package store

import (
	"context"
	"errors"
	"fmt"

	"github.com/jackc/pgx/v5"
	"github.com/loyaly/behavision-server/internal/api"
)

// Adding people to a company, and taking them out again.
//
// Registration here is by invitation only. `handlers_team.go` carries the
// product argument; what matters at this layer is that every statement is
// scoped by the CALLER'S client id, taken from their session, so a manager
// cannot invite somebody into, list, or remove a member of a company that is
// not theirs by guessing a uuid.

// CreateInvitation writes a pending invitation for one company.
//
// The client id is not trusted from a caller anywhere above this, but it is
// still joined against `clients` here rather than inserted blind: a foreign-key
// violation surfaces as an opaque 500, and a row that names a company which has
// since been deleted is worse than a clean refusal.
func (s *Store) CreateInvitation(ctx context.Context, in api.NewInvitation) (api.Invitation, error) {
	var out api.Invitation
	err := s.pool.QueryRow(ctx, `
		INSERT INTO invitations (client_id, email, full_name, role, code_hash,
		                         invited_by, expires_at)
		SELECT c.id, $2, $3, $4, $5, $6::uuid, $7
		  FROM clients c
		 WHERE c.id = $1::uuid
		RETURNING id::text, email, full_name, role,
		          to_char(expires_at AT TIME ZONE 'UTC', 'YYYY-MM-DD"T"HH24:MI:SS"Z"'),
		          to_char(created_at AT TIME ZONE 'UTC', 'YYYY-MM-DD"T"HH24:MI:SS"Z"')`,
		in.ClientID, in.Email, in.FullName, in.Role, in.CodeHash,
		nullUUID(in.InvitedBy), in.ExpiresAt,
	).Scan(&out.ID, &out.Email, &out.FullName, &out.Role,
		&out.ExpiresAt, &out.CreatedAt)
	if errors.Is(err, pgx.ErrNoRows) {
		return api.Invitation{}, errors.New("no such company")
	}
	if err != nil {
		return api.Invitation{}, fmt.Errorf("create invitation: %w", err)
	}
	return out, nil
}

// PendingInvitations lists the invitations that have been sent and not yet
// taken up. Spent and revoked rows are history and are deliberately not here:
// the question this list answers is "who is still waiting to join".
func (s *Store) PendingInvitations(ctx context.Context, clientID string) ([]api.Invitation, error) {
	rows, err := s.pool.Query(ctx, `
		SELECT i.id::text, i.email, i.full_name, i.role,
		       COALESCE(u.full_name, u.email, ''),
		       to_char(i.expires_at AT TIME ZONE 'UTC', 'YYYY-MM-DD"T"HH24:MI:SS"Z"'),
		       to_char(i.created_at AT TIME ZONE 'UTC', 'YYYY-MM-DD"T"HH24:MI:SS"Z"')
		  FROM invitations i
		  LEFT JOIN app_users u ON u.id = i.invited_by
		 WHERE i.client_id = $1::uuid
		   AND i.used_at IS NULL AND i.revoked_at IS NULL
		   AND i.expires_at > now()
		 ORDER BY i.created_at DESC`, clientID)
	if err != nil {
		return nil, fmt.Errorf("list invitations: %w", err)
	}
	defer rows.Close()

	var out []api.Invitation
	for rows.Next() {
		var v api.Invitation
		if err := rows.Scan(&v.ID, &v.Email, &v.FullName, &v.Role,
			&v.InvitedBy, &v.ExpiresAt, &v.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, v)
	}
	return out, rows.Err()
}

// RevokeInvitation withdraws one before it is used.
//
// Scoped by client in the UPDATE, and it refuses an already-spent invitation
// rather than silently doing nothing: "I revoked it" and "somebody had already
// joined with it" need opposite follow-up actions from whoever asked.
func (s *Store) RevokeInvitation(ctx context.Context, clientID, id string) error {
	tag, err := s.pool.Exec(ctx, `
		UPDATE invitations SET revoked_at = now()
		 WHERE id = $2::uuid AND client_id = $1::uuid
		   AND used_at IS NULL AND revoked_at IS NULL`, clientID, id)
	if err != nil {
		return fmt.Errorf("revoke invitation: %w", err)
	}
	if tag.RowsAffected() == 0 {
		return errors.New("no such pending invitation")
	}
	return nil
}

