paliad/internal/services/appointment_service.go

package services

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/jmoiron/sqlx"

	"mgit.msbls.de/m/paliad/internal/models"
)

// AppointmentService reads and writes paliad.appointments.
//
// Visibility:
//   - project_id IS NULL → personal Appointment, visible/editable only to created_by
//   - project_id IS NOT NULL → follows ProjectService.GetByID team gate
//
// Audit: Project-attached mutations append project_events rows. Personal
// Appointments never touch project_events.
//
// CalDAV: optional hook (AppointmentCalDAVPusher) is called best-effort after
// each mutation.
type AppointmentService struct {
	db       *sqlx.DB
	projects *ProjectService

	caldav AppointmentCalDAVPusher
}

// AppointmentCalDAVPusher is the contract the CalDAV service implements so the
// AppointmentService can push individual appointment changes without importing the
// caldav package directly.
type AppointmentCalDAVPusher interface {
	OnAppointmentCreated(ctx context.Context, userID uuid.UUID, t *models.Appointment)
	OnAppointmentUpdated(ctx context.Context, userID uuid.UUID, t *models.Appointment)
	OnAppointmentDeleted(ctx context.Context, userID uuid.UUID, t *models.Appointment)
}

func NewAppointmentService(db *sqlx.DB, projects *ProjectService) *AppointmentService {
	return &AppointmentService{db: db, projects: projects}
}

// SetCalDAVPusher wires an optional CalDAV push hook.
func (s *AppointmentService) SetCalDAVPusher(p AppointmentCalDAVPusher) {
	s.caldav = p
}

const appointmentColumns = `id, project_id, title, description, start_at, end_at,
	location, appointment_type, caldav_uid, caldav_etag, created_by,
	created_at, updated_at`

// CreateAppointmentInput is the payload for POST /api/appointments.
type CreateAppointmentInput struct {
	ProjectID   *uuid.UUID `json:"project_id,omitempty"`
	Title       string     `json:"title"`
	Description *string    `json:"description,omitempty"`
	StartAt     time.Time  `json:"start_at"`
	EndAt       *time.Time `json:"end_at,omitempty"`
	Location    *string    `json:"location,omitempty"`
	AppointmentType  *string    `json:"appointment_type,omitempty"`
}

// UpdateAppointmentInput is the partial-update payload for PATCH /api/appointments/{id}.
type UpdateAppointmentInput struct {
	Title       *string    `json:"title,omitempty"`
	Description *string    `json:"description,omitempty"`
	StartAt     *time.Time `json:"start_at,omitempty"`
	EndAt       *time.Time `json:"end_at,omitempty"`
	Location    *string    `json:"location,omitempty"`
	AppointmentType  *string    `json:"appointment_type,omitempty"`
}

// AppointmentListFilter narrows ListVisibleForUser results.
type AppointmentListFilter struct {
	ProjectID *uuid.UUID
	From      *time.Time
	To        *time.Time
	Type      *string
}

// ListVisibleForUser returns all Appointments the user can see (personal +
// Project-attached they have visibility for), ordered by start_at ascending.
func (s *AppointmentService) ListVisibleForUser(ctx context.Context, userID uuid.UUID, filter AppointmentListFilter) ([]models.AppointmentWithProject, error) {
	user, err := s.users().GetByID(ctx, userID)
	if err != nil {
		return nil, err
	}
	if user == nil {
		return []models.AppointmentWithProject{}, nil
	}

	visibility := `(
		(t.project_id IS NULL AND t.created_by = :user_id)
		OR (t.project_id IS NOT NULL AND ` + visibilityPredicate("p") + `)
	)`
	conds := []string{visibility}
	args := map[string]any{
		"user_id": userID,
	}

