package authtoken

import (
	"context"
	"errors"
	"fmt"
	"time"

	"github.com/golang/protobuf/ptypes"
	wrapping "github.com/hashicorp/go-kms-wrapping"
	"github.com/hashicorp/watchtower/internal/db/timestamp"
	"github.com/hashicorp/watchtower/internal/iam"
	iamStore "github.com/hashicorp/watchtower/internal/iam/store"

	"github.com/hashicorp/watchtower/internal/authtoken/store"
	"github.com/hashicorp/watchtower/internal/db"
	"github.com/hashicorp/watchtower/internal/oplog"
)

// TODO (ICU-406): Make these fields configurable.
var (
	lastAccessedUpdateDuration = 10 * time.Minute
	maxStaleness               = 24 * time.Hour
	maxTokenDuration           = 7 * 24 * time.Hour
)

// A Repository stores and retrieves the persistent types in the authtoken
// package. It is not safe to use a repository concurrently.
type Repository struct {
	reader  db.Reader
	writer  db.Writer
	wrapper wrapping.Wrapper
}

// NewRepository creates a new Repository. The returned repository is not safe for concurrent go
// routines to access it.
func NewRepository(r db.Reader, w db.Writer, wrapper wrapping.Wrapper) (*Repository, error) {
	switch {
	case r == nil:
		return nil, fmt.Errorf("db.Reader: auth token: %w", db.ErrNilParameter)
	case w == nil:
		return nil, fmt.Errorf("db.Writer: auth token: %w", db.ErrNilParameter)
	case wrapper == nil:
		return nil, fmt.Errorf("wrapping.Wrapper: auth token: %w", db.ErrNilParameter)
	}

	return &Repository{
		reader:  r,
		writer:  w,
		wrapper: wrapper,
	}, nil
}

// CreateAuthToken inserts an Auth Token into the repository and returns a new Auth Token.  The returned auth token
// contains the auth token value. The provided IAM User ID must be associated to the provided auth account id
// or an error will be returned. All options are ignored.
func (r *Repository) CreateAuthToken(ctx context.Context, withIamUserId, withAuthAccountId string, opt ...Option) (*AuthToken, error) {
	if withIamUserId == "" {
		return nil, fmt.Errorf("create: auth token: no user id: %w", db.ErrInvalidParameter)
	}
	if withAuthAccountId == "" {
		return nil, fmt.Errorf("create: auth token: no auth account id: %w", db.ErrInvalidParameter)
	}

	at := allocAuthToken()
	at.AuthAccountId = withAuthAccountId

	id, err := newAuthTokenId()
	if err != nil {
		return nil, fmt.Errorf("create: auth token id: %w", err)
	}
	at.PublicId = id

	token, err := newAuthToken()
	if err != nil {
		return nil, fmt.Errorf("create: auth token value: %w", err)
	}
	at.Token = token

	// TODO: Allow the caller to specify something different than the default duration.
	expiration, err := ptypes.TimestampProto(time.Now().Add(maxTokenDuration))
	if err != nil {
		return nil, err
	}
	at.ExpirationTime = &timestamp.Timestamp{Timestamp: expiration}

	var newAuthToken *AuthToken
	_, err = r.writer.DoTx(
		ctx,
		db.StdRetryCnt,
		db.ExpBackoff{},
		func(read db.Reader, w db.Writer) error {
			// TODO: Remove this and either rely on either Alloc or a method exposed by the auth repo.
			acct := &iam.AuthAccount{AuthAccount: &iamStore.AuthAccount{PublicId: withAuthAccountId}}
			if err := read.LookupByPublicId(ctx, acct); err != nil {
				return fmt.Errorf("create: auth token: auth account lookup: %w", err)
			}
			if acct.GetIamUserId() != withIamUserId {
				return fmt.Errorf("create: auth token: auth account %q mismatch with iam user %q", withAuthAccountId, withIamUserId)
			}
			at.ScopeId = acct.GetScopeId()
			at.AuthMethodId = acct.GetAuthMethodId()
			at.IamUserId = acct.GetIamUserId()

