package model

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"time"

	"go.yandata.net/iod/iod/go-trustlog/api/logger"
	"go.yandata.net/iod/iod/go-trustlog/internal/helpers"
)

//
// ===== 操作来源类型 =====
//

// Source 表示操作来源，用于区分不同系统模块（IRP、DOIP）。
type Source string

const (
	OpSourceIRP  Source = "IRP"
	OpSourceDOIP Source = "DOIP"
)

//
// ===== 操作代码枚举 (OpCode) =====
//

// OpCode 表示操作的具体代码（int32类型）
type OpCode int32

// 标准 Handle System 操作代码
const (
	OpCodeReserved    OpCode = 0 // Reserved
	OpCodeResolution  OpCode = 1 // Identifier query
	OpCodeGetSiteInfo OpCode = 2 // Get HS_SITE element

	OpCodeCreateID            OpCode = 100 // Create new identifier
	OpCodeDeleteID            OpCode = 101 // Delete existing identifier
	OpCodeAddElement          OpCode = 102 // Add element(s)
	OpCodeRemoveElement       OpCode = 103 // Remove element(s)
	OpCodeModifyElement       OpCode = 104 // Modify element(s)
	OpCodeListIDs             OpCode = 105 // List identifiers
	OpCodeListDerivedPrefixes OpCode = 106 // List derived prefixes

	OpCodeChallengeResponse OpCode = 200 // Response to challenge
	OpCodeVerifyResponse    OpCode = 201 // Verify challenge response

	OpCodeHomePrefix        OpCode = 300 // Home prefix
	OpCodeUnhomePrefix      OpCode = 301 // Unhome prefix
	OpCodeListHomedPrefixes OpCode = 302 // List homed prefixes

	OpCodeSessionSetup     OpCode = 400 // Session setup request
	OpCodeSessionTerminate OpCode = 401 // Session termination request

	// Yandata 扩展操作代码
	OpCodeQueryIDs      OpCode = 500 // Query DOIDs
	OpCodeRenameID      OpCode = 501 // Rename DOID
	OpCodeResolveAltID  OpCode = 502 // Resolve by alternative ID
	OpCodeRegisterAltID OpCode = 503 // Register alternative ID
)

// OpCodeName 返回操作代码的名称
func (c OpCode) String() string {
	switch c {
	case OpCodeReserved:
		return "RESERVED"
	case OpCodeResolution:
		return "RESOLUTION"
	case OpCodeGetSiteInfo:
		return "GET_SITEINFO"
	case OpCodeCreateID:
		return "CREATE_ID"
	case OpCodeDeleteID:
		return "DELETE_ID"
	case OpCodeAddElement:
		return "ADD_ELEMENT"
	case OpCodeRemoveElement:
		return "REMOVE_ELEMENT"
	case OpCodeModifyElement:
		return "MODIFY_ELEMENT"
	case OpCodeListIDs:
		return "LIST_IDS"
	case OpCodeListDerivedPrefixes:
		return "LIST_DERIVED_PREFIXES"
	case OpCodeChallengeResponse:
		return "CHALLENGE_RESPONSE"
	case OpCodeVerifyResponse:
		return "VERIFY_RESPONSE"
	case OpCodeHomePrefix:
		return "HOME_PREFIX"
	case OpCodeUnhomePrefix:
		return "UNHOME_PREFIX"
	case OpCodeListHomedPrefixes:
		return "LIST_HOMED_PREFIXES"
	case OpCodeSessionSetup:
		return "SESSION_SETUP"
	case OpCodeSessionTerminate:
		return "SESSION_TERMINATE"
	case OpCodeQueryIDs:
		return "QUERY_IDS"
	case OpCodeRenameID:
		return "RENAME_ID"
	case OpCodeResolveAltID:
		return "RESOLVE_ALT_ID"
	case OpCodeRegisterAltID:
		return "REGISTER_ALT_ID"
	default:
		return fmt.Sprintf("UNKNOWN(%d)", c)
	}
}

