feat: review open answers in the admin and pick a grader per quiz

- Do oceny admin screen (golem15.quizzes.reviews) over the open answers,
  with a read-only context partial, score and comment virtual fields saved
  through SetScore, confirm and regrade record actions, bulk confirm
- open question type, rubric and max_length in the question form; grader
  dropdown on the quiz form from the grader registry
- Review model with quiz, status and student filters

models/filters.go

@@ -2,6 +2,7 @@ package models
 
 import (
 	"encoding/hex"
+	"slices"
 	"strconv"
 	"strings"
 
@@ -22,6 +23,8 @@ const (
 	ScopeByQuiz     = "filterByQuiz"
 	ScopeByCategory = "filterByCategory"
 	ScopeByType     = "filterByType"
+	ScopeByStatus   = "filterByStatus"
+	ScopeByStudent  = "filterByStudent"
 )
 
 var (
@@ -31,6 +34,8 @@ var (
 	_ pact.FilterOptions = Answer{}
 	_ pact.FilterScope   = Attempt{}
 	_ pact.FilterOptions = Attempt{}
+	_ pact.FilterScope   = Review{}
+	_ pact.FilterOptions = Review{}
 )
 
 // FilterScopes lists the admin list scopes of questions.
@@ -75,6 +80,7 @@ func (Question) FilterOptions(scope string) []pact.Option {
 			{Value: TypeSingle, Label: "golem15.quizzes::lang.questions.type_single"},
 			{Value: TypeMultiple, Label: "golem15.quizzes::lang.questions.type_multiple"},
 			{Value: TypeSelfCheck, Label: "golem15.quizzes::lang.questions.type_self_check"},
+			{Value: TypeOpen, Label: "golem15.quizzes::lang.questions.type_open"},
 		}
 	}
 	return nil
@@ -121,6 +127,54 @@ func (Attempt) FilterOptions(scope string) []pact.Option {
 	return nil
 }
 
+// FilterScopes lists the admin list scopes of the review screen.
+func (Review) FilterScopes() []string { return []string{ScopeByQuiz, ScopeByStatus, ScopeByStudent} }
+
+// FilterScope narrows the review list to the open answers of the chosen
+// quizzes, grading statuses or students.
+func (Review) FilterScope(name string, db *gorm.DB, value any) *gorm.DB {
+	values := filterValues(value)
+	if db == nil || len(values) == 0 {
+		return db
+	}
+	switch name {
+	case ScopeByQuiz:
+		return db.Where("golem15_quizzes_attempt_answers.question_id IN (SELECT id FROM golem15_quizzes_questions WHERE quiz_id IN ?)", ids(values))
+	case ScopeByStatus:
+		statuses := make([]string, 0, len(values))
+		for _, v := range values {
+			if slices.Contains(GradingStatuses, v) {
+				statuses = append(statuses, v)
+			}
+		}
+		if len(statuses) == 0 {
+			return db.Where("1 = 0")
+		}
+		return db.Where("golem15_quizzes_attempt_answers.grading_status IN ?", statuses)
+	case ScopeByStudent:
+		return db.Where("golem15_quizzes_attempt_answers.attempt_id IN (SELECT id FROM golem15_quizzes_attempts WHERE user_id IN ?)", ids(values))
+	}
+	return db
+}
+
+// FilterOptions serves the quizzes, the grading statuses and the students
+// who have open answers.
+func (Review) FilterOptions(scope string) []pact.Option {
+	switch scope {
+	case ScopeByQuiz:
+		return quizOptions()
+	case ScopeByStatus:
+		out := make([]pact.Option, 0, len(GradingStatuses))
+		for _, status := range GradingStatuses {
+			out = append(out, pact.Option{Value: status, Label: "golem15.quizzes::lang.reviews.status_" + status})
+		}
+		return out
+	case ScopeByStudent:
+		return studentOptions()
+	}
+	return nil
+}
+
 func filterDB() *gorm.DB {
 	if FilterDB == nil {
 		return nil
@@ -144,6 +198,32 @@ func quizOptions() []pact.Option {
 	return out
 }
 
+// studentOptions lists the users with at least one open answer, by email.
+func studentOptions() []pact.Option {
+	db := filterDB()
+	if db == nil {
+		return nil
+	}
+	var rows []struct {
+		ID    uint
+		Email string
+	}
+	err := db.Raw(`SELECT DISTINCT u.id AS id, COALESCE(u.email, '') AS email
+FROM users u
+JOIN golem15_quizzes_attempts a ON a.user_id = u.id
+JOIN golem15_quizzes_attempt_answers aa ON aa.attempt_id = a.id
+WHERE aa.grading_status IS NOT NULL
+ORDER BY email, id`).Scan(&rows).Error
+	if err != nil {
+		return nil
+	}
+	out := make([]pact.Option, 0, len(rows))
+	for _, r := range rows {
+		out = append(out, pact.Option{Value: strconv.FormatUint(uint64(r.ID), 10), Label: r.Email})
+	}
+	return out
+}
+
 func categoryOptions() []pact.Option {
 	db := filterDB()
 	if db == nil {

models/questions/fields.yaml

@@ -15,6 +15,7 @@ fields:
             single: golem15.quizzes::lang.questions.type_single
             multiple: golem15.quizzes::lang.questions.type_multiple
             self_check: golem15.quizzes::lang.questions.type_self_check
+            open: golem15.quizzes::lang.questions.type_open
     text:
         label: golem15.quizzes::lang.questions.text
         type: textarea
@@ -35,6 +36,16 @@ fields:
         type: textarea
         size: small
         comment: golem15.quizzes::lang.questions.answer_text_comment
+    rubric:
+        label: golem15.quizzes::lang.questions.rubric
+        type: textarea
+        size: small
+        comment: golem15.quizzes::lang.questions.rubric_comment
+    max_length:
+        label: golem15.quizzes::lang.questions.max_length
+        type: number
+        span: left
+        comment: golem15.quizzes::lang.questions.max_length_comment
     explanation:
         label: golem15.quizzes::lang.questions.explanation
         type: textarea

