package permissions

import (
	"bytes"
	"context"
	"fmt"
	"slices"
	"strings"

	"github.com/grafana/grafana/pkg/apimachinery/identity"
	"github.com/grafana/grafana/pkg/services/accesscontrol"
	"github.com/grafana/grafana/pkg/services/dashboards"
	"github.com/grafana/grafana/pkg/services/dashboards/dashboardaccess"
	"github.com/grafana/grafana/pkg/services/featuremgmt"
	"github.com/grafana/grafana/pkg/services/folder"
	"github.com/grafana/grafana/pkg/services/login"
	"github.com/grafana/grafana/pkg/services/sqlstore/searchstore"
)

// maximum possible capacity for recursive queries array: one query for folder and one for dashboard actions
const maximumRecursiveQueries = 2

type clause struct {
	string
	params []any
}

type accessControlDashboardPermissionFilter struct {
	user                identity.Requester
	dashboardAction     string
	dashboardActionSets []string
	folderAction        string
	folderActionSets    []string
	features            featuremgmt.FeatureToggles

	where clause
	// any recursive CTE queries (if supported)
	recQueries                   []clause
	recursiveQueriesAreSupported bool
}

type PermissionsFilter interface {
	LeftJoin() string
	With() (string, []any)
	Where() (string, []any)

	buildClauses()
	nestedFoldersSelectors(permSelector string, permSelectorArgs []any, leftTable string, Col string, rightTableCol string, orgID int64) (string, []any)
}

// NewAccessControlDashboardPermissionFilter creates a new AccessControlDashboardPermissionFilter that is configured with specific actions calculated based on the dashboardaccess.PermissionType and query type
// The filter is configured to use the new permissions filter (without subqueries) if the feature flag is enabled
// The filter is configured to use the old permissions filter (with subqueries) if the feature flag is disabled
func NewAccessControlDashboardPermissionFilter(user identity.Requester, permissionLevel dashboardaccess.PermissionType, queryType string, features featuremgmt.FeatureToggles, recursiveQueriesAreSupported bool) PermissionsFilter {
	needEdit := permissionLevel > dashboardaccess.PERMISSION_VIEW

	var folderAction string
	var dashboardAction string
	var folderActionSets []string
	var dashboardActionSets []string
	if queryType == searchstore.TypeFolder {
		folderAction = dashboards.ActionFoldersRead
		if features.IsEnabled(context.Background(), featuremgmt.FlagAccessActionSets) {
			folderActionSets = []string{"folders:view", "folders:edit", "folders:admin"}
		}
		if needEdit {
			folderAction = dashboards.ActionDashboardsCreate
			if features.IsEnabled(context.Background(), featuremgmt.FlagAccessActionSets) {
				folderActionSets = []string{"folders:edit", "folders:admin"}
			}
		}
	} else if queryType == searchstore.TypeDashboard {
		dashboardAction = dashboards.ActionDashboardsRead
		if features.IsEnabled(context.Background(), featuremgmt.FlagAccessActionSets) {
			folderActionSets = []string{"folders:view", "folders:edit", "folders:admin"}
			dashboardActionSets = []string{"dashboards:view", "dashboards:edit", "dashboards:admin"}
		}
		if needEdit {
			dashboardAction = dashboards.ActionDashboardsWrite
			if features.IsEnabled(context.Background(), featuremgmt.FlagAccessActionSets) {
				folderActionSets = []string{"folders:edit", "folders:admin"}
				dashboardActionSets = []string{"dashboards:edit", "dashboards:admin"}
			}
		}
	} else if queryType == searchstore.TypeAlertFolder {
		folderAction = accesscontrol.ActionAlertingRuleRead
		if features.IsEnabled(context.Background(), featuremgmt.FlagAccessActionSets) {
			folderActionSets = []string{"folders:view", "folders:edit", "folders:admin"}
		}
		if needEdit {
			folderAction = accesscontrol.ActionAlertingRuleCreate
			if features.IsEnabled(context.Background(), featuremgmt.FlagAccessActionSets) {
				folderActionSets = []string{"folders:edit", "folders:admin"}
			}
		}
	} else if queryType == searchstore.TypeAnnotation {
		dashboardAction = accesscontrol.ActionAnnotationsRead
		if features.IsEnabled(context.Background(), featuremgmt.FlagAccessActionSets) {
			folderActionSets = []string{"folders:view", "folders:edit", "folders:admin"}
			dashboardActionSets = []string{"dashboards:view", "dashboards:edit", "dashboards:admin"}
		}
	} else {
		folderAction = dashboards.ActionFoldersRead
		dashboardAction = dashboards.ActionDashboardsRead
		if features.IsEnabled(context.Background(), featuremgmt.FlagAccessActionSets) {
			folderActionSets = []string{"folders:view", "folders:edit", "folders:admin"}
			dashboardActionSets = []string{"dashboards:view", "dashboards:edit", "dashboards:admin"}
		}
		if needEdit {
			folderAction = dashboards.ActionDashboardsCreate
			dashboardAction = dashboards.ActionDashboardsWrite
			if features.IsEnabled(context.Background(), featuremgmt.FlagAccessActionSets) {
				folderActionSets = []string{"folders:edit", "folders:admin"}
				dashboardActionSets = []string{"dashboards:edit", "dashboards:admin"}
			}
		}
	}

