package postgres

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

	"github.com/lib/pq"
	"github.com/orchard9/rdev/internal/domain"
	"github.com/orchard9/rdev/internal/port"
)

// QuestionRepository implements port.QuestionRepository using PostgreSQL.
type QuestionRepository struct {
	db *sql.DB
}

// NewQuestionRepository creates a new PostgreSQL question repository.
func NewQuestionRepository(db *sql.DB) *QuestionRepository {
	return &QuestionRepository{db: db}
}

// Ensure QuestionRepository implements port.QuestionRepository at compile time.
var _ port.QuestionRepository = (*QuestionRepository)(nil)

// CreateQuestion creates a new question.
func (r *QuestionRepository) CreateQuestion(ctx context.Context, question *domain.Question) error {
	metadataJSON, err := json.Marshal(question.Metadata)
	if err != nil {
		return fmt.Errorf("marshal metadata: %w", err)
	}

	err = r.db.QueryRowContext(ctx, `
		INSERT INTO questions (conversation_id, project_id, question_type, text, choices, metadata)
		VALUES ($1, $2, $3, $4, $5, $6)
		RETURNING id, created_at
	`, question.ConversationID, question.ProjectID, question.Type, question.Text, pq.Array(question.Choices), metadataJSON).Scan(
		&question.ID,
		&question.CreatedAt,
	)
	if err != nil {
		return fmt.Errorf("create question: %w", err)
	}

	return nil
}

// GetQuestion retrieves a question by ID.
func (r *QuestionRepository) GetQuestion(ctx context.Context, id domain.QuestionID) (*domain.Question, error) {
	var question domain.Question
	var answer sql.NullString
	var answeredAt sql.NullTime
	var metadataJSON []byte

	err := r.db.QueryRowContext(ctx, `
		SELECT id, conversation_id, project_id, question_type, text, choices, answer, answer_choices, metadata, created_at, answered_at
		FROM questions
		WHERE id = $1
	`, id).Scan(
		&question.ID,
		&question.ConversationID,
		&question.ProjectID,
		&question.Type,
		&question.Text,
		pq.Array(&question.Choices),
		&answer,
		pq.Array(&question.AnswerChoices),
		&metadataJSON,
		&question.CreatedAt,
		&answeredAt,
	)
	if err == sql.ErrNoRows {
		return nil, domain.ErrQuestionNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("get question: %w", err)
	}

	if answer.Valid {
		question.Answer = &answer.String
	}
	if answeredAt.Valid {
		question.AnsweredAt = &answeredAt.Time
	}

	if len(metadataJSON) > 0 {
		if err := json.Unmarshal(metadataJSON, &question.Metadata); err != nil {
			return nil, fmt.Errorf("unmarshal metadata: %w", err)
		}
	}

	return &question, nil
}

// ListUnansweredQuestions returns all unanswered questions for a project.
func (r *QuestionRepository) ListUnansweredQuestions(ctx context.Context, projectID string) ([]*domain.Question, error) {
	rows, err := r.db.QueryContext(ctx, `
		SELECT id, conversation_id, project_id, question_type, text, choices, answer, answer_choices, metadata, created_at, answered_at
		FROM questions
		WHERE project_id = $1 AND answered_at IS NULL
		ORDER BY created_at DESC
	`, projectID)
	if err != nil {
		return nil, fmt.Errorf("list unanswered questions: %w", err)
	}
	defer rows.Close()

	var questions []*domain.Question
	for rows.Next() {
		var question domain.Question
		var answer sql.NullString
		var answeredAt sql.NullTime
		var metadataJSON []byte

		if err := rows.Scan(
			&question.ID,
			&question.ConversationID,
			&question.ProjectID,
			&question.Type,
			&question.Text,
			pq.Array(&question.Choices),
			&answer,
			pq.Array(&question.AnswerChoices),
			&metadataJSON,
			&question.CreatedAt,
			&answeredAt,
		); err != nil {
			return nil, fmt.Errorf("scan question: %w", err)
		}

		if answer.Valid {
			question.Answer = &answer.String
		}
		if answeredAt.Valid {
			question.AnsweredAt = &answeredAt.Time
		}

		if len(metadataJSON) > 0 {
			if err := json.Unmarshal(metadataJSON, &question.Metadata); err != nil {
				return nil, fmt.Errorf("unmarshal metadata: %w", err)
			}
		}

		questions = append(questions, &question)
	}

	return questions, rows.Err()
}

// ListQuestionsByConversation returns all questions for a conversation.
func (r *QuestionRepository) ListQuestionsByConversation(ctx context.Context, conversationID domain.ConversationID) ([]*domain.Question, error) {
	rows, err := r.db.QueryContext(ctx, `
		SELECT id, conversation_id, project_id, question_type, text, choices, answer, answer_choices, metadata, created_at, answered_at
		FROM questions
		WHERE conversation_id = $1
		ORDER BY created_at DESC
	`, conversationID)
	if err != nil {
		return nil, fmt.Errorf("list questions by conversation: %w", err)
	}
	defer rows.Close()

	var questions []*domain.Question
	for rows.Next() {
		var question domain.Question
		var answer sql.NullString
		var answeredAt sql.NullTime
		var metadataJSON []byte

		if err := rows.Scan(
			&question.ID,
			&question.ConversationID,
			&question.ProjectID,
			&question.Type,
			&question.Text,
			pq.Array(&question.Choices),
			&answer,
			pq.Array(&question.AnswerChoices),
			&metadataJSON,
			&question.CreatedAt,
			&answeredAt,
		); err != nil {
			return nil, fmt.Errorf("scan question: %w", err)
		}

		if answer.Valid {
			question.Answer = &answer.String
		}
		if answeredAt.Valid {
			question.AnsweredAt = &answeredAt.Time
		}

		if len(metadataJSON) > 0 {
			if err := json.Unmarshal(metadataJSON, &question.Metadata); err != nil {
				return nil, fmt.Errorf("unmarshal metadata: %w", err)
			}
		}

		questions = append(questions, &question)
	}

	return questions, rows.Err()
}

// AnswerQuestion records an answer to a question.
func (r *QuestionRepository) AnswerQuestion(ctx context.Context, id domain.QuestionID, answer *string, answerChoices []string) error {
	now := time.Now()

	result, err := r.db.ExecContext(ctx, `
		UPDATE questions
		SET answer = $1, answer_choices = $2, answered_at = $3
		WHERE id = $4
	`, answer, pq.Array(answerChoices), now, id)
	if err != nil {
		return fmt.Errorf("answer question: %w", err)
	}

	rows, err := result.RowsAffected()
	if err != nil {
		return fmt.Errorf("rows affected: %w", err)
	}
	if rows == 0 {
		return domain.ErrQuestionNotFound
	}

	return nil
}

// DeleteQuestion deletes a question.
func (r *QuestionRepository) DeleteQuestion(ctx context.Context, id domain.QuestionID) error {
	result, err := r.db.ExecContext(ctx, `
		DELETE FROM questions WHERE id = $1
	`, id)
	if err != nil {
		return fmt.Errorf("delete question: %w", err)
	}

	rows, err := result.RowsAffected()
	if err != nil {
		return fmt.Errorf("rows affected: %w", err)
	}
	if rows == 0 {
		return domain.ErrQuestionNotFound
	}

	return nil
}