// Copyright 2023 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

package v1_20

import (
	"fmt"
	"strings"

	"gitea.dev/models/db"
	"gitea.dev/modules/log"
)

// unknownAccessTokenScope represents the scope for an access token that isn't
// known be an old token or a new token.
type unknownAccessTokenScope string

// AccessTokenScope represents the scope for an access token.
type AccessTokenScope string

// for all categories, write implies read
const (
	AccessTokenScopeAll        AccessTokenScope = "all"
	AccessTokenScopePublicOnly AccessTokenScope = "public-only" // limited to public orgs/repos

	AccessTokenScopeReadActivityPub  AccessTokenScope = "read:activitypub"
	AccessTokenScopeWriteActivityPub AccessTokenScope = "write:activitypub"

	AccessTokenScopeReadAdmin  AccessTokenScope = "read:admin"
	AccessTokenScopeWriteAdmin AccessTokenScope = "write:admin"

	AccessTokenScopeReadMisc  AccessTokenScope = "read:misc"
	AccessTokenScopeWriteMisc AccessTokenScope = "write:misc"

	AccessTokenScopeReadNotification  AccessTokenScope = "read:notification"
	AccessTokenScopeWriteNotification AccessTokenScope = "write:notification"

	AccessTokenScopeReadOrganization  AccessTokenScope = "read:organization"
	AccessTokenScopeWriteOrganization AccessTokenScope = "write:organization"

	AccessTokenScopeReadPackage  AccessTokenScope = "read:package"
	AccessTokenScopeWritePackage AccessTokenScope = "write:package"

	AccessTokenScopeReadIssue  AccessTokenScope = "read:issue"
	AccessTokenScopeWriteIssue AccessTokenScope = "write:issue"

	AccessTokenScopeReadRepository  AccessTokenScope = "read:repository"
	AccessTokenScopeWriteRepository AccessTokenScope = "write:repository"

	AccessTokenScopeReadUser  AccessTokenScope = "read:user"
	AccessTokenScopeWriteUser AccessTokenScope = "write:user"
)

// accessTokenScopeBitmap represents a bitmap of access token scopes.
type accessTokenScopeBitmap uint64

// Bitmap of each scope, including the child scopes.
const (
	// AccessTokenScopeAllBits is the bitmap of all access token scopes
	accessTokenScopeAllBits accessTokenScopeBitmap = accessTokenScopeWriteActivityPubBits |
		accessTokenScopeWriteAdminBits | accessTokenScopeWriteMiscBits | accessTokenScopeWriteNotificationBits |
		accessTokenScopeWriteOrganizationBits | accessTokenScopeWritePackageBits | accessTokenScopeWriteIssueBits |
		accessTokenScopeWriteRepositoryBits | accessTokenScopeWriteUserBits

	accessTokenScopePublicOnlyBits accessTokenScopeBitmap = 1 << iota

	accessTokenScopeReadActivityPubBits  accessTokenScopeBitmap = 1 << iota
	accessTokenScopeWriteActivityPubBits accessTokenScopeBitmap = 1<<iota | accessTokenScopeReadActivityPubBits

	accessTokenScopeReadAdminBits  accessTokenScopeBitmap = 1 << iota
	accessTokenScopeWriteAdminBits accessTokenScopeBitmap = 1<<iota | accessTokenScopeReadAdminBits

	accessTokenScopeReadMiscBits  accessTokenScopeBitmap = 1 << iota
	accessTokenScopeWriteMiscBits accessTokenScopeBitmap = 1<<iota | accessTokenScopeReadMiscBits

	accessTokenScopeReadNotificationBits  accessTokenScopeBitmap = 1 << iota
	accessTokenScopeWriteNotificationBits accessTokenScopeBitmap = 1<<iota | accessTokenScopeReadNotificationBits

	accessTokenScopeReadOrganizationBits  accessTokenScopeBitmap = 1 << iota
	accessTokenScopeWriteOrganizationBits accessTokenScopeBitmap = 1<<iota | accessTokenScopeReadOrganizationBits

	accessTokenScopeReadPackageBits  accessTokenScopeBitmap = 1 << iota
	accessTokenScopeWritePackageBits accessTokenScopeBitmap = 1<<iota | accessTokenScopeReadPackageBits

	accessTokenScopeReadIssueBits  accessTokenScopeBitmap = 1 << iota
	accessTokenScopeWriteIssueBits accessTokenScopeBitmap = 1<<iota | accessTokenScopeReadIssueBits

	accessTokenScopeReadRepositoryBits  accessTokenScopeBitmap = 1 << iota
	accessTokenScopeWriteRepositoryBits accessTokenScopeBitmap = 1<<iota | accessTokenScopeReadRepositoryBits

	accessTokenScopeReadUserBits  accessTokenScopeBitmap = 1 << iota
	accessTokenScopeWriteUserBits accessTokenScopeBitmap = 1<<iota | accessTokenScopeReadUserBits