	if filter.ProjectID != nil {
		conds = append(conds, projectDescendantPredicate("p"))
		args["project_id"] = *filter.ProjectID
	}
	if filter.From != nil {
		conds = append(conds, `t.start_at >= :from`)
		args["from"] = *filter.From
	}
	if filter.To != nil {
		conds = append(conds, `t.start_at <= :to`)
		args["to"] = *filter.To
	}
	if filter.Type != nil {
		if !isValidAppointmentType(*filter.Type) {
			return nil, fmt.Errorf("%w: invalid appointment_type %q", ErrInvalidInput, *filter.Type)
		}
		conds = append(conds, `t.appointment_type = :type`)
		args["type"] = *filter.Type
	}

	query := `
		SELECT t.id, t.project_id, t.title, t.description, t.start_at, t.end_at,
		       t.location, t.appointment_type, t.caldav_uid, t.caldav_etag,
		       t.created_by, t.created_at, t.updated_at,
		       p.reference AS project_reference,
		       p.title     AS project_title,
		       p.type      AS project_type
		  FROM paliad.appointments t
		  LEFT JOIN paliad.projects p ON p.id = t.project_id
		 WHERE ` + strings.Join(conds, " AND ") + `
		 ORDER BY t.start_at ASC, t.created_at DESC`

	stmt, err := s.db.PrepareNamedContext(ctx, query)
	if err != nil {
		return nil, fmt.Errorf("prepare list appointments: %w", err)
	}
	defer stmt.Close()

	rows := []models.AppointmentWithProject{}
	if err := stmt.SelectContext(ctx, &rows, args); err != nil {
		return nil, fmt.Errorf("list appointments: %w", err)
	}
	return rows, nil
}

// ListForProject returns Appointments for a specific Project, visibility-checked.
func (s *AppointmentService) ListForProject(ctx context.Context, userID, projectID uuid.UUID) ([]models.Appointment, error) {
	if _, err := s.projects.GetByID(ctx, userID, projectID); err != nil {
		return nil, err
	}
	rows := []models.Appointment{}
	if err := s.db.SelectContext(ctx, &rows,
		`SELECT `+appointmentColumns+`
		   FROM paliad.appointments
		  WHERE project_id = $1
		  ORDER BY start_at ASC, created_at DESC`, projectID); err != nil {
		return nil, fmt.Errorf("list appointments for project: %w", err)
	}
	return rows, nil
}

// CanSee reports whether the user has visibility on the Appointment. Returns
// (false, nil) for invisible or missing — handlers must not distinguish.
// Cheaper than GetByID when only the visibility bit is needed (no projection
// of the full row); used by sibling services (NoteService, etc.) to gate on
// the parent without paying for a full SELECT plus a follow-up project read.
func (s *AppointmentService) CanSee(ctx context.Context, userID, appointmentID uuid.UUID) (bool, error) {
	var visible bool
	query := `SELECT EXISTS (
	    SELECT 1
	      FROM paliad.appointments t
	      LEFT JOIN paliad.projects p ON p.id = t.project_id
	     WHERE t.id = $1 AND (
	         (t.project_id IS NULL AND t.created_by = $2)
	         OR (t.project_id IS NOT NULL AND ` + visibilityPredicatePositional("p", 2) + `)
	     )
	)`
	if err := s.db.GetContext(ctx, &visible, query, appointmentID, userID); err != nil {
		return false, fmt.Errorf("check appointment visibility: %w", err)
	}
	return visible, nil
}

// GetByID returns a single Appointment if the user has visibility.
func (s *AppointmentService) GetByID(ctx context.Context, userID, appointmentID uuid.UUID) (*models.Appointment, error) {
	var t models.Appointment
	err := s.db.GetContext(ctx, &t,
		`SELECT `+appointmentColumns+` FROM paliad.appointments WHERE id = $1`, appointmentID)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotVisible
	}
	if err != nil {
		return nil, fmt.Errorf("fetch appointment: %w", err)
	}

	if !s.canSee(ctx, userID, &t) {
		return nil, ErrNotVisible
	}
	return &t, nil
}

// requireMutationRole enforces the partner/admin gate on Project-linked
// Appointment mutations. The Appointment's own creator is also allowed.
func (s *AppointmentService) requireMutationRole(ctx context.Context, userID uuid.UUID, t *models.Appointment) error {
	if t.CreatedBy != nil && *t.CreatedBy == userID {
		return nil
	}
	user, err := s.users().GetByID(ctx, userID)
	if err != nil {
		return err
	}
	if user == nil {
		return ErrNotVisible
	}
	if user.GlobalRole != "global_admin" {
		return fmt.Errorf("%w: only partners/admins can modify Appointments on a Project", ErrForbidden)
	}
	return nil
}