			metadata := newAuthTokenMetadata(at, oplog.OpType_OP_TYPE_CREATE)

			newAuthToken = at.clone()
			if err := newAuthToken.encrypt(ctx, r.wrapper); err != nil {
				return err
			}
			if err := w.Create(ctx, newAuthToken, db.WithOplog(r.wrapper, metadata)); err != nil {
				return err
			}
			newAuthToken.CtToken = nil

			return nil
		},
	)

	if err != nil {
		return nil, fmt.Errorf("create: auth token: %v: %w", at, err)
	}
	return newAuthToken, nil
}

// LookupAuthToken returns the AuthToken for the provided id. Returns nil, nil if no AuthToken is found for id.
// For security reasons, the actual token is not included in the returned AuthToken.
// All exported options are ignored.
func (r *Repository) LookupAuthToken(ctx context.Context, id string, opt ...Option) (*AuthToken, error) {
	if id == "" {
		return nil, fmt.Errorf("lookup: auth token: missing public id: %w", db.ErrInvalidParameter)
	}
	opts := getOpts(opt...)

	at := allocAuthToken()
	at.PublicId = id
	// Aggregate the fields across auth token and auth accounts by using this view instead of issuing 2 db lookups.
	at.SetTableName("auth_token_account")
	if err := r.reader.LookupByPublicId(ctx, at); err != nil {
		if errors.Is(err, db.ErrRecordNotFound) {
			return nil, nil
		}
		return nil, fmt.Errorf("auth token: lookup: %w", err)
	}
	if opts.withTokenValue {
		if err := at.decrypt(ctx, r.wrapper); err != nil {
			return nil, fmt.Errorf("lookup: auth token: cannot decrypt auth token value: %w", err)
		}
	}

	at.CtToken = nil
	return at, nil
}

// ValidateToken returns a token from storage if the auth token with the provided id and token exists.  The
// approximate last accessed time may be updated depending on how long it has been since the last time the token
// was validated.  If a token is returned it is guaranteed to be valid. For security reasons, the actual token
// value is not included in the returned AuthToken. If no valid auth token is found nil, nil is returned.
// All options are ignored.
//
// NOTE: Do not log or add the token string to any errors to avoid leaking it as it is a secret.
func (r *Repository) ValidateToken(ctx context.Context, id, token string, opt ...Option) (*AuthToken, error) {
	if token == "" {
		return nil, fmt.Errorf("validate token: auth token: missing token: %w", db.ErrInvalidParameter)
	}
	if id == "" {
		return nil, fmt.Errorf("validate token: auth token: missing public id: %w", db.ErrInvalidParameter)
	}

	retAT, err := r.LookupAuthToken(ctx, id, withTokenValue())
	if err != nil {
		retAT = nil
		if errors.Is(err, db.ErrRecordNotFound) {
			return nil, nil
		}
		return nil, fmt.Errorf("validate token: %w", err)
	}
	if retAT == nil {
		return nil, nil
	}

	// If the token is too old or stale invalidate it and return nothing.
	exp, err := ptypes.Timestamp(retAT.GetExpirationTime().GetTimestamp())
	if err != nil {
		return nil, fmt.Errorf("validate token: expiration time : %w", err)
	}
	lastAccessed, err := ptypes.Timestamp(retAT.GetApproximateLastAccessTime().GetTimestamp())
	if err != nil {
		return nil, fmt.Errorf("validate token: last accessed time : %w", err)
	}

