// accountServiceServer implements mciasv1.AccountServiceServer.
// All RPCs require admin role.
package grpcserver

import (
	"context"
	"errors"
	"fmt"

	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
	"google.golang.org/protobuf/types/known/timestamppb"

	mciasv1 "git.wntrmute.dev/kyle/mcias/gen/mcias/v1"
	"git.wntrmute.dev/kyle/mcias/internal/auth"
	"git.wntrmute.dev/kyle/mcias/internal/db"
	"git.wntrmute.dev/kyle/mcias/internal/model"
	"git.wntrmute.dev/kyle/mcias/internal/validate"
)

type accountServiceServer struct {
	mciasv1.UnimplementedAccountServiceServer
	s *Server
}

// accountToProto converts an internal Account to the proto message.
// Credential fields (PasswordHash, TOTPSecret*) are never included.
func accountToProto(a *model.Account) *mciasv1.Account {
	acc := &mciasv1.Account{
		Id:          a.UUID,
		Username:    a.Username,
		AccountType: string(a.AccountType),
		Status:      string(a.Status),
		TotpEnabled: a.TOTPRequired,
		CreatedAt:   timestamppb.New(a.CreatedAt),
		UpdatedAt:   timestamppb.New(a.UpdatedAt),
	}
	return acc
}

// ListAccounts returns all accounts. Admin only.
func (a *accountServiceServer) ListAccounts(ctx context.Context, _ *mciasv1.ListAccountsRequest) (*mciasv1.ListAccountsResponse, error) {
	if err := a.s.requireAdmin(ctx); err != nil {
		return nil, err
	}
	accounts, err := a.s.db.ListAccounts()
	if err != nil {
		return nil, status.Error(codes.Internal, "internal error")
	}
	resp := make([]*mciasv1.Account, len(accounts))
	for i, acct := range accounts {
		resp[i] = accountToProto(acct)
	}
	return &mciasv1.ListAccountsResponse{Accounts: resp}, nil
}

// CreateAccount creates a new account. Admin only.
func (a *accountServiceServer) CreateAccount(ctx context.Context, req *mciasv1.CreateAccountRequest) (*mciasv1.CreateAccountResponse, error) {
	if err := a.s.requireAdmin(ctx); err != nil {
		return nil, err
	}
	// Security (F-12): validate username length and character set.
	if err := validate.Username(req.Username); err != nil {
		return nil, status.Error(codes.InvalidArgument, err.Error())
	}
	accountType := model.AccountType(req.AccountType)
	if accountType != model.AccountTypeHuman && accountType != model.AccountTypeSystem {
		return nil, status.Error(codes.InvalidArgument, "account_type must be 'human' or 'system'")
	}

	var passwordHash string
	if accountType == model.AccountTypeHuman {
		if req.Password == "" {
			return nil, status.Error(codes.InvalidArgument, "password is required for human accounts")
		}
		// Security (F-13): enforce minimum length before hashing.
		if err := validate.Password(req.Password); err != nil {
			return nil, status.Error(codes.InvalidArgument, err.Error())
		}
		var err error
		passwordHash, err = auth.HashPassword(req.Password, auth.ArgonParams{
			Time:    a.s.cfg.Argon2.Time,
			Memory:  a.s.cfg.Argon2.Memory,
			Threads: a.s.cfg.Argon2.Threads,
		})
		if err != nil {
			return nil, status.Error(codes.Internal, "internal error")
		}
	}

	acct, err := a.s.db.CreateAccount(req.Username, accountType, passwordHash)
	if err != nil {
		return nil, status.Error(codes.AlreadyExists, "username already exists")
	}

	a.s.db.WriteAuditEvent(model.EventAccountCreated, nil, &acct.ID, peerIP(ctx), //nolint:errcheck
		fmt.Sprintf(`{"username":%q}`, acct.Username))
	return &mciasv1.CreateAccountResponse{Account: accountToProto(acct)}, nil
}

// GetAccount retrieves a single account by UUID. Admin only.
func (a *accountServiceServer) GetAccount(ctx context.Context, req *mciasv1.GetAccountRequest) (*mciasv1.GetAccountResponse, error) {
	if err := a.s.requireAdmin(ctx); err != nil {
		return nil, err
	}
	if req.Id == "" {
		return nil, status.Error(codes.InvalidArgument, "id is required")
	}
	acct, err := a.s.db.GetAccountByUUID(req.Id)
	if err != nil {
		if errors.Is(err, db.ErrNotFound) {
			return nil, status.Error(codes.NotFound, "account not found")
		}
		return nil, status.Error(codes.Internal, "internal error")
	}
	return &mciasv1.GetAccountResponse{Account: accountToProto(acct)}, nil
}

