paliad/internal/services/deadline_service.go

package services

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

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

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

// DeadlineService reads and writes paliad.deadlines. Visibility inherits from the
// parent Project via ProjectService.GetByID — every read or write goes through
// that gate first.
//
// Audit: every mutation appends a paliad.project_events row via
// insertProjectEvent so the Project verlauf shows what changed.
type DeadlineService struct {
	db       *sqlx.DB
	projects *ProjectService
}

// NewDeadlineService wires the service.
func NewDeadlineService(db *sqlx.DB, projects *ProjectService) *DeadlineService {
	return &DeadlineService{db: db, projects: projects}
}

const fristColumns = `id, project_id, title, description, due_date, original_due_date,
	warning_date, source, rule_id, status, completed_at, caldav_uid, caldav_etag,
	notes, created_by, created_at, updated_at`

// CreateFristInput is the payload for Create / bulk create entries.
type CreateFristInput struct {
	Title           string     `json:"title"`
	Description     *string    `json:"description,omitempty"`
	DueDate         string     `json:"due_date"` // YYYY-MM-DD
	OriginalDueDate *string    `json:"original_due_date,omitempty"`
	RuleID          *uuid.UUID `json:"rule_id,omitempty"`
	Source          string     `json:"source,omitempty"` // default "manual"
	Notes           *string    `json:"notes,omitempty"`
}

// UpdateFristInput is the partial-update payload for PATCH.
type UpdateFristInput struct {
	Title       *string `json:"title,omitempty"`
	Description *string `json:"description,omitempty"`
	DueDate     *string `json:"due_date,omitempty"` // YYYY-MM-DD
	Notes       *string `json:"notes,omitempty"`
	Status      *string `json:"status,omitempty"`
}

// DeadlineStatusFilter is a server-side bucket for ListVisibleForUser.
type DeadlineStatusFilter string

const (
	DeadlineFilterAll       DeadlineStatusFilter = "all"
	DeadlineFilterOverdue   DeadlineStatusFilter = "overdue"
	DeadlineFilterThisWeek  DeadlineStatusFilter = "this_week"
	DeadlineFilterUpcoming  DeadlineStatusFilter = "upcoming"
	DeadlineFilterCompleted DeadlineStatusFilter = "completed"
	DeadlineFilterPending   DeadlineStatusFilter = "pending"
)

// ListFilter narrows ListVisibleForUser results.
type ListFilter struct {
	Status    DeadlineStatusFilter
	ProjectID *uuid.UUID
}

// ListVisibleForUser returns Deadlines on every Project the user can see,
// joined with parent-Project display fields. Sorted by due_date ascending.
func (s *DeadlineService) ListVisibleForUser(ctx context.Context, userID uuid.UUID, filter ListFilter) ([]models.DeadlineWithProject, error) {
	user, err := s.users().GetByID(ctx, userID)
	if err != nil {
		return nil, err
	}
	if user == nil {
		return []models.DeadlineWithProject{}, nil
	}

	conds := []string{visibilityPredicate("p")}
	args := map[string]any{
		"user_id": userID,
		"role":    user.Role,
	}
	if filter.ProjectID != nil {
		conds = append(conds, `f.project_id = :project_id`)
		args["project_id"] = *filter.ProjectID
	}

	now := time.Now().UTC()
	today := now.Truncate(24 * time.Hour)
	endOfWeek := today.AddDate(0, 0, 7)

	switch filter.Status {
	case DeadlineFilterOverdue:
		conds = append(conds, `f.status = 'pending' AND f.due_date < :today`)
		args["today"] = today
	case DeadlineFilterThisWeek:
		conds = append(conds, `f.status = 'pending' AND f.due_date >= :today AND f.due_date < :endweek`)
		args["today"] = today
		args["endweek"] = endOfWeek
	case DeadlineFilterUpcoming:
		conds = append(conds, `f.status = 'pending' AND f.due_date >= :endweek`)
		args["endweek"] = endOfWeek
	case DeadlineFilterCompleted:
		conds = append(conds, `f.status = 'completed'`)
	case DeadlineFilterPending:
		conds = append(conds, `f.status = 'pending'`)
	case DeadlineFilterAll, "":
		// no-op
	default:
		return nil, fmt.Errorf("%w: unknown status filter %q", ErrInvalidInput, filter.Status)
	}