models/quizzes/columns.yaml

@@ -10,6 +10,8 @@ columns:
         searchable: true
     mode:
         label: golem15.quizzes::lang.quizzes.mode
+    grader:
+        label: golem15.quizzes::lang.quizzes.grader
     is_published:
         label: golem15.quizzes::lang.quizzes.is_published
         type: switch

models/quizzes/fields.yaml

@@ -65,3 +65,10 @@ fields:
         type: number
         span: left
         comment: golem15.quizzes::lang.quizzes.max_attempts_comment
+    grader:
+        label: golem15.quizzes::lang.quizzes.grader
+        type: dropdown
+        span: right
+        default: manual
+        options: getGraderOptions
+        comment: golem15.quizzes::lang.quizzes.grader_comment

models/review.go

@@ -0,0 +1,60 @@
+package models
+
+import "time"
+
+// ReviewMorphName is Review's morph type. Review shares its table with
+// AttemptAnswer, so it names itself: two models listed in Models() with the
+// same morph type would stop deferred:purge.
+const ReviewMorphName = "golem15.quizzes.review"
+
+// Review is an open answer as the admin "Do oceny" screen shows it. It reads
+// the same golem15_quizzes_attempt_answers table as AttemptAnswer, which
+// keeps its empty Fillable for the API; the admin never writes a column
+// through it either. The owner's score and comment are form virtual fields
+// that the controller saves through the review service.
+type Review struct {
+	ID                uint       `gorm:"column:id;primaryKey"`
+	AttemptID         uint       `gorm:"column:attempt_id"`
+	QuestionID        uint       `gorm:"column:question_id"`
+	TextAnswer        *string    `gorm:"column:text_answer"`
+	GradingStatus     *string    `gorm:"column:grading_status"`
+	GradingSeq        int        `gorm:"column:grading_seq"`
+	GradingAttempts   int        `gorm:"column:grading_attempts"`
+	Grader            *string    `gorm:"column:grader"`
+	GraderPoints      *float64   `gorm:"column:grader_points"`
+	GraderFeedback    *string    `gorm:"column:grader_feedback"`
+	GradingError      *string    `gorm:"column:grading_error"`
+	GradedAt          *time.Time `gorm:"column:graded_at"`
+	Points            float64    `gorm:"column:points"`
+	IsCorrect         bool       `gorm:"column:is_correct"`
+	ReviewComment     *string    `gorm:"column:review_comment"`
+	ReviewedAt        *time.Time `gorm:"column:reviewed_at"`
+	ReviewedByUserID  *uint      `gorm:"column:reviewed_by_user_id"`
+	ReviewedByAdminID *uint      `gorm:"column:reviewed_by_admin_id"`
+	CreatedAt         time.Time  `gorm:"column:created_at"`
+	UpdatedAt         time.Time  `gorm:"column:updated_at"`
+
+	Question *Question `gorm:"foreignKey:QuestionID"`
+	Attempt  *Attempt  `gorm:"foreignKey:AttemptID"`
+}
+
+// TableName is the attempt answers table.
+func (Review) TableName() string { return "golem15_quizzes_attempt_answers" }
+
+// MorphName keeps Review apart from AttemptAnswer, which owns the table.
+func (Review) MorphName() string { return ReviewMorphName }
+
+// Fillable is empty: the admin form saves no column of an answer.
+func (Review) Fillable() []string { return []string{} }
+
+// Rules are empty: the controller's FormRules check the virtual fields.
+func (Review) Rules() map[string]string { return map[string]string{} }
+
+// ReviewStatus reports the grading status, "" when the row is not an open
+// answer.
+func (r Review) ReviewStatus() string {
+	if r.GradingStatus == nil {
+		return ""
+	}
+	return *r.GradingStatus
+}

models/reviews/columns.yaml

@@ -0,0 +1,21 @@
+columns:
+    question:
+        label: golem15.quizzes::lang.reviews.question
+        relation: question
+        select: text
+        searchable: true
+    grading_status:
+        label: golem15.quizzes::lang.reviews.status
+    grader_points:
+        label: golem15.quizzes::lang.reviews.grader_points
+    points:
+        label: golem15.quizzes::lang.reviews.points
+    graded_at:
+        label: golem15.quizzes::lang.reviews.graded_at
+        type: datetime
+    reviewed_at:
+        label: golem15.quizzes::lang.reviews.reviewed_at
+        type: datetime
+    updated_at:
+        label: golem15.quizzes::lang.common.updated_at
+        type: datetime

models/reviews/fields.yaml

@@ -0,0 +1,19 @@
+# The answer itself is read-only: the review_context partial shows it from a
+# curated view model. review_points and review_comment are virtual fields the
+# controller saves through the review service (SetScore).
+fields:
+    review_context:
+        label: golem15.quizzes::lang.reviews.context
+        type: partial
+        path: review_context
+        span: full
+    review_points:
+        label: golem15.quizzes::lang.reviews.review_points
+        type: number
+        span: left
+        comment: golem15.quizzes::lang.reviews.review_points_comment
+    review_comment:
+        label: golem15.quizzes::lang.reviews.review_comment
+        type: textarea
+        size: small
+        comment: golem15.quizzes::lang.reviews.review_comment_comment