	var f PermissionsFilter
	if features.IsEnabledGlobally(featuremgmt.FlagPermissionsFilterRemoveSubquery) {
		f = &accessControlDashboardPermissionFilterNoFolderSubquery{
			accessControlDashboardPermissionFilter: accessControlDashboardPermissionFilter{
				user: user, folderAction: folderAction, folderActionSets: folderActionSets, dashboardAction: dashboardAction, dashboardActionSets: dashboardActionSets,
				features: features, recursiveQueriesAreSupported: recursiveQueriesAreSupported,
			},
		}
	} else {
		f = &accessControlDashboardPermissionFilter{user: user, folderAction: folderAction, folderActionSets: folderActionSets, dashboardAction: dashboardAction, dashboardActionSets: dashboardActionSets,
			features: features, recursiveQueriesAreSupported: recursiveQueriesAreSupported,
		}
	}
	f.buildClauses()
	return f
}

func (f *accessControlDashboardPermissionFilter) LeftJoin() string {
	return ""
}

// Where returns:
// - a where clause for filtering dashboards with expected permissions
// - an array with the query parameters
func (f *accessControlDashboardPermissionFilter) Where() (string, []any) {
	return f.where.string, f.where.params
}

// Check if user has no permissions required for search to skip expensive query
func (f *accessControlDashboardPermissionFilter) hasRequiredActions() bool {
	permissions := f.user.GetPermissions()
	requiredActions := []string{f.folderAction, f.dashboardAction}
	for _, action := range requiredActions {
		if _, ok := permissions[action]; ok {
			return true
		}
	}

	return false
}

func (f *accessControlDashboardPermissionFilter) buildClauses() {
	if f.user == nil || f.user.IsNil() || !f.hasRequiredActions() {
		f.where = clause{string: "(1 = 0)"}
		return
	}
	dashWildcards := accesscontrol.WildcardsFromPrefix(dashboards.ScopeDashboardsPrefix)
	folderWildcards := accesscontrol.WildcardsFromPrefix(dashboards.ScopeFoldersPrefix)

	var userID int64
	if id, err := identity.UserIdentifier(f.user.GetID()); err == nil {
		userID = id
	}

	orgID := f.user.GetOrgID()
	filter, params := accesscontrol.UserRolesFilter(orgID, userID, f.user.GetTeams(), accesscontrol.GetOrgRoles(f.user))
	rolesFilter := " AND role_id IN(SELECT id FROM role " + filter + ") "
	var args []any
	builder := strings.Builder{}
	builder.WriteRune('(')

	permSelector := strings.Builder{}
	var permSelectorArgs []any

	// useSelfContainedPermissions is true if the user's permissions are stored and set from the JWT token
	// currently it's used for the extended JWT module (when the user is authenticated via a JWT token generated by Grafana)
	useSelfContainedPermissions := f.user.IsAuthenticatedBy(login.ExtendedJWTModule)

