package auth

import (
	"context"
	"errors"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
)

// Invite is a pending company invite row (plaintext token returned once at creation; hashed at rest).
type Invite struct {
	ID        uuid.UUID `json:"id"`
	CompanyID uuid.UUID `json:"company_id"`
	Email     string    `json:"email"`
	Role      string    `json:"role"`
	ExpiresAt time.Time `json:"expires_at"`
}

func normalizeInviteRole(role string) string {
	role = strings.TrimSpace(strings.ToLower(role))
	if role == "admin" {
		return "admin"
	}
	return "member"
}

// NormalizeMembershipRole maps invite/membership role strings to admin|member.
// Unknown values collapse to member (safe default for invites).
func NormalizeMembershipRole(role string) string {
	return normalizeInviteRole(role)
}

// ErrInvalidMembershipRole is returned when a role is not exactly admin|member.
var ErrInvalidMembershipRole = errors.New("invalid membership role")

// ParseMembershipRole accepts only admin|member (case-insensitive). Unlike
// NormalizeMembershipRole it does not coerce unknown values to member — use for
// PATCH/role updates where coercion would silently demote admins.
func ParseMembershipRole(role string) (string, error) {
	role = strings.TrimSpace(strings.ToLower(role))
	switch role {
	case "admin", "member":
		return role, nil
	default:
		return "", ErrInvalidMembershipRole
	}
}

// preferMembershipRole keeps admin on invite accept conflict (never demote admin→member).
// Mirrors AcceptInvite ON CONFLICT role CASE.
func preferMembershipRole(existing, invited string) string {
	if existing == "admin" {
		return "admin"
	}
	return normalizeInviteRole(invited)
}

// HashInviteToken returns the SHA-256 hex digest stored in invites.token (same construction as API keys).
func HashInviteToken(raw string) string {
	return HashAPIKey(raw)
}

// IsSyntheticLegacyEmail reports Clerk-missing synthetic addresses that must not receive invites.
func IsSyntheticLegacyEmail(email string) bool {
	email = strings.ToLower(strings.TrimSpace(email))
	return strings.HasSuffix(email, "@legacy.local")
}

// EmailsEqual compares emails case-insensitively after trim.
func EmailsEqual(a, b string) bool {
	return strings.EqualFold(strings.TrimSpace(a), strings.TrimSpace(b))
}

// ResolveInviteEmail returns the invitee email for a pending, unexpired invite token.
func (s *Service) ResolveInviteEmail(ctx context.Context, token string) (string, error) {
	token = strings.TrimSpace(token)
	if token == "" {
		return "", ErrInviteInvalid
	}
	var (
		email      string
		expiresAt  time.Time
		acceptedAt *time.Time
	)
	tokenHash := HashInviteToken(token)
	err := s.Pool.QueryRow(ctx, `
		SELECT email, expires_at, accepted_at
		FROM invites
		WHERE token = $1 OR token = $2
		ORDER BY CASE WHEN token = $1 THEN 0 ELSE 1 END
		LIMIT 1`, tokenHash, token).Scan(&email, &expiresAt, &acceptedAt)
	if errors.Is(err, pgx.ErrNoRows) || (acceptedAt != nil) || time.Now().After(expiresAt) {
		return "", ErrInviteInvalid
	}
	if err != nil {
		return "", err
	}
	return strings.ToLower(strings.TrimSpace(email)), nil
}

// SetPasswordInvite is a one-time accept-invite token for a migrated user (plaintext returned once).
type SetPasswordInvite struct {
	InviteID  uuid.UUID
	UserID    uuid.UUID
	Email     string
	CompanyID uuid.UUID
	Role      string
	Token     string
	ExpiresAt time.Time
}

