package audit

import (
	"RenewCMS/internal/domain/user"
	"errors"
	"slices"
	"strconv"
	"strings"
	"time"
)

var ErrInvalidFilter = errors.New("invalid activity filter")
var ErrInvalidRetention = errors.New("invalid activity retention period")
var ErrInvalidEvent = errors.New("invalid activity event")
var ErrActorNotAllowed = errors.New("activity of another actor is not allowed")

type ActorType string

const (
	ActorUser      ActorType = "user"
	ActorAPIKey    ActorType = "api_key"
	ActorSystem    ActorType = "system"
	ActorAnonymous ActorType = "anonymous"
)

type Category string

const (
	CategoryArticles Category = "articles"
	CategoryMedia    Category = "media"
	CategoryUsers    Category = "users"
	CategoryAPIKeys  Category = "api_keys"
	CategoryAuth     Category = "auth"
	CategorySystem   Category = "system"
	CategorySites    Category = "sites"
	CategoryAuthors  Category = "authors"
)

type Outcome string

const (
	OutcomeSuccess Outcome = "success"
	OutcomeFailed  Outcome = "failed"
)

type Source string

const (
	SourceWeb    Source = "web"
	SourceAPIKey Source = "api_key"
	SourceSystem Source = "system"
)

type ChangeKind string

const (
	ChangeText ChangeKind = "text"
	ChangeBody ChangeKind = "body"
)

const (
	ActionLogin                = "auth.login"
	ActionLoginFailed          = "auth.login_failed"
	ActionLogout               = "auth.logout"
	ActionPasswordResetRequest = "auth.password_reset_requested"
	ActionPasswordResetDone    = "auth.password_reset_completed"
	ActionAPIKeyCreate         = "api_key.create"
	ActionAPIKeyRevoke         = "api_key.revoke"
	ActionRetentionChanged     = "system.activity_retention_changed"
	ActionCleanup              = "system.activity_cleanup"
	ActionArticleCreate        = "article.create"
	ActionArticleEdit          = "article.edit"
	ActionArticlePublish       = "article.publish"
	ActionArticleUnpublish     = "article.unpublish"
	ActionArticleDelete        = "article.delete"
	ActionSiteCreate           = "site.create"
	ActionSiteEdit             = "site.edit"
	ActionSiteSetDefault       = "site.set_default"
	ActionSiteDelete           = "site.delete"
	ActionAuthorCreate         = "author.create"
	ActionAuthorEdit           = "author.edit"
	ActionAuthorDelete         = "author.delete"
	ActionMediaUpload          = "media.upload"
	ActionMediaRename          = "media.rename"
	ActionMediaDelete          = "media.delete"
	ActionMediaMerge           = "media.merge"
	ActionMediaPurge           = "media.purge"
	ActionVariantCreate        = "media.variant_create"
	ActionVariantUpdate        = "media.variant_update"
	ActionVariantDelete        = "media.variant_delete"
	ActionVariantEnable        = "media.variant_enable"
	ActionVariantDisable       = "media.variant_disable"
	ActionVariantPurge         = "media.variant_purge"
	ActionVariantGenerateAll   = "media.variant_generate_all"
	ActionVariantPurgeImage    = "media.variant_purge_image"
	ActionVariantPurgeAll      = "media.variant_purge_all"
	ActionVariantPurgeUnused   = "media.variant_purge_unused"
	ActionUserRegister         = "user.register"
	ActionUserVerify           = "user.verify"
	ActionUserUpdateProfile    = "user.update_profile"
	ActionInviteCreate         = "invite.create"
	ActionInviteCancel         = "invite.cancel"
	ActionInviteRenew          = "invite.renew"
	ActionInviteAccept         = "invite.accept"
	ActionMediaPurgeScheduled  = "system.media_purge"
	ActionUpdateChecked        = "system.update_checked"
	ActionUpdateDownloaded     = "system.update_downloaded"
	ActionRestartRequested     = "system.restart_requested"
)

const (
	TargetAPIKey  = "api_key"
	TargetUser    = "user"
	TargetArticle = "article"
	TargetImage   = "image"
	TargetVariant = "image_variant"
	TargetInvite  = "invite"
	TargetRelease = "release"
	TargetSite    = "site"
	TargetAuthor  = "author"
)