// InvitationByCode is the unauthenticated preview: what a holder may learn
// about a code they already have.
//
// Every way of not being valid returns the same error, so this cannot be used
// to tell an expired code from an invented one.
func (s *Store) InvitationByCode(ctx context.Context, hash []byte) (api.InvitationPreview, error) {
	var out api.InvitationPreview
	err := s.pool.QueryRow(ctx, `
		SELECT c.name, i.email, i.full_name, i.role
		  FROM invitations i
		  JOIN clients c ON c.id = i.client_id
		 WHERE i.code_hash = $1
		   AND i.used_at IS NULL AND i.revoked_at IS NULL
		   AND i.expires_at > now()`, hash,
	).Scan(&out.Client, &out.Email, &out.FullName, &out.Role)
	if err != nil {
		return api.InvitationPreview{}, errors.New("that invitation is not valid")
	}
	return out, nil
}

// RedeemInvitation turns a code into an account, in ONE transaction.
//
// Two properties, and both were learned elsewhere in this system:
//
//   - Single use is enforced BY the update. `used_at IS NULL` and the write are
//     one statement, so two people racing on one invitation cannot both win.
//     Check-then-update would be exactly that race, and the loser would get a
//     second account rather than an error.
//   - The account and the redemption commit together. A spent invitation with
//     no user behind it is an invitation nobody can use and nobody can see is
//     broken; a user with the invitation still open is a second account waiting
//     to be created by anyone who was forwarded the code.
//
// The email and the role come from the ROW, never from the request. A code
// passed on to a colleague must not become an account for them, and a staff
// invitation must not be redeemed as an owner.
func (s *Store) RedeemInvitation(ctx context.Context, hash []byte,
	fullName, passwordHash string) (api.UserRecord, error) {

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return api.UserRecord{}, err
	}
	defer tx.Rollback(ctx) //nolint:errcheck // no-op once committed

	var clientID, email, role, invitedName string
	err = tx.QueryRow(ctx, `
		UPDATE invitations SET used_at = now()
		 WHERE code_hash = $1
		   AND used_at IS NULL AND revoked_at IS NULL AND expires_at > now()
		RETURNING client_id::text, email, role, full_name`, hash,
	).Scan(&clientID, &email, &role, &invitedName)
	if errors.Is(err, pgx.ErrNoRows) {
		return api.UserRecord{}, errors.New("that invitation is not valid")
	}
	if err != nil {
		return api.UserRecord{}, fmt.Errorf("redeem invitation: %w", err)
	}

	if fullName == "" {
		// The inviter may have typed a name; use it rather than leaving a
		// blank row that every screen then renders as an email address.
		fullName = invitedName
	}

	var rec api.UserRecord
	err = tx.QueryRow(ctx, `
		INSERT INTO app_users (client_id, email, password_hash, full_name, role)
		VALUES ($1::uuid, $2, $3, $4, $5)
		RETURNING id::text, email, full_name, role`,
		clientID, email, passwordHash, fullName, role,
	).Scan(&rec.ID, &rec.Email, &rec.FullName, &rec.Role)
	if err != nil {
		return api.UserRecord{}, fmt.Errorf("create user: %w", err)
	}

	var clientName string
	if err := tx.QueryRow(ctx, `SELECT name FROM clients WHERE id = $1::uuid`,
		clientID).Scan(&clientName); err != nil {
		return api.UserRecord{}, err
	}

	// Recorded against the new account, not the inviter: this is the moment a
	// person gained access, and the row should name who did.
	rec.ClientID, rec.ClientName, rec.Active, rec.Found = clientID, clientName, true, true

	if err := tx.Commit(ctx); err != nil {
		return api.UserRecord{}, err
	}
	return rec, nil
}

// Team lists the people in one company.
func (s *Store) Team(ctx context.Context, clientID string) ([]api.TeamMember, error) {
	rows, err := s.pool.Query(ctx, `
		SELECT id::text, email, full_name, role, active,
		       COALESCE(to_char(last_login_at AT TIME ZONE 'UTC',
		                        'YYYY-MM-DD"T"HH24:MI:SS"Z"'), ''),
		       to_char(created_at AT TIME ZONE 'UTC', 'YYYY-MM-DD"T"HH24:MI:SS"Z"')
		  FROM app_users
		 WHERE client_id = $1::uuid
		 ORDER BY active DESC, full_name, email`, clientID)
	if err != nil {
		return nil, fmt.Errorf("list team: %w", err)
	}
	defer rows.Close()

	var out []api.TeamMember
	for rows.Next() {
		var m api.TeamMember
		if err := rows.Scan(&m.ID, &m.Email, &m.FullName, &m.Role, &m.Active,
			&m.LastLoginAt, &m.CreatedAt); err != nil {
			return nil, err
		}
		out = append(out, m)
	}
	return out, rows.Err()
}