	now := time.Now()
	sinceLastAccessed := now.Sub(lastAccessed)
	if now.After(exp) || sinceLastAccessed > maxStaleness {
		// If the token has expired or has become too stale, delete it from the DB.
		_, err = r.writer.DoTx(
			ctx,
			db.StdRetryCnt,
			db.ExpBackoff{},
			func(_ db.Reader, w db.Writer) error {
				metadata := newAuthTokenMetadata(retAT, oplog.OpType_OP_TYPE_DELETE)
				delAt := retAT.clone()
				if _, err := w.Delete(ctx, delAt, db.WithOplog(r.wrapper, metadata)); err != nil {
					return fmt.Errorf("validate token: delete auth token: %w", err)
				}
				retAT = nil
				return nil
			})
		return nil, nil
	}

	if retAT.GetToken() != token {
		return nil, nil
	}
	// retAT.Token set to empty string so the value is not returned as described in the methods' doc.
	retAT.Token = ""

	if sinceLastAccessed >= lastAccessedUpdateDuration {
		// To save the db from being updated too frequently, we only update the
		// LastAccessTime if it hasn't been updated within lastAccessedUpdateDuration.
		// TODO: Make this duration configurable.
		_, err = r.writer.DoTx(
			ctx,
			db.StdRetryCnt,
			db.ExpBackoff{},
			func(_ db.Reader, w db.Writer) error {
				// Setting the ApproximateLastAccessTime to null through using the null mask allows a defined db's
				// trigger to set ApproximateLastAccessTime to the commit timestamp.
				at := retAT.clone()
				metadata := newAuthTokenMetadata(retAT, oplog.OpType_OP_TYPE_UPDATE)
				rowsUpdated, err := w.Update(
					ctx,
					at,
					nil,
					[]string{"ApproximateLastAccessTime"},
					db.WithOplog(r.wrapper, metadata),
				)
				if err == nil && rowsUpdated > 1 {
					return db.ErrMultipleRecords
				}
				return err
			},
		)
	}

	if err != nil {
		return nil, fmt.Errorf("validate token: auth token: %s: %w", id, err)
	}
	return retAT, nil
}

// TODO(ICU-344): Add ListAuthTokens

// DeleteAuthToken deletes the token with the provided id from the repository returning a count of the
// number of records deleted.  All options are ignored.
func (r *Repository) DeleteAuthToken(ctx context.Context, id string, opt ...Option) (int, error) {
	if id == "" {
		return db.NoRowsAffected, fmt.Errorf("delete: auth token: missing public id: %w", db.ErrInvalidParameter)
	}

	at, err := r.LookupAuthToken(ctx, id)
	if err != nil {
		if errors.Is(err, db.ErrRecordNotFound) {
			return db.NoRowsAffected, nil
		}
		return db.NoRowsAffected, fmt.Errorf("delete: auth token: lookup %w", err)
	}
	if at == nil {
		return db.NoRowsAffected, nil
	}

	var rowsDeleted int
	_, err = r.writer.DoTx(
		ctx,
		db.StdRetryCnt,
		db.ExpBackoff{},
		func(_ db.Reader, w db.Writer) error {
			metadata := newAuthTokenMetadata(at, oplog.OpType_OP_TYPE_DELETE)

			deleteAT := at.clone()
			rowsDeleted, err = w.Delete(ctx, deleteAT, db.WithOplog(r.wrapper, metadata))
			if err == nil && rowsDeleted > 1 {
				return db.ErrMultipleRecords
			}
			return err
		},
	)

	if err != nil {
		return db.NoRowsAffected, fmt.Errorf("delete: auth token: %s: %w", id, err)
	}

	return rowsDeleted, nil
}

func allocAuthToken() *AuthToken {
	fresh := &AuthToken{
		AuthToken: &store.AuthToken{},
	}
	return fresh
}

func newAuthTokenMetadata(at *AuthToken, op oplog.OpType) oplog.Metadata {
	metadata := oplog.Metadata{
		"scope-id":           []string{at.GetScopeId()},
		"resource-public-id": []string{at.GetPublicId()},
		"resource-type":      []string{"auth token"},
		"op-type":            []string{op.String()},
	}
	return metadata
}