const (
	SystemActorName      = "System"
	ReasonWrongLogin     = "Wrong username or password."
	MaxUserAgentLength   = 255
	ParamRemoved         = "removed"
	ParamFrom            = "from"
	ParamTo              = "to"
	ParamMaxGBFrom       = "max_gb_from"
	ParamMaxGBTo         = "max_gb_to"
	ParamMerged          = "merged"
	ParamArticlesUpdated = "articles_updated"
	ParamFailedGroups    = "failed_groups"
	ParamUpdateAvailable = "update_available"
	ParamKind            = "kind"
	ParamPurgedFiles     = "purged_files"
	ParamPurgedBytes     = "purged_bytes"
	ParamFailedFiles     = "failed_files"
	ParamOlderThanDays   = "older_than_days"
	ParamGenerated       = "generated"
	ParamFailed          = "failed"
	ParamCauses          = "causes"
	ParamWidth           = "width"
	ParamHeight          = "height"
	ParamFit             = "fit"
	ParamFormat          = "format"
	ParamQuality         = "quality"
	ParamTag             = "tag"
	FieldTitle           = "title"
	FieldOnline          = "online"
	FieldBody            = "body"
	FieldFilename        = "filename"
	FieldDisplayName     = "display_name"
	FieldWidth           = "width"
	FieldHeight          = "height"
	FieldFit             = "fit"
	FieldFormat          = "format"
	FieldQuality         = "quality"
	FieldName            = "name"
	FieldBaseURL         = "base_url"
	FieldDefaultRobots   = "default_robots"
	FieldLocale          = "locale"
	FieldSocialImage     = "default_social_image"
	FieldSite            = "site"
	FieldSlug            = "slug"
	FieldBio             = "bio"
	FieldWebsite         = "website"
	FieldSocialLinks     = "social_links"
	FieldAvatar          = "avatar"
	FieldUser            = "user"
	FieldAuthors         = "authors"
	maxNameLength        = 255
	maxActionLength      = 64
	maxFailureReasonSize = 255
)

func ActorTypes() []ActorType {
	return []ActorType{ActorUser, ActorAPIKey, ActorSystem, ActorAnonymous}
}

func Categories() []Category {
	return []Category{CategoryArticles, CategoryMedia, CategoryUsers, CategoryAPIKeys, CategoryAuth, CategorySystem, CategorySites, CategoryAuthors}
}

func Outcomes() []Outcome {
	return []Outcome{OutcomeSuccess, OutcomeFailed}
}

func Sources() []Source {
	return []Source{SourceWeb, SourceAPIKey, SourceSystem}
}

func ChangeKinds() []ChangeKind {
	return []ChangeKind{ChangeText, ChangeBody}
}

type Actor struct {
	Type ActorType `json:"type"`
	ID   *uint32   `json:"id"`
	Name string    `json:"name"`
}

type Target struct {
	Type string `json:"type"`
	ID   string `json:"id"`
	Name string `json:"name"`
}

type Change struct {
	Field  string     `json:"field"`
	Kind   ChangeKind `json:"kind"`
	Before *string    `json:"before,omitempty"`
	After  *string    `json:"after,omitempty"`
	Delta  *int       `json:"delta,omitempty"`
}

type Event struct {
	ID            uint64         `json:"id"`
	CreatedAt     time.Time      `json:"created_at"`
	Action        string         `json:"action"`
	Category      Category       `json:"category"`
	Actor         Actor          `json:"actor"`
	Target        Target         `json:"target"`
	Outcome       Outcome        `json:"outcome"`
	FailureReason *string        `json:"failure_reason"`
	Security      bool           `json:"security"`
	Source        Source         `json:"source"`
	IP            *string        `json:"ip"`
	UserAgent     *string        `json:"user_agent"`
	Params        map[string]any `json:"params"`
	Changes       []Change       `json:"changes"`
}

func NewEvent(action string, category Category) Event {
	return Event{
		Action:   action,
		Category: category,
		Outcome:  OutcomeSuccess,
		Params:   map[string]any{},
		Changes:  []Change{},
	}
}

func SystemActor() Actor {
	return Actor{Type: ActorSystem, Name: SystemActorName}
}

func UserActor(u user.User) Actor {
	id := u.ID
	name := strings.TrimSpace(u.DisplayName)
	if name == "" {
		name = u.Username
	}
	return Actor{Type: ActorUser, ID: &id, Name: name}
}

func AnonymousActor(name string) Actor {
	return Actor{Type: ActorAnonymous, Name: name}
}

func APIKeyActor(id uint32, name string) Actor {
	return Actor{Type: ActorAPIKey, ID: &id, Name: name}
}

func APIKeyTarget(id uint32, name string) Target {
	return Target{Type: TargetAPIKey, ID: strconv.FormatUint(uint64(id), 10), Name: name}
}

func (e Event) Validate() error {
	if e.Action == "" || len(e.Action) > maxActionLength {
		return ErrInvalidEvent
	}
	if !slices.Contains(Categories(), e.Category) || !slices.Contains(Outcomes(), e.Outcome) || !slices.Contains(Sources(), e.Source) || !slices.Contains(ActorTypes(), e.Actor.Type) {
		return ErrInvalidEvent
	}
	if e.FailureReason != nil && len(*e.FailureReason) > maxFailureReasonSize {
		return ErrInvalidEvent
	}
	for _, change := range e.Changes {
		if change.Kind != ChangeText && change.Kind != ChangeBody {
			return ErrInvalidEvent
		}
	}
	return nil
}

func (e Event) Truncated() Event {
	e.Actor.Name = truncate(e.Actor.Name, maxNameLength)
	e.Target.Name = truncate(e.Target.Name, maxNameLength)
	return e
}

func truncate(value string, limit int) string {
	runes := []rune(value)
	return string(runes[:min(len(runes), limit)])
}