// UpdateTeamMember changes a role, or deactivates somebody who has left.
//
// Deactivating REVOKES their sessions in the same transaction. Leaving them
// live would mean "remove their access" removed it in twelve hours' time,
// whenever their access token happened to expire - which is not what anybody
// pressing that button believes they have just done, and is precisely the case
// an opaque-token session table exists to handle.
func (s *Store) UpdateTeamMember(ctx context.Context, clientID, userID string,
	up api.TeamUpdate) (api.TeamMember, error) {

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return api.TeamMember{}, err
	}
	defer tx.Rollback(ctx) //nolint:errcheck // no-op once committed

	var m api.TeamMember
	err = tx.QueryRow(ctx, `
		UPDATE app_users
		   SET role   = COALESCE($3, role),
		       active = COALESCE($4, active)
		 WHERE id = $2::uuid AND client_id = $1::uuid
		RETURNING id::text, email, full_name, role, active,
		          COALESCE(to_char(last_login_at AT TIME ZONE 'UTC',
		                           'YYYY-MM-DD"T"HH24:MI:SS"Z"'), ''),
		          to_char(created_at AT TIME ZONE 'UTC', 'YYYY-MM-DD"T"HH24:MI:SS"Z"')`,
		clientID, userID, up.Role, up.Active,
	).Scan(&m.ID, &m.Email, &m.FullName, &m.Role, &m.Active,
		&m.LastLoginAt, &m.CreatedAt)
	if errors.Is(err, pgx.ErrNoRows) {
		return api.TeamMember{}, errors.New("no such team member")
	}
	if err != nil {
		return api.TeamMember{}, fmt.Errorf("update team member: %w", err)
	}

	if up.Active != nil && !*up.Active {
		if _, err := tx.Exec(ctx, `
			UPDATE sessions SET revoked_at = now()
			 WHERE user_id = $1::uuid AND revoked_at IS NULL`, userID); err != nil {
			return api.TeamMember{}, fmt.Errorf("revoke sessions: %w", err)
		}
	}
	if err := tx.Commit(ctx); err != nil {
		return api.TeamMember{}, err
	}
	return m, nil
}

// OwnerCount counts the active owners of a company.
//
// Used to refuse the change that locks a company out of its own account: the
// last owner may not demote or deactivate themselves. There is no support path
// back from that except a shell on the server, which is the thing this whole
// surface exists to stop needing.
func (s *Store) OwnerCount(ctx context.Context, clientID string) (int, error) {
	var n int
	err := s.pool.QueryRow(ctx, `
		SELECT count(*) FROM app_users
		 WHERE client_id = $1::uuid AND role = 'owner' AND active`, clientID).Scan(&n)
	return n, err
}

// ============================================================== sessions ====

// UserSessions lists one person's live sessions, newest first.
func (s *Store) UserSessions(ctx context.Context, userID string) ([]api.DeviceSession, error) {
	rows, err := s.pool.Query(ctx, `
		SELECT id::text, device,
		       to_char(created_at AT TIME ZONE 'UTC', 'YYYY-MM-DD"T"HH24:MI:SS"Z"'),
		       COALESCE(to_char(last_used_at AT TIME ZONE 'UTC',
		                        'YYYY-MM-DD"T"HH24:MI:SS"Z"'), ''),
		       to_char(refresh_expires_at AT TIME ZONE 'UTC', 'YYYY-MM-DD"T"HH24:MI:SS"Z"')
		  FROM sessions
		 WHERE user_id = $1::uuid AND revoked_at IS NULL
		   AND refresh_expires_at > now()
		 ORDER BY COALESCE(last_used_at, created_at) DESC`, userID)
	if err != nil {
		return nil, fmt.Errorf("list sessions: %w", err)
	}
	defer rows.Close()

	var out []api.DeviceSession
	for rows.Next() {
		var d api.DeviceSession
		if err := rows.Scan(&d.ID, &d.Device, &d.CreatedAt,
			&d.LastUsedAt, &d.ExpiresAt); err != nil {
			return nil, err
		}
		out = append(out, d)
	}
	return out, rows.Err()
}

