package types

import (
	"encoding/json"
	"log"
	"strings"
	"time"

	"github.com/Tencent/WeKnora/internal/utils"
	"github.com/google/uuid"
	"gorm.io/gorm"
)

// Data source types and constants
const (
	// Connector types
	ConnectorTypeFeishu = "feishu"
	// ConnectorTypeLark is Feishu's international edition (open.larksuite.com).
	// It shares the Feishu connector; only the API host and tenant differ.
	ConnectorTypeLark = "lark"
	// ConnectorTypeFeishuDrive is the Feishu Drive (云盘) mode: syncs documents
	// under a user-supplied Drive folder_token, as opposed to a Wiki space.
	// Shares the feishu connector package; only resource enumeration + fetch differ.
	ConnectorTypeFeishuDrive = "feishu_drive"
	// ConnectorTypeLarkDrive is the Lark (international) Drive mode, the
	// international counterpart of ConnectorTypeFeishuDrive.
	ConnectorTypeLarkDrive   = "lark_drive"
	ConnectorTypeNotion      = "notion"
	ConnectorTypeConfluence  = "confluence"
	ConnectorTypeYuque       = "yuque"
	ConnectorTypeGitHub      = "github"
	ConnectorTypeGoogleDrive = "google_drive"
	ConnectorTypeOneDrive    = "onedrive"
	ConnectorTypeDingTalk    = "dingtalk"
	ConnectorTypeWebCrawler  = "web_crawler"
	ConnectorTypeSlack       = "slack"
	ConnectorTypeIMAP        = "imap"
	ConnectorTypeRSS         = "rss"
	ConnectorTypeGitLab      = "gitlab"
	ConnectorTypeIMA         = "ima"

	// Sync modes
	SyncModeIncremental = "incremental"
	SyncModeFull        = "full"

	// Data source status
	DataSourceStatusActive  = "active"
	DataSourceStatusPaused  = "paused"
	DataSourceStatusError   = "error"
	DataSourceStatusDeleted = "deleted"

	// Sync log status
	SyncLogStatusRunning  = "running"
	SyncLogStatusSuccess  = "success"
	SyncLogStatusPartial  = "partial"
	SyncLogStatusFailed   = "failed"
	SyncLogStatusCanceled = "canceled"

	// Conflict resolution strategies
	ConflictStrategyOverwrite = "overwrite"
	ConflictStrategySkip      = "skip"
)

// DataSource represents a configured external data source for synchronization
type DataSource struct {
	// Unique identifier
	ID string `json:"id" gorm:"type:varchar(36);primaryKey"`

	// Workspace ID for multi-workspace isolation
	TenantID uint64 `json:"tenant_id" gorm:"index"`

	// Target knowledge base ID
	KnowledgeBaseID string `json:"knowledge_base_id" gorm:"index"`

	// User-friendly name
	Name string `json:"name"`

	// Connector type (feishu, notion, confluence, etc.)
	Type string `json:"type" gorm:"type:varchar(50);index"`

	// Encrypted configuration (API credentials, tokens, etc.)
	// Stored as JSON with AES-256-GCM encryption
	Config JSON `json:"config" gorm:"type:jsonb"`

	// Cron expression for scheduled syncs (e.g., "0 */6 * * *" = every 6 hours)
	SyncSchedule string `json:"sync_schedule"`

	// Sync mode: "incremental" (recommended) or "full"
	SyncMode string `json:"sync_mode" gorm:"type:varchar(20);default:'incremental'"`

	// Current status: active, paused, error
	Status string `json:"status" gorm:"type:varchar(32);default:'active'"`

	// Conflict resolution strategy: overwrite or skip
	ConflictStrategy string `json:"conflict_strategy" gorm:"type:varchar(32);default:'overwrite'"`

	// Whether to sync deletions from source
	SyncDeletions bool `json:"sync_deletions" gorm:"default:true"`

	// Last successful sync timestamp
	LastSyncAt *time.Time `json:"last_sync_at"`

	// Cursor or state for incremental sync (connector-specific)
	LastSyncCursor JSON `json:"last_sync_cursor" gorm:"type:jsonb"`

	// Summary of last sync result
	LastSyncResult JSON `json:"last_sync_result" gorm:"type:jsonb"`

	// Error message if status is "error"
	ErrorMessage string `json:"error_message"`

	// Number of days to keep sync logs (default: 30)
	SyncLogRetentionDays int `json:"sync_log_retention_days" gorm:"default:30"`