// IsValid 检查操作代码是否有效
func (c OpCode) IsValid() bool {
	validCodes := []OpCode{
		OpCodeReserved, OpCodeResolution, OpCodeGetSiteInfo,
		OpCodeCreateID, OpCodeDeleteID, OpCodeAddElement,
		OpCodeRemoveElement, OpCodeModifyElement, OpCodeListIDs,
		OpCodeListDerivedPrefixes,
		OpCodeChallengeResponse, OpCodeVerifyResponse,
		OpCodeHomePrefix, OpCodeUnhomePrefix, OpCodeListHomedPrefixes,
		OpCodeSessionSetup, OpCodeSessionTerminate,
		OpCodeQueryIDs, OpCodeRenameID, OpCodeResolveAltID, OpCodeRegisterAltID,
	}

	for _, valid := range validCodes {
		if c == valid {
			return true
		}
	}
	return false
}

//
// ===== 操作记录结构 =====
//

// Operation 表示一次完整的操作记录。
// 用于记录系统中的操作行为，包含操作元数据、数据标识、操作者信息以及请求/响应的哈希值。
type Operation struct {
	OpID             string    `json:"opId"             validate:"max=32"`
	Timestamp        time.Time `json:"timestamp"        validate:"required"`
	OpSource         Source    `json:"opSource"         validate:"required,oneof=IRP DOIP"`
	OpCode           OpCode    `json:"opCode"           validate:"required"`
	DoPrefix         string    `json:"doPrefix"         validate:"required,max=512"`
	DoRepository     string    `json:"doRepository"     validate:"required,max=512"`
	Doid             string    `json:"doid"             validate:"required,max=512"`
	ProducerID       string    `json:"producerId"       validate:"required,max=512"`
	OpActor          string    `json:"opActor"          validate:"max=64"`
	RequestBodyHash  *string   `json:"requestBodyHash"  validate:"omitempty,max=128"`
	ResponseBodyHash *string   `json:"responseBodyHash" validate:"omitempty,max=128"`
	// ClientIP 客户端IP地址，仅用于数据库持久化，不参与存证哈希计算
	ClientIP *string `json:"clientIp,omitempty"  validate:"omitempty,max=32"`
	// ServerIP 服务端IP地址，仅用于数据库持久化，不参与存证哈希计算
	ServerIP *string     `json:"serverIp,omitempty"  validate:"omitempty,max=32"`
	Ack      func() bool `json:"-"`
	Nack     func() bool `json:"-"`
	binary   []byte
}

//
// ===== 构造函数 =====
//

// NewFullOperation 创建包含所有字段的完整 Operation。
// 自动完成哈希计算和字段校验，确保创建的 Operation 是完整且有效的。
func NewFullOperation(
	opSource Source,
	opCode OpCode,
	doPrefix, doRepository, doid string,
	producerID string,
	opActor string,
	requestBody, responseBody interface{},
	timestamp time.Time,
) (*Operation, error) {
	log := logger.GetGlobalLogger()
	log.Debug("Creating new full operation",
		"opSource", opSource,
		"opCode", opCode,
		"doPrefix", doPrefix,
		"doRepository", doRepository,
		"doid", doid,
		"producerID", producerID,
		"opActor", opActor,
	)
	op := &Operation{
		Timestamp:    timestamp,
		OpSource:     opSource,
		OpCode:       opCode,
		DoPrefix:     doPrefix,
		DoRepository: doRepository,
		Doid:         doid,
		ProducerID:   producerID,
		OpActor:      opActor,
	}

	log.Debug("Setting request body hash")
	if err := op.RequestBodyFlexible(requestBody); err != nil {
		log.Error("Failed to set request body hash",
			"error", err,
		)
		return nil, err
	}
	log.Debug("Setting response body hash")
	if err := op.ResponseBodyFlexible(responseBody); err != nil {
		log.Error("Failed to set response body hash",
			"error", err,
		)
		return nil, err
	}
	log.Debug("Checking and initializing operation")
	if err := op.CheckAndInit(); err != nil {
		log.Error("Failed to check and init operation",
			"error", err,
		)
		return nil, err
	}

	log.Debug("Full operation created successfully",
		"opID", op.OpID,
	)
	return op, nil
}

