package intelligence_finance_v1_ga

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"
)

// 供应商业务类型常量。
const (
	BizTypeCreateSupplier              = "create_supplier"
	BizTypeQuerySupplierByName         = "query_supplier_by_name"
	BizTypeUpdateSupplier              = "update_supplier"
	BizTypeQuerySupplierByUserDefine   = "query_supplier_by_userDefineCode"
)

// Client 业财连接接口客户端。
type Client struct {
	baseURL      string
	tenantID     string
	clientID     string
	clientSecret string
	signEnabled  bool
	httpClient   *http.Client

	// 各接口路径（可通过 Option 覆盖）
	pathSubmitInvoiceApply            string
	pathQueryInvoiceStatus            string
	pathCreatePayment                 string
	pathQueryPaymentStatus            string
	pathCreateSupplier                string
	pathQuerySupplierByName           string
	pathUpdateSupplier                string
	pathQuerySupplierByUserDefineCode string
}

// Option 客户端配置项。
type Option func(*Client)

// WithHTTPClient 自定义 http.Client。
func WithHTTPClient(c *http.Client) Option {
	return func(cli *Client) { cli.httpClient = c }
}

// WithSignEnabled 是否启用请求签名（钉钉AI表格场景可关闭，签名由AI表格自动完成）。
func WithSignEnabled(enabled bool) Option {
	return func(cli *Client) { cli.signEnabled = enabled }
}

// WithPathSubmitInvoiceApply 设置提交订单开票申请接口路径。
func WithPathSubmitInvoiceApply(path string) Option {
	return func(cli *Client) { cli.pathSubmitInvoiceApply = path }
}

// WithPathQueryInvoiceStatus 设置开票状态查询接口路径。
func WithPathQueryInvoiceStatus(path string) Option {
	return func(cli *Client) { cli.pathQueryInvoiceStatus = path }
}

// WithPathCreatePayment 设置创建付款单据接口路径。
func WithPathCreatePayment(path string) Option {
	return func(cli *Client) { cli.pathCreatePayment = path }
}

// WithPathQueryPaymentStatus 设置支付状态查询接口路径。
func WithPathQueryPaymentStatus(path string) Option {
	return func(cli *Client) { cli.pathQueryPaymentStatus = path }
}

// WithPathCreateSupplier 设置创建供应商接口路径。
func WithPathCreateSupplier(path string) Option {
	return func(cli *Client) { cli.pathCreateSupplier = path }
}

// WithPathQuerySupplierByName 设置根据名称查询供应商接口路径。
func WithPathQuerySupplierByName(path string) Option {
	return func(cli *Client) { cli.pathQuerySupplierByName = path }
}

// WithPathUpdateSupplier 设置更新供应商接口路径。
func WithPathUpdateSupplier(path string) Option {
	return func(cli *Client) { cli.pathUpdateSupplier = path }
}

// WithPathQuerySupplierByUserDefineCode 设置根据用户自定义编码查询供应商接口路径。
func WithPathQuerySupplierByUserDefineCode(path string) Option {
	return func(cli *Client) { cli.pathQuerySupplierByUserDefineCode = path }
}

// NewClient 创建业财连接接口客户端。
//
// baseURL 为平台接口根地址；tenantID 为平台分配的租户唯一标识；
// clientID 为平台分配的应用标识（钉钉AI表格固定为 "dd-ai-table"）；
// clientSecret 为平台分配的密钥，用于请求签名。
func NewClient(baseURL, tenantID, clientID, clientSecret string, opts ...Option) *Client {
	c := &Client{
		baseURL:      strings.TrimRight(baseURL, "/"),
		tenantID:     tenantID,
		clientID:     clientID,
		clientSecret: clientSecret,
		signEnabled:  true,
		httpClient:   &http.Client{Timeout: 30 * time.Second},

		pathSubmitInvoiceApply:            "/invoice/apply",
		pathQueryInvoiceStatus:            "/invoice/status",
		pathCreatePayment:                 "/payment/create",
		pathQueryPaymentStatus:            "/payment/status",
		pathCreateSupplier:                "/supplier/create",
		pathQuerySupplierByName:           "/supplier/queryByName",
		pathUpdateSupplier:                "/supplier/update",
		pathQuerySupplierByUserDefineCode: "/supplier/queryByUserDefineCode",
	}
	for _, opt := range opts {
		opt(c)
	}
	return c
}