	// Creation timestamp
	CreatedAt time.Time `json:"created_at"`

	// Last update timestamp
	UpdatedAt time.Time `json:"updated_at"`

	// Soft delete timestamp
	DeletedAt gorm.DeletedAt `json:"deleted_at" gorm:"index"`

	// Total items synced (not stored in DB, calculated on query)
	TotalItemsSynced int64 `json:"total_items_synced" gorm:"-"`

	// Latest sync log (not stored in DB, populated on query)
	LatestSyncLog *SyncLog `json:"latest_sync_log" gorm:"-"`
}

// TableName specifies the table name for DataSource
func (d *DataSource) TableName() string {
	return "data_sources"
}

// BeforeCreate hook to generate UUID
func (d *DataSource) BeforeCreate(tx *gorm.DB) error {
	if d.ID == "" {
		d.ID = uuid.New().String()
	}
	return nil
}

// SyncLog records the execution of a sync task
type SyncLog struct {
	// Unique identifier
	ID string `json:"id" gorm:"type:varchar(36);primaryKey"`

	// Reference to the data source
	DataSourceID string `json:"data_source_id" gorm:"index"`

	// Workspace ID
	TenantID uint64 `json:"tenant_id" gorm:"index"`

	// Sync status: running, success, partial, failed, canceled
	Status string `json:"status" gorm:"type:varchar(32);index"`

	// Sync start time
	StartedAt time.Time `json:"started_at"`

	// Sync completion time
	FinishedAt *time.Time `json:"finished_at"`

	// Total items fetched from source
	ItemsTotal int `json:"items_total"`

	// New items created in knowledge base
	ItemsCreated int `json:"items_created"`

	// Existing items updated
	ItemsUpdated int `json:"items_updated"`

	// Items deleted from knowledge base
	ItemsDeleted int `json:"items_deleted"`

	// Items skipped (no changes detected)
	ItemsSkipped int `json:"items_skipped"`

	// Items that failed to sync
	ItemsFailed int `json:"items_failed"`

	// Error details if status is "failed"
	ErrorMessage string `json:"error_message"`

	// Detailed sync result (JSON-encoded)
	Result JSON `json:"result" gorm:"type:jsonb"`

	// Creation timestamp (usually same as StartedAt)
	CreatedAt time.Time `json:"created_at"`

	// Last update timestamp
	UpdatedAt time.Time `json:"updated_at"`
}

// TableName specifies the table name for SyncLog
func (s *SyncLog) TableName() string {
	return "sync_logs"
}

// BeforeCreate hook to generate UUID
func (s *SyncLog) BeforeCreate(tx *gorm.DB) error {
	if s.ID == "" {
		s.ID = uuid.New().String()
	}
	if s.StartedAt.IsZero() {
		s.StartedAt = time.Now().UTC()
	}
	return nil
}

// DataSourceConfig represents the unencrypted configuration structure
// Each connector type will have its own specific fields.
//
// Credential management lives in the dedicated /credentials subresource
// (see internal/handler/datasource_credentials.go). Secret values are never
// included in API responses — handlers serialize via dto.NewDataSourceResponse
// which strips the Credentials map by construction.
type DataSourceConfig struct {
	// Common fields applicable to most connectors
	Type string `json:"type"`

	// OAuth/API credentials (varies by connector)
	Credentials map[string]interface{} `json:"credentials"`

	// Selected resource IDs to sync (e.g., folder IDs, space IDs)
	ResourceIDs []string `json:"resource_ids"`

	// Connector-specific configuration
	Settings map[string]interface{} `json:"settings"`

	// MultimodalEnabled mirrors the target knowledge base's VLM/multimodal
	// setting for the current sync run. The service populates it before each fetch
	// and it is never persisted (json:"-") — the KB owns the setting. Connectors
	// use it to decide whether extracting embedded images for OCR is worthwhile:
	// ingesting an image into a KB without VLM is rejected, so image extraction is
	// skipped when this is false.
	MultimodalEnabled bool `json:"-"`
}

// HasCredentials reports whether the credentials map carries any value at
// all. Used by the Update path and by the credential subresource to decide
// whether to run live-connector validation.
func (d DataSourceConfig) HasCredentials() bool {
	return len(d.Credentials) > 0
}

// HasConfiguredCredentials reports whether user-facing secret credentials are
// stored. RSS feed URLs are non-secret configuration (settings); only
// auth_headers count as credentials for that connector.
func (d DataSourceConfig) HasConfiguredCredentials(connectorType string) bool {
	if len(d.Credentials) == 0 {
		return false
	}
	switch connectorType {
	case ConnectorTypeRSS:
		raw, ok := d.Credentials["auth_headers"]
		if !ok {
			return false
		}
		s, ok := raw.(string)
		return ok && strings.TrimSpace(s) != ""
	default:
		return len(d.Credentials) > 0
	}
}