// canSee mirrors the SELECT visibility predicate for one in-memory Appointment.
func (s *AppointmentService) canSee(ctx context.Context, userID uuid.UUID, t *models.Appointment) bool {
	if t.ProjectID == nil {
		return t.CreatedBy != nil && *t.CreatedBy == userID
	}
	_, err := s.projects.GetByID(ctx, userID, *t.ProjectID)
	return err == nil
}

// Create inserts a Appointment. If project_id is set, ProjectService visibility
// is enforced and the Project's audit trail records the new appointment.
func (s *AppointmentService) Create(ctx context.Context, userID uuid.UUID, input CreateAppointmentInput) (*models.Appointment, error) {
	title := strings.TrimSpace(input.Title)
	if title == "" {
		return nil, fmt.Errorf("%w: title is required", ErrInvalidInput)
	}
	if input.StartAt.IsZero() {
		return nil, fmt.Errorf("%w: start_at is required", ErrInvalidInput)
	}
	if input.EndAt != nil && input.EndAt.Before(input.StartAt) {
		return nil, fmt.Errorf("%w: end_at must be after start_at", ErrInvalidInput)
	}
	if input.AppointmentType != nil && *input.AppointmentType != "" && !isValidAppointmentType(*input.AppointmentType) {
		return nil, fmt.Errorf("%w: invalid appointment_type %q", ErrInvalidInput, *input.AppointmentType)
	}

	if input.ProjectID != nil {
		if _, err := s.projects.GetByID(ctx, userID, *input.ProjectID); err != nil {
			return nil, err
		}
	}

	id := uuid.New()
	now := time.Now().UTC()

	tx, err := s.db.BeginTxx(ctx, nil)
	if err != nil {
		return nil, fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback()

	if _, err := tx.ExecContext(ctx,
		`INSERT INTO paliad.appointments
		   (id, project_id, title, description, start_at, end_at, location,
		    appointment_type, created_by, created_at, updated_at)
		 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $10)`,
		id, input.ProjectID, title, input.Description, input.StartAt.UTC(),
		nullableUTC(input.EndAt), input.Location, input.AppointmentType, userID, now,
	); err != nil {
		return nil, fmt.Errorf("insert appointment: %w", err)
	}

	if input.ProjectID != nil {
		// Description carries value-only payload (the appointment title); frontend
		// renders via the localized event.description.appointment_* template. Same
		// pattern for updated/deleted below. Metadata carries the appointment id
		// so the Verlauf entry deep-links to /appointments/{id} (t-paliad-102).
		desc := title
		descPtr := &desc
		if err := insertProjectEventWithMeta(ctx, tx, *input.ProjectID, userID, "appointment_created", "Appointment created", descPtr,
			map[string]any{"appointment_id": id}); err != nil {
			return nil, err
		}
	}
	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("commit insert appointment: %w", err)
	}

	t, err := s.GetByID(ctx, userID, id)
	if err != nil {
		return nil, err
	}
	if s.caldav != nil {
		s.caldav.OnAppointmentCreated(ctx, userID, t)
	}
	return t, nil
}