// RevokeUserSession signs one device out.
//
// Scoped by user_id in the UPDATE, so a session id - which is not a secret and
// travels in a list - cannot be used to sign somebody else out.
func (s *Store) RevokeUserSession(ctx context.Context, userID, sessionID string) error {
	tag, err := s.pool.Exec(ctx, `
		UPDATE sessions SET revoked_at = now()
		 WHERE id = $2::uuid AND user_id = $1::uuid AND revoked_at IS NULL`,
		userID, sessionID)
	if err != nil {
		return fmt.Errorf("revoke session: %w", err)
	}
	if tag.RowsAffected() == 0 {
		return errors.New("no such session")
	}
	return nil
}

// RevokeOtherSessions is the "sign out everywhere else" button.
//
// It keeps the caller's own session deliberately: somebody who has just lost a
// phone should not also be signed out of the device they are holding, which
// would leave them re-authenticating in the middle of an emergency.
func (s *Store) RevokeOtherSessions(ctx context.Context, userID, keepSessionID string) (int, error) {
	tag, err := s.pool.Exec(ctx, `
		UPDATE sessions SET revoked_at = now()
		 WHERE user_id = $1::uuid AND id <> $2::uuid AND revoked_at IS NULL`,
		userID, keepSessionID)
	if err != nil {
		return 0, fmt.Errorf("revoke sessions: %w", err)
	}
	return int(tag.RowsAffected()), nil
}

// CreateMember inserts an active account into a tenant.
//
// The email uniqueness constraint is global (migration 007), and a clash here
// is an ordinary typing mistake - somebody already has that address - so it
// surfaces as a conflict the manager can act on, not a 500.
func (s *Store) CreateMember(ctx context.Context, clientID string,
	in api.NewMemberInput, hash string) (api.TeamMember, error) {

	var m api.TeamMember
	err := s.pool.QueryRow(ctx, `
		INSERT INTO app_users (client_id, email, password_hash, full_name, role)
		VALUES ($1::uuid, $2, $3, $4, $5)
		RETURNING id::text, email, full_name, role, active, '',
		          to_char(created_at AT TIME ZONE 'UTC', 'YYYY-MM-DD"T"HH24:MI:SS"Z"')`,
		clientID, in.Email, hash, in.FullName, in.Role,
	).Scan(&m.ID, &m.Email, &m.FullName, &m.Role, &m.Active,
		&m.LastLoginAt, &m.CreatedAt)
	if err != nil {
		return api.TeamMember{}, fmt.Errorf("create member: %w", err)
	}
	return m, nil
}

// ResetMemberPassword replaces a member's password and signs them out
// everywhere, in one transaction.
//
// The two go together because of why a manager resets a password at all: the
// salesperson forgot it, or lost the phone it was saved on. In the second case
// the old sessions are the problem, and a reset that left them valid would
// look complete while changing nothing that mattered. Scoped to the caller's
// tenant in the UPDATE itself, so a user id from another company matches no
// row rather than being reset.
func (s *Store) ResetMemberPassword(ctx context.Context, clientID, userID,
	hash string) (api.TeamMember, error) {

	tx, err := s.pool.Begin(ctx)
	if err != nil {
		return api.TeamMember{}, err
	}
	defer tx.Rollback(ctx) //nolint:errcheck // no-op once committed

	var m api.TeamMember
	err = tx.QueryRow(ctx, `
		UPDATE app_users SET password_hash = $3
		 WHERE id = $2::uuid AND client_id = $1::uuid
		RETURNING id::text, email, full_name, role, active,
		          COALESCE(to_char(last_login_at AT TIME ZONE 'UTC',
		                           'YYYY-MM-DD"T"HH24:MI:SS"Z"'), ''),
		          to_char(created_at AT TIME ZONE 'UTC', 'YYYY-MM-DD"T"HH24:MI:SS"Z"')`,
		clientID, userID, hash,
	).Scan(&m.ID, &m.Email, &m.FullName, &m.Role, &m.Active,
		&m.LastLoginAt, &m.CreatedAt)
	if errors.Is(err, pgx.ErrNoRows) {
		return api.TeamMember{}, errors.New("no such team member")
	}
	if err != nil {
		return api.TeamMember{}, fmt.Errorf("reset password: %w", err)
	}
	if _, err := tx.Exec(ctx, `
		UPDATE sessions SET revoked_at = now()
		 WHERE user_id = $1::uuid AND revoked_at IS NULL`, userID); err != nil {
		return api.TeamMember{}, fmt.Errorf("revoke sessions: %w", err)
	}
	if err := tx.Commit(ctx); err != nil {
		return api.TeamMember{}, err
	}
	return m, nil
}