// StripNonSecretCredentials removes non-secret values mistakenly stored in the
// credentials map before persistence.
func (d *DataSourceConfig) StripNonSecretCredentials(connectorType string) {
	if d == nil || d.Credentials == nil {
		return
	}
	switch connectorType {
	case ConnectorTypeRSS:
		delete(d.Credentials, "feed_urls")
		if len(d.Credentials) == 0 {
			d.Credentials = nil
		}
	}
}

// Resource represents a syncable resource (document, folder, space) from external system
type Resource struct {
	// Unique identifier in the external system
	ExternalID string `json:"external_id"`

	// Display name
	Name string `json:"name"`

	// Resource type (document, folder, space, page, etc.)
	Type string `json:"type"`

	// Optional description
	Description string `json:"description"`

	// URL to access in external system
	URL string `json:"url"`

	// Last modified time in external system
	ModifiedAt time.Time `json:"modified_at"`

	// For hierarchical resources (parent ID if applicable)
	ParentID string `json:"parent_id,omitempty"`

	// Whether this resource has children that can be expanded
	HasChildren bool `json:"has_children,omitempty"`

	// Additional metadata
	Metadata map[string]interface{} `json:"metadata,omitempty"`
}

// FetchedItem represents a single document/content item fetched from external source
type FetchedItem struct {
	// Unique ID in the external system
	ExternalID string `json:"external_id"`

	// Title of the content
	Title string `json:"title"`

	// Content in bytes (Markdown format preferred)
	Content []byte `json:"content"`

	// MIME type (text/markdown, text/html, application/pdf, etc.)
	ContentType string `json:"content_type"`

	// Suggested file name
	FileName string `json:"file_name"`

	// Original URL in external system
	URL string `json:"url"`

	// When last modified in external system
	UpdatedAt time.Time `json:"updated_at"`

	// Additional metadata to preserve
	Metadata map[string]string `json:"metadata"`

	// Whether the item was deleted in the source
	IsDeleted bool `json:"is_deleted"`

	// Source resource ID (e.g., folder ID this document belongs to)
	SourceResourceID string `json:"source_resource_id"`

	// ReplacesSubtree, when true, tells ingestion to reconcile this item's
	// sub-items: after the parent is (re)ingested, every existing knowledge item
	// whose external_id starts with SubtreeChildPrefix(ExternalID) that is NOT
	// listed in SubtreeKeep is deleted as stale. Used by connectors that fan one
	// source node out into a parent document plus attachment/image sub-items
	// (e.g. Feishu docx).
	//
	// PRECONDITIONS the sweep relies on — a connector setting this MUST honour:
	//   1. Child external_ids are built with SubtreeChildID, so they share the
	//      '#' prefix the sweep matches. A child ID without that prefix is never
	//      swept (silently orphaned); an unrelated item that happens to start
	//      with the prefix would be wrongly swept.
	//   2. The parent is emitted (streaming) / listed (batch) no later than its
	//      children, and SubtreeKeep already names every still-present child when
	//      the parent is ingested. The sweep runs at parent-ingest time against
	//      the PRIOR sync's children, so a child emitted after its parent's sweep
	//      but absent from SubtreeKeep could be deleted right after being added.
	ReplacesSubtree bool `json:"replaces_subtree,omitempty"`

	// SubtreeKeep lists the external_ids of sub-items that still exist in the
	// source this sync. Consulted only when ReplacesSubtree is true: the sweep
	// preserves these children even if they could not be re-ingested this cycle
	// (transient download/parse failure, or an unclassifiable filename), so a
	// still-present attachment never loses its previously-synced good copy. Only
	// children absent from this set — genuinely removed from the source — are
	// swept.
	//
	// CONTRACT: an empty (or nil) SubtreeKeep with ReplacesSubtree=true means
	// "keep nothing" and sweeps EVERY existing child under the prefix. That is
	// correct for a node whose attachments all vanished, so a connector setting
	// ReplacesSubtree MUST populate SubtreeKeep with every child still present.
	// The field is consumed in-process (fetch → ingest, no serialization), so
	// nil and empty are equivalent here; the omitempty tag is for API/debug
	// exposure only and must not be relied on to distinguish "unset" from "empty".
	SubtreeKeep []string `json:"subtree_keep,omitempty"`
}