// Update applies a partial update.
func (s *AppointmentService) Update(ctx context.Context, userID, appointmentID uuid.UUID, input UpdateAppointmentInput) (*models.Appointment, error) {
	current, err := s.GetByID(ctx, userID, appointmentID)
	if err != nil {
		return nil, err
	}
	if current.ProjectID == nil {
		if current.CreatedBy == nil || *current.CreatedBy != userID {
			return nil, fmt.Errorf("%w: only the creator can edit a personal Appointment", ErrForbidden)
		}
	} else if err := s.requireMutationRole(ctx, userID, current); err != nil {
		return nil, err
	}

	sets := []string{}
	args := []any{}
	next := 1
	appendSet := func(col string, val any) {
		sets = append(sets, fmt.Sprintf("%s = $%d", col, next))
		args = append(args, val)
		next++
	}

	if input.Title != nil {
		title := strings.TrimSpace(*input.Title)
		if title == "" {
			return nil, fmt.Errorf("%w: title cannot be empty", ErrInvalidInput)
		}
		appendSet("title", title)
	}
	if input.Description != nil {
		appendSet("description", *input.Description)
	}
	if input.StartAt != nil {
		appendSet("start_at", input.StartAt.UTC())
	}
	if input.EndAt != nil {
		appendSet("end_at", input.EndAt.UTC())
	}
	if input.Location != nil {
		appendSet("location", *input.Location)
	}
	if input.AppointmentType != nil {
		if *input.AppointmentType != "" && !isValidAppointmentType(*input.AppointmentType) {
			return nil, fmt.Errorf("%w: invalid appointment_type %q", ErrInvalidInput, *input.AppointmentType)
		}
		appendSet("appointment_type", *input.AppointmentType)
	}
	if len(sets) == 0 {
		return current, nil
	}
	appendSet("updated_at", time.Now().UTC())
	args = append(args, appointmentID)

	query := fmt.Sprintf("UPDATE paliad.appointments SET %s WHERE id = $%d",
		strings.Join(sets, ", "), next)

	tx, err := s.db.BeginTxx(ctx, nil)
	if err != nil {
		return nil, fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback()

	if _, err := tx.ExecContext(ctx, query, args...); err != nil {
		return nil, fmt.Errorf("update appointment: %w", err)
	}

	if current.ProjectID != nil {
		desc := current.Title
		descPtr := &desc
		if err := insertProjectEventWithMeta(ctx, tx, *current.ProjectID, userID, "appointment_updated", "Appointment updated", descPtr,
			map[string]any{"appointment_id": appointmentID}); err != nil {
			return nil, err
		}
	}
	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("commit update appointment: %w", err)
	}
	t, err := s.GetByID(ctx, userID, appointmentID)
	if err != nil {
		return nil, err
	}
	if s.caldav != nil {
		s.caldav.OnAppointmentUpdated(ctx, userID, t)
	}
	return t, nil
}

// Delete removes an Appointment.
func (s *AppointmentService) Delete(ctx context.Context, userID, appointmentID uuid.UUID) error {
	current, err := s.GetByID(ctx, userID, appointmentID)
	if err != nil {
		return err
	}
	if current.ProjectID == nil {
		if current.CreatedBy == nil || *current.CreatedBy != userID {
			return fmt.Errorf("%w: only the creator can delete a personal Appointment", ErrForbidden)
		}
	} else if err := s.requireMutationRole(ctx, userID, current); err != nil {
		return err
	}

	tx, err := s.db.BeginTxx(ctx, nil)
	if err != nil {
		return fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback()

	if _, err := tx.ExecContext(ctx,
		`DELETE FROM paliad.appointments WHERE id = $1`, appointmentID); err != nil {
		return fmt.Errorf("delete appointment: %w", err)
	}
	if current.ProjectID != nil {
		desc := current.Title
		descPtr := &desc
		if err := insertProjectEvent(ctx, tx, *current.ProjectID, userID, "appointment_deleted", "Appointment deleted", descPtr); err != nil {
			return err
		}
	}
	if err := tx.Commit(); err != nil {
		return fmt.Errorf("commit delete appointment: %w", err)
	}
	if s.caldav != nil {
		s.caldav.OnAppointmentDeleted(ctx, userID, current)
	}
	return nil
}