	// The current implementation only supports up to 64 token scopes.
	// If we need to support > 64 scopes,
	// refactoring the whole implementation in this file (and only this file) is needed.
)

// allAccessTokenScopes contains all access token scopes.
// The order is important: parent scope must precede child scopes.
var allAccessTokenScopes = []AccessTokenScope{
	AccessTokenScopePublicOnly,
	AccessTokenScopeWriteActivityPub, AccessTokenScopeReadActivityPub,
	AccessTokenScopeWriteAdmin, AccessTokenScopeReadAdmin,
	AccessTokenScopeWriteMisc, AccessTokenScopeReadMisc,
	AccessTokenScopeWriteNotification, AccessTokenScopeReadNotification,
	AccessTokenScopeWriteOrganization, AccessTokenScopeReadOrganization,
	AccessTokenScopeWritePackage, AccessTokenScopeReadPackage,
	AccessTokenScopeWriteIssue, AccessTokenScopeReadIssue,
	AccessTokenScopeWriteRepository, AccessTokenScopeReadRepository,
	AccessTokenScopeWriteUser, AccessTokenScopeReadUser,
}

// allAccessTokenScopeBits contains all access token scopes.
var allAccessTokenScopeBits = map[AccessTokenScope]accessTokenScopeBitmap{
	AccessTokenScopeAll:               accessTokenScopeAllBits,
	AccessTokenScopePublicOnly:        accessTokenScopePublicOnlyBits,
	AccessTokenScopeReadActivityPub:   accessTokenScopeReadActivityPubBits,
	AccessTokenScopeWriteActivityPub:  accessTokenScopeWriteActivityPubBits,
	AccessTokenScopeReadAdmin:         accessTokenScopeReadAdminBits,
	AccessTokenScopeWriteAdmin:        accessTokenScopeWriteAdminBits,
	AccessTokenScopeReadMisc:          accessTokenScopeReadMiscBits,
	AccessTokenScopeWriteMisc:         accessTokenScopeWriteMiscBits,
	AccessTokenScopeReadNotification:  accessTokenScopeReadNotificationBits,
	AccessTokenScopeWriteNotification: accessTokenScopeWriteNotificationBits,
	AccessTokenScopeReadOrganization:  accessTokenScopeReadOrganizationBits,
	AccessTokenScopeWriteOrganization: accessTokenScopeWriteOrganizationBits,
	AccessTokenScopeReadPackage:       accessTokenScopeReadPackageBits,
	AccessTokenScopeWritePackage:      accessTokenScopeWritePackageBits,
	AccessTokenScopeReadIssue:         accessTokenScopeReadIssueBits,
	AccessTokenScopeWriteIssue:        accessTokenScopeWriteIssueBits,
	AccessTokenScopeReadRepository:    accessTokenScopeReadRepositoryBits,
	AccessTokenScopeWriteRepository:   accessTokenScopeWriteRepositoryBits,
	AccessTokenScopeReadUser:          accessTokenScopeReadUserBits,
	AccessTokenScopeWriteUser:         accessTokenScopeWriteUserBits,
}

// hasScope returns true if the string has the given scope
func (bitmap accessTokenScopeBitmap) hasScope(scope AccessTokenScope) (bool, error) {
	expectedBits, ok := allAccessTokenScopeBits[scope]
	if !ok {
		return false, fmt.Errorf("invalid access token scope: %s", scope)
	}

	return bitmap&expectedBits == expectedBits, nil
}

// toScope returns a normalized scope string without any duplicates.
func (bitmap accessTokenScopeBitmap) toScope(unknownScopes *[]unknownAccessTokenScope) AccessTokenScope {
	var scopes []string

	// Preserve unknown scopes, and put them at the beginning so that it's clear
	// when debugging.
	if unknownScopes != nil {
		for _, unknownScope := range *unknownScopes {
			scopes = append(scopes, string(unknownScope))
		}
	}