// CreateInvite inserts a pending invite (token hashed at rest) and returns the plaintext token once.
func (s *Service) CreateInvite(ctx context.Context, companyID, invitedBy uuid.UUID, email, role string) (Invite, string, error) {
	email = strings.ToLower(strings.TrimSpace(email))
	if email == "" {
		return Invite{}, "", ErrEmailRequired
	}
	role = normalizeInviteRole(role)
	token, err := RandomToken(24)
	if err != nil {
		return Invite{}, "", err
	}
	expires := time.Now().UTC().Add(7 * 24 * time.Hour)
	var inv Invite
	err = s.Pool.QueryRow(ctx, `
		INSERT INTO invites (company_id, email, role, token, invited_by, expires_at)
		VALUES ($1, $2, $3, $4, $5, $6)
		RETURNING id, company_id, email, role, expires_at`,
		companyID, email, role, HashInviteToken(token), invitedBy, expires,
	).Scan(&inv.ID, &inv.CompanyID, &inv.Email, &inv.Role, &inv.ExpiresAt)
	if err != nil {
		return Invite{}, "", err
	}
	return inv, token, nil
}

// ListPendingInvites returns unaccepted, unexpired invites for a company.
func (s *Service) ListPendingInvites(ctx context.Context, companyID uuid.UUID, limit, offset int) ([]Invite, int64, error) {
	const where = `company_id = $1 AND accepted_at IS NULL AND expires_at > now()`
	var total int64
	if err := s.Pool.QueryRow(ctx, `SELECT count(*) FROM invites WHERE `+where, companyID).Scan(&total); err != nil {
		return nil, 0, err
	}
	rows, err := s.Pool.Query(ctx, `
		SELECT id, company_id, email, role, expires_at
		FROM invites
		WHERE `+where+`
		ORDER BY created_at DESC LIMIT $2 OFFSET $3`, companyID, limit, offset)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()
	var out []Invite
	for rows.Next() {
		var inv Invite
		if err := rows.Scan(&inv.ID, &inv.CompanyID, &inv.Email, &inv.Role, &inv.ExpiresAt); err != nil {
			return nil, 0, err
		}
		out = append(out, inv)
	}
	return out, total, rows.Err()
}

// RevokeInvite deletes a pending invite owned by the company.
func (s *Service) RevokeInvite(ctx context.Context, companyID, inviteID uuid.UUID) error {
	ct, err := s.Pool.Exec(ctx, `
		DELETE FROM invites
		WHERE id = $1 AND company_id = $2 AND accepted_at IS NULL`, inviteID, companyID)
	if err != nil {
		return err
	}
	if ct.RowsAffected() == 0 {
		return ErrInviteNotFound
	}
	return nil
}

// CompanyName returns the display name for a company.
func (s *Service) CompanyName(ctx context.Context, companyID uuid.UUID) (string, error) {
	var name string
	err := s.Pool.QueryRow(ctx, `SELECT name FROM companies WHERE id = $1`, companyID).Scan(&name)
	if errors.Is(err, pgx.ErrNoRows) {
		return "", errors.New("company not found")
	}
	return name, err
}

// UpdateMembershipRole sets an active membership role to admin or member.
func (s *Service) UpdateMembershipRole(ctx context.Context, companyID, userID uuid.UUID, role string) (Membership, error) {
	role = normalizeInviteRole(role)
	var m Membership
	err := s.Pool.QueryRow(ctx, `
		UPDATE memberships
		SET role = $3, updated_at = now()
		WHERE company_id = $1 AND user_id = $2 AND status = 'active'
		RETURNING id, company_id, user_id, role, status`,
		companyID, userID, role,
	).Scan(&m.ID, &m.CompanyID, &m.UserID, &m.Role, &m.Status)
	if errors.Is(err, pgx.ErrNoRows) {
		return Membership{}, ErrNotCompanyMember
	}
	return m, err
}

// IsPlatformAdmin reports whether the user has full platform admin privileges
// (admin/developer or legacy is_platform_admin). support_staff is excluded.
func (s *Service) IsPlatformAdmin(ctx context.Context, userID uuid.UUID) (bool, error) {
	access, err := s.GetStaffAccess(ctx, userID)
	if err != nil {
		return false, err
	}
	return access.FullAdmin, nil
}

