData := scheduleRequest{
		Type:           string(sourceSchedule.ScheduleType),
		CronExpression: sourceSchedule.CronExpression,
		TimeZone:       sourceSchedule.TimeZone,
		MonthDays:      sourceSchedule.MonthDays,
	}

	if sourceSchedule.Interval > 0 {
		scheduleData.IntervalSeconds = int64(sourceSchedule.Interval.Seconds())
	}

	// Die Uhrzeit erscheint nur bei den Zeitplänen, die eine haben. Bei einem
	// Intervallplan wäre "00:00" eine Angabe, die es nicht gibt.
	switch sourceSchedule.ScheduleType {
	case scheduler.ScheduleTypeDaily, scheduler.ScheduleTypeWeekly, scheduler.ScheduleTypeMonthly:
		scheduleData.Time = fmt.Sprintf("%02d:%02d", sourceSchedule.Hour, sourceSchedule.Minute)
	case scheduler.ScheduleTypeHourly:
		scheduleData.Time = fmt.Sprintf(":%02d", sourceSchedule.Minute)
	}

	for _, scheduleWeekday := range sourceSchedule.Weekdays {
		scheduleData.Weekdays = append(scheduleData.Weekdays, int(scheduleWeekday))
	}

	return scheduleData
}

// weekdayFromPayload uebersetzt einen Wochentag aus der Anfrage.
//
// Ein Wert ausserhalb von 0..6 wird verworfen statt gekappt: Ein
// stillschweigend auf Sonntag gesetzter Montag waere ein Fehler, den niemand
// bemerkt — die Vollsicherung liefe dann am falschen Tag.
func weekdayFromPayload(requestedWeekday *int) *time.Weekday {
	if requestedWeekday == nil {
		return nil
	}

	if *requestedWeekday < 0 || *requestedWeekday > 6 {
		return nil
	}

	convertedWeekday := time.Weekday(*requestedWeekday)

	return &convertedWeekday
}

// weekdayToPayload uebersetzt einen Wochentag fuer die Antwort.
func weekdayToPayload(storedWeekday *time.Weekday) *int {
	if storedWeekday == nil {
		return nil
	}

	convertedValue := int(*storedWeekday)

	return &convertedValue
}