// SubtreeChildID builds the external_id of a sub-item fanned out from a parent
// source node — e.g. a docx node's attachment or embedded image. The shape is
// "<parentExternalID>#<kind>#<token>". The '#' separator is the contract the
// subtree sweep depends on (see SubtreeChildPrefix and FetchedItem.ReplacesSubtree):
// producers MUST build child IDs with this helper so the producer and the sweep
// consumer share one source of truth. kind is a short discriminator ("file",
// "image"); token is the source system's id for the child and is assumed to be
// '#'-free (Feishu/Notion/etc. tokens are).
func SubtreeChildID(parentExternalID, kind, token string) string {
	return parentExternalID + "#" + kind + "#" + token
}

// SubtreeChildPrefix is the external_id prefix that matches every child of a
// parent node built with SubtreeChildID. The sweep deletes prior children whose
// external_id starts with this prefix and are absent from SubtreeKeep. It must
// move in lockstep with SubtreeChildID: both encode the same '#' separator.
func SubtreeChildPrefix(parentExternalID string) string {
	return parentExternalID + "#"
}

// SyncCursor represents the position/state for incremental sync
// Connector-specific structure allows flexibility
type SyncCursor struct {
	// Timestamp of last sync
	LastSyncTime time.Time `json:"last_sync_time"`

	// Connector-specific cursor (e.g., pagination token, offset, etc.)
	ConnectorCursor map[string]interface{} `json:"connector_cursor"`

	// Hash of the last full sync to detect schema changes
	LastSchemaHash string `json:"last_schema_hash"`
}

// SyncResult summarizes the outcome of a sync operation
type SyncResult struct {
	// Total items processed
	Total int `json:"total"`

	// Items created
	Created int `json:"created"`

	// Items updated
	Updated int `json:"updated"`

	// Items deleted
	Deleted int `json:"deleted"`

	// Items skipped (no changes)
	Skipped int `json:"skipped"`

	// Items that failed
	Failed int `json:"failed"`

	// Deleted items whose KB deletion failed (a subset of Failed). Past the
	// connector cursor, so normally only a later full sync retries them.
	DeletionFailed int `json:"deletion_failed,omitempty"`

	// Per-item failure samples (capped), shown in the sync-log UI.
	Errors []SyncItemError `json:"errors,omitempty"`

	// Updated cursor for next incremental sync
	NextCursor *SyncCursor `json:"next_cursor,omitempty"`
}

// SyncItemError is one user-facing failure sample. It carries a stable i18n
// Code (+ interpolation Params) so the frontend localises it to the viewer's
// language, plus a Message fallback for clients without the key. The raw API
// status/body/log_id is never stored here — that stays in the server logs.
type SyncItemError struct {
	// Title is the document title (user content, not translated).
	Title string `json:"title,omitempty"`
	// Code is a stable key the frontend maps to a localized string, e.g.
	// "feishu_rate_limited" → datasource.syncError.feishu_rate_limited.
	Code string `json:"code,omitempty"`
	// Params are interpolation values for the localized string, e.g. {"code":"1663"}.
	Params map[string]string `json:"params,omitempty"`
	// Message is a human fallback used when the client has no i18n key for Code.
	Message string `json:"message,omitempty"`
}

// Display renders the sample as a single plain string for server-side use
// (logs, fatal-error detail). The localised UI string is built on the frontend
// from Code/Params; this is only a non-localised fallback.
func (e SyncItemError) Display() string {
	switch {
	case e.Title != "" && e.Message != "":
		return e.Title + ": " + e.Message
	case e.Message != "":
		return e.Message
	default:
		return e.Title
	}
}

// UnmarshalJSON keeps old sync logs readable: historically each error was a
// plain JSON string, so a bare string decodes into Message.
func (e *SyncItemError) UnmarshalJSON(b []byte) error {
	var s string
	if err := json.Unmarshal(b, &s); err == nil {
		e.Message = s
		return nil
	}
	type alias SyncItemError
	var a alias
	if err := json.Unmarshal(b, &a); err != nil {
		return err
	}
	*e = SyncItemError(a)
	return nil
}

// DataSourceSyncPayload represents the asynq task payload for data source sync
type DataSourceSyncPayload struct {
	TracingContext
	Initiator TaskInitiator `json:"initiator,omitempty"`
	// Trigger distinguishes a user-requested run from a scheduler-created run.
	Trigger string `json:"trigger,omitempty"`

	// Data source ID to sync
	DataSourceID string `json:"data_source_id"`

	// Workspace ID
	TenantID uint64 `json:"tenant_id"`

	// Sync log ID (for tracking)
	SyncLogID string `json:"sync_log_id"`

	// Force full sync even if incremental mode is configured
	ForceFull bool `json:"force_full"`