// UpdateProfile updates the user's display name.
func (s *Service) UpdateProfile(ctx context.Context, userID uuid.UUID, name string) (User, error) {
	name = strings.TrimSpace(name)
	var n *string
	if name != "" {
		n = &name
	}
	_, err := s.Pool.Exec(ctx, `
		UPDATE users SET name = $2, updated_at = now() WHERE id = $1`, userID, n)
	if err != nil {
		return User{}, err
	}
	return s.GetUser(ctx, userID)
}

// ListUsersNeedingPassword returns active users with must_set_password (migration cutover).
func (s *Service) ListUsersNeedingPassword(ctx context.Context, limit int) ([]User, error) {
	if limit <= 0 {
		limit = 100
	}
	rows, err := s.Pool.Query(ctx, `
		SELECT id, email, name, must_set_password, is_platform_admin, staff_role, is_active
		FROM users
		WHERE must_set_password = true AND is_active = true
		ORDER BY email
		LIMIT $1`, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []User
	for rows.Next() {
		var u User
		if err := rows.Scan(&u.ID, &u.Email, &u.Name, &u.MustSetPassword, &u.IsPlatformAdmin, &u.StaffRole, &u.IsActive); err != nil {
			return nil, err
		}
		out = append(out, u)
	}
	return out, rows.Err()
}

// ReissueSetPasswordInvite expires prior pending invites and creates a durable invite for a
// must_set_password user with an active membership. Token plaintext is returned once.
func (s *Service) ReissueSetPasswordInvite(ctx context.Context, userID uuid.UUID, ttl time.Duration) (SetPasswordInvite, error) {
	if ttl <= 0 {
		ttl = 7 * 24 * time.Hour
	}
	var (
		out             SetPasswordInvite
		mustSetPassword bool
		isActive        bool
	)
	err := s.Pool.QueryRow(ctx, `
		SELECT id, email, must_set_password, is_active
		FROM users WHERE id = $1`, userID).Scan(&out.UserID, &out.Email, &mustSetPassword, &isActive)
	if errors.Is(err, pgx.ErrNoRows) {
		return SetPasswordInvite{}, ErrUserNotFound
	}
	if err != nil {
		return SetPasswordInvite{}, err
	}
	if !isActive || !mustSetPassword {
		return SetPasswordInvite{}, ErrNotEligibleSetPassword
	}
	if IsSyntheticLegacyEmail(out.Email) {
		return SetPasswordInvite{}, ErrSyntheticEmail
	}
	out.Email = strings.ToLower(strings.TrimSpace(out.Email))

	err = s.Pool.QueryRow(ctx, `
		SELECT company_id, role
		FROM memberships
		WHERE user_id = $1 AND status = 'active'
		ORDER BY created_at
		LIMIT 1`, userID).Scan(&out.CompanyID, &out.Role)
	if errors.Is(err, pgx.ErrNoRows) {
		return SetPasswordInvite{}, ErrNotEligibleSetPassword
	}
	if err != nil {
		return SetPasswordInvite{}, err
	}
	out.Role = normalizeInviteRole(out.Role)

	token, err := RandomToken(24)
	if err != nil {
		return SetPasswordInvite{}, err
	}
	out.Token = token
	out.ExpiresAt = time.Now().UTC().Add(ttl)

	// Expire prior unaccepted invites for this email+company so re-issue is safe.
	if _, err := s.Pool.Exec(ctx, `
		UPDATE invites
		SET expires_at = least(expires_at, now())
		WHERE company_id = $1 AND lower(email) = lower($2) AND accepted_at IS NULL`,
		out.CompanyID, out.Email); err != nil {
		return SetPasswordInvite{}, err
	}

	err = s.Pool.QueryRow(ctx, `
		INSERT INTO invites (company_id, email, role, token, expires_at)
		VALUES ($1, $2, $3, $4, $5)
		RETURNING id`,
		out.CompanyID, out.Email, out.Role, HashInviteToken(token), out.ExpiresAt,
	).Scan(&out.InviteID)
	if err != nil {
		return SetPasswordInvite{}, err
	}
	return out, nil
}