package db

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

type CreateSessionParams struct {
	UserID    int64
	TokenHash string
	ExpiresAt time.Time
	IPAddress string
	UserAgent string
}

func (r *SessionRepository) Create(ctx context.Context, params CreateSessionParams) (*Session, error) {
	result, err := r.q.ExecContext(
		ctx,
		`INSERT INTO sessions (user_id, token_hash, expires_at, ip_address, user_agent) VALUES (?, ?, ?, ?, ?)`,
		params.UserID,
		params.TokenHash,
		formatTimestamp(params.ExpiresAt),
		params.IPAddress,
		params.UserAgent,
	)
	if err != nil {
		return nil, fmt.Errorf("insert session: %w", err)
	}

	sessionID, err := result.LastInsertId()
	if err != nil {
		return nil, fmt.Errorf("load inserted session id: %w", err)
	}

	return r.GetByID(ctx, sessionID)
}

func (r *SessionRepository) GetByID(ctx context.Context, id int64) (*Session, error) {
	session, err := scanSession(r.q.QueryRowContext(
		ctx,
		`SELECT id, user_id, token_hash, expires_at, last_seen_at, invalidated_at, ip_address, user_agent, created_at
		FROM sessions
		WHERE id = ?`,
		id,
	))
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrNotFound
		}

		return nil, fmt.Errorf("scan session by id: %w", err)
	}

	return session, nil
}

func (r *SessionRepository) GetActiveWithUserByTokenHash(ctx context.Context, tokenHash string, now time.Time) (*SessionWithUser, error) {
	record, err := scanSessionWithUser(r.q.QueryRowContext(
		ctx,
		`SELECT
			s.id,
			s.user_id,
			s.token_hash,
			s.expires_at,
			s.last_seen_at,
			s.invalidated_at,
			s.ip_address,
			s.user_agent,
			s.created_at,
			u.id,
			u.email,
			u.password_hash,
			u.role,
			u.is_active,
			u.created_at,
			u.updated_at,
			u.last_login_at
		FROM sessions AS s
		INNER JOIN users AS u ON u.id = s.user_id
		WHERE s.token_hash = ?
			AND s.invalidated_at IS NULL
			AND s.expires_at > ?
			AND u.is_active = 1
		LIMIT 1`,
		tokenHash,
		formatTimestamp(now),
	))
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrNotFound
		}

		return nil, fmt.Errorf("scan active session by token hash: %w", err)
	}

	return record, nil
}

func (r *SessionRepository) Touch(ctx context.Context, sessionID int64, seenAt time.Time) error {
	result, err := r.q.ExecContext(
		ctx,
		`UPDATE sessions SET last_seen_at = ? WHERE id = ?`,
		formatTimestamp(seenAt),
		sessionID,
	)
	if err != nil {
		return fmt.Errorf("update session last_seen_at: %w", err)
	}

	rowsAffected, err := result.RowsAffected()
	if err != nil {
		return fmt.Errorf("read affected session rows: %w", err)
	}

	if rowsAffected == 0 {
		return ErrNotFound
	}

	return nil
}

func (r *SessionRepository) InvalidateByTokenHash(ctx context.Context, tokenHash string, invalidatedAt time.Time) error {
	result, err := r.q.ExecContext(
		ctx,
		`UPDATE sessions
		SET invalidated_at = ?
		WHERE token_hash = ?
			AND invalidated_at IS NULL`,
		formatTimestamp(invalidatedAt),
		tokenHash,
	)
	if err != nil {
		return fmt.Errorf("invalidate session by token hash: %w", err)
	}

	rowsAffected, err := result.RowsAffected()
	if err != nil {
		return fmt.Errorf("read invalidated session rows: %w", err)
	}

	if rowsAffected == 0 {
		return ErrNotFound
	}

	return nil
}

func scanSession(scanner rowScanner) (*Session, error) {
	var (
		session          Session
		expiresAtRaw     string
		lastSeenAtRaw    sql.NullString
		invalidatedAtRaw sql.NullString
		createdAtRaw     string
	)