// doRequest 发送 POST 请求并解析响应。
func (c *Client) doRequest(ctx context.Context, path string, reqBody, respBody interface{}) error {
	body, err := json.Marshal(reqBody)
	if err != nil {
		return fmt.Errorf("marshal request: %w", err)
	}

	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, c.baseURL+path, bytes.NewReader(body))
	if err != nil {
		return fmt.Errorf("new request: %w", err)
	}

	httpReq.Header.Set("Content-Type", "application/json")
	httpReq.Header.Set("tenant-id", c.tenantID)
	httpReq.Header.Set("client-id", c.clientID)

	if c.signEnabled {
		timestamp := GenerateTimestamp()
		nonce, err := GenerateNonce(32)
		if err != nil {
			return fmt.Errorf("generate nonce: %w", err)
		}
		sign := HmacSHA256Base64(c.clientSecret, timestamp+nonce)
		httpReq.Header.Set("x-bfl-signature-timestamp", timestamp)
		httpReq.Header.Set("x-bfl-signature-nonce", nonce)
		httpReq.Header.Set("x-bfl-signature", sign)
	}

	httpResp, err := c.httpClient.Do(httpReq)
	if err != nil {
		return fmt.Errorf("do request: %w", err)
	}
	defer httpResp.Body.Close()

	respData, err := io.ReadAll(httpResp.Body)
	if err != nil {
		return fmt.Errorf("read response: %w", err)
	}

	if httpResp.StatusCode != http.StatusOK {
		return &APIError{StatusCode: httpResp.StatusCode, Body: string(respData)}
	}

	if err := json.Unmarshal(respData, respBody); err != nil {
		return fmt.Errorf("unmarshal response: %w", err)
	}
	return nil
}

// checkBusinessCode 校验通用响应结构中的业务 code。
func checkBusinessCode(code int, msg string) error {
	if code != 0 && code != 200 {
		return &BusinessError{Code: code, Msg: msg}
	}
	return nil
}

// SubmitInvoiceApply 提交订单开票申请（接口1）。
func (c *Client) SubmitInvoiceApply(ctx context.Context, req *InvoiceApplyRequest) (*InvoiceApplyResponse, error) {
	var envelope struct {
		Code int                  `json:"code"`
		Msg  string               `json:"msg"`
		Data *InvoiceApplyResponse `json:"data"`
	}
	if err := c.doRequest(ctx, c.pathSubmitInvoiceApply, req, &envelope); err != nil {
		return nil, err
	}
	if err := checkBusinessCode(envelope.Code, envelope.Msg); err != nil {
		return nil, err
	}
	return envelope.Data, nil
}

// QueryInvoiceStatus 查询订单开票状态（接口2）。
func (c *Client) QueryInvoiceStatus(ctx context.Context, req *InvoiceStatusQueryRequest) (*InvoiceStatusQueryResponse, error) {
	var envelope struct {
		Code int                        `json:"code"`
		Msg  string                     `json:"msg"`
		Data *InvoiceStatusQueryResponse `json:"data"`
	}
	if err := c.doRequest(ctx, c.pathQueryInvoiceStatus, req, &envelope); err != nil {
		return nil, err
	}
	if err := checkBusinessCode(envelope.Code, envelope.Msg); err != nil {
		return nil, err
	}
	return envelope.Data, nil
}

// CreatePayment 创建付款单据（接口3）。
func (c *Client) CreatePayment(ctx context.Context, req *CreatePaymentRequest) (*CreatePaymentResponse, error) {
	var envelope struct {
		Code int                    `json:"code"`
		Msg  string                 `json:"msg"`
		Data *CreatePaymentResponse `json:"data"`
	}
	if err := c.doRequest(ctx, c.pathCreatePayment, req, &envelope); err != nil {
		return nil, err
	}
	if err := checkBusinessCode(envelope.Code, envelope.Msg); err != nil {
		return nil, err
	}
	return envelope.Data, nil
}

// QueryPaymentStatus 查询支付状态（接口5），响应数据与支付通知一致。
func (c *Client) QueryPaymentStatus(ctx context.Context, req *PaymentStatusQueryRequest) (*PaymentNotifyData, error) {
	var envelope struct {
		Code int               `json:"code"`
		Msg  string            `json:"msg"`
		Data *PaymentNotifyData `json:"data"`
	}
	if err := c.doRequest(ctx, c.pathQueryPaymentStatus, req, &envelope); err != nil {
		return nil, err
	}
	if err := checkBusinessCode(envelope.Code, envelope.Msg); err != nil {
		return nil, err
	}
	return envelope.Data, nil
}

