package oci

import (
	"context"
	"fmt"
	"io"
	"math"
	"strings"
	"time"

	"github.com/oracle/oci-go-sdk/v65/common"
	"github.com/oracle/oci-go-sdk/v65/ospgateway"
)

// 账单能力封装 OSP Gateway(发票列表/明细/PDF/付款与订阅付款方式)。
// 该服务只在租户主区域提供,所有请求都要携带 ospHomeRegion 并发往主区域。

// Invoice 是一张发票的摘要(InvoiceSummary 的面板投影)。
type Invoice struct {
	ID              string     `json:"id"`
	InternalID      string     `json:"internalId"`
	Number          string     `json:"number"`
	Type            string     `json:"type"`
	Status          string     `json:"status"`
	IsPaid          bool       `json:"isPaid"`
	IsPayable       bool       `json:"isPayable"`
	IsPaymentFailed bool       `json:"isPaymentFailed"`
	Amount          float64    `json:"amount"`
	AmountDue       float64    `json:"amountDue"`
	Currency        string     `json:"currency"`
	TimeInvoice     *time.Time `json:"timeInvoice"`
	TimeDue         *time.Time `json:"timeDue"`
}

// InvoiceLine 是发票内一行费用明细。
type InvoiceLine struct {
	Product   string     `json:"product"`
	OrderNo   string     `json:"orderNo"`
	Quantity  float64    `json:"quantity"`
	UnitPrice float64    `json:"unitPrice"`
	Total     float64    `json:"total"`
	Currency  string     `json:"currency"`
	TimeStart *time.Time `json:"timeStart"`
	TimeEnd   *time.Time `json:"timeEnd"`
}

// PaymentMethod 是订阅上登记的一种付款方式,按 method 分信用卡/PayPal 两形态。
type PaymentMethod struct {
	Method           string     `json:"method"` // CREDIT_CARD / PAYPAL
	CardType         string     `json:"cardType,omitempty"`
	LastDigits       string     `json:"lastDigits,omitempty"`
	NameOnCard       string     `json:"nameOnCard,omitempty"`
	TimeExpiration   *time.Time `json:"timeExpiration,omitempty"`
	Email            string     `json:"email,omitempty"`
	PayerName        string     `json:"payerName,omitempty"`
	BillingAgreement string     `json:"billingAgreement,omitempty"`
}

// ospHomeRegion 解析租户主区域公共名(经测活拿三字码再查区域表);
// 主区域是租户常量,按 tenancy 进程内缓存,免去每次账单调用先付一次远程测活。
func (c *RealClient) ospHomeRegion(ctx context.Context, cred Credentials) (string, error) {
	if v, ok := c.homeRegions.Load(cred.TenancyOCID); ok {
		return v.(string), nil
	}
	info, err := c.ValidateKey(ctx, cred)
	if err != nil {
		return "", fmt.Errorf("resolve osp home region: %w", err)
	}
	r, ok := RegionByKey(info.HomeRegionKey)
	if !ok {
		return "", fmt.Errorf("resolve osp home region: unknown region key %q", info.HomeRegionKey)
	}
	if cred.TenancyOCID != "" {
		c.homeRegions.Store(cred.TenancyOCID, r.Name)
	}
	return r.Name, nil
}

// ospInvoiceClient 构造发票服务客户端并指向主区域;region 同时用于请求参数。
func (c *RealClient) ospInvoiceClient(ctx context.Context, cred Credentials) (ospgateway.InvoiceServiceClient, string, error) {
	region, err := c.ospHomeRegion(ctx, cred)
	if err != nil {
		return ospgateway.InvoiceServiceClient{}, "", err
	}
	ic, err := ospgateway.NewInvoiceServiceClientWithConfigurationProvider(provider(cred))
	if err != nil {
		return ospgateway.InvoiceServiceClient{}, "", fmt.Errorf("new invoice client: %w", err)
	}
	applyProxy(&ic.BaseClient, cred)
	ic.SetRegion(region)
	return ic, region, nil
}