//
// ===== 接口实现 =====
//

func (o *Operation) Key() string {
	return o.OpID
}

// OperationHashData 实现 HashData 接口，用于存储 Operation 的哈希计算结果。
type OperationHashData struct {
	key  string
	hash string
}

func (o OperationHashData) Key() string {
	return o.key
}

func (o OperationHashData) Hash() string {
	return o.hash
}

func (o OperationHashData) Type() HashType {
	return Sha256Simd
}

// DoHash 计算 Operation 的整体哈希值，用于数据完整性验证。
// 哈希基于序列化后的二进制数据计算，确保操作记录的不可篡改性。
func (o *Operation) DoHash(_ context.Context) (HashData, error) {
	log := logger.GetGlobalLogger()
	log.Debug("Computing hash for operation",
		"opID", o.OpID,
	)
	hashTool := GetHashTool(Sha256Simd)
	binary, err := o.MarshalBinary()
	if err != nil {
		log.Error("Failed to marshal operation for hash",
			"error", err,
			"opID", o.OpID,
		)
		return nil, fmt.Errorf("failed to marshal operation: %w", err)
	}

	log.Debug("Computing hash bytes",
		"opID", o.OpID,
		"binaryLength", len(binary),
	)
	hash, err := hashTool.HashBytes(binary)
	if err != nil {
		log.Error("Failed to compute hash",
			"error", err,
			"opID", o.OpID,
		)
		return nil, fmt.Errorf("failed to compute hash: %w", err)
	}

	log.Debug("Hash computed successfully",
		"opID", o.OpID,
		"hash", hash,
	)
	return OperationHashData{
		key:  o.OpID,
		hash: hash,
	}, nil
}

//
// ===== CBOR 序列化相关 =====
//

// operationData 用于 CBOR 序列化/反序列化的中间结构。
// 排除函数字段和缓存字段，仅包含可序列化的数据字段。
type operationData struct {
	OpID             *string    `cbor:"opId"`
	Timestamp        *time.Time `cbor:"timestamp"`
	OpSource         *Source    `cbor:"opSource"`
	OpCode           *OpCode    `cbor:"opCode"`
	DoPrefix         *string    `cbor:"doPrefix"`
	DoRepository     *string    `cbor:"doRepository"`
	Doid             *string    `cbor:"doid"`
	ProducerID       *string    `cbor:"producerId"`
	OpActor          *string    `cbor:"opActor"`
	RequestBodyHash  *string    `cbor:"requestBodyHash"`
	ResponseBodyHash *string    `cbor:"responseBodyHash"`
}

// toOperationData 将 Operation 转换为 operationData，用于序列化。
func (o *Operation) toOperationData() *operationData {
	return &operationData{
		OpID:             &o.OpID,
		Timestamp:        &o.Timestamp,
		OpSource:         &o.OpSource,
		OpCode:           &o.OpCode,
		DoPrefix:         &o.DoPrefix,
		DoRepository:     &o.DoRepository,
		Doid:             &o.Doid,
		ProducerID:       &o.ProducerID,
		OpActor:          &o.OpActor,
		RequestBodyHash:  o.RequestBodyHash,
		ResponseBodyHash: o.ResponseBodyHash,
	}
}