	query := `
		SELECT f.id, f.project_id, f.title, f.description, f.due_date, f.original_due_date,
		       f.warning_date, f.source, f.rule_id, f.status, f.completed_at,
		       f.caldav_uid, f.caldav_etag, f.notes, f.created_by,
		       f.created_at, f.updated_at,
		       p.reference AS project_reference,
		       p.title     AS project_title,
		       p.type      AS project_type,
		       r.code      AS rule_code
		  FROM paliad.deadlines f
		  JOIN paliad.projects p ON p.id = f.project_id
		  LEFT JOIN paliad.deadline_rules r ON r.id = f.rule_id
		 WHERE ` + strings.Join(conds, " AND ") + `
		 ORDER BY f.due_date ASC, f.created_at DESC`

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

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

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

// GetByID returns a single Deadline, with parent Project visibility checked.
func (s *DeadlineService) GetByID(ctx context.Context, userID, fristID uuid.UUID) (*models.Deadline, error) {
	projektID, err := s.parentProjectID(ctx, fristID)
	if err != nil {
		return nil, err
	}
	if _, err := s.projects.GetByID(ctx, userID, projektID); err != nil {
		return nil, err
	}
	var f models.Deadline
	if err := s.db.GetContext(ctx, &f,
		`SELECT `+fristColumns+` FROM paliad.deadlines WHERE id = $1`, fristID); err != nil {
		return nil, fmt.Errorf("fetch deadline: %w", err)
	}
	return &f, nil
}

// Create inserts a single Deadline under a Project.
func (s *DeadlineService) Create(ctx context.Context, userID, projektID uuid.UUID, input CreateFristInput) (*models.Deadline, error) {
	if _, err := s.projects.GetByID(ctx, userID, projektID); err != nil {
		return nil, err
	}
	id, err := s.insert(ctx, userID, projektID, input)
	if err != nil {
		return nil, err
	}
	return s.GetByID(ctx, userID, id)
}

// CreateBulk inserts multiple Deadlines under one Project in a single
// transaction (Fristenrechner "Als Deadline(en) speichern" flow).
func (s *DeadlineService) CreateBulk(ctx context.Context, userID, projektID uuid.UUID, inputs []CreateFristInput) ([]models.Deadline, error) {
	if len(inputs) == 0 {
		return nil, fmt.Errorf("%w: at least one Deadline is required", ErrInvalidInput)
	}
	if _, err := s.projects.GetByID(ctx, userID, projektID); err != nil {
		return nil, err
	}

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

	ids := make([]uuid.UUID, 0, len(inputs))
	for _, in := range inputs {
		id, err := s.insertTx(ctx, tx, userID, projektID, in)
		if err != nil {
			return nil, err
		}
		ids = append(ids, id)
	}

	desc := fmt.Sprintf("%d Deadlines aus Fristenrechner übernommen", len(inputs))
	descPtr := &desc
	if err := insertProjectEvent(ctx, tx, projektID, userID, "deadlines_imported", "Deadlines imported", descPtr); err != nil {
		return nil, err
	}
	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("commit bulk create: %w", err)
	}

	out := make([]models.Deadline, 0, len(ids))
	for _, id := range ids {
		f, err := s.GetByID(ctx, userID, id)
		if err != nil {
			return nil, err
		}
		out = append(out, *f)
	}
	return out, nil
}

// Update applies a partial update to a Deadline.
func (s *DeadlineService) Update(ctx context.Context, userID, fristID uuid.UUID, input UpdateFristInput) (*models.Deadline, error) {
	current, err := s.GetByID(ctx, userID, fristID)
	if 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.DueDate != nil {
		due, err := time.Parse("2006-01-02", *input.DueDate)
		if err != nil {
			return nil, fmt.Errorf("%w: due_date must be YYYY-MM-DD", ErrInvalidInput)
		}
		appendSet("due_date", due)
	}
	if input.Notes != nil {
		appendSet("notes", *input.Notes)
	}
	if input.Status != nil {
		if !isValidFristStatus(*input.Status) {
			return nil, fmt.Errorf("%w: invalid status %q", ErrInvalidInput, *input.Status)
		}
		appendSet("status", *input.Status)
		if *input.Status == "completed" && current.CompletedAt == nil {
			appendSet("completed_at", time.Now().UTC())
		} else if *input.Status != "completed" {
			appendSet("completed_at", nil)
		}
	}
	if len(sets) == 0 {
		return current, nil
	}
	appendSet("updated_at", time.Now().UTC())

	args = append(args, fristID)
	query := fmt.Sprintf("UPDATE paliad.deadlines 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 deadline: %w", err)
	}

	desc := fmt.Sprintf("Deadline \u201E%s\u201C geändert", current.Title)
	descPtr := &desc
	if err := insertProjectEvent(ctx, tx, current.ProjectID, userID, "deadline_updated", "Deadline updated", descPtr); err != nil {
		return nil, err
	}
	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("commit update deadline: %w", err)
	}
	return s.GetByID(ctx, userID, fristID)
}