// ListInvoices 实现 Client:分页列出租户发票;year>0 时只取该自然年
// (按 timeInvoice 窗口过滤),为 0 拉全量。
func (c *RealClient) ListInvoices(ctx context.Context, cred Credentials, year int) ([]Invoice, error) {
	ic, region, err := c.ospInvoiceClient(ctx, cred)
	if err != nil {
		return nil, err
	}
	req := ospgateway.ListInvoicesRequest{
		OspHomeRegion: &region,
		CompartmentId: &cred.TenancyOCID,
		Limit:         common.Int(ospPageLimit),
	}
	if year > 0 {
		req.TimeInvoiceStart = &common.SDKTime{Time: time.Date(year, 1, 1, 0, 0, 0, 0, time.UTC)}
		req.TimeInvoiceEnd = &common.SDKTime{Time: time.Date(year+1, 1, 1, 0, 0, 0, 0, time.UTC)}
	}
	var out []Invoice
	for {
		resp, err := ic.ListInvoices(ctx, req)
		if err != nil {
			return nil, fmt.Errorf("list invoices: %w", err)
		}
		for _, item := range resp.Items {
			out = append(out, toInvoice(item))
		}
		if resp.OpcNextPage == nil {
			return orEmpty(out), nil
		}
		req.Page = resp.OpcNextPage
	}
}

// ospPageLimit 是 OSP 网关列表接口的每页条数;不传时服务端默认页极小,
// 几百行发票明细要串行翻几十页(实测单请求被拖到 40s+)。
const ospPageLimit = 100

// ListInvoiceLines 实现 Client:分页列出一张发票的全部费用行。
func (c *RealClient) ListInvoiceLines(ctx context.Context, cred Credentials, internalInvoiceID string) ([]InvoiceLine, error) {
	ic, region, err := c.ospInvoiceClient(ctx, cred)
	if err != nil {
		return nil, err
	}
	var out []InvoiceLine
	var page *string
	for {
		resp, err := ic.ListInvoiceLines(ctx, ospgateway.ListInvoiceLinesRequest{
			OspHomeRegion:     &region,
			CompartmentId:     &cred.TenancyOCID,
			InternalInvoiceId: &internalInvoiceID,
			Page:              page,
			Limit:             common.Int(ospPageLimit),
		})
		if err != nil {
			return nil, fmt.Errorf("list invoice lines: %w", err)
		}
		for _, item := range resp.Items {
			out = append(out, toInvoiceLine(item))
		}
		if resp.OpcNextPage == nil {
			return orEmpty(out), nil
		}
		page = resp.OpcNextPage
	}
}

// DownloadInvoicePdf 实现 Client:整读发票 PDF,超出 maxBytes 视为异常。
func (c *RealClient) DownloadInvoicePdf(ctx context.Context, cred Credentials, internalInvoiceID string, maxBytes int64) ([]byte, error) {
	ic, region, err := c.ospInvoiceClient(ctx, cred)
	if err != nil {
		return nil, err
	}
	resp, err := ic.DownloadPdfContent(ctx, ospgateway.DownloadPdfContentRequest{
		OspHomeRegion:     &region,
		CompartmentId:     &cred.TenancyOCID,
		InternalInvoiceId: &internalInvoiceID,
	})
	if err != nil {
		return nil, fmt.Errorf("download invoice pdf: %w", err)
	}
	defer resp.Content.Close()
	data, err := io.ReadAll(io.LimitReader(resp.Content, maxBytes+1))
	if err != nil {
		return nil, fmt.Errorf("download invoice pdf: %w", err)
	}
	if int64(len(data)) > maxBytes {
		return nil, fmt.Errorf("download invoice pdf: exceeds %d bytes", maxBytes)
	}
	return data, nil
}

// PayInvoice 实现 Client:按订阅当前默认付款方式支付发票,email 接收回执。
func (c *RealClient) PayInvoice(ctx context.Context, cred Credentials, internalInvoiceID, email string) error {
	ic, region, err := c.ospInvoiceClient(ctx, cred)
	if err != nil {
		return err
	}
	_, err = ic.PayInvoice(ctx, ospgateway.PayInvoiceRequest{
		OspHomeRegion:     &region,
		CompartmentId:     &cred.TenancyOCID,
		InternalInvoiceId: &internalInvoiceID,
		PayInvoiceDetails: ospgateway.PayInvoiceDetails{Email: &email},
	})
	if err != nil {
		return fmt.Errorf("pay invoice: %w", err)
	}
	return nil
}