	if f.dashboardAction != "" {
		toCheckDashboards := actionsToCheck(f.dashboardAction, f.dashboardActionSets, f.user.GetPermissions(), dashWildcards, folderWildcards)
		toCheckFolders := actionsToCheck(f.dashboardAction, f.folderActionSets, f.user.GetPermissions(), dashWildcards, folderWildcards)

		if len(toCheckDashboards) > 0 {
			if !useSelfContainedPermissions {
				builder.WriteString("(dashboard.uid IN (SELECT identifier FROM permission WHERE kind = 'dashboards' AND attribute = 'uid'")
				builder.WriteString(rolesFilter)
				args = append(args, params...)
				if len(toCheckDashboards) == 1 {
					builder.WriteString(" AND action = ?) AND NOT dashboard.is_folder)")
					args = append(args, toCheckDashboards[0])
				} else {
					builder.WriteString(" AND action IN (?" + strings.Repeat(", ?", len(toCheckDashboards)-1) + ")) AND NOT dashboard.is_folder)")
					args = append(args, toCheckDashboards...)
				}
			} else {
				args = getAllowedUIDs(f.dashboardAction, f.user, dashboards.ScopeDashboardsPrefix)

				// Only add the IN clause if we have any dashboards to check
				if len(args) > 0 {
					builder.WriteString("(dashboard.uid IN (?" + strings.Repeat(", ?", len(args)-1) + "")
					builder.WriteString(") AND NOT dashboard.is_folder)")
				} else {
					builder.WriteString("(1 = 0)")
				}
			}

			builder.WriteString(" OR ")

			if !useSelfContainedPermissions {
				permSelector.WriteString("(SELECT identifier FROM permission WHERE kind = 'folders' AND attribute = 'uid'")
				permSelector.WriteString(rolesFilter)
				permSelectorArgs = append(permSelectorArgs, params...)
				if len(toCheckDashboards) == 1 {
					permSelector.WriteString(" AND action = ?")
					permSelectorArgs = append(permSelectorArgs, toCheckDashboards[0])
				} else {
					permSelector.WriteString(" AND action IN (?" + strings.Repeat(", ?", len(toCheckDashboards)-1) + ")")
					permSelectorArgs = append(permSelectorArgs, toCheckFolders...)
				}
			} else {
				permSelectorArgs = getAllowedUIDs(f.dashboardAction, f.user, dashboards.ScopeFoldersPrefix)

				// Only add the IN clause if we have any folders to check
				if len(permSelectorArgs) > 0 {
					permSelector.WriteString("(?" + strings.Repeat(", ?", len(permSelectorArgs)-1) + "")
				} else {
					permSelector.WriteString("(")
				}
			}
			permSelector.WriteRune(')')

			switch f.features.IsEnabledGlobally(featuremgmt.FlagNestedFolders) {
			case true:
				if len(permSelectorArgs) > 0 {
					switch f.recursiveQueriesAreSupported {
					case true:
						builder.WriteString("(dashboard.folder_id IN (SELECT d.id FROM dashboard as d ")
						recQueryName := fmt.Sprintf("RecQry%d", len(f.recQueries))
						f.addRecQry(recQueryName, permSelector.String(), permSelectorArgs, orgID)
						builder.WriteString(fmt.Sprintf("WHERE d.org_id = ? AND d.uid IN (SELECT uid FROM %s)", recQueryName))
						args = append(args, orgID)
					default:
						nestedFoldersSelectors, nestedFoldersArgs := f.nestedFoldersSelectors(permSelector.String(), permSelectorArgs, "dashboard", "folder_id", "d.id", orgID)
						builder.WriteRune('(')
						builder.WriteString(nestedFoldersSelectors)
						args = append(args, nestedFoldersArgs...)
					}
				} else {
					builder.WriteString("(dashboard.folder_id IN (SELECT d.id FROM dashboard as d ")
					builder.WriteString("WHERE 1 = 0")
				}
			default:
				builder.WriteString("(dashboard.folder_id IN (SELECT d.id FROM dashboard as d ")
				if len(permSelectorArgs) > 0 {
					builder.WriteString("WHERE d.org_id = ? AND d.uid IN ")
					args = append(args, orgID)
					builder.WriteString(permSelector.String())
					args = append(args, permSelectorArgs...)
				} else {
					builder.WriteString("WHERE 1 = 0")
				}
			}
			builder.WriteString(") AND NOT dashboard.is_folder)")