// Complete marks a Deadline as completed.
func (s *DeadlineService) Complete(ctx context.Context, userID, fristID uuid.UUID) (*models.Deadline, error) {
	current, err := s.GetByID(ctx, userID, fristID)
	if err != nil {
		return nil, err
	}
	if current.Status == "completed" {
		return current, nil
	}

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

	now := time.Now().UTC()
	if _, err := tx.ExecContext(ctx,
		`UPDATE paliad.deadlines
		    SET status = 'completed', completed_at = $1, updated_at = $1
		  WHERE id = $2`, now, fristID); err != nil {
		return nil, fmt.Errorf("complete deadline: %w", err)
	}
	desc := fmt.Sprintf("Deadline \u201E%s\u201C als erledigt markiert", current.Title)
	descPtr := &desc
	if err := insertProjectEvent(ctx, tx, current.ProjectID, userID, "deadline_completed", "Deadline completed", descPtr); err != nil {
		return nil, err
	}
	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("commit complete: %w", err)
	}
	return s.GetByID(ctx, userID, fristID)
}

// Delete hard-deletes a Deadline. Partner/admin only.
func (s *DeadlineService) Delete(ctx context.Context, userID, fristID uuid.UUID) error {
	user, err := s.users().GetByID(ctx, userID)
	if err != nil {
		return err
	}
	if user == nil {
		return ErrNotVisible
	}
	if user.Role != "partner" && user.Role != "admin" {
		return fmt.Errorf("%w: only partners/admins can delete Deadlines", ErrForbidden)
	}
	current, err := s.GetByID(ctx, userID, fristID)
	if 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.deadlines WHERE id = $1`, fristID); err != nil {
		return fmt.Errorf("delete deadline: %w", err)
	}
	desc := fmt.Sprintf("Deadline \u201E%s\u201C gelöscht", current.Title)
	descPtr := &desc
	if err := insertProjectEvent(ctx, tx, current.ProjectID, userID, "deadline_deleted", "Deadline deleted", descPtr); err != nil {
		return err
	}
	return tx.Commit()
}

// SummaryCounts returns traffic-light counts across the user's visible Deadlines.
type SummaryCounts struct {
	Overdue   int `json:"overdue"   db:"overdue"`
	Today     int `json:"today"     db:"today"`
	ThisWeek  int `json:"this_week" db:"this_week"`
	Upcoming  int `json:"upcoming"  db:"upcoming"`
	Completed int `json:"completed" db:"completed"`
	Total     int `json:"total"     db:"total"`
}

// SummaryCounts aggregates Deadlines by due-date bucket for the user's visible
// projects, optionally scoped to a single Project.
func (s *DeadlineService) SummaryCounts(ctx context.Context, userID uuid.UUID, projektID *uuid.UUID) (*SummaryCounts, error) {
	user, err := s.users().GetByID(ctx, userID)
	if err != nil {
		return nil, err
	}
	if user == nil {
		return &SummaryCounts{}, nil
	}
	now := time.Now().UTC()
	today := now.Truncate(24 * time.Hour)
	tomorrow := today.AddDate(0, 0, 1)
	endWeek := today.AddDate(0, 0, 7)

	conds := []string{visibilityPredicate("p")}
	args := map[string]any{
		"user_id":  userID,
		"role":     user.Role,
		"today":    today,
		"tomorrow": tomorrow,
		"endweek":  endWeek,
	}
	if projektID != nil {
		conds = append(conds, `f.project_id = :project_id`)
		args["project_id"] = *projektID
	}

	query := `
		SELECT
		  COUNT(*) FILTER (WHERE f.status = 'pending'  AND f.due_date < :today)                           AS overdue,
		  COUNT(*) FILTER (WHERE f.status = 'pending'  AND f.due_date >= :today AND f.due_date < :tomorrow) AS today,
		  COUNT(*) FILTER (WHERE f.status = 'pending'  AND f.due_date >= :today AND f.due_date < :endweek) AS this_week,
		  COUNT(*) FILTER (WHERE f.status = 'pending'  AND f.due_date >= :endweek)                        AS upcoming,
		  COUNT(*) FILTER (WHERE f.status = 'completed')                                                  AS completed,
		  COUNT(*)                                                                                          AS total
		  FROM paliad.deadlines f
		  JOIN paliad.projects p ON p.id = f.project_id
		 WHERE ` + strings.Join(conds, " AND ")

