package knowledgeversion

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"time"

	"github.com/Tencent/WeKnora/internal/types"
	"gorm.io/gorm"
)

// GraphRecord retains original evidence IDs and payloads in each independent KB.
type GraphRecord struct {
	TenantID             uint64 `gorm:"primaryKey"`
	KnowledgeBaseID      string `gorm:"primaryKey"`
	SourceTable          string `gorm:"primaryKey"`
	LegacyID             int64  `gorm:"primaryKey;autoIncrement:false"`
	GraphVersionID       int64
	Payload              types.JSON `gorm:"type:jsonb"`
	SourceSnapshotSHA256 string     `gorm:"column:source_snapshot_sha256"`
	ImportedAt           time.Time
}

func (GraphRecord) TableName() string { return "native_graph_records" }

type GraphSource struct {
	TenantID            uint64 `gorm:"primaryKey"`
	KnowledgeBaseID     string `gorm:"primaryKey"`
	SourceChunkID       string `gorm:"primaryKey"`
	SourceFile          string
	SourceContentHash   string
	Excerpt             string
	NativeKnowledgeID   *string
	NativeChunkID       *string
	NativeContentSHA256 *string `gorm:"column:native_content_sha256"`
	MappingState        string
}

func (GraphSource) TableName() string { return "native_graph_sources" }

func GraphTablesExist(db *gorm.DB) bool {
	return db.Migrator().HasTable(&GraphRecord{}) && db.Migrator().HasTable(&GraphSource{})
}

// GraphFingerprint participates in approval conflict detection without exposing
// source paths, legacy payloads or private document identifiers to reviewers.
func GraphFingerprint(db *gorm.DB, tenant uint64, kb string) (string, error) {
	if !GraphTablesExist(db) {
		return "", nil
	}
	h := sha256.New()
	count := 0
	for _, item := range []struct {
		model any
		order string
	}{
		{&GraphRecord{}, "source_table, legacy_id"}, {&GraphSource{}, "source_chunk_id"},
	} {
		rows, err := db.Model(item.model).Where("tenant_id=? AND knowledge_base_id=?", tenant, kb).Order(item.order).Rows()
		if err != nil {
			return "", err
		}
		for rows.Next() {
			var value any = &GraphRecord{}
			if _, ok := item.model.(*GraphSource); ok {
				value = &GraphSource{}
			}
			if err := db.ScanRows(rows, value); err != nil {
				rows.Close()
				return "", err
			}
			if err := json.NewEncoder(h).Encode(value); err != nil {
				rows.Close()
				return "", err
			}
			count++
		}
		err = rows.Err()
		rows.Close()
		if err != nil {
			return "", err
		}
	}
	if count == 0 {
		return "", nil
	}
	return hex.EncodeToString(h.Sum(nil)), nil
}

func DeleteGraph(db *gorm.DB, tenant uint64, kb string) error {
	if !GraphTablesExist(db) {
		return nil
	}
	for _, model := range []any{&GraphSource{}, &GraphRecord{}} {
		if err := db.Where("tenant_id=? AND knowledge_base_id=?", tenant, kb).Delete(model).Error; err != nil {
			return err
		}
	}
	return nil
}