	if err := scanner.Scan(
		&session.ID,
		&session.UserID,
		&session.TokenHash,
		&expiresAtRaw,
		&lastSeenAtRaw,
		&invalidatedAtRaw,
		&session.IPAddress,
		&session.UserAgent,
		&createdAtRaw,
	); err != nil {
		return nil, err
	}

	expiresAt, err := parseTimestamp(expiresAtRaw)
	if err != nil {
		return nil, fmt.Errorf("parse session expires_at: %w", err)
	}

	lastSeenAt, err := parseNullableTimestamp(lastSeenAtRaw)
	if err != nil {
		return nil, fmt.Errorf("parse session last_seen_at: %w", err)
	}

	invalidatedAt, err := parseNullableTimestamp(invalidatedAtRaw)
	if err != nil {
		return nil, fmt.Errorf("parse session invalidated_at: %w", err)
	}

	createdAt, err := parseTimestamp(createdAtRaw)
	if err != nil {
		return nil, fmt.Errorf("parse session created_at: %w", err)
	}

	session.ExpiresAt = expiresAt
	session.LastSeenAt = lastSeenAt
	session.InvalidatedAt = invalidatedAt
	session.CreatedAt = createdAt

	return &session, nil
}

func scanSessionWithUser(scanner rowScanner) (*SessionWithUser, error) {
	var (
		record             SessionWithUser
		sessionExpiresRaw  string
		sessionLastSeenRaw sql.NullString
		sessionInvalidRaw  sql.NullString
		sessionCreatedRaw  string
		userRole           string
		userIsActive       int
		userCreatedRaw     string
		userUpdatedRaw     string
		userLastLoginRaw   sql.NullString
	)

	if err := scanner.Scan(
		&record.Session.ID,
		&record.Session.UserID,
		&record.Session.TokenHash,
		&sessionExpiresRaw,
		&sessionLastSeenRaw,
		&sessionInvalidRaw,
		&record.Session.IPAddress,
		&record.Session.UserAgent,
		&sessionCreatedRaw,
		&record.User.ID,
		&record.User.Email,
		&record.User.PasswordHash,
		&userRole,
		&userIsActive,
		&userCreatedRaw,
		&userUpdatedRaw,
		&userLastLoginRaw,
	); err != nil {
		return nil, err
	}

	sessionExpiresAt, err := parseTimestamp(sessionExpiresRaw)
	if err != nil {
		return nil, fmt.Errorf("parse joined session expires_at: %w", err)
	}

	sessionLastSeenAt, err := parseNullableTimestamp(sessionLastSeenRaw)
	if err != nil {
		return nil, fmt.Errorf("parse joined session last_seen_at: %w", err)
	}

	sessionInvalidatedAt, err := parseNullableTimestamp(sessionInvalidRaw)
	if err != nil {
		return nil, fmt.Errorf("parse joined session invalidated_at: %w", err)
	}

	sessionCreatedAt, err := parseTimestamp(sessionCreatedRaw)
	if err != nil {
		return nil, fmt.Errorf("parse joined session created_at: %w", err)
	}

	userCreatedAt, err := parseTimestamp(userCreatedRaw)
	if err != nil {
		return nil, fmt.Errorf("parse joined user created_at: %w", err)
	}

	userUpdatedAt, err := parseTimestamp(userUpdatedRaw)
	if err != nil {
		return nil, fmt.Errorf("parse joined user updated_at: %w", err)
	}

	userLastLoginAt, err := parseNullableTimestamp(userLastLoginRaw)
	if err != nil {
		return nil, fmt.Errorf("parse joined user last_login_at: %w", err)
	}

	record.Session.ExpiresAt = sessionExpiresAt
	record.Session.LastSeenAt = sessionLastSeenAt
	record.Session.InvalidatedAt = sessionInvalidatedAt
	record.Session.CreatedAt = sessionCreatedAt
	record.User.Role = UserRole(userRole)
	record.User.IsActive = userIsActive == 1
	record.User.CreatedAt = userCreatedAt
	record.User.UpdatedAt = userUpdatedAt
	record.User.LastLoginAt = userLastLoginAt

	return &record, nil
}