	// iterate over all scopes, and reconstruct the bitmap
	// if the reconstructed bitmap doesn't change, then the scope is already included
	var reconstruct accessTokenScopeBitmap

	for _, singleScope := range allAccessTokenScopes {
		// no need for error checking here, since we know the scope is valid
		if ok, _ := bitmap.hasScope(singleScope); ok {
			current := reconstruct | allAccessTokenScopeBits[singleScope]
			if current == reconstruct {
				continue
			}

			reconstruct = current
			scopes = append(scopes, string(singleScope))
		}
	}

	scope := AccessTokenScope(strings.Join(scopes, ","))
	scope = AccessTokenScope(strings.ReplaceAll(
		string(scope),
		"write:activitypub,write:admin,write:misc,write:notification,write:organization,write:package,write:issue,write:repository,write:user",
		"all",
	))
	return scope
}

// parse the scope string into a bitmap, thus removing possible duplicates.
func (s AccessTokenScope) parse() (accessTokenScopeBitmap, *[]unknownAccessTokenScope) {
	var bitmap accessTokenScopeBitmap
	var unknownScopes []unknownAccessTokenScope

	// The following is the more performant equivalent of 'for _, v := range strings.Split(remainingScope, ",")' as this is hot code
	remainingScopes := string(s)
	for len(remainingScopes) > 0 {
		i := strings.IndexByte(remainingScopes, ',')
		var v string
		if i < 0 {
			v = remainingScopes
			remainingScopes = ""
		} else if i+1 >= len(remainingScopes) {
			v = remainingScopes[:i]
			remainingScopes = ""
		} else {
			v = remainingScopes[:i]
			remainingScopes = remainingScopes[i+1:]
		}
		singleScope := AccessTokenScope(v)
		if singleScope == "" {
			continue
		}
		if singleScope == AccessTokenScopeAll {
			bitmap |= accessTokenScopeAllBits
			continue
		}

		bits, ok := allAccessTokenScopeBits[singleScope]
		if !ok {
			unknownScopes = append(unknownScopes, unknownAccessTokenScope(string(singleScope)))
		}
		bitmap |= bits
	}

	return bitmap, &unknownScopes
}

// NormalizePreservingUnknown returns a normalized scope string without any
// duplicates.  Unknown scopes are included.
func (s AccessTokenScope) NormalizePreservingUnknown() AccessTokenScope {
	bitmap, unknownScopes := s.parse()

	return bitmap.toScope(unknownScopes)
}

// OldAccessTokenScope represents the scope for an access token.
type OldAccessTokenScope string

const (
	OldAccessTokenScopeAll OldAccessTokenScope = "all"

	OldAccessTokenScopeRepo       OldAccessTokenScope = "repo"
	OldAccessTokenScopeRepoStatus OldAccessTokenScope = "repo:status"
	OldAccessTokenScopePublicRepo OldAccessTokenScope = "public_repo"

	OldAccessTokenScopeAdminOrg OldAccessTokenScope = "admin:org"
	OldAccessTokenScopeWriteOrg OldAccessTokenScope = "write:org"
	OldAccessTokenScopeReadOrg  OldAccessTokenScope = "read:org"

	OldAccessTokenScopeAdminPublicKey OldAccessTokenScope = "admin:public_key"
	OldAccessTokenScopeWritePublicKey OldAccessTokenScope = "write:public_key"
	OldAccessTokenScopeReadPublicKey  OldAccessTokenScope = "read:public_key"

	OldAccessTokenScopeAdminRepoHook OldAccessTokenScope = "admin:repo_hook"
	OldAccessTokenScopeWriteRepoHook OldAccessTokenScope = "write:repo_hook"
	OldAccessTokenScopeReadRepoHook  OldAccessTokenScope = "read:repo_hook"

	OldAccessTokenScopeAdminOrgHook OldAccessTokenScope = "admin:org_hook"

	OldAccessTokenScopeNotification OldAccessTokenScope = "notification"

	OldAccessTokenScopeUser       OldAccessTokenScope = "user"
	OldAccessTokenScopeReadUser   OldAccessTokenScope = "read:user"
	OldAccessTokenScopeUserEmail  OldAccessTokenScope = "user:email"
	OldAccessTokenScopeUserFollow OldAccessTokenScope = "user:follow"

	OldAccessTokenScopeDeleteRepo OldAccessTokenScope = "delete_repo"

	OldAccessTokenScopePackage       OldAccessTokenScope = "package"
	OldAccessTokenScopeWritePackage  OldAccessTokenScope = "write:package"
	OldAccessTokenScopeReadPackage   OldAccessTokenScope = "read:package"
	OldAccessTokenScopeDeletePackage OldAccessTokenScope = "delete:package"

	OldAccessTokenScopeAdminGPGKey OldAccessTokenScope = "admin:gpg_key"
	OldAccessTokenScopeWriteGPGKey OldAccessTokenScope = "write:gpg_key"
	OldAccessTokenScopeReadGPGKey  OldAccessTokenScope = "read:gpg_key"