// CreateSupplier 创建供应商（接口6）。
func (c *Client) CreateSupplier(ctx context.Context, req *CreateSupplierRequest) (*CreateSupplierResponse, error) {
	var envelope struct {
		Code int                     `json:"code"`
		Msg  string                  `json:"msg"`
		Data *CreateSupplierResponse `json:"data"`
	}
	if err := c.doRequest(ctx, c.pathCreateSupplier, req, &envelope); err != nil {
		return nil, err
	}
	if err := checkBusinessCode(envelope.Code, envelope.Msg); err != nil {
		return nil, err
	}
	return envelope.Data, nil
}

// QuerySupplierByName 根据名称查询供应商（接口7）。
func (c *Client) QuerySupplierByName(ctx context.Context, req *QuerySupplierByNameRequest) (*QuerySupplierByNameResponse, error) {
	var envelope struct {
		Code int                         `json:"code"`
		Msg  string                      `json:"msg"`
		Data *QuerySupplierByNameResponse `json:"data"`
	}
	if err := c.doRequest(ctx, c.pathQuerySupplierByName, req, &envelope); err != nil {
		return nil, err
	}
	if err := checkBusinessCode(envelope.Code, envelope.Msg); err != nil {
		return nil, err
	}
	return envelope.Data, nil
}

// UpdateSupplier 更新供应商（接口8）。
func (c *Client) UpdateSupplier(ctx context.Context, req *UpdateSupplierRequest) (*UpdateSupplierResponse, error) {
	var envelope struct {
		Code int                     `json:"code"`
		Msg  string                  `json:"msg"`
		Data *UpdateSupplierResponse `json:"data"`
	}
	if err := c.doRequest(ctx, c.pathUpdateSupplier, req, &envelope); err != nil {
		return nil, err
	}
	if err := checkBusinessCode(envelope.Code, envelope.Msg); err != nil {
		return nil, err
	}
	return envelope.Data, nil
}

// QuerySupplierByUserDefineCode 根据用户自定义编码查询供应商（接口9）。
func (c *Client) QuerySupplierByUserDefineCode(ctx context.Context, req *QuerySupplierByUserDefineCodeRequest) (*QuerySupplierByUserDefineCodeResponse, error) {
	var envelope struct {
		Code int                                    `json:"code"`
		Msg  string                                 `json:"msg"`
		Data *QuerySupplierByUserDefineCodeResponse `json:"data"`
	}
	if err := c.doRequest(ctx, c.pathQuerySupplierByUserDefineCode, req, &envelope); err != nil {
		return nil, err
	}
	if err := checkBusinessCode(envelope.Code, envelope.Msg); err != nil {
		return nil, err
	}
	return envelope.Data, nil
}

// ==================== 通知机制辅助 ====================

// ParseNotification 解析通用通知数据。
func ParseNotification(body []byte) (*Notification, error) {
	var n Notification
	if err := json.Unmarshal(body, &n); err != nil {
		return nil, fmt.Errorf("parse notification: %w", err)
	}
	return &n, nil
}

// ParsePaymentNotify 解析支付完成通知数据（接口4）。
func ParsePaymentNotify(body []byte) (*PaymentNotifyData, error) {
	var n PaymentNotifyData
	if err := json.Unmarshal(body, &n); err != nil {
		return nil, fmt.Errorf("parse payment notify: %w", err)
	}
	return &n, nil
}

// VerifyNotificationSignature 校验通知签名。
//
// 平台使用客户提供的验签密钥对原始请求体进行 HmacSHA256 签名并 Base64 编码，
// 通过请求头 x-bfl-signature 传递。verifyKey 为客户在平台配置的验签密钥。
func VerifyNotificationSignature(verifyKey string, rawBody []byte, signature string) (bool, error) {
	if signature == "" {
		return false, &NotificationError{Reason: "empty signature"}
	}
	expected := HmacSHA256Base64(verifyKey, string(rawBody))
	return hmacEqual(expected, signature), nil
}

// hmacEqual 常量时间比较两个 Base64 签名是否一致。
func hmacEqual(a, b string) bool {
	if len(a) != len(b) {
		return false
	}
	var v byte
	for i := 0; i < len(a); i++ {
		v |= a[i] ^ b[i]
	}
	return v == 0
}