// UpdateAccount updates mutable fields. Admin only.
func (a *accountServiceServer) UpdateAccount(ctx context.Context, req *mciasv1.UpdateAccountRequest) (*mciasv1.UpdateAccountResponse, error) {
	if err := a.s.requireAdmin(ctx); err != nil {
		return nil, err
	}
	if req.Id == "" {
		return nil, status.Error(codes.InvalidArgument, "id is required")
	}
	acct, err := a.s.db.GetAccountByUUID(req.Id)
	if err != nil {
		if errors.Is(err, db.ErrNotFound) {
			return nil, status.Error(codes.NotFound, "account not found")
		}
		return nil, status.Error(codes.Internal, "internal error")
	}

	if req.Status != "" {
		newStatus := model.AccountStatus(req.Status)
		if newStatus != model.AccountStatusActive && newStatus != model.AccountStatusInactive {
			return nil, status.Error(codes.InvalidArgument, "status must be 'active' or 'inactive'")
		}
		if err := a.s.db.UpdateAccountStatus(acct.ID, newStatus); err != nil {
			return nil, status.Error(codes.Internal, "internal error")
		}
	}

	a.s.db.WriteAuditEvent(model.EventAccountUpdated, nil, &acct.ID, peerIP(ctx), "") //nolint:errcheck
	return &mciasv1.UpdateAccountResponse{}, nil
}

// DeleteAccount soft-deletes an account and revokes its tokens. Admin only.
func (a *accountServiceServer) DeleteAccount(ctx context.Context, req *mciasv1.DeleteAccountRequest) (*mciasv1.DeleteAccountResponse, error) {
	if err := a.s.requireAdmin(ctx); err != nil {
		return nil, err
	}
	if req.Id == "" {
		return nil, status.Error(codes.InvalidArgument, "id is required")
	}
	acct, err := a.s.db.GetAccountByUUID(req.Id)
	if err != nil {
		if errors.Is(err, db.ErrNotFound) {
			return nil, status.Error(codes.NotFound, "account not found")
		}
		return nil, status.Error(codes.Internal, "internal error")
	}
	if err := a.s.db.UpdateAccountStatus(acct.ID, model.AccountStatusDeleted); err != nil {
		return nil, status.Error(codes.Internal, "internal error")
	}
	if err := a.s.db.RevokeAllUserTokens(acct.ID, "account deleted"); err != nil {
		a.s.logger.Error("revoke tokens on delete", "error", err, "account_id", acct.ID)
	}
	a.s.db.WriteAuditEvent(model.EventAccountDeleted, nil, &acct.ID, peerIP(ctx), "") //nolint:errcheck
	return &mciasv1.DeleteAccountResponse{}, nil
}

// GetRoles returns the roles for an account. Admin only.
func (a *accountServiceServer) GetRoles(ctx context.Context, req *mciasv1.GetRolesRequest) (*mciasv1.GetRolesResponse, error) {
	if err := a.s.requireAdmin(ctx); err != nil {
		return nil, err
	}
	if req.Id == "" {
		return nil, status.Error(codes.InvalidArgument, "id is required")
	}
	acct, err := a.s.db.GetAccountByUUID(req.Id)
	if err != nil {
		if errors.Is(err, db.ErrNotFound) {
			return nil, status.Error(codes.NotFound, "account not found")
		}
		return nil, status.Error(codes.Internal, "internal error")
	}
	roles, err := a.s.db.GetRoles(acct.ID)
	if err != nil {
		return nil, status.Error(codes.Internal, "internal error")
	}
	if roles == nil {
		roles = []string{}
	}
	return &mciasv1.GetRolesResponse{Roles: roles}, nil
}

// SetRoles replaces the role set for an account. Admin only.
func (a *accountServiceServer) SetRoles(ctx context.Context, req *mciasv1.SetRolesRequest) (*mciasv1.SetRolesResponse, error) {
	if err := a.s.requireAdmin(ctx); err != nil {
		return nil, err
	}
	if req.Id == "" {
		return nil, status.Error(codes.InvalidArgument, "id is required")
	}
	acct, err := a.s.db.GetAccountByUUID(req.Id)
	if err != nil {
		if errors.Is(err, db.ErrNotFound) {
			return nil, status.Error(codes.NotFound, "account not found")
		}
		return nil, status.Error(codes.Internal, "internal error")
	}

	actorClaims := claimsFromContext(ctx)
	var grantedBy *int64
	if actorClaims != nil {
		if actor, err := a.s.db.GetAccountByUUID(actorClaims.Subject); err == nil {
			grantedBy = &actor.ID
		}
	}

	if err := a.s.db.SetRoles(acct.ID, req.Roles, grantedBy); err != nil {
		return nil, status.Error(codes.Internal, "internal error")
	}
	a.s.db.WriteAuditEvent(model.EventRoleGranted, grantedBy, &acct.ID, peerIP(ctx), //nolint:errcheck
		fmt.Sprintf(`{"roles":%v}`, req.Roles))
	return &mciasv1.SetRolesResponse{}, nil
}