// fromOperationData 从 operationData 填充 Operation，用于反序列化。
func (o *Operation) fromOperationData(opData *operationData) {
	if opData == nil {
		return
	}

	if opData.OpID != nil {
		o.OpID = *opData.OpID
	}
	if opData.Timestamp != nil {
		o.Timestamp = *opData.Timestamp
	}
	if opData.OpSource != nil {
		o.OpSource = *opData.OpSource
	}
	if opData.OpCode != nil {
		o.OpCode = *opData.OpCode
	}
	if opData.DoPrefix != nil {
		o.DoPrefix = *opData.DoPrefix
	}
	if opData.DoRepository != nil {
		o.DoRepository = *opData.DoRepository
	}
	if opData.Doid != nil {
		o.Doid = *opData.Doid
	}
	if opData.ProducerID != nil {
		o.ProducerID = *opData.ProducerID
	}
	if opData.OpActor != nil {
		o.OpActor = *opData.OpActor
	}
	if opData.RequestBodyHash != nil {
		hash := *opData.RequestBodyHash
		o.RequestBodyHash = &hash
	}
	if opData.ResponseBodyHash != nil {
		hash := *opData.ResponseBodyHash
		o.ResponseBodyHash = &hash
	}
}

// MarshalBinary 将 Operation 序列化为 CBOR 格式的二进制数据。
// 实现 encoding.BinaryMarshaler 接口。
// 使用 Canonical CBOR 编码确保序列化结果的一致性，使用缓存机制避免重复序列化。
func (o *Operation) MarshalBinary() ([]byte, error) {
	log := logger.GetGlobalLogger()
	log.Debug("Marshaling operation to CBOR binary",
		"opID", o.OpID,
	)
	if o.binary != nil {
		log.Debug("Using cached binary data",
			"opID", o.OpID,
		)
		return o.binary, nil
	}

	opData := o.toOperationData()

	log.Debug("Marshaling operation data to canonical CBOR",
		"opID", o.OpID,
	)
	binary, err := helpers.MarshalCanonical(opData)
	if err != nil {
		log.Error("Failed to marshal operation to CBOR",
			"error", err,
			"opID", o.OpID,
		)
		return nil, fmt.Errorf("failed to marshal operation to CBOR: %w", err)
	}

	o.binary = binary

	log.Debug("Operation marshaled successfully",
		"opID", o.OpID,
		"binaryLength", len(binary),
	)
	return binary, nil
}

// GetProducerID 返回 ProducerID，实现 Trustlog 接口。
func (o *Operation) GetProducerID() string {
	return o.ProducerID
}

// UnmarshalBinary 从 CBOR 格式的二进制数据反序列化为 Operation。
// 实现 encoding.BinaryUnmarshaler 接口。
func (o *Operation) UnmarshalBinary(data []byte) error {
	log := logger.GetGlobalLogger()
	log.Debug("Unmarshaling operation from CBOR binary",
		"dataLength", len(data),
	)
	if len(data) == 0 {
		log.Error("Data is empty")
		return errors.New("data is empty")
	}

	opData := &operationData{}

	log.Debug("Unmarshaling operation data from CBOR")
	if err := helpers.Unmarshal(data, opData); err != nil {
		log.Error("Failed to unmarshal operation from CBOR",
			"error", err,
		)
		return fmt.Errorf("failed to unmarshal operation from CBOR: %w", err)
	}

	o.fromOperationData(opData)

	o.binary = data

	log.Debug("Operation unmarshaled successfully",
		"opID", o.OpID,
	)
	return nil
}