	OldAccessTokenScopeAdminApplication OldAccessTokenScope = "admin:application"
	OldAccessTokenScopeWriteApplication OldAccessTokenScope = "write:application"
	OldAccessTokenScopeReadApplication  OldAccessTokenScope = "read:application"

	OldAccessTokenScopeSudo OldAccessTokenScope = "sudo"
)

var accessTokenScopeMap = map[OldAccessTokenScope][]AccessTokenScope{
	OldAccessTokenScopeAll:              {AccessTokenScopeAll},
	OldAccessTokenScopeRepo:             {AccessTokenScopeWriteRepository},
	OldAccessTokenScopeRepoStatus:       {AccessTokenScopeWriteRepository},
	OldAccessTokenScopePublicRepo:       {AccessTokenScopePublicOnly, AccessTokenScopeWriteRepository},
	OldAccessTokenScopeAdminOrg:         {AccessTokenScopeWriteOrganization},
	OldAccessTokenScopeWriteOrg:         {AccessTokenScopeWriteOrganization},
	OldAccessTokenScopeReadOrg:          {AccessTokenScopeReadOrganization},
	OldAccessTokenScopeAdminPublicKey:   {AccessTokenScopeWriteUser},
	OldAccessTokenScopeWritePublicKey:   {AccessTokenScopeWriteUser},
	OldAccessTokenScopeReadPublicKey:    {AccessTokenScopeReadUser},
	OldAccessTokenScopeAdminRepoHook:    {AccessTokenScopeWriteRepository},
	OldAccessTokenScopeWriteRepoHook:    {AccessTokenScopeWriteRepository},
	OldAccessTokenScopeReadRepoHook:     {AccessTokenScopeReadRepository},
	OldAccessTokenScopeAdminOrgHook:     {AccessTokenScopeWriteOrganization},
	OldAccessTokenScopeNotification:     {AccessTokenScopeWriteNotification},
	OldAccessTokenScopeUser:             {AccessTokenScopeWriteUser},
	OldAccessTokenScopeReadUser:         {AccessTokenScopeReadUser},
	OldAccessTokenScopeUserEmail:        {AccessTokenScopeWriteUser},
	OldAccessTokenScopeUserFollow:       {AccessTokenScopeWriteUser},
	OldAccessTokenScopeDeleteRepo:       {AccessTokenScopeWriteRepository},
	OldAccessTokenScopePackage:          {AccessTokenScopeWritePackage},
	OldAccessTokenScopeWritePackage:     {AccessTokenScopeWritePackage},
	OldAccessTokenScopeReadPackage:      {AccessTokenScopeReadPackage},
	OldAccessTokenScopeDeletePackage:    {AccessTokenScopeWritePackage},
	OldAccessTokenScopeAdminGPGKey:      {AccessTokenScopeWriteUser},
	OldAccessTokenScopeWriteGPGKey:      {AccessTokenScopeWriteUser},
	OldAccessTokenScopeReadGPGKey:       {AccessTokenScopeReadUser},
	OldAccessTokenScopeAdminApplication: {AccessTokenScopeWriteUser},
	OldAccessTokenScopeWriteApplication: {AccessTokenScopeWriteUser},
	OldAccessTokenScopeReadApplication:  {AccessTokenScopeReadUser},
	OldAccessTokenScopeSudo:             {AccessTokenScopeWriteAdmin},
}

type AccessToken struct {
	ID    int64 `xorm:"pk autoincr"`
	Scope string
}

func ConvertScopedAccessTokens(x db.EngineMigration) error {
	var tokens []*AccessToken

	if err := x.Find(&tokens); err != nil {
		return err
	}

	for _, token := range tokens {
		var scopes []string
		allNewScopesMap := make(map[AccessTokenScope]bool)
		for oldScope := range strings.SplitSeq(token.Scope, ",") {
			if newScopes, exists := accessTokenScopeMap[OldAccessTokenScope(oldScope)]; exists {
				for _, newScope := range newScopes {
					allNewScopesMap[newScope] = true
				}
			} else {
				log.Debug("access token scope not recognized as old token scope %s; preserving it", oldScope)
				scopes = append(scopes, oldScope)
			}
		}

		for s := range allNewScopesMap {
			scopes = append(scopes, string(s))
		}
		scope := AccessTokenScope(strings.Join(scopes, ","))

		// normalize the scope
		normScope := scope.NormalizePreservingUnknown()

		token.Scope = string(normScope)

		// update the db entry with the new scope
		if _, err := x.Cols("scope").ID(token.ID).Update(token); err != nil {
			return err
		}
	}

	return nil
}