			// Include all the dashboards under the root if the user has the required permissions on the root (used to be the General folder)
			if hasAccessToRoot(f.dashboardAction, f.user) {
				builder.WriteString(" OR (dashboard.folder_id = 0 AND NOT dashboard.is_folder)")
			}
		} else {
			builder.WriteString("NOT dashboard.is_folder")
		}
	}

	// recycle and reuse
	permSelector.Reset()
	permSelectorArgs = permSelectorArgs[:0]

	if f.folderAction != "" {
		if f.dashboardAction != "" {
			builder.WriteString(" OR ")
		}

		toCheck := actionsToCheck(f.folderAction, f.folderActionSets, f.user.GetPermissions(), folderWildcards)

		if len(toCheck) > 0 {
			if !useSelfContainedPermissions {
				permSelector.WriteString("(SELECT identifier FROM permission WHERE kind = 'folders' AND attribute = 'uid'")
				permSelector.WriteString(rolesFilter)
				permSelectorArgs = append(permSelectorArgs, params...)
				if len(toCheck) == 1 {
					permSelector.WriteString(" AND action = ?")
					permSelectorArgs = append(permSelectorArgs, toCheck[0])
				} else {
					permSelector.WriteString(" AND action IN (?" + strings.Repeat(", ?", len(toCheck)-1) + ")")
					permSelectorArgs = append(permSelectorArgs, toCheck...)
				}
			} else {
				permSelectorArgs = getAllowedUIDs(f.folderAction, f.user, dashboards.ScopeFoldersPrefix)

				if len(permSelectorArgs) > 0 {
					permSelector.WriteString("(?" + strings.Repeat(", ?", len(permSelectorArgs)-1) + "")
				} else {
					permSelector.WriteString("(")
				}
			}

			permSelector.WriteRune(')')

			switch f.features.IsEnabledGlobally(featuremgmt.FlagNestedFolders) {
			case true:
				if len(permSelectorArgs) > 0 {
					switch f.recursiveQueriesAreSupported {
					case true:
						recQueryName := fmt.Sprintf("RecQry%d", len(f.recQueries))
						f.addRecQry(recQueryName, permSelector.String(), permSelectorArgs, orgID)
						builder.WriteString("(dashboard.uid IN ")
						builder.WriteString(fmt.Sprintf("(SELECT uid FROM %s)", recQueryName))
					default:
						nestedFoldersSelectors, nestedFoldersArgs := f.nestedFoldersSelectors(permSelector.String(), permSelectorArgs, "dashboard", "uid", "d.uid", orgID)
						builder.WriteRune('(')
						builder.WriteString(nestedFoldersSelectors)
						builder.WriteRune(')')
						args = append(args, nestedFoldersArgs...)
					}
				} else {
					builder.WriteString("(1 = 0")
				}
			default:
				if len(permSelectorArgs) > 0 {
					builder.WriteString("(dashboard.uid IN ")
					builder.WriteString(permSelector.String())
					args = append(args, permSelectorArgs...)
				} else {
					builder.WriteString("(1 = 0")
				}
			}
			builder.WriteString(" AND dashboard.is_folder)")
		} else {
			builder.WriteString("dashboard.is_folder")
		}
	}

	builder.WriteRune(')')