// AppointmentSummaryCounts buckets visible Appointments into today / this_week / later.
type AppointmentSummaryCounts struct {
	Today    int `json:"today"     db:"today"`
	ThisWeek int `json:"this_week" db:"this_week"`
	Later    int `json:"later"     db:"later"`
	Total    int `json:"total"     db:"total"`
}

// SummaryCounts aggregates Appointments by start-date bucket for the user's visible projects.
func (s *AppointmentService) SummaryCounts(ctx context.Context, userID uuid.UUID) (*AppointmentSummaryCounts, error) {
	user, err := s.users().GetByID(ctx, userID)
	if err != nil {
		return nil, err
	}
	if user == nil {
		return &AppointmentSummaryCounts{}, nil
	}
	now := time.Now().UTC()
	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, time.UTC)
	tomorrow := today.AddDate(0, 0, 1)
	endOfWeek := today.AddDate(0, 0, 7)

	query := `
		SELECT
		  COUNT(*) FILTER (WHERE t.start_at >= :today    AND t.start_at < :tomorrow) AS today,
		  COUNT(*) FILTER (WHERE t.start_at >= :tomorrow AND t.start_at < :endweek)  AS this_week,
		  COUNT(*) FILTER (WHERE t.start_at >= :endweek)                              AS later,
		  COUNT(*) FILTER (WHERE t.start_at >= :today)                                AS total
		  FROM paliad.appointments t
		  LEFT JOIN paliad.projects p ON p.id = t.project_id
		 WHERE
		   (t.project_id IS NULL AND t.created_by = :user_id)
		   OR (t.project_id IS NOT NULL AND ` + visibilityPredicate("p") + `)`

	stmt, err := s.db.PrepareNamedContext(ctx, query)
	if err != nil {
		return nil, fmt.Errorf("prepare appointment summary: %w", err)
	}
	defer stmt.Close()

	var c AppointmentSummaryCounts
	if err := stmt.GetContext(ctx, &c, map[string]any{
		"today":    today,
		"tomorrow": tomorrow,
		"endweek":  endOfWeek,
		"user_id":  userID,
	}); err != nil {
		return nil, fmt.Errorf("appointment summary: %w", err)
	}
	return &c, nil
}

// SetCalDAVMeta is called by the CalDAV service after a successful push.
func (s *AppointmentService) SetCalDAVMeta(ctx context.Context, appointmentID uuid.UUID, uid, etag string) error {
	_, err := s.db.ExecContext(ctx,
		`UPDATE paliad.appointments
		    SET caldav_uid = $1, caldav_etag = $2, updated_at = NOW()
		  WHERE id = $3`, uid, etag, appointmentID)
	if err != nil {
		return fmt.Errorf("update appointment caldav meta: %w", err)
	}
	return nil
}

// AllForUser returns every Appointment (personal + visible Project-attached) the
// user owns. Used by the CalDAV push loop.
func (s *AppointmentService) AllForUser(ctx context.Context, userID uuid.UUID) ([]models.Appointment, error) {
	user, err := s.users().GetByID(ctx, userID)
	if err != nil {
		return nil, err
	}
	if user == nil {
		return nil, nil
	}
	rows := []models.Appointment{}
	query := `
		SELECT ` + appointmentColumns + `
		  FROM paliad.appointments t
		  LEFT JOIN paliad.projects p ON p.id = t.project_id
		 WHERE
		   (t.project_id IS NULL AND t.created_by = $1)
		   OR (t.project_id IS NOT NULL AND ` + visibilityPredicatePositional("p", 1) + `)`
	if err := s.db.SelectContext(ctx, &rows, query, userID); err != nil {
		return nil, fmt.Errorf("all appointments for user: %w", err)
	}
	return rows, nil
}