//
// ===== 哈希设置方法 =====
//

// setBodyHashFlexible 根据输入数据类型计算哈希，支持 string 和 []byte。
// 使用固定的 Sha256Simd 算法。
// 如果输入为 nil 或空，则目标指针设置为 nil，表示该字段未设置。
func (o *Operation) setBodyHashFlexible(data interface{}, target **string) error {
	log := logger.GetGlobalLogger()
	log.Debug("Setting body hash flexible",
		"opID", o.OpID,
		"dataType", fmt.Sprintf("%T", data),
	)
	if data == nil {
		log.Debug("Data is nil, setting target to nil")
		*target = nil
		return nil
	}

	hashTool := GetHashTool(Sha256Simd)
	var raw []byte

	switch v := data.(type) {
	case string:
		if v == "" {
			log.Debug("String data is empty, setting target to nil")
			*target = nil
			return nil
		}
		raw = []byte(v)
		log.Debug("Converting string to bytes",
			"stringLength", len(v),
		)
	case []byte:
		if len(v) == 0 {
			log.Debug("Byte data is empty, setting target to nil")
			*target = nil
			return nil
		}
		raw = v
		log.Debug("Using byte data directly",
			"byteLength", len(v),
		)
	default:
		log.Error("Unsupported data type",
			"dataType", fmt.Sprintf("%T", v),
		)
		return fmt.Errorf("unsupported data type %T", v)
	}

	log.Debug("Computing hash for body data",
		"dataLength", len(raw),
	)
	hash, err := hashTool.HashBytes(raw)
	if err != nil {
		log.Error("Failed to compute hash",
			"error", err,
		)
		return err
	}

	*target = &hash
	log.Debug("Body hash set successfully",
		"hash", hash,
	)
	return nil
}

// RequestBodyFlexible 设置请求体哈希值。
// 支持 string 和 []byte 类型，nil 或空值会将 RequestBodyHash 设置为 nil。
func (o *Operation) RequestBodyFlexible(data interface{}) error {
	return o.setBodyHashFlexible(data, &o.RequestBodyHash)
}

// ResponseBodyFlexible 设置响应体哈希值。
// 支持 string 和 []byte 类型，nil 或空值会将 ResponseBodyHash 设置为 nil。
func (o *Operation) ResponseBodyFlexible(data interface{}) error {
	return o.setBodyHashFlexible(data, &o.ResponseBodyHash)
}

//
// ===== 链式调用支持 =====
//

// WithRequestBody 设置请求体哈希并返回自身，支持链式调用。
func (o *Operation) WithRequestBody(data []byte) *Operation {
	_ = o.RequestBodyFlexible(data)
	return o
}

// WithResponseBody 设置响应体哈希并返回自身，支持链式调用。
func (o *Operation) WithResponseBody(data []byte) *Operation {
	_ = o.ResponseBodyFlexible(data)
	return o
}

//
// ===== 初始化与验证 =====
//

// CheckAndInit 校验并初始化 Operation。
// 自动填充缺失字段（OpID、OpActor），执行业务逻辑验证（doid 格式），
// 字段非空验证由 validate 标签处理。
func (o *Operation) CheckAndInit() error {
	log := logger.GetGlobalLogger()
	log.Debug("Checking and initializing operation",
		"opSource", o.OpSource,
		"opCode", o.OpCode,
		"doid", o.Doid,
	)
	if o.OpID == "" {
		o.OpID = helpers.NewUUIDv7()
		log.Debug("Generated new OpID",
			"opID", o.OpID,
		)
	}

	if o.OpActor == "" {
		o.OpActor = "SYSTEM"
		log.Debug("Set default OpActor to SYSTEM")
	}

	expectedPrefix := fmt.Sprintf("%s/%s", o.DoPrefix, o.DoRepository)
	if !strings.HasPrefix(o.Doid, expectedPrefix) {
		log.Error("Doid format validation failed",
			"doid", o.Doid,
			"expectedPrefix", expectedPrefix,
		)
		return fmt.Errorf("doid must start with '%s'", expectedPrefix)
	}

	log.Debug("Validating operation struct")
	if err := helpers.GetValidator().Struct(o); err != nil {
		log.Error("Operation validation failed",
			"error", err,
			"opID", o.OpID,
		)
		return err
	}

	log.Debug("Operation checked and initialized successfully",
		"opID", o.OpID,
	)
	return nil
}