	// Maximum number of items to fetch (0 = unlimited)
	MaxItems int `json:"max_items,omitempty"`
}

// ToJSON converts a DataSourceConfig to the JSON blob stored in
// DataSource.Config.
//
// When SYSTEM_AES_KEY is configured, every string value inside
// Credentials is AES-256-GCM encrypted before serialization. Non-string
// values (numbers, bools, nested objects) pass through untouched. This is
// the only write path through which credentials reach the DB (the GORM
// JSON type itself is a byte passthrough), so encrypting here is
// sufficient to keep DataSource.Config at rest fully encrypted.
//
// Encryption operates on a shallow copy of Credentials to avoid mutating
// the caller's in-memory map (subsequent reads would otherwise see
// ciphertext).
func (d *DataSourceConfig) ToJSON() (JSON, error) {
	if d == nil {
		return nil, nil
	}
	out := *d
	if key := utils.GetAESKey(); key != nil && len(out.Credentials) > 0 {
		encCreds := make(map[string]interface{}, len(out.Credentials))
		for k, v := range out.Credentials {
			if s, ok := v.(string); ok && s != "" {
				if enc, err := utils.EncryptAESGCM(s, key); err == nil {
					encCreds[k] = enc
					continue
				}
			}
			encCreds[k] = v
		}
		out.Credentials = encCreds
	}
	bytes, err := json.Marshal(&out)
	if err != nil {
		return nil, err
	}
	return JSON(bytes), nil
}

// ToJSON converts a value to JSON type
func (r *SyncCursor) ToJSON() (JSON, error) {
	if r == nil {
		return nil, nil
	}
	bytes, err := json.Marshal(r)
	if err != nil {
		return nil, err
	}
	return JSON(bytes), nil
}

// ToJSON converts a value to JSON type
func (r *SyncResult) ToJSON() (JSON, error) {
	if r == nil {
		return nil, nil
	}
	bytes, err := json.Marshal(r)
	if err != nil {
		return nil, err
	}
	return JSON(bytes), nil
}

// ParseConfig deserializes DataSource.Config and decrypts any encrypted
// Credentials entries.
//
// DecryptStoredSecret transparently handles three cases per credential:
//   - empty string: untouched
//   - legacy plaintext (no enc:v1: prefix): returned as-is, so historical
//     rows continue to work without a migration step
//   - enc:v1: encrypted: decrypted with SYSTEM_AES_KEY; missing/rotated
//     key surfaces as an error so we fail loudly rather than handing
//     ciphertext to the upstream connector as the credential
func (d *DataSource) ParseConfig() (*DataSourceConfig, error) {
	if len(d.Config) == 0 {
		return nil, nil
	}
	var config DataSourceConfig
	if err := json.Unmarshal(d.Config, &config); err != nil {
		return nil, err
	}
	for k, v := range config.Credentials {
		s, ok := v.(string)
		if !ok || s == "" {
			continue
		}
		if plain, ok := utils.DecryptStoredSecretLenient(s); ok {
			config.Credentials[k] = plain
			continue
		}
		// Same rationale as the other Scan paths: don't fail the load —
		// blank the field so the row stays visible. ParseConfig callers
		// then see an empty credential string; HasCredentials() returns
		// false; the UI surfaces "credential not configured" and the
		// user can re-enter without losing the rest of the data source.
		log.Printf(
			"[crypto] datasource credential %q: decrypt failed (SYSTEM_AES_KEY missing/rotated?), treating as unconfigured",
			k,
		)
		config.Credentials[k] = ""
	}
	return &config, nil
}

// ParseSyncCursor parses the cursor JSON
func (d *DataSource) ParseSyncCursor() (*SyncCursor, error) {
	if len(d.LastSyncCursor) == 0 {
		return nil, nil
	}
	var cursor SyncCursor
	if err := json.Unmarshal(d.LastSyncCursor, &cursor); err != nil {
		return nil, err
	}
	return &cursor, nil
}

// ParseSyncResult parses the result JSON
func (d *DataSource) ParseSyncResult() (*SyncResult, error) {
	if len(d.LastSyncResult) == 0 {
		return nil, nil
	}
	var result SyncResult
	if err := json.Unmarshal(d.LastSyncResult, &result); err != nil {
		return nil, err
	}
	return &result, nil
}

// ParseSyncLogResult parses the result JSON from sync log
func (s *SyncLog) ParseResult() (*SyncResult, error) {
	if len(s.Result) == 0 {
		return nil, nil
	}
	var result SyncResult
	if err := json.Unmarshal(s.Result, &result); err != nil {
		return nil, err
	}
	return &result, nil
}