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

	var c SummaryCounts
	if err := stmt.GetContext(ctx, &c, args); err != nil {
		return nil, fmt.Errorf("deadline summary: %w", err)
	}
	return &c, nil
}

// insert performs one INSERT in its own transaction.
func (s *DeadlineService) insert(ctx context.Context, userID, projektID uuid.UUID, input CreateFristInput) (uuid.UUID, error) {
	tx, err := s.db.BeginTxx(ctx, nil)
	if err != nil {
		return uuid.Nil, fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback()

	id, err := s.insertTx(ctx, tx, userID, projektID, input)
	if err != nil {
		return uuid.Nil, err
	}

	desc := fmt.Sprintf("Deadline \u201E%s\u201C angelegt", strings.TrimSpace(input.Title))
	descPtr := &desc
	if err := insertProjectEvent(ctx, tx, projektID, userID, "deadline_created", "Deadline created", descPtr); err != nil {
		return uuid.Nil, err
	}
	if err := tx.Commit(); err != nil {
		return uuid.Nil, fmt.Errorf("commit insert deadline: %w", err)
	}
	return id, nil
}

// insertTx writes one deadlines row in an existing transaction.
func (s *DeadlineService) insertTx(ctx context.Context, tx *sqlx.Tx, userID, projektID uuid.UUID, input CreateFristInput) (uuid.UUID, error) {
	title := strings.TrimSpace(input.Title)
	if title == "" {
		return uuid.Nil, fmt.Errorf("%w: title is required", ErrInvalidInput)
	}
	if input.DueDate == "" {
		return uuid.Nil, fmt.Errorf("%w: due_date is required", ErrInvalidInput)
	}
	due, err := time.Parse("2006-01-02", input.DueDate)
	if err != nil {
		return uuid.Nil, fmt.Errorf("%w: due_date must be YYYY-MM-DD", ErrInvalidInput)
	}
	var orig *time.Time
	if input.OriginalDueDate != nil && *input.OriginalDueDate != "" {
		o, err := time.Parse("2006-01-02", *input.OriginalDueDate)
		if err != nil {
			return uuid.Nil, fmt.Errorf("%w: original_due_date must be YYYY-MM-DD", ErrInvalidInput)
		}
		orig = &o
	}
	source := input.Source
	if source == "" {
		source = "manual"
	}

	id := uuid.New()
	now := time.Now().UTC()
	if _, err := tx.ExecContext(ctx,
		`INSERT INTO paliad.deadlines
		   (id, project_id, title, description, due_date, original_due_date,
		    source, rule_id, status, notes, created_by, created_at, updated_at)
		 VALUES ($1, $2, $3, $4, $5, $6, $7, $8, 'pending', $9, $10, $11, $11)`,
		id, projektID, title, input.Description, due, orig,
		source, input.RuleID, input.Notes, userID, now,
	); err != nil {
		return uuid.Nil, fmt.Errorf("insert deadline: %w", err)
	}
	return id, nil
}

// parentProjectID resolves a Deadline's parent Project ID without a visibility
// check. Internal only — callers must then gate via ProjectService.GetByID.
func (s *DeadlineService) parentProjectID(ctx context.Context, fristID uuid.UUID) (uuid.UUID, error) {
	var projektID uuid.UUID
	err := s.db.GetContext(ctx, &projektID,
		`SELECT project_id FROM paliad.deadlines WHERE id = $1`, fristID)
	if errors.Is(err, sql.ErrNoRows) {
		return uuid.Nil, ErrNotVisible
	}
	if err != nil {
		return uuid.Nil, fmt.Errorf("lookup deadline parent: %w", err)
	}
	return projektID, nil
}

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

func isValidFristStatus(st string) bool {
	switch st {
	case "pending", "completed", "cancelled", "waived":
		return true
	}
	return false
}