// FindByCalDAVUID resolves a Appointment from its external UID.
func (s *AppointmentService) FindByCalDAVUID(ctx context.Context, uid string) (*models.Appointment, error) {
	var t models.Appointment
	err := s.db.GetContext(ctx, &t,
		`SELECT `+appointmentColumns+` FROM paliad.appointments WHERE caldav_uid = $1`, uid)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, ErrNotVisible
	}
	if err != nil {
		return nil, fmt.Errorf("find appointment by caldav uid: %w", err)
	}
	return &t, nil
}

// ApplyRemoteUpdate writes pulled CalDAV changes into the local row.
func (s *AppointmentService) ApplyRemoteUpdate(ctx context.Context, appointmentID uuid.UUID, title, description, location *string, startAt, endAt *time.Time, etag string) (bool, error) {
	sets := []string{"caldav_etag = $1", "updated_at = NOW()"}
	args := []any{etag}
	next := 2
	changed := false
	if title != nil {
		sets = append(sets, fmt.Sprintf("title = $%d", next))
		args = append(args, *title)
		next++
		changed = true
	}
	if description != nil {
		sets = append(sets, fmt.Sprintf("description = $%d", next))
		args = append(args, *description)
		next++
		changed = true
	}
	if location != nil {
		sets = append(sets, fmt.Sprintf("location = $%d", next))
		args = append(args, *location)
		next++
		changed = true
	}
	if startAt != nil {
		sets = append(sets, fmt.Sprintf("start_at = $%d", next))
		args = append(args, startAt.UTC())
		next++
		changed = true
	}
	if endAt != nil {
		sets = append(sets, fmt.Sprintf("end_at = $%d", next))
		args = append(args, endAt.UTC())
		next++
		changed = true
	}
	args = append(args, appointmentID)
	query := fmt.Sprintf("UPDATE paliad.appointments SET %s WHERE id = $%d",
		strings.Join(sets, ", "), next)
	if _, err := s.db.ExecContext(ctx, query, args...); err != nil {
		return false, fmt.Errorf("apply remote appointment update: %w", err)
	}
	return changed, nil
}

// DeleteByCalDAVUID removes an Appointment pulled-deleted from the remote calendar.
func (s *AppointmentService) DeleteByCalDAVUID(ctx context.Context, uid string) error {
	_, err := s.db.ExecContext(ctx,
		`DELETE FROM paliad.appointments WHERE caldav_uid = $1`, uid)
	if err != nil {
		return fmt.Errorf("delete appointment by caldav uid: %w", err)
	}
	return nil
}

// LogConflict appends a conflict event to the parent Project's audit trail.
// No-op for personal Appointments.
func (s *AppointmentService) LogConflict(ctx context.Context, appointmentID uuid.UUID, msg string) error {
	var row struct {
		ProjectID *uuid.UUID `db:"project_id"`
		CreatedBy *uuid.UUID `db:"created_by"`
	}
	err := s.db.GetContext(ctx, &row,
		`SELECT project_id, created_by FROM paliad.appointments WHERE id = $1`, appointmentID)
	if err != nil || row.ProjectID == nil {
		return nil //nolint:nilerr
	}
	now := time.Now().UTC()
	desc := msg
	_, err = s.db.ExecContext(ctx,
		`INSERT INTO paliad.project_events
		   (id, project_id, event_type, title, description, event_date,
		    created_by, metadata, created_at, updated_at)
		 VALUES ($1, $2, 'caldav_conflict', 'CalDAV conflict', $3, $4, $5, '{}', $4, $4)`,
		uuid.New(), *row.ProjectID, desc, now, row.CreatedBy)
	if err != nil {
		return fmt.Errorf("insert caldav conflict event: %w", err)
	}
	return nil
}

// users returns the shared user service via the Project handle.
func (s *AppointmentService) users() *UserService {
	return s.projects.Users()
}

func nullableUTC(t *time.Time) any {
	if t == nil {
		return nil
	}
	u := t.UTC()
	return u
}

func isValidAppointmentType(t string) bool {
	switch t {
	case "hearing", "meeting", "consultation", "deadline_hearing":
		return true
	}
	return false
}