package interview

import (
	"context"
	"encoding/json"
	"fmt"

	"github.com/jackc/pgx/v5/pgxpool"
)

type PostgresStore struct {
	pool *pgxpool.Pool
}

func NewPostgresStore(pool *pgxpool.Pool) *PostgresStore {
	return &PostgresStore{pool: pool}
}

func toJSON(v any) string {
	b, _ := json.Marshal(v)
	return string(b)
}

func (s *PostgresStore) Create(session Session) (Session, error) {
	_, err := s.pool.Exec(context.Background(),
		`INSERT INTO interview_sessions (id, user_id, target_role, stack, interview_timeline, questions, answers, created_at)
		 VALUES ($1, $2, $3, $4::jsonb, $5, $6::jsonb, $7::jsonb, $8)
		 ON CONFLICT (id) DO UPDATE SET
		   user_id = EXCLUDED.user_id,
		   target_role = EXCLUDED.target_role,
		   stack = EXCLUDED.stack,
		   interview_timeline = EXCLUDED.interview_timeline,
		   questions = EXCLUDED.questions,
		   answers = EXCLUDED.answers,
		   created_at = EXCLUDED.created_at`,
		session.ID, session.UserID, session.TargetRole, toJSON(session.Stack),
		session.InterviewTimeline, toJSON(session.Questions), toJSON(session.Answers), session.CreatedAt,
	)
	if err != nil {
		return Session{}, fmt.Errorf("insert session: %w", err)
	}
	return session, nil
}

func (s *PostgresStore) Get(id string) (Session, error) {
	var session Session
	var stackJSON, questionsJSON, answersJSON string

	err := s.pool.QueryRow(context.Background(),
		`SELECT id, user_id, target_role, stack, interview_timeline, questions, answers, created_at
		 FROM interview_sessions WHERE id = $1`, id,
	).Scan(&session.ID, &session.UserID, &session.TargetRole, &stackJSON,
		&session.InterviewTimeline, &questionsJSON, &answersJSON, &session.CreatedAt)
	if err != nil {
		return Session{}, ErrSessionNotFound
	}

	json.Unmarshal([]byte(stackJSON), &session.Stack)
	json.Unmarshal([]byte(questionsJSON), &session.Questions)
	json.Unmarshal([]byte(answersJSON), &session.Answers)
	return session, nil
}

func (s *PostgresStore) Update(session Session) (Session, error) {
	_, err := s.pool.Exec(context.Background(),
		`UPDATE interview_sessions SET
		   user_id = $2, target_role = $3, stack = $4::jsonb, interview_timeline = $5,
		   questions = $6::jsonb, answers = $7::jsonb, created_at = $8
		 WHERE id = $1`,
		session.ID, session.UserID, session.TargetRole, toJSON(session.Stack),
		session.InterviewTimeline, toJSON(session.Questions), toJSON(session.Answers), session.CreatedAt,
	)
	if err != nil {
		return Session{}, fmt.Errorf("update session: %w", err)
	}
	return session, nil
}