	f.where = clause{string: builder.String(), params: args}
}

// With returns:
// - a with clause for fetching folders with inherited permissions if nested folders are enabled or an empty string
func (f *accessControlDashboardPermissionFilter) With() (string, []any) {
	var sb bytes.Buffer
	var params []any
	if len(f.recQueries) > 0 {
		sb.WriteString("WITH RECURSIVE ")
		sb.WriteString(f.recQueries[0].string)
		params = append(params, f.recQueries[0].params...)
		for _, r := range f.recQueries[1:] {
			sb.WriteRune(',')
			sb.WriteString(r.string)
			params = append(params, r.params...)
		}
	}
	return sb.String(), params
}

func (f *accessControlDashboardPermissionFilter) addRecQry(queryName string, whereUIDSelect string, whereParams []any, orgID int64) {
	if f.recQueries == nil {
		f.recQueries = make([]clause, 0, maximumRecursiveQueries)
	}
	c := make([]any, len(whereParams))
	copy(c, whereParams)
	c = append([]any{orgID}, c...)
	f.recQueries = append(f.recQueries, clause{
		// covered by UQE_folder_org_id_uid and UQE_folder_org_id_parent_uid_title
		string: fmt.Sprintf(`%s AS (
			SELECT uid, parent_uid, org_id FROM folder WHERE org_id = ? AND uid IN %s
			UNION ALL SELECT f.uid, f.parent_uid, f.org_id FROM folder f INNER JOIN %s r ON f.parent_uid = r.uid and f.org_id = r.org_id
		)`, queryName, whereUIDSelect, queryName),
		params: c,
	})
}

func actionsToCheck(action string, actionSets []string, permissions map[string][]string, wildcards ...accesscontrol.Wildcards) []any {
	for _, scope := range permissions[action] {
		for _, w := range wildcards {
			if w.Contains(scope) {
				return []any{}
			}
		}
	}

	toCheck := []any{action}
	for _, a := range actionSets {
		toCheck = append(toCheck, a)
	}

	return toCheck
}

func (f *accessControlDashboardPermissionFilter) nestedFoldersSelectors(permSelector string, permSelectorArgs []any, leftTable string, leftCol string, rightTableCol string, orgID int64) (string, []any) {
	wheres := make([]string, 0, folder.MaxNestedFolderDepth+1)
	args := make([]any, 0, len(permSelectorArgs)*(folder.MaxNestedFolderDepth+1))

	joins := make([]string, 0, folder.MaxNestedFolderDepth+2)

	// covered by UQE_folder_org_id_uid
	tmpl := "INNER JOIN folder %s ON %s.%s = %s.uid AND %s.org_id = %s.org_id "

	prev := "d"
	onCol := "uid"
	for i := 1; i <= folder.MaxNestedFolderDepth+2; i++ {
		t := fmt.Sprintf("f%d", i)
		s := fmt.Sprintf(tmpl, t, prev, onCol, t, prev, t)
		joins = append(joins, s)

		// covered by UQE_folder_org_id_uid
		wheres = append(wheres, fmt.Sprintf("(%s.org_id = ? AND %s.%s IN (SELECT %s FROM dashboard d %s WHERE %s.org_id = ? AND %s.uid IN %s)", leftTable, leftTable, leftCol, rightTableCol, strings.Join(joins, " "), t, t, permSelector))
		args = append(args, orgID, orgID)
		args = append(args, permSelectorArgs...)

		prev = t
		onCol = "parent_uid"
	}

	return strings.Join(wheres, ") OR "), args
}

func getAllowedUIDs(action string, user identity.Requester, scopePrefix string) []any {
	uidScopes := user.GetPermissions()[action]

	args := make([]any, 0, len(uidScopes))
	for _, uidScope := range uidScopes {
		if !strings.HasPrefix(uidScope, scopePrefix) {
			continue
		}
		uid := strings.TrimPrefix(uidScope, scopePrefix)
		args = append(args, uid)
	}

	return args
}

// Checks if the user has the required permissions on the root (used to be the General folder)
func hasAccessToRoot(actionToCheck string, user identity.Requester) bool {
	generalFolderScope := dashboards.ScopeFoldersProvider.GetResourceScopeUID(folder.GeneralFolderUID)
	return slices.Contains(user.GetPermissions()[actionToCheck], generalFolderScope)
}