// ListPaymentMethods 实现 Client:汇总各订阅上登记的全部付款方式。
func (c *RealClient) ListPaymentMethods(ctx context.Context, cred Credentials) ([]PaymentMethod, error) {
	region, err := c.ospHomeRegion(ctx, cred)
	if err != nil {
		return nil, err
	}
	sc, err := ospgateway.NewSubscriptionServiceClientWithConfigurationProvider(provider(cred))
	if err != nil {
		return nil, fmt.Errorf("new osp subscription client: %w", err)
	}
	applyProxy(&sc.BaseClient, cred)
	sc.SetRegion(region)
	var out []PaymentMethod
	var page *string
	for {
		resp, err := sc.ListSubscriptions(ctx, ospgateway.ListSubscriptionsRequest{
			OspHomeRegion: &region,
			CompartmentId: &cred.TenancyOCID,
			Page:          page,
		})
		if err != nil {
			return nil, fmt.Errorf("list payment methods: %w", err)
		}
		for _, sub := range resp.Items {
			out = appendPaymentMethods(out, sub.PaymentOptions)
		}
		if resp.OpcNextPage == nil {
			return orEmpty(out), nil
		}
		page = resp.OpcNextPage
	}
}

func toInvoice(v ospgateway.InvoiceSummary) Invoice {
	inv := Invoice{
		ID:          deref(v.InvoiceId),
		InternalID:  deref(v.InternalInvoiceId),
		Number:      deref(v.InvoiceNumber),
		Type:        string(v.InvoiceType),
		Status:      string(v.InvoiceStatus),
		Amount:      money(v.InvoiceAmount),
		AmountDue:   money(v.InvoiceAmountDue),
		TimeInvoice: sdkTime(v.TimeInvoice),
		TimeDue:     sdkTime(v.TimeInvoiceDue),
	}
	if v.IsPaid != nil {
		inv.IsPaid = *v.IsPaid
	}
	if v.IsPayable != nil {
		inv.IsPayable = *v.IsPayable
	}
	if v.IsPaymentFailed != nil {
		inv.IsPaymentFailed = *v.IsPaymentFailed
	}
	if v.Currency != nil {
		inv.Currency = deref(v.Currency.CurrencyCode)
	}
	return inv
}

func toInvoiceLine(v ospgateway.InvoiceLineSummary) InvoiceLine {
	line := InvoiceLine{
		Product:   deref(v.Product),
		OrderNo:   deref(v.OrderNo),
		Quantity:  money(v.Quantity),
		UnitPrice: money(v.NetUnitPrice),
		Total:     money(v.TotalPrice),
		TimeStart: sdkTime(v.TimeStart),
		TimeEnd:   sdkTime(v.TimeEnd),
	}
	if v.Currency != nil {
		line.Currency = deref(v.Currency.CurrencyCode)
	}
	return line
}

func appendPaymentMethods(out []PaymentMethod, opts []ospgateway.PaymentOption) []PaymentMethod {
	for _, opt := range opts {
		switch v := opt.(type) {
		case ospgateway.CreditCardPaymentOption:
			out = append(out, creditCardMethod(v))
		case *ospgateway.CreditCardPaymentOption:
			out = append(out, creditCardMethod(*v))
		case ospgateway.PaypalPaymentOption:
			out = append(out, paypalMethod(v))
		case *ospgateway.PaypalPaymentOption:
			out = append(out, paypalMethod(*v))
		}
	}
	return out
}

func creditCardMethod(v ospgateway.CreditCardPaymentOption) PaymentMethod {
	return PaymentMethod{
		Method:         "CREDIT_CARD",
		CardType:       string(v.CreditCardType),
		LastDigits:     deref(v.LastDigits),
		NameOnCard:     deref(v.NameOnCard),
		TimeExpiration: sdkTime(v.TimeExpiration),
	}
}

func paypalMethod(v ospgateway.PaypalPaymentOption) PaymentMethod {
	return PaymentMethod{
		Method:           "PAYPAL",
		Email:            deref(v.EmailAddress),
		PayerName:        strings.TrimSpace(deref(v.FirstName) + " " + deref(v.LastName)),
		BillingAgreement: deref(v.ExtBillingAgreementId),
	}
}

// money 把 SDK 的 float32 金额转为 float64 输出;四舍五入到 4 位小数,
// 抹掉精度转换产生的二进制噪音(如 603.53 变 603.5300293)。
func money(p *float32) float64 {
	if p == nil {
		return 0
	}
	return math.Round(float64(*p)*10000) / 10000
}