// Package fake is an in-process Provider used to exercise the pay v2 pipeline
// end-to-end without any real channel. Real adapters (crypto/alipay/stripe) land
// in P3. provider_ref = "FAKE-"+OutTradeNo+"-"+<nanosecond>; render_type = crypto_address.
// The nanosecond suffix is fake-only: Attempt has uniqueIndex(channel,provider_ref),
// and a retry on the same order/method would otherwise reuse the same OutTradeNo and
// collide. Real channels naturally mint a distinct ref per create call.
package fake

import (
	"context"
	"encoding/json"
	"errors"
	"strconv"
	"sync"
	"time"

	"github.com/wangjia/pay/internal/provider"
)

type Provider struct {
	mu           sync.Mutex
	queryResults map[string]provider.PaidEvent

	supportsRefund bool
	refundRef      string
	refundStatus   provider.PaidStatus
	refundErr      error

	// settleCurrencies overrides the default ["USDT"] capability (测试缝/dev 缝:
	// providerbuild.BuildRegistry 在 MOCK_CHANNEL_ENABLED 下把它设成 ["CNY","USDT"]
	// 以对齐 pangolin 下单实际用的结算币种;默认 nil 时保持既有测试预期不变)。
	settleCurrencies []string

	lastMetadata map[string]string // 测试缝:记录最近一次 Create 收到的 Metadata(jiu 反馈波,验证 gateway 透传)
}

func New() *Provider { return &Provider{queryResults: map[string]provider.PaidEvent{}} }

func (p *Provider) Method() string { return "fake" }

// SetSettleCurrencies overrides Capabilities().SettleCurrencies (测试缝/dev 缝,见字段注释)。
// SettleCurrencies[0] 驱动 gateway.CreateOrder 实际选用的结算币种(设计 §4.1)。
func (p *Provider) SetSettleCurrencies(cs []string) {
	p.mu.Lock()
	defer p.mu.Unlock()
	p.settleCurrencies = cs
}

func (p *Provider) Capabilities() provider.Capabilities {
	p.mu.Lock()
	cs := p.settleCurrencies
	p.mu.Unlock()
	if len(cs) == 0 {
		cs = []string{"USDT"}
	}
	return provider.Capabilities{
		RenderTypes:      []provider.RenderType{provider.RenderCryptoAddress},
		SupportsRefund:   p.supportsRefund,
		SettleCurrencies: cs,
		Regions:          []string{"global"},
	}
}

func (p *Provider) Create(_ context.Context, req provider.CreateRequest) (*provider.Session, error) {
	p.mu.Lock()
	p.lastMetadata = req.Metadata
	p.mu.Unlock()
	exp := time.Now().Add(15 * time.Minute)
	ref := "FAKE-" + req.OutTradeNo + "-" + strconv.FormatInt(time.Now().UnixNano(), 36)

	// render 由 metadata["render"] 驱动(pangolin /buy 联调门控,见 CLAUDE.md 交代);
	// 只影响这里的展示形态,不影响 provider_ref 生成/VerifyCallback/结算。
	switch req.Metadata["render"] {
	case string(provider.RenderRedirect):
		return &provider.Session{
			ProviderRef: ref,
			RenderType:  provider.RenderRedirect,
			Payload: map[string]any{
				"url": "http://localhost:8090/mock-cashier?out_trade_no=" + req.OutTradeNo,
			},
			ExpiresAt: &exp,
		}, nil
	case string(provider.RenderQR):
		return &provider.Session{
			ProviderRef: ref,
			RenderType:  provider.RenderQR,
			Payload: map[string]any{
				"qr_content":     "weixin://wxpay/mock/" + req.OutTradeNo,
				"display_amount": strconv.FormatInt(req.AmountMinor, 10),
				"currency":       req.Currency,
			},
			ExpiresAt: &exp,
		}, nil
	default:
		return &provider.Session{
			ProviderRef: ref,
			RenderType:  provider.RenderCryptoAddress,
			Payload: map[string]any{
				"address":      "TFake" + req.Account.AccountID + req.OutTradeNo,
				"amount_minor": req.AmountMinor,
				"currency":     req.Currency,
			},
			ExpiresAt: &exp,
		}, nil
	}
}

// VerifyCallback 解析测试注入的 JSON 回调体成归一化 PaidEvent。
func (p *Provider) VerifyCallback(_ context.Context, in provider.CallbackInput) (*provider.PaidEvent, error) {
	var b struct {
		ProviderRef string `json:"provider_ref"`
		Status      string `json:"status"`
		AmountMinor int64  `json:"amount_minor"`
		Currency    string `json:"currency"`
	}
	if err := json.Unmarshal(in.Raw, &b); err != nil {
		return nil, err
	}
	if b.ProviderRef == "" {
		return nil, errors.New("fake: missing provider_ref")
	}
	return &provider.PaidEvent{
		ProviderRef:     b.ProviderRef,
		Status:          provider.PaidStatus(b.Status),
		PaidAmountMinor: b.AmountMinor,
		PaidCurrency:    b.Currency,
		Raw:             string(in.Raw),
	}, nil
}

func (p *Provider) Query(_ context.Context, req provider.QueryRequest) (*provider.PaidEvent, error) {
	p.mu.Lock()
	defer p.mu.Unlock()
	if ev, ok := p.queryResults[req.ProviderRef]; ok {
		e := ev
		return &e, nil
	}
	return &provider.PaidEvent{ProviderRef: req.ProviderRef, Status: provider.PaidPending}, nil
}

// LastMetadata returns the Metadata passed to the most recent Create call (test seam).
func (p *Provider) LastMetadata() map[string]string {
	p.mu.Lock()
	defer p.mu.Unlock()
	return p.lastMetadata
}

// SetQueryResult primes Query to report a specific event (test seam).
func (p *Provider) SetQueryResult(providerRef string, ev provider.PaidEvent) {
	p.mu.Lock()
	defer p.mu.Unlock()
	p.queryResults[providerRef] = ev
}

// EnableRefund 令 fake 表现为可退渠道并预置一次退款结果(测试缝)。
func (p *Provider) EnableRefund(refundRef string, status provider.PaidStatus, err error) {
	p.mu.Lock()
	defer p.mu.Unlock()
	p.supportsRefund = true
	p.refundRef = refundRef
	p.refundStatus = status
	p.refundErr = err
}

// Refund implements provider.RefundingProvider (测试缝:忽略入参,回放预置结果)。
func (p *Provider) Refund(_ context.Context, _, _ string, _ int64, _ string) (string, provider.PaidStatus, error) {
	p.mu.Lock()
	defer p.mu.Unlock()
	if p.refundErr != nil {
		return "", provider.PaidFailed, p.refundErr
	}
	return p.refundRef, p.refundStatus, nil
}